Loophole , IC-change? ISD25xx 40sec Mod?

[PereatMundus]

Hey
I just built the loophole and I LOVE it.

I don't know why but its fidelity is far superior to what I've heard on youtube clips  
Spent over two hours  tweaking knobs and getting to know it with Isolated headphones.
Dunno if its a mix of pedals but it really didn't feel all that lo-fi to me.

But then I mostly..  used it in conjunction with about ten pedals..

and well I like the lo-fi and noisy sound.. so , irrelevant observation probably.

I wonder a bit how close the Loophole is to the tone gods Payback
http://tech.thetonegod.com/payback/payback.html

and If it could be modded to use the ISD25xx  IC chip instead for a full 40sec loop

What do you think?



Pinouts don't look all that different, and from what I can tell from the literature the ISD25xx is an updated version of the obsolete ISD1000A series.

The pins: differences

  ISD10xx                      ISD25xx
22: NC                             OVF
7:   NC                              A6
8:   NC                              A7
9:   A6                              A8
10:  A7                              A9

Oh, and searching ebay and the net you can get ISD10xx and ISD25xx chips  here and there for cheap.

Edit:
seems its a question of the mobius or payback style of DIY looper.
I dont really understand if the IC's are interchangable thou.
did see theToneGod sayes payback can only use ISD25xx chips etc. and yea the pinouts dont really match fully, but can the loophole (mobius based) use the 40s ISD25xx chips? *with pinout correction done ofcourse.

[JakeFuzz]

Yes you can use any chip in the ISD25xx(x) line. I used a 2560 in mine and it works flawlessly. With higher record times you get slightly lower sampling rates so the sound quality will drop. There are two extra function pins (i think they are called mode pins) that you have to connect to ground to get it to work correctly. If you look at the data sheets (which you have posted) you need to connect pins 7 and 8 to ground. If I remember correctly I just took a bent piece of a scrap resistor leg and solder it across both legs and one of the adjacent pins (whichever one connects to ground). The overflow pin is fine, that just sends out a signal when the record memory is full.

That is interesting about the chip you have, mine is definitely low-fi, granted I can really drive that home with the vibrato mod but even the straight recorded signal is very grainy and has the highs significantly clipped off.

[claytushaywood]

Some of the loophole videos and demos i've seen and heard definitely were not as lo fi as the junky.  Jakefuzz- yours sounds perfect as I'm finding all of your stuff does.  So pin 7 and 8 to ground is all you need to do to use the same chip?  any other value mods to other components in the build or anything?

[JakeFuzz]

Nope, I added a pretty involved mod that gives me vibrato, and a modified de-tune feature but the ISD25xxx will work fine without it. Sorry it took me so long to get back on this. Didn't see it till now. Thanks. I like to tweak things until they sound exactly how I like them, you could say I am a tweaker... 

[claytushaywood]

don't tell officer ham that!

[dromilious]

claytushaywood did it work your loophole with the isd2560?I have one spare and i think to make a try.So the only think you have to do is to jumper 7 and 8 pins to ground?

[shay1510]

JakeFuzz, two questions:
is there any chance u've got a pictue of the modded pcb?
does it matter which 25xx I use? (recording time differences?)
Thanks.

[JakeFuzz]

JakeFuzz, two questions:
is there any chance u've got a pictue of the modded pcb?
does it matter which 25xx I use? (recording time differences?)
Thanks.

You should be able to use all of the ISD25xxx line. They all have the same pin assignments they just all have different record times and sample rates. As for the PCB picture I didn't take one before it went in. I would take it out to take a picture of it but I also included my vibrato mod which makes pulling it apart a nightmare. But if you are just switching to the isd25xxx chip the PCB should look pretty much the same. I just soldered pins 7 and 8 together to the nearest ground connection (either pin 9 or 6 I don't remember which exactly). I used a spare resistor lead.   

[shay1510]

Thanks for the fast reply.
I guess now it's time to do some research on ISD25xx,
and find the IC with the best recording time/quality ratio.