Tips for dialing in a JCM 800?

[Mr.Grumpy]

Our band's bass player (we practice at his house) is going to let me borrow his JCM 800 for practice. He has the matching 4x12 slant cab for it too. Great, right? Yeah, but I'm used to playing through my hyper-clean, Fender flavored Music Man HD-212. All my dirt is from pedals: a EHX Soul Food, a BRAT modded to RAT specs, and a homemade silicon fuzz. I do the standard 3 tone type setup: a slightly dirty rhythm tone, a crunchy rhythm tone (power chords) and a 'soaring' sustaining lead tone, which is either the fuzz, or the Soul Food boosting the RAT. I also have a tuner, passive volume pedal, a chorus, trem and delay pedals on my pedalboard, but the delay the's only one of those that used frequently.

 

Last week the other guitarist played through this rig, and he didn't sound so good. His volume was low, his sound was trebly, and the rig buzzed horribly when he engaged his OD pedals. I glanced at the amp settings after practice, bass was on 8, treble at 4 or 5. I don't remember where the mids or presence were set, but surprised how thin it sounded for a 4 x 12 closed back cab. I'm hoping I can get this to work for me so I can take my other amp home and not have to lug my amp back and forth or leave at his place taking up room.

[AJ6stringsting]

The JCM 800 will only need an overdrive, the fuzz or any other heavy distortion will come out so heavy, that the dynamics will be barried.

You may need to use a noise gate to tackle the excess noise in the effects loop and get a graphic or parametric Eq to get you there, sonicly.

You may have to spend time with that amp, to understand it.

[1001gear]

Marshall preamps are voiced to cut through loud rock. For that matter they are loud rock. The tone will not fatten up until you lean on the power stage, transformer and cabinet regardless of the front panel settings. (not entirely true - sue me)

IOW real loud.

[t_e_l_e]

jcm800 is not jcm800

 

there is a 100W, a 50W, the early ones have only one volume control, you need to turn it up to get the rawk, then they introduced the master volume, where you can get nice gain from the gain knob, but reduce the earbleeding with the master volume.

 

then some jcm 800 have a tone cap, some don't, some had it stock but it was removed.

 

if i'm right, the tone cap is a small ceramic capacitor on the back of the gain pot, it lets mid-high and high frequencies through the first gain stage and dims them less, which result in a more trebly sound, especially when played with less gain and low volume.

 

for some this might be favorable, for others it has too much treble. a lot of metal fans remove this cap by clipping it out, to get less treble and tell everybody the it has afterwards more bass and balls.

 

what kind of jcm800 does your bass player have? with/without tone cap? at which volume do you play?

 

i love a jcm800 at low gain settings with a booster in front to add some crunch.

 

so dial in a base sound without any pedals which you like and has the adequate volume and than expect to change all knobs on all of your efx pedals, so the pedals sounds great with the base sound of your jcm 800

 

its very unlikely that you can use any of the settings of the pedals you use with the musicman on the jcm800, you can use them but the will definitely not sound the same and i doubt you will like the results...

[Mr.Grumpy]

...

what kind of jcm800 does your bass player have? with/without tone cap? at which volume do you play?

 

Dang it, I don't know. I think it's a 50 watter, I vaguely remember looking in the back and seeing only two power tubes. I read up a little on the JCM 800, and was aware there's an 'original' version made in the 80's and the re-issue which also has an effects loop. It DOES have a master volume, definitely. I counted 6 knobs: bass, mids, treble, prescence, gain, and master volume. How loud? Our band's volume is enough that my ears ring the rest of the night. Two guitars, bass, drums, vocals in a converted garage. Pretty much a two rhythm guitar band and the bass player typically plays with some distortion too. I consciously try to play with LESS distortion than my co-horts in an attempt to keep the sound "tighter".

 

I'm going to try to get to practice a little early and mess around with it.

 

if i'm right, the tone cap is a small ceramic capacitor on the back of the gain pot, it lets mid-high and high frequencies through the first gain stage and dims them less, which result in a more trebly sound, especially when played with less gain and low volume.

 

for some this might be favorable, for others it has too much treble. a lot of metal fans remove this cap by clipping it out, to get less treble and tell everybody the it has afterwards more bass and balls.

My Music Man has something very similar, basically a treble bleed cap on the gain pot, but thankfully on the MusicMan amp it's connected to the "bright" switch and can be turned off, because when it's on it gets piercing treble.

 

The fun thing about having a pedalboard is that it's pretty easy to swap out pedals, so I'll take off the RAT, put a tubescreamer in it's place, and maybe throw a graphic EQ pedal on there too.

 

 

[Mikeo]

I have a JMC800 2x12 50 watt combo, that runs 2-6550's power tubes. I purchased it new in 1983. The 6550 power section was a USA import thing, and might have less gain, but I believe is louder than the made for UK version EL 34/KTT77 ( which are different in there own right).

 

I like the amp for what it is. I'm not big on the clean sound at all and I don't drive it with any OD box. What I do is crank it up to 7-8 (2-3 o'clock) on the preamp dial and go from there. Adjust master volume as needed. So it's not a super high gain tone, but has a nice crunch to it.With more gain it will go into singing sustain and then into a nice feedback.

 

 

 

AC/DC, Bad Company, Early 80's Billy Squire, maybe a little ZZ Top, and other classics hard rockers, it's pretty much there. Plug and play. Pissing off your neighbors, your mom or your roommates, is about the perfect volume for it.

 

It was made to do one thing:rawk:, and what it does it does well.

 

You need to decide if hauling the thing around is worth it. I stopped gigging with it a long time ago, and started using a Fender amps with an OD pedal and effects, or sometimes a Mesa amp.

 

Who knows what Mick Ralphs is using for amps here, but you'll get the idea.

[video=youtube;WmJrisOBzJ8]

 

[WRGKMC]

Setting are going to be different depending on the speakers being used.

 

As far as a Marshall matching a Fender or vice versa, its not going to happen. The tone stack is in a different place in the signal chain and the way the amps gain up with that tone stack is very different. I run a Fender and a Marshall side by side recording and the Marshall produces a different upper mid curve and more highs. The two amps work together well "exactly because they don't" produce the same responses.

 

If you have two amps producing the same responses, one will always mash the other as they fight for that frequency range. If you use a Marshall and Fender, the Marshall will always dominate the upper mids and treble if its cranked. What you have to do is determine which player is suitable using those frequencies based on your musical arrangements.

 

You also have the guitars to consider. If someone plugs into a Marshall with single coils and plugs humbuckers into the Fender, the range between the two amps is going to be much wider then using singles in the Fender and HB's on the Marshall.

 

In all cases you'll need to get used to playing along to a Marshall. You may think it sounds awful at first, as though there's a wedge blocking your own sound, but get out in front of that audience and it can actually produce a great balance. You just have to get used to someone else dominating that part of the audio spectrum and refine the best tones you can get within your own. You'll loose some top end but you'll be able to produce warm chords and lower mids that Marshall cant touch. No matter how much bass is boosted or treble attenuated, the marshal wont mask your frequencies or vics versa. Its just he will be in those upper mids your amp cant produce well.

 

Heres the response curves of the two.

 

 

 

 

[WRGKMC]

Here's the rest. Don't know what happened to my Fender bass response curve went but you get the idea. These curves are different and instead of trying to make them sound similar, focus on their differences. You're always going to favor your own tones over others. Just don't mistake playing skills with frequency response. The two are not the same.

 

 

 

 

 

 

 

 

[codecontra]

These amps usually shine when boosted with something like a Boss SD-1 with the drive all the way down and the level all the way up (and tone in the middle). That's pretty much the gold standard with these amps and really can make a massive improvement in tone quality.

 

Of course, he could have older tubes or the amp may need some work/tweaking. It's probably approaching 30 years old so hard to tell what he's got going on inside. If it is in good working order, you should be able to get a gig worthy sound out of it. The JCM 800 has pretty much been the go to rock amp since it was first introduced.