Denon x4700 + minidsp ddrc88a Noise issue

[Vim1zn]

Hi.

Just hooked up a minidsp ddrc88 to a denon x4700
Running rca out of the denon into the ddrc and then balanced out of the ddrc into my emotiva xpa.
Seem to be getting some noise out the speakers as soon as the system is turned on. What am i not doing right? Any help would be appreciated please .

 

[nainokami]

Hi.

Just hooked up a minidsp ddrc88 to a denon x4700
Running rca out of the denon into the ddrc and then balanced out of the ddrc into my emotiva xpa.
Seem to be getting some noise out the speakers as soon as the system is turned on. What am i not doing right? Any help would be appreciated please .

I had the same issue with my XPA-7 and DDRC and ended up running unbalanced into the XPA to reduce the noise. I think the problem stems from the XPA having 29 dB gain on both balanced and unbalanced, giving 6 dB higher noise floor when running balanced with an additional 6dB being added by the DDRC outputting up to 8 Vrms in balanced mode. You can reduce the output gain of the DDRC by 6 dB to 4 Vrms by using the dip switches, but you still have 6 dB extra gain to deal with when using balanced.
I think the problem is also exacerbated by the fact that Dirac imposes a 8 dB gain reduction (I think), which has to be made up for in the output, further raising the noise floor of the DDRC ... I've learned to live with the hiss. Sadly.

 

[Vim1zn]

Thanks for the response. From looking at the manual i think it ships with the output gain already set at 4v rms. odd its only got this “ noise” out of the centre channel.

 

[nainokami]

You're right. My mistake about the default gain. I ended up using high gain unbalanced (2 Vrms) to find a compromise that would still drive the XPA to full power (ca. 1.5 V).
But I missed that it was only the center channel giving you issues. What kind of noise are you hearing? Static, hiss, hum or something different? I get a slight elevation in noise floor on channel 1 in my DDRC, but nothing significant, and most likely audible because of my speaker's sensitivity (99 dB/W).

 

[Vim1zn]

No worries, id say its a hum . You can hear it ever slightly from about 2-3m away but up close its pretty audible. Fronts are klipsch rp 8000 with rp 504 centre. It is odd that its only from the centre. I may move it tomorrow to another output and see if that makes a difference.