GSSL High Pass Filter

Hi,

I know the subject has been opened a lot of times... but I'm not asking a question about the side chain! Well I have a GSSL with DBX 202C VCAs and the turbo board. I love it and it sounds much better than the THAT 2180 version, more "balls", sounds fuller and not as bright and agressive as the THAT. I also have a Neve Master Buss Processor which is a $4k piece of gear and I actually prefer the compression of my GSSL, much punchier (the Neve tends to smooth everything). I mastered a lot of albums with the GSSL, clients are happy.

Anyway, the GSSL is great but sometimes it's too much on some electro tracks, the sound becomes thin and narrow. Sometimes it's good cause it helps tighten everything in the low end when the kick is a little blurry, but sometimes it takes out the punch of the track. So I'm looking for a way to add a high pass filter, but I don't want to add the super side chain board (actually I would have to put 2 of them because of the turbo mod), no space in my rack and everything is securely fasten I don't want to remove everything (kinda lazy guy). So I was wondering, is there a simple way to add a high pass filter with a fixed frequency ? (let's say 100hz).

I know a guy explained one day on the forum he just put a capacitor with a switch somewhere on the circuit but I don't remember... I don't even need a switch, it's mostly for mastering so it will be always on. If you know a simple way to do that, that would be cool.

Thank you for your help!

joulss said:

I know the subject has been opened a lot of times... but I'm not asking a question about the side chain!

Click to expand...

Not much/any different to the other sidechainfilter subjects and sidechainfilter is your question.

So I was wondering, is there a simple way to add a high pass filter with a fixed frequency ? (let's say 100hz).

Click to expand...

Lots of ways to show where a frog has its curls. Easiest spot without cutting any pcb trace might be the substitution of the 22uF cap that connects to TL074-pin7 on both GSSL main board as well as turbo board. Next to this caps main purpose of blocking DC offset, this already is a 1st order HPF set at 1/(2*PI()*10000*22e-6)=0.72Hz. The '10000' is the value of the 20K||20K resistors connecting to virtual ground that follow this cap. For the -3dB cutoff point set at -for examples sake- 100Hz, just scale the cap value to 1/(2*PI()*10000*100)=1.59155e-7=159nF. If you keep the 22uF cap and connect this 159nF cap in series to this 22uF, you can make this HPF switchable by shorting out the 159nF cap. Some caps in parallel might get you closer to this not standard 159nF parts value, if cutoff -for whatever reason- has to be more or less exactly 100Hz. A standard 150nF cap will give a probably close enough response at 106Hz.

Thanks Harpo for your explanation, I will try to replace the caps and see how it sounds.

I just put a 100n capacitor (didn't have a 150n with me) instead of the 22u, so I should have something like 130hz, it works perfectly! The sound is great, now I can put some hip hop and electro tracks into my G-SSL, it still gives some glue to the mix without killing the bass frequencies.

Thanks again Harpo for your help!