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

[Xplorer]

The two jacks on the back of the Quantum amp allowed Jimi to use the preamp stage to drive Fenders or Marshalls, or to use the power amp section to take signals directly from the speaker outputs of a Fender or Marshall and re-amp the signal into extra speakers. He could actually do both at the same time.

very nice ! i'd love to experiment with such machine. how is it manageable to send 100 - 150 watts into the power section of an amp ?
and is the preamp of the Guild, basicaly sending the same signal and voltage amount, to either his own power section or the preamp of a marshall or fender ? or would the signal sent to a marshall need some adjustment ?

i remember once, brian wallace from marstran, helped me to check my 45/100 preamp, and it was feeding the power section of a superlead. or on the opposite, the preamp section of the superlead feeding the power section of the 45/100.

now using a preamp to drive another preamp, this sounds a must to test !

[swankmotee]

And isn't it ironic how the iconic players like Jimi,Holdsworth,ect are forever searching for their sound but have the most incredible signature sounds! Boggles the mind!

[Tenderfoot]

daveweyer wrote:

So I guess there's a rhetorical question in all this, do most of you who are regular readers and contributors to this forum know that Jimi was actually pretty dissatisfied with his limitations of a FF, a Wah, and maybe a Univibe for his musical performances?

For some reason I always felt like given time, Hendrix would have taken the direction Jeff Beck has.

[Xplorer]

And since I'm boring you with all this I'll also broach the controversial subject of Jimi's tone at what seems to be the height of his performances. From what I've seen, most of you have gravitated to this tone as the ultimo-primo tone to die for and keep forever, since that is what you heard during those last couple years of Jimi's life.

do you really think you're boring us with this ??
some other tones to die for are imo these amazing clean tones like on the intro of "one rainy wish" ( not the octavia guitar, but the perfect stratocaster tone he's got ... damn, how did he get that ?? ) , angel, drifting, or a tad crunchy like on little wing, castle made of sand ... or the Berkeley tone ( but it's actualy not difficult to go from bog to Berkeley, it's not very far if you adjust your settings a bit, i think ) . also the chaos mastering in some lives of "are you experienced"

it's been said that Jimi's sound city one hundred played a nice role in it. Shakti, i think, talked about it and built a cp103 ( later version but very close, to the sound city ) . thorleif, if you have some clips like the intro of one rainy wish, and other stuffs, that would be fantastic

damn you're right swankmotee, but it's understandable with the saying : "artists are never satisfied with what they did .. " allways looking further. But of course if they didn't appreciate enough what they did, maybe they wouldn't continue, so i'm sure such musicians or artists do appreciate what they have at some point. Yeah, too bad Jimi didn't live longer to discover all the thousands of various toys we now have, and which started to expand after he passed. but i think that it could have weakened his creativity after a while.

right now, hearing a little band on tv, i see that they don't propose something revolutionary at all. just any guitar cool looking, in the tiny amp they've been told to use, with not perspective on their tone, no personality. it's just basic stuff, and bands like this today are the majority i think.
now those who had / have some amazing signature sounds, they started with big constraint, having not much tools compared to today, to express themselves. so they pulled the most out of what they had, even in some unthinkable ways.
that engaged a lot of creativity. i can understand that they wanted more, that they had sounds in their head that didn't exist yet ...
now, guys like Zappa, i think that even if he got more toys later, it still applies to him a lot ! Gilmour .... sure, jeff beck , VH, even billy gibbons ...
i wasn't born back then, but i'd define this as "the old school way", am i right ?

by the way, looking at this Guild amp, with the unique features it has, i Wonder if i could perhaps implement it on my current 45/100 build easily ? this one will be all about cool mods and switchs anyway so ... if i can put that on my list ....
then i could drive another 45/100 or any amp, with the preamp of this one.
would some peoples like to work on such project for yourself already ?

[daveweyer]

Of course you have to cut the signal down to size to come out of a 30 volt source like a speaker output and go into a power amp input with a 1 or 2 volt sensitivity, but you can do that with a simple resistor. This process, which Gary Rowles calls "gain staging" is worked out with just a couple pots, depending on whether you want to run a preamp into another preamp, or a speaker output into another preamp.
I, for one, have never heard anything equal the sound of a speaker output into another preamp for a multi-dimensional feedback path and long beautiful sounding distortion and sustain.
But a lot of you will have probably listened to more distortion devices than I ever did.
Gary Rowles told me he learned gain staging from Jimi, so it's pretty clear that Jimi knew about it and tried it.
But as I've mentioned too many times, the signature sound that so many have had throughout the musical scenes which lived during technology and electricity, have been products of accident, economy, and convenience.
Jimi, for instance, just picked up what there was around him and tried to get it to do something new. Surprising when you think that Jimi had no more to work with than any other player of his time, so how come he took a Fender Stratocaster, which was designed for a kind of jazzy cleanness, played through amps which weren't intended to distort, and turned it into a sliding feedback monster through amps which were in complete distortion, and then played that feedback like an organ for sustained musical tones?
Why did he do that when nobody else did, and they all had the same equipment?
And in the end, what was his signature tone, how was it different from others who used the same equipment, and did he really mean it to be his signature tone, or was it just because he didn't have any other equipment to make a signature tone with?

[Xplorer]

cool, so i'll work on this mod, with you if you're willing to help me . i think i should first make sure it works fine, stock, then start the mods.
i'm not sure to need the over way though : feeding the power stage of a 45/100 with the preamp of another amp, for more cabs.

i suppose that Jimi followed his ears, while he was looking for more power, louder cleans with a nice personality for loud blues, and magnificent chaotic saturations for other things. and it came up like that, a bit by accident, to later be more a choice, and controled.
And this, when the fashion was "the shadows" tone, super clean. that's when link wray came in with a bad boy wicked sound, if my history is good. well, Jimi came after that but still valid.
also, that's when the first 100 watts guitar amp started to exist.
i guess the others were after something else, looking for loud, but not necessarily clean loud like this.

[yladrd61]

Jimi was definitely headed in a new direction with his music Ezy Ryder, Izabella, Freedom, Straight Ahead, Hey Baby, Angel, Message of Love, Machine Gun he was using less and less fuzz, and more clean boost, and the Uni Vibe it was so totally different than the first 3 Albums, and his live sound was totally different, and sometimes he still had problems with his rig, as he did at Isle of Wight..... We can only imagine what might have been if he had been able to really use all that Electric Lady had to offer !!!!

[daveweyer]

That's kind of my take on it too. I really sensed Jimi was searching, and was pretty dissatisfied that he couldn't make the breakthroughs that he did when he first took everyone over the mountain.

One of these days I'm going to offer a glimpse of what he was trying out in those days to catch a new wave. I have some audio tape of some of it which I think the loyal Jimi fans of this forum would really like.
He seemed to be heading two ways at once, refining the old feedback stuff, and doing a lot more cleaner playing based around his improving technique.

Anyway, If I can find this old tape you'll get to hear the Davophone in action!

The Davophone, if I haven't already said this, was named by Deniz Tek of the Australian rock band Radio Birdman. It was a little more friendly title than the "tube modulator".

Someone wanted a schematic of the modulator; I'm not sure it would mean anything to forum readers because of its unusual circuitry, but I'll post it if you like.

[mmp31]

Someone wanted a schematic of the modulator; I'm not sure it would mean anything to forum readers because of its unusual circuitry, but I'll post it if you like.

Yes, I would like that. It sounds like a fascinating device. Thanks Dave!

[fakeox]

My 1st post. Thank you Dave for your thoughts & memories!

[daveweyer]

Okay mmp31, I'll get a schematic posted of the tube modulator. It won't show the mods because I added those later and they probably won't matter anyway for purposes of introducing the concept.
The main thing to know is that Jimi would have used one of these things if I would have had an extra one to let go. But I didn't and the rest is history. But I do have some audio I can share if I can locate it, then you can hear what I heard and get an idea of where Jimi might have gone if time would have allowed.

[Xplorer]

Wow !! Dave is so kind to share some more great stuffs, here are the schematics for the Tube modulator, and the Quantum amp !

http://i.imgur.com/GtKqLWp.jpg

http://i.imgur.com/VAO58W5.jpg

[Xplorer]

a tad darker version of the tube modulator, for better visibility in some points.

http://i.imgur.com/5KIBbgs.jpg

[daveweyer]

Well I'll comment on these schematics Xplorer posted just in case it means anything to you.
The Quantum amp:
You can see some extra sophistication in the output circuit say as compared to the Marshall. The bias for each output tube is adjustable so you can give them equal current draw at idle. Not only that, you can also measure the cathode current of each output tube, from outside the chassis no less. That's what the two 6.8ohm resistors are for. Those also allow the output tubes to self bias themselves slightly to account for changes between tubes, and aging. They also allow a tiny bit of current feedback in each tube, lowering their gain just slightly.
You may notice that the circuit is a classic Williamson design, gain stage, phase inverter, output stage, and feedback around the output transformer. This is the same design Marshall used in its PA equipment, where less distortion was desirable.
The grid bias resistors are only 91K, which is a much safer design for high power output tubes. But to use that low of a value you have to use a 12AU7 as the phase splitter, in this case what is called a split load phase inverter, where the two out of phase signals are taken from the plate and cathode of the tube and the loads are equal, at 15K each.
They use a 7247 tube which has a hi mu section and a low mu section. Very Ampeg.
Also notice a voltage doubler power supply, a trick some of the high-end audio folks use to lower the impedance of the power supply--lots less resistance in the windings.
And of course, the big feature is the 6GF7 screen regulator tube, which provides a very quiet and stable 300 volts for the output tube screen grids, something they appreciate very much.
If you remember my explaining that the plate signal spends a lot of time below the potential of the screen, causing the screen to draw a lot of current, you may see why they provided a lower screen voltage. Now the plate signal is lower than the screen about half the time instead of most of the time, which causes screen current to fall dramatically.
Of course that also lowers the sensitivity of the tube, which is why they used 8417 tubes. They have a transconductance twice what an EL34 or 6550 has, meaning they pull twice as much current for the same input signal.
You really can't use these tubes in a Marshall unless you lower the screen voltage. I know, I must have tried it a dozen times; it's the loudest damn thing you have ever heard, but it won't last a week.
You probably recognize the input stages, classic Fender with a simpler tone stack but contour switches for high boost and so on.
The bass channel is contoured for bass guitar.
Anyway, hope you enjoy it. Jimi liked it enough to keep it through his whole career.

[Xplorer]

Guys ..... this is a great moment , i can't believe my ears ....

i'll let Dave talk about it .

satisfy your ears, this is from another galaxy ...

https://drive.google.com/folderview?id= ... sp=sharing