Marshall MG Series?

[olddawg]

So... I have been told for years by people like SGM and a lot of other purists out there that the Marshall MG series are all pieces of crap. I should say up front that I'm a guy that's been playing for decades out of just about anything and everything. Of course I love my vintage stuff. But... I don't necessarily buy into "the magic of obsolete technology" crap either. I do have a distaste for modelers, they always sound "plastic" to me.

So... A friend of mine gave me a little Marshall MG15 CDR the other day. His roomate left it when he moved. I tell you, for a basic little 1x10" (oops, guess it's an 8") closed back combo, it sounds great. You can dial just about any tone and distortion you want out of the thing. The only thing I see wrong is that there is no clean/dirty footswitch. It has a front panel switch. But damn. I wouldn't think twice about gigging or recording with the thing. It's amazing the bang for the buck you can get nowadays and without tubes I will bet it's reliable......and weighs next to nothing!

[The Dude]

If SGM says it's crap, it must be crap.

[J M Fahey]

MG15CDR in particular is VERY good sounding, way better than similar competition from other established brands.

As of the other guy:

SGM and a lot of other purists

"other" implies "he's also .... " and he's not at all.
He's just an asshole.

A real purist is something else, and if he's true, I respect him, even disagreeing.

Not exactly SGM who just had a very defined list of "enemies"

[The Dude]

...... "other" implies "he's also .... " and he's not at all.
He's just an asshole......

[olddawg]

MG15CDR in particular is VERY good sounding, way better than similar competition from other established brands.

As of the other guy:

"other" implies "he's also .... " and he's not at all.
He's just an asshole.

A real purist is something else, and if he's true, I respect him, even disagreeing.

Not exactly SGM who just had a very defined list of "enemies"

I just meant purist in the sense that believing it has to be a tube amp to sound good or even be usable. But you see it all over the Internet. MGs suck. Maybe the larger ones do? This little 15 watt model certainly doesn't. Anyone have a schematic?

[g1]

How about purist of B.S., does that count?

[g1]

Well, I guess to think that way you have to start off with the mindset that "if it's not tube it's crap". Then you don't even have to listen to it, you just know. I guess you meant tube purists, which I think would also be too good a term for SGM.

[Jazz P Bass]

A JFet mute circuit would have been a nice addition.

The ones that I have worked on had a rather annoying thump at turn on.

[Enzo]

A JFet mute circuit would have been a nice addition.

On SGM or the Marshall?

[J M Fahey]

The distortion is *very* simple, just a full gain Op Amp and red/green Leds in the NFB, *but* all signal (including clean) is later passed through a 30 dB/oct lowpass filter , then the power amp has also a "warming" mid bass boost and headphone jacks have their own extra hi cut filter.

They were serious on not letting anybody call their amp "SS buzzy" .

To boot, the cabinet is somewhat larger than the average beginner 15W amp and last but not least, the supplied 8" speaker is very good, way average beginner amp type.

In all, I guess the particular Project Manager took his job seriously, without too much pressure from bean counters.

[Chuck H]

This thread is too much fun on a couple of levels

I don't wish to derail it, but it seems to have resolved with the schematic. Before I change the direction a little I'll throw my 2C in on the "purist" aspect. In this case there are bound to be rock and metal Marshall loyalists that see any SS Marshall device as evil for no other reason than it ain't a tube. Funny then (IIRC) that their Silver Jubilee 30th anniversary model uses diode clippers but has risen in rank as a good sounding model Don't drink the KoolAid.

Now for the derail I promised... Still along the same lines though. I remember playing through a little Roland SS practice amp maybe 13 years ago that was VERY impressive. Great rock and metal distortion tones. Very acceptable cleans. Not so great at that jumpy, dynamic, lightly distorted grind. I think we'll always need tube amps for that. Or will we? GK came up with some pretty good circuits following their silly 2x5.5" speaker thing but before focusing more on bass gear. And the Peavey TransTube stuff has made some headway in the right direction too. I think refinement of SS devices for guitar amps was cut short. I lament that digital technologies are taking over the quest for recreation of our favorite amp tones instead. I fully believe that if the right variables were ever worked out that we could eventually have SS amps that are so close in behavior, feel, performance, whatever, to tube amps that even "players" wouldn't "feel" enough difference to complain. I don't know if any major manufacturer is still carrying the torch in that arena, but I'd rather play through a well designed SS amp than a digital modeler.

[g1]

Couldn't agree more Chuck.
Lack of further development of analog SS gear is to be lamented. A casualty that might not have happened if tubes had just gone extinct like it seemed was going to happen back in the 80's.
Digital modeling is just not the same.

[nickb]

<snip>
Digital modeling is just not the same.

...yet

Is it about time we had a digital modelling forum?

[olddawg]

The distortion is *very* simple, just a full gain Op Amp and red/green Leds in the NFB, *but* all signal (including clean) is later passed through a 30 dB/oct lowpass filter , then the power amp has also a "warming" mid bass boost and headphone jacks have their own extra hi cut filter.

They were serious on not letting anybody call their amp "SS buzzy" .

To boot, the cabinet is somewhat larger than the average beginner 15W amp and last but not least, the supplied 8" speaker is very good, way average beginner amp type.

In all, I guess the particular Project Manager took his job seriously, without too much pressure from bean counters.

Yeah I saw that. It's a very common circuit/method... What I don't understand is why other brand amps with the same basic architecture don't sound nearly as good? I've never used a Marshall dirt box, but if the old Marshall Gov'ner, etc uses this circuit and sounds anything like this, I can see why they are popular. It certainly sounds a lot better than the "Valve State" and the "Lead MOSFET" Marshalls I have played to my ears. At least this little MG does. I have a functional Lead 100 MOSFET chassis setting in a box in my garage. It was better used clean like a Twin Reverb. I built an 18 watt clone in the head box.

[J M Fahey]

It's a very common circuit/method... What I don't understand is why other brand amps with the same basic architecture don't sound nearly as good?

Not same architecture:

30 dB/oct lowpass filter , then the power amp has also a "warming" mid bass boost and headphone jacks have their own extra hi cut filter.

Guv'nor, as good as it sounds, has nothing like that, and can easily be found unbearably buzzy , specially in so called "pedal unfriendly" amps.

EDIT: never learnt to simulate, can somebody please do and post resulting curves?
It's built around IC5 , everything between R13 and C48 .
Two active 12 dB/oct filters with a third passive 6dB/oct one sandwiched between them.
If this does not *drastically* alter squarewaves passing through it, don't know what will .
Thanks