jelabs 76/6sn7 linestage
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jelabs 76/6sn7 linestage
by janna » Sat Nov 24, 2012 10:34 am
Plan to build this preamp and i just want to check if it works well with my 6v6 based amp. anyone have idea what is the gain of this linestage?
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by Shannon Parks » Sat Nov 24, 2012 5:26 pm
It looks to be around 22dB or 12.4 times gain. So a 100mV input at your preamp would be 1.24V with the volume pot wide open. Seems like plenty of gain.
Shannon
Shannon
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by Geek » Sat Nov 24, 2012 11:07 pm
separks wrote:It looks to be around 22dB or 12.4 times gain.
Yikes!
-= Gregg =-
Fine wine comes in glass bottles, not plastic sacks. Therefore the finer electrons are also found in glass bottles.
Fine wine comes in glass bottles, not plastic sacks. Therefore the finer electrons are also found in glass bottles.
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by Shannon Parks » Sun Nov 25, 2012 6:17 am
I went ahead and modeled the 76 to double-check my SWAG. Below is the schematic, and also Gary Kaufman's similar line stage.
Stock JE Labs gain is 9.2X or 19.3dB gain. -3dB at 26kHz with 250K volume pot set at 50%.
I would probably change to a 100K pot, which would mean -3dB at 66kHz with the pot set at 50%. You can also remove the cathode bypass cap and change the gain to 5.2X or 14.4dB gain. -3dB with 250K pot at 46kHz. -3dB with 100K pot at 115kHz. Upping the output cap to 0.47uF is probably a good idea, too.
Shannon
Stock JE Labs gain is 9.2X or 19.3dB gain. -3dB at 26kHz with 250K volume pot set at 50%.
I would probably change to a 100K pot, which would mean -3dB at 66kHz with the pot set at 50%. You can also remove the cathode bypass cap and change the gain to 5.2X or 14.4dB gain. -3dB with 250K pot at 46kHz. -3dB with 100K pot at 115kHz. Upping the output cap to 0.47uF is probably a good idea, too.
Shannon
- designer of fine tube audio gear at (((parks audio)))
- founder and admin of the diytube forums
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Shannon Parks - Site Admin
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by TomMcNally » Sun Nov 25, 2012 2:45 pm
Those 76's are known to be highly microphonic. It might be
a good idea to shock mount them on rubber somehow.
See one I built at http://tmamps.com
a good idea to shock mount them on rubber somehow.
See one I built at http://tmamps.com
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Re: What is the sound?
by Thunder » Sat Dec 01, 2012 10:17 pm
janna wrote:Plan to build this preamp and i just want to check if it works well with my 6v6 based amp. anyone have idea what is the gain of this linestage?
Hi janna!
What is the sound this Line-Stage?
Thank you!
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Re: jelabs 76/6sn7 linestage
by SDS-PAGE » Thu Dec 13, 2012 4:18 pm
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