Two questions

I haven’t pulled the trigger on a Mod Duo yet, and I need two questions answered before I do:

1. What is the longest delay time available? I have searched the forum for any mention of this, but found nothing.

2. Is it possible to create feedback loops in the pedalboards? I browsed through all of the pedalboards posted over the past year and then some, but I haven’t seen any that route outputs back to the inputs of pedals earlier in the chain. This is an option on some late '90s/early '00s Alesis and TC Electronic rack effects, where you can have 8 delays, set all of their feedback to zero, but feed them in and out and back into each other and themselves in a crazy Frippian loop.

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Hi @ziggyzipgun,

I dunno the longest delay time but you do get complete signal freedom on the MOD UI, which allows you to create sidechains and feedback loops at will.

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Hello @ziggyzipgun,

This is a good question, but I hope I can answer it.
There are some BPM related delays that have (sub-) divisions in it (1/4, 1/4t, 1/4 dotted) and such like Bollie Delay.
There are some delays that are analog or digital that have delay times in milliseconds or seconds like Guitarix Digital Delay Stereo
and there are some that are modulated by LFO and such like
Rakarrack Echotron and MDA DubDelay,

Some delays with parameters:
RKR Arpie BPM Delay from 1 to 600 BPM, subdivision 1, 1/2, 1/4… and
RKR Echotron
Bollie Delay (see link above) 6BPM to 1000, Subdivision 1/4, 1/4T, 1/8…
Guitarix Digital Delay Stereo 24 to 360 BPM, dotted 1/2 ,1/2, 1/2t,…

MDA DubDelay with feedback saturation, 0ms to 7341 ms
Steve Harris Beta Reverse delay has 5 seconds, his delays a time of 10 seconds,
Infamous Stuck and Infamous Stuck Stacker have a delay/ release time of 3 seconds…

I hope this might be helpful to you!
Greetings and God bless, Marius


What a great answer! I learned a lot and it wasn’t even my question. Thank you for all the links and information.


feedback loops can be created a-plenty. I’ve done a few pedals that use them (mainly for doing regenerating octave delays).

The delay time thing will be moot once they add feedback control to the ‘sooperlooper’ pedal - then you can have minutes of delay, so long as you’re willing to tap start and stop rather than have a set tempo… (I think the longest ‘actual’ delay I’m using at the moment is about 8 seconds, but there may be options to stretch that in some of the RKR pedals… they run pretty deep :slight_smile:


Thanks to @ziggyzipgun, @dwek, @unbracketed and @solobasssteve,

someone had to sort out some infos about a vast multitude of effects we can choose from.
It ttook me about 15 minutes to get all delay pedals on a pedalboard and to copy resource pages here from their pedalboards pages. Someone might add ttheir behaviour in terms of real pedal counterparts,
For example the famous GxDuckDelay Mono and GxDuckDelay stereo are like the early TC Electronic flashback delays and such. If in the discussion part to the plugins someone posts what it sounds like or what she/he uses it for, searching for the right pedal plugin would be a piece of cake…
Maybe we could “pimp” up our plugin and pedalboard resources with this information.

Thanks to all developers that have poured into these delay(ed) lines of code.
Some commercial pedals have the option to pay for some sort of effect. This is an appreciation that directly goes to the developers instead of the marketing sector of those manufacturers, if someone wonders about effects for sale on the mod platform.
Hope that helps.

God bless, Marius


Like I said, I don’t own a Mod Duo (yet), but my main interest is having a pedal that’s more like a modular synth system - LFOs and ADSRs that can be routed to anything. Hell, someone could design a pedal that is just the pin matrix panel of an old EMS Synthi, that you would be able to route any pedals into. I want the pedals to interact with each other rather than just series or parallel chains - a quadrature LFO that you can link to all of your different modulation effects? Bring it!

With that said, I spent as much as a Mod Duo on a Lexicon PCM80 yesterday, so it’ll be a while before I’m on the market again. Over 25 years old and it has 24-bit/48kHz SPDIF i/o, balanced and unbalanced i/o… Mod needs to update their i/o to make it more future-proof.

I never thought of stacking delays after each other to extend delay time… That is genius! :star_struck:

On my old Alesis unit, I run multiple delays, and the feedback for each one is set to zero - if I want it to decay faster, I can adjust the gain of the return connection. I like to route them in a sort of figure-8 pattern, swapping the left and right channels and inverting the phase before they complete their loop. I still have a lot of experimenting to do with the delay times of each one, since I usually only have the first one in each channel actually connected to the outputs, so there’s a longer pause while the notes are running around through the rest of the loop before they get back to the beginning and can be heard. It works a lot like a multi-tap delay, but it preserves the rhythmic sequence and can actually sound a lot like a sequencer. Plus you can place pitch shifters and other effects anywhere in the loop.

So this piece of gear from 1995, which I paid $59 for from Music Go Round, is limited to 8 effects blocks, plus a couple envelopes and LFOs that can be set to control any parameter (it also has optical i/o, SPDIF i/o, unbalanced and balanced i/o). I get that the Mod Duo is limited only by processing power, but most of the effects seem to be trying to replicate existing standalone effects, rather than serving as functions that can be linked together to create new effects. I already own a Line 6 POD HD500X, which has stompboxes aplenty and fairly convincing amp models that were created by an entire R&D department that had access to time, money, and hands-on experience with the equipment they were trying to replicate. True, the routing options are limited, but still fairly flexible. It does have SPDIF i/o, unbalanced and balanced i/o, and doubles as a stereo DI box and a Midi foot controller. Oh, and it cost less than a Mod Duo - especially now, but even 5 years ago when it was released.

I guess my rambling point is, the Mod Duo has seemingly limitless potential, but nearly all of it remains untapped. It is not unreasonably priced, but it should have a few more features that would make it very useful in the studio. I do no look forward to the day when they allow users to charge money for the effects - this could easily flood the site with mediocre models from folks looking to make an easy buck, just like all of the extremely stupid apps you can download for 99¢. Mediocre models will discourage new users and scare away future ones, which will discourage the company from releasing an updated unit with hardware features that weren’t available on the POD 2.0 when it came out in 2000.

Hello @ziggyzipgun,

nice to hear you invested in a Lexicon PCM80. Those oldies but goodies still sound amazing especially if it is a multi effects processor. I have a Lexicon LXP15 whose 2 inverted gray encoders I have to replace with non-inverted ones.

In case of fiddling with hardware might look for the Mod Duo X as it has CV input and output as well as analogue stereo I/O. This would be the way I would go.
But as you point out regarding the development of the Line6 Pod HD500X, I think the mod developers (and users!) team has still a lot to do replicating and inventing (combinations of) effects that are completely new as well as old ones.
If we manage to invent some weird but usable effects out of plenty possibilities we got at hand we can push moddevices definitely forward.

In case of playing with modular synth parts inside the Mod Duo or Mod Duo X.
Aurelien Leblond has ported the whole [Alsa Modular Synth package]( to lv2 so you can build your own synthesizer parts within.
These are 66 different modules including oscillators, analog memory,
Bitgrinder, CV sources, Delay, Dynamic Waves Oscillators with 4 to 8 voices,
Envelope with Delay, Hold and timescale, Percussive Envelope, VCFs, Moog LPF,
FFT vocoder, Hysteresis, Inverter,
LFO with frequency, phi, BPM Tempo and waveform, a multiphase LFO,
2,4,and 8 channel mixer, Ring modulator, Slew Limiter, 8 to 32 step sequencers,
and such to name a few…

I am just a german user who wants to explore the capabilities of the mod duo family to the max and to program pedalboards and effect combinations that others may use or change to their benefit. In my view the mod duo would benefit from a digital I/O in form of SP/DIF cinch or ADAT Toslink sort of connector or USB I/O, I even could imagine an AES67 “Audio over IP” or AVB version, if that was possible. I know there is an implementation of an audio network within linux. But these questions would be better sorted out in another thread that covers future vision. Sorry if the last part of my answer got a little too off-topic…

We all only can give our input, but I think this will be heard.
God bless, Marius


I do like that the Mod Duo X has some CV i/o, but I think its current price is a bit high. I know it’s hard to compare it to other products on the market, because there really isn’t anything similar, but in terms of manufacturing costs and the cost of the hardware components, it could be much cheaper. That would put it in the hands of more people, and their collective brainpower would lead to more interesting effects. Once they move those models to a marketplace, it will be overrun with garbage.

The same can be said for many successful products (and services) on the market.

Today, you can take MOD’s open source software and install onto basically anything that will run Linux: Raspberry Pi, Beagle Bone, a Meerkat, etc. Pair it with an audio interface and you have a DIY Duo (not including hours of software install, config, debugging, and/or soldering)

Have you seen

hard to compare it to other products on the market, because there really isn’t anything similar,

For anyone who doesn’t have time or motivation to hand-assemble their own custom audio computer the Duo is a pretty sweet deal. I’m a 40-ish software professional and I know what my hourly time is worth (in life and business). Even though the idea of building my own world-dominating rig sounds like a fun and interesting challenge, it would take away SO MUCH time from a few things I’m very passionate about right now.

As a guitarist and budding multi-instrumentalist, the Duo offers me a huge amount of creative potential and convenience. Compared to the fanciest multi-effect pedals on the market, the Duo can provide the same types of functionality, but is also massively hackable. Many things are possible with the Duo that would be cost prohibitive or physically difficult (for example, dozens of pedals in parallel, arbirtrary feedback loops) As more techies come into the community, l’m confident we’ll see community contributed features and tools.

I see it more as buying into a platform and community. There are some rough edges and unanswered questions. They’re trying to do something new and innovative; not everyone will be pleased.

Good luck and enjoy the music!

  • Brian

I’ve been having trouble creating feedback loops where the audio of the Mod Duo X will just stop entirely - even before a crazy feedback loop has started.

For example:

audio in > effect 1 > master
> volume mod % > effect 1

IE: the signal from effect 1 is being routed to the master and also to a volume effect and then a percentage of that is routed back into the effect. Controlling the knob will control the amount of feedback. It will do feedback but it’s inconsistent and most times stops all audio and requires a restart.

Any ideas?

I never tried to do a feedback loop inside the ModDuo, but i think you will at least need to add an additional limiter to the loop. This will make sure the overall volume does not exceed the Duos safety limits.
In an analog setup this limit is given by the battery voltage of the circuits, but since the Mod is all software, the output values practically go to infinity.

As @CharlyRebell mentioned, you may be triggering the safety limits coded on the device. Using a limiter in the feedback may be wise. Let us know if that works out.

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Thanks @CharlyRebell & @Jon - I’ll try placing a limiter there and see what happens.

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hi @jon are there any ways to bypass or extend the safety limits?