Marshall 2203: JMP VS JCM800

[Techdeth]

Man it’s been too long to have any idea of a guess

You got great videos of my amp

 

[Dale B]

View attachment 423225
Hiwatt you say? It is a good combo.

Yep! I love Hiwatts!

 

[Eazy-ESP]

I hear it the way described in first post when I watch YouTube demos. Not a good source I know, but the 800s do seem brighter, etc. was playing my JMP for first time in ages last night coincidentally. I’ve only ever owned JMPs. 78 I regret selling and the 80 I have now. The 80 seems more evil and gainy than my 78 was.

 

[BesaMoogie]

I dove a little bit into that topic and here is, what I`ve found out so far. Be prepared as this is going to be nerdy:

First, there`s a distinction between the 2204 and the 2203 when talking about the two holers released between 76-83. Don`t mix that up.

2204:
The 2204 had a lower B+ up until mid 1982. PV is around 380 Volts. In late 1982, this changed to 450 Volts, but Marshall actually did not put in an additional 10K resistor in the in the B+ supply line leaving you with a higher voltage throughout the whole preamp. Early lower voltage 2204 did not "need" this resistor as the voltage was all around lower from the beginning.
The 2203 always had all of the 10K dropping resistors and the high 450 voltage.

2203:
Like mentioned above, no significant voltage changes and all 10k dropping resistors present.
The cap brand did change throughout the whole production years. Changing on cap in a circuit will not have a lot of effect, but building a whole circuit with one brand will make differences IMO.

Iskra MKT caps:
introduced in 1980. They come as red or white rectangular caps and have a star-sign on top

Plessey MKT caps:
a short rund in 1981- 1982. White rectangular caps tha have .022 M 400 printed on top. The caps were only used for a short period and Marshal went back to the Iskra caps.

Phillips MKT and MKC caps:
used mostly in 1978-1979: Yellow rectangular caps. You see both, metallized polyester (MKT) and metallized polycarbonate (MKC) caps.

2203 caps between 1976 and 1978:
Here you see all sorts of different cap brands:
- Phillips Mustard caps, axial and radial
- ITT caps (tan plastic enclosure)
- white Procond caps, dipped shape
- greenish dipped shape caps that I was not able to find out, which brand they were

Earliest 2203 used the Phillips mustard caps throughout the whole circuit. Later you see amps using the above mentioned other brands used in the 0.022uF spots mixed phillips mustard caps (0.68uF and 0.1uF).


Other mentions:
OT`s in 2203: there is some talk, that late 70ies 2203 used diffent or better OTs. Dave Friedman mentioned this at one point.

First 2204 did not have cascaded wiring for V1. I`m not sure, if this is the case for 2203 amps as well.

Cheers!

 

[Jack Luminous]

There are major differences in late 70s 2203/04, early 80s JCM800 2203/2204 and later JCM800 2203/04.
Firts they degraded the tranformers, than dropped the voltage significantly.

Both my '83 2203 have around 480V on the plate so I'm not sure it could have been much higher before.

 

[cardinal]

I've had a lot of 2204s from different years. Generally they sound about the same, but I've had some that imho are far too bass heavy and boomy (to me), and they tend to me JCM era (though I had one JMP that was like this).

The most aggressive one I've played was a JCM from 1990 that had tons of gain by itself and was really tight and bright.

Right now I have two '79ish 2204s. One is US spec with 6550 and the other is a UK market with EL34s. The UK amp is a bit dirtier sounding, while the US amp is more defined.

 

[FourT6and2]

I dove a little bit into that topic and here is, what I`ve found out so far. Be prepared as this is going to be nerdy:

First, there`s a distinction between the 2204 and the 2203 when talking about the two holers released between 76-83. Don`t mix that up.

2204:
The 2204 had a lower B+ up until mid 1982. PV is around 380 Volts. In late 1982, this changed to 450 Volts, but Marshall actually did not put in an additional 10K resistor in the in the B+ supply line leaving you with a higher voltage throughout the whole preamp. Early lower voltage 2204 did not "need" this resistor as the voltage was all around lower from the beginning.
The 2203 always had all of the 10K dropping resistors and the high 450 voltage.

2203:
Like mentioned above, no significant voltage changes and all 10k dropping resistors present.
The cap brand did change throughout the whole production years. Changing on cap in a circuit will not have a lot of effect, but building a whole circuit with one brand will make differences IMO.

Iskra MKT caps:
introduced in 1980. They come as red or white rectangular caps and have a star-sign on top

Plessey MKT caps:
a short rund in 1981- 1982. White rectangular caps tha have .022 M 400 printed on top. The caps were only used for a short period and Marshal went back to the Iskra caps.

Phillips MKT and MKC caps:
used mostly in 1978-1979: Yellow rectangular caps. You see both, metallized polyester (MKT) and metallized polycarbonate (MKC) caps.

2203 caps between 1976 and 1978:
Here you see all sorts of different cap brands:
- Phillips Mustard caps, axial and radial
- ITT caps (tan plastic enclosure)
- white Procond caps, dipped shape
- greenish dipped shape caps that I was not able to find out, which brand they were

Earliest 2203 used the Phillips mustard caps throughout the whole circuit. Later you see amps using the above mentioned other brands used in the 0.022uF spots mixed phillips mustard caps (0.68uF and 0.1uF).


Other mentions:
OT`s in 2203: there is some talk, that late 70ies 2203 used diffent or better OTs. Dave Friedman mentioned this at one point.

First 2204 did not have cascaded wiring for V1. I`m not sure, if this is the case for 2203 amps as well.

Cheers!

Marshall is notorious for inconsistency. If someone assembling an amp ran out of a 500pF for the tone stack treble cap, instead of getting up off their ass to find the right one, they'd just use the next closest value, like 680pF or 470pF. If they ran out of 10K dropping resistors, they'd just use an 8K2. If they ran out of a 220K resistor, they'd just use 180K or 150K.

I've opened up tons of Marshalls. One of them I modded lately sounded a little more aggressive than others. A little brighter. A little more mids. Stock, it was almost too much. The owner noticed this but just figured it was a "brighter" amp due to some unknown reason. Well... both the treble mixer and tone stack treble caps were 680pF instead of 500pF. Not a huge difference, but that was why.

Any differences in sound between all these iterations of amps comes down to Marshall being lazy and cost cutting—a lack of consistency in manufacturing. They were too cheap to do it right.

Sure, the brand of components changed here and there. But really, Marshall actually used different values in many places for one reason or another. I've seen it all. For example, they ran out of 0.022uF caps, so they used 0.027uF in stead. "Nobody will notice" is what I'm sure they said to themselves. The assembler just wanted to fill their quota and get paid.

As you mentioned, the BIGGEST difference between all these versions of the same circuit though, is the power transformer and power supply. There are many versions of the PT used and they all put out slightly different voltages. And on top of that, Marshall used random B+ dropper values. Sometimes 10K, sometimes 8K2, sometimes two 10K, sometimes two 8K2, sometimes one of each. I've even seen amps that had 8K2 in EVERY interstage position because they ran out of 10K.

 

[7704A]

Marshall is notorious for inconsistency. If someone assembling an amp ran out of a 500pF for the tone stack treble cap, instead of getting up off their ass to find the right one, they'd just use the next closest value, like 680pF or 470pF. If they ran out of 10K dropping resistors, they'd just use an 8K2. If they ran out of a 220K resistor, they'd just use 180K or 150K.

I've opened up tons of Marshalls. One of them I modded lately sounded a little more aggressive than others. A little brighter. A little more mids. Stock, it was almost too much. The owner noticed this but just figured it was a "brighter" amp due to some unknown reason. Well... both the treble mixer and tone stack treble caps were 680pF instead of 500pF. Not a huge difference, but that was why.

Any differences in sound between all these iterations of amps comes down to Marshall being lazy and cost cutting—a lack of consistency in manufacturing. They were too cheap to do it right.

Sure, the brand of components changed here and there. But really, Marshall actually used different values in many places for one reason or another. I've seen it all. For example, they ran out of 0.022uF caps, so they used 0.027uF in stead. "Nobody will notice" is what I'm sure they said to themselves. The assembler just wanted to fill their quota and get paid.

As you mentioned, the BIGGEST difference between all these versions of the same circuit though, is the power transformer and power supply. There are many versions of the PT used and they all put out slightly different voltages. And on top of that, Marshall used random B+ dropper values. Sometimes 10K, sometimes 8K2, sometimes two 10K, sometimes two 8K2, sometimes one of each. I've even seen amps that had 8K2 in EVERY interstage position because they ran out of 10K.

Hmm... I should trace out my 4104 and see what's going on inside.