6V6 PP under construction - pics

[gary f]

Hello

I'm building Poindexter's 6V6 push-pull amp.
It is my second DIY tube project,
and the first one was Bottlehead Foreplay II kit.

You can find all the info about this circuit here:
http://www.audiotropic.net/realIndex.html

The best move I did was to buy a IAG chassis from "parts connexion". (No commercial interest involved!)
I'm not equipped with much tooling, so the chassis was problematic to me. But the IAG is very nice with thick plates of shiny inox and very solid. And very much nicer than I would have done.

F

[gary f]

The exterior is now finished. I'm doing the wiring inside.

F

[Sherman]

Very nice! I like your clean organized layout. Please post pics of the guts when you can!

[amperex]

Based on the same design, I use PPP 7C5s that is a 6V6GT in loctal sockets on a monoblock chassis design. Following upgrades includes:

>5R4 rectifier
>MagnaQuest audio iron
>Raytheon 6CG7 tall black plates
>LCLC power supply with oil cap on the output + another LC to the 6CG7 with a 50 HY plate choke.

I use the -140 to the 6CG7 cathode & -25 volts fixed bias to the 7C5s with 325 volts on the plates. Rest of high-end parts are Mills, Vishey & AuriCap.

After testing a dozen or so 5965s, 6922, 12AV7, E80cc 'pinch waist', ECC85 etc, the 6CG7 (Raytheon only) is best.

6CG7 needs a preamp though.

Best higher gain tube in this circuit that does not need a preamp are Telefunken ECC85/6AQ5.

[rdf]

Hi amperex, are those Hammond organ chassis?

[amperex]

Yes, Hammond model G.

I added a pair of 200 ohm @ 12 watt resistors from transformer HV secondary to the 5R4 plates to keep B+ voltage within reason. The first original choke replaced with a new Hammond rated at 5HY @ 200 ma. Replaced the original audio transformer with MQ. But, those original audio transformers are suppost to very good & have cathode windings like some expensive McIntosh iron.

I will complete these amps with wood trim.

[AudioGeek]

i would turn the power transformer by 90 degrees. This is close to your outputs and may cause hum if you do not do this.

richard

[rdf]

That answered my question about the Hammond OPTs. They've been written here as you describe, which had me wondering if you replaced them for performance reasons. Thx for the new 'favourite search' for the E-bay account!

[amperex]

I never auditioned the vintage Hammond transformers. I had a pair of new MQ spares & installed them.