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Old 10th February 2010, 11:10 AM   #1
regal is offline regal  United States
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Default 6EM7 SET Headamp

Looking into adapting this to a headamp:Click the image to open in full size.


It has too much gain for a headamp so I would need to replace the battery bias with a resistor, I would also lower the output tube current and change the resistors to keep it DC coupled (haven't done those calculations yet.)

Anyway if I remove the battery cathode bias would this screw up the DC coupling capability of the amp? Possibly replace the first tube plate resistor with a CCS, which would give a stable plate voltage and stil 1/2 mu with an unbypassed cathode?

Last edited by regal; 10th February 2010 at 11:12 AM.
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Old 10th February 2010, 11:50 AM   #2
Gluca is offline Gluca  Italy
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Click the image to open in full size.

you may consider this schematic. it is something I am listening now and I am very pleased with. 6EW7 is quite similar to 6EM7. Gain is again high but I need it all as I am stepping up the signal out of my DAC.

I will move the choke from the upper triode V2 down to the lower V1 and use the CCS on the V2. Things should get better this way.

I R loaded the V1 as in kaufman schematic but the amp now sounds way better. AC filament elevated to 100V, no hum whatsoever.

gianluca
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Old 10th February 2010, 12:11 PM   #3
regal is offline regal  United States
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Quote:
Originally Posted by Gluca View Post
Click the image to open in full size.

you may consider this schematic. it is something I am listening now and I am very pleased with. 6EW7 is quite similar to 6EM7. Gain is again high but I need it all as I am stepping up the signal out of my DAC.

I will move the choke from the upper triode V2 down to the lower V1 and use the CCS on the V2. Things should get better this way.

I R loaded the V1 as in kaufman schematic but the amp now sounds way better. AC filament elevated to 100V, no hum whatsoever.

gianluca
Wow interesting tube DAC stage, makes me wish I hadn't given up on tubes for DAC's. You must be using a very nice low I/V resistor which is great for the DAC, no hiss?
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Old 10th February 2010, 12:20 PM   #4
Gluca is offline Gluca  Italy
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I am running the PCM1704 into 22ohm+22ohm (balanced DAC with multiple chips in parallel) and using a 600:50k mic in transformer.
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