Hello
I have a Melos 333 phono stage which use 2 X 12AX7 and 2 X 6922/6DJ8.
I'm not sure where the 12AX7 and the 6922 go. As is, the 12AX7 are at the output stage and the 6922 in the front stage.
Like it is now, this phono stage doesn't have too much gain with big bass and no treble. I suspect the 12AX7 could go in the front end and the 6922 at output. I don't want to try that because I'm afraid to break something
Thanks
I have a Melos 333 phono stage which use 2 X 12AX7 and 2 X 6922/6DJ8.
I'm not sure where the 12AX7 and the 6922 go. As is, the 12AX7 are at the output stage and the 6922 in the front stage.
Like it is now, this phono stage doesn't have too much gain with big bass and no treble. I suspect the 12AX7 could go in the front end and the 6922 at output. I don't want to try that because I'm afraid to break something
Thanks
If you put the 6922 in the 12AX7 socket, it won't light up because the heaters are different wiring, like wise for the 12AX7 in the 6922 socket.
It would make sense to use the 6922 in the input position due to the lower input capacitance. It is possible that they are using the 6922 as cascode in that position. It is possible that you have a weak tube or some other circuit problem. You could try replacing the tubes with known good ones and see if it improves.
If you post some pictures of the guts the folks here can probably figure out for sure where things go and what topology you have as well as possibly notice something amiss. Worth a shot. Just be careful opening it up as there are high voltages involved and of course it is best to remove the tubes before flipping the bad boy over.
If you post some pictures of the guts the folks here can probably figure out for sure where things go and what topology you have as well as possibly notice something amiss. Worth a shot. Just be careful opening it up as there are high voltages involved and of course it is best to remove the tubes before flipping the bad boy over.
Finally, the tubes were correctly placed. Tubes were tested and have 100% transconductance. The sound is muffled on both chanels. RIAA is passive between the two stages on a separate board. First stage have good square waves at 20 khz but second stage seems to be limited on the highs when I feed it without passive RIAA. I really don't know if it is normal to get correct RIAA curve. The second stage 12AX7 seems to drive IRF610 so the mosfet input capacitance is perhaps a tough load for the 12AX7.