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August 11, 2020, 12:10:19 AM

Author Topic: Help identifying Bottlehead preamp & rectifier  (Read 6738 times)

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Offline iLikeSound

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Help identifying Bottlehead preamp & rectifier
« on: December 09, 2016, 07:31:38 AM »
Hello all,

New here. At some point I'll buy and build a kit. In the meantime:

I recently bought (via craigslist) a Bottlehead preamp. Hoping you could help tell me which one it is (or if it's a FrankenHead). The small tubes are both 12au7.

I also can't identify the rectifier. The base says RCA Electron Tube, and has Made in USA, and 3-39. The internal parts look interesting to me: The upper and lower spacers are toothed, like a bike cog, and the plate is cylindrical. It glows blue.

Pictures below. Thanks in advance!


Offline Natural Sound

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Re: Help identifying Bottlehead preamp & rectifier
« Reply #1 on: December 09, 2016, 07:46:28 AM »
Thats a Foreplay III. The "regulator" is an 0D3, 150V regulator. The rectifiers are solid state. Does it work OK?

Offline iLikeSound

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Re: Help identifying Bottlehead preamp & rectifier
« Reply #2 on: December 09, 2016, 07:56:57 AM »
Thanks a lot - that was fast!

Yes, it works fine. Sometimes I need to wiggle the input cables a little to get one channel to work, but I'll clear that up as soon as I open it and check the solder connections.

Will changing the regulator (to a different brand, or a different type) affect the sound much (or at all)?

« Last Edit: December 09, 2016, 08:04:12 AM by iLikeSound »

Offline Natural Sound

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Re: Help identifying Bottlehead preamp & rectifier
« Reply #3 on: December 09, 2016, 08:04:27 AM »
I never found regulator tube rolling to have an effect on the sound.

Offline Doc B.

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Re: Help identifying Bottlehead preamp & rectifier
« Reply #4 on: December 09, 2016, 08:29:13 AM »
It looks like it uses the basic Foreplay III circuit and probably one of our power transformers. But it's not a Foreplay III factory chassis. So yes, it is in some ways a Frankenstein.
Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.