Testing yhe x0x

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krinkel
 
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Joined: Fri Mar 07, 2014 6:00 am

Testing yhe x0x

Post by krinkel »

I bought my x0x at x0xsh0p.de but it doesn't sound like it should be. I do have to do all the tests and tuning but before I can do that I have one question. Is it enough to remove the cpu to do all the tests or are there other ic's that should be removed before I start testing?

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antto
 
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Joined: Thu Apr 15, 2010 3:21 pm

Re: Testing yhe x0x

Post by antto »

what tests?

why would you have to remove the cpu

krinkel
 
Posts: 22
Joined: Fri Mar 07, 2014 6:00 am

Re: Testing yhe x0x

Post by krinkel »

In the ladyada build manual they mention some tests (vco, vcf, envelope and vca). In the envelope section they say you have to remove the microcontroller before you do the tests but I want to be absolutly sure that's all I have to remove.

http://www.ladyada.net/make/x0xb0x/fab/vco.html
http://www.ladyada.net/make/x0xb0x/fab/vcf/index.html
http://www.ladyada.net/make/x0xb0x/fab/env/index.html
http://www.ladyada.net/make/x0xb0x/fab/vca/index.html

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antto
 
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Re: Testing yhe x0x

Post by antto »

all these tests are during the build process, because the whole thing is not put together yet (specifically, the sequencer section is built last)

on a fully built x0xb0x - you don't have to follow the tests exactly (unless something is malfunctioning)

if the x0x plays notes at the correct pitches, the filter "filters", the knobs change the tone as expected - then it works (it should sound and behave like a 303)
an easy way to test that is to program a famous pattern and listen if everything is correct..

what you could do is calibrate the synth a bit
first, calibrate the 5.333V line (using TM6 in the IO board)
then calibrate the VCO ***
then calibrate the cutoff freq to taste (TM3)

other than that, if something doesn't sound right - identify it (or record a sample) and it can probably be modded (example: not enough resonance -> resoboost mod)

*** you can use my special tuner (windows vst plugin) to tune the VCO, or at least read the information there, because there are two possible ways to tune the VCO, and one of them is plain wrong/hard/slow/iterative (and most people go that way)
the build manual on the VCO section proposes the easier way, however it still applies to a brainless x0x (you inject voltage to the vco and probe with scopes.. blah)
i propose the same (easy) method, but using the sequencer to provide the pitch (CV) to the VCO and using a computer to monitor the frequency..
http://antonsavov.net/cms/projects/as_x0x_tune.html

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