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HamishBoxer 25th May 2020 11:07 am

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

fetteler 25th May 2020 12:26 pm

Re: Marshall Amps
 
Let's rock!!!!!

Steve.

stevehertz 25th May 2020 1:19 pm

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%.

Sinewave 25th May 2020 3:13 pm

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.

M0FYA Andy 25th May 2020 4:36 pm

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

Andy

stevehertz 25th May 2020 6:16 pm

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

TowerRadio 25th May 2020 9:26 pm

Re: Marshall Amps
 
Elstone transformers in the prototype.(and maybe a Gov. surplus choke).Les

ITAM805 25th May 2020 10:21 pm

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-)

mark_in_manc 26th May 2020 11:56 am

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 :)

stevehertz 26th May 2020 12:06 pm

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.

mark_in_manc 26th May 2020 10:23 pm

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 :)).

stevehertz 27th May 2020 9:20 am

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!

retailer 27th May 2020 11:44 am

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.

ms660 27th May 2020 12:20 pm

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.

Radio Wrangler 27th May 2020 12:32 pm

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

mark_in_manc 27th May 2020 12:38 pm

Re: Marshall Amps
 
Quote:

Originally Posted by stevehertz (Post 1252615)
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!

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

ms660 27th May 2020 12:40 pm

Re: Marshall Amps
 
Quote:

Originally Posted by Radio Wrangler (Post 1252694)
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

You just need a Green Bullet into the amp.

Lawrence.

McMurdo 27th May 2020 1:52 pm

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:

ITAM805 27th May 2020 2:02 pm

Re: Marshall Amps
 
Quote:

You just need a Green Bullet into the amp.
I think David might mean a harp as in the heavenly choir instrument rather than a gob iron ?

ms660 27th May 2020 2:14 pm

Re: Marshall Amps
 
You mean one of those big classical pluckie things:)

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

Lawrence.


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