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Old 17th April 2003, 01:28 AM   #1
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Default My new tube DAC output

Here my new tube voltage gain stage for my new DIY DAC. It is using a HV 6X4 Tube rectifier and a double triode Svotek 6922. The 6922 is using DC filement voltage using schottky rectifer and LM317T regulator. The HV is filtered using a CLC filter with two 47uF cap. an a Hammond 9H, 40ma choke.
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Old 17th April 2003, 01:31 AM   #2
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Default Coupling caps

And I just forgot. I'm also using in the signal path all copper Riken resistors and the very good Jensen copper foil and silver lead.

I will listen to this beauty soon...

Comments are welcome. Any suggestion on my tube choice will also be appreciated.

Don't be too hard on me, it is my first tube circuit. Better late than never.

Bye...
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Old 17th April 2003, 01:42 AM   #3
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Default And a few measurements

Since the DAC is not completed, here a few measurements to test everything:

Bandwidth (0.767V, 1Khz reference): 20Hz-300Khz in 50 Kohms

Voltage Gain (in 50Kohms)
0.5Vin = 22.5
31.6mVin (Vout=0dB) = 24.2

Distorsion (in 50Kohms, Vout 0.767V)
100Hz: 0.5%
1Khz: 1.2%
10Khz: 1.4%
20Khz: 1.5%

Are these values of distorsion typical or an other tube brand can give me better values?
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Old 17th April 2003, 02:45 AM   #4
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Default Re: Coupling caps

Quote:
Originally posted by Algar_emi
And I just forgot. I'm also using in the signal path all copper Riken resistors and the very good Jensen copper foil and silver lead.


You know that those caps have outer foil marked and I found that when outer foil is directed towards the load, it sounds better.
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Old 17th April 2003, 12:19 PM   #5
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Default Cap direction

I was wondering I to connect them. Thanks Peter for the tip...

SB
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Old 17th April 2003, 12:25 PM   #6
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The outer foil is marked with a line.
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“Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC
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Old 17th April 2003, 12:41 PM   #7
mig-ru is offline mig-ru  Russian Federation
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Algar_emi,

That looks awesome! I think I might just try tackling a DIY tube DAC. Where did you get the schematic for it, would be interesting to look at.
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Old 17th April 2003, 01:01 PM   #8
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I dont know the exact Engineering on those caps but its almost like they are polarised like an electrolytic cap and what peter has said seems to be true....and to comment on your distortion levels....isnt that what your looking for in a tube design?????....that does make the nuiance warm and proprietary with a tube design.....Live music is never perfect and audiofiles are ultimatley trying to re create a live performance not a mixed studio version


Cheers!!The DIRT®
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Old 17th April 2003, 01:34 PM   #9
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Default tube dac

Excellent. All done on a R.S. project board!
I' d like to know about that ceramic 6dj8 tube socket.
Also evrything you know about the 1/v conversion at the output of the dac. (impedances, levels) this area still confuses me a bit.>>Doug
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Old 17th April 2003, 08:09 PM   #10
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Default Tube socket

I got them from www.partsconnexion.com in Canada. They have gold plated pins also.
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