using matched pair . 1/ there matched for you. 2/ because they are on same die the first thermal error is cancelled. which is perfect for vca.
3 / Erica synths sell the https://www.ericasynths.lv/shop/diy/diy-accessories/as394-matched-transistors/ for cheap.
time is money and matching transistors takes time.
the transistors ken chose for noise are good the other good one is a 2n5172 but pin out is different.
On 06 July 2018 at 12:51 "Ken Stone otherunicorn@... [cgs_synth]" <cgs_synth@yahoogroups.com> wrote:
You may have to try a lot of different transistors to get one that is noisy enough. I selected the 4250 because they were all noisy to the point of some of them being too noisy.
For transistors, the better the matching, the better they work - less bleed through. Try them and see if you are happy with the result.KenOn Fri, Jul 6, 2018 at 9:04 PM, Mike Burnham mikejburnham@... [cgs_synth] <cgs_synth@yahoogroups.com> wrote:
Hi there
For the Serge Noise circuit it specifies the noise transistor as 2n/PN4250 but these are stupidly expensive nowadays
Is it possible to use BC557? Are they noisy enough? BC557C probably best?
The VCA specifies a matched transistor package
Would matched 2N3904 be OK? Or do they have to be super matched?
Thanks
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