[Build Thread] Jasper, an EDP Wasp Clone

[bigsecret]

I'm wondering if anyone has any ideas as to why I am getting the same note from different keys being played. It's most noticeable with the three keys to the right of the A440, they are all making the exact same tone. The rest of the keyboard seems ok apart from these, I can't think what might be causing this issue. Any suggestions welcome!

I had a similar but more extensive issue with blocks of keys triggering the same note. In the end it was a short in the keyboard decoding section. Take a look at the schematics for the keyboard keyboard code multiplexer and check for a short between the three pins associated with the notes you are having problems with. You probably need to be looking at one of these three IC39, IC43, IC47

[Bodo1967]

Mine at first played only one octave, but twice - when I played the 'keys' one after another and reached middle C it would start the lower octave again instead of going to the upper one.

Turned out it was a little solder blob on the ribbon cable underneath the pcb.

So +1 for a short somewhere.

HTH.

[Pierre-Yves]

Hi again,

1. I still haven't solved the issue below (in hold mode 2, the filter enveloppe stops retriggering after a few secs).

To everyone: any ideal?

2. The range of the bend knob is only one note. Is it possible to extend it to one octave ?

Many thanks in advance,
Pierre-Yves

Hi everyone!

Just finished building my Jasper (two years after buying it...). Works great, I am able to get some real dirty sounds out of it (I'm into dirty sounds)!

I have just one problem, that I could not figure out : in hold mode 2 (S9, the one on the original Wasp I think), notes are holding alright and the envelope is retriggered everytime I hit a note (which is what I want), but only for about 10 seconds. After a few seconds, the envelope stops retriggering (notes are still held) when I touch the keyboard.

Could anyone give me some guidance on this ?

Thank you very much in advance,

Pierre-Yves

[gfosdike]

Hello,

I have just finished building a Jasper, and seem to have a bit of an issue. The following notes play without issue: E0, G0#, C1, E1, G1# and C2. The others all just pulse up and down, and C0 sounds like something from an old arcade game!

For the ones that work I can see they share the same pins on IC39,43 and 47, so there seems to be a pattern to whats going on. Just don't know where to go from here!

Any help would be greatly appreciated.

Regards

Gary

[gfosdike]

I have now found that if I keep my finger on he link port housing, the keyboard works fine. The same thing happens if you hold a metal probe onto pin G on link 2. So I'm guessing it's a grounding issue, just need to find where!

[gfosdike]

Help please,

Everything works as it should, except I have some sort of ground issue (perhaps?!).

When using the keyboard the pitch becomes unstable, especially for the lower frequency keys (it randomly jumps all over the place). However, when I put my finger on the top right ground point (or any other ground point), the problem goes away and it works fine.

Other information: it seems to operate fine when using hold (i.e. not using the keyboard). Also it behave a lot better (although maybe not quite perfect) when operating from batteries.

Please could someone with more electronics knowledge point me in the right direction of what might be going on?

Hello, did you ever get this sorted? It sounds like the same issue I'm having now!

[makhho]

.

[RadekTymecki]

Do you guys have that constant tone in the background? Jasper works fine btw...

Ps. I have 2 of them and the tone is slighly louder in the second one

[Maffez]

Hey! Just finished mine a couple of days ago after the kit sitting on the shelf for too long - big thanks to Jason for this and wow, what a great synth!

Couldn't help but also test some poetential for modifications and was mainly curious about VCO sync (as some of you have discussed earlier here). Not sure how legit and sane this is, but I got some passable results by feeding saw of VCO 1 via a diode and 3k3 resistor on a switch to the PLL cap of IC14 (junction Pin7 and C31). Here's some recording:

https://soundcloud.com/uibkmedan/jasper-vco-sync-test-2

Demo is horrible in musical terms and sync stuff sets in after 20 seconds or so. VCO 2 has a dedicated pitch modulation by LFO, which has, in turn, some half-baked note-on reset (would like to have its pitch modulated by the filter env but haven't gotten really far with that yet).

Again, this might not be very proper in technical terms, yet with VCO2 on square I quite like the results.

[tommy.york]

Did anyone else build the Psycho laser-cut-MDF case, and have a good Mouser part number for the speaker that would go on the midi / speaker panel? (top left slot here in the photo)

edit: this post could've gone in the psycho case v1 thread, but nonetheless I'll be trying 243-SC4.7ND-8OHM

[HyprDrivr]

Hello

Fianlly finished the case a year after i finished the synth

Just showing it of

[relggiwffum]

Hi! Building a Jasper here and we've noticed a difference comparing it to the original Wasp.
The Pitch pot does not have the same travel as the original. Could this be related to R142? The original schematics do not have this resistor. If the pot is turned to the max a resistance of 470 ohm is obtained instead of 2.2k as in Osc1 in Jasper.

Thank you!

[RadekTymecki]

since paia fatman is also based on 555 maybe this can be applied in jasper?

http://scott.joviansynth.com/fatman/hardsync.html

+

[Altitude909]

So i built up my other jasper and wanted to try something now that 3080s are available again: make a 3080 adapter for the 13700 in the filter. The difference is actually quite dramatic, much less screechy but it seems like the resonance needs adjustment, with the 3080s it doesn't get up there. I noticed the pots are different so ill try a 100k like in the wasp