Looper with overdub/sound-on-sound? Payback x2?

[Taylor]

I have been searching for a looper project that can do overdubs like pretty much all commercial loopers can. I realize that this is the sort of thing easily done with DSP, but very difficult otherwise. Even recognizing that, I'm curious about how to do it anyway.

It seems like the problem is that the recorder chips that the DIY loopers are based on cannot record and play at the same time. So, wouldn't it be possible to do this with 2 recorder chips, which keep swapping record and play duty?

[Processaurus]

How about a two track lo fi looper, that the logic for the record/play of the 2nd looper could somehow cleverly be synced together in a fashion were one could go 2x, 3x, 4x the length of the 1st one?  I've been liking that functionality in the loop machine in Guitar Rig.

With the loopers in parallel rather than in series you'd get the same fidelity on each of the two tracks.  Plus with them separate you could run them to different outputs, or different effects loops.

[The Tone God]

There are problems with both ideas.

The problem with feeding one into the other then flipping the ICs is that with each layer the earlier layers start loosing definition. I found after about three layers the first layer starts getting lost. It really doesn't work well. Noise builds up too.

Ok so have two ISDs in parallel. Well now the problem is keeping the ISDs in sync. Their internal clocks vary a fair amount. I got them pretty close to each other but after a few minutes you can start to hear them fall out of sync as the small time differences add up.

I really don't think there is a reliable way to do S-O-S with these ICs.

Andrew

[Taylor]

So, M'Lord, are there any other IC families worth looking at? Is this one of those noble but impossible pursuits like making the roommate switch? Even a kludge solution would be of interest to me.

[caress]

i think parallel would be ok if you don't need the loops to be in time... i do a ton of ambient/washy/sound loops on my DL6 and i could care less if they are together or not, actually it would be nice if they DID go out of sync... more variety!    hmmmmmm new project time

[Cliff Schecht]

I'm more interested in a digital looper, something based off of a microprocessor interfaced to external memory (SRAM?). A micro like the MSP430FG4250 would do the job well and not break the bank. I've never even tried to interface a micro to external memory, however, so I'm just kicking around ideas until I can pull my head out of the dirt. With SRAM, you could get the effect to do as many overdubs as you want until you fill up the memory. With flash, you could even save your favorite loops! Pipe dream?

Not that I have time to take on a project like this personally (it doesn't help that my programming kung-fu is weak), but it'd be cool to develop as a community maybe. I understand the purpose of the Payback effect and think it's cool, but let's not push the idea past what it's really capable of doing. Instead of basing a design off of the BBD chips, go digital and get the sound of a good digital looper for cheap!

[Taylor]

Well, I'm sure we'd all like to do that, but it is far beyond my abilities, and I suspect those of most on this forum, so it's not really an option unless somebody wants to be generous and do the coding for us.

Perhaps we could convince PAIA to do a digital looper kit, with preprogrammed microprocessor? If only we knew some one involved with them...

[Cliff Schecht]

*looks the other way*

I'll mention it to the boss man. It would be a while though, a product like this doesn't happen overnight .

Or I could instead work with Andrew (or whomever else can program this sort of deal) to get something steamed out here. While I already have a Boss RC-2 looper, I'd love to do a DIY version on the cheap. It's not that hard to implement something like this, the real bitch is finding hardware that's cheap enough but still sounds good. That's why I pointed to that particular MSP, it's got a 16-bit A/d and 12-bit D/A (might be pushing my luck at this low of a bit-rate, but 3 V with a 12-bit DAC is .7mV/bit), 2 internal op amps (input and output filters), LCD driver (cool gimme?), and enough flash to cover the software. The thing I'm not sure about is how to interface to external memory, I've never tried it on an MSP!

[The Tone God]

I said in the other thread that Payback v2.x is IMHO the epitome of this technology. That is not because the Payback design is the best, although I doubt you can make it any simpler without sacrificing any of the core feature set, the major limitation is the ISD storage. I think Nuvotron has hit the maximum capabilities of their direct storage technology. I say this because I have not seen them increase the sampling rate or cutoff frequency in any of their newer designs and they already have very long memory times so adding anymore is just increasing the price to the point of not being competitive with digital options. I think the final sign that this is true is that Nuvotron's newest ISDs are digital.

I agree with Cliff. The next logical step is to go digital. Oh no the "D" word! Do I have some ideas for DIY friendly digital loopers ? Well of course I do. Perhaps Payback v3.x ? I would love to kick my RC-2 off the board with a DIY option.

Andrew

[liddokun]

Any updates? Or has it been put on the backburner for now.

[Taylor]

Since Payback 2.0 hasn't been released yet, I'd guess that the all-digital version is but a gleam is TTG's eye at this point.

[Strategy]

This is what you guys want; the pcb's might be sold out - I am working on one now. This guy is sure to issue followup projects so watch this one.

www.narrat1ve.com

It's not a pedal, but it could be with a cheap MIDI foot controller. It's a super specced out 8bit sampler - like an SK1 from another planet on steroids. Taylor, this is likely lower bandwidth than you are hoping for but this project might be up your alley- it's called the Where's The Party At? sampler

- Strategy

[Taylor]

That thing is pretty cool. I will have to check it out more, but I like the idea of granular reconstruction, etc. It seems like it could be a very fun thing for making some weird music, which I like. I'm guessing, based on the look and the name, that it's aimed at people doing Daft Punk/Justice kind of stuff, or maybe Dan Deacon or something, not really my kind of thing, but it does look versatile enough that it could be used for other structures of music.

That said, and again, this is from a fairly cursory look so I could be wrong, it doesn't look like it's able to record and playback at the same time, which really is "where the party is at" for an instrument looper. You can do neat things with a sampler and a guitar/bass/keyboard, but a real looper is all about laying down a part, then playing it back while you record another layer, and so on. I don't think the WTPA can do this sort of thing. Low bandwidth is totally fine with me, but I do want overdubs.

Thanks for that link, I'm really interested in it. Please let us know your thoughts (and maybe post some pictures) when you get yours finished.

Edit: Ok, found some videos of the WTPA. It is very lofi and extremely aliased. Sounds cool for some rhythmic stuff, but for recording harmonic instruments, it seems a little too crunchy for my taste.


I've been thinking (since this morning   ) that a digital looper would be an excellent DIY project that doesn't exist yet. I would be very interested in working with someone with coding skills to make a project for the DIY community. I could get some pro doublesided PCBs made up like the Gristleizer project we've got going right now, and do pre-programmed chips. I will look into this, but if anybody out there with coding skills is interested, PM me to get something going.

[Strategy]

Taylor,
re: aliasing, a lot of people are using WTPA at its most aliased setting, so don't believe it until you hear all the demos. It should be similar in character tonally to the Akai S-612 (the "electro-harmonix akai" sampler that kicked offAkai's long sampler line, an awesome piece of gear.) Again, it's probably lower bandwidth than you want but I think a lot of those demos illustrate the machine set to lower bit rates to illustrate its realtime bit reduction capabilities.

re: live overdubbing and rec/playback, yes it does do this. It is mean to replace, for example, a Line 6 green delay looper, if you want, or be more SK-1 like.

re: music style, most of the people building it seem to be beatheads but I would not let that stop you at all, it should be friendly to whatever you throw in there. I do music ranging from club music to ambient and noise music, playing live rhodes, organ, bass guitar in bands, etc. etc. - a tool like this should be very versatile. Being open to MIDI is key with the WTPA in using it to its fullest capabilities.

re: a DIY sampler, I think this would be a great DIY project, one that will be important to take on. Sadly RAM and microcontrollers and stuff- I have no abilities in these areas. If you consider that the Manecolooper (a boutique looper series from South America in case you aren't familiar with it) are based on the original EHX 16-Second Delay circuit (If memory serves) then maybe cloning digital loopers of bygone days is another option, provided that chips are either plentiful or easily replaced (?) One of the problems with the ISD projects is the rapid rate of obsolescence in the IC's.

- Strategy

[sean k]

I know it's not quite looper but I'd been musing a few weeks ago about using the PT2399 in a way that allows you to get the first input just going round in a loop using the feedback while your original signal bypasses the PT2399. It completely baffled me because I'm not up on logic I's at all but it was basically about using the signal out from the 2399 to go through a detector of some sort that would then switch your input to bypass but be mixing with the delayed output.

I kinda think that using a set of logic chips and various routing would most probably acheive a reasonably usable looper especially if you daisy chained 2399's with higher sample rates to acheive a longer delay time or loop length. Then all you need is the ability to add as you go and, most importantly, the ability to drop the lot, dive the feedback to zero, to start again.

The question is will 4 x 2399's at 250ms create 1 second of relatively glitch free loop and how many times would it go round before it turns to mush?

[Taylor]

You can do that with a stock Echo Base. With the "tails" bypass on, when you turn up the feedback, it'll keep going without entering new material to the loop. The Echo Base uses diodes in the feedback loop to control runaway feedback, and these make unity repeats get compressed and distorted of course, but if you took them out and kept an eye on levels, or added a limiter in the fbk loop, you'd have what you're talking about.

A single PT2399 can do a second with a little bit of dirt, and up to 10 seconds if you let it get really bit crushed and noisy. If all you wanted was 1 second clean, you could do it with 2 PT2399s. 4 could get you into 2 seconds with relative cleanliness. Then again, my clean is your distorted maybe...

[solderman]

Hi
I've been thinking of building one of those as well. I have an idée to use ready made building blocks of several (2 or 3) ready built MP3 code/decode units and use one foot controlled and programmed PIC controller and switches to handle the transport and rec on-off  and then mix all of them together mono or in stereo.

Stupid or ...??
 

[Taylor]

For those that don't check the digital forum:

http://www.diystompboxes.com/smfforum/index.php?topic=80036.0

[sean k]

Well thankyou Taylor, to think that it's been right there under my nose... or foot actually. My echobase is as the schematic but it always stays on, which I suppose is some resistor around the transistor that fires the 4066, so I haven't been able to turn it off, as it were, and see that tails switch do as you say... and I'd like to.

I'm planning a rebuild of the echobase enclosure so I can have the feedback and speed operated as foot treadle pedals, like a volume or wha, so I'll go over the circuit when I do that and see if I can't get it working as it's supposed to. With the foot pedals and the echobase acting as it should it sounds like I'll be able to do exactly as I proposed