Confused about the FX Loop on the MKV...

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Mark II
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Confused about the FX Loop on the MKV...

Post by jaslan » Sun Apr 29, 2018 5:15 pm

The manual says the FX loop is in series but it is behaving like it is in parallel. I have an H9 in my effects loop which has an output level adjustment.
If I reduce the output level of the H9 all the way down, I can hear the dry signal (as it is before going to the FX loop). It is really strange.
I have a stereo setup with another amp with an effects loop which is also going to the H9. When I turn the output of the H9 down, that amp passes no signal to the speaker.
What am I missing?

OK. I found this thread...
Which discusses the bleed from the send to the return. But I am not sure that is what is happening here. If I turn down the output of the H9 in the effects loop, I still hear the dry signal at basically the same volume as if the FX loop was not even turned on. I will need to experiment some more... I play at very low volumes in the spare bedroom...

Did some more experimenting. In the other thread it talked about the bleed being a percentage of the loop signal. I am getting a fixed level of bleed and the only thing that seems to change it is the gain of each channel. It is the worst in channel two for me. Even though I have the gain fairly high on channel three, the bleed is not as bad as channel two with the gain at about the same level. It is also true that as I raise the "Output" level (the master volume with the FX loop enabled), the bleed through stays the same so, playing at a louder volume does start to drown out the bleed through signal.

I will say that after having my Mark V for about three years now, I have found the first significant thing I dislike about it. This is a significant design flaw. Seriously, at really low levels, the dry bleed through signal actually drowns out the wet signal from the return. I use 45W mode in all channels. I don't like using 10W mode because I get some fairly disconcerting pops when switching channels.

Does anyone know if there is a fix or mod for this? Or maybe it is not supposed to be that way and I can send it in and get it fixed. I am guessing not because it looks like others report the same thing and it is just inherent in the design of the amp...

Anyway, I am a little bummed about it right now but I am sure I will get over it.

Mark I
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Re: Confused about the FX Loop on the MKV...

Post by Rider1260 » Sun Apr 29, 2018 9:51 pm

My MKII if you muted the signal going thru the loop there was NO sound like you were saying on my newer amps ( MKV and a PRS H ) there is always some sound ( Bleed if you like ) even when the device in the loop is muted.
This seems to be normal just means I cant do 100% silent tuning when using my TC Electronics Nova in the loop with my setup.
If you want to disable the loop I just use the footswitch
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Mark II
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Re: Confused about the FX Loop on the MKV...

Post by jaslan » Tue May 01, 2018 5:56 pm

For me it’s not about silent tuning or silencing the loop. It is about getting a 100% wet reverb or delay sound. Impossible at bedroom levels with the effect in the loop.

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Re: Confused about the FX Loop on the MKV...

Post by LesPaul70 » Fri May 04, 2018 12:34 am

jaslan wrote:I play at very low volumes in the spare bedroom...
jaslan wrote:Impossible at bedroom levels with the effect in the loop.
There's your problem. This was already said in the thread you linked.

Your Mark V was not designed to be a bedroom amp. Even a 10W tube amp can be loud. Skimp on the volume, and you're bound to get suboptimal performance in more ways than one.
jaslan wrote:Does anyone know if there is a fix or mod for this?
Yes, there is, it's your master volume knob. Just turn it up a notch.

You don't need earsplitting volumes (this is not a vintage Fender we're talking about here! :lol: ), just a little bit louder than your speaking volume.

If that cannot be done...I dunno. An attenuator might help.
(Also, some people like to suggest that digital devices like Axe-FX are better suited to bedroom volumes than high-power tube amps.)

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Re: Confused about the FX Loop on the MKV...

Post by jaslan » Fri May 04, 2018 8:57 am

I agree that a 90 W amp was not designed for optimal performance at bedroom levels. I have considered an attenuator before for the purpose of recording primarily but now I think I will look into that again. I bought the 90 W version for the features it has which aren't available on smaller models. I also own a JVM410 which I bought because the 50W versions don't have all the features. I get it that the manufacturer has to develop a line of products that will sell well and there probably isn't a high demand for a 50W or 25W version of an amp with all the bells and whistles. FWIW, the JVM has no bleed of the dry signal in the loop, which is ironic because it has a wet/dry mix knob for the effects loop and is technically a parallel loop. I also accept that there may have been something in the way that Mesa designed the loop which provides a benefit that I don't understand and they chose to do it that way in spite of the dry signal bleed through.

Bottom line is that I do still turn the amp up when I need to, I just can't always do that which puts some limitation on my use of the amp. There will ALWAYS be some limitations, of course, and I accept that. I still am absolutely happy with my MKV because ultimately it is about the sound, which just can't be beat. I haven't owned and played tons of amps but I have owned and played quite a few and the MK V is my favorite.

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Re: Confused about the FX Loop on the MKV...

Post by bandit2013 » Mon May 07, 2018 6:21 am

Try plugging in a dummy cable into the return jack. This is supposed to break the signal path in the FX loop when the FX is set to active mode and the loop turned on. You should not hear anything at the speaker. If you do, the switch on the Return jack is not working properly. The send jack does not have a switch and you can almost use that as a signal send to another amp and still get the signal though the amp to the speaker. I would suspect the plug you are using or the jack may be to blame for the dry signal being as loud as the non-FX loop signal.

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Re: Confused about the FX Loop on the MKV...

Post by emurphy94108 » Wed Aug 08, 2018 11:22 am

I noticed one odd thing about the FX loop and the way it interacts with the "Output" control.

I was trying to balance the overall amplifier volume between having the FX loop engaged and when it's out of the signal path (I'm actually using my DAW's digital stomp-boxes in the effects loop, but that's an irrelevant detail). The difference was minor, maybe -1 or -2 dB with the loop engaged, but enough that I noticed it. I assumed that setting the send level on the back of the amp would be the way to do this, but that doesn't actually work: as you turn up the send level, the overall volume of the amp goes up as well, even with the FX loop out, so you end up chasing your tail.

It seems the way to do it, then, is to increase the output volume settings on whatever effects you have in the FX loop. As it happens, at least with Logic Pro running the FX loop, the throughput gain is 0 dB, i.e., whatever the input gain from the FX send is matches the output level exactly. So I think if I wanted to match the volume exactly with the FX loop in or out, I'd just increase the output level being sent back to the amp.

This does, however, provide a handy output volume control for the amp if, say, you're playing your guitar in the control room but the amp is out on the other side of the glass. Just turn down the level on the DAW output that's sending the processed signal back to the Mk V's FX return.
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