shamu144
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I found some technical information on a diy forum which might be of interest to those who own the T2 or similar amps..
Quote:
Originally Posted by rich1051414
Lots of tube preamps(low voltage with buffer) are coming out lately, but I don't like the chinese tubes in them, those tubes aren't really good for the job, so the amps end up being underwhelming.
Anyone went down the rabbit hole yet and want to share what they have figured out?
If you open one up and trace out the circuit, you likely will find a 24V B+ (+-12V really) triode connected cathode follower circuit driving an Op Amp. The short pole is the under voltage 6J9P circuit, not the brand name of the 6J9P. If you have to change something, change the Op-Amp. It is doing most of the heavy lifting. After that, you can get a bagful of low cost 6J9P and find a pair that you like the most. Low voltage B+ tube rolling does work to a certain degree. Tube to tube variation can be large at those low B+ voltages.
Quote:
Originally Posted by rich1051414
Lots of tube preamps(low voltage with buffer) are coming out lately, but I don't like the chinese tubes in them, those tubes aren't really good for the job, so the amps end up being underwhelming.
Anyone went down the rabbit hole yet and want to share what they have figured out?
If you open one up and trace out the circuit, you likely will find a 24V B+ (+-12V really) triode connected cathode follower circuit driving an Op Amp. The short pole is the under voltage 6J9P circuit, not the brand name of the 6J9P. If you have to change something, change the Op-Amp. It is doing most of the heavy lifting. After that, you can get a bagful of low cost 6J9P and find a pair that you like the most. Low voltage B+ tube rolling does work to a certain degree. Tube to tube variation can be large at those low B+ voltages.
