Please critique my schematic

[Gaz]

Hi all,

This design was originally based off the "October" from the AX84 site, which is similar to a Marshall Plexi. It's been tweaked to my heart's content, and I would greatly appreciate any advice, opinions, or mistakes in my drawing. It's really my first schematic, so don't be too cruel

http://img189.imageshack.us/img189/2695/schem3.jpg

Thanks a ton,


Alex

[Merlinb]

Now why does that look familiar?

The only thing I would add is a couple of smoothing caps to the wipers of the bias pots. Not essential, just good practice.

[Gaz]

Haha! I have posted this on three forums now for review, and was hoping you'd run into it. Between your site and book, I've gathered at least four design ideas I'm using on this amp. Thanks so much for looking it over. I couldn't have done it without you!

I'm not familiar with the smoothing caps on the bias pots. Could you point me to a design that uses them? How might I determine their value?

Thanks again,


Alex

[Merlinb]

I'm not familiar with the smoothing caps on the bias pots. Could you point me to a design that uses them? How might I determine their value?

Alex

Just pretend that the top half of the pot is a dropping resistor, just like you have used to smooth the bias supply. Any old value will do, something in the range of 10uF to 100uF I guess.

[Gaz]

Thanks for explaining that.

I did have another question after re-reading the part in your book where you talk about adding a poly cap across the heater of 'the first valve' to filter out high frequency buzz.

I had assumed you meant first valve coming off the heater supply, but now I think I may have misinterpreted it, and you were in fact talking about the first preamp valve. Please let me know if you get the chance.

Thanks.

[Merlinb]

I had assumed you meant first valve coming off the heater supply, but now I think I may have misinterpreted it, and you were in fact talking about the first preamp valve.

I meant the input valve, but it's not critical.