Audio Hiss Solved

[VE6WZ]

Using both K3 twin and Yaesu FTdx-9000d radios with RCC1258 units for a long time I have had a bad audio hiss even with the volume turned to zero.

Solution: Do NOT use audio CODEC with 12 bit. I now use audio quality 2 which is 16 bit.
I found that even higher quality settings using 12 bit will cause audio hiss. 16 bit all ok.

I'm posting this in case others have the same problem.

de steve ve6wz.

[cx6vm]

Hi Steve

thanks very much

just starting with remote and many things to improve. Is very noticeable the improvement changing from 12 to 16 bits!

73,
Jorge
CX6VM/CW5W

[n6ldj]

Thanks.  16-bit worked here as well.  I was using Quality-0, "A-Law 8 kHz" and we had hiss.   It came from the radio end, and I thought it was the radio generating this (one channel was speaker audio that might have had audio PA hiss, but the second audio channel was low-level [300 mV] discriminator audio from a Motorola XPR4550 mobile radio).  Both channels had equal hiss before the fix.   Both are now fixed.

I modified the second audio channel input (ring, not tip) on the radio end to make it high-impedance (>100k ohm) so it would not load down the discriminator line.  This channel still has a bit more hiss, but its more than tolerable.

N6LDJ