so i get common tubes free... now i just need a project

[VictorG]

Thanks for the continued help.

I am almost done assembeling the parts list and things are looking good.

I want to include you in my thinking through, just to double check, the particular hammond i was thinking about using was the 1650F

Specs:

1650F
Audio Watts (RMS) 25
Primary Impedence: 7,600 ct
Max DC per side 128 ma.
Secondary Impedence(s) 4-8-16
"these transformers include 40% screen grid taps for Ultra-Linear operation"

The only reason I am double checking this transformer with you is that y your comments yo seemed to be pretty close to commenting on this peticualr tranny save tat you thought the primary impedence wouldbe 3.5k and you didnt think there was a secondary impedence of 16 avail. Were you looking at another tranny that I am unaware of, or did i just read to much into generalized statements?

Anyway, this transformer is in my range, not bad at all pricewise.

Thanks for the continued guidance. I am going to begin a pcb layout soon (just makes it easier for me)

Brian

[Jax]

7.6k impedance is a little too high for EL34's unless you are going to run them in class B with 800V plate

1645, 1650K or 1650N would be better. If money is tight, go for 1645.

[VictorG]

Jax-

You'll be happy to know (or at least I am) that i have aquired around 75% of the nessesary parts.

Now for the power supply-

Any thing I should know, or just get the votage through the bridge rectifyer and put some caps in parallel? Let me know what I should do here, as i dont see any info on this componenet of the system.

Thanks,
Brian

[Jax]

As a starter, for the 350V supply:

280-0-280V AC to a fullwave rectifier with 2 1N4007 diodes, a 22uF 450V cap, a 10H choke and a 100uF 450V cap forming a CLC pi filter.

or:

300-0-300V AC to a 5AR4 or GZ34 rectifier tube, same choke and capacitors above. You need a 5V 2A winding for the rectifier heater also.

You can use a 5U4 rectifier tube also but you need 320-0-320V and 5V 3A.

This is for one channel. If you want to share for both, go with the semiconductor diode version.

[VictorG]

real quick, c11 on the schematic is missing a value. rating? Thanks a bunch, almost there.
B

[VictorG]

where would you recommend an output level control? 100ohm pot where? thnx again.

[Jax]

You can leave C11 out for the moment, it's only needed if you increase the feedback.

You mean a volume control? Just add a pot at the input.