Bug 3784 – Auto-sensing Power Amp will never switch off when Squeezebox is connected

Bug 3784 - Auto-sensing Power Amp will never switch off when Squeezebox is connected

Summary:

Auto-sensing Power Amp will never switch off when Squeezebox is connected

Status:	RESOLVED FIXED

Product:	SB 2/3
Classification:	Unclassified
Component:	Audio
Version:	59
Platform:	All All

Importance:	P2 enhancement (vote)
Target Milestone:	---
Assigned To:	Richard Titmuss

URL:
Keywords:

Depends on:
Blocks:
	Show dependency tree / graph

Reported:	2006-07-20 03:40 UTC by Chris
Modified:	2009-09-08 09:23 UTC (History)
CC List:	1 user (show)

See Also:
Category:	---

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Description Chris 2006-07-20 03:40:40 UTC

If an auto-sensing power amp is connected to the analog outputs of the SB2/SB3, the power amp will never turn off.

This is due to out of band noise emanating from the DAC, even when the DAC is processing all 0's.

As described in the following thread, this problem could be fixed by disabling the DAC when the SB2 is turned off:
http://forums.slimdevices.com/showpost.php?p=52669&postcount=46

Richard tried doing this while fixing bug 1397, but it was found that disabling the DAC caused a pop noise on the analog outputs. Therefore the feature was never released.

However, it would be really good if this feature could be implemented at some time in the future....

Comment 1 Blackketter Dean 2006-07-20 08:16:07 UTC

Chris: what model amp has this behavior for you?

Comment 2 Chris 2006-07-20 10:17:28 UTC

(In reply to comment #1)
> Chris: what model amp has this behavior for you?
> 

I'm actually using a pair of Mackie HR624 active monitors. They will automatically shut down after 5 minutes if the signal level is below -74dBu. I imagine lots of power amplifiers have similar behaviour.

From Sean's tests, the Squeezebox 2 outputs around -60dBu when the DAC is enabled, even when its not playing anything. So my Mackies never turn off. But this drops to around -90dBu when the DAC is disabled, which should be low enough.

Chris

Comment 3 Chris 2006-09-17 15:07:43 UTC

Hi Richard,

This problem is now completely fixed with the new firmware 64. So that's another bug to tick off the list!

Thanks for your hard work - much appreciated!

Chris

Comment 4 Richard Titmuss 2006-09-17 15:16:19 UTC

Chris, thanks for the feedback. Changing target to 6.5 so I remember to add this to the change log tomorrow.