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The Newest Escapee from the Lab (Dumont/HK/Hammond)

GordonW

GordonW

Speakerfixer
Subscriber
Well, it's up and running. And doing very well, thank you. :thmbsp:

dumont-hk 6v6 lf.JPG

This amp is based on a Dumont console amp chassis (that Pete, from here at the store, literally found in a console by the side of a street and rescued from impending rainstorm), but completely re-wired inside. Originally, it was a PPP 6V6 power amp; now, it's a PP 6V6 integrated amp, using Hammond organ output transformers, a Hegeman-style (HK A300) amp circuit, and my new pet favorite 6CG7 preamp.

dumont-hk 6v6 front.JPG

It's pretty overkill... DUAL 5V4GA rectifiers, among other things. But, it REALLY does image focus well... maybe as well as I've ever heard. It doesn't have big power (but, it will drive 90dB sensitivity speakers quite well), but it's got OUTSTANDING dynamics and tactile feel.

I have to say, I'm pretty happy with it. Especially the cosmetics. A good satin-black lacquer finish, with stained oak trim. Simple but effective...

dumont-hk 6v6 rf.JPG
Time for the next one to start going together on the bench, now! :banana:

Regards,
Gordon.
 
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Beautiful amp there Gordon, did you use the dual recs because you have two set of 5V outs from the transformer????
 
Nice work!!

Those Hammond organ OT's do a pretty nice job in audio applications.
I salvaged a couple of working Hammond organ reverb amps, for a similar purpose.

Steve
 
djnagle said:
Beautiful amp there Gordon, did you use the dual recs because you have two set of 5V outs from the transformer????
Click to expand...

Right, pretty much. Actually, it was a single 5V output, but had dual 5Y3s (wired in parallel) on that output, in the amp (with the same power transformer, naturally) originally.

A pair of 5V4s draws the same heater current as a pair of 5Y3s... so it was an easy swap. Got me about 30v more B+.

In fact, if someone were so inclined, you could actually put in a pair of 5AR4s. They also have the same heater draw (2 amps per tube on the 5V line) as the 5Y3 and 5V4. TOTAL overkill... but even then, the B+ would be within acceptable specs for the tubes (the original Harman amp used up to 355V; the highest B+ in mine is 340V now), and the bias would still be within acceptable current limits per tube, on the 6V6s...

Regards,
Gordon.
 
The Conn PX I have has two sets of 5v outs so I am spliting L and R right out of the PX but using the same HV for both, at 350v, so a semi mono power supply.
 
i've got to hand it to you, gordon. between this and the pilot/stromberg circuit you did, you make some beautiful amps.
 
gearhound said:
Nice work!!

Those Hammond organ OT's do a pretty nice job in audio applications.
I salvaged a couple of working Hammond organ reverb amps, for a similar purpose.

Steve
Click to expand...

Do you happen to have a derelict AO-44 chassis? Even without an OPT? :scratch2:

Will PM you...

Regards,
Gordon.
 
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