Payback v1.1 Layout!

[Valoosj]

First thing tomorrow. It's midnight here and I have class from 11 to 14.

[Valoosj]

Ok, here is a vid of my looper.

http://www.youtube.com/watch?v=vmFHrQVml0E

I have to finetune the tone section and redo the wires so it will fit in the box. The record switch has to be replaced by a stompswitch.
This enclosure will not be used in the final product though.

[Valoosj]

One more question to Tonegod: is it normal that when the record volume is set past 11 o' clock that the recording stops (while listening to playback) the moment you strike a chord?

I cannot set my record volume past 11 o' clock while recording if I want to do chord riffs. I get a decent result with the record knob turned down and the volume knob past 12 o' clock. Just wondering if this is normal. Single notes don't have this effect on the recorded stuff.

As for the tone: it's better with a 100nF, but still decreases the volume a bit. Probably normal as high pitch notes are always a bit louder than lower pitch notes.

[darwin_deathcat]

FYI,  to all that are interested in making ISD chip based sampler/loopers, I have designed and tested a new circuit using the ISD1700 series chips. This may be of interest to you because it is next to impossible to find both the ISD1500's or the ISD1600's that are specified in the ToneGod's excellent designs. In fact I borrowed slightly from his designs: specifically I use a circuit snipet from Payback 1.0 to make the thing actually loop (without an eighth of a second pause in between!), and I use the idea of using a simple a passive mixer circuit to mix the looped output into the thru signal (from the payback 1.1, although I implement it slighltly differently than he does). However, I went with transistor-based buffers, and am using purely mechanical switching. I did this because a) I didn't have any opamps, and the transistor circuits actually take up less board space anyway, b) I didn't have any logic gate IC's, but I did have some nice metal-plunger momentary SPST and DPDT switches. I tested the switching to see if I was going to get any bad effects from switch bounce, and found that a basic R/C debouncing network worked very well with the ISD1700 (not sure about other ISD chips though). Also, one cool feature of the ISD1700's is the inclusion of a "reset" switch option that when pushed while the thing is looping causes it to go back to the begining of the loop. This not only will help you "sinc" up the loop to something else, but also lets you do a very cool "stutter" effect where you can make the first bit of the loop repeat, kind of like a DJ scratching a record! The ISD1700's also alow the recording of multiple tracks, so that if you do not erase the first track, whatever you record just gets tacked onto the end of the loop. Pressing an "erase" switch quickly ereases the last recorded track, or holding it down for about a second erases everything. My version has a momentary SPST "erase" switch, a latching "loop/play" SPDT switch, a momentary SPST "stutter switch, a momentary SPDT "record" switch (must be SPDT and wired so that you can momentarily stop playback while recording), and a latching SPST bypass switch (my circuit is designed so that you can have "almost" true bypass with just an SPST).
  So, I have the thing on my breadboard, and I am at a point where I am basically pleased with the performance. My next step will be to draw up the circuit as I have it now, and post it here (as a new topic) for suggestions before I build it. By the way, I found a GREAT enclosure for it the other day at the goodwill. It's a long, hinged aluminum case that was originally intended to store expensive steak knives! It provides a nice long strip for me to mount up all the switches with enough space that I won't have to worry about stepping on the wrong one!

[kierc]

Sounds very nice Darwin_Deathcat! 

[Valoosj]

FYI,  to all that are interested in making ISD chip based sampler/loopers,...

This sounds very nice, but too many switches if you ask me.

[darwin_deathcat]

Yes, I agree that there are quite a few switches to my design! But the beauty is that you only need three to make it work (record, erase, play/loop), and the other two (stutter, bypass) simply add some more functionality. In fact, the only thing that the "bypass" switch does is physically cut the output from the ISD to the passive mixing section, allowing the loop to continue playing while bypassed (good if you want to cut the loop playback for a bar, but then want it to continue from a bar later, or something like that). If you don't want/need that function, then you can simply omit the switch, and the unit will be (essentially) bypassed only when "play/loop" is off. The "stutter" switch can also be omitted, and the only loss is of the "stutter" function...
  BTW, i forgot to add that I also have a "wetness" pot to adjust the loop playback in the output mix, and am toying with a "rec level" pot to adjust the input signal level to the ISD (perhaps, but I'm not totally convinced on the necessity of such a pot since I haven't noticed any input clipping at the levels output from my preamp)...

anyway, I'll try to get a circuit drawing up within a couple of weeks. It's the end of the term here, and I'm currently busy with term papers, so this stuff will have to wait until I "clear up my schedule" a bit! 

[Musikermomo]

Did you "clear up your schedule"?  

[darwin_deathcat]

Sadly, I never did.. I got as far as getting the switches all wired up, but I got busy and never got around to finishing this thing... I've got to look at my drawings again because I can't remember the "trick" I figured out on to get this thing to actually loop! I should really finish this... It's pretty stupid that I never did!