Buffalo III DAC Tube Output Stage

[beau2317]

You could use something like that. I just built a simple thing from a transformer, bridge rectifier and capacitors. DIY is the name of the game

[dirkwright]

Originally Posted by qusp

i would use a couple of common gate mosfets in place of the transformer for coupling the tubes in order to present a lower impedance to the dac. i suppose the same could be said for certain transformers vs tubes? tubes are pretty alien to me so just a hunch.

beau, what cathode/IV resistor value did you end up going with?

@ gillib: are you planning to do an 8 channel tube output stage with the AKD18P? if so, wow thats gonna need a chassis and a half

If he has his heart set on tubes he can use a pair of ground grid tubes directly driving a pair of white followers. I can scan in a sketch... maybe.

[gillib]

Now my DAC is finished. I changed some values at the first tube.

Ra is now 50kOhm, Rs for LM334 is 15 Ohm.

The sound is amazing.

Here are some pictures:







Thanks to Acko, Lorien, Paul Hynes and the great work of Allen Wright (posthumous).

regards
Bruno

[beau2317]

Cool. It always strikes me as kinda funny that there's all this supporting circuitry, and this tiny little DAC chip in the middle, doing most of the work.

Did you have the same DAC with a solid state output stage before? If so, how would you compare the tube version to the SS ?

[gillib]

No, i did not try a solid state output, I enjoy tubes.

Bruno

[tmas]

Gillib,

What tube output stage did you use here?

[beau2317]

I understand it was an Unbalancer as I described in this thread, but he used different tubes - ECC802 and ECC99

Actually gillib, I tried ECC99 and it sounds pretty good, but found the 6H30-pi a bit better. But they are a lot more expensive.

[gillib]

@tmas At the moment I use ECC802 and ECC99. I followed Mr. Browskie's article:

The Unbalancer

I will give the 6H30p a try.
But I think the most important part of the tube stage is the HV Super Regulator (http://www.vacuumstate.com)
You can find the cicuit in 'The Tube Preamp CookBook' http://www.vacuumstate.com/index.tpl...907.3461467244

[beau2317]

Note that the heaters are different on the 6h30. Also they take more current. But I found that the cathode resistors can be the same.

[gillib]

@tmas At the moment I use ECC802 and ECC99. I followed Mr. Browskie's article:

The Unbalancer

I will give the 6H30p a try.

But I think the most important part of the tube stage should be the HV Super Regulator
You can find the circuit in the The Tube Preamp CookBook.