Mark V 90w signal too hot? Fx Loop issues?

[OlBoyMikeRyan]

Hey guys,

I've got a Mark V 90w combo that I use predominantly on channel 1, switching between 'fat" and "tweed" setting. I've lately noticed an issue with a few of my pedals, namely the 29 Pedals Euna and the GFI Synesthesia. It seems that the signal from the Mark V is too hot somehow and is causing clipping. The Synesthesia clips when any overdrive is introduced. The Euna acts as an overdrive even though it's not supposed to. I spoke to Jesse of 29 pedals and he assured me there should be no added overdrive when Euna is engaged.

I've noticed in the past that there have been issues with using my Mark V effects loop. It tends to stop working completely whenever I reconfigure the pedals in the loop. It seems pretty random and the situation resolves itself some time later.

Any thoughts? I'm at a loss at how to fix this. I like both of these pedals and would like to keep them. No idea why they're behaving the way they are. I've done a lot of troubleshooting. It's not the cables, power cables, power supply, other pedals or guitar.

 

[mace]

I think this is a known characteristic of the Mark V. The signal going to the FX loop can be too strong for some pedals.

You can turn the channel masters down to reduce the FX send signal. The channel master level affects the signal strength to the FC loop. Also, you can adjust the dial on the back of the amp for FX send level.

Hopefully you can dial down the send level to a compatible level for your pedals.

 

[rarebitusa]

The signal output is indeed hotter on the Tweed voicing vs Fat. As Mace said the chan master plays into it. FWIW the manual has this way of testing if the levels across the loop chain is correct

"Adjust the SEND LEVEL control on the Rear Panel of the MARK V to achieve an adequate match on the INPUT level indicator
of your processor. Adjust the processor Output level stage (hopefully your processor has an OUTPUT LEVEL control) to match
the volume present before connecting the device(s) to the MARK V. You can check this by simply removing both the cables from
the SEND and RETURN simultaneously."

 

[OlBoyMikeRyan]

thanks guys! I actually tried dialing down the send level on the back of the amp. It seemed to help A LITTLE but not enough.

@rarebitusa that's a little confusing. What is the processor? Just the system the mark V uses? I'm a bit confused. Remove both cables simultaneously and look for what, exactly?

You know...I oft think it was ambitious for me to get such a difficult amp, but I wanted it all!

Thanks for the help guys.

 

[Eevil]

Some pedals just won’t work in the line level loop pedals are usually designed to work in guitar signal levels only.

Just like plumbing pipes and fresh water pipes - one should not mix those in the same pipeline

 

[rarebitusa]

thanks guys! I actually tried dialing down the send level on the back of the amp. It seemed to help A LITTLE but not enough.

@rarebitusa that's a little confusing. What is the processor? Just the system the mark V uses? I'm a bit confused. Remove both cables simultaneously and look for what, exactly?

You know...I oft think it was ambitious for me to get such a difficult amp, but I wanted it all!

Thanks for the help guys.

Yea it is a bit confusing I do admit. So what they are trying to outline is that the same output level is seen with the loop pedals in vs with them pulled out.

Anyway, did the pedals in the ever sound ok? You mentioned that " It tends to stop working completely whenever I reconfigure the pedals in the loop. It seems pretty random and the situation resolves itself some time later." That shouldn't happen just wondering if something else is going on. The only tube in the FX loop is the V6B. You could try swapping tubes around.

With it acting up... if you bypass the loop (footswitch or rear panel HARD BYPASS/LOOP ACTIVE mini toggle) how does the overall volume react? Do you notice a difference in the problem between FAT vs Tweed?

 

[domct203]

You could try using a signal level switcher to reduce the level before the pedals then bump it back up on the return. I’ve done this with the Ebtech Line Level Shifter, which looks to now be made by Morley. Not sure if it’s the exact same unit.

Dom

 

[OlBoyMikeRyan]

Some pedals just won’t work in the line level loop pedals are usually designed to work in guitar signal levels only.

Just like plumbing pipes and fresh water pipes - one should not mix those in the same pipeline

Wait, but isn't the FX loop made for those types of pedals? For reference, the EUNA is in front of the amp and the GFI synesthesia is in the loop. Those are the only two who are "clipping" because of the hot signal. Everything else sounds fine.

 

[OlBoyMikeRyan]

Yea it is a bit confusing I do admit. So what they are trying to outline is that the same output level is seen with the loop pedals in vs with them pulled out.

Anyway, did the pedals in the ever sound ok? You mentioned that " It tends to stop working completely whenever I reconfigure the pedals in the loop. It seems pretty random and the situation resolves itself some time later." That shouldn't happen just wondering if something else is going on. The only tube in the FX loop is the V6B. You could try swapping tubes around.

With it acting up... if you bypass the loop (footswitch or rear panel HARD BYPASS/LOOP ACTIVE mini toggle) how does the overall volume react? Do you notice a difference in the problem between FAT vs Tweed?

Oh this part is interesting. When I bypass the loop (via back toggle switch) there is a MASSIVE volume increase. To the point where it's painful to the ear. This is interesting and strange to me because I always have the amp's overall output set incredibly low.

 

[domct203]

Oh this part is interesting. When I bypass the loop (via back toggle switch) there is a MASSIVE volume increase. To the point where it's painful to the ear. This is interesting and strange to me because I always have the amp's overall output set incredibly low.

If the Euna is in front of the amp and clipping your guitar is too hot for the pedal. What pickups do you have? Are they active? Any pedals before the Euna?

If the volume level changes when you switch the FX Loop in/out your not at unity gain somewhere in your FX Loop signal chain. Not all stomp boxes are made for a line level signal or the impedance of a line level signal. You’ll find yourself reducing the signal into your effects to avoid clipping, without make-up gain somewhere post effects your overall signal is going to be lower. An impedance mismatch can also cause signal issues. When you bypass the loop you are removing those restrictions and getting full signal to the power amp, that tells me your return signal from the FX Loop chain to the amp is weak.

This is why I went to a G-Major years ago. It is made for line level signal, with input and output level control and an input signal level meter. When I setup my FX Loop I turn down the output control of the G-Major to zero and adjust the input signal to about -3 or -4dB peak on the VU meter of the G-Major, then bring up the output control until I have the same volume with the FX Loop switched in and out. That is unity gain.

You can do the same with pedals but it has to be done by ear. If there’s a pedal in the FX Loop chain that is not made to handle a line level signal you’re always going to have to compromise somewhere.

BTW I found the MKV90 to have the hottest FX Loop signal of any amp I’ve owned, including all my Mesas.

Dom

 

[rarebitusa]

Wait, but isn't the FX loop made for those types of pedals? For reference, the EUNA is in front of the amp and the GFI synesthesia is in the loop. Those are the only two who are "clipping" because of the hot signal. Everything else sounds fine.

Oh this part is interesting. When I bypass the loop (via back toggle switch) there is a MASSIVE volume increase. To the point where it's painful to the ear. This is interesting and strange to me because I always have the amp's overall output set incredibly low.

Sounds like the channel masters are pretty hi, You could try bringing them down and see if that helps.

 

[mace]

Yes, this will help. To bring the channel masters down to around 9 to 11 o'clock will help. The channel master level is related to what level is sent to the loop. So, if those are up above 12 o'clock, the level being sent to the loop will be pretty high.

Of course, if the loop is off and then the channel masters are the final volume you hear on the amp, it doesn't take much to get the ears to bleed. Around 9 or 10 o'clock on the channel masters will do it in 90W mode!

 

[OlBoyMikeRyan]

Yes, this will help. To bring the channel masters down to around 9 to 11 o'clock will help. The channel master level is related to what level is sent to the loop. So, if those are up above 12 o'clock, the level being sent to the loop will be pretty high.

Of course, if the loop is off and then the channel masters are the final volume you hear on the amp, it doesn't take much to get the ears to bleed. Around 9 or 10 o'clock on the channel masters will do it in 90W mode!

Ah, that did it! It was the individual channel master being too loud! You guys are the best. I turned the channel 1 master down to about 9 o'clock and compensated for the loss of volume by turning up the general output knob and we're all clear. The Euna, for those who may have been curious, really does sound absolutely wonderful now.

 

[OlBoyMikeRyan]

If the Euna is in front of the amp and clipping your guitar is too hot for the pedal. What pickups do you have? Are they active? Any pedals before the Euna?

If the volume level changes when you switch the FX Loop in/out your not at unity gain somewhere in your FX Loop signal chain. Not all stomp boxes are made for a line level signal or the impedance of a line level signal. You’ll find yourself reducing the signal into your effects to avoid clipping, without make-up gain somewhere post effects your overall signal is going to be lower. An impedance mismatch can also cause signal issues. When you bypass the loop you are removing those restrictions and getting full signal to the power amp, that tells me your return signal from the FX Loop chain to the amp is weak.

This is why I went to a G-Major years ago. It is made for line level signal, with input and output level control and an input signal level meter. When I setup my FX Loop I turn down the output control of the G-Major to zero and adjust the input signal to about -3 or -4dB peak on the VU meter of the G-Major, then bring up the output control until I have the same volume with the FX Loop switched in and out. That is unity gain.

You can do the same with pedals but it has to be done by ear. If there’s a pedal in the FX Loop chain that is not made to handle a line level signal you’re always going to have to compromise somewhere.

BTW I found the MKV90 to have the hottest FX Loop signal of any amp I’ve owned, including all my Mesas.

Dom

Hey Dom,

I'm trying to understand this all. So the fx loop is a line signal and not a guitar/instrument signal? Aren't most modulation and time based effects made to be placed in the loop? How can I ensure there isn't an impedance mismatch?

 

[rarebitusa]

FWIW there are also passive line level shifter boxes that covert between instrument and line levels. But it seems you have found a solution... time to rock on

 

[domct203]

Hey Dom,

I'm trying to understand this all. So the fx loop is a line signal and not a guitar/instrument signal? Aren't most modulation and time based effects made to be placed in the loop? How can I ensure there isn't an impedance mismatch?

Not all stomp boxes are made to be used with line level signals, and not all FX Loops are at line level. If you are happy with your sound and you are at unity gain don’t get hung up on impedance. Just rock on and enjoy!

Dom

 

[OlBoyMikeRyan]

Thanks guys, I appreciate it. Using this amp is always a learning experience.

 

[KRichter]

Line level thru the loop. Designed that way. Otherwise you'll get mixed results.