Bare Knuckle Pickups Forum

Forum Ringside => Guitars, Amps and Effects => Topic started by: richard on July 17, 2013, 07:01:36 PM

Title: JCM 900 surprise
Post by: richard on July 17, 2013, 07:01:36 PM
Rehearsed last night. Usually I take my Cornford Roadhouse combo with me but last night I had to use the studio's backline. They have a lot of amps but there's always something in the room which you can change if you want. Last time I didn't take my own amp I used an Orange half stack which I hated.

Last night there was a JCM900 Dual Reverb half stack. I remember borrowing one of the dual MV 900 combos many years ago and finding it okay if rather unremarkable. I know that a lot of people consider the 900 Dual Reverb to be one of the worst amps Marshall produced.

Anyway - I had a go at the clean channel to see if I could get a usable crunch sound for rhythm. Horrible, dull, lifeless. So I switched to the lead channel with all EQ at noon, gain and master half way up, presence at zero. Ear splitting nasty treble. So I turned the treble all the way off. Better, but muddy. So I brought the presence up to 4pm. Now I was getting somewhere. Pushed the mid and bass up a little.

Now I'm getting an awesome crunch sound. My Firebird Studio with RYs sounded wonderful - absolutely nailed the classic rock crunch sound. Some lovely grit. As I've used up the lead channel for my rhythm sound I plugged in the old trusty Boss OD3 for a little more gain for solos. Excellent sound. The RYs sounded absolutely amazing through this set up. Cleaned up really well and the neck pick sounded wonderful too.

This amp really surprised me. It's way too toppy but with the treble off and the presence low it sounds incredible. I don't know if it was the 5881 or EL34 model. Didn't have my reading glasses so had the usual problem of being almost unable to see the settings. Marshall - please use chicken heads.

These amps usually go pretty cheap. Might try and pick on up if I get the chance as I need a back up.
Title: Re: JCM 900 surprise
Post by: gwEm on July 18, 2013, 10:30:06 AM
people often diss the JCM900 dual reverb.

i wouldn't say its my favourite amp, but i agree it sounds quite good. whenever i've needed to use one i've always been pleasantly surprised.

at the price i'd probably prefer a DSL50 if i was in the market for that sort of amp.
Title: Re: JCM 900 surprise
Post by: richard on July 18, 2013, 05:25:30 PM
I wouldn't mind spending some time with a DSL. I used one at a jam once and it sounded horrible but I didn't get much time to figure it out.
Title: Re: JCM 900 surprise
Post by: Brow on July 18, 2013, 05:29:25 PM
I wouldn't mind spending some time with a DSL. I used one at a jam once and it sounded horrible but I didn't get much time to figure it out.

I'm a fan of the DSL50s myself, I almost sold my JCM800 split channel for 1.

If you use them on the clean channel with the crunch mode on, they take OD pedals really well. Its how Gary Moore used his and I really liked his tone with a Bad Monkey as a boost with these amps.
Title: Re: JCM 900 surprise
Post by: jpfamps on July 19, 2013, 07:38:22 PM
The JCM900 certainly isn't my favourite amp, but is starting to look a bit of a bargain as they seem to be fetching between between £350-500 second hand.

The clean sound is passable on the 5881 version.

The build quality is much better than the DSL50 (we've not set the bar very high here).

All the pre-2005 DSL and TSLs have a problem with their PCBs that manifests itself in the amp over heating.

The remedy for this is a PCB change (not cheap), although there are some punters on the internet who have effected a repair by dremelling away substantial parts of the PCB!

If you are unlucky the over heating can take out one of the transformers.

Last one I repaired need a new mains transformer and PCB, and the bill was around £200 (it also needed new valves, but the customer had some spares which save £50 off the final total).

Even if you like the sound of the DSL/TSL (I don't and can't imagine why anyone would) I can't really recommend them in terms of build quality.



Title: Re: JCM 900 surprise
Post by: Dmoney on July 19, 2013, 07:50:09 PM
The split channel 800's are nice, but the trick is to forget the clean channel totally, and turn the overdrive channel volume up to 9 or 10, and then use the master volume to set the overall volume. MUCH better tone.

the DSL head is Marshall's biggest selling head I think. I'm not sure if I've played one or not now that I think about it. Had mates with them and TSL's. My friends with TSL 100watt heads had more issues than my mates with DSL's.
Title: Re: JCM 900 surprise
Post by: richard on July 19, 2013, 08:12:08 PM
I've never used a TSL and never been tempted to try one. When they first appeared I saw quite a few guys using them at my local pub and I thought that Marshall had reached an all time low in tone. They sounded solid state to me and not unlike an early model Peavey Bandit.

I saw the Marshall demo of the latest multi mode thing wotsitsname and thought it sounded even worse. I'm curious about the new DSL but from what I've heard they suffer the same excess top end as the 900. My Roadhouse gets great tones with bass, mid and treble all hovering around the noon mark which, to me, is how it should be. If I had the cash in hand I'd buy another of the few remaining RH combos because it looks like Cornford is dead.
Title: Re: JCM 900 surprise
Post by: Dmoney on July 19, 2013, 09:06:31 PM
you could always get someone to reverse it and build you a copy
not that much stuff inside it.
(http://i527.photobucket.com/albums/cc359/adr1anos/IMG_5618a.jpg)

Title: Re: JCM 900 surprise
Post by: BigB on July 19, 2013, 09:52:07 PM
The JCM900 certainly isn't my favourite amp, but is starting to look a bit of a bargain as they seem to be fetching between between £350-500 second hand.

The clean sound is passable on the 5881 version.

The clean / crunch tone is more than passable on the EL34 version - at least with an open cab, and it sounds way better with the master volume set above 10 o'clock but that already way too loud. FWIW I just don't understand how some of you guys manage to use anything louder than a 20/30 watters ? :scratch:

Title: Re: JCM 900 surprise
Post by: jpfamps on July 19, 2013, 10:26:25 PM
you could always get someone to reverse it and build you a copy
not that much stuff inside it.
(http://i527.photobucket.com/albums/cc359/adr1anos/IMG_5618a.jpg)

The construction details look suspiciously similar to Ornage amps.......
Title: Re: JCM 900 surprise
Post by: JJretroTONEGOD on July 20, 2013, 12:11:55 AM
I've never used a TSL and never been tempted to try one. When they first appeared I saw quite a few guys using them at my local pub and I thought that Marshall had reached an all time low in tone. They sounded solid state to me and not unlike an early model Peavey Bandit.

I saw the Marshall demo of the latest multi mode thing wotsitsname and thought it sounded even worse. I'm curious about the new DSL but from what I've heard they suffer the same excess top end as the 900. My Roadhouse gets great tones with bass, mid and treble all hovering around the noon mark which, to me, is how it should be. If I had the cash in hand I'd buy another of the few remaining RH combos because it looks like Cornford is dead.

whatever you do never get a TSL they are terrible amps, when I owned one I wanted it to set on fire and explode or blow up, the DSL JCM2000 amps were much better sounding.
Title: Re: JCM 900 surprise
Post by: Dmoney on July 20, 2013, 08:20:08 AM
The construction details look suspiciously similar to Ornage amps.......

That is something I thought too. Great minds think alike.
Title: Re: JCM 900 surprise
Post by: richard on July 20, 2013, 09:35:48 AM
Well they definitely don't SOUND like Orange amps. I used an Orange half stack recently and I was expecting to like it having read so many favourable comments but I thought it was terrible. The gain sounded more like a fuzz box to me. I used a Rocker 30 combo at a jam once and it was like playing through a packet of cornflakes, just a nasty little box. I don't understand combos where the speaker is crammed into the smallest possible enclosure. The RH combo has a huge open backed cab and it sounds big and three dimensional. Blues Juniors - they're just as bad as the little Orange amps.
Title: Re: JCM 900 surprise
Post by: Dmoney on July 20, 2013, 10:00:01 AM

The construction just looks a bit like a Tiny Terror, although the Tiny Terrors now have holes in the PCB placed strategically around the valves to help disperse heat. They both have ground planes on the PCB around the input jacks, they both have the filament wiring on push-on connectors and not as traces on the PCB. The roadhouse is more tidy.

(http://img.photobucket.com/albums/v609/Zeriton2/TTinsidesflash.jpg)

Here is a Rocker 30. Also with a ground plane on the pcb around the input jack and the first couple of preamp stages. This looks like it has the heater voltage on the underside of the pcb but the valve orientation keeps the preamp components away from those traces while the addition of the ground plane might help reduce noise from the heater traces and possibly the high voltage by acting as a shield early in the preamp. It even looks like they use similar fonts and graphics on the silkscreen layer.

(http://www.ajaudio.co.uk/O8.jpg)

Nothing badly wrong with any of these amps. They are all pretty well laid out I think and designed to be easy to produce.

As for the tone, Orange isn't really for me either. I wouldn't say the small enclosure thing is typical with them though.
Title: Re: JCM 900 surprise
Post by: richard on July 20, 2013, 12:26:02 PM
Our singer's birthday last night. Some friends of ours played the bulk of the night but we used their gear to play half a dozen songs. So I got to use a Marshall SLX half stack. I decided to set it up pretty much how I did the 900 - take the treble and presence right down and bring a bit of it back to hit the sweet spot. Very different sounding amp to the 900, it seems to be aimed at guys that like a scoop in the mids which personally I don't. I was playing a bit louder than I usually do as it was a large pub.

Got an okay sound and went into our first song and the sound disappeared completely. It did not cut it in the mix at all mainly because of the weak mids. My mate Dave, owner of the amp, tweaked it while I was playing and got it sounding better but he also had to turn it up a lot more to get it to cut through. As far as I know the SLX is all tube whereas the 900 uses diodes in the gain circuit but I much preferred the sound of the 900. The 900 had much stronger mids and a lovely grainy quality to the overdrive that was absent in the SLX.

Still, it's fun to try different gear. 
Title: Re: JCM 900 surprise
Post by: Telerocker on July 20, 2013, 01:00:24 PM
Blues Juniors - they're just as bad as the little Orange amps.

Unless you hook them up to a 2x12 cab. I agree a lot of those tiny enclosures sound boxy.
Title: Re: JCM 900 surprise
Post by: Dmoney on July 20, 2013, 01:25:40 PM
Our singer's birthday last night. Some friends of ours played the bulk of the night but we used their gear to play half a dozen songs. So I got to use a Marshall SLX half stack. I decided to set it up pretty much how I did the 900 - take the treble and presence right down and bring a bit of it back to hit the sweet spot. Very different sounding amp to the 900, it seems to be aimed at guys that like a scoop in the mids which personally I don't. I was playing a bit louder than I usually do as it was a large pub.

Got an okay sound and went into our first song and the sound disappeared completely. It did not cut it in the mix at all mainly because of the weak mids. My mate Dave, owner of the amp, tweaked it while I was playing and got it sounding better but he also had to turn it up a lot more to get it to cut through. As far as I know the SLX is all tube whereas the 900 uses diodes in the gain circuit but I much preferred the sound of the 900. The 900 had much stronger mids and a lovely grainy quality to the overdrive that was absent in the SLX.

Still, it's fun to try different gear.

The SL-X is mostly valve and doesn't use diode clipping, however given that it has a preamp topology like many great high gain amps it doesn't sound the best. There are some odd choices in there for frequency filtering and the tone stack does next to nothing to help you out. It's not a tone stack with typical marshall values around it. Also, the master volume switching is done using solid state, so after the tone controls (which are late in the preamp) the signal needs to be dropped so it doesn't fry the opamps, then later on its switching opamps that drive the phase inverter, which is valve again. The don't sound the best, but their rep is that they are the best of the 900's. Probably easier to work on them and mod them than the rest of the 900's too.

The JCM900 4100 dual reverb is a hybrid amp. It's not just that the clipping is done with diodes (like the friedman/jose/cameron mods) its that most of the preamp is solid state. The tone controls that you can tweak are driven by a valve gain stage and cathode follower (one whole valve) the tonal impact of which is debatable, by which i mean may be it would be better to have the valve at the first stage and the tone stack driven by opamps, but there are a couple of opamp gain stages your signal goes through before it gets to that point. There is a single valve gain stage which give you a "presence" control in the preamp (I think), and the other valve is the phase inverter. The first couple of gain stages are opamps, the FX loop send and return stages are opamps, the reverb driver and recovery stages are opamps and the master vol switching is opamp.


 
Title: Re: JCM 900 surprise
Post by: Alex on July 21, 2013, 02:27:54 PM
The two-channel JCM900s have some clear tonal limitations due to their preamp design, which is why they are not very highly coveted. I played one for years (as I couldn't afford a new amp) and you can get some decent sounds out of them, but once I got a 5150 there was no need to ever use the JCM900 again, except maybe for some cleans.

If I had to rate the amp on a scale of 1 to 10, I'd give the EL34 version a 6 and the 6L6 version a 5. Not great, but not terrible.