Well I finally managed to have a proper practise thrash of my new JCM900, and I'm really disappointed overall. Its has very little Bass and the sound is incredible thin. Also (maybe because of the lack of low down chug) it doesn't seem to have a huge range of distortion. Considering it was on about 7 Master on full power mode it doesn't seem to really sing. I'm mainly annoyed because My old AVT100 combo with speaker upgrade and Metal Muff pedal absolutely killed it for metal. I'm using it with EMG's/ standard tuning and for metalcore type stuff, hardly Grindcore. Any suggestions on how I can beef the sound up? It has just had good quality valves in it. I was thinking that a brace of Celestion G12k-100 speakers would help (its the 4502 combo model) and I have a Boss GT-3 coming with EQ so I can tweak it that way. Does anyone have advice on maybe thickening up the Back of the combo as its only half-closed back. Maybe a thick sound-deadening material or can I close off the speakers somehow. The current wood section is pretty thin and only covers about 2/3rds of the opening. Any help appreciated. I'm guessing that all these early Death Metal bands that used it must have had the head version paired with a closed back cab...? Put it this way, I was totally upstaged by my mates MG100dfx and crappy cab when it came to anything more than widdly leads!

You want a boost through the thing. Grab yourself an overdrive and/or your Metal Muff and give it a nice dry/semi dirty boost into the distorted channel. Bam. Classic metal sound. A cheap suggestion for an OD pedal is a Digitech Bad Monkey, despite the dumb name it's supposed to be a kickass OD that sells for 40 bones, and many people prefer it over an Ibanez TS9 and shit.

New speakers won't make it sound substantially better for metal. Btw those speakers are in my Mode 4 cab and I don't like em too much, they have scooped mid response which means you won't hear any differences in the mids department unless you make HUGE adjustments with the mid knob. At least on my Engl Fireball.

It may be very useful in a 2x12 though, because they have good low end that open back combo's lack, and cut down on some of the mids that open back combos have too much of.

But I'd worry about the sound you're getting out of the preamp first. Drive it harder. And try boosting some bass within the FX loop.

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get a real booster, like a pedal thats designed to actually overdrive the tubes... i tried using my friend's big muff pi NY as a boost and it completely ate all of my picking dynamics, muddied the tone, and turned my grainy distortion into smoothed-out fluff... it was sad. I played with it for 2 hours looking for something good out of it and couldnt find shit. Sounds tres sexy on the clean channel... but none of my disto channels. The metal muff is a bit different, but i think all muffs use asymmetrical clipping circuits, so chords will get super muddy on high gain settings and start to sound like dischords. I dunno, try your muff, at least you dont have to go out and buy new shit to try stuff and i can guarantee that a real booster like a tubescreamer or a quality overdrive will kick your amp's ass into some decent distortion. I quote a man on this forum:

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hmm ok, well I've got a Boss Gt-3 on its way so I can add some Bass through the FX Loop with that but I'm wary of buying another pedal that I can't hear or use first, plus I've used a TS-9 on a Fender Blues Junior before and it did f**k all to the sound, and I need a hefty jump in gain. Annoyingly I don't actually have a Metal Muff anymore but that thing sounded way better than the JCM OD channel, bullshit that pedals don't sound as good as real tubes, well for metal anyway. I feel really pissed off as so many times I've read that valves are the way to go and that the JCM is perfect for 90's metal but it doesn't even come close. I'd sell it and just buy my Metal Muff back with my AVT again but I've piled too much money into it now that I feel I have to sort it. Will the Speaker choice make a difference? And can I run the Amp as a single speaker combo for a test as I have a G12k-100 already, but its 8ohm so its needs to be run on its own. Thanks for your help and please excuse my internet rants, I'm just unbelievably annoyed at the amount of money I'm spending to get a half-decent sound.

get a real booster, like a pedal thats designed to actually overdrive the tubes... i tried using my friend's big muff pi NY as a boost and it completely ate all of my picking dynamics, muddied the tone, and turned my grainy distortion into smoothed-out fluff... it was sad. I played with it for 2 hours looking for something good out of it and couldnt find shit. Sounds tres sexy on the clean channel... but none of my disto channels. The metal muff is a bit different, but i think all muffs use asymmetrical clipping circuits, so chords will get super muddy on high gain settings and start to sound like dischords. I dunno, try your muff, at least you dont have to go out and buy new shit to try stuff and i can guarantee that a real booster like a tubescreamer or a quality overdrive will kick your amp's ass into some decent distortion. I quote a man on this forum:

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Well I'll take that into consideration. But....and this sounds sacriligious but if I decided to use the Metal Muff as my distortion running through the Clean Channel (God what a waste...) will I still retain the picking dynamics and clarity integral to the JCM? I just have no ideas about Boosters and I don't have time or a place to try stuff out and as much as I take advice from the internet I'm not willing to spend anymore money on faith. Like I said I thought the Ibanez TS-9 was crap. So I'd rather stick with things I know I like, like the MM and the speaker choice

Fuck TS9's then. Grab yourself a Digitech Bad Monkey(cheap analog OD pedal that has 9.5 average reviews on HC, from like 60 fuckin reviews). Many prefer it over the TS9.

If you still can't get the sound you want out of it then sell the thing man. And pick up something like an Engl Screamer or Thunder combo.

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Thanks for putting me on to the Bad Monkey, I may give this a go first with the speaker upgrade and see whether I can get the amp any meatier sounding. Also can anyone recommend a wood/foam board that I can attach to the inside of the rear particleboard, maybe to 'insulate' the speakers a bit more. Theres barely 1/4 inch of wood between the speakers and air, I'm thinking this is part of the problem?

Like I said the speaker isn't going to make it sound like it has more distortion, forget about it, I'd just suggest using the BM first just to be safe in case you screw up during the speaker swap, cuz you would be risking your amp's health unnecessarily when a speaker swap is not going to make any significant difference in tone.

Particle board construction? That sucks. Yeah, there's your loss of lowend there. Might as well build a cabinet for it out of solid wood or plywood, or nail some wood to the back perhaps. Foam won't do much to a low grade material cabinet.

Damn I would expect particle board on an MG or valvestate combo, but on a JCM900? Marshall sure knows how to cut corners, that's lame.

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Well I say particle board but I don't know, put it this way it feels cheap and its half as thick as the rear board on my AVT, seriously its like matchwood. Hopefully my Grandad (!) can knock me up a big fat piece of wood to replace it, there's certainly room. What wood would be recommended? On the Speaker front, I don't want the change to add gain but to beef up the low end and bass response ala the G12k-100 with its big low-end. I've done a speaker swop before and Celestion do a nice section all about swapping a 2x12's speakers including impedence etc. Plus the JCM has an impedence selector. Bad Monkey sounds good, I'll pick one up in the next day or two.

I think the simple problem is that Marshalls sound thin, period. Thats the way they are. Some serious modding would have to be done to really get great tones. You can start by changing the tubes, that will make a huge difference. Get some decent preamp tubes atleast, thats where most of the distortion comes from anyway.

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Well Marshall's don't have a massive lowend like many other high gain amps do, but they're by no means thin unless you're running em into a shite cab or usine crappy tubes. If you toss that combo into any good closed back cabinet you'd get fuller sound.

But this has nothing to do with the sound being meaty or not. He's not getting the distorted grind he wanted out of the thing.

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couldn't you sell it? im sure since itis a marshall it would sell for quite a bit

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I've only just bought it and put new EHX tubes in it, I really don't want to have to sell it as I won't get the money back on it. There's very little out there in my price range apart from the ENGL combo's Soeru mentioned but they are all 1x12 and I really want a 2x12 for gigging. I guess I'll try out the couple of mods I mentioned and then see what its like.

A 1x12 50W tube combo is more than enough for gigging man.

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Put an EQ in the loop (ge-7, mxr, etc..) then boost the front. Should be all the lows and grind you'll need.

Well I've got a Boss GT-3 coming that I'll be putting through the loop, that has an EQ with up to +20db of boost on the low frequencies. I've put in an order for a Vintage 30 to pair with my G12k-100 and I've also just picked up a Digitech Bad Monkey to boost the Dirty channel. Plus I'll be getting a big 1/2 inch thick piece of of plywood made up to replace that piece o'shit that counts as the rear sounding board sometime next week. I'll let you all know how it turns out. Thanks for all your help, esp. Soeru for putting me on to the Bad Monkey.

Damn sounds like a lot of work, I really hope you get the sound you want out of it man. You're welcome.

Btw try epoxing the inner corners of the cabinet, and make the enclosure as airtight as possible for added lowend. Then you should try sound insulation foam inside.

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Yeah I'm definitely going to get some insulation foam at some point, I'll read up on the best way to go about it. I'm not sure whether I'll truly be able to make it fully closed back, just because its all fairly compact in there and I don't really want to mess around with the tubes. Its actually got very little cabinet at all, as the back is virtually non-existent and the sides are half missing because it has the huge plastic grab handles instead. Oh well, I'm sure theres a great sounding amp somewhere inside it, just gotta find it!

Ok, installed my new speakers and boosted the amp via a Digitech Bad Monkey, hot damn what a difference!!! The pedal just adds loads of transparent gain and fat sustain, fucking ace. I can't wait to get it beyond bedroom levels, roll on band practise! Thanks again to everyone for their help, my tone is finally sorted!

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You need to set the EQ right, I normally have my bass on full, mids on 1 and treble never above 5.5
Your enemy is the treble, this amp has way too much. Reduce the treble and mids to make the bass stand out. It also helps A LOT if you have an EQ pedal like a Boss GE-7. This EQ pedal is fuckin useful lol, it also adds gain. Again, I have a clip on youtube called ''Jackson Warrior with GE-7 Equalizer''.

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Ok well thanks for the help..... albeit about 7 months too late. Seriously man stop ressurecting old threads!

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