Metropoulos Forum

I'll answer tomorrow as soon as I get a minute--I'm sure you all can hardly wait!

Tone seaker wrote: ↑

Sat Nov 28, 2020 7:06 pm

looks like he used big and small bottle tubes
https://www.bing.com/images/search?view ... ajaxhist=0

They are clones made by Pineland Monster Boutique Amplifiers as part of their 2020 Jimi Hendrix Tribute Series. They look cool but they could/should have been more accurate for the money.

The Hendrix Foundation is also tentatively planning some Jimi tribute amps, but the idea is to have them capable of going where Jimi was headed instead of just where he was at the time. Based on our shared ideas of what he wanted to do and circuits I showed him that could do other things, there would have been sounds beyond BOG.

This brings up the Supro 6420 concept. After I showed him the mods in the Supro and he heard what they could do, he was all about either modding his Marshalls to get that sound, or building new amps. I started one of the new amps for him as a pilot amp but he died before I got it finished-- I still have it sitting on my piano, waiting.

Anyway, the Supro was just a cheap Valco amp but it had a spare tube slot, so I used it to put in a cascode amp stage. Cascode amps were used in television tuners as RF amplifiers because they had high gain and extremely low noise, but their side effect was a very high degree of even harmonic distortion (guitar player's ears perk up!). The sound of the guitar through the cascode amp was something he had never heard, but he immediately picked up on it, being a rather visionary sort. From there the discussions began about taking the concept to the extreme, as was his character trait. We could do a iife-time of amp building all in an after-hours chat at the West Coast Amp shop, that is, after we finished talking about God, and sex (and heating up that resistor).

The question the Foundation is asking, is whether or not these amps should look exactly like 69 Marshalls, or be something entirely different, since there are so many Marshall clones out there, it is a logical question.
I think they ought to look different, since they can do what Marshalls can't, but the discussion goes on.
It is sort of BOG and beyond, and I'm quite sure some folks out there would like to know just what "beyond" sounded like. You can get an idea if you can find Jimi's modded Supro, but it probably got trashed years ago.
I built a prototype of the modded Supro Jimi amp in a V-47 chassis for Vintage 47 amps and the Foundation, since Vintage 47 makes clones of the Valco amps, it was a lot like the original. It had some guitar players shaking their heads.

So that's a bit about the Supro mods.

did his wha pedals have some kind of buffer added, My 69 V846 sucks the highs off terrribly thks

The pedals I did for him had an output resistor of 10K and then later 1K. But the lower noise and response comes from the Motorola 2N5089 transistors. These perform much better than the 2N3900 GE units that Vox used. Like, way better.

so they were not true bypass and still sucked the highs down like mine does thks

No they were actual hardwire bypass, and I don't think they sucked the highs down, at least the pedal of Jimi's I had here didn't.

the originals are not true bypass were jimi's modded to be true bypass not pulling highs off or were they original except the resistors you mentioned. To make them not suck the signal you have to put a different swithc in a 4 pole it think its called was this done. thks for the help just trying to dial in my rig

Well you had me scratching my head, but I just looked up the original V846 wah circuit in the Thomas Organ manual, Thomas # 38-5500-0. It is a true hardwire bypass, switch S.P.D.T. directs the input signal right to the output jack. The only thing that could affect the signal is Q1, because its base junction is hanging off the input jack though a .01 cap and a 68K resistor. If Q1 is a low beta transistor, it might load the guitar pickup just slightly. Try a 2N5089 transistor in that spot And, it will run on a lot less base current, so the resistor value could be increased if needed.

daveweyer wrote: ↑

Tue Dec 08, 2020 10:16 pm

Well you had me scratching my head, but I just looked up the original V846 wah circuit in the Thomas Organ manual, Thomas # 38-5500-0. It is a true hardwire bypass, switch S.P.D.T. directs the input signal right to the output jack. The only thing that could affect the signal is Q1, because its base junction is hanging off the input jack though a .01 cap and a 68K resistor. If Q1 is a low beta transistor, it might load the guitar pickup just slightly. Try a 2N5089 transistor in that spot And, it will run on a lot less base current, so the resistor value could be increased if needed.

from what i have read to be true bypas you take out the SPDT switch and put in a DPDT switch because the orig goes partialy theu the circut with the SPDT. is this correct? Did Hendrix have the orgianl SPDT switch or was it changed to a DPDT? thks

Hendrix pedals had the S.P.D.T. original switch. It was the transistor change-out that got rid of the loading. But, to get EVERYTHING off the input jack, you need a D.P.D.T. switch which also lifts the base of Q1 off the signal when the bypass switch is pushed.

The new Haleakala audio is much improved as is the very limited video, Jimi goes places that are beyond Berkeley , he has a dark colored fuzz face sounds different than any other I have heard him use

wow, I just read all 105 pages of this thread!

fascinating!! thanks to Dave for posting all this great info

long ago, when I got my '66 jtm100 I initially had it running 6550 tubes, and was surprised how great it sounded: also how good the clean Hendrix stuff sounded through it. But I discounted it because I didn't think they belonged in there. ha! I had to laugh when I read about the 6550 tubes installed in his later amps.

If you could have reliably sourced KT66 tubes would you have considered using them? not sure how available they were in the US

Also apparently Jimmy Page had 6550's installed in his Marshall's, do you know anything about that?

I have a blue Dunlop JH fuzz here somewhere, will have to try the fuzz mods

anyway thanks again, it's really fun & interesting to read anecdotes from people who were there, back when all this creative stuff was happening

I typed a reply to this and it said my post was waiting for mod approval...just checking to see if this works yet!

is this you Dave? si the inly mods to his wha was the restor to control the fuzz from squealing and the cap underneath to makee it darker.. it sill pulled the highs down like other whas. Were all his whas TDK inducors thks

https://www.youtube.com/watch?v=T23o4Lu ... inegedroyc