Testing Transporter for Digital Attenuation (Take II)

[mswlogo]

Don't read too much into absolute dynamic range differences between two tests. I think if was more patient with levels. I could have brought the Meridian up a tad. I got better at as I went along.

The Merdian has less effect than the Transporter. Both are pretty small but they do exist.

My Conclusion. Personally I'd never use it on anything. But Replay Gain would be pretty small (-12dB/+6dB). But as Volume control which typicaly needs more range, never in million years would I personally us it.

This is the Meridian Test adding digital attenution with Transporter and Bringing Levels back up with Analog knob on Merdian and remeasuring leaving TASCAM fixed.

http://meridianunplugged.com/downloa...Comparison.htm

This is the Transporter Test adding digital attenution with Transporter and Bringing Levels back up with Analog knob input Gain on TASCAM.

http://meridianunplugged.com/downloa...Comparison.htm

I came up with better test

http://meridianunplugged.com/downloa...Comparison.htm

For more comments about see this post

http://forums.slimdevices.com/showpo...56&postcount=8

[darrenyeats]

This is the Meridian Test adding digital attenution with Transporter and Bringing Levels back up with Analog knob on Merdian and remeasuring leaving TASCAM fixed.

http://meridianunplugged.com/downloa...Comparison.htm

This is the Transporter Test adding digital attenution with Transporter and Bringing Levels back up with Analog knob input Gain on TASCAM.

http://meridianunplugged.com/downloa...Comparison.htm

I'm surprised about the amount of dynamic range lost at -24db by a TP in this test.

Looking deeper however...the first 6db of attenuation shows just 0.1db of dynamic range lost, the next 6db shows 1db lost, the next 12db shows 6db lost. This is exactly the pattern I would expect to see. Where the 16 bit quantisation noise is dominating, increasing the DAC noise doesn't impact much. As you attenuate more DAC noise starts to impact and then finally it accelerates because the DAC noise starts to dominate performance.

A Benchmark DAC1 would perform better. Looks like the Meridian DACs perform better too?

To my mind the results show digital volume can be used in the right circumstances.

Thanks for these tests mswlogo.
Darren

[darrenyeats]

mswlogo;544715 Wrote:
>
> This is the Meridian Test adding digital attenution with Transporter
> and Bringing Levels back up with Analog knob on Merdian and remeasuring
> leaving TASCAM fixed.
>
> http://meridianunplugged.com/downloa...Comparison.htm
>
> This is the Transporter Test adding digital attenution with Transporter
> and Bringing Levels back up with Analog knob input Gain on TASCAM.
>
> http://meridianunplugged.com/downloa...Comparison.htm
I'm surprised about the amount of dynamic range lost at -24db by a TP
in this test.

Looking deeper however...the first 6db of attenuation shows just 0.1db
of dynamic range lost, the next 6db shows 1db lost, the next 12db shows
6db lost. This is exactly the pattern I would expect to see. Where the
DAC noise is so low compared to 16 bit quantisation noise, increasing
the DAC noise doesn't impact much. As you go further down it starts to
impact and then finally it accelerates.

A Benchmark DAC1 would perform better. Looks like the Meridian DACs
perform better too?

To my mind the results show digital volume can be used in the right
circumstances.
Darren


--
darrenyeats

http://www.amazon.co.uk/gp/richpub/l...606506-5721503.

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[Phil Leigh]

Don't read too much into absolute dynamic range differences between two tests. I think if was more patient with levels. I could have brought the Meridian up a tad. I got better at as I went along.

The Merdian has less effect than the Transporter. Both are pretty small but they do exist.

My Conclusion. Personally I'd never use it on anything. But Replay Gain would be pretty small (-12dB/+6dB). But as Volume control which typicaly needs more range, never in million years would I personally us it.

This is the Meridian Test adding digital attenution with Transporter and Bringing Levels back up with Analog knob on Merdian and remeasuring leaving TASCAM fixed.

http://meridianunplugged.com/downloa...Comparison.htm

This is the Transporter Test adding digital attenution with Transporter and Bringing Levels back up with Analog knob input Gain on TASCAM.

http://meridianunplugged.com/downloa...Comparison.htm

Mswlogo,
A couple of points:
1) one one of your tests you have left/right channels reversed at your soundcard input - hence the crosstalk of -6dB!

2) You and I are applying completely different methodologies... you are using the Meridian to apply make-up gain when you lower the TP volume. I'm not, so I am recording at a lower input level to the soundcard each time. If you really were using the digital volume control as a volume control, you wouldn't alter the Meridian level! You would set the Meridian to the loudest volume you wanted to ever use and then alter day-to-day vol with the TP level - for critical listening rather than background playing this would almost certainly be in the 0-12 range of adjustment.

Note that by default RMAA normalises the level of the recorded file as it reads it...


3) I've just realised we are both making a minor schoolboy error in our use of RMAA :-).

When you play a redbook file (16/44.1) via TP or Touch DAC, the DACs are being driven at 24/44.1.

Therefore, to accurately capture the test we need to record the playback at 24/44.1.

The differences are slight as you would expect.
I've repeated my tests at 24/44.1.

[Phil Leigh]

mswlogo;544715 Wrote:
> Don't read too much into absolute dynamic range differences between two
> tests. I think if was more patient with levels. I could have brought
> the Meridian up a tad. I got better at as I went along.
>
> The Merdian has less effect than the Transporter. Both are pretty small
> but they do exist.
>
> My Conclusion. Personally I'd never use it on anything. But Replay Gain
> would be pretty small (-12dB/+6dB). But as Volume control which typicaly
> needs more range, never in million years would I personally us it.
>
> This is the Meridian Test adding digital attenution with Transporter
> and Bringing Levels back up with Analog knob on Merdian and remeasuring
> leaving TASCAM fixed.
>
> http://meridianunplugged.com/downloa...Comparison.htm
>
> This is the Transporter Test adding digital attenution with Transporter
> and Bringing Levels back up with Analog knob input Gain on TASCAM.
>
> http://meridianunplugged.com/downloa...Comparison.htm

Mswlogo,
A couple of points:
1) you have left/right channels reversed at your soundcard input -
hence the crosstalk of -6dB!

2) You and I are applying completely different methodologies... you are
using the Meridian to apply make-up gain when you lower the TP volume.
I'm not, so I am recording at a lower input level to the soundcard each
time each time. If you really were using the digital volume control as a
volume control, you wouldn't alter the Meridian level! You would set the
Meridian to the loudest volume you wanted to ever use and then alter
day-to-day vol with the TP level - for critical listening rather than
background playing this would almost certainly be in the 0-12 range of
adjustment.


3) I've just realised we are both making a minor schoolboy error in our
use of RMAA :-).

When you play a redbook file (16/44.1) via TP or Touch DAC, the DACs
are being driven at 24/44.1.

Therefore, to accurately capture the test we need to record the
playback at 24/44.1.

The differences are slight as you would expect.
I've repeated my tests at 24/44.1.


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--
Phil Leigh

You want to see the signal path BEFORE it gets onto a CD/vinyl...it
ain't what you'd call minimal...
Touch(wired/XP) - 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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[Phil Leigh]

That all of the results in this thread include the contribution of the respective ADC's in the "soundcards" being used to do the measurements.

Be wary of comparing (too closely) my results with mswlogo's as we have different ADC's, different cables, different sources and different chains.

One thing is clear though - the Touch is amazingly good value for money on the criteria being measured here!

[Phil Leigh]

That all of the results in this thread include the contribution of the
respective ADC's in the "soundcards" being used to do the
measurements.

Be wary of comparing (too closely) my results with mswlogo's as we have
different ADC's, different cables, different sources and different
chains.

One thing is clear though - the Touch is amazingly good value for money
on the criteria being measured here!


--
Phil Leigh

You want to see the signal path BEFORE it gets onto a CD/vinyl...it
ain't what you'd call minimal...
Touch(wired/XP) - 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
------------------------------------------------------------------------
Phil Leigh's Profile: http://forums.slimdevices.com/member.php?userid=85
View this thread: http://forums.slimdevices.com/showthread.php?t=78477

[mswlogo]

I understand what you are saying.

I've used REW (all live) and it is extremely fussy of always calibrating levels for everything.

When I use Live Testing with RMAA (which in many cases works fine) the software requires you calibrate levels for each test.

But the results may be a little more stable doing what you suggested.

I'll give a go.

[mswlogo]

I understand what you are saying.

I've used REW (all live) and it is extremely fussy of always
calibrating levels for everything.

When I use Live Testing with RMAA (which in many cases works fine) the
software requires you calibrate levels for each test.

But the results may be a little more stable doing what you suggested.

I'll give a go.


--
mswlogo

XP > Cat5 > Transporter/DuetController > SPDIF > Meridian G68 > DSP6000,
DSP5500HC, DSP5000
XP > Cat5 > SB3 > SPDIF > Meridian DSP5000
XP > Cat5 > DuetReceiver > SPDIF > Meridian G91 > DSP5000

'My Transporter Setup'
(http://forums.slimdevices.com/showpo...1&postcount=45)
'Hitch Hikers Guide to Meridian' (http://www.meridianunplugged.com)
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[mswlogo]

I did the test the way phil suggested. And results were worse. So bad that the -24dB analyze could not find sync pulse.

I understand why you want to do it this way but I think it's not right.

You are stressing the ADC on sound card but not stressing the sound card peeamp gain by leaving it fixed.

The way I did it I'm feeding similar levels to ADC but I'm stressing the input gain preamp on sound card. I believe the analog circiuts are more stable

What I'm looking for is, regardless of how good your analog side is or gain, what does the DAC lose by shifting it's bits lower. Note that folks that use it as volume have Full gain on analog side.

I figured out a good test that really sees the effects of digital attenuation that removes effect of preamp input gain on sound card but still gives same levels to adc on sound card.

Run the test signal and attenuate it by say 12dB digitally. Record it at full scale as best you possibly can. Fine tuning everything.

Now switch how you attenuated. Put digital back up to 0dB and attenuate in analog by 12dB. That's exact what we want to compare.

Preamp gain stays the same (may need a tiny tweak). Levels that reach adc will also be the same.

The only difference is how we attenuated. This is exactly what we want to compare.

I ran the test but have not had a chance to post it yet.