• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

EL34 Baby Huey Amplifier

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Joined 2004
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Hello Prasi,

I finally recover my last PCB (my Lenovo AIO did not work anymore, but the hard disk is OK ?) and corrected the errors found by snapper :)

I also added a jumper to use the negative input for the feedback or a differential input version...

I am also working on some cosmetic change.

Cheers,
Marc

Let’s not forget the TENA amplifier that Marc did not build (see post #826) Perhaps it could be a memorial to him.

https://www.diyaudio.com/forums/att...182310-el34-baby-huey-amplifier-kt120-sch-pdf
 
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Yes that's a real sad thing about Marc, such a loss.

As for the relay. I looked for one as well when I built mine, could not find anything I was satisfied with, so installed the specified one from the parts list. I fully expected it to fail, if not quickly at least over time.

Almost a year later, I use my amp almost every day as it's in a workout room that we use all the time. It gets fires up almost every day, some times two or three times per day.

I'm glad to say I have not had any problems with the relay! Not to say that it will last forever, it could go next time I turn it on. But I have been surprise so far at how flawlessly it has worked.

Maybe Marc knew something we don't know. He actually knew a lot I don't know, but that's a different story. RIP

gabo
 
Very sad news. RIP Marc.

Not to dismiss this loss, but I’ve seen a lot of talk about the relay and wondered if there is a consensus on a sensible one? I’m starting to collect parts and need to put in a fairly large order to Mouser.


I preferred to play it safe and I mounted a high voltage relay adapted from Te Connectivity ref: 2-1904058-7 but you have to replace the 2n3906 transistor for a more powerful one like the BD140
 
Well I just tried the modification with the BD140 transistor and it works perfectly to drive the relay. More than to mount the transistor on a small radiator
 

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