FX loop overloading MXR Black Label Chorus?

[eguess74]

Hi guys!

I just recently joined the club I'm in love with the amp, but have a question about FX loop:

I have connected the MXR Black Label Chorius in effect loop and on the clean channel I noticed that if I'm attacking the string agressively it produces some weird kind of clipping sound. I'm not positive if this happens only when the pedal is on, or when it is also in bypass mode - gotta double check that.

This problem is definitely gone when i put the chorus before the loop, but I'm not sure this is optimal position. I read some people recommend to keep the FX loop level in about 12:00 position. But i have a feeling it reduces the volume on the channel and i didn't figure out yet how to make FX loop output level the same as FX loop bypassed (I have only chorus and delay in the FX loop). Can it be that the signal on attack is to hot for this pedal?

Any ideas?
Thanks!

 

[Catthan]

Hi,

best keep the loop level at 12:00 max.
In order not to overload the input of the fx in the loop I keep the channel masters under 12:00 too.
That's what worked best with my LSS so I didn't bother testing further with the MkV.
Do you find that with the loop at noon and the channel master at noon the particular channel lack volume?
Is it imbalanced volume-wise compared to other channels?

I noticed the other day that if I turn the loop level to around 1 - 2:00, ch. 3 starts squealing when its master is higher than 9:00 with gain at noon..
It's a very fine balance between the loop level and the individual masters. Fortunately the MkV is loud enough to set the loop and the individual masters at noon max (to avoid noise and clipping the fx in the loop) and crank the master output.

 

[eguess74]

I have a feeling that if the FX loop level knob is at 12:00, then when I'm switching the fx loop on using the footswitch the volume drops comparing to the same channel with the FX loop off.
But if I add more to the FX loop level, then only on the clean channel i see this artifact appearing.
I will try to check once again today to describe precisely in which modes i get this problem.

I have a tendency of making all channels even in the perceptible volume and I'm also trying to make the FX loop not to stick out or drop below the main common level, so i don't have to touch the master volume at all when switching between channels. I don't know how common this practice is though, but I'd thing this is quite normal approach.

Again, i shoud probably be more specific and i will try again and report back my findings

thanks, Catthan!

 

[eguess74]

Intersting - this problem seems to be only visible when i'm using the single coil pup on my guitar, or a combination of half of a humbucker and the middle single. There is no such issue on the humbuckers... weird.

 

[eguess74]

Bummer!!

While i was playing today with the FX loop i noticed that the EQ bypass doesn't work!
I mean in any mode! I tried all combinations and it seems to be always in the signal chain no matter what.

Seems like it is completely disregarding both the EQ off and EQ FS settings on all channels. And it disregards the FS as well. Always on!

Not like it is killing me, but knowing that something wrong with such an expensive piece of equipment doesn't feel good...
I hope I'm not missing anything...

 

[LesPaul70]

I had a similar problem with my trusty EHX Small Clone chorus. No matter how low I set my send level, it would always clip for cleans, producing a very ugly distortion that pretty much ruined the clean sound. I tried moving the chorus pedal in front of the amp (it's a slightly different sounding effect there) but even that didn't solve the issue completely. What the pedal would have needed was input level control.

I'm not surprised if your problem is more perceptible with single coils. They tend to compress less and have a bigger dynamic range than humbuckers, so if you dig deep, you can overdrive and clip your chorus pedal input more easily.

My solution? You probably don't want to hear it but...
I removed the problematic chorus pedal :| and replaced it with a TC Electronics Nova Modulator. I might like the chorus sound of the EHX slightly better but the TC unit has input level control. (And of course it also has a lot of other effects.)

 

[eguess74]

Aha! Thank you for the explanation - I didn't think about the compression effect of singles vs humbuckers!
Well i guess i have to check the TC electronics then

 

[Ytsejammer777]

eguess74,
I had the exact same issue with mine. It was a resistor i believe that had gone out. A JFET something or other. Should be fixed free under warranty (or really cheap if not under warranty).

 

[eguess74]

eguess74,
I had the exact same issue with mine.

Are you talking about the EQ bypass? I will have to call mesa to find out the procedure, but mine is under warranty, luckily.

 

[Ytsejammer777]

Yes, sorry, the EQ would not turn off on any channel.

 

[eguess74]

So...
After some more testing I realized the following:
1. The problem with the pedal overloading is supposed to be solved by simple regulation of the FX loop send level.
2. Mesa engineers are smart

As obvious as it might sound now for whatever reason i didn't think about it from the beginning, but the FX loop level is the right way to go because of the way how it seems to be placed in the signal chain. Here is what i think is happening:

After the preamp section the signal goes to the switch that selects if the FX loop is active or not (back panel). If the switch is off, then right from there the signal goes to the amp. If it is on then the signal goes through the FX loop level regulator and only then it goes to the FX bypass switch that is controlled from the FS. In bypass mode the signal goes from FX loop level regulator to the amp, if the fx loop is on then it is a full path.
Therefore there is actually no volume jumps between FX bypassed or FX loop switched on (unless of course some effect in the loop amplifies the signal)

Makes sense?

As for the EQ bypass problem i have - seems like i gotta send it to Mesa for repair.

 

[eguess74]

eguess74,
I had the exact same issue with mine. It was a resistor i believe that had gone out. A JFET something or other. Should be fixed free under warranty (or really cheap if not under warranty).

So yes, you were right - bad transistor caused the problem with the EQ bypass switching. Mesa fixed it under warranty. Waiting for it to come back home now