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2004-08-24, 14:55
> -----Original Message-----
> From: developers-bounces (AT) lists (DOT) slimdevices.com
> [mailto:developers-bounces (AT) lists (DOT) slimdevices.com] On Behalf
> Of ron thigpen
> Sent: 24 August 2004 20:28
> To: Slim Devices Developers
> Subject: Re: [Developers] Volume control range
>
> robin-lists (AT) robinbowes (DOT) com wrote:
>
> > I went through the settings and read "If you choose to have a fixed
> > digital audio volume level, the analog outputs will have
> the highest
> > quality possible" so I selected this setting.
> >
> > What does this really mean? What actually happens?
>
> it means the volume gain curve for the analog outs is now different.

Well, yes, I understand that.

My question solicits a more technical answer (I have a degree in
Electroacoustics, my final year project covered digital signal processing,
and I have considerable experience as a sound engineer).

Why does fixing the digital output affect the analogue levels? Does fixing
the digital level cause attenuation of the analogue level, or is the
analogue output naturally low but normally amplified when the digital level
is not fixed?

> (after reducing the gain on your amp) try cranking the volume
> up to 40
> on the unit, using the remote. you may find that the last
> few numbers
> ramp up the volume from almost nothing to full on.

The last few numbers do indeed ramp up the volumw at an exponential rate but
the maximum level is nowhere the level I get when the digital output is not
fixed.

> i leave my SB at this setting and use the remote volume
> control of my receiver to control levels during a listening session.

Now, if I had an amp with a remote volume control I'd do the same!

My shopping list includes, among many other things, an outboard DAC and a
new amp with remote volume control.

R.
--
http://robinbowes.com

seanadams
2004-08-24, 21:55
The reason the sound quality is better in analog volume mode is because
we do not touch the digital bits in that mode, instead doing the volume
control AFTER the dac. You do not need especially golden ears to hear
this - the difference is notable with headphones when using the lower
volume levels. However, using analog gain has the disadvantage that
volume control can not work in that mode when using the s/pdif output,
which is why this is not the default behavior. Only "power users" in my
opinion, would want to "lock out" the digital gain control, which is
effectively what happens when you switch to analog volume control.

More info in this thread:

http://lists.slimdevices.com/archives/discuss/2004-January/024724.html

As far as why the curve doesn't sound quite natural in analog volume
mode - it's just because I haven't spent enough time fiddling with it
yet. If somebody wants to improve it, we will happily accept a patch.
Keep in mind though that headphones need a lot of resolution on the
lower end of the scale. We might even need to go to more than 40 bars
on the scale (or a choice of curves) in order to make this work
perfectly for every user.


On Aug 24, 2004, at 2:55 PM, <robin-lists (AT) robinbowes (DOT) com> wrote:

>> -----Original Message-----
>> From: developers-bounces (AT) lists (DOT) slimdevices.com
>> [mailto:developers-bounces (AT) lists (DOT) slimdevices.com] On Behalf
>> Of ron thigpen
>> Sent: 24 August 2004 20:28
>> To: Slim Devices Developers
>> Subject: Re: [Developers] Volume control range
>>
>> robin-lists (AT) robinbowes (DOT) com wrote:
>>
>>> I went through the settings and read "If you choose to have a fixed
>>> digital audio volume level, the analog outputs will have
>> the highest
>>> quality possible" so I selected this setting.
>>>
>>> What does this really mean? What actually happens?
>>
>> it means the volume gain curve for the analog outs is now different.
>
> Well, yes, I understand that.
>
> My question solicits a more technical answer (I have a degree in
> Electroacoustics, my final year project covered digital signal
> processing,
> and I have considerable experience as a sound engineer).
>
> Why does fixing the digital output affect the analogue levels? Does
> fixing
> the digital level cause attenuation of the analogue level, or is the
> analogue output naturally low but normally amplified when the digital
> level
> is not fixed?
>
>> (after reducing the gain on your amp) try cranking the volume
>> up to 40
>> on the unit, using the remote. you may find that the last
>> few numbers
>> ramp up the volume from almost nothing to full on.
>
> The last few numbers do indeed ramp up the volumw at an exponential
> rate but
> the maximum level is nowhere the level I get when the digital output
> is not
> fixed.
>
>> i leave my SB at this setting and use the remote volume
>> control of my receiver to control levels during a listening session.
>
> Now, if I had an amp with a remote volume control I'd do the same!
>
> My shopping list includes, among many other things, an outboard DAC
> and a
> new amp with remote volume control.
>
> R.
> --
> http://robinbowes.com
>
>

seanadams
2004-08-24, 22:40
addendum:

When I was adding this feature, I did nearly all of my testing for the
analog volume mode using headphones connected to the built-in 1/8"
connector, because this setup was where I felt the most practical
improvement was to be gained (pun intended).

Personally I like a *lot* of resolution on the low-end when using
headphones, so you'll find that this is reflected in the way the
feature works.

I admit that this is a subjective thing, and that my preference may
have no bearing whatsoever to what everyone else expects. I also admit
that the curve is still not quite perfectly to my liking, even for
headphones. So again, feel free to tweak the curve and submit a patch
(preferably allowing more than one curve to be chosen).

Sean

On Aug 24, 2004, at 9:55 PM, Sean Adams wrote:

>
> The reason the sound quality is better in analog volume mode is
> because we do not touch the digital bits in that mode, instead doing
> the volume control AFTER the dac. You do not need especially golden
> ears to hear this - the difference is notable with headphones when
> using the lower volume levels. However, using analog gain has the
> disadvantage that volume control can not work in that mode when using
> the s/pdif output, which is why this is not the default behavior. Only
> "power users" in my opinion, would want to "lock out" the digital gain
> control, which is effectively what happens when you switch to analog
> volume control.
>
> More info in this thread:
>
> http://lists.slimdevices.com/archives/discuss/2004-January/024724.html
>
> As far as why the curve doesn't sound quite natural in analog volume
> mode - it's just because I haven't spent enough time fiddling with it
> yet. If somebody wants to improve it, we will happily accept a patch.
> Keep in mind though that headphones need a lot of resolution on the
> lower end of the scale. We might even need to go to more than 40 bars
> on the scale (or a choice of curves) in order to make this work
> perfectly for every user.
>
>
> On Aug 24, 2004, at 2:55 PM, <robin-lists (AT) robinbowes (DOT) com> wrote:
>
>>> -----Original Message-----
>>> From: developers-bounces (AT) lists (DOT) slimdevices.com
>>> [mailto:developers-bounces (AT) lists (DOT) slimdevices.com] On Behalf
>>> Of ron thigpen
>>> Sent: 24 August 2004 20:28
>>> To: Slim Devices Developers
>>> Subject: Re: [Developers] Volume control range
>>>
>>> robin-lists (AT) robinbowes (DOT) com wrote:
>>>
>>>> I went through the settings and read "If you choose to have a fixed
>>>> digital audio volume level, the analog outputs will have
>>> the highest
>>>> quality possible" so I selected this setting.
>>>>
>>>> What does this really mean? What actually happens?
>>>
>>> it means the volume gain curve for the analog outs is now different.
>>
>> Well, yes, I understand that.
>>
>> My question solicits a more technical answer (I have a degree in
>> Electroacoustics, my final year project covered digital signal
>> processing,
>> and I have considerable experience as a sound engineer).
>>
>> Why does fixing the digital output affect the analogue levels? Does
>> fixing
>> the digital level cause attenuation of the analogue level, or is the
>> analogue output naturally low but normally amplified when the digital
>> level
>> is not fixed?
>>
>>> (after reducing the gain on your amp) try cranking the volume
>>> up to 40
>>> on the unit, using the remote. you may find that the last
>>> few numbers
>>> ramp up the volume from almost nothing to full on.
>>
>> The last few numbers do indeed ramp up the volumw at an exponential
>> rate but
>> the maximum level is nowhere the level I get when the digital output
>> is not
>> fixed.
>>
>>> i leave my SB at this setting and use the remote volume
>>> control of my receiver to control levels during a listening session.
>>
>> Now, if I had an amp with a remote volume control I'd do the same!
>>
>> My shopping list includes, among many other things, an outboard DAC
>> and a
>> new amp with remote volume control.
>>
>> R.
>> --
>> http://robinbowes.com
>>
>>

Denny Page
2004-08-24, 23:30
Hmm... stupid question: Does this mean with the volume turned all the
way up, that the output of the analog connectors should be the same
regardless of the analog or digital volume mode setting?

[My personal search is for best quality from the analog connectors, no
volume control needed.]

Denny

seanadams
2004-08-25, 00:09
Good question actually. I can't remember for sure OTOH - it's been a
while since I worked on this - but I think at max volume, the output
should be identical in either mode. Certainly there will be no digital
adjustment in either case.

On Aug 24, 2004, at 11:30 PM, Denny Page wrote:

> Hmm... stupid question: Does this mean with the volume turned all the
> way up, that the output of the analog connectors should be the same
> regardless of the analog or digital volume mode setting?
>
> [My personal search is for best quality from the analog connectors, no
> volume control needed.]
>
> Denny
>
>
>
>
>