#1
Okay, I've been looking at the range of Marshall JCM800s. There's quite a few, but I became really curious as to why the 1987 standard lead models have 4 input jacks. I know that there's either the normal input (input 2) or the high treble input (input 1), but why is there two of each? Also the volume knobs are labeled for the inputs; does this mean that each knob controls the volume for a seperate input? And if this is the case how do you control the levels of gain on each channel. I'm confused, does anyone know anything about this?

Here's a link to the page on the Marshall site if this helps (it's the second diagram down, that I'm referring to):

http://www.marshallamps.com/heritage/jcm800/jcm800_02.asp
#2
Well there is normally two inputs on jcm800's.
One for a higher gain circuit (designed for low output pickups) and the second is a lower gain circuit (designed for higher output pickups). This said, 99% of people ignore this and plug into the higher gain input.

Epiphone Les Paul Standard w/ SD Alnico Pro II's
Fender Aerodyne Telecaster & Stratocaster
Marshall JCM 800 4104 combo


E-Married to Funny_Page
#3
Right, that explains alot. Thanks. Do you increase the gain as you increase the volume on each channel, or are the volume 1 and 2 knobs just master volume and pre-amp volume relabeled?
#4
My jcm is a single channel so I can't help you there! Sorry!

Epiphone Les Paul Standard w/ SD Alnico Pro II's
Fender Aerodyne Telecaster & Stratocaster
Marshall JCM 800 4104 combo


E-Married to Funny_Page
#5
The drummer in my band who barely plays guitar inherited a JCM 900 and two 1960A marshall cabs... what a douche, he doesn't even know how to dial it in...

He bought a line 6 distortion pedal and turns it on with the amps distortion on at the same time. Needless to say, he disgraced the name of Marshall almost more than the MG series.

/spam
My gear:
PRS SE custom
~!~--Peavey XXX super 40 EFX --~!~
Peavey VK 112

===WGS Vet30
===JJ power tubes

---Pedals:
-ISP Decimator
-Digitech Bad Monkey
-Crybaby wah
-Korg Pitchblack
-Danelectro FnC EQ
#6
TS;
Do you have "volume, gain, bass, middle, treble, presence" as your channel controls and then do you have master volume knobs as well?

Because if you do, you can max the gain (preamp saturation) and max the channel volume (poweramp saturation) then use the master volume to set to whatever volume you want.

This means you can have the incredible marshall roar at any volume you want!

Epiphone Les Paul Standard w/ SD Alnico Pro II's
Fender Aerodyne Telecaster & Stratocaster
Marshall JCM 800 4104 combo


E-Married to Funny_Page
#7
Quote by Cmd. Cool
Right, that explains alot. Thanks. Do you increase the gain as you increase the volume on each channel, or are the volume 1 and 2 knobs just master volume and pre-amp volume relabeled?


The amp you're talking about is the JCM800 version of the 1959 super lead or 1987 50 watt, they were still made for a while in the early '80s but not in large numbers given the success of the master volume amplifiers, you see them every now and then but they're not particularly common. It has the same front panel setup of an old jmp (whether 50 watter, super lead, etc, plexi or metal panel) or a JTM45.

There are two channels, a bright and a normal channel, and high gain and low gain inputs for both channels. Thus you get 4 inputs, and you are correct in saying that volume 1 and volume 2 are channel volumes, they're not a master and preamp gain control.
Quote by Chrisiphone
TS;
Do you have "volume, gain, bass, middle, treble, presence" as your channel controls and then do you have master volume knobs as well?

Because if you do, you can max the gain (preamp saturation) and max the channel volume (poweramp saturation) then use the master volume to set to whatever volume you want.

This means you can have the incredible marshall roar at any volume you want!

No you can't, a master volume comes before the power amp. Always. You cannot place a master volume after the poweramp, thus there is no way to get power amp saturation at low volumes without an attenuator or some kind of power scaling.
Last edited by al112987 at Jan 25, 2009,
#8
Quote by al112987
No you can't, a master volume comes before the power amp. Always. You cannot place a master volume after the poweramp, thus there is no way to get power amp saturation at low volumes without an attenuator or some kind of power scaling.


Ahhh I was misinformed, thanks for flagging it up!

Epiphone Les Paul Standard w/ SD Alnico Pro II's
Fender Aerodyne Telecaster & Stratocaster
Marshall JCM 800 4104 combo


E-Married to Funny_Page