Tube Amp Archive

Only, now the UK is no longer part of the EU, that'll mean import taxes apply to UK transformers as well. But you won't be paying UK VAT (assuming you buy from a VAT-registered supplier), so not much difference overall. I think I read somewhere that the Modulus transformers are made by Dagnall, but...

Yes, the first amp I built was exactly that. This was nearly 30 years ago, so I only have a photo of a photo...

No worries, I just wanted to see if you had them handy. It is hard to get real data on these amps. Most sources I've seen say B+ for the early AC30s was low at 310-320VDC, post rectifier (with 117VAC on the primary). I have three JMI AC30s, with Albion, Woden and Parmeko transformers. Might be a wh...

Most people building Marshall clones use a trim pot on the turret board. See step 14 here:

http://www.valvestorm.com/sites/default ... T_V2.1.pdf

What you wrote is not what I understood from reading the above links, yet the "risk" seems to come from the acids used to synthetise it. NB: 70% alcohol means 30% of other things. The 30% "other things" would generally be water, if you're talking about 70% isopropyl alcohol . It's quite reasonable ...

I found if I plugged into one channel and turned up the other channel. Nothing happens till I get to 12:00 on the pot, then there was an increase in volume, the brilliant channel sounded more like the normal channel. Plugging into the normal channel and turned up the brilliant channel, the volume d...

I had to use a chopstick and start moving wires, my heater wires didnt like how they were situated around the ohm selector. Thank you for the tip. I already "chopsticked" the whole amp with no results. But I will check the heaters again. I noticed that the shielded Belden COAX cable may be the culp...

Answer from Steve: factory closed until lockdown is lifted, but he's only ever done TB chassis anyway. Back to the drawing board.

No, I don't have his email address. The Valvepower website is down, so I sent a message through Ebay, but no response.

Bumping this because the links are dead and Steve S/Valvepower doesn't seem to be selling chassis any longer. So, does anyone know of an accurate AC30 (non TB) chassis that's currently available, or am I going to have to resort to CAD and draw it up?

That's my amp. :) ... How are those 4 jacks wired up on the diamond input models? It doesn’t seem to be documented anywhere :? Good question. IIRC, they're supposed to have high and low sensitivity inputs cf. the AC30 and Marshalls. Mine doesn't; all four have a 100k series resistor and they're con...

Bass and treble pots both measure about 710k. The 500k volume pot is 397k. Interesting... I'm used to seeing old pots drifting higher.

That’s amazingly helpful, thanks! Would you mind noting any (readily apparent) labels/markings on them also? Apparently the codes on this one can be cross referenced https://ibb.co/s9XfMCg Does yours have vertical can caps on the power amp chassis like this https://www.voxac50.org.uk/images/AC50s/4...

No,I haven't measured them. I'll have a look in the morning.

Looks like you've got it covered, but here are the photos.