July 15, 2012

  • Small Signal Tube Matching Spreadsheets

    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 preamps.  The spreadsheet was originally intended for conrad-johnson preamps that use multiple 6922s in each channel but will work just as well for any preamp that uses 2, 3, or 5 identical type tubes per channel. 

    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. 

    The spreadsheet looks at three characteristics: noise, Gm (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 spreadsheet also has a sample of an actual matching I did for some Mullard PCC88s that I use in the conrad-johnson Premier 16LS2 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 (review forthcoming).

    I obviously have too much time on my hands. 

    For 2 tubes per channel:  File Type: zipZip Pr 17 Small Signal Tube Matching.zip 

    For 3 tubes per channel:  File Type: zipZip Pr 16 Small Signal Tube Matching.zip 

    For 5 tubes per channel:  File Type: zipZip ART Small Signal Tube Matching.zip 

    As always, comments are welcome.