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New schematic for Cracklebox with line output
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EpicFail



Joined: Jul 03, 2012
Posts: 10
Location: Bristol, UK

PostPosted: Sun Sep 02, 2012 7:34 am    Post subject: New schematic for Cracklebox with line output
Subject description: Cracklebox
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Hi All,

Following on from an old post (http://electro-music.com/forum/topic-10825.html&postorder=asc&highlight=cracklebox&start=25), I've been working on a schematic to incorporate the original design of the Cracklebox (originally called Kraakdoos, designed by Michel Waisvisz from STEIM, Amsterdam) with the line output circuit that bugbrand created and posted on this forum.

Don't think anyone has posted a schematic for this on the forum before, so thought it might be good to post and I'd also really like to see if people think it will work! I've not been doing elecronics very long, so I've probably made LOADS of mistakes!

My incorporation of both circuits is attached below (apologies for any incorrect terminology or symbols!).



Here is a link to the original Cracklebox circuit (see second schematic on page):

http://www.eam.se/kraakdoos/

Here is a link to bugbrand's line output mod (see final entry on page):

http://www.bugbrand.co.uk/bugbrand_old/pages/electronics.htm

The main things that I'm worried about with my incorporation are:

Is running both circuits off the same battery going to work?

I'm concerned about the point at which I depart from the original design and move into bugbrand's design. For instance, in my schematic, are R1 and C3 effectively doing the same job as R2 and R3? And if so, should R2 and C3 be omitted? This is probably a really basic question to anyone who knows about electronics, but I'm not sure about it. Also in that case, what happens about the connection from pin 2 to pin 6 of 709?

Anyway, enough rambling! Any thoughts on this greatfully received!

Cheers!


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umschmitt



Joined: Jun 29, 2011
Posts: 189
Location: brrlin
Audio files: 11

PostPosted: Mon Mar 07, 2016 6:24 am    Post subject: Reply with quote  Mark this post and the followings unread

Bringing up an old thread again… and this one wasn't actually answered. (i try to use still usable threads whenever possible. Call me eco-friendly).
Anyway. I started putting my fingers into this kraakdoos thing and i have a couple questions. The first one is: would this line output design work at all? I thought that the combination of the funny transistor array in the original design and the speaker load would play a role in the sound of the kraakdoos. Am i wrong?
About this NPN/PNP transistor apparel, what is it doing actually? Looks partly like a push-pull design but quite not really, like a darlington except it's not… I'm curious (and can't figure it out by myself).
Another question is about the isolation transformer. Is it potentially dangerous to ditch it? More than say… playing electric guitar without gloves?
Last question: would a simple BJT buffer do instead of the opamp? Maybe a JFET?
So many questions in so many directions!
All answers, informations, comments thankfully welcome!

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umschmitt



Joined: Jun 29, 2011
Posts: 189
Location: brrlin
Audio files: 11

PostPosted: Thu Apr 14, 2016 4:50 am    Post subject: Reply with quote  Mark this post and the followings unread

Ok after some breadboarding, it looks like:
* this line out only Cracklebox above (of course) kind of works but lacks all the nice typical sounds. Hard to get some, and they're limited.
* a 386 instead of the output transistors works. Not sure what the benefits could be though.
* a JFET buffer after the transistors works well for a line out (might sound obvious but this circuit seems to be so peculiar…). Didn't use any transformer there, should i?
* unfortunately a 10 ohm resistor in place of the speaker seems to bring less interesting sounds (that's a deception).Impedance inconsistencies of a speaker across the sprectum could play a role there, not sure. But i'll experiment further.
(As a side note, of course i checked the internetz prior to posting, but the information is very scarce on this line out Cracklebox topic, so i thought i'd ask here)

By the way here's a prototype layout (oh yeah it's a no-hole kind of thing!) i did to test the circuit. Sings like a bird!


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