Wednesday, 12 February 2020

Jasper build notes - Part 2

This is part 2 of my Jasper build.
Part 1 is here.
https://djjondent.blogspot.com/2019/11/jasper-wasp-build-pics.html
The Jasper a a very very close version of the EDP wasp synth.
I have a couple of vintage ones so I'll try to calibrate this one as close as I can to the originals.
The originals are so fragile (and too expensive) to take outside the studio. Thus I'm building one Jasper for myself to gig with, and one for a friend.

This is where I left off in Nov 2019:


I had a lot of trouble finding the correct pots.

esp the double gang 1M.
The Mouser and Ebay  ones i bought were all the wrong size.

Small Bear is the place to get them.

 The pots need to mirror their PCB outline, or they wont slot into the faceplate correctly
 You will probably need to bend leads.

Avoid shorts at all costs,  .... use heatshrink



The BOM uses 17mm spacers. If the legs of the pots aren't long enough extend them with spare wire.
Be careful if you are bending them as they easily break.


tHIS is the reverse log pot. It's labeled C1M.
Almost there
Lining up the pots with the faceplate is tricky




iT'S time for the 9mm mix pots and the hold switch.
+ Potentiometers - Basic info for DIY

The Mix pots consist of Oscillator 1 & 2 volume controls and the external audio input.

Osc 1 & 2 use 50K log
Solder 3 wires to the pot


The ext audio input gain is a 100K log pot.
 "only solder 2 wires to the pot – this is used as a variable resistor in the gain
circuit of the input amplifier.............. as there is a 3 pin
header on the PCB – the third conductor is for a shield or gnd wire"

The Hold switch is a sub-miniature On-Off SPST or a DPDT on off on

"you have a choice when wiring up the Hold switch. There are two hold variants on the PCB:
•S8 Hold1: This holds the envelope open, and allows use of the Envelope repeat function.
•S9 Hold2: This was the hold feature on the v1 Jasper PCBs. It prevents the envelope from decaying. 


It's quite nice in that you can switch it on without playing the keyboard, and the hold only comes on when you hit a note. However it prevents the VCA repeat function from working.
If you're using a single SPST on-off switch, then you probably only want to wire it to connect to the S8 Hold1 header.
If you want to use both hold variants use a sub-miniature DPDT on-off-on toggle switch"


I'm using a DPDT


The Ext Trig Mod header connects to a switched jack socket.

The tip connection is marked as T, the switched is S and the ground/sleeve connection is G.




Decided to solder the pots direct to the PCB

Almost there..... powers up

to be continued........................

Links:
+ Jaspersynth
+ BOM
+ Build notes
+ DSL man.de
+ Knobs
+ Elby Knobs 
+ Potentiometers - Basic info for DIY
+ Muffs 
+ Muffs - 1 
+ Muffs - Build thread 
+ Buying Jasper
Mouser cart
 

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