DIY Sidechain question...

[mrharrell]

I've got a BYOC Optical Comp that I really like. However, I wish it had a sidechain option so I could compress my mids/highs mores than my lows. The goal would be to beef up those mids/highs and leave the lows unaffected.

I got to thinking, what if I split my signal and sent one to the EQ pedal -> BYOC -> reverse Y cable -> DI

Would this be a decent poor mans sidechain option?

 

[J Posega]

A side chain isn't quite what you need. Sounds more like you want a dual-band compressor that can compress your top end and bottom end separately.

Like this one Parametric Multi-Band Compressor – Build Your Own Clone

 

[mrharrell]

I saw that dual on the BYOC site. I think general consensus here is that it has a set ratio of infinity:1, perfect for limiting separately, but I want to compress my top for the tone benefit not for limiting.

 

[SGT. BAKER]

I saw that dual on the BYOC site. I think general consensus here is that it has a set ratio of infinity:1, perfect for limiting separately, but I want to compress my top for the tone benefit not for limiting.

Maybe the EBS Multicomp was what you´re looking for. It can works in multiband too, so you can choose how much compressing your lows ands your highs separately. And the ratio it goes 5:1 maximun.

 

[boomertech]

I've got a BYOC Optical Comp that I really like. However, I wish it had a sidechain option so I could compress my mids/highs mores than my lows. The goal would be to beef up those mids/highs and leave the lows unaffected.

I got to thinking, what if I split my signal and sent one to the EQ pedal -> BYOC -> reverse Y cable -> DI

Would this be a decent poor mans sidechain option?

There are a couple of ways to remove some bass energy from the side-chain in this compressor. Do you want it adjustable, switchable or fixed valued permanently?

-Frank

 

[boomertech]

I saw that dual on the BYOC site. I think general consensus here is that it has a set ratio of infinity:1, perfect for limiting separately, but I want to compress my top for the tone benefit not for limiting.

This BYOC Optical compressor is designed by the same person that designed the BYOC dual band compressor. They are both heavy compressors with fixed infinity:1 ratios... limiters.

-Frank

 

[mrharrell]

There are a couple of ways to remove some bass energy from the side-chain in this compressor. Do you want it adjustable, switchable or fixed valued permanently?
-Frank

Having it adjustable would be my 1st choice. Switchable second

This BYOC Optical compressor is designed by the same person that designed the BYOC dual band compressor. They are both heavy compressors with fixed infinity:1 ratios... limiters.
-Frank

GAH! That thought never crossed my mind. So the sustain knob controls the ceiling, and the level knob the floor of the threshold?

 

[mrharrell]

@boomertech you now have me wondering if I should just play around with some capacitors and see if a fixed value works. Maybe if I used two capacitors on the input jack of the pedal, one that blocks lows wired in series with the cables going into the PCB, and the second capacitor that blocks the corresponding mid/upper freqs wired in series from the input to output jacks.

 

[boomertech]

If you look at the schematic you will see that the Q1 and Q2 opto drivers have HP RC filters, R9/C4 and R8/C5. The value of 220K for R8 and R9 with their 0.047uF capacitors, make a HP filter with a corner frequency of approx 15Hz. If you decrease the value of R8 and R9 to 22K the HP corner frequency changes to 150Hz. And a resistor value of 2K2 will change the HP corner frequency to 1500Hz.

So, use a linear taper dual-ganged 250K pot connected as an adjustable resistor with a 2K2 in series with it for R8 and R9. This will give you the range of side-chain filtering shown above.

BTW, there is an error on that schematic for the LED side of the opto. The way it is drawn will not work.

-Frank

 

[boomertech]

Either one of these connection diagrams will work.

Or this one:

-Frank

 

[boomertech]

...
GAH! That thought never crossed my mind. So the sustain knob controls the ceiling, and the level knob the floor of the threshold?

The threshold is set by the Vbe barrier (approx 0.7V) of Q1 and Q2. It is not an adjustable threshold. When the sust control is adjusted, you are changing the gain for IC1a. The higher the gain, the more the audio signal will be turning on Q1 and Q2 to reduce the gain. The level control is just an output level control.

-Frank