[Kaaf]

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

 

[eroline]

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.

 

[RealSpark]

  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? 

 

[eroline]

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.

 

[eroline]

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

 

[mburgess00]

PM Sent

 

[fast14riot]

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

 

[kchapdaily]

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

 

[Fred_fred2004]

Drop me a PM with your email and address
 
cheers
FRED

 

[Sunshine55]

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?

 

[Fred_fred2004]

Yes 3" x 3"
 
drop me a pm
 
cheers
FRED

 

[HighMasterGogo]

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!

 

[Fred_fred2004]

Glad you like it, they are a very simple build for a surprisingly good sound
 
cheers
FRED

 

[doors666]

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

 

[00940]

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.