Zvex - Lo-Fi Loop Junky  [traced]

General documentation, gut shot, schematic links, ongoing circuit tracing, deep thoughts ... all about boutique stompboxes.
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Hides-His-Eyes
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Post by Hides-His-Eyes »

madbean wrote:I'll be releasing a project and PCB for the Mobius at some point. I've had a design done for quite some time, but it's not working as of yet. Once I finally get around to ironing it out, I'll post the project here (which will include PCB artwork, of course). My layout is quite a bit smaller, too.
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Post by oldgravity »

I just built up a Payback 1.0 with added pitch shift knob, lots of fun.

If you play very straight-forward music, for sure one of these is very limiting compared to a Boss unit or similar. If you actually like weirdness imparted to your recording, these answering machine chips are very nice indeed. The Payback transforms my DIY MIDI synth into something more like a Mellotron. I very much recommend this project to anybody into this kind of thing. Madbean, any plans to add vibrato to the Mobius project? And a sample rate/pitch/speed control (easily hacked)?

If you want more features in a DIY looper, check out the WTPA?. It's still for weird people, not jam band noodlers, but it's got a lot more going on.

A guy and I over at DIYSB are putting together a more modern-style digital looper project at the moment. If it materializes, I'll post it over here for your enjoyment. It'll start out very simple, but higher recording quality and more time than these ISD-based loopers, and the ability to overdub. Then I hope to do a really full-featured one, with continuous playback speed control, multiple simultaneous channels with their own controls, punch-in/replace/insert, reverse, etc.

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Post by oldgravity »

I also just built this:

https://www.diystompboxes.com/smfforum/ ... ic=86729.0

This is still no good for the pristine tone crowd (worse actually), but for the adventurous this is one of the most amazing DIY projects ever. It does all the stuff a commercial looper does, and some stuff that no Boss or EHX box would ever do.

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Post by madbean »

That's great! Are there any demos around for this behemoth? This looks like a terrific project.

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Post by oldgravity »

There are demos around if you search youtube for "wtpa" or "where's the party at sampler", but they're mostly being used in Daft Punk-style music: sample a measure of some funk track, then repeat it forever kind of stuff. None in an instrument looper context, but I will try to record some clips soon.

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Post by frequencycentral »

I've got 2 x Loop Junky(s) here at the moment, one from '02, one from '07. They seem to differ only in the stompswitches, the old one having DPDT, the newer one 3PDT. Should I post gutz? Anyone interested in revving this one?

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Post by ~arph »

You should have posted this tomorrow, looking at the previous posts dat :P
Of course we're interested, btw doesn't he have a new 'instant' lofi junkie out now?
or is that just like all his latest 'new' pedals, just trimmed down cheap china versions of products he already had.
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Post by Seiche »

frequencycentral wrote:I've got 2 x Loop Junky(s) here at the moment, one from '02, one from '07. They seem to differ only in the stompswitches, the old one having DPDT, the newer one 3PDT. Should I post gutz? Anyone interested in revving this one?
please do. afaik madbean has a pcb out for the lflj. don't know if it's a clone though or just an "inspired by".

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Post by Scruffie »

Seiche wrote:
frequencycentral wrote:I've got 2 x Loop Junky(s) here at the moment, one from '02, one from '07. They seem to differ only in the stompswitches, the old one having DPDT, the newer one 3PDT. Should I post gutz? Anyone interested in revving this one?
please do. afaik madbean has a pcb out for the lflj. don't know if it's a clone though or just an "inspired by".
It's an inspired by I beleive, I think the design was originally derived from the Mobius Trip looper before expansion... but he'd have to tell you that.

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Post by madbean »

Mine is a modded Mobius. I've never seen the Lo-Fi, so I am curious of course :)

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Post by drbob1 »

~arph wrote:You should have posted this tomorrow, looking at the previous posts dat :P
Of course we're interested, btw doesn't he have a new 'instant' lofi junkie out now?
or is that just like all his latest 'new' pedals, just trimmed down cheap china versions of products he already had.
I think this is just the signal processing without the looper.

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Post by rasta_maleek »

i´m interested too, and curious :P

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Post by ansil »

along time ago zach said that the circuit was really closely based on the ic's datasheet even using the pin input for external clocking. also there was a previous thread where again its a SHO booster in front of it. what i want to know is if you like crazy lofi stuff why not spend the 10 bucks on the premade radioshack recorder chip with the buttons and speaker already hooked up. put it in a box. it will loop as theres a led flash at the end of the cycle and you can simply tie that back into the play/stop button so the end of the recording will always trigger replay no matter the length. Tone God was helping me with a shift register idea to re trigger the ic when we both realized the led flashed at the end which could be used to re trigger the thing. a simple fet buffer works for driving the input of it. And it has plenty of signal output to drive itself. as always food for thought.

http://www.radioshack.com/product/index ... Id=2102855

oh and sorry its 11bucks now

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Post by Rockprocess »

Anybody have any ideas to add the ability to play the loop in reverse on Madbean's looper?

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Post by frequencycentral »

I found time to play with the 2 x Loop Junkies today. Had some fun recording a rhythm guitar loop on one, then recording both that and a bassline onto the second. It's also fun to record different loops on each pedal, play them together and they slowly slip out of sync. For the money, hmmmm, even the cheapest Boss RC has vastly more features..........

Best of all, it's fucking brilliant to breadboard with a looper running...........

@ Rockprocess. As the chips used are voice recorders, probably destined for answerphones and such, no reverse option is available. THe Boss loopers can do it though!

Anyways, I've got a lot of stuff going on this week, I'll post some gut shots next week.

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Post by madbean »

Yeah, dual loops are on my agenda for the next version of the Loophole. There's a lot of cool stuff to be done using them together, in series, parallel, etc.

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Post by treuze »

Hi i want to buil this effect, after many search i found this website : http://sounddiy.free.fr/AnalogLo-fiLooper.html
but there is no pcb layout on it... So with the help of google, i found those things:

Image

Image

Image

Image

Image

If someone could help me for redraw a new pcb layout with the pitch control mod and the tl071 in place of LM386, it will be very nice!
I also have a bill of material (in spanish but easy to understand):

R1, R2, R3, R4: 1K
R5: 0R
R6, R7, R9, R10, R11, R14: 100K
R8: 3M2
R12: 10K
R13: 180K
R15: 4K7
P1, P2, P3: potenciometros de 100Klog funcionando como resistencias variables (la pata del medio y la de un extremo van conectadas)
C1, C2, C12: 100uF
C3, C4, C6, C8: 150nF
C5, C9, C11, C13: 10uF
C7: 10nF
C10: 1uF
C14, C15, C16, C17, C18: 100nF
D1, D2, D3: 1N4148
LED1: led bicolor (como 228-5641 en http://www.amidata.es)
Transistor: BS170 (el que se usa en el millenium bypass)
Operacional (O.A.): TL074
Puertas XOR: 4070
Amplificador: LM386
Sampler: ISD25XX (2532 o 2560 recomendados)

In advance thanks for your replies! (sorry for my mistakes, i'm french and i'm not very good in english...)

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Post by xaxxop »

frequencycentral wrote: 31 Aug 2011, 23:10 I found time to play with the 2 x Loop Junkies today. Had some fun recording a rhythm guitar loop on one, then recording both that and a bassline onto the second. It's also fun to record different loops on each pedal, play them together and they slowly slip out of sync. For the money, hmmmm, even the cheapest Boss RC has vastly more features..........

Best of all, it's fucking brilliant to breadboard with a looper running...........

@ Rockprocess. As the chips used are voice recorders, probably destined for answerphones and such, no reverse option is available. THe Boss loopers can do it though!

Anyways, I've got a lot of stuff going on this week, I'll post some gut shots next week.
Hi, do you still have the pedals for sharing the guts? There are a few options for the with the same IC but I would like to know how to modulate the power to recreate that retro sound. Thanks

Leo
Leandro

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Post by ppluis0 »

Hi Leandro,

Frequencycentral as forum member has not appeared here for a long time so I think it will be difficult for someone to give you the information you require.

Cheers,
Jose

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