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    Building, troubleshooting and testing of these amplifiers should only be
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    the safety precautions around high voltages.

Pre amp tap

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nzlowie

Member
Joined 2015
Hi all, I've got a Sun 2A3 amp to drive my mid/hf horns and run a DSP amp for the bass section. My question is can I take a tap off the 6SN7GT driver tubes to feed the DSP amp? The Sun has plenty of gain so I don't really need another pre amp. The DSP amp has an input impedance of 10k .

Appreciate your thoughts.

Cheers Dave
 

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rayma

rayma

Moderator
Joined 2011
Could work, though doing that will add distortion and pull down the gain quite a bit from loading that node with a 10k. You'll cut off the bass response also, to around 70Hz (instead of around 3Hz now). You'd have to enlarge the coupling capacitor to at least 1uF to mitigate that. Also I'd add a series 1k resistor in the wire to the DSP amp.
 
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nzlowie

Member
Joined 2015
Thanks guys
The reason for this idea was around the loading of the DAC. I found a big improvement when I placed the B1 buffer between my DAC and the 2 amps. The DAC likes a higher impedance than the 2 amps in parallel gives. 100k for the tube amp and 10k for the DSP amp.
I still want some gain as the mids are a lot more sensitive than the bass section. Bass amp does have a lot more power.
Tap after the first section of 6SN7......
 
PRR

PRR

Member
Joined 2003
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> The DAC likes a higher impedance than the 2 amps in parallel gives. 100k for the tube amp and 10k for the DSP amp.

What is this "DAC"?

100K||10K is 9K. "Most" DACs are under 100 Ohm output impedance and will drive anything over 1K with no strain. So is this DAC "special"?
 
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nzlowie

Member
Joined 2015
The DAC is an Australian product that sounds very good and used in a lot of top systems over here. According to the designer due to the line transformers on the output it like to see a higher impedance. And yes it does sound better when feeding a buffer than when direct into the amp.
 
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