Author Topic: zvex lofi loop junky - hows that work?  (Read 21009 times)

ethrbunny

zvex lofi loop junky - hows that work?
« Reply #40 on: November 17, 2004, 10:30:19 AM »
32% scaling of the jpg was too small. Is there anyway to figure out what the proper scaling would be before I order a new board?
--- Dharma Desired
"Life on the steep part of the learning curve"

gurutzeta

zvex lofi loop junky - hows that work?
« Reply #41 on: November 17, 2004, 12:46:59 PM »
Quote from: ethrbunny
32% scaling of the jpg was too small. Is there anyway to figure out what the proper scaling would be before I order a new board?

Print it and check that the distance between holes of pins of the opamps is correct, for example. That is how I did it at least.

Torchy

zvex lofi loop junky - hows that work?
« Reply #42 on: November 17, 2004, 12:48:47 PM »
crp

gurutzeta

zvex lofi loop junky - hows that work?
« Reply #43 on: November 17, 2004, 01:25:40 PM »
Quote from: Torchy
Quote from: gurutzeta
It is a JFET. I use BS170.


Thats a mosfet ...

Thanks for the correction, I was testing to see if you all were paying attentiont  :wink: .

ethrbunny

zvex lofi loop junky - hows that work?
« Reply #44 on: November 18, 2004, 11:43:06 AM »
Im trying to decide whether or not to 'frankenstein' the board with jumpers to a board with just the ICs. .. hmm.. what is my time worth.. hmmm...
--- Dharma Desired
"Life on the steep part of the learning curve"

ethrbunny

zvex lofi loop junky - hows that work?
« Reply #45 on: December 01, 2004, 07:49:36 PM »
ok. got a new board. sockets fit now. am slogging ahead!
--- Dharma Desired
"Life on the steep part of the learning curve"

Michael Allen

zvex lofi loop junky - hows that work?
« Reply #46 on: December 01, 2004, 08:15:58 PM »
this is gonna be righteous

ethrbunny

zvex lofi loop junky - hows that work?
« Reply #47 on: December 01, 2004, 08:38:46 PM »
Quote from: Michael Allen
this is gonna be righteous


.. lets hope ..

Im still questing about for enclosures for this and for a 'fender blender'.  Suggestions?

Hmm... I wonder if my daughter would miss her elmo doll..

"daddy - why are you stepping on elmo? and why are his eyes blinking?"
--- Dharma Desired
"Life on the steep part of the learning curve"

ethrbunny

zvex lofi loop junky - hows that work?
« Reply #48 on: December 01, 2004, 11:32:22 PM »
Gurutzeta - 2 questions

1) what is d4? another 1N4148?
2) R8 - 3.2M ? Really?

Hopefully I can post a pic of the built board soon.
--- Dharma Desired
"Life on the steep part of the learning curve"

Michael Allen

zvex lofi loop junky - hows that work?
« Reply #49 on: December 02, 2004, 12:52:18 AM »
how bout a picture of the board itself?

zachary vex

zvex lofi loop junky - hows that work?
« Reply #50 on: December 02, 2004, 01:21:58 AM »
Quote from: gurutzeta
Quote from: ethrbunny
How would you go about adding the vibrato to the circuit? Just having the effects loop is v nice. Maybe just a 'blend' control to set how much the effects loop touches the sound.


I would need to check the datasheets again, but I guess it is a matter of disconnecting pin 26 of the ISD chip (XCLK) from ground and putting there some weird oscillator that changes frequency... sort of a pwm of a sinusoidal LFO, maybe... I am not sure if I left that very clear.... basically you need to have a clock with an oscillating frequency... Something like the oscillator used for flangers, a VCO which is fed an LFO, I guess....


it's easier to just vary the supply voltage to the chip.  8^)  but don't go too high!  it'll make the chip freeze up.  the trick is to set up an oscillator that varies the chip's power supply in equal amounts up and down from the record voltage (and turn off the vibrato during record, of course) so that the average pitch is about equal to the original guitar pitch and the overall time for playback is identical to the time it takes with the vibrato off... if your oscillation biases the average dc voltage lower than the non-vibrato voltage, the loop will play longer with the vibrato on, the sample will play back generally flat, and it will screw up the timing during performance.

Dragonfly

zvex lofi loop junky - hows that work?
« Reply #51 on: December 02, 2004, 10:44:01 AM »
Quote from: RDV
Looky here!
http://www.twinhunter.com/catalog_detail.php?id=243

RDV



hmmmmmm......ready made looper.....

gurutzeta

zvex lofi loop junky - hows that work?
« Reply #52 on: December 02, 2004, 03:06:11 PM »
Quote from: ethrbunny
Gurutzeta - 2 questions

1) what is d4? another 1N4148?
2) R8 - 3.2M ? Really?

Hopefully I can post a pic of the built board soon.


1) Yes, all diodes are 1N4148.
2) Yes, I used 3.2 M. It is making an inverter amplifier together with OA2 and P2. The relationship is ANAin = - ( P2/R8 ) * InFx
You might replace it with a different value if you also change P2 (as long as you keep the same value for P2/R8 )

gurutzeta

zvex lofi loop junky - hows that work?
« Reply #53 on: December 02, 2004, 03:08:11 PM »
Quote from: zachary vex

it's easier to just vary the supply voltage to the chip.  8^)  but don't go too high!  it'll make the chip freeze up.  the trick is to set up an oscillator that varies the chip's power supply in equal amounts up and down from the record voltage (and turn off the vibrato during record, of course) so that the average pitch is about equal to the original guitar pitch and the overall time for playback is identical to the time it takes with the vibrato off... if your oscillation biases the average dc voltage lower than the non-vibrato voltage, the loop will play longer with the vibrato on, the sample will play back generally flat, and it will screw up the timing during performance.


Shit!!! did not think about that!!! Thanks ZVEX...

mathflan

can I put a "IC, ISD25120P " with 120s into that c
« Reply #54 on: December 15, 2004, 05:43:12 PM »
hi! guys
so thanks gurutzeta!

it's HUGE

I want to mad this effetc but can I put ISD25120P  with 120s into that circuit???. so i can I have 120s , maybe it's not useful to have a lot seconde loop??

Where I can thes IC??
http://www.jameco.com??? is good??thanks
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http://sounddiy.free.fr
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gurutzeta

Re: can I put a "IC, ISD25120P " with 120s into th
« Reply #55 on: December 15, 2004, 06:02:00 PM »
Quote from: mathflan
I want to mad this effetc but can I put ISD25120P  with 120s into that circuit???. so i can I have 120s , maybe it's not useful to have a lot seconde loop??


You could do it, but it would reduce the quality of the looped sound dramatically. Up to you.

Quote from: mathflan
Where I can thes IC??
http://www.jameco.com??? is good??thanks


I got them from http://rswww.com

ethrbunny

zvex lofi loop junky - hows that work?
« Reply #56 on: December 15, 2004, 07:05:21 PM »
Why would the longer-storing winbond chips have a lower quality of playback?
--- Dharma Desired
"Life on the steep part of the learning curve"

zachary vex

zvex lofi loop junky - hows that work?
« Reply #57 on: December 15, 2004, 11:39:41 PM »
you can look at the frequency response of each type of winbond chip at their website.  they vary from somewhere in the 2k range to above 3k... i have listened to the 3k versions and i've found that not only do they sound somewhat more noisy because of the filter response, but they have a very annoying tone to them with that hard knee near 3k.  it's actually a smoother sound to have them rolled off in the mid 2k region because it's easier on the ear.  people over 30 especially have a sensitivity to sounds in the 3k "spike" area of the spectrum.  sometimes, more is NOT better.  8^)

i don't think that the longer winbond chips have a response that's much lower than the short ones.  the biggest problem with winbond is that they changed their control circuitry so many times that it makes your head spin when you try to come up with circuits to make them into effective loopers.  the one i use, the 1420, can be replaced with another in the 1400 series that is slightly shorter but has higher frequency response, and i've never liked a thing about it.

ethrbunny

zvex lofi loop junky - hows that work?
« Reply #58 on: December 16, 2004, 12:36:08 AM »
Eeeek.  :shock: Well, I ordered a 2560 for my Gurutzeta box.. I hope it will work ok.
--- Dharma Desired
"Life on the steep part of the learning curve"

gurutzeta

zvex lofi loop junky - hows that work?
« Reply #59 on: December 16, 2004, 02:52:20 AM »
Quote from: ethrbunny
Eeeek.  :shock: Well, I ordered a 2560 for my Gurutzeta box.. I hope it will work ok.


60 should be OK is from there onwards that starts getting bad. Basically the 120 is the same chip as the 60 but with a sample frequency of half of the one in the 60.

Bellow 60 the chips are the same as the 60 (sample frequency wise) but with less capacity, less "analog memory"