PT2399 looper? No?

[JimRayden]

Is there any way to use the PT2399 as a looper?

I'm thinking of a semi-looper kind of thing. It won't be recorded and looped with a footswitch (though tell me if it'd be possible), rather I was thinking of making it a 'running loop' with a synchronized metronome (a little tempo help to know where the loop ends). Several chips cascaded for more loopin' time.

-> push the switch
-> it starts ticking
-> just come in anywhere you like
-> once you've got one loop down, do other layers
-> press the switch to remove the input from chip
-> put the guitar down and go make yourself a dinner
-> return for a few solos

Will the gradually degrading quality and high end still be a problem if I'd leave the LPF's out of the feedback loop?

Well I thought I'd ask before purchasing one of those voice recorder chips... they're asking lethal prices for 'em here.

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Jimbo

[Barcode80]

buy a b*ss looper pedal. it does all this. or the di*itech jamman

http://www.musiciansfriend.com/home/navigation?q=boss+loop
http://www.musiciansfriend.com/product/DigiTech-JamMan-Looper-Pedal?sku=156600

the headache you are about to embark on, IMHO, is not worth the trouble and will likely not produce a functional unit like you are describing. I'm pretty sure a digital unit like this is about as easy as you are going to find to do that.

just my opinion though.

[JimRayden]

That certainly is NOT the DIY-spirit. Naughty!

Sure, there are also lots of distortions, phasers, fuzzes, amplifiers and anything out there. That doesn't stop us from building 'em.

So a looper needs a bit more time and dedication. So what! I'll drop the idea as soon as someone can prove it would be a total failure.

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Jimbo

[hank reynolds 3rd]

Maybe you could integrate something like that into the Tone Gods 'payback' sampler
that way ,the ISD25xx chip does the sampling,then you can feed it to a PT2399 after (w/feedback high maybe ,so the sample does this 'delay loop' thing ??) ,and repeat it for other delay chips at will???

[JimRayden]

Hmm, an interesing idea... but isn't the Payback already able to do several layers? I understand a delay chip is of no help here.

I was going for the delay loop because I just couldn't figure out a way for switch-based rec/play with that chip.

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Jimbo

[hank reynolds 3rd]

my bad

I thought it could only do one sample/loop at a time.....


Sam

[bioroids]

In my experience the signal will degrade quickly after a few repetitions. If you take out the LPF it will still degrade, and also have a lot of noise... I don't think the PT2399 is the chip for this job.

On the other hand:
Perhaps if you use a max sample time of 100ms you can adapt the filters to higer frequencies and still keep the noises out. The chip performs a lot better with short delay times. But 100ms of looping is really too little time, you'll have to cascade 5 or 6 chips at least for it to be useful.

Luck!

Miguel

[JimRayden]

Yeah I did presume I can't squeese the whole 800ms out. But six chips take up alot of real estate...

Could anyone take a guess where it degrades to? If there were infinite repetitions, what wound be the extremum? Random digital jibberish crackle? I can live with some bad-quality loopin' stuff as long as the notes and chords at least pronounce out...

Anyone?

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Jimbo

[rockgardenlove]

This would be a cool project, however I think I'll wait till you go through all the pain in debugging it before I start on it.   

[JimRayden]

This would be a cool project, however I think I'll wait till you go through all the pain in debugging it before I start on it.   

Well, it is about time I'd give something back to the community... I have quite a few projects in the bakery, now including a looper.

Gotta refill my stock of PT2399's... I guess three ain't 'nuf.

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Jimbo

[JimRayden]

Oh, and if you wondered where I got the obsession for loopers from, take a look at this.

http://www.youtube.com/watch?v=foXSXOAfB4U&mode=related&search=

This along with KT Tunstall performing "Black Horse and the Cherry Tree" live... Now that's my kinda woman.

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Jimbo

[aloupos]

Actually, if you want to cheat a little, this isn't such a hard task.  Radio Shack sell a "9v recording module".  Basically, a mic, mini speaker and a pc board.  costs $10 or something ...

http://www.radioshack.com/product/index.jsp?productId=2102855&cp=&pg=1&searchSort=TRUE&y=8&origkw=voice+recorder&kw=voice+recorder&x=9&s=A-StorePrice-RSK&parentPage=search

check it out.   I bought one of these a couple years ago for just this.  I ran into a problem, that at the time I didn't know how to solve.  After making the obvious connections (mic leads go to guitar in jack, speaker leads to out jack) your halfway there. 

with this you can hold the momentary switch, record a piece, release it, and press the play button and your piece will play back. 

Now, there is an LED that lights when the sample is finished (how nice for us).  The voltage from this can be connected to a mini relay, which closes the play switch.  Viola, a looper!  I think I needed to put a cap in there to slightly change the timing, otherwise the relay fired to quickly to loop and wouldn't trigger the loop again. 

Last problem.  You want to be able to record a loop, have it playing, and play over it, right?  Well, the board won't pass the signal from your guitar, and actually if you put it in series (guitar to board & straight to out), the board loads the guitar signal.  I tried a series of diods/caps ... but I think what you should use here is an op amp circuit.  have a look at splitter-blend from ROG.  This will also let you mix the loop signal with your raw guitar signal.  Should be pretty cool, actually!  I may build one this weekend.   

Anthony

[JimRayden]

Yeah, I did think of the little RS recorder dinghy. But I'm in europe and can't get my hands on one of those that easily. And as said, the real recorder chips are over 20 bucks over here.

Also, the RS recorder doesn't allow simultaneous playback and recording for that Les Paul Orchestra. I want layers!

I'll go with the 2399 first.

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Jimbo

[slacker]

Hmm, an interesing idea... but isn't the Payback already able to do several layers? I understand a delay chip is of no help here.

No the payback can't do layers non of the ISD "ansaphone" chips can. What the payback lets you do is have 2 separate loops that you can switch between.
I think unless you want lofi single loops, that the payback, dirty sampler, morpheus trip and the Zvex loop junkie can do you need to go properly digital. I think this is still outside the realm of DIY.

[JimRayden]

I think unless you want lofi single loops, that the payback, dirty sampler, morpheus trip and the Zvex loop junkie can do you need to go properly digital. I think this is still outside the realm of DIY.

So you're ruling out any chances of this projects succeeding? I don't care about the quality of the loops as long as the notes are separable and don't turn into digital jibberish cluster after a few loops.

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Jimbo

[The Tone God]

I have played around with sample loopers with sound on sound. It can be done but requires some extra circuitry. I used a uC to manage things. I suppose one could be made using discreet parts/gates but the control circuitry would get pretty large.

Andrew

[slacker]

So you're ruling out any chances of this projects succeeding?

Not at all, so long as you're not too bothered about the quality I think it's probably possible. I was really just pointing out that the chips people normally use for loopers can't do overdubbing so you wouldn't be able to use them, and if you wanted anything like the recording time they offer I think you'd need to go digital.
I've never experimented with PT2399s so I don't know if this is possible, but you might be able to do something like the hold mode on a Boss DD3. This basically records up to 800ms and then plays it back for as long as you hold the footswitch down. The quality doesn't degrade over time so I presume that it's keeping it in memory and simply replaying it rather than continually rerecording it.
The other thing you can do with a DD3 is set the repeat level just right and the regenerations stay at a constant volume, you can then layer more stuff over the top. It's tricky to get right but it works. The sound does degrade a lot but you can keep the loop playing for a few minutes.

[slacker]

I have played around with sample loopers with sound on sound.

I thought briefly about using a couple of the ISD chips to do multi layering, but soon realised it got very complicated very quickly and was probably beyond my limited skills.
I've just given in and ordered one of the new Boss RC2s 

[JimRayden]

The quality doesn't degrade over time so I presume that it's keeping it in memory and simply replaying it rather than continually rerecording it.

That's what I was wondering if the 2399 could be forced to do. Then decided it'd be quite impossible and stuck with the feedback idea.

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Jimbo

[bioroids]

That's what I was wondering if the 2399 could be forced to do. Then decided it'd be quite impossible and stuck with the feedback idea.

The internal looping cannot be done with the 2399, you are stuck with the feedback trick as you note. On my experience (delays stuff) the signal degrades pretty fast to a point you can't hear the original notes, but I haven't experimented with minimal filtering and low delay times. You could use a rebote delay pcb to start experimenting with this, and if you find the sound quility good enough, then move on to the control circuitry to make it a looper.

One good trick is to take the feedback directly from the OP output and apply the filtering just to the final output. That would be, feedback (for looping purposes) taken from pin 12 back to input low pass (at pin 16, with apropiate resistor). The output to be mixed taken from pin 14.

Luck

Miguel