Early '70's Marshall experts. What do you think of this Canadadian unit from late'73

louis

Silver Supporting Member
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4,262
I had one of those for years and apparently
the transformers were paint peeling Monsters
and lack some cream smoothness and
this is exactly how mine sounded !

Cold and Harsh !

But then again ,no amp sounds the same !

Lou
 

michael.e

Silver Supporting Member
Messages
20,526
I know what they sound like. I have had 6 different early Marshall examples. I am asking about the board/innards. How original, any funkiness, etc..
 

Steve Ouimette

Silver Supporting Member
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562
For the most part you're in good shape. Looks like one of the mustard caps is gone on the far left of the board and they've got new bias supply caps and a few other part changes but it's largely intact. I didn't see any pix of the iron, which obviously makes up a huge part of the tone.

How does it sound?
 

louis

Silver Supporting Member
Messages
4,262
I know what they sound like. I have had 6 different early Marshall examples. I am asking about the board/innards. How original, any funkiness, etc..
I think that the internal was fine but I've read
that the transformers were too strong but
don't remember where I read it !
 

michael.e

Silver Supporting Member
Messages
20,526
I think that the internal was fine but I've read
that the transformers were too strong but
don't remember where I read it !
It really depends on how you use them imo. I use my guitar volumes extensively. Some of my favorite clean tones come from the '70's JMP's.
I have gigged with these and have not had to peel paint in order for them to sound full and rich.

Great amps!!
 

louis

Silver Supporting Member
Messages
4,262
It really depends on how you use them imo. I use my guitar volumes extensively. Some of my favorite clean tones come from the '70's JMP's.
I have gigged with these and have not had to peel paint in order for them to sound full and rich.

Great amps!!
Like I said , every amp sounds different ,
mine were late 73 and early 74 100 watters
and I never got the sound you had with yours ,
asked my tech to tweak it but the problem was
my transformers reading too strong.

Lou
 

Belmont

Member
Messages
3,465
Like I said , every amp sounds different ,
mine were late 73 and early 74 100 watters
and I never got the sound you had with yours ,
asked my tech to tweak it but the problem was
my transformers reading too strong.


Lou
is this for real?
 

louis

Silver Supporting Member
Messages
4,262
is this for real?
Sorry about that ! I might have used the wrong technical term but I
remember that my tech told me that the voltage
was very high compared with a 68-69 .

Believe me when I tell you that I wish I could
be a tech or know more about amp building
cause I would build myself a hell
of an amp . One thing I know is that I have
good ears as a musician and know what 3D Complex
warm creamy juicy and Harsh tone means !
 

drbob1

Gold Supporting Member
Messages
28,593
Which could make perfect sense, transformers were designed for 115v then and you're getting 125-130v in much of the country now. Some of my amps definitely sound better at a more appropriate voltage!
 

Belmont

Member
Messages
3,465
Sorry about that ! I might have used the wrong technical term but I
remember that my tech told me that the voltage
was very high compared with a 68-69 .

Believe me when I tell you that I wish I could
be a tech or know more about amp building
cause I would build myself a hell
of an amp . One thing I know is that I have
good ears as a musician and know what 3D Complex
warm creamy juicy and Harsh tone means !
hey no need to apolgize, I've just never heard of this before.
old 100w Marshalls are notorious for putting out more wattage than stated, I wonder if that's what he meant.
I've got a 75 (Canadian model)with the laydown transformer, best amp evar.
 

michael.e

Silver Supporting Member
Messages
20,526
I was using a variac with all of my vintage amps. Keep the voltage down to 110/115. Best for all components.
 

Franktone

Gold Supporting Member
Messages
3,120
I rented one once in the late seventies to use for a large outdoor party. The other guitarist rented a brand new 100W double stack with master volume which was absolutely beautiful sounding. But the one I rented from a different store was a non master volume 100 from around 1973-1975 erra and they gave me a double stack with HiWatt cabinets. That thing was incredbly loud and I ran it full up to get the edge of break-up sound with my 68 Les Paul converted to large humbucking pickups. Man was that thing loud outdoors and only started to breakup nicely at full volume. After that night I kinda realized that it was too much power for me. About 5 years later I wound up getting a HiWatt 100 head Hylight from 1981 on a trade for my 1982 JCM800 1x12 combo, but I later sold it because again the HiWatt was way too overwhelming for its power. I'd like to have the HiWatt today just for TGP photos with my guitars. Oh well. I later bought a used Marshall JMP 50W 2x12 (G1265's) combo from 1981 and still have it, and even it is way too loud for today's demands, but its used for outdoor concerts and parties where the PA is not up to par. The JMP 50W combo is not going anywhere.
 

Franktone

Gold Supporting Member
Messages
3,120
Those radial caps look terrible. Who does that?
I don't see any radial caps. Are you talking about the glorious mustard caps. Or are you talking about the heavy duty wire wound resistors across each EL84 socket? Or is it the white cap.
 

humbucking

Member
Messages
157
The radials are in the bias section. Simple enough fix though. The .68 Mustard for the first gain stage has been replaced, but they are available on ebay. Great amp. I have had a few early 1970's JMPs & they rock. You might want to update the filter caps, as they appear to have dimples showing. They may be fine, but they do have a lifespan of roughly 15 years before they start getting questionable. Worst case scenario is that they explode & muck up the amp. If they have dried up, they can cause the amp to get loose in the bottom end & flub out. You want those 1970's Superleads to be super tight & immediate along the entire spectrum! That what they were designed for.
 




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