Marshall Amps
 

http://www.dudleycraven.com/ The man who built them.

Re: Marshall Amps
 

Let's rock!!!!!

Steve.

Re: Marshall Amps
 

I have been playing guitar for over 50 years and during that time have owned and/or played a great many valve amps including high cost, esoteric models by Mesa Boogie, Hughes & Kettner, Fender and so on. In fact I'm led to believe that I was the first non-celebrity owner of a Boogie amp back in '78. Given all that, my favourite amp is a Marshall. I love the Marshall sound and I just wanted to make that clear. I've also read a GREAT deal about Marshall amps and I have been invited to Marshal by their chief designer (who became a personal friend) to try out amps on the famous Marshall stage. Saying that, I feel that a lot of what is written about 'the Marshall sound' is often sparse with the truth.

Basically, Ken Bran and Jim Marshall got hold of a Fender Bassman model 5F6-A amp and - as much as they could given UK parts availability - copied it. That much is well documented too. On that issue of components and component availability, and reading what Jim and Ken both said about them, it's fairly certain that nothing in the first Marshalls was chosen for any other reason than availability and what could be assembled totally by hand in a tiny workroom in the back of a music shop. They are not factory-built amps. So, the amps did sound different from the Fender ones they copied for that reason. The really big difference is the OT, and its ratios - designed for driving a 16-ohm load not 2-ohm. I suspect this was by accident (what was available) rather than design, because the values of the negative feedback resistors are the same, which suggests to me that Marshall (ie Ken Bran, the engineer) were not aware this would make a difference, since otherwise you would think that having nearly three times the negative feedback would be considered a problem... but the result is a great-sounding amp which is somewhat different from the Bassman, of course. And the valves, speakers and cabinet contribute to that too.

To say that the 'Marshall sound' was created by Dudley Craven at home, in his garden shed to me is more than a little misleading. Like I say, I love the Marshall sound, however it was created.

Note: some of the above wording I have lifted from other peoples' quotes on the internet but with which I align 100%.

Re: Marshall Amps
 

I love Marshall amps. Currently have a JCM 900 Dual Reverb 100w head(original, not reissue), JCM 900 SLX 100w head, TSL2000 100w head, 1936 speaker cabinet, did have a 1960A but sold it on. Also have a DSL201 20w combo.

Re: Marshall Amps
 

I recall from the excellent BBC TV programme a while back that the early Marshall amplifiers used mainly Radiospares components.

Andy

Re: Marshall Amps
 

That's true Andy. And vintage amp aficionados pay a fortune for the RS trannies that were used in the first JTM45s. Even RS catalogues from the early 60s era fetch good money as guys like to check out and ID the components used in Marshall amps. There's a whole world out there of 'home brewed' JTM45 amps, fuelled by guys producing trannies, cabinets, control plates fittings, etc etc. In fact I am in the process of building a '63/64 version myself. The cabinet is being made in the US.

Here's an example:http://www.merrenaudio.com/marshall_output_transformers

Re: Marshall Amps
 

Elstone transformers in the prototype.(and maybe a Gov. surplus choke).Les

Re: Marshall Amps
 

Somewhere on this forum is thread about a 1965/6 Marshall Super PA100 that I was asked to service, it had the serial #001. It had two RS o/p transformers, which alerted me that it was something special. Apparently Bran and Craven couldn't at the time, source a single tx that could handle 100W, so they used two JTM45 trannies in series.

The owner didn't even know what he had till I advised him. Marshall invited us up to look at it. They said that Jim Marshall would have made the chassis himself, it was made of aluminium but they soon found that they would easily fracture so thereafter switched to using steel. Surprisingly Marshall didn't make an offer on it considering it apparently being the earliest incarnation of that model, however word got round it later sold for lots of money 8-)

Re: Marshall Amps
 

I had a 70s 100W master volume combo in a 2x12 cabinet. It was awful - weighed a ton, and was really loud by the time it sounded interesting, which meant either loud and really clean, or loud and really fuzzy (full Iron Maiden!), with nothing in between.

Now I have a 'valvestate' 100W thing which someone gave me, as apparently no-one likes them. It's great - really flexible, good-when-slightly-crunchy, and good quiet as well as noisy. It came with a Yugoslav ECC83 which I replaced with a Mullard (cos I had some) to predictably no result whatsoever. I ought to sell that valve and buy a few sets of strings :)

Re: Marshall Amps
 

Not sure how much effect the rest of the valvestate circuitry is having wrt the sound of the ECC83, but from the time I did my very first test of swapping the crappy Chinese ECC83s in a Boogie V-twin rack unit for Mullards, the difference was literally night and day, unbelievable. What was gritty, harsh, discordant distortion was now sweet, harmonically rich and quite simply, nice on the ear.

Like I say, the ECC83 in the valvestate may, to some extent, be paying lip service to the valvestate sound, or it may simply be a decent ECC83 already in there. But yes, when you hear the difference, it's there in buckets, I've done it loads of times.

Re: Marshall Amps
 

Oh, that's really interesting. Right, I'll pull the chassis out and find some ECC83s tomorrow, and get the kids to help me do a blind test. (It's OK, they're old enough that this is not abusive and/or dangerous:)). Any suggestion for doing it clean / bit crunchy / really fuzzy?

(Full disclosure - I'm a terrible inverted snob, and I'll be sad if I can hear a difference - as I was when I could tell a difference and even express a preference between cheap Whisk(e)y and something pricey! But I promise to be true to science :)).

Re: Marshall Amps
 

Play an open E or G chord and try different levels of distortion from 'cusp of' to 'very'. like I say, they may not be using the ECC83 to have a major effect on distortion. It might be there more for the mind than the ears!

Re: Marshall Amps
 

My guitarist son and I did some comparison listening tests with various 12AX7's, we used a locally made amp called Woogie from local music store I believe it was a copy of a JCM800, we swapped only the first preamp valve. The valves we had were all new old stock - Mullard, Australian made Philips Miniwatt, Brimar, RCA, Sovtek and a brand called Ciftie which I think may be French .
I could not pick any difference but that is not surprising I'm not a guitarist, guitarists are a strange breed, my son said there was a difference in the sound, it was not night and day though, they all sounded good, but he thought the Brimar might have sounded the nicest.

Re: Marshall Amps
 

Guitar amplifiers tend to be wound up loud, valve electrodes rattle which in turn can modulate the electron stream, not all makes of valves are constructed the same.

It's what hits your ears and other bits that counts, by whatever means.

The Fender Bassman that was mentioned earlier, it's also a popular choice for the harp player.

Lawrence.

Re: Marshall Amps
 

You've now got me wondering what a harp would sound like with a serious fuzz pedal and a lot of crunchy watts rather like Jon Lord did to his hammond especially the intro to 'Lazy"

David

Re: Marshall Amps
 

Well, I think it's probably in the signal chain, since it takes a while to warm up...but that might be a simulation ;D

Re: Marshall Amps
 

You just need a Green Bullet into the amp.

Lawrence.

Re: Marshall Amps
 

I've found alot of modern ECC83's rather microphonic. Whether this is a problem or not depends on the model of amplifier, where the valve is mounted, the gain of the circuit, etc. The guitar amp valve specialist retailers can supply microphony-tested valves to order. A mullard pre-amp valve is going the way of a certain other sought-after audio valve, with the colour of the ink and the batch code determining how many 20-pound notes extra you'll have to cough-up. :dunce:

Re: Marshall Amps
 

I think David might mean a harp as in the heavenly choir instrument rather than a gob iron ?

Re: Marshall Amps
 

You mean one of those big classical pluckie things:)

I was meaning a blues harp such as marine band etc.

Lawrence.

Re: Marshall Amps
 

In case anyone's wondering what all the fuss is about, here's a nice original one that arrived this week with me, dating from the mid 1970's.

All the transformers are made by Dagnall.

Re: Marshall Amps
 

When comparing different (for example) ECC83 valves in a guitar amp, you only really notice the difference when the amp is being driven into distortion, the clean sounds will sound similar. Also, if you're comparing a load of different modern valves, then they may well sound similar. The strong point I'm making is, a modern 'Chinese' valve just will not hold up to a Mullard when overdriven. See my earlier descriptions.

Re: Marshall Amps
 

If people are still puzzled as to what "harp" is being talked about, the blues harp is actually a harmonica/mouth-organ and Marine Band relates to a set of seven pitched in different keys. I think Marine Band was an early and very good manufacturer of these sets.

I think I have a soft-bound copy of a publication on the history of Marshall amplification, but I can't locate it at present. It may have been co-written by Ken Bran and someone else and had no mention of anyone called Dudley Craven. Jim Marshall was a drummer and owned a music-shop. I think Ken Bran was working full-time somewhere else before the event of copying the Fender Bassman 5F6-A came about. To suggest that Ken Bran was only there to populate the tag-boards is, I think, a bit of an insult. After all, when Jim Marshall got into a bad business deal later on and couldn't sell amps bearing his own name, he got Ken to make copies which were called "Narb". That's Bran backwards, get it? Certainly not "Nevarc".

Just my tuppence-worth, Colin.

Re: Marshall Amps
 

Kevin,
The rust does suggest 1970-something, but I think that circuit board doesn't. The early amps would have had tag-strips or turret-boards. Has someone been doing some "improvements" to yours?
Colin.

Re: Marshall Amps
 

I still haven't found my copy of the book I mentioned, but I have found a reference to it on the web:

https://books.google.co.uk/books?id=...page&q&f=false

It is called "The History of Marshall: The Illustrated Story of "The Sound of Rock" and was written by Michael Doyle. On page 12, there is a reference that I hadn't really noticed before, of "Ken and his long-time friend and assistant Dudley Craven".

I really must locate this book amongst my others.....

Colin.

Re: Marshall Amps
 

I dated it as it's written on it, and it was inspected by Carole ;D

Re: Marshall Amps
 

Here are the two books that I have about Marshall amps. The story (relatively short as it is) about how the amp was 'developed' is on page 39 of 'The The father of Loud' book.

Re: Marshall Amps
 

Marshall changed to PCB's in 1973, prior to that they would have been turret boards. As far as I know no Marshall amps were ever built with tag strips.

Re: Marshall Amps
 

I stand corrected. My mistake was in assuming that when McMurdo described his amp as "original", that he meant one of the early ones, which were of course built in the early 1960s. I should have checked the decades.

With regard to my mention of tag-strips, I really meant tag-boards similar to those used in Vox guitar amps and recalled that Barbara Craven claimed that Ken Bran populated "the component tag boards", even though he was Jim Marshall's Chief Service Engineer.

My excuse is that I was tired, which is a better one than some that I have heard recently.

Colin.

Re: Marshall Amps
 

Here are some pictures of an early Super Lead Plexi 100w I once owned. The amplifier components are mounted on a turret board and the power supply caps on a (thick) matrix board. The electrolytic caps are 32uF RS Components and there is an RS bridge rectifier mounted on the end of the chassis.

Re: Marshall Amps
 

Yes, turret-board. I notice that your amp has those knobs that looked nice in the clear light of day, but were just about impossible to work out where they were set on a dark stage. I've been there and done that myself on a home-brew guitar amp :shrug:.
Colin.

Re: Marshall Amps
 

"Those knobs" are what are used on current Marshall amps and have been for decades now - as you know Colin, I'm sure. But anyway, aren't Marshall users supposed to turn everything up to 11?

Re: Marshall Amps
 

Dave Simpson guitar on youtube has an interesting video on why he prefers transistor amps, worth a look, great guitarist as well, really infectious watching,
Regards, Alan.

Re: Marshall Amps
 

I haven't worked on a lot of Marshall amps, but I was sure that there were some that had the early metal nameplates with the red lettering and had bigger knobs with rather more obvious index lines. I understand that those small knobs are typical of Marshall, but I would have thought that once people saw that the other knobs were more convenient, Marshall would have at least used them on some of the later amps, but maybe not the "re-issue" models. Perhaps by then all the performers had fried their brains with the loudness and didn't really care where the knobs were adjusted to.
Colin.

Re: Marshall Amps
 

The very early JTM45's did have a different type of control knob but these were only produced for a very short period (1963-1965 I think). Pretty much every Marshall amp produced since then has used the current style of knob.

Re: Marshall Amps
 

Fortunately, audio is much easier than whisky flavour because it's measurable.

Time I think to get the scope on to a Marshall and find out something about its gain structure. For example, as volume is increased, one would expect the output stage to overload first. Overload behaviour of different EL34 samples may well be different, accounting for some of the audible differences.

But we then have to look at the earlier stages to account for sensitivity to different sample of ECC83.

As a start, a relevant question is: once the output stage is clipping, at what volume point does an ECC83 section also begin to clip? If the 'magic' ECC83 isn't clipping, it's difficult to understand the reported variation between samples.

On the other hand, maybe an ECC83 operating in normal linear mode is at some volume point being asked to drive grid current into a clipping EL34. Again, different samples may exhibit different behaviour. Either way, I suspect that we're looking at valve characteristics outside the normal data sheet parameters and it would be interesting to know the relevant drive conditions.

Then we could begin an actual technical discussion on the 'Mullard magic'.

It's what we normally do with 'magic'!

Martin

Re: Marshall Amps
 

Hmmm, try telling some of the cork sniffing "tube rollers" that... They will assure you their ears are far more sensitive than any oscilloscope and they can hear things that can't be measured! :)

The gain structure will depend a lot on which Marshall amp you are looking at. Older versions with no master volume control will behave a lot like you describe with power amp distortion starting first but a lot of the more recent models will have higher gain preamp stages with most of the distortion coming from the preamp valves. A word of advice if you are going to start driving a non master volume Marshall into distortion I would recommend getting some good ear defenders! Once you turn that volume knob much above about 2 they start to get pretty loud pretty quickly!

Re: Marshall Amps
 

There were in fact four if not five different styles of knobs used on Marshall amps - see photos. My current build project that I referred to earlier is a 64 style amp. I made one about 15 years ago, and you can see the metal 'coffin' logo on the photo attached. Called a coffin logo because that's exactly what they are made out of, a coffin nameplate. My new build will be much more accurate than the photo you see, that one has long gone.

Re the photo with text, where it refers to "the bottom photo", due to the way I've cropped images, it is the photo above that text itself.

Re: Marshall Amps
 

Quite so, in the early 80's I had a 1968 100W plexi, I started noticing the audience wincing at my kerangs - was my playing that bad, no I was told "it's so ******* loud" :o

Re: Marshall Amps
 

So.....the Marshall pre-amp is also a volume limiter. The overload characteristic of the ECC83 is all important to the sound of the end result. Unexplored audio territory I guess.

Martin

Re: Marshall Amps
 

I have an old 100W Marshall JMP, well old-ish I suppose. It's a 1969/1970, the first year of the metal face plates after the plexi glass face plates.

I bought this amp back in the 90's for £70.

LOUD!!!

I also met Jim twice too, when he used to have the Marshall road show that toured around the country in the late 80's to demonstrate the new products. Thats one of my true 'claim to fame' stories. :)

Re: Marshall Amps
 

(Just a little side note mods)

Hi David,

I have read somewhere in the past that many harp/harmonica players liked the sound they got when using a valve amp with a very un-balanced phase inverter valve installed that created a more a-symmetrical wave form that resulted in a more distorted type of sound. Something like that I think.

Would that be about right David ?

Re: Marshall Amps
 

I don't know about that, and I doubt many musos would that that was the case so long as they got the sound they wanted. What I do know is, it's quite normal for harmonica players to mic up their instrument into a small, 'practise' valve amp turned up full, and then mic that up into the PA. That way they can easily overload the practise amp with it being too loud.

Re: Marshall Amps
 

It would be possible to make a variable unbalancer... particularly for amplifiers with cathode-coupled (long tailed pair) phase splitters.

David

Re: Marshall Amps
 

Yes, the great John Lord. I couldn't believe it when I heard he had died:'(

A local(ish) lad from Leicester, I believe, formally of Deep Purple and before that the Flower Pot Men, which morphed from the Ivy League, a member of which died in poverty in a Lincoln flat close to where I used to work.

As regards to guitar players, I recently discovered this young lady on 'youtube', not just talented, but gifted in her style of playing in my opinion. After seeing her play she'll just make you want to give up and never play again - what's the point after seeing this - could you ever be this good:-
https://www.youtube.com/watch?v=rEr2JZOa27c

Re: Marshall Amps
 

(Sorry mods :))

Nice one Techman, brilliant.

& don't forget about Tina S either playing some Beethoven.

Well, lets face it, if wasn't for Marshall amplifiers, the sound of the electric guitar would be as far back as the Generals ! :-)

https://www.youtube.com/watch?v=o6rBK0BqL2w

:)

Re: Marshall Amps
 

Long-tailed pair phase-splitters are sometimes intentionally "unbalanced" in terms of the anode resistors not being the same, simply in order to balance the outputs of the two triodes in the long-tailed pair. If the anode resistors are identical, the outputs of the two triodes will differ.

So, if you built a long-tailed pair phase-splitter with adjustable anode resistor(s), you might achieve a (maybe limited) unbalance. You could get even cleverer by having the two anode resistors as a dual pot, with one increasing as the other decreased its resistance. I would imagine that the amount of unbalance and difference between the anode resistors would have to be limited, but perhaps someone with more knowledge of valve circuitry might have some better ideas?

Colin.

Re: Marshall Amps
 

Ok, she is better than me and nifty on the fretboard, but she isn't the only one. I tend to think positively about better players than myself - the "why can't I do that? I'll give it a bash".

Why hasn't she been recorded? Or maybe she has, but in these days of downloading music, I just haven't noticed.

Other impressive players in the "shred" zone include Joe Satriani, Steve Vai and Eddie Van Halen. If you want to be truly dumbfounded to the extent of giving up playing, just take a look at what Jeff Beck can do (I have a go at some of his stuff, too. He is getting on a bit but can still pull it out).

Colin.

Re: Marshall Amps
 

Thanks for the link Techman, there seems to be no end of talent available on Youtube from kids of all ages, it just blows me away!

These talents represent one of the more positive aspects of Youtube. Many artists would surely remain hidden otherwise.

Re: Marshall Amps
 

I watched the video, gotta say....zzzzzzzzz.

Each to their own.

I'm old enough to remember Sister Rosetta Tharpe on telly near Manchester, go babe go:

https://www.youtube.com/watch?v=Y9a49oFalZE

Lawrence.