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Help Moog Model D & EHX Little Big Muff

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Help Moog Model D & EHX Little Big Muff

Postby trash116 » Fri Feb 07, 2020 9:53 pm

Hi there,

Wondered if someone could help me, i've done some pre-reading on this but i'm still abit confused.

I've got an issue when i've tried to run my synth (Moog Model D reissue) into a guitar pedal (EHX Little Big Muff) then into my audio interface (RME Fireface 802). I'm connecting to one of the inputs with Mic/Instrument preamps on the front.

When i run the above set up, the sound is very quiet when playing through my DAW and not clear, when i'm not playing there the signal isn't quiet - there is quite a hum.

I've not tried distortion pedal before - the only other pedal i've got is a reverb pedal (eventide) and that works fine when connected the same way.

I'm sure i'm doing something very obviously wrong - any help would be appreciated.
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Re: Help Moog Model D & EHX Little Big Muff

Postby Eddy Deegan » Sat Feb 08, 2020 12:51 am

As nobody else has answered yet, I'm going to go out on a limb. I'm a keyboard man, not a guitar man and I know next to nothing about electronics but I've seen similar questions in the past.

The manual for the Little Big Muff says:

manual wrote:The input impedance presented at the Input Jack is 130 kohms. The output impedance at the Output Jack is 10 kohms.

...

To achieve its long sustain, the Big Muff Pi has very high maximum gain. This requires that both the pickups and cables be well shielded and properly grounded to avoid excessive hum when high sustain control settings are used.


I'm way out of my comfort zone here, so please don't take this as 'the solution' but as the Muff is a guitar pedal I think it expects an input signal at a significantly lower level than the Model D is giving it.

Its output is also likely at a level suitable for further guitar pedals in the chain (such as a compressor) or a guitar amp which expects an input on that lower level, so if you're plugging it directly into a line level (think synth) input which expects a stronger signal then that would explain the quietness you are hearing.

I also think the solution may lie in a DI box of some kind to match the levels, although I can't provide the details. Hopefully that helps in some way, and hopefully someone who knows more about this than I do can help further.

Two links I grubbed up while trying to find a clearer answer, in case you get more clarity from them than I did:

https://www.soundonsound.com/techniques ... -impedance

https://recordmixandmaster.com/2010-02- ... difference
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Re: Help Moog Model D & EHX Little Big Muff

Postby resistorman » Sat Feb 08, 2020 4:11 am

I’m not being snarky because I’ve done it myself... make sure the ins and outs are properly connected. I once wrestled with a dishwashing machine all afternoon only to realize that it had been wired into a wall switch which was off.
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Re: Help Moog Model D & EHX Little Big Muff

Postby IAA » Sat Feb 08, 2020 8:37 am

Which output from the Moog are you using.
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Re: Help Moog Model D & EHX Little Big Muff

Postby Hugh Robjohns » Sat Feb 08, 2020 10:18 am

trash116 wrote:I've got an issue when i've tried to run my synth (Moog Model D reissue) into a guitar pedal (EHX Little Big Muff) then into my audio interface (RME Fireface 802). I'm connecting to one of the inputs with Mic/Instrument preamps on the front.

There's no reason in principle why this shouldn't work...

Checking the basics first though, it would help if you could confirm what kinds of cables you're using... I'm assuming you're using standard (mono, unbalanced) instrument cables (TS jack-jack cables). If you're using balanced cables with TRS plugs, all bets are off!

When i run the above set up, the sound is very quiet when playing through my DAW and not clear, when i'm not playing there the signal isn't quiet - there is quite a hum. ... the only other pedal i've got is a reverb pedal (eventide) and that works fine when connected the same way.

If it works fine with the synth plugged straight into the interface, and fine with the synth plugged into the Eventide reverb pedal which is then plugged into the interface... then the problem can't be with the synth, or the wiring, or the interface... so it must just be the new Muff pedal that's causing the problem.

But just to be sure... please do check again that all the cables you're using are good, because a broken cable is by far the most likely reason for the problems you describe.

Distortion pedals like this have a lot of gain, which means they will amplify low level hums at the input which you might not otherwise notice with the pedal bypassed. And they have an output volume knob, so if that was turned down the output would be low level... but then so too would be any amplified hum...

So the fact that the Big Muff pedal's signal is very quiet but it's loudly hummy at the same time suggests to me that the pedal is either broken in some way, or you've plugged it up the wrong way around (input to output socket, and vice versa)!

If you're sure you've connected it up correctly, 'hummy' implies a problem with a missing earth connection -- which would also result in a low level signal -- so that points at maybe a broken or corroded input or output socket, or a plug not fully inserted, or the internal wiring may have come adrift somewhere.

But... it would pay to test if the pedal works properly in other situations? Have you tried it elsewhere with different equipment? Do you have a guitarist friend who could check it out? And are you sure the battery is okay?
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Re: Help Moog Model D & EHX Little Big Muff

Postby BillB » Sat Feb 08, 2020 11:39 am

A surgical analysis there from Dr Hugh. Do exactly what the Dr says then report back with any further symptoms .
:D
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Re: Help Moog Model D & EHX Little Big Muff

Postby Arpangel » Sun Feb 09, 2020 10:34 am

BillB wrote:A surgical analysis there from Dr Hugh. Do exactly what the Dr says then report back with any further symptoms .
:D

Yes, but I also think it’s a lead issue, I had a Mini and used all sorts of pedals plugged into line inputs with no problems. Make sure you use unbalanced cables, as balanced cables have given me issues in the past, just worth trying. Keep the level down on the Moog, it is quite hot, and can easily overload pedals, or use the alternative low output if that doesn’t work.
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Re: Help Moog Model D & EHX Little Big Muff

Postby Wonks » Mon Feb 10, 2020 8:01 am

The pedal is true bypass, so in bypass mode, the signal should be going straight through as if the pedal wasn't there.

So as has been said, use unbalanced TS jack leads. The pedal won't work properly if you use TRS jacks.

First plug the Moog directly in to the RME using one of the TS leads. Hopefully you should get a clear noise-free signal. Repeat this with the other TS lead. If both give you a good signal, then the leads are fine.

Now plug the Big Muff in, but keep it in bypass. You should be getting the same level and quality of signal as with a single lead. If not, there is something wrong with the pedal.

Now turn the Big Muff on. It is a guitar fuzz pedal and even with the sustain (gain) control at minimum, you will get some fuzz sound. This means that the signal is already being clipped, and the hotter signal from a synth (compared to a guitar) means that you'll get even more distortion. It also means that a hotter input signal won't give you a louder output signal, you have to use the pedal's volume control for that. To get the output up to a strong level, you'll need a lot of that volume.

As has been said, fuzz pedals are inherently noisy beasts. Any overdrive, distortion or fuzz pedal will create noise, so you can't expect an output with no hiss when you aren't playing a note. A fuzz pedal like the Big Muff is probably the worst for this, simply because you can't reduce the drive level to get a near-clean output signal. You'll really need to use a noise gate with it to get clean silences. Guitarists often do.

I'd also try it with a much cleaner drive pedal, maybe one based on a Klon Centaur, which can (on guitar) be used as a clean boost, as well as providing some medium level overdrive with the gain turned up. Or maybe a distortion pedal like the Xotic SL, which can be powered by 18v rather than 9v for greater headroom and a bit less noise.
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Re: Help Moog Model D & EHX Little Big Muff

Postby The Elf » Mon Feb 10, 2020 10:49 am

Or run the whole shebang via an ART Cleanbox Pro, which addresses all these problems at a stroke.
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Re: Help Moog Model D & EHX Little Big Muff

Postby Wonks » Mon Feb 10, 2020 11:52 am

The Elf wrote:Or run the whole shebang via an ART Cleanbox Pro, which addresses all these problems at a stroke.
It's not going to make a Big Muff hiss-free!!
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Re: Help Moog Model D & EHX Little Big Muff

Postby The Elf » Mon Feb 10, 2020 11:55 am

It will make it give of its best. I also use a Big Muff with synths and you have to live with its noise - it is what it is.

The Cleanbox will at least allow some manipulation of ingoing and outgoing levels, giving the best chance of something meaningful.


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Re: Help Moog Model D & EHX Little Big Muff

Postby Wonks » Mon Feb 10, 2020 12:24 pm

It was just that you said 'cure all your problems', and as one of the OP's problems was noise,...
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Re: Help Moog Model D & EHX Little Big Muff

Postby The Elf » Mon Feb 10, 2020 12:25 pm

It’s as good as it gets - the rest is just not curable.


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Re: Help Moog Model D & EHX Little Big Muff

Postby Hugh Robjohns » Mon Feb 10, 2020 12:36 pm

Hopefully the OP has already found and fixed the cause of his problems, as he hasn't been back.
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Re: Help Moog Model D & EHX Little Big Muff

Postby trash116 » Tue Feb 11, 2020 9:19 am

Hi Everyone,

Many thanks for all the advice - really appreciated ... some of it was very thorough advice so thank you.

I followed most of the advice... and went back to basics - checked the pedal with my guitar and amp, checked leads with moog, checked type of leads, and took more time in connecting.

Some of the points raised made me think. I've now got it working, i used unbalanced leads from the low output on the moog, into one of the front panel pre-amp inputs on the rme interface, i increased the gain on the preamp. I did get a more audible/louder signal into my DAW this time - i think it may have been as simple as me not dialling in enough gain of the preamp.

It's still very noisy, quite a hum when not playing - but looking through comments here and elsewhere i'm guessing thats the nature of the big muff on the synth. I love it on my guitar, but in all honesty im struggling to dial in a sound i like - i might need to spend more time on it.... but it's abit noisy and seems abit difficult to get anything other than quite a wild sound out of it --- but that might just be me.

Somebody else suggested i plug the moog into a reamp box, they specifically recommended the Radial ProRMP Studio Reamper. Would anybody on here suggest that is a neccessary step?

Im not sure i want to spend too much doing this, being really honest i only tried it as the big muff was lying around.

Once again, massive thanks for all the replies
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Re: Help Moog Model D & EHX Little Big Muff

Postby Hugh Robjohns » Tue Feb 11, 2020 9:37 am

Thanks for getting back to us, and glad you've made progress.

There will always be some electronic hiss noise when using a high-gain process like a distortion pedal, but there really shouldn't be much if any hum. If there is, I suspect you either have one or more ground-loops in your system, or your synth is lacking a ground altogether.

An easy and quick way to prove whether it's a ground-loop would be to use a DI box to connect your synth/pedal to a mic input on the interface, making sure to use the ground-lift switch on the DI box (and use battery power in the pedal). If that configuration is hum free you have a ground-loop between the synth and interface... and there are a variety of ways of curing that in a more convenient way which we can discuss if it turns out to be necessary.

If you still have hums, then it would be worthwhile adding a ground to the system. Another quick and easy test would be to take a standard guitar cable, and hold the tip of one end against something you know to be properly grounded (the mounting screw on a wall mains socket, for example), and the other against the sleeve of the unused output socket on the synth. In that way you'll be ensuring the complete system has a proper ground reference, and if that removes the hum we can discuss a more permanent solution.

H
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Re: Help Moog Model D & EHX Little Big Muff

Postby trash116 » Tue Feb 11, 2020 12:48 pm

Hi Hugh
Thanks for such a speedy reply, i've sent you a PM with abit of clarification.
Many thanks
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Re: Help Moog Model D & EHX Little Big Muff

Postby trash116 » Tue Feb 11, 2020 4:47 pm

Hi Everyone,

I just wanted to express my thanks to Hugh, i took the conversation offline from the forum topic so i could exchange a few PM's to get to the bottom of the problem.

I'm really grateful to everyone who posted with some insight and help, and particularly Hugh for spending the time reading my messages and helping me.

Looks like it is ground loop issue, which Hugh has suggested can be solved via soldering my own special cable - which i don't have the skill to do... so is best solved by a line-level isolating transformer or a DI box and connect that between the output of the Muff and the input of the interface. I am going to look into an ART DTI unit that Hugh has recommended.

Once again, thanks all - really amazed at the support and friendliness - think i will stick around on this forum going forward...

Marc
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Re: Help Moog Model D & EHX Little Big Muff

Postby Hugh Robjohns » Tue Feb 11, 2020 4:48 pm

:thumbup: :D
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Re: Help Moog Model D & EHX Little Big Muff

Postby The Elf » Tue Feb 11, 2020 4:53 pm

trash116 wrote:I am going to look into an ART DTI unit that Hugh has recommended.
Again I will suggest considering the ART Cleanbox Pro. It handles both sides of the pedal at once - in and out.
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