Marshall model 1987X to mod or not to mod...

[Slobrain]

Hey folks,

I won a Marshall model 1987X on eBay and just got it this weekend. It was made in 2004. I have to say it doesn't seem to be built as good as the old ones. The Plexi front and back panel is really thin and wimpy...

Its a nice sounding amp but still has the shortcomings of the old non master amps, the treble volume jump is too quick and the treble channel is a bit shrill. Seems there has to be mods out there that make this amp pedal friendly and volume friendly as the fender amps. I personally don't like to crank Marshalls due to many years ear abuse that caused me to have damaged hearing years back in 1995.

I like an amp like a Fender Bandmaster or twin reverb that I can turn up and use a distortion pedal to get my sound. A Marshall non master has a tone that I like but the gain stage setup that Marshall built into these are gained up too much.

Anyone out there have any suggestions on how to make this amp more fender volume friendly but retain that Marshall tone?

Also I noticed this amp has 2 pots on the circuit board. the old boards had only one pot for biasing. Does anyone know what V1 and V2 are?

Thanks

[dai h.]

hi, (just some non-expert general suggestions) :

-experiment with the pickup damping by increasing cable capacitance (or use an actual capacitor) to try to move the harsh peak so you have less boost at those harsh frequencies

-try a hotter pickup, or some kind of boost (EQ, OD, etc.)

-darker speaker(s) should help

re: the volume IMO the earlier (up to around '80) versions that have the lower B+ power transformer are not as loud and seem a bit sweeter. (Obviously) changing the PT would be a pretty drastic (and expensive) mod, so maybe try a post-phase inverter MV.

Personally I like the (supposed) EdVH mod (which just seems to be an added large bypass cap on V2a cathode which helps beef up the bright ch. somewhat; oh and a 100k feedback R). Experimenting with increasing the PI output coupling caps might be good to try also. Having said that though, the "Normal" channel (has wider freq. range than the bright with a more extended low freq. response) seems to work better generally with efx.(possibly if the Bright ch. input is driven better with some kind of lower impedance buffer/driver stage, maybe it'll work better with efx.(?)).

re: the extra trim pot, I think the new one is for the fake filament center tap balance (to adjust for less hum)

[pdf64]

What don't you like about the tone when plugged into the normal channel?
Do you normally switch the bright on, with a bandmaster or twin reverb?
Pete

[Slobrain]

What don't you like about the tone when plugged into the normal channel?
Do you normally switch the bright on, with a bandmaster or twin reverb?
Pete

Well, Its too trebly, I probably need to change the bright vol cap to a 100PF like I did on my old Marshall 1987, or just remove it all together. I like both channels blended but the treble channel is too much. Also thinking about changing the 12AX7 to a 12AY7 like the old fender Bassmans to get the volume more controllable. I never did understand why Marshall did the bright vol setup like they did...

[Slobrain]

anyone have a schematic for the newer model 1987X with the fx loop? I sure could use one...

[pdf64]

'What don't you like about the tone when plugged into the normal channel?
..
Well, Its too trebly, I probably need to change the bright vol cap to a 100PF like I did on my old Marshall 1987'

That's the treble channel - how about the normal channel, which doesn't have a bright cap?

See p4 of http://www.webphix.com/schematic%20h..._50w_1987X.pdf for the fx loop.
Pete

[Slobrain]

What I want to do with this amp is to get it loud but clean, I like to use pedals on a clean sounding Marshall, that has always worked best for me. I like to blend both channels to get a tone I like.

Most guys want to crank a Marshall for distortion and I used to like to do that too but to preserve what's left of my hearing I would rather just make the amp loud and clean so pedals can do all what I want them to do.

In the 60s there wasn't any good distortion pedals but now these days we have tons of good hi gain pedals that sound great. You can do a YouTube look at guys like Pete Thorn that demo some awesome distortion pedals like the Carl Martin Plexi pedal and others like that. After hearing Pete Thorn play on those pedals its very inspiring to want to do that too. Of course Pete is an awesome guitarist.

I guess I'll do some mods to clean up the gain. I always felt like Marshall non master amps were always too gainy when you wanted to do the sort of Fender vibe.

[loudthud]

I like to connect both channels and use the volume controls to balance lows and highs. The bright cap (C5) on the bright channel is way too large, something between 100pF and 470pF helps. Some amps change C4 to 2.2nF. I'm currently working on a TW Express clone. I tried a VVR setup just using a variac and a filament transformer. It works well down to 1/4 power (60V line) without any other mods and provides usefull control of volume, just not down to bedroom levels. Very little change in tone. For some reason these amps don't do clean very well.

[888guitars]

Mar var master volume mod!

[dugdiamond]

Not to be too much of a smartass, bbut why did you bid on a Marshall. Maybe should look for a 64 Bassman or Bandmaster for trade?

[Slobrain]

I actually have a 67 bandmaster with a upgraded Classic tone 50 watt OT. it sounds real good. The reason for the Marshall mod is the sound of the Marshall, even clean with pedals it retains that same character that makes a Marshall sound like a Marshall. I ran that setup in the mid 80s and it always worked well, but when I got married in 87 I did the stupid thing by selling my Marshall rig... a Marshall 50 watt MK2 1987 head built in 1972 with a late 60s Marshall 4x12 with the original 30 waters.... Still kicking myself for that one...

I did tame the new amp though, removed the bright cap and used a 12AT7 for the phase inverter. works like a charm now...