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Change Marshall MG100DFX sound

windavenger

Member
Messages
9
Hi, I got a Marshall MG100DFX 1x12 Combo about 1 year~
And now....I Still feel the sound isnt smooth ....
Cold like Stone, so I wanna upgrade something to the amp~

I have some questions about it~~
1) What is the speaker in MG100DFX?? Celestion??

2) Maybe I will upgrade the speaker first...
Want it Warm, Smooth, Vintage~
What kind of speaker is great?? Celestion Vintage 30, Greenback or
G12H?? or others??

3) If the problem isnt on the speaker...is preamp or poweramp....
I think is not easy to slove....

Tell me about your experiences , and give me some opinions....
Thanks a lot !!
Let's Rock !!:RoCkIn
 

John Phillips

Member
Messages
13,038
Hi, I got a Marshall MG100DFX 1x12 Combo about 1 year~
And now....I Still feel the sound isnt smooth ....
Cold like Stone, so I wanna upgrade something to the amp~

I have some questions about it~~
1) What is the speaker in MG100DFX?? Celestion??
Eminence. I don't know the exact model equivalent - it's not labeled - but I doubt it's anything good, since the amp sounds far better through a good external cabinet.

2) Maybe I will upgrade the speaker first...
Want it Warm, Smooth, Vintage~
What kind of speaker is great?? Celestion Vintage 30, Greenback or
G12H?? or others??
I would replace it with a Celestion G12K-100. Marshall + Celestion = Just Right. ;)

You need a minimum of a 100W speaker to handle the power of the amp really, so a V30 isn't enough, let alone a Greenback. You might just get away with a Classic Lead 80 - if you use an 8-ohm speaker, the amp won't quite deliver the full 100W... the stock speaker is 4-ohm, so at 8 ohms you'll probably get about 70W.

Also, if you do replace the speaker with an 8-ohm, you could drill the back panel and fit the extra speaker jack so you could run an extension cab at the same time (which you can't do with the stock 4-ohm speaker). It is fairly thick steel though, so make sure you have the right tools to drill a hole like that cleanly and accurately.

3) If the problem isnt on the speaker...is preamp or poweramp....
I think is not easy to slove....

Tell me about your experiences , and give me some opinions...
Part of the problem is the power amp. It doesn't just sound crap, it's unreliable too. After replacing more than a few of them - and once getting the same amp back a second time with the same fault - I decided to do this:

Before -



After -



I didn't realise quite how bad the stock one was until I did this. Afterwards, not only did I run the amp at absolutely full distorted power for an hour without it blowing up (something I doubt could have been done with the original power module even if working 'properly'), the amp sounded far better too.

That's a Velleman 100W Mosfet power module kit BTW.

Yes, it's a fair amount of work - whether it's worth it or not depends on whether you think you want to keep the amp and whether you can get sounds you like out of it already. Don't do it if you don't really like the amp, it doesn't change the fundamental sound, it just improves the tone (if you see the difference :)).

You can see the place on the rear PCB where the second speaker jack fits too.
 

windavenger

Member
Messages
9
I think I will replace a speaker first...
So I must replace a speaker which is about 70W (8-ohm), right ??

"Velleman 100W Mosfet power module kit"
If replace speaker doesnt change too much...
I think I will buy the kit :D
Where can I buy it ??

Change another amp might be right...
But I wanna make it different that I can do myself
DIY Spirit !! :nono

Thank you, I didnt have much knowledge about amp and speaker~~
 

bonchie123

Silver Supporting Member
Messages
1,155
Honestly, for what it'll cost you to upgrade the speaker, you could sell the MG for a few hundred bucks used, put a little money on top of it, and buy a cheaper tube amp that will sound alot better.

But thats just my opinion. Upgrading an MG just seems a little pointless to me. I'm no expert though (although I have played an MG).

What kind of music do you play?
 

windavenger

Member
Messages
9
Honestly, for what it'll cost you to upgrade the speaker, you could sell the MG for a few hundred bucks used, put a little money on top of it, and buy a cheaper tube amp that will sound alot better.

But thats just my opinion. Upgrading an MG just seems a little pointless to me. I'm no expert though (although I have played an MG).

What kind of music do you play?
You are right~ Change a tube amp might better to me~
But the amp is not my own...
It's stuff of my school
I cant sell it, But I can modify it... Haha~

Many students playing it at school...
I just a manager of the club

They play music like Radiohead, Led Zeppelin, Brain Setzer...etc
Many Music type...
But we like vintage sound at the same~:D
 

John Phillips

Member
Messages
13,038
I think I will replace a speaker first...
So I must replace a speaker which is about 70W (8-ohm), right ?
You need at least 80W at 8 ohms or 100W at 4 ohms. (4-ohm speakers are quite hard to get though.) 100W at 8 ohms would be better.

"Velleman 100W Mosfet power module kit"
If replace speaker doesnt change too much...
I think I will buy the kit :D
Where can I buy it ??
Maplin Electronics if you're in the UK - no idea where (or if) if you're not, but there will most likely be equivalents.

But don't do it unless you've already changed the speaker and it doesn't give you what you want - and it's maybe not a job you can do yourself anyway unless you're experienced with this sort of work.
 

windavenger

Member
Messages
9
You need at least 80W at 8 ohms or 100W at 4 ohms. (4-ohm speakers are quite hard to get though.) 100W at 8 ohms would be better.

Maplin Electronics if you're in the UK - no idea where (or if) if you're not, but there will most likely be equivalents.

But don't do it unless you've already changed the speaker and it doesn't give you what you want - and it's maybe not a job you can do yourself anyway unless you're experienced with this sort of work.
OK~few speakers I can choose...
G12K-100、Classic Lead-80、G-12 Century(Expensive...)、G12T-75(←may not enough) at 8-ohm

Yup~I never do it before~
Anyway, I will change the speaker~
And I will share the experience soon~

Thank you, John P :dude
 

John Phillips

Member
Messages
13,038
OK~few speakers I can choose...
G12K-100、Classic Lead-80、G-12 Century(Expensive...)、G12T-75(←may not enough) at 8-ohm
I would probably avoid the 75. It might just take the power, but it's voicing is too close to that of the amp (lacking mids, with a flappy bass and buzzy treble) and it will make the amp sound far too scooped and undefined.

The G12K-100 would be my first choice because its tone (very even and smooth) will improve the amp and it will easily take the power without risk.
 




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