The Amp Garage

If you have not ordered any parts yet then you might like this set up with a bias trimmer and a balance, and it also acts like a fail safe in that if the wiper on the trimmer ever goes open then the full bias gets applied too keep the tubes well below a burning up state. Steve, note in the diagram ...

Big bummer... Red plate city!! Not reading any proper negative voltage at the grid bias resistors, except for hundredths of a volt. Quadrupled checked the new wiring with the new parts. Maybe I cooked the trimmer... Is that possible? It still reads resistance at about 56K, and at its halfway point ...

hebaton wrote: ↑Mon Jun 02, 2025 8:42 pmThis unit feels very stiff, I wonder why that would be and what, if anything, I can do to change that ?

What's the value of the first ("reservoir") fitler cap?

hebaton wrote: ↑Mon Jun 02, 2025 6:18 pm About the quality of the work, here are a couple pics.

Some solder points look OK, but many are ugly, and might be poor electrical connections. I'd go through and retouch.

Yes, bias voltage was -34 or very close. I'll remember to scope the output if I still have oscillation after replacing the filter caps.

Owner decided it's to be a player. Needs new power cord, lift death cap, check resistor drift, etc. Next week. Thanks, peeps.

On the bench is a near-mint '66 PR. It plays and sounds OK, but anemic (only 2w output, with a little assymetric ringing). Voltages are all close to spec. Tubes are all original, so may be weak, or original filter caps are weak (however, no hum, very low 2v AC ripple at B+1, no ripple on bias voltag...

I've been playing this amp at home with a variety of overdrive, distortion, and fuzz pedals. Sounds great. But even with pedals engaged, I'm not pushing a signal that's any larger than usual into the amp. Nowhere close to overdriving the LND150. 12A?7s are linear when they're not being driven into d...

I noticed the same deal when positioning a choke between PT and OT. Bends the field.

Very nice clean build, as usual with your builds! Yeah, not every great sounding build is also bedroom friendly. How's the baseline hum? I've never worked on a Liverpool, does the original have the O.T. and power xfmr on top of each other? It looks like Ken had real estate to spare. Just curious. I...

Looks absolutely beautiful ! I love having an LND 150 input stage in front of my amps! Your method is a very cool way to build it. ( I usually buy it already assembled on a Cliff jack ) Is there way you can roll off the gain on your LND 150 with a Trimmer pot? Thanks for posting! Cheers Guy No, I d...

Built a cherry hardwood cabinet with walnut valence, gloss polyurethane, and got the faceplate installed. Glamor puss shots.

Update, update. I posed a question to Josh @ JHS asking to clarify the various marketing material indicating that the NOTADUMBLE is suggesting it's a exact replica (his words) of the Dumble A Box Later. I carefully presented the case that some things aren't lining up based on the gut shots Gil prov...

TUBEDUDE wrote: ↑Wed May 21, 2025 7:34 pm It might be a public service to identify the manufacturer that fuses the bias voltage.

That looks like the heater circuit to me...

Likely the PI is working as it should but signal is not arriving at input grid. Confirm working PI voltages. Confirm continuity from grid to 1M/0.1u. Have a scope? Trace the signal.

FUCHSAUDIO wrote: ↑Thu May 15, 2025 7:05 pm I do have a real problem with any amp covered in useless silicone snot.

Well, not entirely useless. This is a combo amp, and all the chassis-adjacent wire runs are tacked down to avoid rattles. But, yeah, there's a lot of unnecessary goo, too.