Best Crunch out of a JCM900?

[Axl H]

Hey.

I have this constant problem with my JCM900 4501, I cant play it high enough to crank it, so I have to rely on Preamp gain.

The problem is that, i either get too much or too little crunch tone.

Which settings no matter of volume will give me a nice JCM800-like crunch to some nice 80's Hard Rock like AC/DC and such?

Thanks.

 

[muttonchopsrule]

Re: Best Crunch out of a JCM900?

you gotta crank that ****!!!!

if you need to keep the volume down, i'd suggest buying an atteunater so you can crank up your amp and get your tone, but not wake up the neighbors.

 

[Axl H]

Re: Best Crunch out of a JCM900?

Well, the problem is that how do I crank it when i have to enable PreAmp gain?

I want that warm Marshall sound from the Poweramp part.

 

[Vasshu the humanoid typhoon]

Re: Best Crunch out of a JCM900?

Master all the way up, but it won't get that old school fatness and woody tone, it does not exist in a JCM900.
Much more crunchy and gainy.

 

[ErikH]

Re: Best Crunch out of a JCM900?

You put an attenuator between the amp and the speaker. You can do that with that amp. The speaker hooks up just like you would to the head version. The attenuator lets you crank the amp up but keep the overall volume coming out of the speaker down. Keep in mind though, too much attenuating will make it sound worse than using it without the attenuator and keeping the Master Volume down.

 

[Axl H]

Re: Best Crunch out of a JCM900?

Its 4501, it doesent have mastervolume, only one for each channel.

I dont know very much about valve amps, so i dunno that much about cranking.

I wont use a atteunator cost to much.

 

[ErikH]

Re: Best Crunch out of a JCM900?

The 4501 has a master volume, that's what the volumes on each channel are. It has preamp gain or volume, the tone stack (bass, mid, treble), presense, and each channel has a reverb and volume.

Cranking means turn the sucker up, crank the volume to 10. This also means your neighbors in the next zip code may here you and say something.

You can try Rid's suggestion. Crank the master volumes, and use the preamp gain/volume for overall volume control.

 

[Gearjoneser]

Re: Best Crunch out of a JCM900?

One trick I use to tame the volume on halfstacks is to use an FX unit that has a input/mix/output.....and put it in the FX loop. I sometimes use an Alesis Nanoverb I bought used for about $50. It's not the same as an attenuator, but it allows you to get more juice out of the preamp and power section, while adding a little reverb, and also controlling the overall volume with the Nanoverb output knob. There's a guy on Ebay selling a similar thing......basically a box with a pot that is inserted into the FX loop, giving you more control over the volume.

 

[ErikH]

Re: Best Crunch out of a JCM900?

One trick I use to tame the volume on halfstacks is to use an FX unit that has a input/mix/output.....and put it in the FX loop. I sometimes use an Alesis Nanoverb I bought used for about $50. It's not the same as an attenuator, but it allows you to get more juice out of the preamp and power section, while adding a little reverb, and also controlling the overall volume with the Nanoverb output knob. There's a guy on Ebay selling a similar thing......basically a box with a pot that is inserted into the FX loop, giving you more control over the volume.

Sorry, bro, but that little box does nothing when it comes to pushing the power tubes more, which is what he wants to do. All it does is bring down the signal at the end of the preamp before getting to the power amp. It's really good for taming sensitive volume controls like Fenders have where 1 is still freakin' loud but that's pretty much it. The only way to get good power amp saturation is to open up the master volume without anything else between it and the end of the preamp.

 

[Axl H]

Re: Best Crunch out of a JCM900?

Thanks guys, I'll try it next time i'm playin.

 

[Gearjoneser]

Re: Best Crunch out of a JCM900?

Sorry, bro, but that little box does nothing when it comes to pushing the power tubes more, which is what he wants to do. All it does is bring down the signal at the end of the preamp before getting to the power amp. It's really good for taming sensitive volume controls like Fenders have where 1 is still freakin' loud but that's pretty much it. The only way to get good power amp saturation is to open up the master volume without anything else between it and the end of the preamp.

I know that it's not the same thing as an attenuator, since it's not effecting the power tubes. I'm just saying it's a good way to be able to turn the amp up a little louder, and then choke off some of the volume with the FX unit. In any case, there's two kinds of amps....bedroom amps and gigging amps. For the price of an attenuator, it'd be wiser to go buy a small tube amp or modeling amp for home use.

 

[ErikH]

Re: Best Crunch out of a JCM900?

I know that it's not the same thing as an attenuator, since it's not effecting the power tubes. I'm just saying it's a good way to be able to turn the amp up a little louder, and then choke off some of the volume with the FX unit. In any case, there's two kinds of amps....bedroom amps and gigging amps. For the price of an attenuator, it'd be wiser to go buy a small tube amp or modeling amp for home use.

I made one of those volume boxes and tried it out on my 900. It was no different than turning the master volume down. If my amp had the touchy taper to it then it would be more useful but that's not the case with the 900's really.

 

[Zerberus]

Re: Best Crunch out of a JCM900?

Master all the way up, but it won't get that old school fatness and woody tone, it does not exist in a JCM900.
Much more crunchy and gainy.

+1, even the Lead Mk III (closest to an 800) lacks balls and teh throaty crunch ofn an 800, simply becasue of the design.....

the Hi Gain Dual Reverb´s on the other hand have an even harder time getting close..... they´re just plain not as dynamic and IMHO not nearly as "big" tonally...

The problem with pushing the powersection and lowering preamp gain: you´re still not really pushing the tubes, because now the premp is putting out such a weak signal that you´re still at bedroom level, even though the poweramp is just itchin to give you full blast.... Still won´t sound anywhere near as good as it will with the preamp level up as well.

In all seriousness (My opinion, of course): if you want the tone of an 800 at a bedroom level, then get an 800 and an attenuator... everything else is just pissing in the wind...

 

[greendy123]

Re: Best Crunch out of a JCM900?

Have you tried different pre-amp tubes yet? Using different tubes can give you different kinds of crunch. I find that the chinese 12AX7Cs warms up my distortion and gives it a thicker tone. Someone else might be able to help you fine tubes to try out. Speakers also make a big difference too. I'm not sure which speakers would give you that 80's hard rock tone, but I'm thinking v30's would work for that. You can get speakers that breakup quicker so you can get more of that poweramp distortion.

 

[the guy who invented fire]

Re: Best Crunch out of a JCM900?

Ok...I have to get invloved here...I see a lot of guys suggesting an attenuator,

An attenuator, NO MATTER HOW GOOD will not turn even a 20 watt amp into an apartment/bedroom amp much less a 100 watt, and an attenuator IS NOT a master volume and should not be used as one.

Seeing that you are looking for a "nice JCM800-like crunch" and you are using a 4501 I would say that first, you have the wrong amp...Im not saying it's a bad amp but it is the wrong amp for the tone you are looking for.

All that said mess around with the master volum and gain controls...you should be able to get lots of different shades of crunch and also don't forget that the 4501 has a half power switch...that will allow you to bring down the lever a little if you need to.

 

[greendy123]

Re: Best Crunch out of a JCM900?

All that said mess around with the master volum and gain controls...you should be able to get lots of different shades of crunch and also don't forget that the 4501 has a half power switch...that will allow you to bring down the lever a little if you need to.

I think the problem with using the half power switch is that the amp becomes totally different. IME the switch makes my tone warmer and sometimes I think it may muddy at times with my gain up.

 

[JeffB]

Re: Best Crunch out of a JCM900?

An attenuator, NO MATTER HOW GOOD will not turn even a 20 watt amp into an apartment/bedroom amp .

+1000.

Believe me, I've tried EVERYTHING. No workie.

The one thing tht is key is speaker push/breakup. No volume...(whether from the amp's vol controls or attentuated down) no speaker push. No speaker push, no classic Marshall tone/crunch. End of story.

If you want a cranked 800 type sound at low volumes invest in a modellling amp. It emulates the power section, pre-amp section, AND speaker push. It's not tubes, but will give ya a decent approximation. Another choice would be one of the better distortion boxes out there designed to simulate the sound of a Marshall stack (CM Plexitone, etc).

 

[WhoFan]

Re: Best Crunch out of a JCM900?

I've been reading thru this thread and it just reminds me why i have so many amps.... small amps for practice, louder tube combos for some gigs and jams, and tube stacks for big gigs...

If you like the 900 loud hang onto it for loud stuff.... and get something smaller and lighter on volume for other use..... I gave up years ago trying to get one amp to do every thing for me