Metropoulos Forum

Hi All -
I'm new here. Built a few things (5F6A and 5E3 and aborted KLD 5F6A). Just finished the ValveStorm JTM45.
Voltages seem OK with my Fluke87. But when I plug in the KT66's and put a speaker load on and turn on the Standby
switch, I get this super loud hum/buzz. When the KT66's are not installed, the filter caps charge. But when the KT66's are installed - the filter caps DO NOT charge. Hmmmm. Any ideas guys? I could take this to my Tech here in Northern NJ, but
I really want to fix this myself. I've been putting my best foot forward, learning all I can. Can you guys point me in the
right direction? Thanks in advance.

Jeff OD

A loud buzz or hum is usually the sign of a faulty ground connection. I would go over the connections on the output tube sockets and make absolutely sure they are correct (easy to get the order slightly wrong so you end up with something grounded that shouldn’t be and so on). Also check all other connections that are supposed to be grounded, particularly the output (speaker) jacks.

Thanks Shakti -
I appreciate you getting back to me. After sorting through the forum, I discovered that when the output wires from the OT are reversed on the Power Tubes that the hum is overwhelming. The fix (test) was to remove the negative feedback wire from the speaker impedance selector. This I did and the amp sounded great! Soooo - - all I have to do now is to reverse the OT wires to the power tubes and reconnect the negative feedback loop and were OK. Not sure if this was specified on the instructions. Thanks again. Jeff OD


A loud buzz or hum is usually the sign of a faulty ground connection. I would go over the connections on the output tube sockets and make absolutely sure they are correct (easy to get the order slightly wrong so you end up with something grounded that shouldn’t be and so on). Also check all other connections that are supposed to be grounded, particularly the output (speaker) jacks.