Cheap but not too much !

[guitvinny]

If you have a minute or two that would be greatly appreciated !

I’m searching for a schematic of a amplifier that I can realize without being hungry for the rest of the year . I got around 450 US$ to make this project and I already got my chassis, so it’s 450 on tubes and components.

so here’s my restrictions:

- 2 Channel around 25 W Push-Pull (between 15W and 35W) per channel
- Max 3 tranny, 1 power tranny that power both channel and 2 output (Hammond would be perfect)
- A schematic that show not only the preamp section in Russian, but a complete circuit.
- With easy-to-find tube over eBay.. so no tube from 20`s

I think of 6V6 or 6L6GC would do the thing, but if you have suggestions... you know what to do . Thank you all for helping me!

[Eli Duttman]

Hammond 1650H O/P trafos are approx. 80 USD each. A Hammond 372JX power trafo will do nicely and it costs approx. 95 USD. A Hammond 158S choke that costs approx. 18 USD rounds the "iron" set out.

Use a 5AR4 as the B+ rectifier. Follow with CLC filtration.

Self (cathode) biased and triode wired PP 7591As running in Class "AB1" should get you over the 15 WPC mark. A no NFB design is possible triode wired. Some sort of NFB will be required if you go UL to increase power O/P.

Study the various phase splitter topologies here. The Schmitt circuit with RK2 replaced with a constant current sink (CCS) will work well and does not require a B- supply. You will need a B- supply if you want to eliminate CG2 and (possibly) CG1. A 12AT7/ECC81 as the splitter would allow the amp to function without a preamp. Make RG1 and RG2 560 KOhms. couple the wiper of a 50 KOhm log taper pot to CG1.

[Geek]

A pair of these and one of these with a quad of 6V6 will do you nicely

[guitvinny]

Wow Edcore is for sure real cheat tranny, but does they sound good?
Geek, what about the shipping, if you have any experience with
them ?

For the power transfo is the Hammond 272 JX or the 372 JX will be enough for running both channel ?

By the way take for you input !

[Geek]

You're welcome!

Originally posted by guitvinny
Wow Edcore is for sure real cheat tranny, but does they sound good?

Yes.

With the amp I built that has only 3.5dB NFB, I'm getting 19Hz to 19.5KHz at the -3dB points and I've been listening to it for months now and they sound as good as any I've used so far.

Geek, what about the shipping, if you have any experience with them ?

Yes again. They only charged me exact USPS rate. They also accept PayPal.

Tubelab has a great thread on a review of Edcor and he put them through a lot more abuse than I did.

[Eli Duttman]

For the power transfo is the Hammond 272 JX or the 372 JX will be enough for running both channel ?

Yes, you would have enough current. Both the _72JX and the 5AR4 are rated for 250 mA. A 250 mA. B+ supply will be adequate feeding 4X 7591As and the driver circuitry.