T Attenuator Termination Kluge

Where we discuss new analog design ideas for Pro Audio and modern spins on vintage ones.
Gold
Posts: 584
Joined: Sat Dec 01, 2007 6:20 pm

Re: T Attenuator Termination Kluge

Post by Gold » Fri Oct 11, 2019 1:58 pm

Damn, foiled again.The attenuators need the 5K termination for accurate gain steps.

Gold
Posts: 584
Joined: Sat Dec 01, 2007 6:20 pm

Re: T Attenuator Termination Kluge

Post by Gold » Sat Oct 12, 2019 11:27 am

I kept banging away at this. I had each channels signal and common wires tied together at a few points with lacing twine. I didn’t have the channel bundles tied together. I separated the wires and saw a 1dB improvement in the cut. Yesterday I was seeing -79dBu on left channel and -76dBu on the right channel of both the preview and program channels.

I tried shielding the signal wires of Right Preview. I got a 4dB improvement to -80dBu. I did the same thing to the Left Preview and got a 2dB improvement to -81dBu. Shielding the wires evened out the 3dB discrepancy to 1dB. I’ll take it. I still get cut below the measurement range with the attenuators at zero attenuation.

Gold
Posts: 584
Joined: Sat Dec 01, 2007 6:20 pm

Re: T Attenuator Termination Kluge

Post by Gold » Wed Oct 16, 2019 1:48 pm

Complete unit. I've started mounting all PCB's on rails attached to the sides of the chassis. This allows access from the top and bottom.

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