Toggle analog out in software?

[banzai]

Just wondering if this is possible: My setup could really benefit from a plug-in that would enable me to toggle the analog audio output on or off.

I have two separate stereo systems in the same room that I'd like the Squeezebox to drive. One is a simple, no effort system. The other is my full, hard-core audiophile system.

Simple System:
Squeezebox analog out straight to Paradigm Active/20s.
(self-amped speakers that switch on when a signal is detected).

Audiophile System:
Squeezebox digital out to external DAC, amp, and main B&W speakers.

The two systems can co-exist with the Squeezebox, but only if I can kill the analog out when I want to listen through my audiophile system (otherwise the Paradigm speakers will power up and also start playing).

I can just physically switch off the Paradigms but it'd be dang slick if I could do it all from the comfort of my easy chair.

Assuming the hardware/firmware can support this, I'd suggest the following default behavior:

- On button always resets analog audio to "On" (otherwise people will inevitably forget which state they left it in and will start complaining that it's broken).

[JJZolx]

Just wondering if this is possible: My setup could really benefit from a plug-in that would enable me to toggle the analog audio output on or off.
There's a (player?) setting that makes the digital out volume independant of the analog out volume. This is what you generally want anyway if you're going to control the volume of the SB->DAC system through that system's volume control. Once this is set then all you'd do is turn down the SB's volume to zero.

[banzai]

Ah, excellent!

I'll have to look at the plugin API, if there's something equivalent to an onPowerOff event, I could write a really simple plugin that would:

- Activate "Digital-only mode" (aka set volume to zero)
- onPowerOff restore analog volume (to return to a nice default state).

It's so simple that it's barely worth writing. But the effort of writing it should eventually yield dividends over all that strenuous volume lowering and raising...

Also I wonder if setting the volume to zero electrically "quiets" the onboard DACs. I'm sure there'll be some audiophiles out there that swear the digital out sounds better w/volume at zero.

[opaqueice]

Also I wonder if setting the volume to zero electrically "quiets" the onboard DACs. I'm sure there'll be some audiophiles out there that swear the digital out sounds better w/volume at zero.

I tried that, just to see, and couldn't hear any difference :-).

Which B&W's do you have? I've got a pair of CM4 floorstanders I'm very happy with.

[banzai]

Heh, I'm not surprised. The only time I've heard a difference between digital sources was when one of them was using an analog audio cable for the S/PDIF signal. Analog cables are out of spec for digital signals and lose parts of the signal (sounds like a really poorly compressed MP3).

With a proper digital signal cable (same as standard video cables), I haven't heard a difference. I'll admit though that I haven't been as obsessive-compulsive at testing digital sources as some audiophiles, so I won't say that the digital source makes NO difference.

One audiophile thing that does make a big difference is power, at least for DACs and amps. I just upgraded the power cables in my system and added PS Audio UPC-200 line conditioners. The changes have been instantly noticeable, significant, and wonderful.

I'm running B&W 703 floorstanders as my mains. They are just sumptuous. And gorgeous to look at as well. I have B&W 602 s3 bookshelfs as my surrounds and they're actually *shockingly* good, especially considering their price. They're 20% the cost of the 703s but they give you much more than 20% the sound. I'd ballpark it closer to 80%. Might be the best bargain in affordable sound.

[seanadams]

Also I wonder if setting the volume to zero electrically "quiets" the onboard DACs.


IIRC setting the preamp control to maximum attenuation will effect a partial shutdown of the DAC, lowering the noise level a bit below what you'd get otherwise get playing "all zeroes". This may be useful for some auto-sensing amplifiers which require a lower noise level to think that the source is "off". There was some discussion of this a while ago and I thought a feature request was entered (related to s/pdif shutoff request), but I can't find it now...

[banzai]

IIRC setting the preamp control to maximum attenuation will effect a partial shutdown of the DAC, lowering the noise level a bit below what you'd get otherwise get playing "all zeroes". This may be useful for some auto-sensing amplifiers which require a lower noise level to think that the source is "off". There was some discussion of this a while ago and I thought a feature request was entered (related to s/pdif shutoff request), but I can't find it now...

Any updates on this feature request? The analog outs are not quiet enough to shut down the Paradigm Active/20s. As long as the SB is connected to the speakers' analog ins, they think there's a signal coming through (even when the SB is in its "off" mode).

This may have more to do with noise/interference that creeps into the analog outs. I have to do more experimenting, but I've noticed that my right speaker (which is close to the SB) emits a bit of a high-pitched tone when connected to the SB analog out.

The headphone output is also plauged by similar noise.

I'll create a separate post to see if others have the same issue or if maybe this is just a hardware problem in my SB.

[seanadams]

Any updates on this feature request? The analog outs are not quiet enough to shut down the Paradigm Active/20s. As long as the SB is connected to the speakers' analog ins, they think there's a signal coming through (even when the SB is in its "off" mode).

This may have more to do with noise/interference that creeps into the analog outs. I have to do more experimenting, but I've noticed that my right speaker (which is close to the SB) emits a bit of a high-pitched tone when connected to the SB analog out.

The headphone output is also plauged by similar noise.

I'll create a separate post to see if others have the same issue or if maybe this is just a hardware problem in my SB.

No news on this feature request, but I don't think this is related to your right channel issue. Both channels should have practically identical noise floors.

[cbemoore]

The original bug (disabling SPDIF output when the Squeezebox is put into standby) is here:

http://bugs.slimdevices.com/show_bug.cgi?id=1397

There was an additional issue - the analog out has a high noise floor when the Squeezebox is in standby. This noise floor is in the inaudible frequency range (so there's no audible problem), but it stops my active monitors from powering off automatically!

Sean did some tests, and found that if he disabled the DAC at the same time as disabling SPDIF output, this noise is removed:

http://forums.slimdevices.com/showpost.php?p=52669&postcount=46

This issue has been added to bug 1397 (see comment 11 by Sean). So the desired behaviour is that when the Squeezebox is put into standby, the SPDIF output should be disabled and the DAC should also be disabled.

I've been eagerly waiting for this bug to be fixed, but I haven't heard anything in months. Hopefully this will refresh someone's memory!!

Cheers
Chris

[cbemoore]

Any updates on this feature request? The analog outs are not quiet enough to shut down the Paradigm Active/20s. As long as the SB is connected to the speakers' analog ins, they think there's a signal coming through (even when the SB is in its "off" mode).

You have the exact same issue as me.

My Mackie monitors power down automatically when the input signal is lower than -74dBu. According to Sean's tests (see the link in my previous post) the Squeezebox's noise floor is -60dBu when the DAC is active. If the DAC is disabled, the noise floor will go down to -90dBu, which should be low enough for my monitors to power down correctly.

Can you add a vote for bug 1397 ? The more people that vote, the more likely it is that the bug will get fixed....

Cheers
Chris

[banzai]

You have the exact same issue as me.

...

Can you add a vote for bug 1197 ? The more people that vote, the more likely it is that the bug will get fixed....

Done. Vote is logged.

Shutting down the digital out might also help my DAC. It's an old Proceed DSD and since I got the SB3 the DAC has been much flakier than usual. A couple times this week I turned on the DAC and it couldn't lock to any of the digital inputs. I've only seen that happen once or twice before, but since the SB3 it's happened about four times (and I've only had the SB3 hooked up for about 2 weeks now). I thought the DAC needed to go (back!) in for service.

[Wombat]

Done. Vote is logged.

Shutting down the digital out might also help my DAC. It's an old Proceed DSD and since I got the SB3 the DAC has been much flakier than usual. A couple times this week I turned on the DAC and it couldn't lock to any of the digital inputs. I've only seen that happen once or twice before, but since the SB3 it's happened about four times (and I've only had the SB3 hooked up for about 2 weeks now). I thought the DAC needed to go (back!) in for service.
May it be you connect the Squeey via Coaxial? I had noise using the switching power supply. That means some garbage creeps over. Can you try an optical link if it still behaves this way? Or even better a linear power supply?

[tonyptony]

Been reading this thread with great interest. I don't want to complicate things, but I will. :) Would it be possible to create a variant of this bug request that would shut down the DAC, but leave the digital out running? It sounds to me like if there's a way to shut down the analog section only, there could be some improvement on the digital side. I don't use the analog outs on my SB3 (don't even have them connected). Just use it to feed my external DAC. Anything that could be done to optimize the digital signal would be great!

[cbemoore]

It sounds to me like if there's a way to shut down the analog section only, there could be some improvement on the digital side.

What makes you think that??

[Phil Leigh]

...because in general, the shutting down of anything extraneous that draws current and/or might inject noise can only ever help? If you don't need the analogue circuit, turning it off could only be better in theory for the digital signal. However, whether or not this makes a noticeable difference is highly debateable.

[banzai]

May it be you connect the Squeey via Coaxial? I had noise using the switching power supply. That means some garbage creeps over. Can you try an optical link if it still behaves this way? Or even better a linear power supply?

That's an interesting idea. I generally try to avoid optical connections but it's worth a try if the SB keeps giving the DAC problems.

[cbemoore]

Any updates on this feature request? The analog outs are not quiet enough to shut down the Paradigm Active/20s. As long as the SB is connected to the speakers' analog ins, they think there's a signal coming through (even when the SB is in its "off" mode).

Try the new firmware 64 (released yesterday), and set the "disable audio outputs when off" option. It now works perfectly with my Mackie HR624 monitors.

Chris