Film-Tech Forum ARCHIVE: Devry xd help

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Posted by Jas Verlen (Member # 8420) on 09-19-2014, 11:54 AM:

Quentin's announcement re 70mm inspired me to start running 35mm again.

My Devry Xd runs well. However sound is not so hot. Unit was redone by Marty Bahn 20 years ago for Dolby. I run it into a cheap radio shack mic preamp and then to two integrated Pyramid amps (line inputs) to two speakers. Sound is better than has been before but key problem is if you turn it up to hear low voices the dynamic range is so great the action sequences are way too loud.

Do you think a dolby cp50 or similar would solve this? If so ebay looks like a lot of junky stuff 'as is'. Anyone have a unit like this that is complete and running for a fair price?

Thanks!

Posted by Mitchell Dvoskin (Member # 751) on 09-19-2014, 12:06 PM:

Yes, a Dolby processor should fix that problem. I would not waste money on a CP-50, they only do mono and either Dolby A or Dolby SR, but not both without an add-on card and processor.

Go for a CP-55, CP45, or CP-65 (best).

Posted by Jas Verlen (Member # 8420) on 09-19-2014, 12:38 PM:

Thank you Mitchel. I see one on ebay that sounds complete but then says "no power supply". I wasnt aware these units need a separate power supply...?

Posted by Sam D. Chavez (Member # 1841) on 09-19-2014, 05:33 PM:

I would not bother with a 45. Not many repair parts and pretty mediocre performance and no headroom. Go for the 65. There are a lot of spares for this and the 55.

Posted by Mark Gulbrandsen (Member # 72) on 09-19-2014, 05:41 PM:

Sam... Don't tell Louis that!

I did a red led reverse scanner some years ago for a friend's XD and it worked just fine. But it's all a custom job.

Mark

Posted by Marcel Birgelen (Member # 6801) on 09-19-2014, 06:06 PM:

And why not a Dolby CP-650? It supports all essential analog formats, including Dolby A and SR and you can even use SRD if you get a reader and if you want to run digital sound. As a bonus: There are still plenty of spare components to be found as this machine is still quite commonly used, even in DCI setups.

Posted by Jas Verlen (Member # 8420) on 09-19-2014, 07:20 PM:

Ok thanks everyone for their input - sounds like stay away from the 45 and 50.

Ebay is scaring ime on this - lots of 'as is' and 'no return' - probably trashed. Anyone know of a complete unit in good order with a 30 day return policy? I can spend maybe about $200. I will pay immediately and i'm easy to deal with.

Posted by Louis Bornwasser (Member # 3063) on 09-19-2014, 08:53 PM:

65 is better than 45. I do understand the cp-45 and have never had a problem getting wonderful sound out of them. . . . you gotta know the tricks. The 45 doesn't take prisoners.

Posted by Mark Gulbrandsen (Member # 72) on 09-20-2014, 09:29 AM:

Jas Verlin,

With the right cards in it the CP-50 can sound almost as good as a CP-65! The real bad spot in the CP-50 was always the Cat 117 fader card. It had extremely high harmonic distortion at hi frequencies. But you replace it with a CAT 517 card and it's like magic.

Still, in my expereince nothing else older or any current product today even comes close to the sound quality of the Panastereo CSP-1200.

Mark

Posted by Jas Verlen (Member # 8420) on 09-20-2014, 11:09 AM:

There appear to be no Panastereo units on ebay so while it may be a good way to go it is not anption unless i can find one.

As of now i'm still stuck on ebay for a dolby unit and the options don't look good

But thanks to everone for the input and as i said if you hear of a unit in running order in my range pls let me know

Posted by Steve Moore (Member # 4753) on 09-20-2014, 02:46 PM:

Ebay item no 111400169973 looks a good fully loaded CP65, but its showing up as £180 in the UK - not sure what it is in the US, where it is located?

Posted by Jas Verlen (Member # 8420) on 09-20-2014, 04:24 PM:

Yes i am watching thtat one.. It is $300...but i could possibly make a lower offer.

Question - i am looking over the pictures - my Devry has RCA outputs - i dont see where i connect them to on this unit?

Posted by Jas Verlen (Member # 8420) on 09-21-2014, 10:40 AM:

Another possibility might be the FMR RNC (really nice compressor). $150, supported by manufacturer, probably simple to use with exception of non-rca connectors. Seems designed to handle the overly dynamic problem i am having.

Posted by Fredrik Sandstrom (Member # 8171) on 09-21-2014, 11:56 AM:

quote: Jas Verlen
Do you think a dolby cp50 or similar would solve this?

While I agree with everyone that a Dolby processor is definitely the way to go for high-quality sound, I fail to see how it would solve your particular problem. Quite the opposite in fact; a Dolby processor will EXPAND dynamic range during playback, whereas you seem to want to compress it. Or am I missing something?

Posted by Marcel Birgelen (Member # 6801) on 09-21-2014, 04:34 PM:

I guess he's facing the problem that he's trying to run Dolby A and maybe even SR prints without any suitable decoder. That won't sound so hot.

But is this for a home setup or an actual cinema? If you just want to spend 200 bucks on improving sound, it's never going to be hot...

Posted by Jas Verlen (Member # 8420) on 09-21-2014, 05:00 PM:

I have the problem described with all prints - mono or dolby. This is for a home cinema.

Posted by Jas Verlen (Member # 8420) on 09-27-2014, 06:31 PM:

Improved the situation by doing the following:
- reduce sound level on radio shack mixer
- on pyramid amps: inceease midrange a lot, reduce bass a liitle, increase treble a little

Effect is to lower overall sound level but increase voices.

Sound quality is mediocre, but i can hear most dialogue now.

Wonder if the dolby conversion may have polarity issues or perhaps sound lens focus isnt spot on

Posted by Jas Verlen (Member # 8420) on 10-10-2014, 04:12 PM:

All

I have an opportunity to buy another Devry. It looks like it is in good shape but it is original - no solar cells. The owner does not have the matching amplifier.

Question - can i take the output of this unit and plug it into my mic mixer, or does this unit need the original amp to power the old cell?

Posted by Mark Gulbrandsen (Member # 72) on 10-10-2014, 04:58 PM:

You really need to replace the photo tube with a solar cell. And power the exciter lamp from a proper regulated power supply.

Mark

Posted by Jas Verlen (Member # 8420) on 10-10-2014, 06:03 PM:

Perhaps...although the one i have has a solr cell and i'm not terribly thrilled - that's how this thread started to begin with!

Going back to my question - does anyone know if the original phototube requires power from the original amp or whether i can just plug the output right into my standard sound system.

If it requires the original amp to power it, which the owner does not have, there probably isn't any reason to buy it.

Posted by Mark Gulbrandsen (Member # 72) on 10-10-2014, 08:55 PM:

Be sure your solar cell has a low impedance load across it... 600 ohms or less!

Posted by Kenneth Wuepper (Member # 1174) on 10-11-2014, 10:18 AM:

Yes! The photo tube requires a bias voltage to operate. The impedance is very high. That bias voltage was supplied by the original amplifier power supply. The exciter lamp was operated by a high frequency oscillator in most 16mm projectors.

Posted by Jas Verlen (Member # 8420) on 10-11-2014, 11:09 AM:

Thank you Kenneth. I guess if i don't have the amp then the projector can't be used.

Unless someone knows a technician in the Chicago area that could convert it to solar cells as Mark suggests. .???

Posted by Kenneth Wuepper (Member # 1174) on 10-11-2014, 03:42 PM:

Check with the folks at International Cinema NTE as they had some Bell & Howell amplifiers from when they built the JAN projectors. Perhaps one of these would work for your purposes.

Posted by Mark Gulbrandsen (Member # 72) on 10-12-2014, 01:38 AM:

Better yet call James Bond at Full Aperture Systems in Chicago. I am sure he or someone he knows that's also local can help you.

Mark

Posted by Jas Verlen (Member # 8420) on 10-12-2014, 08:53 AM:

Kenneth and Mark - thank you both.