Using the FX loop as a master volume...

[dr_love6977]

I've heard about this a couple times in the past few days. How does this work?

[dr_love6977]

Ok, I tried it. I put a jumper in the loop, cranked the channel volume, then used the fx level as a master. I liked it. The amp thinks it's cranked, right? I know the Mesa tone is best cranked, but I live in an apartment, so I don't get to push it hard.

[Sixtonoize]

Nope. Attenuating the volume in the FX loop is the same as using your master volume.

What you're essentially doing is decreasing the amount of power that you send to the power tubes. To really get "cranked" tone, you've got to use something AFTER the power tubes i.e. an attenuator like a Hot Plate, Mass, or PowerBrake.

[dr_love6977]

Nope. Attenuating the volume in the FX loop is the same as using your master volume. What you're essentially doing is decreasing the amount of power that you send to the power tubes. To really get "cranked" tone, you've got to use something AFTER the power tubes i.e. an attenuator like a Hot Plate, Mass, or PowerBrake.

 

 

{censored}. It sounded different, and I got to back down on the gain a lot. I guess the difference in sound was just the loop's coloration, eh?

[Dann'sTheMan]

The short answer is: Trust your ears. If it sounds better, then go with it. How it works is not so important.

 

The long answer is: There are a number of reasons why it can work and it's nothing to do with increased Power Amp distortion (as many posters will doubtless mention). With Mesa designs, the channel volumes are typically placed before the FX loop. Turning up the channel volumes allows the pre-amp tubes to be driven harder - and with an amp that is primarily voiced around its pre-amp, like Mesas are, this is a good thing. Some amp designs vary the amount of negative feedback, so this may also explain why the amp can sound different depending on where the channel volumes are set. Finally, in amps with a tube driven loop, driving a hotter signal through the send side of the loop can saturate another pre-amp valve section and again change the tone (usually for the better). How much each one of these factors is contributing to your improved tone is not so important - basically trust your ears!

 

Big smiles,

 

Andy.

 

P.S. Using the FX loop to attenuate volume is one of the most popular mods discussed by F-series owners in the F-series Lounge (link in sig). It works briliantly for me, my F-50 and my G-Major.

[Herald of Light]

Depending on the design of the amp, as noted, there could be other things you're pushing that are past the master volume in the signal path, which would explain the difference in sound.

[dr_love6977]

Sweet, thanks a lot guys!

[DoubleBarrel]

This is where Mesa's fail as they have a parallel loop instead of a series like a Marshall.

You can have it modded to be series, but if you have a solo function, you'll lose it.

[dr_love6977]

This is where Mesa's fail as they have a parallel loop instead of a series like a Marshall. You can have it modded to be series, but if you have a solo function, you'll lose it.

 

 

What's the diff between a series loop, and a parallel?

 

I don't have a solo function, I have a 2 channel.

[DoubleBarrel]

What's the diff between a series loop, and a parallel? I don't have a solo function, I have a 2 channel.

 

 

Parallel = 50% or more is unnaffected by the loop, so you get 2 signal paths

 

path 1 = 50 or more of singal goes direct to power amp without going thru the loop

 

path 2 = 50% or less of singal goes thru loop then to power amp

 

 

there is also usually a buffer to prevent hugh volume differences. So and eq in the loop will not work as a lead boost.

 

 

 

 

Series = 100 % the signal goes thru the loop

[dr_love6977]

Parallel = 50% or more is unnaffected by the loop, so you get 2 signal paths path 1 = 50 or more of singal goes direct to power amp without going thru the loop path 2 = 50% or less of singal goes thru loop then to power amp there is also usually a buffer to prevent hugh volume differences. So and eq in the loop will not work as a lead boost. Series = 100 % the signal goes thru the loop

 

 

Ahhh... who does these mods? Cost?

[DoubleBarrel]

Ahhh... who does these mods? Cost?

 

 

 

I'd chekc with JerryP @ FJA http://www.fjamods.com/

 

or

 

Trace @ Voodoo. http://www.voodooamps.com/home/

 

You might just want them to add a footswitchable "solo volume" knob, and leave the path as it is.

[dr_love6977]

I'd chekc with JerryP @ FJA http://www.fjamods.com/ or Trace @ Voodoo. http://www.voodooamps.com/home/ You might just want them to add a footswitchable "solo volume" knob, and leave the path as it is.

 

 

Cool, thanks for the info man!

[DoubleBarrel]

Cool, thanks for the info man!

That's why we are here

[Dann'sTheMan]

Parallel = 50% or more is unnaffected by the loop, so you get 2 signal paths path 1 = 50 or more of singal goes direct to power amp without going thru the loop path 2 = 50% or less of singal goes thru loop then to power amp there is also usually a buffer to prevent hugh volume differences. So and eq in the loop will not work as a lead boost. Series = 100 % the signal goes thru the loop

 

I'm not sure where you get your information about parallel loops, but you may want to re-investigate. I've seen the very occasional manufacturer that uses the strange 50% fixed wet mix loop, however, Mesa isn't one of them, and like most manufacturers that offer a parallel loop, a variable mix level control is provided so that you're not fixed at 50% wet mix.

 

All of the Mesas that I have seen with parallel loops can allow at least a 90% mix to be set, some can go to 100% - which is effectively serial (pun intended), and some of the high end models have both serial and parallel loops.

 

My F-50's parallel loop goes from 10% to 90%. At the 90% setting, I find, as do many F-series owners, everything works brilliantly. I use my parallel loop for solo boosts without a problem. The mod to serial involves a simple soldering of two wires and as an EE, if my parallel loop were a problem, I would have made this easy change long ago.

 

For those that do have problems with a parallel loop, the mod to serial seems to resolve most issues. I can't comment about losing the newer Recto's solo boost feature because my F-50 doesn't have this, and getting my solo boost from my G-Major works excellently. However, this part of Mesa's amp designs is usually pretty straight forward, and I suspect armed with the circuit diagram, a slightly more involved mod could keep the solo boost feature active,

 

Big smiles,

 

Andy.

 

Big smiles,

 

Andy.

 

P.S. The Express series has succeeded Mesa's F-series and this range happens to use a serial loop.