Jimi Hendrix' Gear and Mods at West Coast Organ and Amp

[Tazin]

Anything that Marcel posted on his facebook page regarding the amp is public domain and the same basically holds true for the stuff published in the Univibes magazine. My "respect their privacy" point was geared towards reaching out and trying to contact Marcel or the museum and hound them for more info. Put yourself in the owners shoes...How would you like it if day after day, year after year people try to contact you and ask you for info/pictures of your amp? As the owner you stand to gain nothing, but as the recipient of the info you reap all the benefits. Then there's the whole possible exploitation thing where everyone and their brother will be selling "Hendrix clone" amps on ebay now because this.

[Tazin]

Getting Dave in contact with the owner seems a very reasonable way to go about things though - if Dave agrees, that is.

Getting any additional info on this historically significant amp is most interesting, even if it's not going to be earth-shattering if Tazin has the right info. Any little hints on tweaks that may or may not have been done would help us one further inch. The only other allegedly Hendrix 69-era amp we've seen inside photos of does have some little tweaks, and it would be interesting to see if 10590 has tweaks in the same spots (shared V1 cathode, different first stage coupling cap, different V2 cathode bypass cap, bias circuit value changes probably to accomodate 6550s etc).

All the Hendrix 69-era amps I've seen have the same basic circuit. Some have had more changes over the years (i.e. 12361) which are easily identified as post Hendrix modifications. Earlier in this thread (somewhere) I mentioned what the outline was for this basic circuit.

[daveweyer]

Maybe Tazin knows about this: Supposedly it was during 1969 when all the Hendrix gear was stenciled with the familiar J.H. EXP, I have read that info several places. But in the early spring of 69, when all Jimi's gear came in for upgrades and repairs, the big black metal box with wires, guitars, and pedals inside, was already stenciled. The New Marshalls were obviously not stenciled yet, and for all I know we may have been asked to do it. So it seems to me that the stenciling did not all happen at once, and there may have been slightly different fonts used depending on where they were done.
The picture of me installing 6550 output tubes in Jimi's gear really wouldn't prove much since the cabinets weren't all marked up yet, and there weren't any stencils on the heads, unless some of those 45/100s had already been stenciled and were sitting beside the bench or in the background. I haven't actually seen the photo yet, but it makes me wonder how much it would be worth.
I used to complain to Jerry about putting West Coast stickers on all the equipment; I thought it was tacky, and beneath real professionals, after all Jimi would know where we were and how to get in touch with me. Jerry of course insisted, and I reluctantly complied. Now I look back and think, holy shit, if we hadn't done that nobody would know!

[Tazin]

John Downing (roadie) was the guy who did all the stenciling starting in December 1968 or January 1969. He was the one who actually created the stencils too.

[daveweyer]

Xplorer, should we post the exact schematic of the prototype 3 transistor Hendrix fuzz that the museum bought, just so folks could try building it from scratch? They may discover some good sources for NOS 2N591s and other things for the circuit.

[Xplorer]

Xplorer, should we post the exact schematic of the prototype 3 transistor Hendrix fuzz that the museum bought, just so folks could try building it from scratch? They may discover some good sources for NOS 2N591s and other things for the circuit.

Dave, didn't you made me post it already ? i think it was the base i used to start my clone attempt but something was wrong in my build or in the schematic, i don't remember so well what it was all about now, but yes, it should be interesting, it's up to you.

[daveweyer]

That circuit was a little different. This one has all the voltages, betas, and other info to dial in its operation. I didn't have the actual Jimi prototype when I did that circuit, but if you copy the prototype it works perfectly. Might be easier than trying to get the other one to work right. They are a lot the same, but certain things are different.
Anyway, someone asked about it earlier so I thought I could offer this much for help if anybody is still interested.

[Xplorer]

Sure that's a good idea Dave ! then let's go for it if you like. Do you think there's a way to mod the one i sent to you, so it would be just the same, rather than fixed, since you think it's not ideal the way it is now ?
i wouldn't say no to such fuzz from you ! i just don't have the right pieces, and last time i didn't have the right transistors too if i remember. i'd also love if i could get such version come from you Dave please, if it's not a hassle.

[daveweyer]

I'm not sure how you post a freaking picture right on these pages, because they sure don't like JPEGs or PDFs or TIFFs and other forms. If you choose add an image you just get text on the message. But it must be possible because others can do it, just not Xplorer or me.
Anyway, I wanted to post the schematic of Jimi's 3 transistor fuzz, the one that the museum purchased for the Jimi gear display.
So I'll just ask Xplorer to post it as a link to his cloud account until someone can share the secret of getting an image right on the post page here.

[Xplorer]

I'm not sure how you post a freaking picture right on these pages, because they sure don't like JPEGs or PDFs or TIFFs and other forms. If you choose add an image you just get text on the message. But it must be possible because others can do it, just not Xplorer or me.
Anyway, I wanted to post the schematic of Jimi's 3 transistor fuzz, the one that the museum purchased for the Jimi gear display.
So I'll just ask Xplorer to post it as a link to his cloud account until someone can share the secret of getting an image right on the post page here.

hi Dave ! Sure, here is the picture you sent to me. The way i do it is to add the photos on a personal third party image bank, then i post the url and put it into some IMG html code. you can do it or ask me, not a problem for me.
thanks for sharing this !

[daveweyer]

Hot dog, well at least it's right here for everybody who thinks Jimi might have had an "always on" circuit in his signal chain. Now all I have to do is get a couple like this one up and running for folks to try; I'm looking for a set of transistors with the right hfe and 2N numbers.
This circuit has a special sound, even though it has poor temperature stability, but with all those controls you can dial it in unless it is really cold.
At minimum fuzz, it is just an amp, although there is a little crunch to it.
Thanks to Xplorer for getting this posted.

[neikeel]

Might have a play at one of those

Anybody advise where I can get transistors at specific specs?

- last ones I got from Stu Castledine for a specific Tonebender project to his specs

[Roe]

I'm also interested in transistors and parts (and I guess Shakti is too)

[Xplorer]

if possible, i'm in too !

[Tek465b]

I love the changes you made to the bias circuit.
Am curious, why the 26V reed relay?(i guess part of another circuit).

Now to match the transistor you need a few of them. I looked around on ebay and there is some 2N525 and 2N591
Prroblem is they sell about 15-20$ each and to match/select the HFe, we need a group of them to make a selection.

I do have about 30ish AC127 in that same HFe range. They are the ones here on the right with the Gold legs:
http://www.mediafire.com/convkey/3a1b/9 ... 8tjc4g.jpg
Yes the one on the left are AC128 but they are all very low HFe, just good as diode.

So i can design a NPN version of the PCB(for 1950B and 125B enclosure), and provide some AC127(limited quantity) if that can help.
The PCB can still be used as PNP just reverse the Capacitor and power supply polarity.
TO1 and TO5 package are the same pinout if am right?.

Is that a good idea? Or make the PCB PNP(positive ground)?
Am ready to design/order a small batch of 5-10 pcb.