Tube Amp Archive

Ted Weber used to sell an amp switcher that would switch multiple amps on the outputs safely to a load or a speaker. It was called the Four head and it could switch 4 at a time. I have the last one made before they discontinued it. They still make a switcher but I think it only does two amps at a ti...

I had a Super Champ back in the day, in fact it was my first amp. It was thick sounding when the boost was on, and was a unique sound, but it was also brittle sounding and boxy sounding, probably due to the use of the solid state rectifier and high voltages, and the small cabinet. I ended up selling...

Greg, in addition to the people you've mentioned, I miss Steve Ahola. It's sad that his site, blueguitar.org, became lost when he was gone and unable to renew the domain name registration, and somebody snatched it. Tboy was able to host an archived version of blue guitar at MEF, but now they're bot...

I really hope it gets back up and running again, it was a fine forum. Fingers crossed for it's return. You know I had no idea that Enzo had passed, man that's sad. I'm so behind with events. Cheers all. Yeah a lot of the folks on the forums are getting old. Enzo passed early last year I believe. PR...

xtian wrote: ↑Wed Jun 18, 2025 10:45 pm

Littlewyan wrote: ↑Wed Jun 18, 2025 10:42 pm Are both 6L6s drawing current?

And what are the voltages? Cathode or fixed bias?

Vintage Supro 6420 Thunderbolts are cathode biased with a 200 ohm resistor to ground off the power tubes.

Greg

The following voltages are loaded. B+ first node 380 2nd node 374 3rd node. 324 4th node 258 Cathode voltage on outputs at idle 28.48 V1 plate 255 V1 cathode 2.42 V2A plate 193.8 V2A cathode 1.98 V2B plate 153 V2B cathode 1.38 The output wave form looks good. I did a quick check of the OT by pumpin...

MEF seems to be having an existential crisis. tboy apparently hosts the whole thing on his own hardware, so he has to keep both going. Rumors say he has health and other problems. I hope it's backed up. Tboy was hosting the MEF forums on his own server in his garage for decades. Worked fine except ...

I'm actually OK with electrolytics. The Kemet PEG124 series are rated for 27,500 hours at 105c. That's kinda-plenty. https://content.kemet.com/datasheets/KEM_A4011_PEG124.pdf They're not too huge, and plenty good for bulk capacitance and they're not unreasonably priced for axial caps these days. If...

Are the Solen Film caps smaller than the motor run film caps? I was going to use some in a Sunn 2000S that I have because the chassis is huge and has the room. I'd hesitate on trying to fit them in a Fender BF/SF chassis though. No way they would fit into a Tweed Fender chassis. Obviously they can b...

Hopefully nosaj can get it figured out soon in between everything else he has going on.

Greg

Yeah and this time it seems like it is more down than previous times. Can't even get it to load. Wonder if maybe some payment wasn't made or the DNS is messed up or something. When I tried to load the Sunn page it came back after a moment and basically showed that everything is working except the si...

greg, my hat is off to you for all of the work that you put into that amp. I can't imagine how many hours of work it took to design and then perform all of those upgrades while working in such a tight space with parts that were wrapped and coiled, then soldered. de-soldering must have been a nightm...

Here's an interesting way to upgrade the reverb on a Silvertone 1484/1485 if anyone is interested.

https://www.youtube.com/watch?v=TIcW7sbA0hg

It does sound better than stock!

Greg

Nuke, you could be right. I was going off a few old threads at the Hoffman forum about this. There was the one below, and then another I can't find right now that said something about the 150V caps being really cheap because they were used for something else. In any case, they used to be very common...

The voltage multiplier power supply is an interesting choice technically, and I don't think it was because they were being "cheap" in choosing it. The stacked voltage doublers is actually based in cheapness. If you use the voltage doubler power supply, then the caps you need to use are lower voltag...