8CH low cut filter or modification mixing console?

Maros

Maros

New member
Hi,

I have A&H GS3 mixing console it is good for my analog multitrack recording but I really missing low cut filter or selectable shelving / peak EQ on LF. There is only a sweepable peak EQ on LF (20Hz to 600Hz). The problem is when I cut some mud for example at 150Hz, I still heard rumbling at lower frequency, but I do not have a knob for it.

I like to cut lows on vocals, guitars and so on. So I am thinking about external low cut filter which I inserted into channel, or I will modify mixing console (not really happy with this). Something like this:

Harrison Consoles

But maybe less complicated. Is there any good solution? I was thinking about simple TRS jack male/female connector with high pass filter inside for desired frequency (80Hz?). If want it - I plug it into insert channel and all my efects will be after that. Something like this but with TRS jack: Line Level Crossovers

Or maybe I will make something by myself. I making tube gear into studios but I really do not want to built everything (its simple but really time consuming).



Thanks!
 
I have an A&H Zed428, and it has a hi-pass button just below the gain trim on each channel. Doesn't the GS3 have this?
 
If you don't mind a gentle 6dB/octave roll off you could easily build you own filter by simply adding a capacitor between the tip and the ring of a TRS plug and using it in the insert on the desk. The main issue is deciding on the value of the capacitor as you need to know the input impedance of the stage after the insert to calculate the correct value. The time constant of the circuit gives the -3dB point of the filter so, for a 100Hz filter we need a time constant of 0.01 seconds (10mS). If we assume the input impedance to be 10k ohms this gives a capacitance of 1uF.

However, having had a quick look at the schematic it appears that, while 10k ohms is a sensible input impedance for the insert with the eq bypassed, with the eq in circuit the input impedance is probably higher so you will want to use a lower value of capacitor - something like 0.33uF or even 0.22uF might be better. It may be better to have a selection of TRS jacks with different capacitors in them for different applications.
 
bouldersoundguy said:
Shure A15HP

Shure A15HP - Hi-Pass Filter A15HP B&H Photo Video
Click to expand...

XLR :(

gecko zzed said:
I have an A&H Zed428, and it has a hi-pass button just below the gain trim on each channel. Doesn't the GS3 have this?
Click to expand...

Unfortunetaly, not :(


jamesperrett said:
If you don't mind a gentle 6dB/octave roll off you could easily build you own filter by simply adding a capacitor between the tip and the ring of a TRS plug and using it in the insert on the desk. The main issue is deciding on the value of the capacitor as you need to know the input impedance of the stage after the insert to calculate the correct value. The time constant of the circuit gives the -3dB point of the filter so, for a 100Hz filter we need a time constant of 0.01 seconds (10mS). If we assume the input impedance to be 10k ohms this gives a capacitance of 1uF.

However, having had a quick look at the schematic it appears that, while 10k ohms is a sensible input impedance for the insert with the eq bypassed, with the eq in circuit the input impedance is probably higher so you will want to use a lower value of capacitor - something like 0.33uF or even 0.22uF might be better. It may be better to have a selection of TRS jacks with different capacitors in them for different applications.
Click to expand...

Yes, something like that. But it must be swichable if I do not want to use it. I could make -40dB/decade roll off with 2 RC network in series with single transistor emitor follower to ensure independance from next input impedance. But this require power supply :( Phantom voltage is missing on insert point - of course.

This is passive version I create. But bypass switch is complicated because lack of impedance buffer on tape in / line in input - there is R17 10k resistor. If buffer was included there was be only switch across capacitors.

But again too much work for old mix console :( Maybe really cheapest solution will be 1U rack with 8x HP filter.

HP filter.jpg
 
Last edited:
Maros said:
XLR :(
Click to expand...

Console HPFs are on the inputs, not on the inserts. If you're going to high pass it, that's the place to do it. They're pretty much upstream of everything including the pre-fader sends. Eq varies. It's often downstream of inserts and pre-fader sends, and inserts are generally downstream of pre-fader sends.
 
bouldersoundguy said:
Console HPFs are on the inputs, not on the inserts. If you're going to high pass it, that's the place to do it. They're pretty much upstream of everything including the pre-fader sends. Eq varies. It's often downstream of inserts and pre-fader sends, and inserts are generally downstream of pre-fader sends.
Click to expand...

If you look into schematic there is no better place for HPF. Because there is REV button for select input from mic/line/tape and thats the point right where insert jack is.
 
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