The Amp Garage

What's up with the duplicate 320K resistors?

Hi Aaron, with a guitar plugged in and the volume knob all the way down, do you get any guitar sound coming through? Most or all of us have run into this with our builds.

Also, what is the measurement on the PI pot?

Thanks

With V1 and V2 (both 12AV7) only, B+ readings were steady at 278-266-249-239-261 V. The last node is higher because it is paralleled off Node B. V1 (wired in parallel) plates 129 V cathode 4.3 v grid .1 mV V2 gain stage with cathode follower pin 1 83 V Pin 2 .4 mV Pin 3 2.35 V Pin 6 238 v Pin 7 .4 m...

Damn......

@pullshocks there is no any picture of build or voltage measured, how we can help? obviusly something is wrongly connected, amp is burning the tubes out..6F4P are russian if i understand well, so this means voltage cannot be high. so lets start from 0, remove output tubes which i assume are burned ...

As far as the PI output coupling caps, other than pulling them out and checking capacitance and resistance with my DMM, is there any other test I can do? Check for DC leakage. Leave the caps in circuit. Clip your meter probes to each side of the cap. Check for DC voltage. Caps should not pass DC, o...

While I built this one, I never kinda bonded with the original design and sound of these 'combo' tubes. Added another double triode and 'proper' power pentodes (cheap, abundant and great sounding 6P1P Russian tubes) and it turned out a great little amp (plus some 'options' that I added along the wa...

The microphonics is telling you that there is a structural problem with the output tubes, and that is the source of the arcing and inturn the popping that your hearing. I would also check your PI output coupling caps for signs of DC voltage leakage. Thanks Stevem. New tubes on order. As far as the ...

I recently finished a build from the SoLow Watt design that has been built by several on the Hoffman and AmpGarage forums. It is a push pull amp. I used 6F4P tubes instead of ECL84. Schematic attached. All new parts, except the tone caps and PI coupling caps. I got the 6F4P from a member on the Watt...

Maybe I'm overthinking this, but I wonder why they chose that spot on the chassis to do the ground reference, as opposed to the pilot light or other spot in the power supply area. Simplest explanation would be there is plenty of room there in mid chassis, and leaves room to add the DC heater compone...

Looks like the amp in the picture is being wired with AC heaters. Heater wiring is twisted all to all tubes. The heater CT appears taped off. Heaters appear referenced to ground via 2 100 ohm resistors on a short terminal strip mid chassis.

CraigGa wrote: ↑Sun May 23, 2021 7:16 pm Just to prove that I'm good at something I put the pictures through my Bladerunner device

I have to confess my ignorance, what is a Bladerunner device?

Thanks, nice to be able to blow the image up...

In the pic of the original Monarch gut shot on page 6. The Reverb and preamp share the same node(white wire). I wonder if that Monarch has volume bleed? In that picture, it looks to me like all 3 12ax7s get their B+ from the white wire that comes out under the tone pot, i.e. from the same node. Whi...

The EB tank arrived today, sooner than expected. (Yay StewMac!) I swapped back and forth between the 2 tanks a couple times, and at a few different reverb settings. My conclusion: both FB and EB tanks work fine in the circuit. I would say there is a bit more verb with the EB, and maybe a little brig...

Thanks for posting. Enjoyed the Soundcloud. Thanks :) Interesting that you are using an xFBxxx tank, as I am. I ordered the "correct" xEBxxx, it should be here in a few days. I don't really see how xEB is "correct"? Swart amplifiers use very similar (if not the same) reverb arrangement with xFB, Tr...