Rompstomp89
Well-known member
Hey guys,
Been on here a few times to discuss issues I've been having with some Vari-mu limiter builds.
I have built at handful of units with either the federal 864 or the altec 436 circuits.
This time I'm back to the 436 and am having an issue with distortion with a cranked input. Compression seems to help smooth out the distortion but Im probably only able to get around 10db of compression unit the unit starts to distort. Output is fine (checked with a scope) as well as the input on full volume i get a beautiful 1k sine wave after the .022 caps going to the 1Meg network that goes to ground. Ive been on the scope looking around and I found the distortion happening at the 220k network that goes to the wiper of the threshold pot. I did this test with the 6AL5 installed and not and got same distorted sine wave (see pics)
My build is not fully accurate per the schematic because I used parts that I had lying around.
My input transformer is an EDCOR 2.4-10K and my voltages are a little lower (about 20v lower on the 6bc8 and 40V lower at the OPT Center tap and 15V going into the Thresh Pot.
Would love some help/insight
Been on here a few times to discuss issues I've been having with some Vari-mu limiter builds.
I have built at handful of units with either the federal 864 or the altec 436 circuits.
This time I'm back to the 436 and am having an issue with distortion with a cranked input. Compression seems to help smooth out the distortion but Im probably only able to get around 10db of compression unit the unit starts to distort. Output is fine (checked with a scope) as well as the input on full volume i get a beautiful 1k sine wave after the .022 caps going to the 1Meg network that goes to ground. Ive been on the scope looking around and I found the distortion happening at the 220k network that goes to the wiper of the threshold pot. I did this test with the 6AL5 installed and not and got same distorted sine wave (see pics)
My build is not fully accurate per the schematic because I used parts that I had lying around.
My input transformer is an EDCOR 2.4-10K and my voltages are a little lower (about 20v lower on the 6bc8 and 40V lower at the OPT Center tap and 15V going into the Thresh Pot.
Would love some help/insight
