Maestro FSH-1 trouble. Disappear noise oscillation

[chvan]

Hi everyone. I have trouble with s/h section. Sorry but I've built it on tonepad layout cause found madbeanpedals not so long ago. There're: lm13600, tc1044scpa, tl062, tl022, 2n3906, 2n5457 and bc548 for noise.

As you can see at related video sometimes disappear noise oscillation. Filter works fine. LFO opamp works fine too cause blinking led it shows. Also s/h section works well much of the time but sometimes and at low speed noise oscillation stops/freeze.

Trimpots not solve this problem. Is it important hfe of noise transistor? I've tried about 10pcs 2n3904 and no one not work. Their hfe about 300. 2n2222 with hfe 250 work but oscillation very often disappear. BC548 that I use now have hfe 550. It's work better but as you can see problem sometime appear. Do I need high gain transistors like 2n5088 or mpsa18? Now I'm not have another transistors and can't try. I've recently buy some 2n5088, mpsa18, 2n5089 from Tayda but still not get. It's strange cause most people use 2n3904 an 2n2222 and haven't this problem. Does anyone had such problem?

Thanks in advance.

http://www.youtube.com/watch?v=1bom4Wvxh7I