The Amp Garage

I generally get what works out to be $10/hr (local Aus currency) for the building and mods I've done.

Less would make me feel ripped off and like I'd rather spend the time on my own building backlog. More starts adding up to the point where the project doesn't go ahead.

Just out of interest because I've already got it, here's the sweep response of the full Bass channel from LTSpice modelling. If you put the bass tonestack into Duncan TS Calc you'll see it's almost a ramp increase toward the treble end. Even after the treble control stage it's actually very treble h...

Hello Katopan, I recall there being some issue over the schematic of the Bass channel and specifically over how the tone stack was wired. Some owners said their bass channel was thin for guitar, others say it was usable. I believe this had to do with how the bass control was wired (or not wired). M...

Good to hear you're progressing with the build. I've got to do a simple demo clip one day of the Bass channel. Everyone passes it by but it is great for guitar. It has more gain on tap (still mild) with the treble turned up a bit than the Normal channel. The clean is different but sounds fantastical...

Hi Brewdude!

Stupid amount of effort really. But I got a true 30% taper, right tap resistance and right overall resistance so I assume it's very close. By the time I was making the pot I had given my friend's original 6G6-B back to him so couldn't compare.

martin manning wrote: ↑Thu Dec 12, 2019 2:05 am Yes, the circuit you modeled is correct. True, the response is somewhat different, but maybe not in a bad way. For sure, adding a couple of resistors is a lot simpler than adding a tap!

Can't argue with that! You've done well to capture a similar response.

Hi Martin. I thought I had seen your alternative circuit, but thanks for attaching it because I actually hadn't. I added it to the LTSpice simulation file I used for the Blackface vs 6G6-B treble sweeps I posted. Here is the result. Please check the schematic and make sure I've read your layout modi...

I had a real '64 transistion era (Blonde circuit, cream knobs but black tolex) in my hands a few years back and it inspired me to build my own. Fantastic amps! You should reconsider installing a real tapped pot. It's part of the 6G6-B magic that the alternative circuit is lacking. I really like how ...

Littlewyan wrote: ↑Wed Sep 11, 2019 8:14 am When you measured that were you running EL34s or 6V6s?

Good question! Sorry didn't think to clarify - definitely EL34s. I don't think much of an Express with 6V6s in comparison to EL34s.

My amp is the Express circuit true to the schematic but with a very different layout.

Fully cranked I've measured 74V across the 1K resistance which equates to 5.5W. But it's mounted inside a chassis and with the 2:1 safety factor that's been mentioned a 10W is marginal. Also if you look at the temperature rise info for those resistors, a 10W will get really hot hanging in free space...

After some research for a recent speaker cab build, I was reading about how wiping varnish was just standard oil based poly varnish "watered down" with mineral spirits. After a bit of experimentation I ended up with a 50/50 mix just in a glass jar. I'll never go back to anything else! I painted it o...

Man, I could listen to that all day long. Great amp!

My reply is going to be unconventional, so take it for whatever you want. In my Express build with EL34s and standard voltages I used two standard 5W wire wound resistors to make up the 1K at 10W. They are mounted with a bit of aluminium channel I bent up holding them against the aluminium chassis. ...

I have secondary taps in my Express build and just switch them with standard mini toggle switches. Never live switched though, always with the power off. That way they never break running current. It's exceeding their voltage rating, but that is more once again about switching and extinguishing the ...

Katopan: whatever you do, focus on the most important task you need to get done and build your rig for that. Don't attempt to make it a one size fits all solution. Keep it as simple as you can and with that you will get a good result. When you make it complicated, it's much harder to make it work r...