Author Topic: How do I raise the level of WET part in BYOC 5konb compressor?  (Read 318 times)

swever

Damn I've got way to much stuff that I couldn't debug without help and have to put down. Been cleaning up my work table today and discovered this one http://effectslayouts.blogspot.ru/2015/05/walrus-audio-deep-six-compressor.html

Apparently it's actually a byoc 5knob compressor, not really a warlus deep six. Anyway it's a very nice sounding compressor.

The only issue is that the output level is way too low. With ratio (mix) set to 100% wet, it hardly achieves unity level even with both sustain and level controls set to max. It does some mild boost when I set the mix to 100% dry, though, which makes me think the problem lies somewhere in the "wet" signal path. Anything I may try to fix it?

PS there's a comment in the blog that R38 (second resistor in VrefA divider) must be 27k, not 56k. I changed it and I am not sure what kind of effect it has. I think it helped a bit, but I did not compare before and after. However, the output level is still below unity at 100% mix and sustain at zero, so I'd like to raise the wet output level a bit. What would be the best way to do that?

swever

Re: How do I raise the level of WET part in BYOC 5konb compressor?
« Reply #1 on: May 01, 2018, 03:35:12 PM »
I've just tried messing with Q4's collector and emitter resistors (R29, R30) and it does not seem to give the desired result.

I may be very wrong but I guess I need to increase the gain of the long tailed pair stage (Q5+Q6). Can't wrap my head around this stuff.

Kipper4

Re: How do I raise the level of WET part in BYOC 5konb compressor?
« Reply #2 on: May 01, 2018, 03:44:09 PM »
Schematic link will help.
As soon as I see the blog name I assume it's a vero layout.
I ain't no muff builder boi.
Smoke me a Kipper. I'll be back for breakfast.

swever

Re: How do I raise the level of WET part in BYOC 5konb compressor?
« Reply #3 on: May 01, 2018, 03:49:00 PM »
Schematic link will help.
As soon as I see the blog name I assume it's a vero layout.

There's a link to the blog in the original post. The layout and schematic are there. It's an home etched PCB.

Kipper4

Re: How do I raise the level of WET part in BYOC 5konb compressor?
« Reply #4 on: May 01, 2018, 04:10:02 PM »
The major difference between your blog. Byoc and the std Ross/dyna comp is the huge booster on the dry path q2.

Take a look at the Ross
https://www.electrosmash.com/mxr-dyna-comp-analysis

I guess you could try to adjust the q2. Maybe try a 10k Re.
Maybe make R11 bigger.

I guess the whole booster is something desirable. I haven't tried it.

Is your R13 wiper at 4v5 ?
I ain't no muff builder boi.
Smoke me a Kipper. I'll be back for breakfast.

swever

Re: How do I raise the level of WET part in BYOC 5konb compressor?
« Reply #5 on: May 01, 2018, 04:29:10 PM »
The major difference between your blog. Byoc and the std Ross/dyna comp is the huge booster on the dry path q2.

Take a look at the Ross
https://www.electrosmash.com/mxr-dyna-comp-analysis

I guess you could try to adjust the q2. Maybe try a 10k Re.
Maybe make R11 bigger.

I guess the whole booster is something desirable. I haven't tried it.

Is your R13 wiper at 4v5 ?

Yep, R13 wiper is at half supply.

The dry signal path's level is just a touch above than unity now. I think it could have been higher, but that's not the main concern now. The wet signal is way too low.

Are you referring to Q2 as per the schematic in the blog, or the original ross/dyna? If the former, I'd rather not touch it right now because it's the dry path (if I am not mistaken) and I'd rather keep it at where it is now. I need to significantly increase the WET level (before the mixer).

Kipper4

Re: How do I raise the level of WET part in BYOC 5konb compressor?
« Reply #6 on: May 01, 2018, 04:39:12 PM »
Yes I refer to your blog schematic with q2 and r13 ratio.

If you want more wet maybe lower R15. Blog.

I ain't no muff builder boi.
Smoke me a Kipper. I'll be back for breakfast.

swever

Re: How do I raise the level of WET part in BYOC 5konb compressor?
« Reply #7 on: May 01, 2018, 05:45:44 PM »
Yes I refer to your blog schematic with q2 and r13 ratio.

If you want more wet maybe lower R15. Blog.

I had to go as low as 220 Ohm for R15 to get the wet level in the desired range. I was about to say "that's it" when I tried tweaking the mix knob only to discover that the dry signal is now amost completely gone. Is it R12 I need to change to compensate now?

swever

Re: How do I raise the level of WET part in BYOC 5konb compressor?
« Reply #8 on: May 01, 2018, 06:02:48 PM »
Tried decreasing R12. What I get now is almost zero level at both extremes of the mix. It is, however, more or less okay at the midpoint.

I wonder if there is a way to increase the gain of the wet signal path without messing with the mixer.

GGBB

Re: How do I raise the level of WET part in BYOC 5konb compressor?
« Reply #9 on: May 01, 2018, 07:20:38 PM »
The only issue is that the output level is way too low. With ratio (mix) set to 100% wet, it hardly achieves unity level even with both sustain and level controls set to max. It does some mild boost when I set the mix to 100% dry, though, which makes me think the problem lies somewhere in the "wet" signal path. Anything I may try to fix it?

That suggests that you have a faulty build, not that there is something wrong with the design (unless everyone else who has built the same circuit reports the same problem - in which case there surely must be a standard remedy online somewhere already). So you should follow standard troubleshooting procedure here (probe, check voltages and values etc.) rather than look for a band-aid solution.

swever

Re: How do I raise the level of WET part in BYOC 5konb compressor?
« Reply #10 on: May 02, 2018, 05:28:03 AM »
That suggests that you have a faulty build, not that there is something wrong with the design (unless everyone else who has built the same circuit reports the same problem - in which case there surely must be a standard remedy online somewhere already). So you should follow standard troubleshooting procedure here (probe, check voltages and values etc.) rather than look for a band-aid solution.

I never really ruled out an error in my build or (less likely) in the layout. As for everyone else, I was never able to get any feedback from others on this particular circuit/layout.

My line of thought was that since the circuit sounds right it should be okay all in all. Due to some component tolerance or some other factor, the wet signal is just a touch lower than I'd love it to be, so I just wanted to figure out a way to push it up a bit. Which must be not too hard because there are plenly of gain stages in the ciruit. It's just that I lack the knowledge to figure out how exactly to do just that.

My voltages:
+9: 7.84

q1e 1.77
q1b 2.16
q1c 6.04

q2e 0.23
q2b 0.80
q2c 5.34

q3d 7.36
q3s 0.16
q3g 0.00

q4e 3.23
q4b 3.82
q4c 4.56

q5e 0.00
q5b 0.00
q5c 7.78

q6e 0.00
q6b 0.54
q6c 7.78

q7e 6.66 (keeps growing slowly)
q7b 7.20 (keeps growing slowly)
q7c 7.41 (keeps growing slowly)

ic1 3.59
ic2 3.59
ic3 0.00
ic4 1.18
ic5 0.00
ic6 3.63
ic7 3.63
ic8 3.71
ic9 7.64

rankot

Re: How do I raise the level of WET part in BYOC 5konb compressor?
« Reply #11 on: May 02, 2018, 07:47:30 AM »
Interesting. I've built Ross compressor long time ago and it is by far the loudest compressor I have (and I have a LOT). :) Maybe I shall do the opposite and make it a little bit quiter.
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duck_arse

Re: How do I raise the level of WET part in BYOC 5konb compressor?
« Reply #12 on: May 02, 2018, 10:41:23 AM »
I don't know if it is your cause/problem or not, but I'd say Q6, being isolated from DC, should not have 0V54 on its base. if Q4 emitter was connecting to R32, you might get some DC volts there.
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