ytsestef
Well-known member
So, I finished my Nite EQ / EQ3D / Airband EQ / whatever it is called the other day, I wanted to share with you
It worked flawlessly on first powerup, and that's only because it is a very well-designed project. Props to kevin and peter!
I decided to build it on a 2U chassis and have wires to the front panel pots, because I am not confident enough that I can drill with such precision to mount the PCB directly to the panel. This also helped me keep both channels in a safe distance from the toroid transformer, so it's never bad to minimise the hum. The pots are OMEG 470k rev.logs with center detent (thanks Colin), although I was a bit careless and bought them all with center detent (including the boost-only airband). Oh well... I also screwed up in the front panel labeling a bit, the 2.5k band is shelving, I drew a bell curve... grrrr! Way to lazy to repaint it! The case is way too big, but I found it quite cheap so I thought "what the hell". I'm not satisfied with the XLR connectors in the back, next time I'll definitely go for some neutrik or switchcraft ones... BTW, the PSU is the SSL9k one. Omitted the +48V line and was done with it
The omegs in the center detent measured quite higher than 56k2, which has to be the sum of the series resistor and the pot for a gain of 1. Most of them were in the ~60k range, so, instead of calibrating each one I just replaced all the series resistors with 3.3k (I was afraid if I went lower the opamps would self-oscillate when the pot was in the max.gain position) and was done with it. Still I can hear no difference in bypass and engaged mode when all pots are in the center, so maybe after all the gain controls aren't THAT sensitive.
And now I need a little help. ;D I'm not sure how to ground this thing. As you can see this case has an bare aluminium plane on the bottom, on which I drilled a hole and put a screw as a grounding point. However, this is only grounding the plane, and not the case. I have already installed another screw on the back of the case (can be seen in the photo, not too good though, it is next to the XLR connectors), but then the plane will be floating. If I connect the plane to chassis (from one screw to the other) will I get a ground loop? If I leave it like this it isn't safe, is it?
It worked flawlessly on first powerup, and that's only because it is a very well-designed project. Props to kevin and peter!
I decided to build it on a 2U chassis and have wires to the front panel pots, because I am not confident enough that I can drill with such precision to mount the PCB directly to the panel. This also helped me keep both channels in a safe distance from the toroid transformer, so it's never bad to minimise the hum. The pots are OMEG 470k rev.logs with center detent (thanks Colin), although I was a bit careless and bought them all with center detent (including the boost-only airband). Oh well... I also screwed up in the front panel labeling a bit, the 2.5k band is shelving, I drew a bell curve... grrrr! Way to lazy to repaint it! The case is way too big, but I found it quite cheap so I thought "what the hell". I'm not satisfied with the XLR connectors in the back, next time I'll definitely go for some neutrik or switchcraft ones... BTW, the PSU is the SSL9k one. Omitted the +48V line and was done with it
The omegs in the center detent measured quite higher than 56k2, which has to be the sum of the series resistor and the pot for a gain of 1. Most of them were in the ~60k range, so, instead of calibrating each one I just replaced all the series resistors with 3.3k (I was afraid if I went lower the opamps would self-oscillate when the pot was in the max.gain position) and was done with it. Still I can hear no difference in bypass and engaged mode when all pots are in the center, so maybe after all the gain controls aren't THAT sensitive.
And now I need a little help. ;D I'm not sure how to ground this thing. As you can see this case has an bare aluminium plane on the bottom, on which I drilled a hole and put a screw as a grounding point. However, this is only grounding the plane, and not the case. I have already installed another screw on the back of the case (can be seen in the photo, not too good though, it is next to the XLR connectors), but then the plane will be floating. If I connect the plane to chassis (from one screw to the other) will I get a ground loop? If I leave it like this it isn't safe, is it?