|
Websites Found an interesting website? Post the details here and share it with the rest of us. Please stick to websites that are in some way related to our hobby/interest. |
|
Thread Tools |
27th May 2020, 3:20 pm | #21 |
Dekatron
Join Date: Jun 2009
Location: Staffordshire Moorlands, UK.
Posts: 5,273
|
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.
__________________
Kevin |
27th May 2020, 3:41 pm | #22 |
Dekatron
Join Date: Sep 2011
Location: Rugeley, Staffordshire, UK.
Posts: 8,832
|
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.
__________________
A digital radio is the latest thing, but a vintage wireless is forever.. |
27th May 2020, 4:25 pm | #23 |
Octode
Join Date: Jan 2012
Location: Wimbledon, London, UK.
Posts: 1,465
|
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. |
27th May 2020, 5:32 pm | #24 | |
Octode
Join Date: Jan 2012
Location: Wimbledon, London, UK.
Posts: 1,465
|
Re: Marshall Amps
Quote:
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. |
|
27th May 2020, 5:42 pm | #25 |
Octode
Join Date: Jan 2012
Location: Wimbledon, London, UK.
Posts: 1,465
|
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. |
27th May 2020, 6:20 pm | #26 |
Dekatron
Join Date: Jun 2009
Location: Staffordshire Moorlands, UK.
Posts: 5,273
|
Re: Marshall Amps
I dated it as it's written on it, and it was inspected by Carole
__________________
Kevin |
27th May 2020, 6:47 pm | #27 |
Dekatron
Join Date: Sep 2011
Location: Rugeley, Staffordshire, UK.
Posts: 8,832
|
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.
__________________
A digital radio is the latest thing, but a vintage wireless is forever.. |
28th May 2020, 4:58 pm | #28 |
Pentode
Join Date: Oct 2018
Location: Coventry, West Midlands, UK.
Posts: 220
|
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.
|
28th May 2020, 6:55 pm | #29 | |
Octode
Join Date: Jan 2012
Location: Wimbledon, London, UK.
Posts: 1,465
|
Re: Marshall Amps
Quote:
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. |
|
28th May 2020, 11:41 pm | #30 |
Hexode
Join Date: Sep 2004
Location: Newcastle upon Tyne, Tyne & Wear, UK.
Posts: 475
|
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.
|
29th May 2020, 9:37 am | #31 | |
Octode
Join Date: Jan 2012
Location: Wimbledon, London, UK.
Posts: 1,465
|
Re: Marshall Amps
Quote:
Colin. |
|
29th May 2020, 10:00 am | #32 | ||
Dekatron
Join Date: Sep 2011
Location: Rugeley, Staffordshire, UK.
Posts: 8,832
|
Re: Marshall Amps
Quote:
__________________
A digital radio is the latest thing, but a vintage wireless is forever.. |
||
29th May 2020, 11:22 am | #33 |
Hexode
Join Date: Nov 2010
Location: Sheffield, South Yorkshire, UK.
Posts: 278
|
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. |
29th May 2020, 3:10 pm | #34 | |||
Octode
Join Date: Jan 2012
Location: Wimbledon, London, UK.
Posts: 1,465
|
Re: Marshall Amps
Quote:
Colin. |
|||
29th May 2020, 4:01 pm | #35 |
Pentode
Join Date: Oct 2018
Location: Coventry, West Midlands, UK.
Posts: 220
|
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.
|
29th May 2020, 4:36 pm | #36 | |
Nonode
Join Date: Aug 2015
Location: Cambridge, Cambs. UK.
Posts: 2,198
|
Re: Marshall Amps
Quote:
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
__________________
BVWS Member |
|
29th May 2020, 5:10 pm | #37 | |
Pentode
Join Date: Oct 2018
Location: Coventry, West Midlands, UK.
Posts: 220
|
Re: Marshall Amps
Quote:
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! |
|
29th May 2020, 5:14 pm | #38 | |
Dekatron
Join Date: Sep 2011
Location: Rugeley, Staffordshire, UK.
Posts: 8,832
|
Re: Marshall Amps
Quote:
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.
__________________
A digital radio is the latest thing, but a vintage wireless is forever.. |
|
29th May 2020, 7:04 pm | #39 | |
Nonode
Join Date: Jul 2010
Location: Folkestone, Kent, UK.
Posts: 2,172
|
Re: Marshall Amps
Quote:
|
|
29th May 2020, 8:18 pm | #40 | ||
Nonode
Join Date: Aug 2015
Location: Cambridge, Cambs. UK.
Posts: 2,198
|
Re: Marshall Amps
Quote:
Martin
__________________
BVWS Member |
||