The Amp Garage

Coax day before putting the transformers in.

martin manning wrote: ↑Fri May 09, 2025 5:06 pm Yes on the 100k replacing 220k. I have 75k and 27k with 10k pot, but your tubes may need something different to center the range. 82k in place 0f 75k would be close.

Thank you

When using Martin's bipolar supply, am I correct in understanding this involves changing the Ryan/Erwin layout with: 1. Changing the 220k cathode resistors to 100k 2. Using a 75k, 24k 10k-pot divider network for the bias range I don't have a 75k or 24k, but I think 68k, 22k and 10k-pot should give s...

Try plugging in to the effect return jack - it removes much of the circuit and can help to isolate the problem. Check wiring from there to the output.

The way the 470k resistors are wired, the amp will surely wake up your neighbours when you fire it up. The control grid should not be connected to the heater supply. Thanks Richard, appreciate the note of concern. PottedPlant is right, those are just dry fitted, not soldered yet. I paused to delibe...

Measures inductance, capacitance and resistance. Mine lives in automatic mode - clip the leads on and it will work out what component it’s testing. I got it originally as some very small capacitors have ambiguous labelling so it was impossible to be sure what you had. Do you test individual compone...

Measures inductance, capacitance and resistance.
Mine lives in automatic mode - clip the leads on and it will work out what component it’s testing.

I got it originally as some very small capacitors have ambiguous labelling so it was impossible to be sure what you had.

Stick a jack in and you’ll see the tip connect and the switch opens. Jack = female, Plug = male. Except for donkeys and kangaroos ;^) :D ... or us Europeans . I had never known it was an abbreviation we'd applied to "jack plug" - around my parts they're generally jacks and sockets. Thanks! I can’t ...

Those are 12A and correct. Stick a jack in and you’ll see the tip connect and the switch opens.

12B has the extra mechanical connection that connects the ring section of a stereo jack.

You’ll find that from time to time, the wrong part will be put in by whoever is packing your order… The 12b is for a stereo jack, with 3 connections for left, right and ground. That’s what you have with the black jumper wire. The 12a is for a mono jack, also with 3 connections. It has a ground, and ...

Thanks. It's a bit grainy, but it looks like the speaker jack is plugged into a stereo socket - that's OK in itself, but please verify the wiring. On all the sockets I've used, solder lugs are on the opposite side to the mechanical connection, like this: Screenshot 2025-04-30 at 11.35.54.png Please ...

I’m really not trying to nag, but did you address the stereo jack sockets on the speaker and effects loop? I ask because you will start to damage the output transformer if you power it up with a short circuit, which I *believe* the first photo shows (I could be wrong).

Deleted (had a typo with the wrong part number, corrected by Martin in next post)

Looking good, however the 500ohm/5w resistors are very close to the Grid1 terminals on your power tubes. Those two points combine to make the highest voltage potential in the amp; Bias- to B+. That's putting a LOT of faith in the resistor coating to insulate against. If it were mine I would careful...

Watching the incredible captaincoconut #5 build thread motivates me to get back to this. I'm using teflon for the first time, as I've always admired the Amp Nation builds. 22AWG/600V for the preamp and grid signals and 20AWG/600V for B+ line and screen, then cloth 18AWG for the heaters - please say ...