About tube DACs?

[hpeter]

I have not went trough whole thread yet (sorry), came across one idea i had ago
since some advanced dac constructions uses external clocks (txco,rubidium stuff..), those often can´t be used straight, frequency has to be somewhat changed
it made me thinking, why not to use tubes also in PLL clock subsystem....

1)use tube it as simple xtal osc (+ use heat from tube for xtal, + low rpm fan with temp sensor glued to xtal *optional*) (gum-like thermal pads..)
2)use tube as LC osc in PLL divider/multiplier
of course, everthing else would be done by chips

ecc88 was designed for rf anyway

 

[AudioLapDance]

Whaaat?!? A long thread on tube DACs and no one references the consummate DIY piece about tubes and a variety of DACs by Thorsten Loesch?!?

Updated:
Thermionic Valve Analogue Stages for Digital Audio - A Short Overview of the Subject by Thorsten Loesch

(can't figure out how to download and repost ...)

And the original:

http://www.raylectronics.nl/pdfs/Thermionic_Valvestages.pdf

View attachment Thermionic_Valvestages.pdf

An Old-School classic!

 

[Blitz]

Thanks,
The unbalancer seems to be a remarkable circuit compared to the traditional differential parafeed.
How is the balancer and the I/V resistor (value?) connected to your buffalo ?

Well...if you use normal mode, you need 50ohm as grid to ground resistor which does the i/v conversion, otherwise you simply connect the biii withthe unbalancer. If you use dual mono, 20 ohm is enough. In dual mono, you need to be aware how you connect the unbalancer correctly, there is a specific cabling required to sum up correctly:

"Ok so lets start with some definitions:

OSR = output stage for balanced right output
OSL = output stage for balanced left output

Choose which input on each output stage you want to be +(normal phase) and which will be -(inverted phase). They are marked on each output stage board as "dac input left" and "dac input right", for this example I will assume you use "dac input left" for in+ and "dac input right" for in- on each board. From now on I will refer to those an "in+" and "in-" respectively.

For the left channel configured Buf 2 you will wire DAC outputs to output stage inputs like this:
Left + and Right - (both joined in parallel)to OSL in+
Left - and Right + (both joined in parallel)to OSL in-

For the right channel configured Buf 2 you will wire like this
Right + and Left - (both joined in parallel)to OSR in+
Right - and Left + (both joined in parallel)to OSR in-

Of course you should connect GND to each output stage input GND as well.

Your situation is different from IVY-III and Legato 3.1 (and the apps for TI and Wolfson) because the signals are not run through a differential amp (which helps with DNR by canceling common mode signals).

I truly hope that helps. If you still have questions its ok, ask away.
Edited by user about a year ago | Reason: Not specified
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