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Author
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Topic: What Is This Amp?
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Bruce McGee
Phenomenal Film Handler
Posts: 1776
From: Asheville, NC USA... Nowhere in Particular.
Registered: Aug 1999
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posted 12-26-1999 09:50 PM
I just received an International Projector Corporation amplifier.The type is NP11, (serial # 210) It uses a pair of 2A3 outputs, a pair of 57 preamps, and a 5Z3 rectifier. Any idea how old this thing is, and where I might find a schematic for it? I am going to restore it, I hope. I want to say this thing is from around the mid 30's, but I dont really know. It is in beautiful condition, and heavy. Other than tubes, it appears to be all original. It was manufatured for IPC by the Electro Acoustic Products Company of Fort Wayne, Ind. Happy birthday to me today. #43!
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Erich Loepke
Film Handler
Posts: 43
From: Ft. Worth, TX, USA
Registered: Sep 1999
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posted 12-27-1999 01:30 AM
With the tube line-up you gave, this puts it in the mid 30s like you guessed. The 2A3 tubes are still in production overseas for audiophile amplifiers. The others are available from antique radio parts dealers from new old stock.The power output from a pair of 2A3s is around 15 watts. Of course this was considered adequate at the time, and with the efficient speakers being used then, it could achieve loud sound levels. You could try posting this on the electrical/mechanical forum on www.antiqueradios.com The guys there may have a schematic laying around or at least give you some advice on restoring this amplifier. Good luck with your amplifier!
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Bruce McGee
Phenomenal Film Handler
Posts: 1776
From: Asheville, NC USA... Nowhere in Particular.
Registered: Aug 1999
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posted 05-20-2000 09:10 PM
I brought this subject back to the head to say that the amp is now finished and working. Major thanks to Dick Prather for the similar RCA manual that he found and copied for me at no charge, and Ken Layton for steering me to Mr. Prather!The amp runs well and is being used as a monitor amp for now. I am not going to use it with the Holmes! I got lucky with the 2A3 tubes. The one that came with the amp was good. The one I found in my junk box was within 2% just as good as the other one on my tester. I replaced the 57's because the amp HOWL'd when I tapped them. The original 5Z3 was fried when the caps shorted, and I got lucky there, too with another surprise from the junk box! I'm glad I could bring this old beauty back from the dead. It's a real work of art, and they dont make 'em like this anymore. Bruce
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Bruce McGee
Phenomenal Film Handler
Posts: 1776
From: Asheville, NC USA... Nowhere in Particular.
Registered: Aug 1999
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posted 05-21-2000 04:32 PM
Ken:Naturally, my 2A3's are RCA and National Union. Many years ago, we bought a house where the previous owner had left hundreds of new in the box tubes. There were things like 807's, 2A3's, 1625's, 1629's, etc. I had nothing that used these tubes at the time, so, I---gave---them---away. The guy I gave them to kept them until around 2 years ago, when he sold them to Antique Radio in Tempe. Thats when I found that they had lots of tubes. I could kick myself for not simply keeping them in my own garage like he did.
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Bruce McGee
Phenomenal Film Handler
Posts: 1776
From: Asheville, NC USA... Nowhere in Particular.
Registered: Aug 1999
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posted 05-21-2000 08:12 PM
I wanted to maintain the original look of the amp, so I did just what you said. I installed all the electrolytics below, and left all the original stuff showing on top.When the amp is running, the 2A3's, and the 57's have a slight blue-ish glow that pulses to the signal level. I suspect that they are a bit gassy, but its not enough to cause problems. The 2 new 57's are matched RCA NOS from the '30's! They sound vastly better than the originals did. The amp looks really nice in the dark. I wish you could see it. I have a Hammond M-100 that was given to me, too. It had blown the rectifier tube, and all I found wrong was shorted caps. It has a nice sound, too. I'd love to have a Hammond with the 2A3's. Bruce
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