ML5 Loop Passing sound when ‘off’

I have a slightly unique setup where I use 4 pedals in separate loops but the pedal in loop E (skipping D) doesn’t return to the looper but instead goes to a buffer then out to the mixing desk. The out of the ML5 goes to the input of the amp.

I’ve not done a full investigation and analysis however noted that when loops A and/or B are engaged I can hear an output through loop E through the PA (and the pedal pops when switching) even when it is not engaged. The sound is low and distorted but it’s there.

Any ideas why that may be?

Might be some crosstalk. What pedals are those in Loops A and B? Is it high gain?

Hi James, loop A is Rockett Archer, loop B JHS Muffuletta, Loop C is Bogner Blue and loop E (not D) is the Mooer Acoustikar.

Thanks for the info. When Loop C is engaged, there is no noise through Loop E? I’m guessing that there are some increased high frequencies (or maybe lower impedence) when Loop A and/or B are engaged, which lead to some crosstalk between signals. I will try to set something up later this week to take a look through my oscilloscope.

I’ll need to check when I’m home.

The Bogner Blue is run as a low gain/modded plexi type drive which may not be enough to trigger it. I’ll test this evening abs update.

Hi James,

I’ve done some further testing and these are my findings, which includes some odd results:

  1. Depending on the setup, all three drive pedals affect the acoustic send to the XLR out. There’s a definite grounding issue using this route as it seems the return is a source of grounding (and nullifying of audio). Without this the acoustic sim pedal is susceptible to noise when tapping or pressing of the switch.

  2. I tried a buffered pedal in place of the acoustic sim with exactly the same results.

  3. Placing a buffer (or pedal) in the vacant loop D, engaged didn’t resolve the issue, although the impact was slightly reduced.

  4. Placing a buffer with dual outputs - buffered and iso buffered outputs in loop 4 after the acoustic pedal made limited difference. The buffer returning to ground and iso out didn’t assist.

  5. Placing the buffer with dual outputs before the acoustic sim in loop 5 with the grounded buffer to the ML5 and iso to the acoustic sim resolves the issue but means the output goes to the ML5 output and therefore the amp input, which is what I’m trying to avoid.

The issue seems to be a problem of grounding, which appears to be resolved by the return to the ML5.

What I have t tried is running the buffer and acoustic sim in loop D with loop E engaged with nothing in it, which should mute the output, although it’s arguably a waste of a loop.

Hi James,

I don’t know if it’s classified as a fix but is certainly a viable work around, and strangely the Bogner Blue seems to suddenly be the culprit.

The work around is to have the acoustic sim send and return to loop D, providing the grounding. Then have the out of loop E as the output for the acoustic. A minute degree of cross talk remains but the pedals need to be cranked to hear it, which is a significantly improved place.

Edit, scrap that. Unfortunately it’s still happening. Bizarrely, including a buffer seems to exacerbate the issue, presumably as it’s trying to gain up the signal again?

I have now found a viable work around. :sweat_smile:

Out of loop D into the acoustic sim, into a dual/iso buffer. Output 1 goes to loop D return (grounding the signal) and the iso goes to the output/PA. Loop E mutes the remaining signal, avoiding the signal hitting the amp.

It’s not ideal as I lose a loop but it does work and it’s now silent. :blush:

An A/B switcher might be a better solution long term.

Feel like I’m spamming now but think I’ve diagnosed why I’m having an issue. This is from the FAQ’s on the ML5 confluence page:

When the loop is bypassed, the SEND loop is left floating (receiving signal) and the RETURN loop is connected to the ground (muted) with a 220r resistor.

This means the loop with the ‘send’ only (acoustic sim) is always open and receiving signal, because the mute (grounding) is on the loop return.

If I’m to remain using the ML5 I’ll need an AB switcher or alternative.

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Thanks for troubleshooting and for the info!

Actually, if that’s the case, what you can try is just running the ML5 backwards - so OUTPUT becomes INPUT, SEND becomes RETURN.
So your “SEND” will be muted when bypassed. There will be no effect on the sound as it’s all hard-wired relays in the ML5. Only thing is that the muted switching feature, if you are using it, will mute at the input instead of the output.

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Wow, I didn’t realise it would work in reverse - guess that’s the beauty of having no active circuitry and TBP.

Thank you, I’ll give that a go.

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Hi @James for awareness, I have resolved the noise issue using an input jack with the tip and sleeve jumpered together in the Loop return. This grounds the return and the ML5 is working in the normal manner.

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That’s a great solution - thanks for sharing!

Some really great information in here, y’all. I run my dry tube amp in its own ML5 loop, and have at times attempted to route in a Fulltone Tube Tape Echo in a similar fashion with similar noisy results. I’ll definitely be trying it again with the tip/sleeve solution.

And who knew the ML5 could run in reverse?? That is super cool, and gets me thinking…

If I’m not using any time based effects in the ML5, is there any reason switching the order would affect anything?

It depends on the use case. I managed to avoid reversing the ML5 by using the shorted jack, I’m not having any issues now.

If running in reverse, does the order go Loop E to Loop A? If so, might be a good opportunity to use the Global Parameter Updater…