Evolution of the 100 watt superlead circuit

Everything from original vintage Marshalls to reissues.

Moderator: VelvetGeorge

User avatar
VelvetGeorge
Site Owner
Posts: 7205
Joined: Tue Oct 14, 2003 5:12 pm
Just the numbers in order: 13492
Location: The Murder Mitten
Contact:

Post by VelvetGeorge » Thu Jul 14, 2005 4:22 pm

My '67 has those values except for the daul axial cap on the board. It's a dual 20uf. But I'm not positive that it's original.

George
Check out Plexi Replicas for my personal amp builds...
Image

Billy Batz
Senior Member
Posts: 8566
Joined: Fri Dec 10, 2004 8:49 pm

Post by Billy Batz » Thu Jul 14, 2005 6:26 pm

Theres no way those values didnt come out of the factory at some point between 67 and 68.

Ralle 500
Senior Member
Posts: 295
Joined: Fri Jul 08, 2005 6:13 am

Ralle 500

Post by Ralle 500 » Thu Jul 14, 2005 6:41 pm

What I feel coplicates things about this is that it seems like any combination were possible at that time. How knows what values came out from the factory in those days... I think it's quite possible that a dual 20 uF were a stock in some amps.
Ralle

Ralle 500
Senior Member
Posts: 295
Joined: Fri Jul 08, 2005 6:13 am

Ralle 500

Post by Ralle 500 » Sat Jul 16, 2005 7:45 pm

Another historical question: Were there ever a singel 50 uF in the PI filtering, or only using one of the two 50+50 uF during -67 -68?
Ralle

Guest

Post by Guest » Tue Jul 19, 2005 8:35 pm

20uF+20uF filter cap(s) were used on on Marshall's for the pre-amp stage (the one located on the main tag board). Generally, it's like a late-'67 or early-'68 thing. Regarding the "using of one 50uF leg of a 50uF+50uF filter cap" from the factory.....Not. If it was a dual can (e.g. 50uF+50uF) then both sections were used. Screen filter caps for this era (late-'67 early-'68) usually always ran the 32uF/450vdc singles or the 32uF+32uF dual caps.

Ralle 500
Senior Member
Posts: 295
Joined: Fri Jul 08, 2005 6:13 am

Post by Ralle 500 » Wed Jul 20, 2005 11:44 am

Anonymous wrote:20uF+20uF filter cap(s) were used on on Marshall's for the pre-amp stage (the one located on the main tag board). Generally, it's like a late-'67 or early-'68 thing. Regarding the "using of one 50uF leg of a 50uF+50uF filter cap" from the factory.....Not. If it was a dual can (e.g. 50uF+50uF) then both sections were used. Screen filter caps for this era (late-'67 early-'68) usually always ran the 32uF/450vdc singles or the 32uF+32uF dual caps.
Thanx for that info, Guest. That cleared a lot of things in my mind. Thinking, as long as it's possible, then why not... In that way one could never know, right? :wink:

Mr G
Senior Member
Posts: 124
Joined: Thu Jan 27, 2005 6:06 am

Mr G

Post by Mr G » Wed Jul 27, 2005 6:46 am

20uF+20uF filter cap(s) were used on on Marshall's for the pre-amp stage (the one located on the main tag board). Generally, it's like a late-'67 or early-'68 thing. Regarding the "using of one 50uF leg of a 50uF+50uF filter cap" from the factory.....Not. If it was a dual can (e.g. 50uF+50uF) then both sections were used. Screen filter caps for this era (late-'67 early-'6Cool usually always ran the 32uF/450vdc singles or the 32uF+32uF dual caps.
Sorry to be impolite Mr Guest, but what you have stated is not quite true....I have personally seen dozens of plexi era marshalls where they used dual capacitors all over the amp yet only wired up half of the dual can (especially on the screens and the tag board). The value(s) of the screen filter caps used were very much dependant on what they could get their hands on at the time from the army surplus stores down in the east end of london (or direct from the manufacturer/distributor if possible) - at least thats what Ken Bran told me about 6 months ago when i spoke with him on a conference call with Danny and Phil at Marshall's :-). I'd like to think he knew what went on in those days....As long as the screens and the voltage doubler figures basically balanced out - they used what they could get their hands on and that would fit - No Rhyme or Reason...it just evolved that way.

International assembly and production quality standards like ISO 9001/2 and various other QC processes had not yet been invented - which would as of today (currently up at marshall) dictate exactly what to use, how and where to use it - including testing and measurement. The assembly line ladies at Marshall today have set visual descriptions and process sheets infront of them to make sure they solder and wire the things up right...they are not engineers or valve audio enthusiasts....they simply follow instructions - the opposite of what was done 30 odd years ago. Remember, back in the late 60's they had maybe 20-30 people tops working 16 hours a day under Ken's direction churning out all these different amps...they got what they could and wired it up...hence so many unusual variations on such a regular basis - until they tooled up for massive volume production runs in the early seventies through to today.

If you really want to speak to someone who has seen and heard more than any other person in history regardign old marshall, vox and orange amps then just call my dear friend Carl Nielson at Rockbottom music +44 20 8680 1042. He will set you straight! - and probably tell you some funny stories about Hendrix making tea for his staff at his store in the late 60's.

Guest

Post by Guest » Sun Jul 31, 2005 8:59 pm

Once again it's good to hear from you Mr. G, and that's some interesting info you stated. I; like yourself probably; just cautiously state what ever facts I know to be true (at the time) regarding Marshall amps. I have never seen a dual filter cap only having on leg wired up, nor has anyone else (with the exception you and possibly Carl Nielson) I ever spoke with. With these amps being so old now it's also possible that owner(s) have disconnected a leg on a filter cap to reduce the filtering for whatever reason too. Were not even talking about that many amps (roughly 3000) that have these types of filter cap arrangements. Dispite Marshall's variation in parts/values for filter caps they seemed to "stay the coarse" rather well. For example: If they couldn't get say a single 32uF/450vdc caps for the screens then they'd use a 32uF+32uF caps and go with the parallel/series arrangement.

Mr G
Senior Member
Posts: 124
Joined: Thu Jan 27, 2005 6:06 am

Mr G

Post by Mr G » Mon Aug 01, 2005 2:51 am

Hi Guest (Do you have a board name?)

Very few truly untouched original marshall's exist today (maybe a few hundred globally), although I have personally found that on some of the very early jtm 45's and several 45 100's (including mine) the tagboard cap (often a stumpy grey dual RS 32ufx32uf can) was often wired up for half its potential filtering (from the factory) - I put this down to availability of the size and microferad value of can's at the time (have you ever seen the size of some of the Hunts, ERR, Daly, RS cans in those days? Some can barely fit inside a chassis!). Several of my american friends (Brian Wallace and Ray Domzalski) have also seen early marshalls that use only half the filter can where applicable (on both the pre and power amp side of the turret board).

I'll try and get some pictures for you of these tag boards wired to only one half.

Guest

Post by Guest » Mon Aug 01, 2005 8:32 pm

Sorry, I don't have a board name....One day I'll register!
I think I know where your coming from about the JTM 45's and JTM 45 100's. Marshall probably did the one leg of a 32uF+32uF on the tag board because they were still using the earlier H.T. configuration with just the one 10k/1w voltage dropping resistor. Although, I still never seen/noticed it (one leg of a dual cap being used). Also, I know what you mean by some of the "jumbo" sized filter cans. I think one of the worst is the Dubilier of England ones....Their diameter ain't bad but the length is terrible for the tag board. Brian is a great guy as is Ray. A lot of the info on Brain's site for the 50w amps I gave him. As a matter of fact, I've got an update for the 50w page I still have to send him. Also, the pictorial page was a joint effort between Brain and myself. I sent him something like 500+ pictures for the page which took like 15 days. Ray makes some killer tag boards which I've used on clones in the past.

electricskychurch
Senior Member
Posts: 968
Joined: Fri Apr 22, 2005 9:08 pm
Location: france

Post by electricskychurch » Thu Aug 11, 2005 8:02 pm

as it seems it's the topic to post unusual or hard to find infos, here are a few ones.

i have a 66' jtm 100 super pa with mostly yellow resistors, but i can't swear they are all original.
there is very few or maybe no red solder dye on this amp so i don't know if solders are original.
i tried to find some pictures of other amps from the same era to see if they had red solder dye but i couldn't find the answer.

i read somewhere that the metal panel didn't came before july 69' (maybe doyle's book) but ned seems to say it could be a few month before.

i have a 69' jmp super pa 50w that has a plexi back and a metal face.
i'm not sure if the inspection sticker is true or not cause it's not the usual one, but a blank sticker on the side of the chassis , with another sticker (colored) on it written " inspected" or so .
it's written 5/6 /69. serial is SP 10479
its OT is the earlier 784 139 that is larger on the metal sides, with no holes on the corners.
this amp has much low end and low mids, i have to leave its bass control on 2, whereas i turned it to a split cathode 69' lead circuit (but without v2 0.68 uf cap).
more low end that my 74' 1985 pa (50w) turned to lead.

i also have a red custom color superlead from 25/3/69 SL/A 10933 that has some half transparent WIMA caps for all the 0.022 uf (the 0.0022 and the 2x 0.68 for v1 and v2 are mullard) and they all have original red solders.

Guest

Post by Guest » Mon Aug 15, 2005 9:41 pm

"electricskychurch",

The yellow resistors found in a aluminum chassis amp isn't all that uncommon. If the amp is from the tail end of aluminum chassis series (aluminum end block style) then the yellow resistors show up more readily. The use of the red dye or even the yellowish dye really didn't start til latter on with greater frequency. I think we have to keep in mind that there was more than one person building the Tag boards. Therefore, a few stations may have been loaded up with the yellow resistors were as other stations my have still had the red resistors. Also, (an educated guess here) 50w boards were assembled at different stations than the 100w boards despite the difference of only two resistor values. Same holds true for the 100w Tremolo boards. This is how you see things like the use of RS 0.68uF bypass caps on the 100w Tremolo amps and not on any Super Leads.

That Super Lead (SL/A 10933) sparks my interest.....Any chance you've got pictures of the amp you can post?

User avatar
rockstah
Senior Member
Posts: 12481
Joined: Thu Sep 15, 2005 12:28 pm
Just the numbers in order: 7
Location: Austin Texas

Post by rockstah » Fri Dec 30, 2005 2:20 am

so was a 67 ever even an aluminum chassis? or aluminum pretty much over in 66...?... :)

JQuick

Post by JQuick » Thu Feb 09, 2006 5:07 pm

I have an original '67 Marshall 200. It indeed has an aluminum chassis. I don't know how it holds up the massive Partridge transformers! No reinforcement blocks either!

fkh
Senior Member
Posts: 63
Joined: Mon Apr 10, 2006 3:42 pm
Location: Denmark

please date my Marshall

Post by fkh » Wed Apr 19, 2006 1:54 pm

Can any of you clever guys tell me if this one is a 67 or 68 please.

It has "the narrow vent"on top of the kabinet.

Image
Image
Image
Image

please feel free to comment :D :D

For more pics :http://casper-hansen.dk/fkh/67sl/
Last edited by fkh on Wed Apr 19, 2006 2:17 pm, edited 1 time in total.

Post Reply