Metropoulos Forum

My Metro50 has been performing great for 18 months. I just made a couple of changes:
1. Moved LarMar MV pot to front panel - used hole for bottom input jack of Ch1
2. Removed cascade mod and went back to jumped single input - tried this cascade several months but just doesn't sound that great.
3. Installed IEC AC socket to replace hard-wired pigtail.

Played through it for about 10 minutes after warming up, and twice the volume dropped to almost zero for a few seconds, then came back. I reflowed all the solder joints in the power section that I had changed. Played some more and it did it once more.

I hooked in a meter and all voltages were normal. Ran a steady signal from a keyboard for 30 minutes and of course it did not do it again. No visible change in any tubes.

Recently I had some of those very similar symptoms with my Metro 50. After I got thru with replacing a few resistors, and jostling the insides of the amp around, my amps loss of sound was because I originally made a very shoddy soldering joint where one of the heater wires connects to the v3 PI tube from the v4 power tube... Thus, none of the other preamp tubes were getting the proper juice.

Thanks for the tip Greg. That was why I reflowed the joints that I had changed, as it was just too much of a coincidence that it happened just after making changes.

Intermittent problems are a royal pain to track down. Have not been able to reproduce it again, which means next time it occurs will probably be on stage!