Marshall MG Upgrade

[atf]

So 4 years ago, my son(6 years old then) and I went to a music store to pick up some strings and he sees this used shiny Marshall MG15CD for 50 bucks and wants to buy it cause it looks nice. So I buy it, use it like once, and store it away. Flash forward to now, and I'm trying to sell it but he won't let me cause he still likes it. So now I'm stuck with it.

Since I'm stuck with, I decided to give it a looksie, to see what is under the hood. And I see this:

Cheap and analog i know, but that op amp JRC4558DD is apparently a lower noise higher gain version of the one in a tube screamer. Hmm so why does this amp suck so much? I look further and find this:

A junk speaker which I changed to this

And it's finally actually useful. Brighter, rounder, clearer and more articulate even at the highest gain settings. And the whole thing is still cheaper than a new MG! Worth it if you are stuck with it!

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[ehdwuld]

Re: Marshall MG Upgrade

Can't quite read the label on that celestion
Which one is it?

*(Sent from my durned phone!)*

 

[dystrust]

Re: Marshall MG Upgrade

Can't quite read the label on that celestion
Which one is it?

*(Sent from my durned phone!)*

It looks like a Celestion Eight 15.

I have an older MG30 that was my second amp, and I haven't sold it because it isn't worth much of anything. I still use it from time to time when I need to overdub a guitar track and I'm looking for a fizzy or generally crappy tone :lol:

It's also been modified with an external speaker jack that disconnects the combo speaker, and it sounds surprisingly good when run through a decent cabinet.

 

[treyhaislip]

Re: Marshall MG Upgrade

I actually really liked the MG series–don't know what speaker was in mine but I thought it had a very nice sound.

 

[Diego]

Re: Marshall MG Upgrade

I did that with a really crappy Yamaha amp (HY10G-III) that I turned into a head and ran into a 1x12 cab instead of the 1x8 it came with.

Actually sounded interesting.

 

[atf]

Re: Marshall MG Upgrade

It looks like a Celestion Eight 15.

I have an older MG30 that was my second amp, and I haven't sold it because it isn't worth much of anything. I still use it from time to time when I need to overdub a guitar track and I'm looking for a fizzy or generally crappy tone [emoji38]

It's also been modified with an external speaker jack that disconnects the combo speaker, and it sounds surprisingly good when run through a decent cabinet.

I would be interested in that mod. Do you have information or schematics on how to do that? Then I can run it through a greenback cab and see what kind of interesting tones it produces. Could be useful at school talent show jams.

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[dystrust]

Re: Marshall MG Upgrade

I would be interested in that mod. Do you have information or schematics on how to do that? Then I can run it through a greenback cab and see what kind of interesting tones it produces. Could be useful at school talent show jams.

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I really don't know exactly how it's wired since a tech friend of mine actually did the mod work. I'd guess it uses a stereo jack to do the switching, but I'm not 100% sure what he did besides splicing it into the amp's speaker wires and installing the jack in the back of the chassis.

 

[RealtyViking]

Re: Marshall MG Upgrade

I would be interested in that mod. Do you have information or schematics on how to do that? Then I can run it through a greenback cab and see what kind of interesting tones it produces. Could be useful at school talent show jams.

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You could use a Switchraft 13a 1/4" phone jack. The jack sends the signal to your speaker until you plug in a 1/4" speaker jack at which point the output is sent to the cable. The inner contact would go to your internal speaker. The outer contact would not be hooked up to anything. The center contact (which would contact the tip of your speaker cable and moves when you insert the cable) would be connected to the signal coming from the amp.

Just be careful to turn off the amp prior to inserting or removing the 1/4" speaker cable as you might blow your transformer.

Link for Switchcraft 13a

 

[Shooter.556]

Re: Marshall MG Upgrade

I'd like to hear some sound clips.
That is pretty cool! So all you did was change to opamp and the speaker?

 

[atf]

Re: Marshall MG Upgrade

I'd like to hear some sound clips.
That is pretty cool! So all you did was change to opamp and the speaker?

Speaker only


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[astrozombie]

Re: Marshall MG Upgrade

I owned the 50 watt version of this series... I'm sure I got a pretty decent tone out of it but I still think that it was never good for me to use it for gigs.

I do think that this speaker swap must have made for a nice upgrade and a very usable practice amp.

 

[atf]

Re: Marshall MG Upgrade

I owned the 50 watt version of this series... I'm sure I got a pretty decent tone out of it but I still think that it was never good for me to use it for gigs.

I do think that this speaker swap must have made for a nice upgrade and a very usable practice amp.

Yup you nailed the correct keywords there 'usable practice amp' . I don't want anybody thinking that it will do any more than that. At 9 o clock gain you can definitely hear similarities to a jcm 800. At about 4 o clock gain you get a chunky OD boosted sort of tone. And you can hear them clearly at very low volumes. Before the change it was bassy and not clear. Now its brighter and very British. If Marshall is your amp of choice then tweaking this amp to those tones for practice should be a snap.

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[Demanic]

Re: Marshall MG Upgrade

I bet it would sound on in a small room jam with bass and drums, as long as the base and drums could play at a moderate volume.

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[Demanic]

Re: Marshall MG Upgrade

^^
"sound good"

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[atf]

Re: Marshall MG Upgrade

^^
"sound good"

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Definitely, that's why I asked for an external jack mod, just to see how it sound with a 1x12 cab. If I had a 1912 Marshall cab with this as the head, theoretically i might get some convincing tones at practice levels.

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[Demanic]

Re: Marshall MG Upgrade

I would run it through my 1x12 cab with a C-Rex.

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[FuseG4]

Re: Marshall MG Upgrade

When my brother told me he wanted to learn to play, I got him a MG15 CDR combo.
Surprisingly useful right out of the box! If anything I'd want a warmer speaker, the only thing that I don't like about it for a small practice amp is that it has a little fizz and an artificial brittle/bright attack.

 

[atf]

Re: Marshall MG Upgrade

When my brother told me he wanted to learn to play, I got him a MG15 CDR combo.
Surprisingly useful right out of the box! If anything I'd want a warmer speaker, the only thing that I don't like about it for a small practice amp is that it has a little fizz and an artificial brittle/bright attack.

Change the speaker and its fixed. I was playing it post speaker change with a charvel Jackson j90c which is a ceramic pickup with slight high end, and I had to turn the treble UP to find a desirable balance. no fizz either

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[Aceman]

Re: Marshall MG Upgrade

IMO…

The little MG's are not bad at all for what they are. Pretty dang Marshally if you ask me (I know - you didn't).

The bigger ones are meh or worse. But i dig the little guys. And we all know that changing speakers can make a world of difference. Cool idea….