Film-Tech Forum ARCHIVE: cp50 prob/questions

This is topic cp50 prob/questions in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=003083

Posted by Dave Ganoe (Member # 53) on 02-12-2002, 03:22 PM:

I just recently bought a cp50 that was supposed to be in working order when removed from service. It contains cat113c and 280t cards. I hooked it up and can only get sound in bypass mode? Does this mean that something in the system is defective or could it possibly be hooked up wrong? I hooked the stereo cell up as explained in the manual and left and right outputs to my amp as in the manual. Also, is SR the same as SRD? Thanks for any info.

Posted by Scott Norwood (Member # 30) on 02-12-2002, 03:37 PM:

Do you have a fader connected to it? The CP50 requires an external fader; do a search through the forum and you'll find a post that tells you what you can get at Radio Shack that will do the trick. The Dolby remote auditorium fader will also work.

Another possibility is that one of the cards is either bad or not seated properly. The output card could have the levels set too low, also.

SR is not the same as SRD. SR is a newer noise reduction scheme; it's like Dolby A, but better. Since you have the cat 280T cards, you can play SR prints properly. IF you want to play older Dolby A prints, you will need a set of cat. 22 cards. SRD is Dolby's digital sound system; all (well, most) SRD prints also have an SR optical track.

Posted by Gordon McLeod (Member # 33) on 02-12-2002, 03:41 PM:

1st the ce;ll doesn't connect to amps but to preamp input
I am assuming that you had sound when you had the pink noise generator in it so that would determin that the eq and fader cards are working
And since there is sound in bypass the preamp card is working os the problems are possibly the bass extension card or the cat 110L put in incorrectly the NR cards or the meter cards

Posted by Steve Kraus (Member # 476) on 02-12-2002, 05:04 PM:

I will go with Scott's guess that there is no fader hooked up; an external one (just a simple potentiometer) is mandatory. Gordon, I doubt he has a pink noise generator card so pretty much *anything* except the pre-amp and power supply could be bad or in wrong.

Some trouble shooting hints: In by-pass you are sending sound directly from the pre-amp to the output by way of the 113C control card. Normal signal progression is from left to right, preamp, NR cards, meter card (the meters themselves are driven by the NR cards but the meter card is also where the Academy roll-off filter for mono is found). Then assuming you have a Cat. 150 2:4 decoder the slot before it will either contain a subwoofer card (Cat. 160) OR the 110L link card Gordon refers to which must be in place to pass the signal unless someone has jumpered the connections on the backplane. Then the 150, then the EQ, and finally the output card. Note that after the 4 channel electronic fader the output card contains only 2 line drive amps and these are for Center and Surround. The L and R signals are routed BACk to the NR cards to make use of line amps found on them (it let them save a few bucks), then all four appear at the output terminals. If you have a prehistoric stereo decoder, there will be an LCR card where we talked about the link card OR subwooder card, and then a Surround card (two bolted together actually) in the slot where we talked about the Cat. 150 2:4 card. I doubt you have that old stuff since the 113C card indicates a CP-50 that has been updated. Hope this helps you trace it out.

Posted by Mark Gulbrandsen (Member # 72) on 02-12-2002, 06:24 PM:

Yes, You need a 100K linear potentiometer for a fader on the CP-50. You won't get a peep without it. If you have it all hooked up correctly and you achieve Dolby tone without any other problems then the preamp section is ok.

On a CP-50 though the power supply is barely big enough to power the unit with the 113C card and a pair of CAT 280T's. If U plug in a new 108C preamp card it will lower the B+ to the point that some of the cards cease to function properly. If it seems that the level cannot be achieved or if it comes up sounding ok and then fades out, check the B+ lines and you'll probably find one of them quite a bit lower than it should be. On a unit this old its also a good idea to replace the power supply caps inside the power supply. I've found many of them actually leaking electrolyte. Several have had hum problems stemming from aged power supply components. Ya have to stop and consider that most electrolytics have a rated life of 5 to 10 years and many of the 50's out there are far older than that!

On another note replacing the caps will not correct a sagging power supply problem either. There are two options for this problem. The forst and expensive way out is to buy the newer uprated power supply fomr Dolby at about 450.00. The second way which is cheaper and actually better is to build a whole new supply for it and can the original which is way to under rated for an upgraded 50. I ahve a completely upgraded 50 in my screening room and the supply I built is competely regulated on all lines and cost under 75.00 to build with all new parts, including a new toroid power transformer. The supply is now outboarded as well. The CP-50 can be a great sounding unit, easily surpassing the sound quality of the newer digital processors quite easily. For best performance you should also have the new cat 417 fader card in there as well to handle the higher playback levels of SR tracks.
Mark @ GTS

Posted by Dave Ganoe (Member # 53) on 02-12-2002, 09:15 PM:

You guys are so smart. I wish I knew more, Im learning. I checked to be sure all the cards are seated properly and they are. Where would I connect the fader control to? THere is a fader control on the cat113c that adjust volume in bypass mode, does it not work the same if it were not in bypass or do I need another fader control somewhere else? Would it be better to go back to a cat112? MARK, the power supply you talked about building, do you have plans for building it? Thanks.

Posted by Steve Kraus (Member # 476) on 02-12-2002, 09:29 PM:

The fader on the 113C is just for bypass. Connect the main fader to the terminal strip on the back, upper left, 2nd from left (SK2), "AUTO FADER." It connects accross terminals 5 and 6. Your potentiometer will have a center contact for the wiper and two end contacts. One wire goes to the wiper; the other goes to the that end of the pot. which represents full volume (clockwise when viewed from the front).

No reason to go back to the 112 although the funky mechanical buttons were kind of fun (if unfamiliar, these are buttons whose internal labels changed as you push or release them). The purpose of the 113C was to enable format control via automation via the usual contact closures. The 112 not only had mechanical buttons also required several to be pushed (NR on or off, Stereo or mono, Surround on or off).

Posted by Mark Gulbrandsen (Member # 72) on 02-12-2002, 09:37 PM:

Tom, Yes I have the plans around here someplace. I'll dig em out and e-mail them to you.The supply would only be needed if you upgrade beyond a cat 113c and two cat 280T's. The stock unit will run that much but JUST BARELY!
There is a connection terminal block at the top near the center that is labeled for the fader. Connect the wiper of the 100K linear taper potentiometer to SK2, terminal 5, labeled auto/fader. Connect the top of the pot to SK2 terminal 6 which is a B+ terminal. The other end of the pot is not connected. If the fader works backwards after connection, just move the wire at the top of the pot to the oposite end. Now that was easy, wasn't it?
Mark @ GTS

Posted by Steve Guttag (Member # 268) on 02-12-2002, 10:40 PM:

The quick and dirty varification of the fader card...short the "Auto Fader" terminals (BTW nobody uses the designator B+ when referring to the Dolby power supply rails except Mark G. so don't go looking for it, the CP-50 runs on +24, +12 and -12VDC)

As Mark has pointed out...the power supply (Cat. 114) was a very simple brute force supply that had just enough current to handle a stock CP-50. I've seen the +/- 12 volt rails dip down below 10 volts! (they start out at around +/-15 volts).

Ideally, you would want a good +/- 15 volt supply and +24 volt supply...the +/-15 volt rails are the ones that take the biggest hit when you upgrade. I believe the NR cards use only the +24 volt rail since they must be backwards compatible to old pro-audio systems.

Steve

------------------
"Old projectionists never die, they just changeover!"

Posted by Frank Angel (Member # 248) on 02-13-2002, 12:49 AM:

For those of you who know these CPs backwards and forwards, is there any easy way to install a switch to knock out the Academy curve out of the circuit -- a manual switch would do fine or would this require drastic surgery on the card? I would sure like to be able to switch that high-end roll-off out of the Mono format as we get lots of foreign mono prints that don't need that roll-off. And plenty of later Hollywood prints too for that matter. Leave the high-cut filter out and it sounds much better.

How do I know? because we had down and dirty setup in one booth where we were just going directly from the cells directly into a standard Shure mic preamp with no EQ at all and the thing sounded great -- plenty of high-end. I remember the first film we ran on that setup was YELLOW SUBMARINE and it sounded almost like the kind of response you got with mag. I remember being very impressed. We added an outboard EQ and only had to give the bottom end a bit of a boost but other than that, the high-end was very smooth.

I don't see the need to use any curve at all since the Academy curve was only a low-pass filter to cut down on the high-end noise of the old tracks. It wasn't any compensation for high-end boost in the recording process. We played all those mono prints from the 60s and 70s and they sounded fine before we had enough money to get real gear (Dolby). Rolling off the high-end just seems like it would be a step backwards. Any thoughts?

Posted by Ray Derrick (Member # 1001) on 02-13-2002, 01:52 AM:

Frank, I think the easiest way to dispense with the Academy filter may be to run in Dolby Stereo mode/no surround and turn off the noise reduction. There may be diode mod for this but I don't know the CP50 all that well. How about it Steve or Steve? Otherwise you could add a switch which shorts the two NR Signal lines to ground, which appear at pins 8 (and 9) on each NR card slot.

One big difference though between your Shure preamp and the CP50 is the slit compensation circuit which adds about 16dB of boost at some frequency in the region of 10 to 20kHz, depending on your slit size. This would most likely make your unfiltered mono films sound very brittle and crackly. Add to this the effects of any high end boost in the room eq and your unfiltered mono films may sound really awful.

A more preferrable alternative may be to modify the Academy filters for a more gentle roll-off, say 6dB/octave rather than 12dB/octave. This could probably be done simply by shorting out inductors L101 and L201 on the Cat109 card. This should give a 6dB/octave rolloff with a 3dB down point at about 5.4kHz. If you want to try this let me know and I can look into it further for you.

------------------
Ray Derrick
President/Chief Engineer
Panalogic Corporation Sydney, Australia
Phone: 61 (0)2 9894 6655 Fax: 61 (0)2 9894 6935

Posted by Mark Gulbrandsen (Member # 72) on 02-13-2002, 05:17 AM:

Well, Steve and Steve are probably sound asleep right now but I'm up heading to south central Utah on a call so I thought I'd grab this one. Steve, sorry for the generalization use of B+, but it is just that, a generalization to say there is juice at that point, It is used quite often in some areas of the industry, probably more often that we'd like to see it at any rate. Its a terminal with available electrons and thats all one really needs to know when hooking it up, especially if one is not knowledgable about this stuff.

Frank,
I don't think turning the NR on and running that way is a good idea as the NR may add its own artifacts to an un-encoded audio program. This is further complicated in units that have a CAT 113C automation switch card. On this card there is no NR off and on button, its patterned after a CP-55/65 processor that only allows certain pre-selected formats that are designed into the 113C card. Fortunately there is a mono(01) select button on this card.

Adding a switch for disabling the academy filter is easy and there are two ways to do it. The quick and and easy way is to lift the junction of R102(R-202) and L-101(L202) and insert a spst dip switch there to open , or close this junction. There is plenty wide open space to add one of these into the card quite easily. You could also add a DIP switch to the rear of the backplane as well just by opening up the pin 10 trace of the meter card and inserting the same DIP switch there. This is labeled + for NR off on the drawing(there's that darn refernce to b+ again right on the CP-50 schematic Steve, courtesy of none other than Dolby!)Either way is good but I prefer the switch installed on the meter card as its out of sight and out of mind from other operators curiosity. The final option is to pull L101 (201) off the pcb entirely to disable the darn thing all together. I always felt it had bit to steep of roll off and perhaps Dolby intended it to be that way. Only poor mono tracks with lots of over modulation, or very worn tracks will be more noticable. Clean mono tracks sound lots better IMHO without the filter in place. Even old variable density tracks can sound great with the filter removed, although there will be a bit more noticable background noise on these.
Mark @ GTS

Posted by Steve Guttag (Member # 268) on 02-13-2002, 08:24 AM:

>>"This is labeled + for NR off
on the drawing(there's that darn refernce to b+ again right on the CP-50 schematic Steve, courtesy of
none other than Dolby!)"<<

Boy do you like to use things out of context! The "+" in this instance is for a logic input such that it is active high or high for on. The "+" merely refers to "high". There is no mention of "B" in there.

Now back to the subject...personally, I think you are dead wrong on the Academy filter. It is proper to be in there for mono film, even recent ones. While I don't doubt that there may be SOME films that did not have a pre-emphasis, that wouldn't be the norm. Mono films were mixed with the presumption that you had the typical sounding theatre from the '30s or so (before equalization in the current sense was used). With a modern cinema processor, one can tune a theatre for "flat". This equalization does not make your theatre look like one from the '30s. The Academy filter does and thus makes your theatre sound closer to what the director/mixers heard when they mixed the film.

As to not running with the filter making the films sound "better" or brighter..., perhaps, subjectively but it isn't they way they were supposed to sound. Your position is similar to that which I heard back in the '70s when using cassette recorders...encode with Dolby-B and playback without...after all, using Dolby-B on the playback kills the highs! No it really doesn't (unless your recorder was rather poor) but most people tend to boost the treble to make it crisp....if that is the case, then use the treble control, not the filter or NR.

Now, if you insist on having a switchable filter, I'd vote for putting the switch on the rear and switch pin-10 (open for filter off, closed to follow normal CP-50 logic)

Steve

------------------
"Old projectionists never die, they just changeover!"

Posted by Mark Gulbrandsen (Member # 72) on 02-13-2002, 02:15 PM:

Steve, I am just trying to keep things in layman terms for those that could care less if its logic level, b+, b-,c+ or ground.
Mark

Posted by Steve Kraus (Member # 476) on 02-13-2002, 07:47 PM:

When I worked at a feature post production center we had a CP50 in our largest screening room and I had it modified so I could feed dubbers and other gear through it. It bears mentioning here that on a stock 50 the non-sync/mag inputs are switched directly to the outputs--no EQ, no fader, no nuttin. I modified it so I could feed into the pre-amp card just before the changeover switching FET's. This way I had two Lt/Rt inputs to feed dubbers to. A couple of small switches on a plate attached to the preamp card did the optical vs. "other" switching. I had a selector switch on a rackplate to allow other sources such as 16mm (being mono, it fed both Lt and Rt lines). To avoid the Academy rolloff when NR was off I had the switch others have described--I put mine right on the meter card between the meter. There were probably more elegant ways to do this but it worked well. David Gray from Dolby told me where to tap in from memory on his cel phone.

Posted by Gordon McLeod (Member # 33) on 02-13-2002, 09:25 PM:

There was a small daughter board from Dolby that allowed Mag/Nonsync to flow through the eq and fader

Posted by Mark Gulbrandsen (Member # 72) on 02-13-2002, 09:34 PM:

Gord, The post facility didn't have a dime to spare for the daughter board. The rent was something like 40K a month there. Steve, is this figure correct. The place made it cause Steve was very good at winging it with just about any request.
Mark @ GTS

Posted by Gordon McLeod (Member # 33) on 02-13-2002, 10:09 PM:

The last 10 cp50's that we got for hauling away and scrapping all had the daughter board on them

Posted by Dave Ganoe (Member # 53) on 02-13-2002, 11:14 PM:

Thanks to all the info in getting the CP50 to work. Add the fader did the trick. Hope no one minds more questions. How do I know which switch puts the unit in sr mode? Is it the button that says stereo? Are the led's on the 280T cards supposed to light up when it is in sr mode? Thanks.

Posted by Brad Miller (Member # 2) on 02-13-2002, 11:17 PM:

Since you are basically just swapping out the cat22 Dolby "A" cards with cat280T Dolby "SR" cards, yes pressing "stereo" or "NR" or whatever it is labeled will enable Dolby SR.

Posted by Ray Derrick (Member # 1001) on 02-14-2002, 05:11 AM:

Mark said: "(B+ is) a terminal with available electrons.."

Gee whiz Mark, I could jump on this nit picking bandwagon and say "no it's not, B- is a terminal with available electrons, B+ is a terminal with a depletion of electrons". But no, I wouldn't be another nit picker and say that!

------------------
Ray Derrick
President/Chief Engineer
Panalogic Corporation Sydney, Australia
Phone: 61 (0)2 9894 6655 Fax: 61 (0)2 9894 6935

Posted by Mark Gulbrandsen (Member # 72) on 02-14-2002, 08:14 AM:

Ray, What kind of picker are you? I set that up for Steve G and now U gave it away.......

Dave,
Set Dolby level with the CAT 22's in place then put in the CAT 280T's and run. This is the way Dolby reccommended it should be done years ago when these things came out.
Mark @ GTS

Posted by Ben Wales (Member # 92) on 02-14-2002, 08:23 AM:

The last 10 cp50's that we got for hauling away and scrapping all had the daughter board on them

Gordon- I assume you mean the Dolby Cat223 board that was connected to the backplane on the CP50?.

Posted by Mark Gulbrandsen (Member # 72) on 02-14-2002, 08:48 AM:

The reason he hauled off 10 perfectly good CP-50 stereo processors was to have enough cards to get all the EPRAD Starscopes he installed all over Ontario running properly!
Mark @ GTS

Posted by Gordon McLeod (Member # 33) on 02-14-2002, 08:13 PM:

Actually the cards were used to upgrade some CP200's to aux rack for LE and RE and PQ 1/3 octave
Also some were converted to EX units

Posted by Ray Derrick (Member # 1001) on 02-15-2002, 05:45 AM:

Sorry Mark, I guess "nit picking" is probably one of those purely Australian expressions. I think it derives from the habit of monkeys etc to pick the nits (small insects) from each other's fur. We regard a person who finds fault over the smallest, most insignificant things as a "nit picker". B+ is fine with me, I know what you are talking about.

Also I don't FULLY subscribe to the "it must be played the way the director intended" line... I am getting really sick of hearing that from people who have never been involved on the creative side of sound (or vision) production. The truth is half the directors in Hollywood wouldn't know good sound if it stood up and slapped them in the face! Just ask some of the audio fraternity. So often it is the sound team who create great soundtracks and the director just gives the nod and takes the credit for it (or just says "make it louder"!!). If you can make a mediocre mono soundtrack sound better, then why the hell not? Most sound professionals that I know would be grateful for the assistance.

Also with reference to Steve G's comparison about the practice of playing Dolby B encoded cassette tapes back with the NR switched off because it "sounds better".. the problem here was that high speed duplication (which is used for all general release pre-recorded cassettes) completely screws the Dolby B process because it results in lower high frequency levels than the master. So people HAD to turn the NR off to get decent highs. Also because of the considerable variation in record and reproduce levels from one cassette player to another, the only time Dolby B is guaranteed to work correctly is when a cassette is recorded and played back on the same properly aligned deck.

------------------
Ray Derrick
President/Chief Engineer
Panalogic Corporation Sydney, Australia
Phone: 61 (0)2 9894 6655 Fax: 61 (0)2 9894 6935

Posted by Brad Miller (Member # 2) on 02-15-2002, 12:15 PM:

By "the same properly aligned deck", I assume you also refer to having the bias fine tuned for each cassette. Even if the bias is adjusted for one particular brand of tape, each batch of them will be slightly different, enough to cause Dolby mistracking.

Posted by Frank Angel (Member # 248) on 02-15-2002, 01:20 PM:

DAMN you guys are good! I think I am going to give it a shot -- adding the switch on the rear to disable the Academy filter. Dolby modified our unit -- upgraded caps and put in the cat 113 automation which as Mark points out, has limited the flexibility by only offering preset versions of the formats -- no ablity to choose NR on or off, for example.

Steve G, you are right about consumers and Dolby B -- I started out as a audio recording engineer and no matter how much I explained that using the NR to boost high end was counter productive, no one paid any attention. The same with Dolby SVA tracks in the early days when they originally double inventoried Dolby and non-Dolby prints, Dolby quietly backed away from the double inventory concept (bad marketing fly in the Dolby ointment) and seemed to imply that Dolby prints with A type noise reduction were "compatible." Seemed to me, if you have type A noise reduction, there is no way you can play that back without decoding it, unless you like the sound of swooshing high end what sounds like someone constantly turning a treble control up and down. In the recording studio any engineer worth his salt would laugh if anyone suggested a tape recorded with Dolby A was compatable with decks not equipped with an A decoder. How Dolby got away with suggesting that it was possible to play Dolby A prints without decoding was a mystery to me.

So I wholeheartedly agree with the negative effects of switching out NR when it should be there, but I disagree with the parallel made to the Academy curve. The steep Academy attenuation was not designed as a compensation for a mirror boost in the optical recorder, but simply as a poor attempt to compensate for the noisy optical tracks of the 30's and 40's. As soundtracks got a lot cleaner and the recording technology improved, the need to roll off the high end as a way to attenuate hiss became unnecessary. I just don't see the need for it with the very well recorded films of the 60's and 70's. I am going to follow all the good advice here and knock the thing right out of the processor -- switchable, of course.

Posted by Mark Gulbrandsen (Member # 72) on 02-15-2002, 04:03 PM:

Frank,
I definately agree with U about the fact that the Academy Curve was brought about for reduction of noise form early soundtracks. The older variable density stuff was sometimes pathetic in the noise department. I've also heard really great variable density too. Several old I.B. prints I ahve are variable density and sound fantastic with a red led reverse scanner on them. But if they are noisy its really, really noisy! It wasn't till the advent of variable area that noise levels got better and finally with the addition of noise reduction shutters got to where it is today.
Mark @ GTS

Posted by Steve Kraus (Member # 476) on 02-15-2002, 06:37 PM:

Mark: The rent wasn't quite that bad but it was substantial and elscalated every year plus the share of expenses went up as well. Three screening rooms was too much which is why #3 later became a large editing suite. Glad I was not a principal of that business.

Frank Angel opined:
>How Dolby got away with suggesting that it was possible to play
>Dolby A prints without decoding was a mystery to me.

The Dolby A system works akin to a set of compandors working independently in 4 frequency bands. Encoding with no decoding ought to just have the effect of bringing up the low level sounds. That shouldn't be too deleterious to the sound. With the presumption that the non-Dolby theatres might have poorer listening conditions (background noise, bleed through, etc.) it hypothetically could even help.

Of course that's just the theory and we all know how well some theories work out.

Posted by Steve Guttag (Member # 268) on 02-16-2002, 12:03 AM:

<putting on my best Andy Rooney voice>

Have you ever noticed that the people that don't mind altering how a film is played back tend to be the people that don't make/sell/use Dolby brand equipment?

Ok, as to the Dolby-B thing on cassette decks Ray D., I specifically said recorders since it was my experience that the Harry-Homeowner types would indeed record their favoite LPs (or even off the radio) tuns with Dolby NR on but play them back with the NR off (using the same cassette recorder).

Brad as to Dolby cassette decks (particularly of the 70s/early 80s) proper calibration ment EQ, Bias and Level. In fact, I believe it was a requirement that all Dolby equipped decks have a Dolby reference level indicated on the "VU" meters. The double-D symbol would show up on the meters often or sometimes just a unique "tick" mark and this represented Dolby-Level. Since the Dolby NR system doesn't operate on the signal above Dolby-level, it is essential that that point be established to ensure the proper operating area of the companders. A fact that remains with us today, even with SR and with films.

Gordon, the Cat. 223 did indeed allow the various non-syncs to use the VCAs but alas it did not allow them to use the EQs...they were only used by optical.

As to the analogy of the Academy curve vs. Dolby-B on cassette decks, there is truth in that. Hollywood films mixed for monural, did have a pre-emphasis to boost the HF on the record-end since the Academy response was the presumed response of the "typical" un-equalized auditorium. Playing the track back without the academy curve on an equalized theatre would have the sound play back brighter..

And "B+" hasn't been in theatre layman's terms since tubes went out of vogue!

Sheesh,

Steve

------------------
"Old projectionists never die, they just changeover!"

Posted by Ray Derrick (Member # 1001) on 02-16-2002, 04:20 AM:

Steve, that didn't sound at all like Andy Rooney. When it comes to impersonation, my best advice is - don't give up your day job!

BTW the only people who make Dolby equipment are (is) Dolby, unless you hadn't noticed.

I don't see what Dolby has to do with playing back Academy (or otherwise) mono films. Besides, I seem to recall reading somewhere that it is not uncommon (outside of the USA, of course) for films to be recorded in mono using SVA tracks, in other words, full-range non-Dolby mono. To play back such a film with Dolby's Academy filter in circuit is in my book tantamount to audio sacrilege.

Now lets get down to the nitty gritty. An Academy mono film will not play back correctly, by YOUR standards, on one of your Dolby processors. Why? Because there is NO slit compensation in pre-Dolby equipment and NO 1/3 octave room equalisation, the very equipment that was designed to play Academy mono films. So play the film back on a Dolby processor and you have total non-compliance with what the director intended. Yes?, No? So where is your consistency, where are your standards Mr Guttag? The optical Academy filter (used in ALL current sound processors) is supposedly the same curve as has applied since the early days of optical film sound, so to be accurate, shouldn't Dolby turn off the slit compensation AND shouldn't they turn off or modify the room eq when playing an Academy mono film? Is all this toying with the spectral response what "the director intended"?

Besides, were you there in the mixing theatre when they were mixing Gone With The Wind or Ben Hur? Do you really know what the director or the sound mixer really heard? Things have changed an awful lot since Dolby came on the scene and standardised mixing theatres (or at least attempted to). As far as I have been able to ascertain, prior to 1975 the use of optical record/playback simulators was rare if unheard of, so the soundtrack usually sounded a lot better in the mixing theatre than after it went to film. (Anyone with definitive information on this point is most welcome to contact me).

Also I must say that I must be a Harry-Homeowner type (whatever that is) because in my younger days I too was guilty of turning off the Dolby B because it sounded like crap, nothing like the original material that I had just recorded. It wasn't until I was old enough to afford audiophile-class cassette decks that I realised the problem was due to the crappy alignment of the cheap decks, not with the NR system.

------------------
Ray Derrick
President/Chief Engineer
Panalogic Corporation Sydney, Australia
Phone: 61 (0)2 9894 6655 Fax: 61 (0)2 9894 6935

Posted by Mark Gulbrandsen (Member # 72) on 02-16-2002, 08:07 AM:

Steve said.....
"And "B+" hasn't been in theatre layman's terms since tubes went out of vogue!"

In My Rush Limbaugh voice......
Steve has apparently been living in his own little solid state only world a bit too long. Tubes are back and in vogue better than ever, even more than they ever were in the audio industry when there were ONLY tubes. Where have you been my friend? Stuck between two reel to reel machines a bit too long perhaps? Steve you need to get out in what is now called the new tube world and check it out! Leave Film-Tech behind for an hour and splore the new tube world on the net.

The Rushter voice continuing.....
He also had the audacity to say in an important forum that......

"Have you ever noticed that the people that don't mind altering how a film is played back tend to be the people that don't make/sell/use Dolby brand equipment? "

Holy cow, that is a load of ! The Liberals should get ahold of this guy and hire him...

What brand you sell has nothing to do with wanting to modify how something sounds or not, or how something operates. Thats one of the most ludicrous statements ever made on this network! In fact if you get to the facts you push a brand of processor that cannot be modified at all, except through the operating software itself. Get the manufactirer to modify it for you.....yea, right! My friend, your stuck in the muck selling that piece of equipment! If you want to limit yourself to that one processor, thats your choice, but there are many of us out there, including the man above this posting that can see right through the limitations of that processor. Although your brand is all I used to sell, but since that company has shot themselves in the head byb producing ONLY one processor, I wouldn't sell your brand of processor anymore if my life depended on it as I don't ever want to limit what my customers can or can't do in their theatres.

Get with it... The man above this posting has by far the best ounding processor out there, and it actually been out there for quite some time. Steve, you should do your customers a favor and climb aboard on his wagon before it leaves the station for the next town.
Mark @ GTS

P.S. There is one advantage at least from a buisness standpoint to the processor that you do sell and that is in 7 years or so major semiconductor components will become obsolete and you'll be selling your customers another processor! That'll mean a good P&L that year for you.

Posted by Steve Guttag (Member # 268) on 02-17-2002, 03:15 AM:

Actually, Andy really isn't in my list of impersonations but who would know in ASCII?

>>"BTW the only people who make Dolby equipment are (is) Dolby, unless you hadn't noticed."<< Yeah, and?

Ray there is total consistancy with my arguement. The Dolby academy filter is designed to undo the affects of the slit loss correction and the b-chain equalization such that it will make the theatre the ideal academy curve.

In fact, when in magnetic mode, the Cat. 109 has less of a roll off since the slit loss compensation is not an issue (and the mag head is presumed already flat to 12KHz) hence why the Cat. 109 has three modes (flat, optical, and magnetic)...there is also a link that can be used to roll off the bass. The idea is to superimpose the ideal Academy filter over a tuned room.

>>"Besides, were you there in the mixing theatre when they were mixing Gone With The Wind or Ben Hur?<<"

Actually....

No I wasn't and neither were any of us here. But I have measured many theatres that were around when they were new films and unfortunately, that was was before the R2 and such analyzers could "Record" their response. An unequalized period speaker playing through a screen in the typical barn of a theatre (say from 800-1500 seats) was not as good as most would like to think. In fact, the Academy curve is a pretty good represenation....once one moves into the 50s, things seem to get better but nothing like when the "X" curve comes into play in the '70s and beyond.

The "harry-homeowner" reference is bascially anyone that isn't concerned with the technicalities of a particular item (be it electronics, mechanics, plumbing, carpentry...etc) they just use it...a common term here or at least in my part of the country (mid-Atlantic)

As to Dolby-B and cassette decks, no doubt there were bad ones or merely uncalibrated ones...for the most part, I only had what I would call "mid-fi" equipment like Sharp or Pioneer and never had a problem with Dolby-B or that new fangled tape stuff CrO2 (only once or twice used FeCr02). Later in life, I got a Nakamichi but found I could get my Pioneer CT-F1250 to sound every bit as good but not even the Nak could sound as good as my cheapest Reel-to-Reel (Teac A-3300-SX)

Whilst you may have turned off your NR switch due to mistracking, I know a bunch of guys that did cuz it sounded brigher and brighter must be better.

And now over to Mark G.....

Mark you ignorant slut......

Perhaps you wish tubes were used like they used to be in theatres (we are talking about theatre right?) but rightly or wrongly they aren't...even in the home market they are only a nitche.

If you wanted to make your arguement, you should have stated that when the CP-50 came out, many of the theatres they went in WERE running on tubes and hence the B+ reference.....

>>"Holy cow, that is a load of <offensive symbol deleted>! The Liberals should get ahold of this guy and hire him...What brand you sell has nothing to do with wanting to modify how something sounds or not, or how something operates.

Hmmm I said something to the effect (regarding the non-Dolby manufacturers, dealers and users tending to not mind altering how a film is played back) one of the manufacturers have chimed in, a dealer (you have chimed in) and a user (none yet but it may happen).

While a difference of philosophy, generally the Dolby method has been one plays it back the way it was recorded, other methods often offer alterations either by design or by happenstance and even feature it.

BTW, I'm generally regarded as a conservative or a moderate.

>>"Thats one of the most ludicrous statements ever made on this network!"<<

Actually, a lot of you comments tend to fall into that category as you tend to fly off half-cocked...as in this case.

>>"your stuck in the muck selling that piece of equipment! "<<

Not hardly. The CP-650 has it's place just like other equipment and unlike your comments may otherwise indicated, the CP-650 is only but one of the processors I place (not push and you say). But if you want Dolby Digital, it is a pretty good bang for the buck, particulalry if you plan to play conventional hollywood fare and possibly pro-AC3 or DVDs.

>>"If you want to limit yourself to that one processor, thats your choice, but there are many of us out there, including the man above this posting that can see right through the limitations of that processor."<<

I don't but your comments like:

>>"I wouldn't sell your brand of processor anymore if my life depended on it"<<

Show that you would exclude it even if it would make sense. How is that serving your customers?

>>"Get with it... The man above this posting has by far the best ounding processor out there, and it actually been out there for quite some time. Steve, you should do your customers a favor and climb aboard on his wagon before it leaves the station for the next town. Mark @ GTS"<<

Now this one needs some addressing....

But first, did you legally change your last name to "@ GTS" And furthermore, why must their be a sales pitch in most of your posts?

As to Ray and the Panastereo equipment...surprise I have sold it. In fact, not just any unit, but with the CSP-4600 (70mm) and the best remote control to ever grace a cinema processor...it's got not one, not two, but three volume knobs on it (music, film and booth monitor). The CSP-1200 had already knocked out the CP-65 for me before Dolby canned it. It is what the CP-65 shoulda been. So don't lecture me on the train leaving the station, please get yourself on the train and leave. So far the only issues with it for me have been relatively minor and almost none affect the end user. Even Brad would forget about his beloved CP-65s for the CSP-1200

As to your silly comment on obsolete semi-conductors, that is an issue for all manufacturers, I believe the Pana (and I'm sure others) use Analog Devices components and other single source parts, blink your eye and they can be gone, it isn't just digital stuff. Analog Devices seems to can parts outta nowhere faster though, I know they did it to me once.

Mark, I have no issues with Ray, we do have differing philosophies on pre-Dolby sound (that we have discussed long before this thread reared it's ugly head (in private so don't bother with the search).

Ray, I don't worship Dolby, in fact, the last processor I really liked that they brought out was the CP-200 and it still ranks #1 in my book for what it is and when it came out. Heck, by stuffing a diode, you can even nix that bad old Academy filter from mono (or in my case Perspecta Stereo) films!

Now one thing I wish the CSP-1200s in the states would get is the metal backs on the EQ cards and gold plated jumpers like the Aussies have!

Lastly, Mark, if you want to continue this, please do it via e-mail or by phone.

Steve

------------------
"Old projectionists never die, they just changeover!"

Posted by Mark Gulbrandsen (Member # 72) on 02-17-2002, 10:54 AM:

Hey Steve, There's nothing wrong with continuing this here......I'm not mad about anyhing. Continue it off site. Whats to hide?

To get one thing clear. In the future, I'll post my name depending on where I am typing from such as Mark @ GTS, or Mark @ Home, or Mark @ Idaho, or Mark @ Colorado, etc. OK. Also, Whats wrong with a little plug for the company U work for. MANY other dealers do it here. Are you saying that they are also doing a sales pitch as well. Well, at least in general my pitch is usually smaller than their pitch. Perhaps you don't want to do a sales pitch for your company and I respect that, but don't criticise others for doing so. Many of us here are proud of where we work, who we work for and our accomplishments in the field.

I have no interests in selling ANY of our GTS customers a CP650, or anybodys digital based MAIN SYSTEM PROCESSOR for that matter. There is no need for a digital based processor at all. Based on my experience which is not just with digital based cinema equipment, but also with broadcast and lighting equipment as well, its a fact that being digital based only spells trouble in River City sooner or later. Remember there are still thousands of CP-50's out there humming along just fine.

Also, Compare the sound of the 650 to the CSP-1200 sometime in a diorect A to B setup......Yes, you'll be back on Ray's train. GTS's customers will only be getting the best sounding unit!
Also.... Over the past 6 months or so a number of GTS's and other local dealers customers have had so much trouble with SRD tracks on brand new prints(let alone used)that we at GTS have actually considered switching entirely to selling only DTS digital playback on jobs in the future. Well, as it turns out they will be getting the best bang for the buck as that combo is still less $$, and WILL prove more reliable, and repairable overall. If someone HAS to have an SRD playback system then they'll get a DA-20 and a CSP. Simple as that, and nothing wrong with it either. In fact I have a specially configured CSP 70mm system quoted in an 8 perf 70mm system that will be going in later this year. There is nothing else to put in that sort of system unless its custom built. Dolby can't guarantee all parts availability for CP-200's anymore. As a result, I will no longer consider the 200 viable anymore in an application like this. So much for the 200 even though it WAS my favorite too. However, I have made up my mind to leave it behind, theres a better sounding unit out there that'll keep going for along time.

I'm curious about you claiming tubes to be a niche market these days.....I think the hundreds(literally) of audio manufacturers around the world that produce ONLY tube gear would be suprised to hear that, including Western Electric. Steve, Ya don't reopen a mothballed major Vacuum tube manufacturing plant for a small niche market my friend!

Yes, Obsolete semiconductors are a real problem for everyone, I agree. What it really boils down to on this issue is servicability of a given piece of equipment.....
But that will be less of a problem for GTS, and our customers. We will have no problem finding small qualtities of semis to take care of what ever analog processors I've sold. Ultras units being the exception there with their custom chips. but I don't sell them either. When Ultras semi is extinct they WILL have to be replaced with a new processor as well. Good P&L that year for alot of dealers!

The bigger problem here is that when the digital Semi's are no longer available, a given manufacturer will stop supporting repair of the boards in the units. REMEMBER, HE IS THE ONLY ONE THAT CAN FIX THEM, YOU CAN'T! Once he stops repairing them you're undeniably stuck in the muck with that given unit no matter what brand. Even if you can find small quantities of these digital semis its doubtful that you could fix the board. You might also need a closely gaurdrd software program to burn into a new semi too. Good luck getting that,and then U need an EROM burner too. It also requires EXPENSIVE surface mount soldering stations to repair them. All the while, my customes will keep on going like the everready bunny with their CSP-1200 even if all the semis in their DA-20, or DTS are extinct.

Lastly, I never place a piece of equipment anywhere. I PUSH what in my experience is the right equipment to sell to what ever job. I have never had a job come along that is right for only a completely digital based processor and don't forsee a job like that. Pushing good equipment to a customer based on alot of experience is what a good salesman/technicians does. Weather it be a more expensive route, or less expensive route to go, it WILL be the right way to go and the longest lived/best sounding route as well.
Mark @ GTS
P.S. Just for the record I am neither liberal or conservative. I would consider myself completely neutral from all that gobblediegoop!

Posted by Gordon McLeod (Member # 33) on 02-17-2002, 11:20 AM:

Actually Mark all the those "proprietary chips" are just house coded numbers stamped on prodution stock
If you do a bit of reasearch on what happens on each pin it is amazing the cross references you come up with

Posted by Mark Gulbrandsen (Member # 72) on 02-17-2002, 01:02 PM:

Yes Gord,
That is true alot of the time(and true about the semi's in the JS series units) but I wouldn't sell a brand of equipment based on the fact that they "MAY" be the same part as some other semi. Another thing to consider is that sometimes these semis are specially selected so they will work properly in a circuit and to save the manufacturer the headach of having to select them himself. It is VERY common for semis to be custom made for broadcast aplications. And then there is the old addage of you also need the software to go on the blown chip! This problem has happened in the lighting equipment industry alot. Thats why there is a Canadian company that makes nothing but retrofit rack computers for older dimmer racks. If you think stereo processors are expensive, take look at the price of a new dimmer rack and the labor to tear out the old and put in the new. Needless to say this Canadian company has done very well with their ideas and we have also done very well selling their computers.
But I think U missed the main point above. That is that there are certain boards that have to go back to the factory for repair. When the factory stops supporting repair of them you're sh!t out of luck no matter what product it may be.
While I'm certainly more than happy to attempt to revive a certain unit of a customers even if it may mean building some other equivelent circuit around an unavailable part. That is fine where it can be cost effectively done while maintaining the performance and reliability of that piece of equipment. But it sometimes is better to just replace the whole unit.
Mark @ New GTS Shop

Posted by Steve Kraus (Member # 476) on 02-17-2002, 02:15 PM:

Hehehe...the only true B+ comes from a B battery!

(For the uninitiated who wonder why we have C, D, AA, AAA, etc. but no A or B those two were the batteries in the original tube-type portable radios and it was the B battery that supplied the high positive potential to the tubes' plates, hence B+. Tube-based car radios also needed B+ and you'd be amazed at how they turned the 6VDC car battery power of the era into B+ given that steady DC won't go through a transformer. I'd explain but one shouldn't discuss vibrators while kids may still be up!)

Posted by Gordon McLeod (Member # 33) on 02-17-2002, 03:16 PM:

Actually that is why they have null offset pots around them and it isn't hard to repare and recal yourself

Posted by Steve Guttag (Member # 268) on 02-17-2002, 06:12 PM:

Actually, it isn't the signature line or even the Mark @ GTS that is so offensive (though it is true that was the example I used so I can see your response) but looking at the rest of your response look how many times you say blah, blah, blah, blah GTS customers blah blah blah and we at GTS blah blah blah blah or ever your blatent classless discussion of pricing in other posts. Who give a cares what GTS customers are doing?

>>"Also, Compare the sound of the 650 to the CSP-1200 sometime in a diorect A to B setup"<<

In a theatre running Dolby Digital? Sure, the CSP-1200 DA-20 method will certainly cost more but playing through a sheet just how may extra tickts do you think yor GTS customers will sell for the extra cost?

>>"Over the past 6 months or so a number of GTS's and other local dealers customers have had so much trouble with SRD tracks on brand new prints "<<

Sounds more like an indicment of GTS technicans than the format. While the stray defective reel does show up on all of the digial formats, I haven't seen this surge of bad Dolby digital prints in the last 6 months. If you don't know how to set up your digital readers (above the projectors and in the soundheads) perhaps GTS should get someone that can.

Regarding the CP-200, on this we agree...I too have left it behind now that there is a viable alternative unless there is some odd reason for the CP-200.

>>"All the while, my customes will keep on going like the everready bunny with their CSP-1200 even if all the semis in their DA-20, or DTS are extinct"<<

You forgot SDDS in there...surprising since the 1000 is already just about unservicable. But before the CP650 or CP-500 become unservicable, film as the main stream medium will probably be so the issue will be moot. However, the CP650 will handle the likely DCinema sound formats, in the digital domain, all the way through to the outputs!

What you push, I place...I place the correct piece of equipment, you push what you want.

Steve

------------------
"Old projectionists never die, they just changeover!"

Posted by Mark Gulbrandsen (Member # 72) on 02-17-2002, 07:09 PM:

Steve its getting obvious that your scraping at the bottom of the barrel here. Saying that I/we at GTS don't know how to align an SRD reader is very slanderous in and of itself. Please be a bit more dignified in what you post here on this forum, everyone will appreciate it. I tend to be a bit more humble than most, and try never to be slanderous in any way and I thought you were that sort of person too.

Steve, You know that I'm every bit as qualified as U are to do a simple alignment, and we both use pretty much the same equipment and so on. You yourself have stood up for me at least once in this forum when I was being attacked by some one, I can't remember even what it was about. Needless to say I appreciated that very much, but now you are attacking me, and for no reason, just like he did. Your attempted indictment is a joke. If you want to ignore the fact that the prints are the problem thats fine but, but its not something I'd ignore or even could if I wanted to. I've driven lots of miles only to diagnose for a customer a bad section of a certain reel of the SRD track(many of the problems I found woulda killed the SDDS as well but not the DTS). I've come across many different problems ranging from light fogging, damage to the track in a certain area, mis-printed track than ran off center and then back on, etc. I'd be happy to let U speak to any of our customers about these occurances we go through every now and then. About half are first run and the other half sub run. Due to this occuring once in a while, there are many theatre owners that flat out shy away from SRD completely after talking to other area theatre owners. And yes, They all know each other too so the word spreads and that compounds the problem regarding any particuluar format. It seems they attack DTS the least, but they've all paid for new UG kits too!

BTW: All of these readers but two are cat 700/701's except the two which are late model basement style. Can I help it if enone of these readers can read a defective print? Also there's no finger to point here except to the labs in these cases. Dolby's system is a good one and one that I've always supported as you well know.

For some reason or other It seems like alot of poor quality prints are getting shipped up to these more remote places, just to dump them someplace and get some run out of them. Perhaps they still have the additude that patrons in Wheatfield, Colorado won't know the difference. Don't forget, there is some QC still going on in the labs and some prints are still graded. We had a batch of Harry Potter prints that all had snagged sprocket holes all the way through the print! Many theatres here had to fight with the print on the platter just so it would run, looked like a cloverleaf.
Getting a new print didn't cure that problem as the new prints were exactly the same.

Don't get me wrong, I don't DISLIKE SRD at all, just the consiquences it sometimes brings to our customers, and then to us, yes, at GTS.

You also said "What you push, I place"
That doesn't make sense as you are saying that we both sell the same stuff. True to some extent I guess!

And lastly, Careless price discussion? Where? When? I'm more than happy to let anyone know what price we will sell something for on this site or anyplace else. Thats what buisness and being competitive are all about my friend. Sorry if you didn't like the price I gave out.....
Mark @ Home
P.S. Panastereo also makes D-Cinema Processor as well.
SDDS, Whats that? Nothing really viable that I've heard about......

Posted by Gordon McLeod (Member # 33) on 02-17-2002, 08:53 PM:

Okay lets bury the hatchet guys or get out the boxing gloves at showest

Posted by Brad Miller (Member # 2) on 02-17-2002, 09:22 PM:

Time to kiss and make up guys. Either that or Joe will Photoshop you two "making up" and you will forever regret it!

I will interject one thing though, I have seen lab quality really decline in these last couple of years (most noticeably from Deluxe Hollywood, but that's not anything new). However I've not seen any degredation in SRD tracks. I guess the exchanges don't like you guys in Utah!

Brad @ Film-Tech

Posted by Richard Fowler (Member # 893) on 02-17-2002, 09:23 PM:

Jeeez....nice discussion....reminds me of the nickname I give myself as a dealer......pinata doll....where the client, vendor, competition beat me with a mental stick to see how many goodies they can get....Mark@Home...is not that the name of the audio rack manufacturer that supplies Smart ( PanaStereo's relative ) with cabinets??? Another sly, shameful plug

Richard Fowler
TVP-Theatre & Video Products Inc. ( Plug - I own the company ) www.tvpmiami.com

Posted by Richard Fowler (Member # 893) on 02-17-2002, 09:35 PM:

Ironic....I am flying out Monday night to address Dolby SRD playback in the field and to assist ad agencies to supply proper sound elements for advertising prints in SRD for Cinemas....three locations in five days....Dolby is constantly prodding the labs to maintain standards, but we live in an imperfect world. Photoshop....reverse Marks pose and it would be a very "cheeky" kiss.
Richard Fowler
TVP-Theatre & Video Products Inc. www.tvpmiami.com

Posted by Gordon McLeod (Member # 33) on 02-17-2002, 09:40 PM:

Brad get Joe to get out the photoshop anyway

Posted by Mark Gulbrandsen (Member # 72) on 02-17-2002, 09:41 PM:

Guys, Fortunately its not a constant problem but it has been enough of a pain to warrant serious consideration before I push,,,er I mean place any more SRD systems out there. The same goes for digital based processors. In the last two years I've had enough CP-500's dump on me to last a lifetime. They are all now left on 24/7 with back up supplies so they don't dump. I've also trained at least one customer on how to re-load the setup with the Load500 software so I don't have to do the 820 mile round trip just for that.

All of the films in a three state area come out of SLC. I do not have much of a problem in Colorado though, at least so far.

Hey, Photoshop is not such a bad idea at all, I just got the 6.0.1 upgrade too. Could the SRD tracks be photoshoped back to normal? Heck, they could at least be sharpened and gamma corrected all automatically too. Darn, this version can even be automated!
Mark Still @ Homebutnotforlong
P.S.
In case none of you have figured out why I use the @ GTS or @ what ever feature, its is cause my last name is so darn long that no one can pronounce it or let alone spell it correctly anyway! I am also hiding from those funny guys that ride aound here on bicycles that do recruting. Sorry I'll keep my last mane to myself as long as they're on the loose!

Posted by Wes Hughes (Member # 981) on 02-17-2002, 09:51 PM:

MUST plug the CP-650's. I have 5 in service for two years...from what I understand I was one of the first handful of theatres to install them. Hands down my first choice (coupled with penthouse reader only) for a cinema sound processor.

Posted by Mark Gulbrandsen (Member # 72) on 02-17-2002, 09:53 PM:

Wes, What other processors did you try out before selecting the 650?
Mark @ Home

Posted by Steve Guttag (Member # 268) on 02-17-2002, 09:57 PM:

Mark,

Slanderous? Certainly not. But I don't necessarily agree with you that the prints were necessarily at fault. In just what way were they at fault? Was the density off? Did the blocks move into the perforation area or move laterally out of range? Was the azimuth out of range...just what was so wrong with them?

As to how good you are on tweeking the SRD (or SDDS) systems as compared to myself, I can not say. I can say that I have not had the problems you are describing. I do tend to do more than just a "basic" alignment though. I even get SDDS tracks to run reliably...only the 2000 series spaz have I not been able to control...the 3000 series systems have been solid. (and not to let DTS feel left out, no problems getting them running at their best either).

As to the GTS pricing, put it in the Buy/Sell section not as part of a film-handlers forum information. I'll have to do a search but I recall a reference or two to dealer pricing and that is supposed to be confidential.

I'm done.

Steve

------------------
"Old projectionists never die, they just changeover!"

Posted by Mark Gulbrandsen (Member # 72) on 02-17-2002, 10:08 PM:

Steve,
Have had damaged film(new in can), Laterally misprinted, fogged film, and completely lightstruck soundtrack area only(this one was odd). Can't remember seeing a film with bad azimuth. I had a hunk of the laterally misprinted one for quite a while. It was pretty pathetic to see it. Something happened in the darkroom on that one!
Mark @ Home

Posted by Joe Redifer (Member # 3) on 02-18-2002, 02:10 AM:

I don't need Photoshop. What's going on is apparently quite obvious. Check out Mark G lookin' at Steve's toosh in Guttag's member photo while Steve gives the camera his bedroom eyes. Coincidence? And look at Mark G's photo. Think Mark G is pointing at Christie spray paint? Nope. He's pointing at the hotel room in the distance where Steve is anxiously awaiting him.

Posted by Ray Derrick (Member # 1001) on 02-18-2002, 08:58 AM:

I am almost afraid to open my mouth again, at least in this thread, but here goes anyway..

Firstly, sorry if any of my comments were responsible for triggering the "spirited exchange" between Mark and Steve. Mark, thank you very much for your generous comments, they are very much appreciated. Steve, you know I value and respect your opinions and I regret that we do not always see eye to eye, but it would be a boring world if we all agreed on everything.

Secondly, I just wanted to clear the air regarding my view on the relevence of playback standards to the original post in this thread. Since Dolby became involved with film soundtracks and to their eternal credit, there have been well defined standards which many of us in the industry have supported and tried to maintain or improve upon. The difficulty lies in soundtracks from the pre-Dolby era, when standards were few and far between and records as to what standards and methods were applied are not so readily available.

The approach taken by Dolby for handling "legacy" soundtracks was a reasonable one, but one which compressed more than half a century of evolving technology into one solution, Dolby's Academy filter. The filter is applied in two forms, one for optical and one for magnetic the latter being a sort of half strength version of the former. The problem with this approach is that it assumes the worst case for ALL soundtracks, so films mixed in the early 1970's get the same treatment as films mixed in the 1940's.

The case for a fixed optical Academy filter is more justifiable than the magnetic filter, because there was a pre-emphasis applied to optical mono films which theoretically needed de-emphasis on playback, a situation that does not however apply to magnetic. I believe there is a good case to make the magnetic filter variable and/or maybe even apply single-ended noise reduction techniques to reduce noise and hiss on very old or abused prints. We have been designing just such a system for our Panastereo CSP4600 magnetic processor.

Franky I had not considered applying this to optical mono, at least until I read Dave's post, and his observations raised the possibility that maybe the optical filter deserved a closer look.

That's it! I am not advocating changing the way films are played in a general sense, as Steve seems to have assumed, I am simply for trying to get the very best results possible from pre-Dolby films and not just writing them off as "they sound lousy and that's the way they are supposed to sound".

------------------
Ray Derrick
President/Chief Engineer
Panalogic Corporation Sydney, Australia
Phone: 61 (0)2 9894 6655 Fax: 61 (0)2 9894 6935

Posted by Mark Gulbrandsen (Member # 72) on 02-18-2002, 09:43 AM:

Ray,
It definately had nothing to do with anything you said. All of us here really appreciate all the help and suggestions you post.
Steve and I are the best of friends and have been for along time. As a result we can do this sort of exchange with out ending up blowing up one or the others home. Hope to see you at Showest!

I've pretty much made up my mind to seitch over to your products in all future installations. I was once one of those that had jumped on the digital bandwagon however I've gotten back off and for very good reasons. I'm back to the school that would prefer to keep any digital attachment in a seperate box.
Mark @ GTS

Posted by Steve Guttag (Member # 268) on 02-18-2002, 11:14 AM:

>>"Steve, you know I value and respect your opinions and I regret that we do not always see eye to eye, but it would be a boring world if we all agreed on everything."<<

You got that right!

The variable filter is probably the best approach (bass and treble, if you ask me)

As to pre-Dolby films as they go throughout the decades from sound on film I would say that the sound systems of the era certainly did change with the late '40s early '50s seeing a turning point but having measured many of these old theatres with the older sound systems, the frequency responses were not too flattering and clearly dialoge was the most emphasised portion of the frequency spectrum. I think the Academy filter on the Cat. 109 pretty well represents such systems. It is logical to presume that the films were mixed for such systems, at least to some degree.

Presuming your new filter design allows for this (and lesser filtering) then I think the best of all worlds will be had.

Steve

------------------
"Old projectionists never die, they just changeover!"

Posted by Gordon McLeod (Member # 33) on 02-18-2002, 11:16 AM:

Actually Dolby allowed for that anyway with the cleanup mode that the cat22 can be put into

Posted by Ray Derrick (Member # 1001) on 02-19-2002, 06:53 AM:

Steve, we have no intention of modifying the optical Academy filter in our processors, it is only the mag filter that I was referring to.

Gord, I gather you are referring to that little red box with the sliders (a Cat whatever, I've forgotten the number) that you can plug a Cat 22 card into and use it for single ended noise reduction. I used to use one in post production in my days as a mixing engineer, very handy device. However that is a studio tool not a cinema product.

------------------
Ray Derrick
President/Chief Engineer
Panalogic Corporation Sydney, Australia
Phone: 61 (0)2 9894 6655 Fax: 61 (0)2 9894 6935

Posted by Gordon McLeod (Member # 33) on 02-19-2002, 09:33 AM:

The origanl 360 cinema unit that held a cat 22 had a button called cleanup that did exactly what the variable cat43? redbox did but in a fixed mode for dirty and scratched optical tracks

Posted by Ray Derrick (Member # 1001) on 02-19-2002, 06:36 PM:

Well Gord, I guess you learn something every day.

------------------
Ray Derrick
President/Chief Engineer
Panalogic Corporation Sydney, Australia
Phone: 61 (0)2 9894 6655 Fax: 61 (0)2 9894 6935

Posted by Gordon McLeod (Member # 33) on 02-19-2002, 06:54 PM:

A wise man once told me "the day that you cease to learn you die"
So I desperatley try to learn something everyday and as insurance leave part of the chapter unread till tomorrow

Posted by Steve Kraus (Member # 476) on 02-19-2002, 07:25 PM:

Gordon, I think you're referring to the Model 364 which had the cleanup mode although I believe the box carried the circuitry not the NR card. The 364 (containing a Cat. 22) was used with an E2 holding a Cat. 64 EQ card to do Dolby Mono. Isn't that where the head EQ part of the older Cat. 64's were used (as slit loss correction before the signal goes back to the Cat. 22)?

Posted by Gordon McLeod (Member # 33) on 02-19-2002, 07:43 PM:

You are correct it is the 364