Re: [slim] Does digital volume control cost resolution?

2010-02-13 Thread KMorgan

So did I accidently get it right when I said (with regard to a 16 bit
sample bumped up to 24)

 Remove all the [extra] 0s and the level will now be 1/256 with no loss
 in resolution. You're just back where you started. Since whole number
 multiplication does not have any effect on resolution then the original
 signal can be kept intact as long as the digital level control is kept
 to a multiple of 1/256.

From what I can glean, SB does indeed stick to increments of 1/256.

K


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Re: [slim] Does digital volume control cost resolution?

2010-02-13 Thread DaveWr

In the attached thread, P Dixon explains that 1/256 or multiples are
used down to -30db.  In the old 40 step volume days (2005) he had to
argue with Sean  Dean to get it corrected to be this way). Further
volume reduction after that bit resolution accuracy is compromised.

http://forums.slimdevices.com/showthread.php?t=28133highlight=volume+stepspage=2

The thing I don't know is whether replaygain (if used) also follows
these adjustment rules to protect bit resolution.

Dave


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Re: [slim] Does digital volume control cost resolution?

2010-02-12 Thread bobkoure

seanadams;164681 Wrote: 
 ...
 This has been discussed many times here, but I won't refer you to our
 archives as there have been far too many people still getting it wrong.
 Instead, here's a detailed and correct explanation from Lavry (login
 needed):
 
 http://lavryengineering.com/lavry_forum/login.php?redirect=viewtopic.phpt=76
 

Lavry seems to have changed their forum. Did anyone save this offsite,
or have a new link?
Thanks!


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Re: [slim] Does digital volume control cost resolution?

2010-02-10 Thread bobkoure

Seems like maybe the gist of Sean's response should go into the wiki?


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Re: [slim] Does digital volume control cost resolution?

2010-02-10 Thread gdg

Phil Leigh;514804 Wrote: 
 The SB3 uses a 24-bit internal implementation for it's level control.
 Provided you keep the volume fairly high you shoudn't notice too much
 loss of resolution.

I can't find the post where Sean addressed this but I just want to be
sure I understood...

Since for each 6db of attenuation one loses 1 bit does that mean that I
can afford 48 db of digital attenuation (in the SB3) on a 16 bit source
before I lose resolution?


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Re: [slim] Does digital volume control cost resolution?

2010-02-10 Thread Phil Leigh

gdg;515891 Wrote: 
 I can't find the post where Sean addressed this but I just want to be
 sure I understood...
 
 Since for each 6db of attenuation one loses 1 bit does that mean that I
 can afford 48 db of digital attenuation (in the SB3) on a 16 bit source
 before I lose resolution?

It's got nothing to do with losing resolution in an absolute sense -
you still have 16/20+ bits. It's the value in them that is changing and
thus the max SNR and dynamic range.
You really need to read this thread fully - especially Sean's
comments.

http://forums.slimdevices.com/showpost.php?p=164666postcount=1

In practice you can wind the volume down to 70/80 out of 100 without
suffering any noticeable effects.


-- 
Phil Leigh

You want to see the signal path BEFORE it gets onto a CD/vinyl...it
ain't what you'd call minimal...
SB Touch Beta (wired) - TACT 2.2X (Linear PSU) + Good Vibrations S/W -
MF Triplethreat(Audiocom full mods) - Linn 5103 - Aktiv 5.1 system (6x
LK140's, ESPEK/TRIKAN/KATAN/SEIZMIK 10.5), Townsend Supertweeters, Blue
Jeans Digital,Kimber Speaker  Chord Interconnect cables
Kitchen Boom, Outdoors: SB Radio

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Re: [slim] Does digital volume control cost resolution?

2010-02-10 Thread DaveWr

gdg;515891 Wrote: 
 I can't find the post where Sean addressed this but I just want to be
 sure I understood...
 
 Since for each 6db of attenuation one loses 1 bit does that mean that I
 can afford 48 db of digital attenuation (in the SB3) on a 16 bit source
 before I lose resolution?

I hope this helps, if you want further details search for Patrick Dixon
+ Volume

http://forums.slimdevices.com/showthread.php?t=28834highlight=Volume+control

Dave


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Re: [slim] Does digital volume control cost resolution?

2010-02-10 Thread gdg

Phil Leigh;515894 Wrote: 
 It's got nothing to do with losing resolution in an absolute sense -
 you still have 16/20+ bits. It's the value in them that is changing and
 thus the max SNR and dynamic range.
 You really need to read this thread fully - especially Sean's
 comments.
 
 http://forums.slimdevices.com/showpost.php?p=164666postcount=1
 
 In practice you can wind the volume down to 70/80 out of 100 without
 suffering any noticeable effects.

Thanx Phil,
I followed the discussion and Sean gives the best layperson explanation
I've heard in the many years I've been trying to sort this out. The
biggest problem (I think) is that people don't clarify that there are 2
issues:
1) signal to noise (dynamic range) which goes down with any level of
attenuation and...
2) bit resolution

Sean clarified this nicely. 
Thanx again for the patient guidance.


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Re: [slim] Does digital volume control cost resolution?

2010-02-08 Thread Soulkeeper

So in other words, you control the volume by choking the DAC, and you
need to keep the SB volume on 100% in order to get full resolution? 

There is no volume controlling amp/circuit after the DAC? 

Is this the case for all SB models?


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Re: [slim] Does digital volume control cost resolution?

2010-02-08 Thread KMorgan

Having nothing better to do I've been pondering this.

If a 16bit source is made up to 24bit by adding eight 0s on the end,
then isn't it fair to say that there will be no loss of resolution if
all you do is remove a few of them?  Of course the signal will be closer
to the noise floor, but what about resolution?  e.g. (assuming 50%
digital level control = an arithmetic division by 2) then simply
removing one of the 0s will not reduce resolution.

Is the level control arithmetic?

Take this a bit further.  Remove all the 0s and the level will now be
1/256 with no loss in resolution. You're just back where you started.
Since whole number multiplication does not have any effect on resolution
then the original signal can be kept intact as long as the digital level
control is kept to a multiple of 1/256.

Perhaps the volume control should be made and marked as 1/256 -
256/256, or at least do that in the background. In whole number % terms
you only hit one of these magic numbers at 25, 50, 75, 100%. Any
intermediate volume will introduce rounding errors.  At the top end
there will be eight spare bits to accomodate this, at the lower end this
will be less.

So does an arithmetic volume of 75% have better resolution than, say,
95%?

Please note the Numpty Warning at the top.  Please assist by spotting
the logical/technical whoopsie.  Looking forward to being set straight
:)

Keith


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Re: [slim] Does digital volume control cost resolution?

2010-02-08 Thread DaveWr

You have already been through this debate before

Just search for Sean Adams + Volume Control  you will find the answers
to you questions - as you previously posed them.

For further complex data Patrick Dixon + Volume Control will explain
all the issues about the arithmetic calculations an effects on
resolution.

Dave


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Re: [slim] Does digital volume control cost resolution?

2010-02-08 Thread Phil Leigh

Soulkeeper;515106 Wrote: 
 So in other words, you control the volume by choking the DAC, and you
 need to keep the SB volume on 100% in order to get full resolution? 
 
 There is no volume controlling amp/circuit after the DAC? 
 
 Is this the case for all SB models?


The use of the SB volume control is optional.
The control operates in the digital domain, by changing the bits sent
to the DAC or spdif

The idea is to run your SB device into a setup that has correct gain
staging.
This means that you should have an active or passive preamp with level
control between SB and amp/speakers. You then don't NEED to use the SB
control at all.

Alternatively use in-line attenuators into just a power amp to lower
the level to the loudest you ever want to hear and then use the SB
control for day-to-day tweaking of level. This way, you will generally
never lower the control enough for loss of resolution to be a big
issue.

With the 24-bit control and a 16-bit original signal (say redbook CD),
any lowering will at minimum impact the value of the 16th original bit -
this is why HDCD won't be passed correctly via SPDIF unless vol is on
MAX and replaygain is disabled.


There's nothing really bad about (24-bit+) digital level control when
used wisely.

Sean has explained the ins and outs of digital level control several
times - it's in the Audiophile forum.


-- 
Phil Leigh

You want to see the signal path BEFORE it gets onto a CD/vinyl...it
ain't what you'd call minimal...
SB Touch Beta (wired) - TACT 2.2X (Linear PSU) + Good Vibrations S/W -
MF Triplethreat(Audiocom full mods) - Linn 5103 - Aktiv 5.1 system (6x
LK140's, ESPEK/TRIKAN/KATAN/SEIZMIK 10.5), Townsend Supertweeters, Blue
Jeans Digital,Kimber Speaker  Chord Interconnect cables
Kitchen Boom, Outdoors: SB Radio

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Re: [slim] Does digital volume control cost resolution?

2010-02-08 Thread KMorgan

DaveWr;515115 Wrote: 
 For further complex data Patrick Dixon + Volume Control will explain all
 the issues about the arithmetic calculations an effects on resolution.

Thanks

K


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Re: [slim] Does digital volume control cost resolution?

2010-02-08 Thread gdg

Phil Leigh;514804 Wrote: 
 The SB3 uses a 24-bit internal implementation for it's level control.
 Provided you keep the volume fairly high you shoudn't notice too much
 loss of resolution.

Since for each 6db of attenuation one loses 1 bit does that mean that I
can afford 48 db of digital attenuation on a 16 bit source before I lose
resolution?


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Re: [slim] Does digital volume control cost resolution?

2010-02-08 Thread gdg

I just noticed, after reading some of the responses that my question has
been answered in another thread by Sean Adams. Thanx for indulging me.


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Re: [slim] Does digital volume control cost resolution?

2010-02-07 Thread Phil Leigh

The SB3 uses a 24-bit internal implementation for it's level control.
Provided you keep the volume fairly high you shoudn't notice too much
loss of resolution.


-- 
Phil Leigh

You want to see the signal path BEFORE it gets onto a CD/vinyl...it
ain't what you'd call minimal...
SB Touch Beta (wired) - TACT 2.2X (Linear PSU) + Good Vibrations S/W -
MF Triplethreat(Audiocom full mods) - Linn 5103 - Aktiv 5.1 system (6x
LK140's, ESPEK/TRIKAN/KATAN/SEIZMIK 10.5), Townsend Supertweeters, Blue
Jeans Digital,Kimber Speaker  Chord Interconnect cables
Kitchen Boom, Outdoors: SB Radio

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Re: [slim] Does digital volume control cost resolution?

2010-02-07 Thread m1abrams

Phil Leigh;514804 Wrote: 
 The SB3 uses a 24-bit internal implementation for it's level control.
 Provided you keep the volume fairly high you shoudn't notice too much
 loss of resolution.

If you notice a loss in resolution with such a low level then maybe you
should not use so much gain ;)


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