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Starving Student PCB's - Page 7

post #91 of 225

I mean that you still need to wire the outside dc connector to the PCB  

post #92 of 225

Our PCB's ae stuffed and mine is set up for 12au7 and 24volt supply, sounds very good. Wes is doing a 48volt version ans his supply is still not here.

post #93 of 225
Quote:
Originally Posted by eroline View Post
 

Our PCB's ae stuffed and mine is set up for 12au7 and 24volt supply, sounds very good. Wes is doing a 48volt version ans his supply is still not here.

Did you change any components' value when using 24v? 

post #94 of 225

The output fets needed a new bias setting to ensure 12 volts to the heaters.

I left c7 and c8 off , used 1000u caps for B+ bypass ad to couple to the output. That should improve the low end.

12BH7 tubes can be used to run at 300ma for lower impedance cans, but larger heatsinks are necessary. I did a variant design using 12au7's as the differential input pair, with silicone opamp biasing, "Sand in my Glass project. uses the heater current for fet pull down so it also is black hole quiet, no hum. I left the heatsinks so they could be soldered or screwed to the PCB to secure them. 1/2 heights work well for 24V 12AU7 combo, full heights would be necessary for 48volt or 12BH7 combo. The PCB was toner transfer etched in a ziploc bag.

post #95 of 225

R2 was changed to 73k  to help account for the VGS of the mosfets chosen. 73k pull up to 24 volts and 220k pull downs to neg. gnd

post #96 of 225

PM Sent

post #97 of 225
As a complete newb to this stuff, and having a PCB on the way, does anyone have a complete BOM for this build? Possibly with upgraded components?


Thanx!

-Xander
post #98 of 225

Are these still available? if so i'll take two.

 

Thanks!

post #99 of 225
Thread Starter 

Drop me a PM with your email and address

 

cheers

FRED

post #100 of 225

I just caught this thread. Did i read you say 3" x 3"? I can't resist the must have. May i send a pm?

post #101 of 225
Thread Starter 

Yes 3" x 3" :-)

 

drop me a pm

 

cheers

FRED

post #102 of 225

Just finished my build and WOW loving tube sound. This is my first experience of the sound of vacuum tubes and I love it. I'm using DT770s and to me they feel like they've 'opened' them up. The sound is much more like an open back headphone sound now. Brilliant, thanks Fred!

post #103 of 225
Thread Starter 

Glad you like it, they are a very simple build for a surprisingly good sound :-)

 

cheers

FRED

post #104 of 225
I already have an O2, makes sense to still get this? Does this have tube like sound or more SS like sound?
post #105 of 225
Quote:
Originally Posted by doors666 View Post

I already have an O2, makes sense to still get this? Does this have tube like sound or more SS like sound?

 

Tubey. It has rather high distortion but mostly 2nd and 3rd, so it sounds rather euphonic. See http://www.pmillett.com/starving.htm

 

 

That's the price for running valves at lowish voltages but it makes for an amp you're never tired to listen to.

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