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Henry Scott Yocum Memorial Amplifier Build


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After some deliberation, and since this amplifier has no headphone output, I ultimately decided that the slight lowering of the noise-floor by using DC heating on the driver tubes wasn't worth the sonic trade-off, and, since this custom power tranny has separate 6.3v windings (one for each channel) I used AC heating with virtual center taps as per usual. This pic shows how I typically leverage the space below the power transformer to mount connection points for power supply wiring/DC rectification (when necessary). 

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In the pic you can also easily see both the "slow-start" MOV and Class X "pop-stop" capacitor as typical on amplifiers using a directly-heated rectifier.

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As much wiring is completed as possible prior to building the "turret-board" that is suspended above the front section of the amplifier. This turret board is where all of the circuit connections are made to the devices that are soldered to the tube sockets. I build mine out of 1/8" fiberglass board and individually "swage" each turret using a press I built for this purpose. Doing this rather than buying "tag strips" or pre-made turret boards allows me to design the layout and connection points EXACTLY where I want them with no waste. A pic of the board layout I developed for Scott's amp (and all Euphoria 2a3's coming up) will be attached to the next post...... this one is yelling at me about max file size...

 

As I sit here typing, I'm amazed at the SQ of this amplifier.... another bonus, although I designed this amplifier to maximize the sound quality of the 2a3 output tube (my favorite operating points using a 5K primary OT), by dropping in a 5R4GY rectifier, this amp is perfectly safe for use with the "45" output tube. It sounds glorious on this last day of burn-in driving my Cornwall 3's with a very, very old pair of engraved-base Philco 45's. :)

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I know nothing about the inside of an amp but I do know if anyone deserves this it would be Mr. Yocum, one of the nicest people you could ever meet.

 

Here with good friend Steve, two great guys. 

 

Thank you for Memorializing him like this, he is smiling.

pilgrimage_2018-080.JPG

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Here is the plate (gut-shot) mounted in the wood base...... as you can see, enough room to work but not much else. ToolShed Amplifiers are only as large as they have to be.IMG_2290.thumb.JPG.d1d2a845c15599ba10b5719893783791.JPG

 

I've designed the amplifier to have the coupling capacitors easily accessible should customers feel the need to "roll" those too.... :)

 

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Top-side of the amp prior to wiring and installing the front and rear plates.

 

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The last photo's I'll post will be the ones I take today after the bottom plate is installed (post burn-in) in preparation for shipping this evening. I've really enjoyed my time listening to this amplifier during burn-in and can say without reservation that my Cornwall's have never sounded so good. At least until the next one burns-in..... ;) 

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On 12/19/2018 at 1:17 PM, dtel said:

I know nothing about the inside of an amp but I do know if anyone deserves this it would be Mr. Yocum, one of the nicest people you could ever meet.

 

Here with good friend Steve, two great guys. 

 

Thank you for Memorializing him like this, he is smiling.

pilgrimage_2018-080.JPG

I had a few opportunities to talk with Mr Yocum at the last pilgrimage and remember him as a very nice person.

 

miketn

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22 hours ago, mikebse2a3 said:

@ToolShedAmps  Thanks for all the effort and work you did in showing us how you build your beautiful amplifiers.

 

miketn

 

Thanks Mike! The Yocum family should have it either today or Monday at the latest. Perhaps they will listen to some holiday music through it. Thanks for following along..

 

Cheers All! 

 

Matt.

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