Dull sounding Marshall amp.

[stgaudio]

did he re-tube?

[frosty555]

He did a full service. Cleaned all the pots, fitted new power and preamp tubes (matched quad), replaced the electrolytic caps, adjusted the bias and fitted a send/return to the back.
The actual 2x12 I play it through is ok with another valve amp I have. Its the Marshall thats the issue somehow.

[frosty555]

On some advice earlier, I put a patch lead over the send/return and the clarity is all there !!
Whats the deal here then?

[chaosgow]

I had the same thing with a TSL combo. I never did find out why, it was an awesome amp with that cable in place

[frosty555]

It still doesnt cure the problem. I need a send/return for effects etc...

[nedorama]

Have you talked with your tech about this problem? It would be my first call.

Unfortunately, I'd guess for your tech adding this send/receive mod was above his capabilities. A correct mod shouldn't change the amp, but then again, many mods on older amps don't always make them better and may introduce other problems.

I never understood the benefit of the effects send in an amp (vs. a mixing board) but would suggest the tech reverse/remove the send/receive until you can find someone who can do it properly.

[crosscutred]

Originally Posted by frosty555

It still doesnt cure the problem. I need a send/return for effects etc...

If your amp sounds right with a lead across the new mod, it will sound right with the effects inserted. Your problem is with the internal bypass.

That is assuming the mod is in the correct part of the amp's signal flow..... if not then you could have problems.

Sent from my HTC Desire using Tapatalk

[Silent Sound]

This is the reason why I don't own any amps with effects loops anymore. Effects loops always seem to suck tone. Maybe not on all amps, but on all the ones I've tried, there's just a loss of clarity. So now I just put my effects out in front and use a booster/buffer pedal. The only effect pedal that I "needed" to have in an effects loop was an EQ pedal to help sculpt the amp's distortion to a more usable sound. But even that was a bad fix to a big problem. I was much happier when I just sold that amp all together and got something better. Maybe you could try inserting a booster/buffer pedal in the effects loop and see if that helps restore some of that clarity.

[frosty555]

A "booster/buffer pedal"..?

[nedorama]

Again, go back and talk to the tech. It's possible he didn't mean for this to sound like this. Or you'll find out this guy doesn't know amps and shouldn't have touched your JMP in the first place. Report back what he says.

[frosty555]

The pedals that I have actually going into the effects loop are...MXR 10 Band graphic, Behringer TU300 Tuner, Behringer DR400 Delay, Boss BF-2 Flanger.

[Arichlsss]

Try the pedals one at a time to figure out if it is just one of the pedals or all of them together.

[frosty555]

Mmmmm. Hadnt thought of that one. Will give it a go.

[nedorama]

In general, effects loops are for modulation effects, like delay, chorus, flange. You shouldn't be running your tuner or graphic EQ in the loop - they should be going through the input jack up front.

Amp should sound the same with nothing in the effects loop, a patch cable connecting the send/return, and any effects inserted. If not, either the amp mod or a pedal/cable are defective.

[chaosgow]

Originally Posted by nedorama

In general, effects loops are for modulation effects, like delay, chorus, flange. You shouldn't be running your tuner or graphic EQ in the loop - they should be going through the input jack up front.

I agree with not running a tuner in there, but what's so bad about putting an EQ in the loop?

I've done it in the past and liked it.

[nedorama]

It's why I said "in general". If you like the sound great. Bigger issue is an unknown insert mod that may or may not have been done correctly. It's why I avoid those kind of mods.

[crosscutred]

It seems like you're not sure if the problem is the mod or the pedals that you are trying to insert.

That needs establishing. Try the amp without anything plugged into the effects loop. Does it sound fine?
We know its fine with the patch lead across it.
Is it the introduction of pedals that causes problems?
Is it all the pedals or just one?
Is the pedal at fault or is it the impedance mismatch that is causing the problem?

When you have answers to all those questions you should know what to do.

[frosty555]

Originally Posted by chaosgow

I agree with not running a tuner in there, but what's so bad about putting an EQ in the loop?

I've done it in the past and liked it.

The reason I have the MXR Graphic in the loop is the only way I can get a volume boost for playing solos. Its a single channel amp. I got the Delay in the loop also, as I read lots of Delay pedals sapping the tone big style if you go straight into the front end. Apparently it makes your guitar sound like you have a 100ft. long cable, its saps the signal so much.

[chaosgow]

Originally Posted by frosty555

The reason I have the MXR Graphic in the loop is the only way I can get a volume boost for playing solos. Its a single channel amp. I got the Delay in the loop also, as I read lots of Delay pedals sapping the tone big style if you go straight into the front end. Apparently it makes your guitar sound like you have a 100ft. long cable, its saps the signal so much.

A good delay pedal shouldn't suck your tone in front of the amp. You have a really nice amp that I'm personally fond of, and I've used it with delays in front of it with no issue.

Take your amp back to your tech. Get him to hear what you hear and fix it. He shouldn't charge you twice for fixing the first job but he might.

Once you get it back, you really should experiment with pedal positioning yourself and try not to go on what you've heard! Try as many pedals as you can get your hands on in as many positions as you can.

[nedorama]

Originally Posted by frosty555

The reason I have the MXR Graphic in the loop is the only way I can get a volume boost for playing solos. Its a single channel amp. I got the Delay in the loop also, as I read lots of Delay pedals sapping the tone big style if you go straight into the front end. Apparently it makes your guitar sound like you have a 100ft. long cable, its saps the signal so much.

Sorry, but whoever told you this doesn't know what they're talking about - they're an idiot. Thousands of guitar players run delays straight into the front end of their amps without this "sapping" you heard about.

You can also boost at the input as well, not just the effects loop.

Just so you don't think I'm spouting theory, I run an analog delay and a digital delay as well as a boost pedal IN FRONT of the amp. No effects loop, and my tone sounds the same as if I'm plugged straight in, no pedals.

I don't know where you're reading this stuff (probably here), but I'd ignore those people and try it for yourself. Does your delay sound different through the front end of your amp? Can you boost your amp with your EQ plugged in straight away? Only you can decide for yourself if you like the sound. Hoping you didn't get convinced to do this mod because of this "sapping" concern.

[drbob1]

Back to the effects loop question.

If it sounds dull with nothing in the loop, then you've got a problem with HOW it was implemented. Perhaps as simple as the shorting jacks are loading a susceptible part of the circuit causing high end loss. If true, he needs to fix it or remove it so someone competent can install it.

If it's only dull when pedals are installed then you've got an impedance matching problem. That can be fixed by adding another tube (to buffer the input and the output of the loop) or a solid state device, like a dual op amp to do the same. Or you could get a "loopulator", an external buffer that matches your pedal impedance to the amps impedance. Vox made one for a while, and many of the Dumble style amp companies build them, but they're not cheap. If that's not on the cards, then your best bet would be to place an always on/buffer pedal first in line and another one last in line inside the loop.

And yes, putting a delay, or any modulation before distortion in your signal chain can mean that the effect of the pedal is reduced but it's not going to hurt the basic sound.

[frosty555]

I have just finished trying to go from the guitar into the MXR Gaphic into the front end of the amp. No good. It wont boost the volume at all. It does when its in the effects loop though.

[drbob1]

Originally Posted by frosty555

I have just finished trying to go from the guitar into the MXR Gaphic into the front end of the amp. No good. It wont boost the volume at all. It does when its in the effects loop though.

If you're using primarily preamp distortion this is absolutely true: the preamp is already saturated and compressed so there's no more volume available there. If you've got a master volume, and the effects loop is essentially between the preamp and the power amp, then dropping the MXR in there will add volume, just like turning up the master would. If you don't have a master volume and your amp is giving you more volume with the MXR in the effects loop than you can get with it before the preamp, then something is broken in the effects loop implementation.