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Topic: RMAF 2009 and " a new form of measurement" (Read 20985 times) previous topic - next topic
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RMAF 2009 and " a new form of measurement"

Reply #25 –
There seems to be a long tradition in the UK of designing products and then switching to writer mode and reviewing them. I think its based on the politician/lobbyist career model. Remember that journalism doesn't pay well (like public service). After seeing him present he has much more potential on the Infomercial circuit . . .

RMAF 2009 and " a new form of measurement"

Reply #26 –
I just read this thread and have to say, the level of smugness seems to have reached an all-time high!  Be careful, those who think they know everything, are usually not looking hard enough.....

RMAF 2009 and " a new form of measurement"

Reply #27 –
Care to demonstrate that you can engage in a technical conversation, or are you just taking a cowardly swipe?

RMAF 2009 and " a new form of measurement"

Reply #28 –
Quote from: daiku on
I just read this thread and have to say, the level of smugness seems to have reached an all-time high!  Be careful, those who think they know everything, are usually not looking hard enough.....

I am not sure one needs anything other than a cursory glance at the presentation to know what is going on. It is marketing of a form that has been seen for over 3 decades by all the major cable companies and many of the minor companies. In order to sell cables to audiophiles they need to distinguish their product from the competition and provide that aura necessary for all very expensive luxury products. This is what they are doing and good luck to them.

For anyone with a school level or above understanding of science, I am afraid it is hard to see it as anything other than a mild source of amusement. This group is of course completely irrelevant to audiophile cable companies and, to a very large extent, the whole audiophile industry.

RMAF 2009 and " a new form of measurement"

Reply #29 –
Quote from: honestguv on
I am not sure one needs anything other than a cursory glance at the presentation to know what is going on. It is marketing of a form that has been seen for over 3 decades by all the major cable companies and many of the minor companies. In order to sell cables to audiophiles they need to distinguish their product from the competition and provide that aura necessary for all very expensive luxury products. This is what they are doing and good luck to them.
For anyone with a school level or above understanding of science, I am afraid it is hard to see it as anything other than a mild source of amusement. This group is of course completely irrelevant to audiophile cable companies and, to a very large extent, the whole audiophile industry.

Andy, is that you?
Loudspeaker manufacturer

RMAF 2009 and " a new form of measurement"

Reply #31 –
Quote from: WernerO on
Haven't read it yet, so I don't know its fun factor.
I just had a quick look. AFAIK the basic idea is to use an ADC to record the analogue output of an audio device or chain and investigate if modifications in the chain result in (significant) different ADC data.
Basically I think this test can work well, but it's rather tricky to set up correctly. In the paper I can't find any reference to how the ADC clock was locked to the DAC (CD?) output. If DAC and ADC are not locked, a difference test will be meaningless. Have I missed something ?
 

RMAF 2009 and " a new form of measurement"

Reply #32 –
They don't mention any synchronisation of DAC and ADC.

The refernence signal all comparison is against are the raw digital-domain data
off a CD, in a 44.1kHz space.

They never establish the CD/DAC/ADC clocking accuracy and stability relative to the 'perfect'
(or rather timeless) reference data.

The comparisons are between unreconstructed reference data, and captured
data at 44.1kHz after having passed through a commercial DAC and a commercial
recording ADC.

Both DAC and ADC very likely use half-band anti-imaging and anti-aliasing filters, so
they suffer incomplete suppression in the small band above (below) 22.05kHz.
As a result the captured data have to be contaminated with alias components in the
20-22.05kHz band.

They don't mention this, and they don't make allowance for it in the subsequent processing.

Before comparison reference and capture data are matched in amplitude and time, using least square techniques over the full waveform. Since the capture data have alias components added the summed-signal magnitude matching must be skewed. They presumably perform sub-sample time alignment, but do not explicitly state how reconstruction and anti-alias filtering are done in this step. From what I read I fear it is just linear interpolation (!).

The comparison itself seems to be done on, again, a linearly interpolated proxy of the sample streams.

In other words, there is no proper signal reconstruction going on, and their method considers the payload signal plus an amount of aliases and images folded around 22.05kHz.

They pride themselves in looking at the time domain, while ignoring the frequency domain. It figures.

With the above in mind the expected 'error signal' according to their method would be near-random (and artificially large). They claim that their measurements indicate the benefits of cables, platforms, dampers, ... but they never state how repeatable each such test is for a static setup.



Either the paper is massively simplifying things  in a very inappropriate way, or, even worse, the participants to this experiment are utterly clueless and would better stick to defence resp. conning audiophools.


It would be fun if they subjected a Wadia(*)  CD-player to this approach, followed with a public explanation of the measurement results versus how they rate that player subjectively.


(* For clarity, no offence to Wadia intended.)