dumb G9 question - matching

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kruz

Well-known member
Joined
Jun 4, 2004
Messages
301
Location
Cremona, ITALY
Hi all..
i'm strating to populate my G9 boards and i was wondering about stereo matching..
What parts should be worth matching to get equal performances on both channels?
How about the tubes? Is it really worth getting matched pairs?

too many dumb quetions :wink:
 
Thank you Jakob..
Could you please also explain me why? I'd like to understand while building your great project.
How about other parts? anything worth been matched? (beside the gain switch resistors)
 
If you use standard 1% resistors, you don't have to worry. I would use tubes that aren't too far apart, but not nescessarily matched. The circuit uses feedback, so the exact tube specs aren't that important.

Best regards,

Mikkel C. Simonsen
 
oh.. feedback..
now i see that.. :oops:
thank you Mikkel :thumb:
Now, thinking about stereo matching i think that the worst part that could compromise the matching could be the 47k log pot for the output.
Well.. i was thinking to swap it with a simple 1x12 Lorlin (stopped at 11 position to get 300° indexing as the input swicth)
I'm trying to use this calculator for the R values for each step:
http://www.quadesl.com/attenuator.html
But it's unclear to me what should i enter in the "total attenuation" field.. :roll:
any idea?
 
Hi Kruz,

I would recommend that you first build the unit as it is, and then later decide if you need to modify it for stereo operation. My guess is that it won't be an issue even with standard components.

Jakob E.
 
that's fine jakob.. but i'd like anyway to be able to easily recall settings.. i really like to have steps ..
 
The real issue here, if there is one, is the overall gain of each channel. If you have the gear to do it put a tone say 1khz thru each channel and measure the output . Find the setting on the level control which gives the same from each channel. If the valves are about the same the feedback will equal out the gain. Personally I would not change the pot for a switch as then you will then not then have the fine adjustment you might need to balance two channels into stereo.
Steve
 
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