1212 OTL-20 Manual/Operating Instructions

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baileyler

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1212 OTL-20 Manual/Operating Instructions
« on: 8 Dec 2010, 04:04 pm »
Does anyone have a copy of the manual or other operating documentation for this amp (or just working knowledge I can tap into)?

I would ask 1212 Designs, but they seem to have shut down (although the website is still up).

Also, has anyone heard of a potential design defect in the protection circuitry?

Thanks in advance.

Wayne1

Re: 1212 OTL-20 Manual/Operating Instructions
« Reply #1 on: 8 Dec 2010, 05:46 pm »
You might want to send a PM to mgalusha.

I believe he has a pair of those amps.

mgalusha

Re: 1212 OTL-20 Manual/Operating Instructions
« Reply #2 on: 8 Dec 2010, 05:52 pm »
I have the 100WPC stereo amp they built and the manual that came with it. I saw the little mono's for sale on audiogon earlier this week and they appear to just be a smaller version of the same thing. I can make a copy of the manual if you like, it does have some schematics and other information.

I did contact the guy who made them looking for more info when I first acquired the amp and he didn't really have much to say but I might still have his email address.

Ah, just looked at their website and the one I have is the OTL-20, so the manual I have is applicable.

edit - I forgot to mention, I never had any problems with the protection circuit. I did trip it once when cranked up, blew a fuse but had no blown tubes afterwards. One thing I did notice what the B+ voltage is a bit high for the 6AS7G tubes, so I added a larger resistor between the cap banks. This dropped it from about 170V to about 150V if I remember correctly.

mike

baileyler

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Re: 1212 OTL-20 Manual/Operating Instructions
« Reply #3 on: 8 Dec 2010, 06:56 pm »
Mike,

PM sent.

Appreciate any help you can provide.

Bart

BTW - I forgot to mention in the PM that I communicated with an owner of one of these (probably a former owner at this point) that said his unit caught on fire due to a failure of the protection circuit (after he pushed the unit hard).