Basically, I have an old suitcase style turntable (I would guess the 60's) will all tube circuitry and a beautiful tone. Other than using a guitar speaker are there any other considerations if I wanted to convert it to an amp? Oh and I do; want to, that is.
amp made from a turntable?
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Jul 24, 2008 10:36 a.m. the_last_unicorn:
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Jul 24, 2008 8:16 p.m. Mark Synchro:
I think I'd be interested in the input impedance that amp was designed for. You might have to do some re-engineering to make it match the output of an electric guitar.
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Jul 25, 2008 12:54 p.m. antik:
I have a tube amp from a 1960's Bogen record player sitting on the shelf waiting for a conversion. From what I recall the input resistance is in the 47K range or maybe it was 68K (Its been awhile since I looked at it). The original output transformer is probably undersized and needs to be replaced. I think the original 12" Jensen speaker (C12R - 15 watts) is the same one used in Ampeg Reverberockets from that era.
Here is a photo of the cabinet.
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Jul 25, 2008 1:14 p.m. BillyZoom:
Does it use a ceramic, or magnetic cartridge? If it uses a ceramic, you'll need another gain stage for guitar. If it has a magnetic cartridge input, you have enough gain, but you'll have to find the RIAA equalization and disable it. Then you'll have to roll off the bottom end a little, but that could be just a smaller coupling cap. ALSO...make sure the thing has a power transformer. A lot of the little suitcase phonos were AC/DC, which means they're really dangerous to fool around with. Don't mess with it if the tubes have big numbers like 50C5, 35W4 etc. They run straight off the 120 volt outlet power, and the chassis is live. You have to use an isolation transformer to work on them.
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Jul 25, 2008 5:04 p.m. mainsoda:
Woah, Billy you're a genius!
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Jul 26, 2008 7:55 a.m. Sid:
I've built a couple amps in the past from tube phonographs, as well as old tube radios. Most had 50C5 output tubes, which give a pure single ended class A output at 2 W max. That means you can overdrive them real nice without blowing your eardrums and with reduced chance of a disturbing the peace summons. But, as BillyZoom said, most of these type amps have a live chassis, so be very careful! I use an isolation transformer anymore when messing with these type amps.
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Jul 26, 2008 10:06 a.m. Proteus:
My first "amp" was a Wollensak tape recorder in my father's home-built hi-fi – which was wired to speakers in several rooms of the house.
Just plugged in and put it in record mode somehow without threading a tape.
Smooooth creamy distortion when cranked above a third of the way up (or so), and I don't suppose it was loud by Marshall stack standards, but I was playing the entire house, so it was good!
I wasn't, and the process of playing the house did help convince Dad I should have an actual stand-alone guitar amp.
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Jul 26, 2008 4:06 p.m. Space Jase:
Lil' Proteus: Dad, I need a guitar amp.
Dad: Just use my hi-fi.
Lil' Proteus: KARANG!
Dad: Let's go to the music store.
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Jul 26, 2008 7:24 p.m. BillyZoom:
The Wollensaks were great for guitar. You can use them as a preamp too. I think every studio musician in Hollywood in the seventies had one.
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Jul 26, 2008 7:26 p.m. Proteus:
I wonder if a Wollensak is responsible for the guitar tone in The Guess Who's "No Time."
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Aug 6, 2008 5:05 p.m. GretschKiller5129:
in 50 years maybe people will play guitar through ipods then ...
