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Cfish
Joined: Feb 24, 2016 Posts: 477 Location: Indiana
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Posted: Mon Jan 16, 2017 7:26 am Post subject:
Minimoog VCF question |
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I am getting everything together to build the yusynth minimoog filter.
I usually use 2n3904 and 2n3906 to replace BC547 and BC557s.
I have many pairs matched and ready to go.
Not being fermillior with this build, I was wondering if the differences i between the 3904 and 547 would cause problems.
They are close inough in the datasheet for most things I do. But I don't want to regret making the switch. |
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LFLab
Joined: Dec 17, 2009 Posts: 497 Location: Rosmalen, Netherlands
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Posted: Mon Jan 16, 2017 8:50 am Post subject:
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Some grades of the 2N3904 are lower gain than the "C" range of the BC transistors, not sure how crucial this is. For the rest, interchangeable. Joe Beuckmann did a Moog Taurus clone, which also uses 2N3904's, you might look into his project for clues.
I did do a Minimoog VCA recently (in addition to to the combination of VCF and VCA I did last year, and which is great), but it is not working properly yet, the difference between the builds is (probably amongst other changes) that this time around I used "C" grade, where I used "A" earlier, and I used a different way of Vbe matching (earlier Ian Fritz, now Peak Atlas DCA75, latter is not good enough).
In my VCF build I also matched the caps, by the way. |
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Cfish
Joined: Feb 24, 2016 Posts: 477 Location: Indiana
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Posted: Mon Jan 16, 2017 12:01 pm Post subject:
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Thanks Lf lab.
Sounds like I may want to take a closer look at my matching procedure before I proceed.
I have built many modules on perf, however this will be my first kit build.
I would like the results to be good on the first try. |
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gdavis
Joined: Feb 27, 2013 Posts: 359 Location: San Diego
Audio files: 1
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Posted: Mon Jan 16, 2017 1:12 pm Post subject:
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I've built several of these filters for my poly synth with transistors and caps presumably from the same batch but otherwise no matching done at all and they all worked fine to my ears. _________________ My synth build blog: http://gndsynth.blogspot.com/ |
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gabbagabi
Joined: Nov 29, 2008 Posts: 651 Location: Berlin by n8
Audio files: 23
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ricochet
Joined: Oct 03, 2017 Posts: 4 Location: Münster, Germany
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Posted: Wed Dec 13, 2017 6:25 am Post subject:
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Thx for that GG
another question about
" Matching Capacitor"
C4...C7 (Minimoog VCF) should "..matched to 1%"
does that mean:
a) 1% near 47nF
or
b) all the 4 capacitors in a range of 1% , perhaps 48,01....48,9nF ?
Gerd |
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Wed Dec 13, 2017 3:16 pm Post subject:
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b) all the 4 capacitors in a range of 1% , perhaps 48,01....48,9nF ?
The value of 47nf is not critical but the matching of the different caps is important _________________ Yves |
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