The 'Marshall' Sound

[David Schwab]

I think the caps they use are key to the tone. The tone stack is a fender bassman rip off many times. Or straight out of tube manual example circuits back when they were pushing glass.
...Those old Marshall transformers were buff and did a thing that also makes them unique..

I've read a bunch of times that Jim Marshal started out by hot rodding Fender Bassman amps, and then just started making his own amps based on that mod.

Those output trannies were a big part in the sound.

Funny how Leo got his basic design from the RCA tube manuals, and then others (like Mesa and Marshal... even Alembic) got their start modding Fenders! There's some kind of poetry there.

[bob p]

here we go again. i've looked at a bunch of old RCA tube manuals, and I've never been able to find famous Fender circuits in them. am i just looking in the wrong ones? help me, please!

[Chadwick]

a worthy search

Did someone mention Western Electric? Are there some sources there to look into?

Its agreed that Marshall stole the bassman right?

My initial 'lore' was refering to the tone stack specifically and I still think we might find the 'father' of the fender tone stack in a tube radio somewhere. At least the princeton tone control, though again I can't prove it in court and I'm not trying to start more 'lore'.

Just based on the RCA manual we can agree that Leo didn't invent the way to hook up a gain stage right? Is that safe to say based on the data and gain charts? So all we are left with is the tone stack and maybe some values.

Here is page 56 from R-10 RCA tube manual.. Wrong tube but we can at least put to rest that LEO invented the cathode resistor and bypass cap. I'm sure there is more, i just scrolled to that page randomly. I'm sure they gave away some values and Leo probably ran with it. It won't be a complete scheme from input jack to output transformer, but it will be values and hook up instructions spread out through the manuals...

I'm very interested to actually find the RCA tube manual or WE or whoevers data sheet on the 12ax7 equivalent, or 6v6 though there is at least a couple decades of tubes that had no system for the part numbers that we could possibly track. We might then be able to attribute certain values to the manufacturer or Leo.

[David Schwab]

Its agreed that Marshall stole the bassman right?

Yeah, but it's lot like Leo had any kind of copywrite or patent on it... And the original Boogie was a Princeton!

Just based on the RCA manual we can agree that Leo didn't invent the way to hook up a gain stage right?

There is a lot of lore around Leo Fender... one is that he was an electronics engineer. He was actually a machinist by trade. He designed and built all the big machines Fender used. He was a very clever guy for sure, but he really did something because it was easy to manufacture (which is a smart thing to do)... the bolt on neck for instance. He thought like a machinist... "how can this part be made using machines?" He picked parts and wood because they were available and inexpensive (like alder). The bent steel bridge plates. He used a punch to make pickup flatwork. He machines the maple necks to include the fingerboard so he could eliminate that whole step of gluing on a fingerboard (until he didn't like the way they looked when they got worn!). Many innovations in guitar construction. And they were all radically different from "real" guitar makers like Gibson. Look how the Les Paul looked like a small arch top. Leo had the "slab" body Tele. I'm sure Gibson thought they were a joke! But he created a whole new sound.

So he had a radio repair shop, as that was a hobby of his, and he started fixing guitar amps... the rest is history! He surly did invent some stuff, and has patents on those. Jim Marshal started doing what Leo did... repair amps and mod them. I guess it's an evolutionary thing.

One thing Leo is purported to having done was reject some of the first speakers he got because he felt they were too clean. So he had some idea of what sound musicians wanted, obviously by having them as customers, since he never learned to play himself.

I bet most of the early tube amps were pretty much "text book" circuit designs. Boy I love the histories of all these companies!

[hasserl]

i don't think that the marshall sound comes from the tone stack. it comes from a class A triode driving a cathode follower, and driving THAT circuit into the tonestack. IMHO THAT is the essense of the famous "Marshall" sound.

I've had some luck with a plate driven TS (Bax type at that) in an amp giving a decent Marshall style tone. ANd I believe Roccaforte amps use a plate drive TS, and they definitely have a VERY Marshallish tone. I'm not convinced the cf driven tone stack is the essence of that sound.

[dai h.]

from what I recall Jim Marshall was converting hi-fi amps into bass amps (Leak??) and importing Fenders which was expensive (and apparently American amps are still expensive in the UK), and at some point Ken Bran or somebody suggested that, "why didn't they build their own?", then they copied the 5F6-A but used local transformers, speakers, plus the local version 6L6 type (KT66--they first used the same 5881), and off they went...

re: the Western Electric connection, maybe it was the tone stack that was licensed or something like that?

re: cathode vs. plate follower tone stack: supposedly the Park Rock head (plate follower TS) still sounded Marshally according to someone who had/used one.