Zesto Andros PS-1 Tubes

I lived with the stock tubes for quite a while and was very happy. I only swapped them out when I was chasing some noise gremlins (which turned out to be a preamp tube).

I started with a set of Tungsram-Austria labeled 12AX7's and a set of Telefunken ribbed-plates. Not bad, but seemed to be lacking something....maybe too much of a good thing. I swapped a in set of Mullard M8137's in the front positions since I was familiar with them and put the Teles in the back. This was a good pairing and one that I could live with - balanced without overemphasizing any particular frequency band.

I recently swapped out the front pair of Mullards with some GE 5751 TMBP that were a favorite in the buffer spots of my Minimax. Still plenty of MC gain using a DL103R. Probably a bit more focus.

I'd like to know the tube layout/function for each position. I'm assuming the front spots are the input tubes and the rears are the buffers. One reviewer mentioned swapping only one of the stock JJ's with a Mullard, so........

A co-worker replaced his stock tubes with Psvane Treasure high grade tubes - he is very pleased with htem.

A co-worker replaced his stock tubes with Psvane Treasure high grade tubes (Grant Fidelity)- he is very pleased with them.

@Roblanger

Reviving an old thread. Did you ever find out the tube layout for the Andros? I'm using NOS 1960's Brimar's with good performance, but the bass is a little loose and I wanted to try something else. It would be cool if I could try to swap out one pair, but which pair should I start with?

Answering my own question:

Front Left = V1 = Left Output
Rear Left = V2 = Left Input
Rear Right = V3 = Right Input
Front Right = V4 = Right Output

I started tube rolling last night. I have been listening to a set of NOS Brimar's for about a year. They sound great, just a little on the warm side of neutral.

I picked up a pair of 1966 Amperex Holland (labeled Electrohrome) and installed in V1/V4. Brimar's are still in V2/V3. The Amperex appear to have about 2db more gain. The soundstage really opened up, it's much more 3D than the quad of Brimar's. Vocals (both male and female) sounded breathy and fantastic. Everything sounds more lively and I really like this combination.

I have a pair of military Mullard's and a quad of Telefunken's being delivered soon, so I'll try a few more configurations and post my results.