Joe Appierto
07-14-2012, 09:05 AM
For those of you who are obsessive with things audio, like me, I've come up with a spreadsheet to help in determining how to match up the small signal tubes in your c-j preamps.
I know that we often buy them as matched pairs to begin with but if you'd like to go one step farther these spreadsheets may be of some use.
They look at three characteristics: noise, Gm (which I believe is the same thing as transconductance), and gain. The idea is to arrange the tubes' into position so that the left and right channels match the most closely on the characteristic(s) you think is (are) most important.
Each of the spreadsheets (for 2, 3 or 5 tubes per channel) also has a sample of an actual matching I did for some Mullard PCC88s that I use in the Pr 16 just so you can see what it looks like.
Not every vendor supplies all of these measurements but it came in handy when I recently purchased some unmatched Gold Lion 6922s from Jim McShane.
I obviously have too much time on my hands. :D
I know that we often buy them as matched pairs to begin with but if you'd like to go one step farther these spreadsheets may be of some use.
They look at three characteristics: noise, Gm (which I believe is the same thing as transconductance), and gain. The idea is to arrange the tubes' into position so that the left and right channels match the most closely on the characteristic(s) you think is (are) most important.
Each of the spreadsheets (for 2, 3 or 5 tubes per channel) also has a sample of an actual matching I did for some Mullard PCC88s that I use in the Pr 16 just so you can see what it looks like.
Not every vendor supplies all of these measurements but it came in handy when I recently purchased some unmatched Gold Lion 6922s from Jim McShane.
I obviously have too much time on my hands. :D