Film-Tech Forum ARCHIVE: Info on IPC AM-1001 amps

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Posted by Doug Eisemann (Member # 782) on 07-09-2001, 11:40 PM:

I just purchased a pair of IPC AM-1001 push pull 6L6 tube amplifiers from a friend and am planning on restoring them to working condition. I checked the manuals section here, and several other internet sources, but have come up with no further information on the AM-1001, which I believe is one of the older, smaller amps that IPC made. It would make repairing much simpler to have a schematic or service manual for these amps. If anyone knows where I could obtain this info, I would greatly appreciate it.

Thanks in advance, Doug Eisemann

Posted by Ken Layton (Member # 133) on 07-10-2001, 12:04 AM:

The amp info you need is already here on the manuals page. Click on the Simplex C-60 sound system. The AM-1001 is a component of it.

Posted by Doug Eisemann (Member # 782) on 07-10-2001, 01:02 PM:

Thanks for the information. I was having trouble downloading the PDF files last night and I must have skipped that one! Now I see it, and everything I need is there.

Again, many thanks.

Doug Eisemann

Posted by Will Kutler (Member # 770) on 07-10-2001, 01:35 PM:

Hi Doug!

I used to subscribe to a audio hobbiest magazine called Antique Radio Classified. There was a guy in there who was big into theater tube amps. Actually, antique audio systems, radios and short wave is a very big hobby!

Vacume tube sound systems are still very popular and are on the high end of the audio market. My Carver C.D. player had vacume tube outputs. McIntosh, Marantz and other vacume tube amps from the 1950s-1960s are considered treasures whose sound quality is still a force to be reconed with. Consequently, they are worth $1000s!

There was a major parts distributor called The Parts Connection who has all the stuff needed to restore your equipment. Porcelain tube sockets, fancy connectors and wiring. Foil Caps etc,etc. New 6L6s should still be aviable.

One design change I may recommend. Conrad Johnson uses both a red and green L.E.D. across each tube to let you know if plate currents are correct. Eliminates the need to align currents on an oscilloscope. They warn that you can tweak the tubes to get a "better" sound, but misaligned currents will decrease tube life.

Also, when running tube amps, cleanliness is very important! Vacume tubes radiate a lot of heat and collect a lot of dust! Dust traps heat resulting in reduced tube life! Enclosed cabinets and towers are also bad for tube amps as they trap heat and dust. On the high-end audio market are "designer" racks that are open, allows equipment to breath! These are expensive, but check them out so that you can build your own. It would also not hurt if you purchased some micro fans from Radio Shack and ran them across your tubes.

Check out some of the hi-end audio magazines,and pay your local hi-end store a visit. Be careful, they can really be snobbish in some of these hi-end audio stores!

Posted by Doug Eisemann (Member # 782) on 07-10-2001, 04:46 PM:

Thanks for the information,

I have been interested in tube audio for a while now, mainly after my experience with working on the sound system at the Newtown Theatre in Newtown PA. They continue to use the original IPC AM-1011 amps there with a solid state Altec for backup. Formerly there were 2 Simplex something projectors and carbon lamphouses, but since one rectifier went bad, they have changed over to Christie xenon, and a platter system, making running a bit more boring. Those IPC amps still continue to perform flawlessly though. I know on amps this age, the electrolytic caps degrade, and should be replaced, and on any older electronics, it is good to power up slowly with a variac. I have a miscellaneous pile of tube amps, including a very nice Western Electric 124D, which I have been told can sound fantastic, and is worth a good deal. I am looking forward to getting a real matched pair of amps up and running!

Thanks, Doug Eisemann

Posted by Will Kutler (Member # 770) on 07-10-2001, 05:29 PM:

Doug,

Get the high end oil filled foil caps.

Also, disconnect at least 1 lead from each of the components and test them to be sure they are ok. Resistors can also go bad over time--and other stuff also. Go to Radio Shack or an electronics store and get electronics cleaner.

Contact the folks at Antique Audio Classified. I believe that the collector I mentioned is in New York(?). Also double check with them about replacement components. I am not sure, but I have been told that sound/performance can change depending on the GRADE of component used, irregardless if the VALUES are the same.

One of the reasons Tubes are popular is because of the smoothness of sound they produce--it has to deal with even and odd harmonic distortion. The differences between transistors and tubes can be seen on an oscilloscope. But many of the high end audio magazines actually present charts and graphs with their reviews.

Wise decision to use the Variac--smart thinking!

good luck!

Posted by Aaron Sisemore (Member # 145) on 07-10-2001, 11:06 PM:

Tubes RULE!!! I have a bunch of tube gear here including two Dynaco ST70's, an Altec 1570B, several no-name miniature amps, a Kenwood KW55 receiver, etc...

One thing to remember: Quality tubes, while harder to find as time goes on is the only way to go. Stick to USA-made 6L6GC's GE, Sylvania, (both still somewhat available but the prices are rising) or if you want to spend the big bucks, RCA blackplates. Avoid the Chinese tubes at any cost,(very poor quality control and extremely short lifespan compared to US and premium Russian types) and the only Russian tubes I can recommend are the Svetlanas. The 'Sovtek' '5881' is neither a true 5881 nor a 6L6, it is a rebased servo amplifier tube with similar (but far enough off to not be optimum) characteristics to a genuine 6L6.

Recapping, as Will mentioned is almost universally required with many 50+ year old tube equipment. Antique Electronic Supply http://www.tubesandmore.com carries many of the twist-lock electrolytics and axial electrolytics that were common back then, as well as thousands of tube types. The Variac is another good idea, if you can get one. An alternative to the variac is to rig up a cord with a 100 watt light bulb in series with the amplifier, and if the bulb dims or goes out upon powering up, its a safe bet that there are no shorts in the power supply transformers or capacitors., Still the Variac is the best way to accomplish this.

Good luck and happy listening

Aaron

Posted by Will Kutler (Member # 770) on 07-11-2001, 08:08 PM:

Here is the address for Antique Radio Classified:

P.O. Box 2, Carlisle, MA 01741.

They also have a web site under their name.

Posted by Doug Eisemann (Member # 782) on 07-11-2001, 08:45 PM:

Thanks for everyones' comments about these amplifiers. I am glad the schematics and wiring diagrams were available on this site. On my particular amps, the original wiring harnesses were cut off, so I have no terminal strips to work from. I think I can get around this by tracing the wiring out and building bases for the amps with new terminal strips and RCA connectors. This will avoid having to drill holes in the chassis or remove original wiring (I should be able to use it provided that it is not overly brittle and I can wire it to terminal strips) I also must safely terminate the unused wires that supplied filament and plate voltage to the preamp modules. I also have a 1000W industrial variac that I was given that will work excellently in this situation. (an ancient Western Electric affair that also needs some cleaning up, but should come in handy)

Posted by Will Kutler (Member # 770) on 07-11-2001, 09:22 PM:

Contact the Parts Connection or Antique Electronics Supply. If you want to spend the money, then they have all types of hi-end wire and rca connectors, and other goodies! Be careful. Some of that old wiring may have cloth or real rubber insulation that may be no good. Get quality wire from them. New components such as gold plated rca connectors will not corrode or tarnish. If you choose to keep the old wiring, then be careful on how you go about cleaning it.

One of the fanciest pair of home audio amps that I saw advertised on the new market was as follows:

Each channel had a seperate chassis. The power supply also had a seperate chassis. The chassis were all granite w/insulating feet. All hand wound solid silver wired transformers. All solid silver hand soldered wiring. Porcelain tube sockets, etc,etc. Cost about $100,000.

Remember, audio systems of yesteryear were very efficient. They only needed 15-50 watts to power speakers. I had a friend who had a very low wattage and very efficient sound system that could blast the hell out of any high wattage system today--beautiful sound and no distortion!

The difference between hi-end audio and mainstream audio. Hi-end relies on hi efficency and hi quality components, manufacture and design. The philosophy is to get the sound from the source to the speakers as directly as possible. Hi-end systems (amps) only have an on-off switch) Pre-amps have a volume control, radio, c.d., l.p, tape selection and maybe a trebel/base switch. Rarely do you find any type of complicated equalizer in hi-end systems!

Many people think that hi wattage makes the system. This is

Check out some of the hi-end magazines and stores. The only thing that I hate about these folks is that they can be very snobbish, or so my experience has been!

Happy listnin'!

Posted by Doug Eisemann (Member # 782) on 07-11-2001, 09:39 PM:

Hi again, I very much agree with you on the low wattage/high efficiency speaker comments. The AM-1001's only put out around 15W, but when coupled with efficient horn speakers such as Altec A7 voice of the theatres, you can obtain incredible, gorgeous sound with only a few watts. The current trend in mainstream audio is more power=better. True, these old speakers were designed with high efficiency since amps were not all that powerful until the mid to late 50's, but there is something about the issue of quality over quantity. One does not even have to rely on old speakers to accomplish this, there are many high end modern speakers with high efficiency, and some excellent sounding professional speakers, that, while they can handle large amounts of power, have efficiencies making them excellent for low power tubes. I would really love to see for example, how some of the excellent sounding Bag End speakers, at over 100dB efficiency, sound when driven with tubes. Certainly, they can be blasted with mega-amps, but they might really sound sweet with modest tube power. One must also watch when you say you are using old theater amps when talking to snobbish high end audio salesmen!

Sorry for my ramblings, Doug Eisemann

Posted by Will Kutler (Member # 770) on 07-24-2001, 04:46 PM:

FYI--check out the Western Electric web site! Also, there is a web site for stereo classified---check out the prices of some of this stuff!! Western Electric 300B tubes are now being made again--watch out for those prices for a matched pair!! A pure audiophiles dream!!