The 6550 Experience

[daveweyer]

I think Tazin's got a pretty good idea. Why not an A/B between the amps? If there really is a difference worth shouting about, it might narrow the parameters a bit.
If there were unmodified amps they would most likely be from before the big 69 tour, although we were still doing mods before that; but it would still narrow the field a bit.
Wouldn't want the differences to be just wishful thinking......

I'd also like to know what the general feelings are comparing the original Tung Sol 6550s with what you experienced with the new foreign units.

[Tazin]

Xplorer, I agree with you....The stuff I mentioned would be better off in it's own topic rather than steering this topic off coarse.

[shakti]

old clip. it's surprising how both amps ( west coast mod superlead and 45/100 ) get in the ball park.

so playing on what they have in common now ( such voltage setup, tubes .. ) looks like the way to go. + shared cathode. + .. ?
+ the right fuzz i think and the right speakers.

https://soundcloud.com/xplorer80/who-knows-noodling

The most obvious thing your 45/100 and a West Coast SL have in common is a different tube than EL34. The KT66 and 6550 both have more of that "big glass" tone than the EL34. But I still hear more overdrive with the BOG recordings than a typical 45/100, and the clincher for me is that there are many obvious moments during BOG where he isn't using a fuzz. And since the fuzzface was always a true bypass unit, right from the start, I don't think it's affecting the straight in sounds that we hear on BOG (Who Knows, Them Changes, parts of Stepping Stone).

As for shared vs split cathode, I've found that difference to be very small previously, when I had them both on a switch in a '72 SL I used to own. But I'll try to put them both on a switch, and record a clip showing different combinations of V1 cathode, volume bright cap, and V2 bypass cap.

There are several other obvious differences too, that are much more important differences between earlier bass preamp and later lead amps; different filtering altogether, different tone stack, different value coupling caps, more voltage dropping resistors in the preamp.

But in the end, the results matter much more than the specs on paper, so by all means, choose the route you want to take to BOG-land! But since you already have a Super Lead build, Adrien, why not join the gang and start some 6550 experiments of your own?

[shakti]

I think Tazin's got a pretty good idea. Why not an A/B between the amps? If there really is a difference worth shouting about, it might narrow the parameters a bit.
If there were unmodified amps they would most likely be from before the big 69 tour, although we were still doing mods before that; but it would still narrow the field a bit.
Wouldn't want the differences to be just wishful thinking......

I'd also like to know what the general feelings are comparing the original Tung Sol 6550s with what you experienced with the new foreign units.

Dave, as I just mentioned I'll try to record a clip A/Bing between different combinations of
1) V1 cathode (shared vs split)
2) Bright cap value (none vs 5000pF vs alternate value)
3) V2 bypass cap (none or .68uF)

BTW, I don't mean to nag you about it, but did you see the amp photo I linked to? I think it was posted in the other (original) thread as well, but I thought it interesting to see an amp which looks like it has been through West Coast (shadow and some glue remnants of a possible sticker), has JH EXP stencils and four output jacks. Do you recognize any of the work inside?

Lastly, if you have any more original Tung-Sols to sell, I could be interested in making a comparison myself.

[Xplorer]

Yes thorleif, I'm currently finishing a 45/100 which will be modded like a 6550 superlead, with, 12at7 and 100 uf that Dave kindly sent to me, also a dynaco OT i purshased for this purpose. And i hope i can buy some tung sol 6550 to Dave too for this amp. Actualy Dave mentioned that why not testing the 6550 sent to Bill while they're in France so we'll manage that.
yes t'll be tested, and why not calso ompared to my stock superlead 69, and 45/100 since this idea came up.

The 45/100 has more bog DNA to me, regarding the frequencys, the personality of the amp, and it can be much more gainier, if needed, delivering unmistakable bog stuffs which maybe don't appear in my clips.
i'm very excited to hear such good results with the west coast superlead. It'll be my third amp.

From this base, yes anyone has its way to bog, and now we have two ways, spot on, with common things in their architecture. then, i think that the fuzz has to be looked in a different way than off for cleans and on for wild stuffs. i don't think it's as obvious as we could think, that the fuzz may be completely out of the circuit. indeed, the cleans can be obtained even better while the fuzz is in the circuit rather than out. i know it's quite paradoxal.
I'll test things and see how good the clean and wild tones compromise makes the most sense, i have some feelings and hopes in a direction mentioned previously, which doesn't differ with what Dave said a few times. so more cool hypothesis and clips will rise i'm sure.

Very exciting results guys, congrats, keep going !

[daveweyer]

Shakti,
I looked at the amp photos again and can tell it was a West Coast visitor, but I can't see the values on things very well. The PI looks to have the 470 and the 10K, so that leaves the stock values there. Red varnish doesn't tell us much, we all had it.
The cathode bypass on V1 looks like one from our supplier, but I can't tell on the VC bypass ceramic disk cap.
We also had Wima caps, but I can't read the values on those. There are American style resistors, but apparently Marshall used some of those--at least there was one post about it.
The transformers look to be the stock ones, but that doesn't mean they aren't changed out for better ones. I'd also love to see the HV cap values.
This amp would probably be best suited to a measurement suite. I might be able to claim something more specific then.
I'd lay odds it had the 6550s though--they often broke off the retainers.

[daveweyer]

One more item about the archive amp, it has that kluged voltage selector with the Dymo tape label; that would be par for the course for making the amp into one playable overseas. I think we did a number of those changes on export Marshalls, for quite a few bands.
Take a good look at the bias section too, some amps you could get enough negative voltage for 30ma on the output tubes and on others you had to change a value or have the variable resistor all the way at the end.
And one more thing on the mods, if an amp sounded just perfect, THAT was the mod, except for the output tubes.
I remember finding two of Jimi's Fuzzface units which were so perfect that nothing you could do would make better, and I always scratched my head about it--it was a real good lesson in not modding just for the sake of modding.
Your ears, gut, and heart always had to lead the process, unless you were the owner of the business who just wanted some profit on every job whether the unit needed an upgrade or not.
That's my advice here too, no matter how cool something is or seems to be, just follow your ears to where they take you, even if it means Chinese tubes or new silicon transistors--everything has to subordinate to the brain's uncanny ability to hear specific characteristics.
So much dazzlingly complex interaction goes on in an amp, it's so dependent that even age can totally change the sound of something. Which really means that an absolute duplication of an original amplifier, an original FF unit, original curly cords, and original speakers, will not give you the exact sound you heard as recorded in the late '60s.
There are too many dependents and variables.
My friend, Bob Hovland, whom I have mentioned a number of times here and who was an engineer at Vox, JBL and Marantz, tells the story of trying to match an original Peerless output transformer for his highly regarded Hi FI amps, going to the extreme to have the original wax paper remanufactured to insulate the coils, and finding out that the paraffin based wax actually made a difference in the sound, and, that his paper manufacturer used a different wax formulation from the original, not having a clue that something that minor could possibly make a difference.
In other words, you don't know what it will take to get that original sound--it might not be the original equipment you think--age and a million other factors are going their own way. Even old wax sounds different than new wax of the same formula. A bit of a magical and mysterious world this sound business...

[daveweyer]

Shakti,
About that "big glass" thing. Just in case somebody has a few minute to read all this. I borrowed from Wiki on part of it, but elaborated to make it clearer, I hope........

KT66 is the designator for a beam tetrode vacuum tube introduced by Marconi-Osram Valve Co. Ltd. (M-OV) of Britain in 1937.

The KT66 is the direct descendant of the “Harries Valve” developed by British engineer J.Owen Harries and marketed by the Hivac Co. Ltd. in 1935. Harries is believed to be the first engineer to discover the “critical distance” effect, which maximized the efficiency of a power tetrode by partitioning its anode (plate) at a distance which is a specific multiple of the screen grid-cathode distance. This design also minimized the interference of secondary emission electrons dislodged from the plate by accelerating electrons from the cathode, electrons which would then find their way back to the screen grid and cause it to over dissipate.

EMI engineers Cabot Bull and Sidney Rodda improved the Harries design with a pair of beam plates, connected to the cathode, which substituted for the third grid in the valve called the suppressor, and directed the stream of electrons through two narrow vertical slots just across from the seams on the plate, the area of the highest dissipation, discouraging the dislodged electrons from the plate from returning to the screen grid through an effect called “space charge”. Space charge is produced by the slowing up of electrons traveling from a high potential screen grid to a lower potential plate, as happens when the tube is conducting heavily and the plate being therefore at a lower potential than the screen grid. In this low velocity region, the space charge is sufficient to repel secondary electrons from the plate and to cause them to return to the plate.

The beam tetrode design was also undertaken to avoid the patents which the giant Philips firm held on power pentodes in Europe, pentodes being tetrodes with a third grid, called the suppressor, which was also added to the tube to discourage secondary emission from the plate. Because this overall beam plate design design eliminated the “tetrode kink” in the lower parts of the tetrode’s voltage-current characteristic curves (which sometimes caused tetrode amplifiers to become unstable), M-OV marketed this tube family as the “KT series, standing for “kinkless tetrode”.

A number of different tubes were later marketed by M-OV. Some, but not all, were versions of existing American beam tetrode tubes or European power pentodes, the beam power tubes being the KT66 (6L6), KT88 (6550), and KT63 (6V6), and the power pentode being the KT77 (EL34 and 6CA7).

Although the RCA 6L6 of 1936 (the result of a license agreement between RCA and M-OV) was the first true “beam power tube” on the market, the later KT66 became almost equally famous, at least in Europe. The two tubes were nearly interchangeable, except that the KT66 was somewhat more rugged than the first 6L6, which was an all metal tube. Soon after, RCA produced a new more robust version called the 6L6G, which was housed in a shoulder glass envelope and proved to be extremely durable.

So when you hear a difference between “big bottle” glass, and the EL series power pentodes or 6CA7, you are hearing the difference between a beam power tube and a power pentode. Also, when you see the plate seams of a power tube turning red before the rest of the plate, you are seeing the result of the focused electron beam from the beam plates directing the electrons along a narrow pathway right at the seams of the plate, telling you the tube is a beam power tube.
In the end, the beam plates won out for sheer efficiency and ruggedness, but the tubes are much harder to match than power pentodes because the variability is much greater between tubes.
The beam plate design and the “critical distance” formula have lasted the entire life of power output tubes, all the way from 1936 to today’s KT120 designs.

It is fascinating to note though, that a new design emerged from the television industry in the early 50’s when television engineers realized that existing power tubes were insufficient to handle the duties of magnetically deflecting the electron beam in television picture tubes, or ‘sweeping” the electron beam across the screen to form multiple lines of an image. They began to classify this tube as a separate form, called “horizontal deflection amplifiers”. The characteristics of this type changed the original “critical distance” to place the screen grid very close to the cathode and move the plate closer to the cathode as well, to make the cathode much heavier and the tube heater draw much more current for greater emission, to provide a large seam at the plate joints for much greater dissipation, to add large radiators on the screen grid for more screen dissipation, to narrow the beam plate openings, to provide “dimples” in the plate along the seams to capture more electrons, to use more metal in the plate for more surface area, and to use better quartz glass for longevity under hot operating conditions.

As these deflection amplifier tubes evolved, the distances were changed again, and a new plate form showed up which actually had a cavity at the seams, and internal plate fins which were extended all the way through the beam plates to attract electrons directly from the screen grids. Because these fins were edgewise facing the screen grid, the electrons flying from the screen grid would not dislodge other electrons from the plate because the surface area of the edge of the fin was so small—the electrons would be captured in the plate cavity safely on the other side of the beam plates. All this made for HUGE efficiency gains, and drastically lowered the possibility of over dissipation of the screen grid, allowing now the sensitivity of the tube to be so great that the screen could run at 120 volts above the cathode potential—also, allowing the screen to be at a lower potential made the plate operate for much more of the cycle at a higher potential than the screen grid.
A typical horizontal deflection amplifier of the day, say the 6DQ5, would draw twice as much current as a 6550 with 1/3 of the screen voltage.
The final designs of this type in the final days of tube development saw both internal AND external fins on the plate at the seams for even more dissipation, the tubes in the pics of Dave Farrell’s bass amp that Xplorer posted show the external fins nicely. These tubes can draw 2 amps of cathode current each, four or five times what a 6550 can draw.
One tube of this type, the 8417 was a horizontal deflection amplifier with a plate cavity that was modified for more turns of wire on grid#1 to make it even more sensitive, and presented to the world as an audio power tube. It was used in Bogen equipment, some Hi Fi gear, industrial amplifiers, and used also in the Guild Quantum amps just like the one Jimi Hendrix owned and is shown with the West Coast Organ and Amp mods in the pics Xplorer posted.

Anyway, even though this is probably more than you wanted to hear, there is a reason that “Big Bottle “ glass sounds like it does, and it has nothing to do with the bottle. Respectfully submitted.......

[shakti]

Dave, thanks for this clarification. I didn't mean to imply that the large glass envelope had anything to do with the sound. But in the world of guitar amps, there's only a few different output tube types in use. So the "big glass" ones (KT66, KT88, 6550) all seem to share some characteristics that make them sound different than, say, EL34s.

You know, it's extremely useful to have someone with your kind of knowledge on the board. The way you talk about tube amp designs, even from a guitar amp point of view, is quite different than most modern-day designers or DIYers. Us late-comers are very attached to the classic designs, whereas you have a much more profound understanding of tube technology, and a much less nostalgic and more utilitarian approach (at least that's how I interpret it), and that is very refreshing!

[Billy Batz]

The 45/100 has more bog DNA to me, regarding the frequencys, the personality of the amp, and it can be much more gainier, if needed, delivering unmistakable bog stuffs which maybe don't appear in my clips.
i'm very excited to hear such good results with the west coast superlead. It'll be my third amp.

From this base, yes anyone has its way to bog, and now we have two ways, spot on, with common things in their architecture. then, i think that the fuzz has to be looked in a different way than off for cleans and on for wild stuffs. i don't think it's as obvious as we could think, that the fuzz may be completely out of the circuit. indeed, the cleans can be obtained even better while the fuzz is in the circuit rather than out. i know it's quite paradoxal.

Ive gone back and forth with bothg types of amps for almost 20 years now. I thought I had a handle on it for sure at times but I still dont know. The fuzz is huge though. If we knew for sure it was on or off at any given time it would be much easier to pin point a sound and like you said, I highly doubt its as simple as on for wild fuzz and off for cleaner. Especially because I dont think the fuzz is ever cranked up for his sound as much as gain. Adrien Ive been playing my 6550 amp and going back and forth between lead and bass components and playing my 45/100 too. Theres always something not quite there.

The 45/100 doesnt have enough breakup to me, the low end is too boomy when I do push it, and it seems to me to be missing the throatiness in the mids. My 6550 lead settings, seem to lack depth but it has the breakup. Going over one by one to bass components seems to help but I know I can never even get close without the 5000p brite cap dialing the volume back like turning up a high pass filter to control the low end. It does feel like the best I can get is somewhere in the middle. lead V1 cathode, lead brite cap, bass everything else. If someone was to say they knew for a fact that fuzz was on the entire time and he just worked the vokume, well that would throw a monkey wrench in everything with a whole extra variable but I almost want that to be the case because otherwise the answer is in non-quantifiables.

Add that 5000p brite cap to a 45/100 and that would definitely improve matters for me with that amp

[shakti]

OK, here's a new video recording, this time trying to showcase the differences between various bright cap and V2 bypass cap combinations. I didn't have time to put any of this on switches, so there's no V1 cathode switching.

I changed my recording approach for this one. First of all, I am just using a cheap Fostex AR-4i recording interface for iPhone. It has just two very small microphones attached, but with an input for an external microphone which I don't yet have. So this is all being recorded by those two tiny microphones. Previously I placed it way back in the room to get more of a room sound and not directly in front of the speakers. But the room is very small and hard sounding, so that actually sounds quite shitty...this time I recorded much closer to the cab, so with the sensitivity set lower. This seems to result in a much cleaner recording with less overload artifacts, and less of the hard, short reverberation of the room. But it's not directly in front of the speaker cone either, and I probably could have found a better spot to record. Still need to learn a lot to make even a half decent recording... Don't expect this to sound very good. And it certainly doesn't sound quite like what I heard in the room. The recording is more muffled and closed-in, the sound was a little more open and breathing in the room. So while this is still in an attempt to sound like BOG, don't expect this recording to be close.

Again, this is the '69 SL clone, but with V1 rewired to shared cathode. 6550s biased at just under 30 mA. G12H cab. '69 CS Strat, Castledine Supra-Vibe with preamp engaged. The output volume of the Castledine was at noon when I started, but was adjusted during the video. Towards the end I switch on an NKT 275 Sunface, and finally a Foxrox Paradox TZF just for fun.

Amp was set with Presence 6, Bass 3, Mids 7, Treble 4, Bright channel volume 7. Daisy-chained onto an unused amp.

Lastly, I am speaking during the video to explain when I am switching in and out the different caps. You'll have to turn it up really loud to hear me, even though the amp was heavily attenuated. I had the amp set at 8 ohm (hence 47k@8ohm NFB), with one output going straight to a 16 ohm Alex Attenuator set at load. This means already -3dB attenuation. The other output via another 16 ohm Alex Attenuator set at the variable setting, which means probably at least *another* -15 db, so this is severely attenuated.
The caps I am testing are the stock WIMA MKA .68uF V2 bypass cap being switched in/out, and on the bright channel volume control I switch in and out two different NOS Radiospares silver mica 1500pF caps. When I measured those after I recorded the demo, they actually measured around 2000pF each, so I am actually testing 2000pF, 4000pF or no bright cap.
Right towards the end of the demo I think one of the leads on one of the 1500pF caps worked itself loose from the hook-on clip I was using, so it may not have been actually switched in, but the difference is very small, especially when I had a fuzz running.

Please let me know what you think of what you hear! I am going to have another go but need to find a better way to record.

[shakti]

The 45/100 has more bog DNA to me, regarding the frequencys, the personality of the amp, and it can be much more gainier, if needed, delivering unmistakable bog stuffs which maybe don't appear in my clips.
i'm very excited to hear such good results with the west coast superlead. It'll be my third amp.

From this base, yes anyone has its way to bog, and now we have two ways, spot on, with common things in their architecture. then, i think that the fuzz has to be looked in a different way than off for cleans and on for wild stuffs. i don't think it's as obvious as we could think, that the fuzz may be completely out of the circuit. indeed, the cleans can be obtained even better while the fuzz is in the circuit rather than out. i know it's quite paradoxal.

Ive gone back and forth with bothg types of amps for almost 20 years now. I thought I had a handle on it for sure at times but I still dont know. The fuzz is huge though. If we knew for sure it was on or off at any given time it would be much easier to pin point a sound and like you said, I highly doubt its as simple as on for wild fuzz and off for cleaner. Especially because I dont think the fuzz is ever cranked up for his sound as much as gain. Adrien Ive been playing my 6550 amp and going back and forth between lead and bass components and playing my 45/100 too. Theres always something not quite there.

The 45/100 doesnt have enough breakup to me, the low end is too boomy when I do push it, and it seems to me to be missing the throatiness in the mids. My 6550 lead settings, seem to lack depth but it has the breakup. Going over one by one to bass components seems to help but I know I can never even get close without the 5000p brite cap dialing the volume back like turning up a high pass filter to control the low end. It does feel like the best I can get is somewhere in the middle. lead V1 cathode, lead brite cap, bass everything else. If someone was to say they knew for a fact that fuzz was on the entire time and he just worked the vokume, well that would throw a monkey wrench in everything with a whole extra variable but I almost want that to be the case because otherwise the answer is in non-quantifiables.

Add that 5000p brite cap to a 45/100 and that would definitely improve matters for me with that amp

BB, you summed up my sentiments very well! Especially the part about treating the volume bright cap as a high pass filter to control the bass. But as I understand it, you seem to prefer a bass tone stack and no V2 bypass cap? Starting with a lead tone stack it's possible to parallell in other caps to arrive at bass values, so that would be an interesting experiment.

I do however feel that a Lead type amp can give the depth and grunt (throatiness?) with the right cab, lots of volume, and the Uni-Vibe preamp.

I agree, it's definitely not as simple as clean = no fuzz and fuzz on = wildness. But if you watch the video you can see some parts where he is clearly switching the fuzz. I've mentioned Stepping Stone before. But this is the key - if you can set your amp up to sound like both the fuzzless *and* the fuzz parts and how both of those parts respond to guitar volume changes, then you have something.

[Billy Batz]

But as I understand it, you seem to prefer a bass tone stack and no V2 bypass cap? Starting with a lead tone stack it's possible to parallell in other caps to arrive at bass values, so that would be an interesting experiment.

Actually I prefer the 330u at V2 but I guess thats not always stock and I shouldve mentioned that. Adds that extra low end push to keep things from being too thin. I have everything in this amp on a switch. At least just bass/lead values. Used to be NFB, sag , B+, everything but I found I always used those switches all the way one way or the other and never changed them so I took them out.

By throatiness I just meant that super sweet low mid range thing happening in BoG. Especially in MG. Univibe makes a huge difference of coarse.

The other part I always thought I had nailed for no fuzz was the intro to Who Knows. Listen very carefuly at the very begining. He starts out and the tone is thin and trebly like a backed off fuzz and bam- volume cuts out then he rolls it up and its like a bass injection. Raw amp. From there I think he just plays around with the wah (which also has a sans fuzz sound to it) and octave.

[daveweyer]

Shakti,
Thanks, I also never meant to imply that it was simply the big bottles which were making a difference in what folks heard coming from the tubes. You basically have seen beam power tubes in big bottles and power pentodes in straight bottles, so the distinction is obvious. As you already know, the only tube types used in the amps you love were pretty much confined to the EL34 or 6CA7 on the one hand, and then all the beam power tubes on the other.
Both types are lovely in my mind and really seem as though they have won a permanent place in the hearts of guitar players world wide. If it weren't for that love, I don't think we would even have tubes today --the HI FI market was just too small to support the manufacture of tubes.
As for the amp designs, well, you are certainly correct to believe that it was the sound of the Fender Bassman which won the hearts of guitar players permanently in this epoch, and that basic design has found its way into practically every product ever made which captured the hearts of electric guitar players on the amp side of things.
I always thought that it didn't HAVE to be just that design which would provide the needed crunch and tone, and my experiments with Jimi's amps (and many other's) went part way to proving that.
So you are also correct to think I may be looking at the amp subject from a little more universal perspective, even though the old RCA designs which Fender used were also the ones I built first, you know back when I was young and actually thought I knew something and could make a better product on my own...........
But if you build enough amps, you get bored, and then start thinking "what if?", mostly along the lines of actually VIOLATING every amp principle in the conventional products.
So Bob Hovland and I have been building amps together for many years; he is the traditionalist, and sticks to what he knows and has proven to himself over the years, building some of the most beautiful EL34 powered amps ever seen by mankind, (look up the Hovland Co. Aurora amp, or the Sapphire amp) while I lean as far toward the unconventional as humanly possible, building some of the wildest, most impractical, and off-the-wall contraptions anyone has ever laid eyes on. Between the two of us, we have a lively and ongoing technical discussion, often involving the breadboarding of test designs just to prove a point in the physics of tubes.
Anyway, I certainly understand the love you have of the 2 pole cathode coupled low feedback power amp used in the Fender Bassman and it's clones and offspring.
I mentioned to George in a letter that Leo Fender told me the reason he used that circuit was because it only took one tube in the power amp gain stage and was a lot cheaper to build-- no other reason given. So was it an accident you ended up loving that sound? Or was it just because that's the sound that was used on so many of the classic rock recordings and performances, and you had to accept it as "authentic"? One thing I am sure of is that the sound of the old Bassman is not going away soon, and nobody is going to rush into using some unconventional circuits or tubes--that is unless Jimi has a second coming and decides to use them.........

I'm surely enjoying the clips and tests. There may be something to the FF theory--I do remember seeing Jimi use his foot to rotate the fuzz knob, and, I made a couple FF units which were always in the circuit, with just the fuzz action being switched on by the button--I know that confuses things even more.

[Xplorer]

The 45/100 has more bog DNA to me, regarding the frequencys, the personality of the amp, and it can be much more gainier, if needed, delivering unmistakable bog stuffs which maybe don't appear in my clips.
i'm very excited to hear such good results with the west coast superlead. It'll be my third amp.

From this base, yes anyone has its way to bog, and now we have two ways, spot on, with common things in their architecture. then, i think that the fuzz has to be looked in a different way than off for cleans and on for wild stuffs. i don't think it's as obvious as we could think, that the fuzz may be completely out of the circuit. indeed, the cleans can be obtained even better while the fuzz is in the circuit rather than out. i know it's quite paradoxal.

Ive gone back and forth with bothg types of amps for almost 20 years now. I thought I had a handle on it for sure at times but I still dont know. The fuzz is huge though. If we knew for sure it was on or off at any given time it would be much easier to pin point a sound and like you said, I highly doubt its as simple as on for wild fuzz and off for cleaner. Especially because I dont think the fuzz is ever cranked up for his sound as much as gain. Adrien Ive been playing my 6550 amp and going back and forth between lead and bass components and playing my 45/100 too. Theres always something not quite there.

The 45/100 doesnt have enough breakup to me, the low end is too boomy when I do push it, and it seems to me to be missing the throatiness in the mids. My 6550 lead settings, seem to lack depth but it has the breakup. Going over one by one to bass components seems to help but I know I can never even get close without the 5000p brite cap dialing the volume back like turning up a high pass filter to control the low end. It does feel like the best I can get is somewhere in the middle. lead V1 cathode, lead brite cap, bass everything else. If someone was to say they knew for a fact that fuzz was on the entire time and he just worked the vokume, well that would throw a monkey wrench in everything with a whole extra variable but I almost want that to be the case because otherwise the answer is in non-quantifiables.

Add that 5000p brite cap to a 45/100 and that would definitely improve matters for me with that amp

Dan, Thorleif, i understand what you're facing, and it bugged me too off course, but it seems so clear to me now, even if it'll perhaps evolve, and i'll maybe change my mind, who knows.

i first built a superlead 69, because i thought it was it, for bog. then i understood it wasn't.
i then built a 45/100, and the DNA was there, but something was missing, as you said.
Anyway, once you've got the DNA ( i think you call it the big glass tone. well ... these high non trebly notes on who knows, very specific to bog ) , you can think more clearly ( in my present hypothesis ) about the break up, dynamics, and wild tones.
where is it coming from .... from the amp alone ? or maybe ....... from the amp being pushed ? ....
Dave just said it just before and i think it deserves a lot of focus.

it all made sense to me when Dave talked about the way Jimi's fuzz were set, used for sustain, with volume up and fuzz down. i encourage you to do so.

for the cleans, even if you can get close with no fuzz pedal at all, it's still not fully there, it'll be more obvious if you try a Dunlop blue fuzz ( not a germanium or some others, THIS BC108c one is good as a start ) , because then, you'll get the cleans, the break ups, and the right coloration. still transparent, to the point that you may think it's only all about the amp only.

The other part I always thought I had nailed for no fuzz was the intro to Who Knows. Listen very carefuly at the very begining. He starts out and the tone is thin and trebly like a backed off fuzz and bam- volume cuts out then he rolls it up and its like a bass injection. Raw amp. From there I think he just plays around with the wah (which also has a sans fuzz sound to it) and octave.

i see what you mean. it's indeed very close ! With the fuzz Volume at max , and playing with the strat volume and the input bias of the fuzz ( to potentialy let the wah breath ) , it's even closer ! and you'd think it's the amp alone.

Now, still according to what made sense when Dave said this : then how do you get the wild tones ?
the simple trick to absolutely try, and which would solve the equation, earwise, visualy, and historicaly ( since Dave did this mod on a few fuzz ) , is that the switch may be used to simply engage another fuzz level or stage or input bias value, well anything pushing it even harder, also giving endless notes while staying quite transparent. Well , this, instead of simply switching the whole fuzz pedal ON.

so this helps a lot to fully achieve the break up noticeable on who knows ( the "clean" tones ) , once you have the right DNA first. it also affects the basses, the throaty tone,well, everything .... did you already try ? maybe it didn't work for you ? that's possible. with some of my other fuzz, it didn't work well at all.

Now, the univibe preamp ( at max volume it's even better ) interacting with THIS fuzz/amp setup gives even more of this effect you're looking for.
i see that you're mainly looking for the break up directly into the amp, that's one way, why not. i don't look into it much anymore, it's almost too complicate to be a solution when you see things globaly, when you think of the components value changes you have to do to make it right, the coloration that you're missing, etc ... it all may very possibly be more simple than that.

then, for the second part, the wild tones , there are several ways to get more out of a fuzz, and i hope that we'll work on it.

this way, if you have the right DNA with the amp + the simple modded fuzz + the univibe, you can have the clean/break up , and the wild tones. easy. the best part is that it doesn't contradict anything you see or hear in lives. it's like a magic puzzle piece long missing. please try, i'm sure you can get cool results.
the usual on/off switch is fooling us i think. i don't believe it anymore.

i'd love to work more on this fuzz theory, and on the second wild level, both on the 45/100 and on the west coast superlead., which sounds like it has more of the right DNA than before, especialy in the last clip from bill bockey. but not totaly there like the 45/100 to my ears.
there were three amps at the Fillmore anyway, i certainly don't think they were three 45/100 for sure.
i hear in your clips some things that count into the bog tone. i also hear the 45/100 and this unusual but simple setup, historicaly possible according to what Dave said.
So ... why not one 45/100 mic'ed, and two west coast superleads. the mix featuring the mic'd amp and the theater.
>>>>>>>>>>>>>>>> The Bog tone