I'm using my Sonos Port basically as a pre-amp, powered by an Acurus A150 2 channel amplifier, and an Adcom GCD-750 CD player. I'm getting really distorted sound.
I've tried taking the Source Level down to 1. I've played around with the EQ. Nothing is working. When I remove the Port and connect it to my volume controller, it sounds perfect.
Any suggestions?
Best answer by GuitarSuperstar
View originalCan someone from Sonos chime in here?
Why? Do you think they can offer better advice for this specific problem?
First time here. Saw it on a few threads done the way. Didn't mean to offend.
First time is a good reason/excuse. You will not get better support than what you are getting on this issue from anyone that I know of in Sonos that posts here. It probably won’t even be as good.
One reason why you see some high post counts among some users here is because Sonos is often not to be seen - or seen in time - on many threads here.
Really appreciate the perspective!
I was curious as to the nominal output level of the CD player’s RCA outputs, to see whether that could explain the behaviour.
Have you tried inserting your ‘ancient’ passive volume control between the CD player and the Port?
I haven't. I'm trying to think how I'd rig that. I'd still need the out to the Amplifier from the Port How would I wire the CDP and passive volume control?
You could independently test the Port’s Line-In, e.g. using the headphone output from a phone.
Jumping in because I did not see an answer to the quoted. This is an easy way to test the line in circuitry of the Port. Have you done that?
I have not. So I'd need an RCA(s) to single headphone jack?
Well, I’m assuming the control is either RCA-in/RCA-out, or it’s combined with an input selector so it’s multiple RCA-in with a single stereo RCA-out. You could post some more info if relevant.
Either way, you’d just connect the CD player to an input and run the control's output into the Port’s Line-In. Set the volume to full, then lower it until (hopefully) the distortion goes away.
I have not. So I'd need an RCA(s) to single headphone jack?
Yes.
I have not. So I'd need an RCA(s) to single headphone jack?
Yes.
Just went through my old cord box and I think that one got tossed in the last purge. Ugh.
Well, I’m assuming the control is either RCA-in/RCA-out, or it’s combined with an input selector so it’s multiple RCA-in with a single stereo RCA-out. You could post some more info if relevant.
Either way, you’d just connect the CD player to an input and run the control's output into the Port’s Line-In. Set the volume to full, then lower it until (hopefully) the distortion goes away.
Keeping the Port volume control on Variable?
Excellent. You can note -- or even mark -- the volume position on the passive control, then tuck it away somewhere safe out of sight.
I really appreciate your time and problem solving on this one. It was driving me crazy!
What did the volume control setting on the passive control need to be at?
What did the volume control setting on the passive control need to be at?
I just turned it up to full and adjusted via the volume control in the app. No distortion. I also have the Source Level at 1. I'm not sure if I should consider making that higher. Any experience in all these variables?
What did the volume control setting on the passive control need to be at?
I actually just tried backing it down a bit and adjusting the volume higher in the app and I think it's clearer
Excellent. You can note -- or even mark -- the volume position on the passive control, then tuck it away somewhere safe out of sight.
Maybe a dumb question-it's still best to keep this in Variable, correct? I've read people say that the sound quality is better in Fixed and I'm not sure if this current set up would enable that (or if you believe it really does improve the sound quality)
In general if you get the sound levels you desire without having the volume level on a Port in variable mode to be set at less the 50%, sound quality difference from Fixed mode will not be audible.
This is rather a digression, but I suspect you may be conflating a couple of issues.
On the digital out, a volume level of 25% or more ensures that truncation on the 24-bit S/PDIF doesn’t begin to erode the 16-bit resolution. On the other hand, when I tested it many moons ago I found that Port needed to be kept at 85% or less to stay away from the effects of the soft-knee limiter. In other words the 25-85% range appeared to be the sweet spot for the digital out when Variable.
As for the analog out, these digital output considerations don’t apply. A decent analog output level does of course help with the downstream SNR.
Here is an attenuator. My concern with this particular model is that it can physically stress the jacks unless you insert it between two cables.
As for the analog out, these digital output considerations don’t apply. A decent analog output level does of course help with the downstream SNR.
I just know that a combination of higher output level from the source and a lower volume level from the downstream amp gives better results than from the same sound levels obtained by a combination that is the opposite - where the source level is low but the amp volume is turned up to compensate. I am not sure if this practice is relevant where the downstream amp has no volume control but I suspect it may be and it can’t hurt I think.
I have also found that keeping the amp level low by keeping the source level high helps in reducing start up speaker thumps from amps that cause these.
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