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Old 1st March 2013, 03:32 PM   #2541
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thanks for the info , is there a special value for the grid leak resistor when you go direct coupling to a 26?
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Old 1st March 2013, 04:23 PM   #2542
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what are you using for attenuation ?
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Old 1st March 2013, 04:36 PM   #2543
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i have some carbon pot, LDR, wire wound 10 turn pots to use as volume pot ..
don't you think it will be better to put it on the Amp side to attenuate the noise frome the 26 and drived by the line output transfo than put it between the dac output and 26 and having to deal with DC on the pot?
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Last edited by juanitox; 1st March 2013 at 04:39 PM.
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Old 1st March 2013, 04:58 PM   #2544
regal is offline regal  United States
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Quote:
Originally Posted by juanitox View Post
i have some carbon pot, LDR, wire wound 10 turn pots to use as volume pot ..
don't you think it will be better to put it on the Amp side to attenuate the noise frome the 26 and drived by the line output transfo than put it between the dac output and 26 and having to deal with DC on the pot?
Yes , but usually you would put the attenuator before the pre not the amp by DC coupling to the DAC you are making what I would call a powerful DAC with a #26 output. I would think you want a low grid leak so as to prevent the #26 grid from damaging your DAC maybe even protection zeners? Some DAC's are sensitive to a voltage other than thier own.
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Old 1st March 2013, 05:08 PM   #2545
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not mine , it"s a resistor base dac ( TOTALDAC) so i think i would have no ptoblem from this side . the only drawback of this dac is that it have an opamp as buffer, i have tried a B1 buffer, sounds better but i'm a tube guy , so i would think a DHT output could be smart enough.
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Old 1st March 2013, 05:13 PM   #2546
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resistor base you should be fine, sounds like a nice DAC integration
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Old 1st March 2013, 05:24 PM   #2547
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the only problem is too much choice avalaible with the 26.
choose your flavor?

1. DAC ...Cap.. battery bias CCS Cap
2. DAC ...Cap.. battery bias 10K/600ohm transfo
3. DAC... dc coupling, filament bias, CCS Cap
4. DAC... dc coupling, filament bias, 10K/600ohm transfo
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Old 1st March 2013, 05:36 PM   #2548
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the only problem is too much choice avalaible with the 26.
choose your flavor?

1. DAC ...Cap.. battery bias CCS Cap
2. DAC ...Cap.. battery bias 10K/600ohm transfo
3. DAC... dc coupling, filament bias, CCS Cap
4. DAC... dc coupling, filament bias, 10K/600ohm transfo
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Old 1st March 2013, 05:50 PM   #2549
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Hi!

This will not work with a volume pot at the input of the pre. Depending on volume setting the DC offset would also be changed. And resistive pots tend to crackle when subjected to DC.

Best

Thionas
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Last edited by Vinylsavor; 1st March 2013 at 06:13 PM.
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Old 1st March 2013, 06:06 PM   #2550
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thanks thomas, so with DC coupling what about the grid leak resistor of the 26 ? put one or not? any value?
( the dac has 1V output level and 10K output impedance)
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Last edited by juanitox; 1st March 2013 at 06:11 PM.
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