ba662 internal wiring diagram

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guest
 
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ba662 internal wiring diagram

Post by guest »

im pretty satisfied with how the ba662 replica is working in the minix0x, so i posted up the wiring diagram in case anyone else wants to make one. its up with the rest of my x0x stuff:

http://wiki.openmusiclabs.com/wiki/x0xb0x

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altitude
 
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Re: ba662 internal wiring diagram

Post by altitude »

so wait, the VCA was done based your recollection of a data sheet? wow.

So if one were attempt make a SMD drop in clone (ala the Juno filters chips) are there matched transistors out there in a SOT package or IC based pairs (or triplets) better suited? My TM3030s have THAT300 parts which are 3 pairs IIRC..

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Re: ba662 internal wiring diagram

Post by guest »

there are a lot of matched pairs out there in SMT these days. i am using the pmp4201/5201 for the minix0x. they have amazing matching, and good beta. i picked them because they most closely matched the transistors in the 2sc1583. they are ok replacements for the 2sa733, and not the greatest for the 2sc536, but a lot of times the beta doesnt matter anyways. the THAT chips look really good on paper, but i havent used them. they come in quad pacakages.

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altitude
 
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Re: ba662 internal wiring diagram

Post by altitude »

would you mind posting the SCH file? I think I may want to give this a go and having that to build off of would help

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Re: ba662 internal wiring diagram

Post by guest »

i put up the .sch file and the corresponding .lbr for the pmp4201/5201 parts. im pretty sure it can be layed out as a single sided board as well, and quite small, so an actual 9-pin SIP might be possible.

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altitude
 
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Re: ba662 internal wiring diagram

Post by altitude »

perfect, thanks

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aminoacid
 
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Re: ba662 internal wiring diagram

Post by aminoacid »

This is really cool.

Id like to try one out some time.

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paradigm x
 
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Re: ba662 internal wiring diagram

Post by paradigm x »

Wow, cool.

I grabbed a knackered old SH09 recently and have been cleaning, fixing etc.

I was wondering why no-one had cloned until i saw its built out of obsolete parts, inc the ba662, in the filter interestingly. If someone could make drop in replacements that would be amazing.

Cheers

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Re: ba662 internal wiring diagram

Post by guest »

i am considering making drop in replacements, but its going to be a while before that happens. there is a cue of other things i need to get done first.

there are 2 options for making a replacement, using quads or duals. you would need 4 quads (which are about 5$ a piece) or 8 duals (which are 0.20$ a piece). the quads would be better, but i dont think the difference is worth the cost.

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altitude
 
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Re: ba662 internal wiring diagram

Post by altitude »

i think ill take a swing at it also

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paradigm x
 
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Re: ba662 internal wiring diagram

Post by paradigm x »

Cool

Well it all works fine at the moment, touch wood, but would be good to have a modern, che-ap (spam?) replacement in the future. Its a lovely synth.

Just need someone to clone the ua726 then...

Good luck, keep us posted. ;)

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e:pp:ik
 
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Re: ba662 internal wiring diagram

Post by e:pp:ik »

Excellent work on the BA guest.


+1 on that ua726! That has already become a necessity as far as I know.

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Re: ba662 internal wiring diagram

Post by guest »

a number of people have mentioned the ua726 to me. and im not sure if its something that can be done well enough, or at a reasonable cost. there are 3 approaches: 1. a direct copy on a pcb, put in a little can full of thermal paste. 2. a works-alike made out of a matched quad. 3. a works-alike made out of a matched pair and a bonded thermal sensor.

the first option will be pleasing to the purists, but it will work the worst, as the matched pair is not in direct thermal contact with the transistors doing the thermal sensing. it would have a moderate chance of fitting into the original package size, and would be moderately che4p to make.

the second option would work the best, but probably wouldnt fit into the same footprint, wouldnt make the purists happy, and would be rather expensive. if you were doing a new synth design, and needed a VCO that had no temperature drift, this would be the thing to use.

the third option would work pretty well, but not as good as the second option. it would have a moderate chance of fitting into the same footprint, and would be moderately che4p to make. it would also be the least loved by the purists.

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Re: ba662 internal wiring diagram

Post by guest »

so, we have these in stock now if you want to try one out:
http://www.openmusiclabs.com/projects/ba662-clone/

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altitude
 
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Re: ba662 internal wiring diagram

Post by altitude »

sweet ordered. You know what would work well for the legs would be the legs off those arduino headers, they are fairly narrow and thin

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