Extremely microphonic V1

[Stuff4bikes]

Build is a couple months old, no noise that I recall when built....pulled it out yesterday and it sounded terrible, tapped on the 12ax7 and ping ping ping tapped on the chassis and same thing....
Swapped in a known good AU7 and same thing and rocking the tube created a squeal.

Stout TMB---- 12ax7's El 84's and EZ81 all RCA's -------NOS Belton sockets

[sluckey]

Is that Hoffman's layout? I would not rock that tube with the power on.

[Stuff4bikes]

Yes, Hoffman's layout.....
Only rocked it once, actually straightened it back up.....

I found the cathode wire when tapped would ring out so I reflowed all the connections.....helped but V1 still noisy with a chopstick on the glass.....no noise when pecking on the other wires underneath...

[joesatch]

i killed a new mullard on a recent build because i was soldering the socket connections with the tube in it. I keep forgetting to pull tubes when i make changes

[pdf64]

That’s strange, I can’t see how soldering would damage a valve? Please tell more.   

[Bieworm]

I learned the hard way that there HAS to be a tube in the socket while soldering. It happened to me one time solder flowed inside the pin clamp, which made putting in a tube impossible.  So that's the only time I use JJ tubes ... when soldering on the tube sockets.  That's all they're good for nowadays😁

The microphonic problem... check if all ground soldering is solid. I had the same problem on my 6G3 build. Microphonics when tapping the chassis.  Turned out to be a bad connection to the ground buss

[Stuff4bikes]

I don't solder with tubes in. I put the power cord on last because I flip the chassis on its sides so I can solder with the pins as flat as possible.
I hate fighting that power cord...

[mresistor]

Use an old dead tube(s) for the soldering process.

[HotBluePlates]

... tapped on the 12ax7 and ping ping ping ...

FYI, that is not "extremely" microphonic.

I received some tubes once that actually were extremely microphonic. With no cable plugged into the amp, turning any Volume control above ~25% resulted in the amp emitted a full-power howl/groan.  It was like pointing a microphone at a speaker, except at a lower frequency.

Those 5 tubes went in the garbage, and I never bought that type again.

[Stuff4bikes]

... tapped on the 12ax7 and ping ping ping ...

FYI, that is not "extremely" microphonic.

I received some tubes once that actually were extremely microphonic. With no cable plugged into the amp, turning any Volume control above ~25% resulted in the amp emitted a full-power howl/groan.  It was like pointing a microphone at a speaker, except at a lower frequency.

Those 5 tubes went in the garbage, and I never bought that type again.

I had that also. Mostly with 12ax7's...with power tubes I get that ocean waves noise out of the speaker

[TigerTrading2021]

This thread reminded me I own a secret weapon. I bought thousands of dollars worth of tactical flashlights to resell (dumb dumb dumb) the flashlights are terrific but Im not a sales person so I have a ton of them. All CREE XML V2. Anywho the very first one I got as a sample has a fault in the driver circuit that lo and behold emits something not sure what. But when you get it near a faulty microphonic preamp tube it will make the tube give off a noticeable sound. Wish I knew how to replicate this effect as it seems to be very useful. I have no way of measuring whatever emi rf thingy it is putting off.

[southboundsuarez]

That certainly is an interesting tendency and gives creadance to the many folks that complain about cheap Chinese junk. ( I believe that we have cheap offshore goods because that's what we demand)  Anyways, some sort of very high frequency oscillation. Have you tried putting the flashlight near a radio antenna and sweep the dial? perhaps a scanner type radio with Vhf and Uhf frequencies?  Even better a wide band communications reciever or ham radio?
How much for a flashlight anyways?

[TigerTrading2021]

I have lots of these flashlights I have 2 different chargers a 2 battery and 4 battery. And 2 Flashlights both have the CREE XML and work the same Lo Mid High SOS & Strobe and they have mode memory. The smaller flashlights have an orange peel reflector and are great for looking around in dark rooms or looking at equipment etc. The larger one has a smooth reflector and longer range and will light up trees a block or 2 away easily.
smaller flashlight with 2 battery charger and 2 18650 batteries 25$
larger light with 2 battery charger and 2 18650 batteries 32$
the 4 battery charger will charge a lot of different batteries including NiMh and Lithium 14$ and 8$ for a cigarette lighter adapter for the 4 batt charger.
As far as all the radio suggestions I have no access to any of those but it is a good idea and I do want to know why this one does what it does.