Mini-Recto FX Loop hissing?!

[MrSmitty]

Love my new Mini-Rec! But having a small issue with the FX loop hissing. I'm wondering if anyone else has this issue?

The problem occurs when effects are plugged in the back of the amp and loop engaged. When effects are NOT plugged in, but loop still engaged...the hissing does not occur. It doesn't matter if I run the TC Electronics G-Major or individual effects pedals. However the hiss is the worst when the G-major being used, even with the noise gate on. I use that same G-major with my Mark V and it's quiet as a mouse, so I know it's not the effects unit.

I decided to try replacing the FX preamp tube, but problem still occurs. SO, I called MESA and expalained situation to them. The person I spoke to said he had not heard of any other issues with the Mini-Recs like this before. He said that perhaps because the Mini-Rec does not have a "FX send level and Output control" (like the Mk V) that would create less control over the effects signal, causing a noisy signal?

Has anyone else experienced this?

 

[Addictedtokaos]

The mini works the same way as the single rectifiers. Your channel's master control is also the FX send level.

If you turn down the volume is the issue still there? If it does go away, its because the volume you want to run the mini at causes the signal to be to hot for your fx in the loop.

 

[MrSmitty]

The hissing is there regardless of volume level, even if the volume is on "0". The hissing is least noticeable on the Clean channel and MOST noticeable on Modern mode, presumably due to the jump in gain.

 

[waygorked]

I'm getting the same issue with my Mini. With the loop switched off, dead quiet. With an extremely high quality cable plugged directly from send to return, also dead quiet, with a barely perceptible hum if I drape the cable over the output transformer. The same result with an identical cable. I can repeat those results with cables of varying lengths, with the cables placed anywhere in the room, and get no noise whatsoever.

But as soon as I plug 2 cables together into anything whatsoever (various hard bypass pedals, TC G system), I get about 30db of hiss. Not hum - this is most definitely not a grounding issue. No level changes, just stupid levels of hiss.

I love the sound of my Mini, just like I loved the sound of my TA30. I got rid of the latter due to endless loop problems. Mesa denied any knowledge of the TA30 problems despite several posts on this board with the same issues. I suspect that I'll get the same response if I call them about this issue.

I'm ready to punt on the whole Mesa project, no matter how good they sound.

 

[Si.]

I've not had this problem with mine, loop is quiet with my pedal board.

 

[MrSmitty]

I've not had this problem with mine, loop is quiet with my pedal board.

What kind of pedal board set up are you using?

 

[waygorked]

I tried putting a noise gate in the loop, and it didn't seem to make much of a difference. It cleaned up the input signal a bit, but the elevated noise floor persisted.

I called Mesa yesterday, and they had no good ideas for me. One of their techs thought that it couldn't be an amp problem if plugging a cable directly through the loop wouldn't recreate the issue. I told him that the noise is present completely independent of anything to do with either the gain or master levels, and is present with both set to zero as soon as the loop cables are plugged into any piece of equipment. At which point he seemed lost, couldn't see how it made sense, and told me he'd get back to me.

Any other ideas?

 

[markblasco]

Here is my guess as to what is happening: Since the mini recto doesn't have a master volume, anything you plug into the FX return will come out of the amp at full volume. This means if your FX makes any noise at all (and all of them do to one degree or another), that noise will come out of the amp at the same volume as if you had it plugged into the front end of the amp with the volume controls turned all of the way up.

I had the same issue when I purchased an m13 FX unit. I wired it up both before the amp and in the FX loop (which it is designed to do), and the first time I went through the presets, I nearly went deaf when I started to get crazy volume from my amp, even though the amp was turned down. One of the FX in the loop was producing sound, and that sound was coming out at a crazy volume. I also noticed that on the patches with FX in the loop that didn't make sound on their own (like delays), there would be a ton of hiss.

My solution was to make a master volume in a box. I just created a volume control by putting a 250k pot from a guitar in a small enclosure, and wired it up to an input and output jack. The output of my FX unit in the loop goes to the volume control, and from the control it goes to the FX return input on the amp. I then turned the individual volumes of the channel masters most of the way up (to about 2:00).

Since the signal coming into the FX unit is now at full volume, I can turn the volume way down in the loop to bring down the volume of everything, and this makes the noise barely louder than if there was nothing there in the first place.

So, in summary, I think what you are describing is an issue for all amps that don't have a master volume control after the loop, and is something that would be less noticeable when you are playing at higher volumes.

If you have a volume pedal, try putting it in the loop after all of your FX, turn up your channel master volumes, and turn down the volume pedal. I'm guessing this will solve everything.

 

[markblasco]

After reading this thread again, I am almost certain that the lack of a master volume is the issue, and the reason that some people don't notice it is because if you have your amp up at gigging level, the noise is down at the level of the noise floor of the amp. My guess is that the people who are noticing this issue are people who play the amp at lower volumes in quieter spaces.

If you have the chance, try turning your amp up to a gigging level, loud enough to compete with a drummer. My guess is at that point the noise level of the loop will seem pretty low.

Trust me, once you put a master volume in your FX loop, you'll never go back, it is wonderful! If I could add one to the amp itself I'd do it in a heartbeat, but with so little space in that amp, I don't want to risk messing something up.

 

[Addictedtokaos]

The FX loop is does not send at "full volume". It sends at whatever volume you have your channel master volume set to.

And to clarify, The mini has 2 master volume controls, one for each channel. What the mini is missing vs a Dual/Triple is the Master "output" control and "Send Level" control.

Also, if you read the replies, even with the master for that channel set to 0 they are still getting the issue, so adding a second pot in the fx loop will work if you want to achieve preamp tube breakup and bring the level down before your first fx pedal, but I dont think it would solve the issue they are experiencing.

 

[markblasco]

The FX loop is does not send at "full volume". It sends at whatever volume you have your channel master volume set to.

And to clarify, The mini has 2 master volume controls, one for each channel. What the mini is missing vs a Dual/Triple is the Master "output" control and "Send Level" control.

Also, if you read the replies, even with the master for that channel set to 0 they are still getting the issue, so adding a second pot in the fx loop will work if you want to achieve preamp tube breakup and bring the level down before your first fx pedal, but I dont think it would solve the issue they are experiencing.

I understand that the FX send level is controlled by the masters for each channel. What I am saying is that the FX return goes straight to the poweramp at full volume, there is no level control at that point. So, even if you have your master volumes turned all the way down for your individual channels, if you have signal coming into your FX return, it will still come out of the amp.

You can test this easily yourself by plugging your guitar directly into the FX return. When you do this, the volume controls of each channel have no effect on the volume of the guitar, because they happen at the preamp output.

So, you can imagine it as if you had a separate preamp and power amp. The master volume for each channel controls the output of the preamp, which goes directly into the power amp. In this case, the power amp volume is always turned up at max. The issue is that the FX loop happens after the preamp, so there is no separate volume control after that point. Because of this, anything that goes into the FX loop will come out at full volume, including any noise that your FX may generate.

Guitar FX do generate a certain amount of noise, but usually we don't notice because the level of everything else is loud enough to cover it up. When you have it going into the power amp directly, though, that noise will be turned up as loud as possible. If you are playing your amp loudly you might not notice, because the guitar sound will be so much louder, but if you have it turned down to comfortable levels, the noise from your pedals can be significant.

The only good solution that I have ever heard for this (other than turning up your amp to max volumes to drown out the noise) is to put a volume control at the end of the loop, so that you can turn your channel volumes up higher, and then reduce the overall volume at the end of the loop. This will allow you to turn down the noise from the pedals in the loop to a point where it is below the level of the guitar, and then you have the ability to adjust your overall volume right before it hits the power amp.

 

[ratter]

The only thing I've used in my loop so far is a TC G-Sharp and I didn't notice any hiss at any volume. Certainly not anything objectionable.

 

[markblasco]

Another thing I would do to test this, since MrSmitty has a Mark V, would be this: Take your Mark V and turn up the final master volume all the way to 10, and if the FX loop has a separate volume control, turn that all the way up too. Then, turn your individual channel volumes down so that you are at a comfortable low level in volume. See if you have the same sort of noise. Disclaimer: I don't own and have never used a Mark V, so I don't know how it is structured, so this may not work, or may blow up the world, but my guess is that with the final master volume all of the way up, and any FX loop volume control turned all of the way up, you will have it setup similarly to how the mini rectifier is setup.

 

[MrSmitty]

I appreciate the suggestions and input so far on this issue. I've owned 3 other different Mesa amps and have run the same G-Major effects unit through all of them...never had serious "hissing" problems. The F-50 had a very, very slight hiss but hardly noticeable at gig levels.

This is an issue MESA needs to figure out. I shouldn't have to build a special volume box for the FX, or subject my Mark V to cruel and unusual testing in order to fix the Mini Rec.

 

[markblasco]

I appreciate the suggestions and input so far on this issue. I've owned 3 other different Mesa amps and have run the same G-Major effects unit through all of them...never had serious "hissing" problems. The F-50 had a very, very slight hiss but hardly noticeable at gig levels.

This is an issue MESA needs to figure out. I shouldn't have to build a special volume box for the FX, or subject my Mark V to cruel and unusual testing in order to fix the Mini Rec.

Well, I'll make one more observation and then leave it alone, since without being there to actually see and hear what's going on, I'm out of good guesses. I had the F-30 (which I'm assuming has the same FX Loop design as the F50), and due to the parallel FX loop, there was a volume control for the FX return on the back. When I modified mine to have a serial loop instead, I had the same situation as I have with the mini rectifier (anything going into the FX loop was being sent to the power amp at full volume), and had to have a volume attenuation in the loop. Before the mod, when I tried using delays in the loop, I ended up turning down the loop mix control, which had the same effect of turning down the noise.

So, I guess my last thought is that if you turn your mini rectifier up to a full gigging volume, and the noise from the g major is not noticeable underneath the noisefloor of the preamps, than it sounds to me like everything is working correctly, and it is just an issue of the amp design (since turning down the preamp volumes will remove the noise from the preamps itself, but not have any effect on the noise from things in the loop). If you are saying that the noise you are hearing is so loud that it is noticeable even at gigging levels, than I would agree that there is something definitely amiss.

Do you have a place near you that sells mesa gear? Maybe you could take your setup into a local Guitar Center or similar store and see if another mini rectifier has the same issue?

 

[freebob]

solution for you guys:
it's, as we thought a ground loop problem.
on a Line 6 forum somebody posted the solution.
you will find it at the end of this article.
http://www.rjmmusic.com/wp/2011/06/07/the-4-cable-method-and-its-potential-ground-loop-problem/

... I was going to sell the little monster and.. guess what... I keep it

 

[antikue]

Very nice you found a solution

I'll hijack the thread for a bit, since it's close enough for my problem. I haven't found a conclusive answer to this, but do your Mini Rectos leak a very high presence distortion through to the cabinet? I mean, with the channel master down to 0 I get a 'bedroom level' sound out of the amp. No hiss or interference noise of any kind - just the guitar. The vintage gain mode does this at a whisper quiet, but audible, level. The modern however comes through very clearly and quite loud to be honest. I need to really turn the amp up to drown the fizz. At that level it's quite unusable in an apartment setting, really. The fizzy distorted signal comes through with or without the FX loop engaged, and placing an EQ in the loop with the level sliders all the way down does nothing whatsoever to attenuate the fizz.

An actual attenuator does reduce the volume, but I needed to turn the MiniMASS 50 I had to very high levels of attenuation to get the modern mode fizz down to the unattenuated vintage gain level. Needless to say at that point the tone was utter mush.

So - is it normal? Thanks folks!

 

[antikue]

So - is it normal? Thanks folks!

Guess it is then

ENGL here I come

 

[KiwiJoe]

Very nice you found a solution

I'll hijack the thread for a bit, since it's close enough for my problem. I haven't found a conclusive answer to this, but do your Mini Rectos leak a very high presence distortion through to the cabinet? I mean, with the channel master down to 0 I get a 'bedroom level' sound out of the amp. No hiss or interference noise of any kind - just the guitar. The vintage gain mode does this at a whisper quiet, but audible, level. The modern however comes through very clearly and quite loud to be honest. I need to really turn the amp up to drown the fizz. At that level it's quite unusable in an apartment setting, really. The fizzy distorted signal comes through with or without the FX loop engaged, and placing an EQ in the loop with the level sliders all the way down does nothing whatsoever to attenuate the fizz.

An actual attenuator does reduce the volume, but I needed to turn the MiniMASS 50 I had to very high levels of attenuation to get the modern mode fizz down to the unattenuated vintage gain level. Needless to say at that point the tone was utter mush.

So - is it normal? Thanks folks!

My Mini Rec produces no noise of any kind with the master volume at "0" on either channel, any setting.

 

[freebob]

It does, if your cables from fx loop run too near to the box. Then it humms, pretty loud, even putting volume to 0 still hummus. Solution: don't let cables run upon the box. That's it.