JCM900 Boost?

P

pezking

New member
I've got a JCM900 100w Head, I play in a 6 piece band, and require a boost on my distortion channel for when I solo...

Ideally I just want to increase the volume of my distortion channel when I solo, as I like the tone, but there's no provision for it.

The only alternative I can think of is to buy a distortion pedal (which I've never liked compared to the Marshall) and use it on the clean channel.

Trouble with that is:

1. Costs money!
2. I would need to press two footswitches to get there
3. I like the sound of my amp currently.

Anyone got any ideas of what I could do? I tried out the TSL100 a few weeks ago, and I nearly bought it, but I thought my JCM900 sounded so much better!
 
I would suggest either an overdrive pedal or a clean boost pedal. They both do similar things, but an overdrive pedal generally adds a drive knob that lets you get more sensitivity and saturation without necessarily adding more distortion. Either way, they both boost your input signal and drive your amp harder without making big changes to your amp's distortion. I've never been a big fan of running a distortion/overdrive pedal through an amp's clean channel. I prefer to let the overdrive suppliment the amp's distortion.

Aside from that, I like to use my Boss CS3 compressor/sustainer pedal like a boost. Turn up the sustain and the level and I end up with a much more sensitive and louder signal that's perfect for soloing.
 
There's not much you CAN do to boost the output for a solo - you can use a clean boost or an OD pedal, true, but if you use one to get some extra juice going into the amp, and the preamp is already in distortion, all that's going to translate to is more gain, not more level.

If you're considering selling the amp for a TSL100, maybe give a Mesa Stiletto Series II a look? It's their take on the "Marshall" sound, and while it's more modern marshall than vintage marshalle (think Bogner Exctacy), a few of the modes will probably get you where you want to be.

It's only a two channel amp, but Mesa adds a second volume control for a "solo boost" for a lot of their amps. The idea is, you're playing through the same channel, but with the click of a button you add a variable amount of power amp clean boost, so that your preamp tone is the same and it's just like your master was a couple notches higher. They've been doing this on the Rectifiers for years, and it's pretty awesome - it'll allow you to dial in just enough extra volume for your solos to poke out of the mix, without killing anyone on stage the rest of the time. And, as it's really a second master volume control, that boost can go anywhere from a db or two up to pretty much full poweramp volume.

Alternately, on the cheap, try grabbing a footswitchable EQ. You won't be able to get any added volume out of it, really, but you may be able to "shape" the tone in such a way that it cuts through the mix better, and seems louder.

Likewise, on the "perceived output" tack, try using an OD for your [/i]rhythm[/i] tone, and bypass it for your lead. As the more saturated an amp is, the more the dynamics in your playing compress, it's possible to dial your amp gain and OD gain such that you have a thick, compressed, saturated rhythm tone, but when you bypass the OD the preamp gain alone is a lot less saturated so your dynamic response is more explosive. I actually tend to do this myself, I'll use a TS9 into my Recto for heavy rhythm (set as a clean boost), but generally I'll bypass it whenever I solo so the amp's naturally more "open" and "explosive" gain lets notes jump out a little more.
 
Put a clean boost in the effects loop.

I've got an MXR Micro Amp in mine and it works perfectly. It's like $70.
 
The effects loop is your friend here. I always used to cut my rythmm channel with an EQ pedal, and turn it off for solos. The advantage here was that by putting a little mid-cut on the pedal, I got a volume and mid boost for the solos. A smaller increase in volume, accompanied by a mid-boost, wil cut better than either alone, and won't increase the overall loudness in the room as much. Just adjust your sound with the EQ on, you should be able to keep your basic tone the same for rythmms.
 
Get an EQ pedal... lower the higher freqs and boost the mid-highs. You'll cut through with that real well.
 
ermghoti said:
The effects loop is your friend here. I always used to cut my rythmm channel with an EQ pedal, and turn it off for solos. The advantage here was that by putting a little mid-cut on the pedal, I got a volume and mid boost for the solos. A smaller increase in volume, accompanied by a mid-boost, wil cut better than either alone, and won't increase the overall loudness in the room as much. Just adjust your sound with the EQ on, you should be able to keep your basic tone the same for rythmms.
Click to expand...

+1 That really is the best way to do it.
 
I guess I tend to play with a slight crunch as my main tone. That leaves enough headroom that when I turn on my overdrive, it does give me more output volume. If you play with more distortion for your main rhythm tone, then yes all you'll get is more saturation and not more volume. But my TS9 adds more mids to my tone so even then, it cuts through more.
 
ermghoti said:
The effects loop is your friend here. I always used to cut my rythmm channel with an EQ pedal, and turn it off for solos. The advantage here was that by putting a little mid-cut on the pedal, I got a volume and mid boost for the solos. A smaller increase in volume, accompanied by a mid-boost, wil cut better than either alone, and won't increase the overall loudness in the room as much. Just adjust your sound with the EQ on, you should be able to keep your basic tone the same for rythmms.
Click to expand...

That does sound like a great idea actually.

I have two GEQ pedals around somewhere... Maybe I should resurrect them!

Thanks for the advice guys, I'll give it a go and see where I get.
 
OK So I tried it, and it almost provides the results I'm after!

Because it's a Boss GE6 I have (no overall level) I couldn't just boost/cut across the board, instead I had to boost or cut each frequency.

The good news is that it worked, and I now have a clear idea of what I need to do - either A) Build a clean boost pedal to put in the loop or B) Build a pedal with nothing more than a volume knob and a switch in!

Thanks for your help.
 
don't know if dod still makes them but i have a bi-fet preamp pedal that i used a lot in the past.it just has a volume and a tone knob.nice thing is i can eq it up to add a little more high or lows and either boost or reduce my volume.i ran it alongside a delay pedal,through the effects loop,and would kick them both on at the same time.
 
pezking said:
The good news is that it worked, and I now have a clear idea of what I need to do - either A) Build a clean boost pedal to put in the loop or B) Build a pedal with nothing more than a volume knob and a switch in!

Thanks for your help.
Click to expand...

Option B is what a clean boost pedal is: a pedal with just a gain knob and a switch. You could use any pedal with a gain/level knob and just turn down any other effects on the pedal. Most overdrive pedals can double as a clean boost since you can turn the drive down all the way and turn the level up.
 
Tadpui said:
Option B is what a clean boost pedal is: a pedal with just a gain knob and a switch. You could use any pedal with a gain/level knob and just turn down any other effects on the pedal. Most overdrive pedals can double as a clean boost since you can turn the drive down all the way and turn the level up.
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No my option B would be purely just a pot in series with the signal, merely providing attenuation.

I've instead decided to build a replica of the MXR Micro Amp. They sell for £75. I will build my replica for £18. Anyone want one made? :D
 
iownrocknroll said:
Whatever you do has to be in the effects loop for this amp otherwise distortion will increase.
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Bingo.

I hadn't realised until recently that the FX loop is between pre and power amp.

I need to service my amp at some point, the FX Loop level knob is a bit crackly.
 
pezking said:
Bingo.

I hadn't realised until recently that the FX loop is between pre and power amp.

I need to service my amp at some point, the FX Loop level knob is a bit crackly.
Click to expand...

Hey I have had success fixing crackly pots on amps with contact cleaner. Just spray (using the straw extension included with most quality brands) directing the stream into the inside of the pot while turning the knob on the outside. This usually clears up my issues. I'm a big fan of the jcm 900s, is yours a 4100? Does it have 5881 output tubes or is it a sl-x with the el-34s. I have played these many times and love the added gain, despite it coming from diode-clipping and NOT true successive gain stages (except for on the slx). Big fan I am
 
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owwmyfoot said:
Hey I have had success fixing crackly pots on amps with contact cleaner. Just spray (using the straw extension included with most quality brands) directing the stream into the inside of the pot while turning the knob on the outside. This usually clears up my issues. I'm a big fan of the jcm 900s, is yours a 4100? Does it have 5881 output tubes or is it a sl-x with the el-34s. I have played these many times and love the added gain, despite it coming from diode-clipping and NOT true successive gain stages (except for on the slx). Big fan I am
Click to expand...

Yeah that's something I keep meaning to sort out.

I think it's the 4100, but as for valves, I really don't know. I'll let you know when I clean that pot!
 
In one of my guitars I have a little clean boost pre amp that I built into it that has a 3 way toggle switch to set different gain levels...when I want to go into solo mode I just flick the switch and it adds a nice signal boost which also helps the overdrive by overdriveing the tubes more.....


Cheers
 
Minion said:
In one of my guitars I have a little clean boost pre amp that I built into it that has a 3 way toggle switch to set different gain levels...when I want to go into solo mode I just flick the switch and it adds a nice signal boost which also helps the overdrive by overdriveing the tubes more.....


Cheers
Click to expand...


Fair enough, but that wouldn't achieve what I'm after. I really need a boost in level not drive, plus it's not unusual for me to use 2 or 3 guitars during a set so I need a pedal solution :).

I'll post up the pics of my pedal build when I'm done.
 
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