How do I Beef up my amp?

Re: How do I Beef up my amp?

Could be bad tubes or it could be a cheap output transformer. It could also be a poorly constructed circuit. My JTM-45 clone built by Scott_F will outshake a Peavey XXX at full bore through the same or different cabs. It has a metric ton of bass.
 
Re: How do I Beef up my amp?

Try tubes, if that isn't it, then try an EQ on your amp, to add the lower thumping frequencies, and if that dosen't work then get an amp more suited for you...
 
Re: How do I Beef up my amp?

Enjoy both amps for the character they impart. Its good to have different amps for both recording and working with different bands etc.
If you like the 800 - just use it. JTM's are not better or worse - just different. No need to modify it, if you already have another amp that does what you are after.
Keep playing the JTM tho, because it may just be the right voice for a different style of playing that perhaps you have not yet explored.
 
Re: How do I Beef up my amp?

Ok, so either your pre-amp is set to be quite light in lower mids, or you have a problem in the power stage.
I really wouldn't expect a forty odd watt jtm to have less air moving capabilities than a fifty watt JCM800, less gain, not less body.
I'd suspect it's the power stage, in which case you could plug all the pedals you wanted into the thing and it'd never sound any better, but an eq pedal is probaby cheaper than getting an amp tech to check the power stage.
 
Re: How do I Beef up my amp?

A JTM45 circuit (even with a SS rectifier and 34s) does not make 42 watts at clipping. Maybe distorted but not at clipping. With KT-66's a healthy original JTM45 puts out about 35 watts at clipping- max. Most put out around 30 watts at clipping. The off the shelf re-issues with 5881's put out about 27 watts at clipping.

A 50 watt JCM800 puts out about 55 watts at clipping with healthy tubes and caps and up to 90 watts fully distorted. Another, factor with the plexi and JCM800 amps is the filtering. They will be 50/50 or more throughout. High filtering usually results in more precieved OOMPH. But also as a trade off often a boomy bass response, that amps with lower filtering are trying to avoid. Plexi and other SS rectifier designed for Marshalls also have different transformers and chokes from 45's.

I think the best course of action is to trade in for an 800 (or a plexi) rather than trying to get the 45 to sound more like an 800. You might like better the extra tightness and oomph of a 100 watt Marshall circuit too. They are very loud but so are 50 watt 800's, really. If you get a 100 watt Marshall circuit get one with a master volume.
 
Re: How do I Beef up my amp?

Speaking of JTM45s with EL34's if you will excuse a slight diviation from topic. I had to resort to this last night. One of the 6L6s died and all I had on hand were a pair of old almost used up =C= EL34's. After biasing it was quite different from 6L6. (I also got zapped so be careful always..) Brite and Tite. But really solid and full with a smidge hotter bias. This particular pair of tubes have always been tight in any amp. It was also louder.
 
Re: How do I Beef up my amp?

rgreen11 said:
Hey guys I have a JTM 45 Clone, which sounds really good but I don't feel like I have any power behind me. I hope this makes sense. It gets very loud but it lacks that extra oomph. I have a JCM 800 that I'm comparing it to. When I play the 800 you can really feel it but when I play the 45 you can hear it without a problem but like I say it doesn't have that oomph. Anything I can do to give me that oomph?
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The JTM is a great amp but different from an 800. You might try to hit the front end with a boost and see if that gets you what you're looking for.
 
Re: How do I Beef up my amp?

who made this clone?

with a ss recto and everything biased right you should have a thumpy amp, it wont sound the same as the jcm 800 for sure but it should have plenty of oomph.
 
Re: How do I Beef up my amp?

Gr8Scott said:
Could be bad tubes or it could be a cheap output transformer. It could also be a poorly constructed circuit. My JTM-45 clone built by Scott_F will outshake a Peavey XXX at full bore through the same or different cabs. It has a metric ton of bass.
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+++ 1,000

But against my original Blues breaker - Edena is second and the JTM-45 RI a distant third.

All are still better than my "Non-working" Ceriatone JTM-45. (Last time, I buy second hand equipment)
 
Re: How do I Beef up my amp?

thats what i was getting at when i asked who made it.

i kinda think that maybe the old jtm 45's had a different (higher) primary impedance than more modern marshalls which would lead to a richer but less stout tone

also does your jcm 800 run 6550's or el34's?
 
Re: How do I Beef up my amp?

You could always get new transformers or a different choke. Mercury has a line of transformers that have more Iron in them which fattens up the bass response. I haven't used them and I know transformers don't make a day and night difference but it will help. I'm interested in getting them for my JVM but its pricey.

I'm also going to get a 10H choke to fatten up the bass response and tame the highs. Your Marshall should have a choke in there already since big resistors weren't around then to fill the role of the choke. I'd look into different types of transformers and chokes.

Thats the pricey stuff though. Look into other tubes as well. In that Marshall the power tubes will matter so look at some thicker chunkier power tubes. Preamp tubes are going to play a large role too. Any single channel amp makes tubes shine through way more than a channel switching amp. Most of my tone problems are solved with tubes and mine isn't a single channel amp so try that first.

Sorry if someone stated this already I didn't read past the 3rd response.
 
Re: How do I Beef up my amp?

The transformers are Hammonds, the output is modal 784-103 and the power is 1202 -55 it has a mercury magnetics choke JT45C-7H all the caps are sozo's. I'm from Ohio and a local guy built the amp. As far as my JCM 800 it uses 6550 power tubes. I've been fooling around with the EQ lately and I'm getting better results.
 
Re: How do I Beef up my amp?

6550's will certainly sound "bolder" with more "thump", especially in the 800 circuit.

I think you really should try KT-66 tubes in the 45. Regular 5881/6L6 types don't have the beef of a KT-66. And the EL34 is generally best suited for more of a smooth violinesque lead guitar tone. The KT-66 has more beef but it also will sing when pushed.
 
Re: How do I Beef up my amp?

Just take some nice raw roastbeef and stuff it in the back cavity in between the tubes, once it starts to smell like roasted meat it will be beefy and you might get something warm to east after some hours of playing
 
Re: How do I Beef up my amp?

Loserchief said:
Just take some nice raw roastbeef and stuff it in the back cavity in between the tubes, once it starts to smell like roasted meat it will be beefy and you might get something warm to east after some hours of playing
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dang man, ya beat me to it. i was gonna post somethin' along the same lines but couldn't think of how to word it:)
 
Re: How do I Beef up my amp?

If you haven't done this already, turn all of the tone knobs on the JTM all the way up and then start bringing up the volume.
 
Re: How do I Beef up my amp?

Rich_S said:
The JTM45 has a tube rectifier, no? It's simply a spongier-sounding amp.

Or, you could accept that the JTM45 has its own sound, and use it when that sound is what you're looking for. They are wonderful-sounding amps, but not all-purpose.
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That's around my thought.

A Twin is really good at being a Twin. If you want something like a Twin, get a Showman into a 2x12.

By the same rights, the JCM800 is not going to sound like a JTM style amp.
 
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