The 6550 Experience

[daveweyer]

I would have to agree that Jimi probably complained that the newer amps just didn't have the mojo of the older ones. That's exactly what he told me, and the primary reason I tried to optimize his amps. After all, when you stop to think about it, why would Jimi Hendrix have West Coast Organ and Amplifier optimize brand new amps, the latest greatest thing right off Marshall's assembly line?
There was a time, when Drake was building the power transformers, that an entire order of them was produced with the export primary winding set up for 110V. When you ran them on 120 volts over here, they could produce over 650 volts on the plates of the tubes. Those were some ballsy amps, and some real tube destroyers.
If Jimi had been using those, it is little wonder he would feel the new SLs weren't very kick-ass when he switched over to using the new stuff.
I'm pretty sure this is where all the mods got started.
And probably why he kept the old JTM models; I remember trying to set those up so they wouldn't destroy the tubes, but still have the balls.
There is probably about a 1:20 chance that Jimi was using one of those amps in New York, not great odds, but entirely possible.
A better chance would be that he was using a West Coast modded SL or bass that had some JTM DNA.

If you got flamed for thinking these thoughts, it's just because the Jimi story is kind of set in stone in the minds of many followers, and once the story is set in place, it CANNOT be changed without visual proof--everything else is a conspiracy theory--the visual proof being only photographic evidence, not testimony, unless it's Kramer or Mayer, who have somehow escaped critical analysis.

I think folks like a simple story, with all the details neatly wrapped up, all this amp changing and FF modding is too messy. Who knows, maybe all this talk of West Coast Organ and Amp will drive all the other followers away from this forum back to forums which just repeat the same old story, so they can feel safe with their beliefs. In that case Jimi will be like the god figure of different sects, the West Coast church here, like the Methodists, and the stock SL church over there, like the Lutherans, and whoever can get the most believers can assume they have won.......ha

[shakti]

Happy New Year, guys! Looking forward to some more interesting exchanges here in the year to come.

I think most of us guys in this thread are slowly reaching some kind of agreement. No need to stand on our own little soapboxes and shut our eyes and ears to what others believe - none of us know for sure and most likely never will know for sure. But we are slowly converging:

- whether it was a 69 SL, a SB or even an earlier model, most of us agree that it was probably not a stock SL.
- 6550s were very likely used
- the fuzz is crucial, but running it with the fuzz turned down at least a bit, and volume way up, into a Uni-Vibe preamp, helps to get the sustain boost without the over-saturated flab that a Fuzzface full on can bring. But I agree, this deserves a thread of its own...AFAIK no one has yet tried a full West Coast mod? That would be the next step for me.

I agree with Dave that the chance is probably something like 1:20 or even less that the "special BOG amp" was a true 45/100, but along with what Billy Batz has found, I agree that a few mods in that direction work better. In fact, the two mods that I've sort of ended up with - shared cathode and no V2 bypass cap - are perhaps the two largest differences between a later Lead preamp vs the earlier type! If you change those two, the whole topology of the preamp is exactly the same. The differences then are simply the values of the coupling caps, the values in the tone stack, and the amount of negative feedback, all of which tend to increase the gain a bit and focus it more in the mids. IMO a stock bass circuit (with the 27k@16 ohm NFB) does not get there, not enough gain/breakup), but that's with my setup and guitar, and my ears. If one wants to get argumentative about it, the DNA of *all* the possible variations we are discussing, is 95% Fender Bassman! And the differences are probably most apparent to the player anyway...

Billy Batz, do you have any photos of your amp? Curious to see how you have the switching laid out.

BTW, I stumbled upon a cool little trick yesterday; I had the amp chassis upside down, and accidentally plugged the guitar into the low input and used the high input to daisy-chain. Now if you plug into the low input alone it cuts the signal quite a bit, but contrary to what you might think, using the high input to daisy-chain you actually get a gain boost, and not a further cut! However, to my ears this was a different gain level than what you get when you plug the guitar into high and daisy-chain from the low input. Now was it more like BOG or less? I am undecided, but it's another little tweak to try.

I really feel like I am 98% of the way there with the specs I've landed on; lead amp with 47k/8ohm NFB, 6550s biased cold, 12AT7 in PI, 5000pF bright cap, shared cathode and no V2 bypass cap (but probably switchable, as it may actually be helpful depending on the room). As soon as I get the bright caps I've ordered, I am wrapping up my amp and will be playing it intensively until I hear from you about your other experiments with changes of power transformers, rectification, filtering and whatnot. And let us dedicate a new thread to details about the West Coast fuzz.

[Billy Batz]

That's pure fantasy which could work regarding this context and what we hear. Now he obviously also had some west coast amps for that night too.

I understand policing the speculation totally. But I also think theres room for pure fantasy. I dont think it is pure fantasy. Damn how crazy is it to think a guitar player would choose to use one preferred older amp for a live recording over another on a second night. Completely insane!

so your speculations got you to the point that you were fired from the plexi palace forum ? wow ! what a good example of how limited is the "go by evidences and proofs" way, which can't work much since anything can hide behind the cabs and head cabs ...

I wouldnt go that dramatically about it. The experience (and a few others that didnt necessarily happen to me) left such a bad taste in my mouth I chose to not be a part of that community. It was clear that like so many other forums, the ego's and king of the mountain mentality took over.

Why are we always coming to the Bog tone ? it's interesting. maybe because it was the most elusive tone Jimi got,

Sure its definitely that but not just that. If it was just a hard to emulate tone I dont think that would matter so much. Its also a tone I think 9 out of 10 people find amazing from the first note.

[Billy Batz]

If you got flamed for thinking these thoughts, it's just because the Jimi story is kind of set in stone in the minds of many followers, and once the story is set in place, it CANNOT be changed without visual proof--everything else is a conspiracy theory--the visual proof being only photographic evidence, not testimony, unless it's Kramer or Mayer, who have somehow escaped critical analysis.

I think folks like a simple story, with all the details neatly wrapped up, all this amp changing and FF modding is too messy. Who knows, maybe all this talk of West Coast Organ and Amp will drive all the other followers away from this forum back to forums which just repeat the same old story, so they can feel safe with their beliefs. In that case Jimi will be like the god figure of different sects, the West Coast church here, like the Methodists, and the stock SL church over there, like the Lutherans, and whoever can get the most believers can assume they have won.......ha

I think that about sums it up in a nutshell. To me it seems 90% of guitar players hear any old strat-through-old-marshall sound and think it cops hendrix

[Xplorer]

I understand policing the speculation totally. But I also think theres room for pure fantasy. I dont think it is pure fantasy. Damn how crazy is it to think a guitar player would choose to use one preferred older amp for a live recording over another on a second night. Completely insane!

Exactly, off course there is room for fantasy ! that's what i meant regarding my own theory with the fantasy 45/100, some others also ( like the reamping and feedback speaker meant for this ) . we shouldn't stick only to the "évidences" and proofs" , which actualy don't exist so much. + sometimes, the fiction goes further than reality.

I would have to agree that Jimi probably complained that the newer amps just didn't have the mojo of the older ones. That's exactly what he told me, and the primary reason I tried to optimize his amps. After all, when you stop to think about it, why would Jimi Hendrix have West Coast Organ and Amplifier optimize brand new amps, the latest greatest thing right off Marshall's assembly line?

If Jimi had been using those, it is little wonder he would feel the new SLs weren't very kick-ass when he switched over to using the new stuff.
I'm pretty sure this is where all the mods got started.
And probably why he kept the old JTM models; I remember trying to set those up so they wouldn't destroy the tubes, but still have the balls.
There is probably about a 1:20 chance that Jimi was using one of those amps in New York, not great odds, but entirely possible.
A better chance would be that he was using a West Coast modded SL or bass that had some JTM DNA.

That's precious to see that the bits of hypothesis and conclusions we gathered on the forum over the years, look like in the ball park, so well, regarding what you reveal. So we weren't so bad ! ha

If you got flamed for thinking these thoughts, it's just because the Jimi story is kind of set in stone in the minds of many followers, and once the story is set in place, it CANNOT be changed without visual proof--everything else is a conspiracy theory--the visual proof being only photographic evidence, not testimony, unless it's Kramer or Mayer, who have somehow escaped critical analysis.

I think folks like a simple story, with all the details neatly wrapped up, all this amp changing and FF modding is too messy. Who knows, maybe all this talk of West Coast Organ and Amp will drive all the other followers away from this forum back to forums which just repeat the same old story, so they can feel safe with their beliefs. In that case Jimi will be like the god figure of different sects, the West Coast church here, like the Methodists, and the stock SL church over there, like the Lutherans, and whoever can get the most believers can assume they have won.......ha

this is not hypothesis, yes, this is obviously reality

i'm waiting for the dynaco and hopefully, Dave's 6550, when Bill will be over his experiments.
i hope to hear some more clips of you guys, and expérimentations.

meanwhile, i'm sure we could evolve a lot on a parallel thread about the fuzz.
i have a modded fuzz according to what Dave explained but we could continue some stuffs on it.
Dave, what do you think ?

[Billy Batz]

Billy Batz, do you have any photos of your amp? Curious to see how you have the switching laid out.

Im sure Ive posted them here before but I dont think I have any taken now. Next time I have it out Ill snap some. May be a while though. Its nothing complicated. The V1 cathode is a simple DT switch, the bright cap a 3 position DT switch, the v2 cathode a 3 position DT switch and the stack a DPST switch that parallels a cap and resistor (the ones that are wired on the board dont have to "match" one can be the lead and another the bass/jtm values as long as the paralleled component makes it right)

BTW, I stumbled upon a cool little trick yesterday; I had the amp chassis upside down, and accidentally plugged the guitar into the low input and used the high input to daisy-chain. Now if you plug into the low input alone it cuts the signal quite a bit, but contrary to what you might think, using the high input to daisy-chain you actually get a gain boost, and not a further cut! However, to my ears this was a different gain level than what you get when you plug the guitar into high and daisy-chain from the low input. Now was it more like BOG or less? I am undecided, but it's another little tweak to try.

You dont have to daisy chain. Just plug an unconnected plug end into it. This is a very old trick. I forget who it was but someone (possibly Page or Beck) talked about that trick in an old interview.

I

[Billy Batz]

double post

[Billy Batz]

meanwhile, i'm sure we could evolve a lot on a parallel thread about the fuzz.
i have a modded fuzz according to what Dave explained but we could continue some stuffs on it.
Dave, what do you think ?

I dont want to hijack the thread about 6550s, more then it has been anyways, but can you quickly tell me the nature of the mod because I havent followed all the dozens of pages on this topic here. I dont need the mod Im just curious what its achieving. Ive gone in phases with fuzzes and I havent played with one regularly in years now.

That's precious to see that the bits of hypothesis and conclusions we gathered on the forum over the years, look like in the ball park, so well, regarding what you reveal. So we weren't so bad ! ha

You know this is exactly why I started posting here again after years. I own my own business and Im always workign now. I hate to admit talkign shop about guitar amps isnt a huge priority but Ive spent so much time experimenting with old amps, custom new amps, custom new 100% NOS amps and gear and the conclusions I came to have always been like my little bastard children I liked but never respected because I doubted they were right. Dave comes on here and offers validation so theres some symmetry to all this that obviously isnt coincidence. Its great and much appreciated. I just wish we had soemthing totally obtuse for this last bit

[Xplorer]

sure. we did some quick experiments in the beginning and left it for a while.

http://imgur.com/a/8a2wO

it does a lot of fuzz , or rather sustain, even with the fuzz gain down to zero. i had a little clip made. in the end only, i turn the fuzz gain up.
it's about a 20k pot instead of the 470 ohms and 8k2 resistors. Dave did some other mods too.
this one was just for a quick demonstration about the fuzz volume, and to give some perspective on how Jimi's fuzz arrived at west coast, all with their fuzz gain knob set close to zero or at zero.
this little fuzz doesn't feature the right transistors, input and output caps. it could be a lot better i'm sure.
and i'd like to try with some bc108c like on the blue fuzz, or do some other mods.

[Billy Batz]

Your second like just went to the main page at soundcloud

[Xplorer]

sorry :

https://soundcloud.com/xplorer80/141120-hendrix-fuzz

[bill bokey]

I really feel like I am 98% of the way there with the specs I've landed on; lead amp with 47k/8ohm NFB, 6550s biased cold, 12AT7 in PI, 5000pF bright cap, shared cathode and no V2 bypass cap

I'm pretty happy with these mods too, they work great with "Dave's settings" : V7, T4, M6, B4, P9. I actually keep the bass a tad lower but it would be different in a bigger room or outdoors. But the '73 Super Lead I used for my experiments wasn't a great amp to start with. And we know Hendrix never used one !
I actually sold that amp yesterday and just before I did I realised the grid leak resistors were wrong : the PPIMV was a dual 100K instead of dual 250K
So I swapped the PPIMV yesterday and then played a '70 Super Bass with the same setup and settings. The SB (with EL34s) was nowhere near JH's tone, well... for geeks like us !
Anyway, I think the lead tone stack works much better for the tone we're after, along with cold biased 6550s and a 12at7 PI.

Shakti, have you tried 2K2 screen resistors ? That would be one of the main differences between our amps. (And the filtering was lower on my SL73 as well, I'll try with a standard 69 50µF setup.)

I'll start experimenting again asap but with three new amps (all clones w/Marstran trannies) :
- '7026' 45/100
- Black Flag
- 69 Super Lead

And I'm also buying a "blue" fuzz face, a univibe clone and possibly a Dunlop Octavio (I read it's closer to the original than the Fulltone Octafuzz). And as I have enough cabs at my disposal I'll also daisy chain 2 stacks... I'll open a window, we'll see if Xplorer can hear me...

[Xplorer]

Hi bill ! that's fantastic ! three amps a fuzz and a univibe, wow ! good selection

i've never tried a Dickinson specs ( i was on my way to go for it but i changed ) . at some point, maybe try at least the stock values on the 45/100 , like 16 uf on the preamp, 1k instead of 470 ohms on the screens, 250pf / 56k instead of 33k / 500pf .
and maybe, see what's closer ?

will you transform the 69 SL into west coast ?

[bill bokey]

Yep, the SL69 I intend to "west coast".

I'll try various setups on the 45/100 but from all I read and heard JH seems to have always used the lead TS. I know I prefer it with a strat but we'll see !

[Tazin]

I don't know why people would have a tough time accepting the idea that Hendrix might keep some of his older gear after purchasing new stuff....There's that one picture showing Jimi playing a late '66 JTM 45/100 in mid September of '68, so it's apparent that some of his gear hung around for awhile. It looks like Hendrix used his newer amps for live shows and probably used his older stuff for practicing and maybe studio work.