The Amp Garage

usually tube is microphonic in stage where is maximum gain..and input signal very low... V1 position.. tube rolling can help.. also adding grid stopper too.. microphonic tube shift to PI position, and some short plate 12AX7 to V1..

Metroamp also added few metal oxide resistors 3W in their version, maybe for a reason

bepone wrote: ↑Fri May 31, 2024 7:19 am it is possible to change few components without major change in the sound, because all together it counts..there are many compoents in the group at the end.. so if something is missing regular carbon film will be ok (modern cheap SR Passives or TE )

ofcourse 1-2W not less

for Marshall metal film and polypropilenes should be avoided because result is awful .. been there... recipe is carbon film + polyester

it is possible to change few components without major change in the sound, because all together it counts..there are many compoents in the group at the end.. so if something is missing regular carbon film will be ok (modern cheap SR Passives or TE )

1. internal tube structure problem, some bad assembly, then arcing internally..

2. on sockets because of flux between in 2 and 3, which with time strting to be conductive.

3. because of bad sockets, porosity in materials and humidity

Me too. But prices are too high... so i changed, i have luck nowadays with axial TAD Mustard caps (probably also chinese, cheap, but sounding very nice), looks good too

edit, this post on top is for working amp here is major problem short circuit to the ground on Ub+ line, so new procedure: 1. switch off the amp 2. drain all the capacitors , with 10k to the ground until discharges 3. multimeter in ohms, and touch every node on + cap and to the ground, find out whic...

1. remove feedback wire from the speaker terminal

2. start amp again

3. if there is no any noise and amp works, switch off

4. change anode wires from OT to pins 3 - sockets, A1 <-> A2

5. start amp again, verify all is correct

font , colors, quite bad printing and shape looks like Sozo

1mV AC balance on cathodes? this is negligible... also 2mV is negligible (impossible to hear that), i would leave this like it is

Maybe the 12-65 Creamback, but the AlNiCo Creamback is anything but dark. Alnico Cream.. i have 2 pcs.. also is not bright too.. playing this speaker last 2 years...now is too smooth.. sound is great. Saying that will be good to try Neo Creamback and Alnico Cream in 212 box, probably they will make...

Sockets are how i see new.. and Belton, so means high quality.. Never failed any in my life. So there is only 0.1% of chance that sockets are a problem.. Probably output tubes..

This is bad tube problem.. pls measure resistance directly on the tube pins, between 2-3.

Its a shame you can't get 220uF in non polarized form in a non gigantic form factor as that would be the easiest way to deal with this problem lol. I Now i see you are too young and green.. it is ashame that you dont know this :mrgreen: : 220uF is very easy to make, from 470uF + 470uF regular elect...