Evolution of the 100 watt superlead circuit

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Ned B
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Evolution of the 100w SL circuit

Post by Ned B » Sat Feb 05, 2005 12:29 am

Great group of individuals here interested in the details of Marshall. I have gathered some observations over the years of aquiring and playing vintage Marshalls, mostly 100 watters. I'm finding Mr. G's post interesting since it draws on info from reliable sources. But it seems strange to me that steel chassis amps would come in that late because there would have been so many evolutionary changes and a hugely increased production within a very short span.

While Marshall has not been great with record keeping, Drake on the other hand is pretty good. Their stock numbers ink stamped on the bells represent models made specifically for Marshall. Each one of these exist in their database with inception production dates. My time time based on their info makes sense to me, so here's what I have to throw into the discussion for friendly debate:

The 1202-84 OT, Drake's first for the Marshall 100w came out 11/65 replacing the dual OTs. 05/66 is when the 1204-43 PT came out replacing the potted RS (likely made by Woden) PT. 02/67 marks the intro of the 1203-80 and 1202-119. I have seen photos of what I believe to be one of the first to have those and it had the JTM45 front panel, gold SL back panel with window serial number and aluminum chassis. I think by 03/67 the switch to the "black flag" panel with steel chassis had been made followed shortly by the JMP panels and even some "polarity" panels. The 1202-132 came in 06/67. At this stage I have seen the start of the PI cap on top with the 2 100mfs and 2 32s inside. Based on the flow of changes, Dagnalls probably started appearing very late in '67, but '68 owns the bulk of those Dagnall 100s with one cap on top. Then there are some with two on top when they moved the preamp filter next to the choke followed soon by six on top with the rotated OT. I believe the metal panels started May/June of '69.

This seems a resonable timeline to me.

I'm preety sure the "Orbison" catalogue is early '68 and the white stack one is '69 because their accompanying price lists are dated. There was one early catalogue that I know of that was not shown in Doyle's HOM book and that was "Go Over Big With Marshall" from '67 whish shows the only catalogue shot of an early strap handle stack with tall bottom.

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Post by Guest » Sat Feb 05, 2005 9:08 pm

I'm in total agreement with Ned's layout of the timeline. I've spoken with Ned via e-mails and on other bbs for many years and he knows his stuff. BTW Ned, is your "black flag" 100 watt (SL/10074) a steel chassis amp? Also, is the amp your refering too as "one of the first with the 1203-80 & 1202-119 trannys" the SL/10007 amp? On the subject of catalogs; Ned; do you have the one that is missing from the Doyle book? Doyle makes reference the early 1967 catalog as having a black and yellow scheme to it I believe.

Also, in a previous post myself and "Guest#1" (I guess I'm "guest#2) spoke about the yellow/tan colored resistors not really showing up in aluminum chassis amps that often, well I did notice that some Park amps with aluminum chassis used these resistors in greater numbers. In all fairness, Parks were assembled using spare parts which probably why we see the combo.

And in conclusion I'd like to appolgize to George for sending his thread into a tail spin. :D

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Post by Ned B » Sat Feb 05, 2005 11:54 pm

I rember the tan resistors being 470K mixers, a feature late in the Drake period. Here's the link to that interesting and mint transitional amp # 10007. http://www.xs4all.nl/~aukhammy/marshall/. My 10074 has a steel chassis. I know of a black with a serial number of 10298. The boxes for the early steel chassis 100s had the shorter rails that the back panel screwed onto based on the block end aluminum chassis sliding underneath.

I mis-quoted the title of that '67 catalogue. Is was titled "Get With the Marshall Sound" which was yellow, white and black with someone playing a Ric bass on the cover. The "Procedure Booklet" has the same cover in black with a white background. I've got those in my posession. I wish I had the ealier four.

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Post by mightymike » Mon Feb 07, 2005 9:42 am

Velvet George wrote,
Very late '67 to early '68. The 12000 series plexis. Named for the serial #'s in the 12xxx range. EVH's famous amp is from this era.

Now we see the first split cathodes using a 820/.68uf combination. Normally with a 820/.68uf in V2 as well. The Tone stack changes to the 33k/500pf arrangement. 47k NF. .022uf PI caps. .0022uf cap in the bright channel V1.
George ,

I was wondering if you or some knowledgeable person could clear a few things up concerning the different era board layouts. I'm looking at the Board layouts for 68, and 69 on the Ref CD. (I Know it's a work in progress.) I'm comparing them to the above quote and what you sent me. I'm not very good with tube amp jargon so bear with me:

Here's a link to the board layouts on that CD.
http://uploads.bestupload.com/redir/2454.gif
Image


1) When you said, "The Tone stack changes to the 33k/500pf arrangement>" Are you talking changing the 56k/250pf arrangement on the 68 Board layout on the CD to the 33k/500pf like your 69 Board layout on the CD?

2) On your Reference Cd the 68 and 69 board both have the (2) 470k ohm/500pf connected together. Does this 500pf get replaced with a with one of the cermic caps you sent.

3) You sent me some ceramic caps with that kit.
I have (2) VSP 471k 2KV <----------- I know one is for the phase inverter circuit, where does the other one go?
I have another Ceramic cap that reads
47K 1KV <--------------------No 3rd digit is this 470,000 pf? Was this one intended to go with the 470K ohm pair instead of the 500pf, or should it go with the 33k you sent me.?
I have another Ceramic Cap that reads VSP 101k 2KV.
(One of these caps might be a left over since I got a presoldered bus wire Pot assembly off you) The presolder one has a different cap on the Vol 1 pot than any of these. It reads VSP 561K 1KV.. Should I change to one of the other ones ceramics listed above?
.022uf PI caps. .0022uf cap in the bright channel V1.


.0022uf cap ?
With my 68 kit you sent .022 across the board. (7 total)
The 3rd Cap from the left that connects to V1 Pin1, and Pin 1 of Volume 1 Pot is .022 like the 68 board on your REF CD, but the PI caps are .022 like the 69 Board on your ref CD. I also have the 100k NF, and (2) .22uf (filter Caps?) like the 69 Board layout on your cd.

So basicly mine is a 69 like on your cd, with a jumpered cathode on V1 pin 3 to 8 (no .68uf/2.7k combo), and a .022 cap on Volume 1 instead of the .0022. And an bunch of cermic caps I'm trying to figure where to use.

Sorry for the long winded post, butit seems like there are 3 board layouts for the 68. The one on your Ref CD, the one in your above quote, and what you sent me?

Would those be late 68, early 68 and Eddie spec respectivly?

Here's jargon question for anyone reading this far. George was writing about the ".0022uf cap in the bright channel V1" Is he refering to the "bright cap" on Channel 1? Or is the bright cap the little ceramic cap that is soldered right onto the Volume1 Pot. I get them confused. That's why I say 3rd Cap from the left that connects to V1 Pin1, and Pin 1 of Volume 1 Pot. Pesky Jargon!

To anyone reading this: George has been awesome. He sent me enough parts to build it anyway I want. I originally was going for the 68 spec like on his ref cd. I just wanted hear what it was like compared to the 69 I built. Which I'm very pleased with BTW. I was a little thrown off because what he sent me didn't match what was on his CD as listed above. He must thought I wanted Eddie Spec, because I got the MM ugrade. Thus all the ceramic caps.

When I called him he was very cool and sent me extra parts to do it both ways, but now I'm at the last stages of this amp build and my curiosity is getting the better of me. I want to try those Cermics to see if I like the difference.

Mike

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Post by VelvetGeorge » Mon Feb 07, 2005 1:47 pm

Mike, I did adjust some of the components and values based on our conversations.

In trying to create this timeline, I have realized that the specs I've been using are too vague. And I was calling the 68 circuit something closer to a 67. But not really accurate to either era.

So I'll be updating the circuit descriptions and renaming the board kits to reflect this new knowledge. I'll try to get new layout diagrams for each era as well.

George
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Post by mightymike » Mon Feb 07, 2005 4:12 pm

George,

I want to try out the setup you sent. I thought about it, and changed my mind. I'm almost done with the amp. All that's left is to solder in the preamp tube's sockets, and the 3 little caps on the board and I'm done. I just have 3 questions.

1)Were the (2) VSP 471k 2KV Cermic caps you gave to be put where the 500 pf caps are on the 69 board?

2) Was the other Ceramic cap that was labeled 47k intended to be put where the 47pf is?

3)Where does the VSP 101k 2KV that came with the kit go.

Thanks, Mike

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Post by Guest » Mon Feb 07, 2005 8:31 pm

Ned, do you know if that '67 catalog (the yellow, white and black one) is floating around the internet anywhere?

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Post by mightymike » Mon Feb 07, 2005 9:37 pm

I have everything soldered except for those 47pf and the 500pf that goes with the 33k. Screw it, I'm just gonna go with the Silve Mica. I wanna play. I'll experiment later.

So Basicly I have a 69 board, but shared on V1, and a .022 instead of the .0022. Other than that it's like your 69 Drawing. I'll be firing it up in the morning.

Goodnight

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Post by VelvetGeorge » Mon Feb 07, 2005 11:18 pm

Mike, the 471 is a 470pf, it goes in place of the 500pf on the diagram.

The 47k is the 47pf. And the 101 is a 100pf to try in place of the 47pf in the PI. Some people claim the EVH amp had that value. It does seem to take away some fizziness.

George
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Post by mightymike » Mon Feb 07, 2005 11:35 pm

VelvetGeorge wrote:Mike, the 471 is a 470pf, it goes in place of the 500pf on the diagram.
There's 2 500pf Caps on the 69 board. You sent me 2 of those 470pf caps.
Do they replace both 500 PF caps?
The 47k is the 47pf. And the 101 is a 100pf to try in place of the 47pf in the PI. Some people claim the EVH amp had that value. It does seem to take away some fizziness.

George


Interesting. I'll have to try that out once I get Voltage at pin 5, and my choke stops smok'n. :oops: :cry:

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Post by Ned B » Tue Feb 08, 2005 12:49 am

Guest,
That '67 catalogue I got on ebay three years ago was the only one I've ever seen available. I only discovered its existance from that auction which called it a '66 based on its preceding "Roy". Those first five that procede the stapled blooklet catalogues seen rare. Other than asking peolple like Paul at Ampaholics, ebay seems the major market. I have access to a highend Konica if you would like a quality scan which I would be happy to send you.

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Post by Guest » Tue Feb 08, 2005 10:03 am

Here's a link to a preamp schematic representing one of the circuits offered in early 1968 (model 1959) era amps.

http://hometown.aol.com/tommietuna/myho ... index.html


Ned, I'll e-mail ya about sending the scans of that catalog, ok.

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Post by tonebucket » Thu Apr 21, 2005 3:17 pm

guys I have been checking the forum out know for 2 weeks and Thought I would join in.

I was thinking if anyone had thought about compiling the specs of the different models into circuit board diagrams.

I don't mind compling any info as I am designing a 59 era circuit myself.

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Post by Guest » Tue May 24, 2005 6:14 am

Anonymous wrote:

This amp was made in early 68....from what i can tell. However, I have found something which i believe could be a ~reasonable~ indicator (in the last few years that i have seen, played and tinkered with these things) of the year of these sacred amps....

I have never seen a 67 (or before) marshall amp with the later series brighter yellow resistors....cant remember who made them....a czech/yugoslav company (Iskra maybe???) Whereas, On every ali chassi amp i have owned/played/seen, they were all the much darker red/brown types....ALl the amps i have seen that had these later series resistors seemed to always be steel chassis, starting approximately in 1968....

Interestingly, ecery steel chassis amp i have seen always had these nwer style brighter yellowy resistors.....i hope you know what i am talkign about here?
Well, I do have a plexi "super 100" amp, KT66's etc, and it's full of these yellow resistors....

Shaker

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Ralle 500

Post by Ralle 500 » Thu Jul 14, 2005 2:00 pm

Hey George. I got a historical question:
Do you know if there ever were a combination of filtercaps in 100 w plexi as follows:
Tag board: 2x32 uF
PI stage: 32 uF
Screen: two 100 uF or 50 uF ( total value 50 uF )
Mains : two 100 uF or 50 uF ( total value 50 uF )
Thanx a lot
Ralle

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