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Best sounding transistors

Many people talk of tube rolling and the sonic differences they impart.  Output transistor are not easily rollable since they are soldered in place, but I'm curious about the sonic signatures different transistors might have.  Who makes the "best" ones?  Which amplifiers use them and what is the native/optimal output impedance on these devices?  I know there is a lot more to an amplifier than just the output transistors, but I'm just curious about this one aspect.  I'm not an electrical engineer either, so please keep it simple.  What do the Pass amps use?
thegoldengoose

Showing 4 responses by rodman99999

rodman99999
5,988 posts
 
 Nelson Pass has a supply of NEW OLD STOCK Toshibas(ie: 2SK170/2SJ74/2SK2013/2SJ313), that he's using in his newest amps.  NOS doesn't only mean, "new old stock" on ebay!
rodman99999
5,988 posts
 
"What do the Pass amps use? " Nelson is using NOS Toshiba JFETs(input stage) and NOS Toshiba MOSFETs(output stage) in his latest amps(the .8 series).
rodman99999
5,988 posts
 
@Goose-  Another type you might find of interest: Epitaxial Planar or Ring-Emitter transistors.  They've been used by Pass,  Burmeister,  Symphonic Line, Electrocompaniet, and other respected marques.   Seems the source now is Sanken.
rodman99999
5,988 posts
 
" This is what often happened in the old Phase Linear 400 amps back in the 70's and 80's. "  Their 700 had the same issue.   Those of us that repaired so many, often referred to the company as, "Phlame Linear". 
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