setting up ABX tests at home

setting up ABX tests at home

I want to set up an ABX test at home on different sources to see if I
can hear a difference. I am doing this for my own education and fun -
I don't want to start investing in SPL meters, switches gain
equalizers of other boxes.

The sources are a Panasonic discman, an arcam CD player a squeezebox,
and hopefully we will borrow a high end CD as well. I will obviously
do it in pairs. I will have a helper switch manually. All units can be
connected to my budget level integrated NAD 325 BEE and have a copy of
the same media source.

My problem is how to neutralize differences in volume without
investing in equipment I have no need for. I can think of four
strategies

1) For each test start with volume at 0 and have testers ask for
volume to be adjusted to level they like.

2) Have the helper randomly set volume each time

3) (Maybe) use a PC to measure volume - not sure how to do this but I
do have a cheap microphone and audacity on the PC which should show me
the volume level - I don't know how accurate this is.

Advice appreciated.

Steve

Re: setting up ABX tests at home

"Steve" <goldstarsteve@gmail . com > wrote in message
news:focmm502k1l@news1.newsguy . com

> I want to set up an ABX test at home on different sources
> to see if I can hear a difference. I am doing this for my
> own education and fun - I don't want to start investing
> in SPL meters, switches gain equalizers of other boxes.

Please see w w w .pcabx . com .

> The sources are a Panasonic discman, an arcam CD player a
> squeezebox, and hopefully we will borrow a high end CD as
> well. I will obviously do it in pairs. I will have a
> helper switch manually. All units can be connected to my
> budget level integrated NAD 325 BEE and have a copy of
> the same media source.

One big problem with real-time tests of various disc players is that in
addition to matching volume, you also have to time-synch the two players.
Otherwise, anybody with halfway working ears can figure out the identities
of the players in an ABX test by listening to the timing differences.

> My problem is how to neutralize differences in volume
> without investing in equipment I have no need for. I can
> think of four strategies

> 1) For each test start with volume at 0 and have testers
> ask for volume to be adjusted to level they like.
>
> 2) Have the helper randomly set volume each time

> 3) (Maybe) use a PC to measure volume - not sure how to
> do this but I do have a cheap microphone and audacity on
> the PC which should show me the volume level - I don't
> know how accurate this is.

PC' audio interfaces can with appropriate software help make up a cheap,
high resolution, wide-bandwidth, highly stable voltage measuring device, but
they have limited input voltage range and questionable calibration.

The good news is that when you do ABX, you're interested in the degree of
matching, not the absolutely precise voltage. So the calibration issue is
moot. That leaves you with the input voltage range problem. I've found that
a high quality 5 K ohm potentiometer can match up a PC sound card with a
wide variety of audio devices.

Re: setting up ABX tests at home

> Please seew w w .pcabx . com .
The training is very usefull. Thx!

>
> One big problem  with real-time tests of various disc players is that in
> addition to matching volume, you also have to time-synch the two players.
> Otherwise, anybody with halfway working ears can figure out the identities
> of the players in an ABX test by listening to the timing differences.

I am switching manually so why not have each passage from the
beginning or have my switcher go back a few seconds on the unit to be
switched to before switching?

> That leaves you with the input voltage range problem. I've found that
> a high quality 5 K ohm potentiometer can match up a PC sound card with a
> wide variety of audio devices.

I don't want to purchase HW esp when I don't even know how to
pronounce it let alone where to put it!

Re: setting up ABX tests at home

"Steve" <goldstarsteve@gmail . com > wrote in message
news:fof9i80sku@news3.newsguy . com
>> Please seew w w .pcabx . com .
> The training is very usefull. Thx!
>
>>
>> One big problem with real-time tests of various disc
>> players is that in addition to matching volume, you also
>> have to time-synch the two players. Otherwise, anybody
>> with halfway working ears can figure out the identities
>> of the players in an ABX test by listening to the timing
>> differences.

> I am switching manually so why not have each passage from
> the beginning or have my switcher go back a few seconds
> on the unit to be switched to before switching?

If you play each passage from the beginning, then you are commiting yourself
to what will turn out to be a highly insensitive test due to the excessive
time delays between hearing each alternative.

>> That leaves you with the input voltage range problem.
>> I've found that
>> a high quality 5 K ohm potentiometer can match up a PC
>> sound card with a wide variety of audio devices.
>
> I don't want to purchase HW esp when I don't even know
> how to pronounce it let alone where to put it!

Then I suggest that you obtain some experience with PCABX, before you try to
go it alone.

Re: setting up ABX tests at home

Steve wrote:
> I want to set up an ABX test at home on different sources to see if I
> can hear a difference. I am doing this for my own education and fun -
> I don't want to start investing in SPL meters, switches gain
> equalizers of other boxes.
>
> The sources are a Panasonic discman, an arcam CD player a squeezebox,
> and hopefully we will borrow a high end CD as well. I will obviously
> do it in pairs. I will have a helper switch manually. All units can be
> connected to my budget level integrated NAD 325 BEE and have a copy of
> the same media source.
>
> My problem is how to neutralize differences in volume without
> investing in equipment I have no need for. I can think of four
> strategies
>
> 1) For each test start with volume at 0 and have testers ask for
> volume to be adjusted to level they like.
>
> 2) Have the helper randomly set volume each time
>
> 3) (Maybe) use a PC to measure volume - not sure how to do this but I
> do have a cheap microphone and audacity on the PC which should show me
> the volume level - I don't know how accurate this is.
>
> Advice appreciated.
>
> Steve

Steve,

Arny is the "expert" on ABX.
I will defer to his comments on how to stage such a test.

But, you have to ask yourself what are you hoping to determine here?
You will not be able to hear differences that are being masked by distortions
inherent in your playback equipment. That includes distortions from your
amplifier and your speakers.

Put it another way, if you put a virtually "blameless" source into the test
using a system with sufficient distortions of the sort that are detectable by
the ear - and absolute level is not the determinant - then it will sound not
much different than a unit that is reasonably "blameless" in all probability.

It would be a better idea to merely match levels via some sort of simple pink
noise CD source and a cheap Radio Shack SPL meter or just a mic plugged into the
input of any device that has a level indicator - that includes a PC with a
soundcard and some software that shows level, or a tape machine with VU meters -
and simply set the mic in a fixed position and set the levels to be identical
using the pink noise, mark the volume control, and then let ur friend switch for
you, and set it up so that you can not see what he/she is doing.

That's NOT an ABX, but at least you won't know exactly what's going on...

For me personally, it doesn't seem to matter much since I'm not listening for
the things that it seems most people are listening for (simple level diffs for
example), and I do have the ability to level match nicely anyhow...

Bottom line is that if you find yourself wanting to listen to things for a
longer period of time, that is probably the gear/set-up to use. Simple as that.

- -bear

Re: setting up ABX tests at home

Steve wrote:
> I want to set up an ABX test at home on different sources to see if I
> can hear a difference. I am doing this for my own education and fun -
> I don't want to start investing in SPL meters, switches gain
> equalizers of other boxes.

Steve,

As long as you are doing it for fun, the set-ups you have specified
should work. Education is a different matter.

While ABX tests have their proponents, they also have detractors, and
such tests may not educate you about equipment at all. What both
proponents and detractors agree upon is that for short term tests
absolute sound level matching is a must. Many tests have shown that the
louder source is usually preferred.

The very set-up of much ABX testing (which is most often short segments
of music quickly switched), cannot test for what most music lovers are
seeking--long term enjoyment of music listening. A goodly number of
years ago I ABX blind tested some interconnects, and then chose the ones
I preferred. Three months later I realised I was not listening as much
or enjoying it at the level I was previously. I found myself turning the
music down or off. When I went back to my old interconnects my listening
increased to it's previous levels of enjoyment.

Good luck with your testing, I hope it is fun.

Greg

Re: setting up ABX tests at home

"Greg Wormald" <greg.wormald@gmail . com > wrote in message
news:folrst02p34@news1.newsguy . com

> The very set-up of much ABX testing (which is most often
> short segments of music quickly switched), cannot test
> for what most music lovers are seeking--long term
> enjoyment of music listening.

This is a false claim that I've heard on and off for about 30 years, now.

In fact people have been doing long term ABX tests for about 30 years. The
origional ABX Comparator product, had special features to allow tests to
survive power outages, in support of long term tests.

One of the things that long term ABX tests show is that audiophile mythology
about long term testing is just that, audiophile mythology.

> A goodly number of years
> ago I ABX blind tested some interconnects, and then chose
> the ones I preferred. Three months later I realised I was
> not listening as much or enjoying it at the level I was
> previously. I found myself turning the music down or off.
> When I went back to my old interconnects my listening
> increased to it's previous levels of enjoyment.

AFAIK nobody has ever shown that interconnects can be distinguished
sonically using any reliable listening test methodology, unless they were so
bad that they cause non-trival frequency response variations. And, if
interconnects are so bad that they cause non-trivial frequency response
variations, they are by definition, defective.

Re: setting up ABX tests at home

On Sun, 10 Feb 2008 07:53:33 -0800, Arny Krueger wrote
(in article <fon6lt01bbe@news1.newsguy . com >):

> "Greg Wormald" <greg.wormald@gmail . com > wrote in message
> news:folrst02p34@news1.newsguy . com
>
>> The very set-up of much ABX testing (which is most often
>> short segments of music quickly switched), cannot test
>> for what most music lovers are seeking--long term
>> enjoyment of music listening.
>
> This is a false claim that I've heard on and off for about 30 years, now.
>
> In fact people have been doing long term ABX tests for about 30 years. The
> origional ABX Comparator product, had special features to allow tests to
> survive power outages, in support of long term tests.
>
> One of the things that long term ABX tests show is that audiophile mythology
> about long term testing is just that, audiophile mythology.
>
>> A goodly number of years
>> ago I ABX blind tested some interconnects, and then chose
>> the ones I preferred. Three months later I realised I was
>> not listening as much or enjoying it at the level I was
>> previously. I found myself turning the music down or off.
>> When I went back to my old interconnects my listening
>> increased to it's previous levels of enjoyment.
>
> AFAIK nobody has ever shown that interconnects can be distinguished
> sonically using any reliable listening test methodology, unless they were so
> bad that they cause non-trival frequency response variations. And, if
> interconnects are so bad that they cause non-trivial frequency response
> variations, they are by definition, defective.
>

This is correct. At audio frequencies, signal levels, and source impedances,
wire is wire. Now, perhaps at microwave frequencies, the size, composition
and routing of cables makes a difference, but from 20 Hz to 20KHz it matters
not one whit unless you are running extremely long runs (like 30 ft or more)
of coax carrying a line-level signal, then one might experience some small
amount of high-frequency roll-off, but this is not what we're talking about,
here.

Try this. Take a 1-meter length of Radio Shack coax, solder some cheap
tin-plated RCA plugs on each end and use it for one channel of a run from,
say, your CD player to your amplifier (or preamp) and use a 1-meter length of
Nordost Valhalla (at $4000/meter) or any other "high-priced spread" for the
other channel. I DEFY you to hear any difference whatsoever between the two
channels (all else being equal). Cables are snake oil pure and simple. There
is simply no known characteristics of physics, electronics, or music that
would cause any two interconnects to have any sound whatsoever. My rule of
thumb is to buy cables on build quality for reliability and don't spend
another penny above what is necessary to get decent, gas tight connections at
the cable/component interface, and adequate strain relief.

Re: setting up ABX tests at home

Sonnova wrote:
> On Sun, 10 Feb 2008 07:53:33 -0800, Arny Krueger wrote
> (in article <fon6lt01bbe@news1.newsguy . com >):
>
>> "Greg Wormald" <greg.wormald@gmail . com > wrote in message
>> news:folrst02p34@news1.newsguy . com
>>
<snip>
>
> This is correct. At audio frequencies, signal levels, and source impedances,
> wire is wire. Now, perhaps at microwave frequencies, the size, composition
> and routing of cables makes a difference, but from 20 Hz to 20KHz it matters
> not one whit unless you are running extremely long runs (like 30 ft or more)
> of coax carrying a line-level signal, then one might experience some small
> amount of high-frequency roll-off, but this is not what we're talking about,
> here.
>
> Try this. Take a 1-meter length of Radio Shack coax, solder some cheap
> tin-plated RCA plugs on each end and use it for one channel of a run from,
> say, your CD player to your amplifier (or preamp) and use a 1-meter length of
> Nordost Valhalla (at $4000/meter) or any other "high-priced spread" for the
> other channel. I DEFY you to hear any difference whatsoever between the two
> channels (all else being equal). Cables are snake oil pure and simple. There
> is simply no known characteristics of physics, electronics, or music that
> would cause any two interconnects to have any sound whatsoever. My rule of
> thumb is to buy cables on build quality for reliability and don't spend
> another penny above what is necessary to get decent, gas tight connections at
> the cable/component interface, and adequate strain relief.

This is a good example of an invalid test.
Or at least a highly flawed test that is so limiting that the results are
meaningless - and almost always will conform to the expected results.

The amount of acoustical 'cues' available in a mono signal are significantly
lower than from a stereo signal. Put another way, it is much much harder to hear
differences in mono sources than with stereo sources (assuming a stereo set up
that 'properly images'). Therefore a test with left/right channels is doomed to
yield results that don't mean very much about anything.

Stereo is a prerequisite for such tests. Not sufficient, but a prerequisite.

- -bear

Re: setting up ABX tests at home

On Mon, 11 Feb 2008 16:17:48 -0800, bear wrote
(in article <foqojc02tlc@news1.newsguy . com >):

> Sonnova wrote:
>> On Sun, 10 Feb 2008 07:53:33 -0800, Arny Krueger wrote
>> (in article <fon6lt01bbe@news1.newsguy . com >):
>>
>>> "Greg Wormald" <greg.wormald@gmail . com > wrote in message
>>> news:folrst02p34@news1.newsguy . com
>>>
> <snip>
>>
>> This is correct. At audio frequencies, signal levels, and source
>> impedances,
>> wire is wire. Now, perhaps at microwave frequencies, the size, composition
>> and routing of cables makes a difference, but from 20 Hz to 20KHz it
>> matters
>> not one whit unless you are running extremely long runs (like 30 ft or
>> more)
>> of coax carrying a line-level signal, then one might experience some small
>> amount of high-frequency roll-off, but this is not what we're talking
>> about,
>> here.
>>
>> Try this. Take a 1-meter length of Radio Shack coax, solder some cheap
>> tin-plated RCA plugs on each end and use it for one channel of a run from,
>> say, your CD player to your amplifier (or preamp) and use a 1-meter length
>> of
>> Nordost Valhalla (at $4000/meter) or any other "high-priced spread" for the
>> other channel. I DEFY you to hear any difference whatsoever between the two
>> channels (all else being equal). Cables are snake oil pure and simple.
>> There
>> is simply no known characteristics of physics, electronics, or music that
>> would cause any two interconnects to have any sound whatsoever. My rule of
>> thumb is to buy cables on build quality for reliability and don't spend
>> another penny above what is necessary to get decent, gas tight connections
>> at
>> the cable/component interface, and adequate strain relief.
>
> This is a good example of an invalid test.
> Or at least a highly flawed test that is so limiting that the results are
> meaningless - and almost always will conform to the expected results.
>
> The amount of acoustical 'cues' available in a mono signal are significantly
> lower than from a stereo signal. Put another way, it is much much harder to
> hear
> differences in mono sources than with stereo sources (assuming a stereo set
> up
> that 'properly images'). Therefore a test with left/right channels is doomed
> to
> yield results that don't mean very much about anything.
>
> Stereo is a prerequisite for such tests. Not sufficient, but a prerequisite.
>
> _-_-bear

OK. there are other ways to do this test. Use two high-level inputs to your
amplifier/preamp and use a "Y" to feed the signal into a homemade pair and
the Nordost Valhalla simultaneously. Then switch at the amp between the two.
Now you're listening in stereo, but the results will be the same. You won't
hear any differences because they aren't ANY!

Re: setting up ABX tests at home

Arny Krueger wrote:
> "Greg Wormald" <greg.wormald@gmail . com > wrote in message
> news:folrst02p34@news1.newsguy . com
>
>> The very set-up of much ABX testing (which is most often
>> short segments of music quickly switched), cannot test
>> for what most music lovers are seeking--long term
>> enjoyment of music listening.
>
> This is a false claim that I've heard on and off for about 30 years, now.

Well Arny, where is the correlation between ABX tests and subjective enjoyment?
Don't think there is any...?

The ABX is intended and designed to merely yield data about audible differences
between two variables - nothing more.

IF it accomplishes that goal is yet not clear and unproven beyond the specific
test that took place. In other words the results of specific ABX tests can not
be generalized to pertain to every situation. While the results *might* be
useful or of general use, it is not an inherent quality of an "ABX" test.
The reasons - as have been debated here many times - are multiple.

>
> In fact people have been doing long term ABX tests for about 30 years. The
> origional ABX Comparator product, had special features to allow tests to
> survive power outages, in support of long term tests.
>
> One of the things that long term ABX tests show is that audiophile mythology
> about long term testing is just that, audiophile mythology.

No Arny, that is merely your belief and your conclusion.
It is not fully supported by any factual basis.

>
>> A goodly number of years
>> ago I ABX blind tested some interconnects, and then chose
>> the ones I preferred. Three months later I realised I was
>> not listening as much or enjoying it at the level I was
>> previously. I found myself turning the music down or off.
>> When I went back to my old interconnects my listening
>> increased to it's previous levels of enjoyment.
>
> AFAIK nobody has ever shown that interconnects can be distinguished
> sonically using any reliable listening test methodology, unless they were so
> bad that they cause non-trival frequency response variations. And, if
> interconnects are so bad that they cause non-trivial frequency response
> variations, they are by definition, defective.

This would appear to be a true statement.
But it is not.
The reason that it is not true is that the "ABX" tests that have been touted as
providing this information are fraught with unknown variables.
Let me list a few for the readers:
- frequency response of the speakers
- distortion vs. power vs. frequency for the speakers
- polar response of the speakers vs. frequency
- reverberation time vs. frequency of the room
etc. etc. etc....

EVEN WITH this information, I have yet to read a published ABX test that would
permit someone to precisely duplicate the test. Not enough information is provided.

Show me *one* that has the requisite information and controls.

Dr. Earl Geddes' research - and he is a hardcore
academician/scientist/researcher - has shown that absolute values of distortion
do not translate at all to audibility of distortion.

So, the sum total of all this is that ABX is a tool that may or may not yield
information that is useful. Period.

- -bear
>

Re: setting up ABX tests at home

On Mon, 11 Feb 2008 16:17:08 -0800, bear wrote
(in article <foqoi402tkd@news1.newsguy . com >):

> Arny Krueger wrote:
>> "Greg Wormald" <greg.wormald@gmail . com > wrote in message
>> news:folrst02p34@news1.newsguy . com
>>
>>> The very set-up of much ABX testing (which is most often
>>> short segments of music quickly switched), cannot test
>>> for what most music lovers are seeking--long term
>>> enjoyment of music listening.
>>
>> This is a false claim that I've heard on and off for about 30 years, now.
>
> Well Arny, where is the correlation between ABX tests and subjective
> enjoyment?
> Don't think there is any...?
>
> The ABX is intended and designed to merely yield data about audible
> differences
> between two variables - nothing more.
>
> IF it accomplishes that goal is yet not clear and unproven beyond the
> specific
> test that took place. In other words the results of specific ABX tests can
> not
> be generalized to pertain to every situation. While the results *might* be
> useful or of general use, it is not an inherent quality of an "ABX" test.
> The reasons - as have been debated here many times - are multiple.
>
>>
>> In fact people have been doing long term ABX tests for about 30 years. The
>> origional ABX Comparator product, had special features to allow tests to
>> survive power outages, in support of long term tests.
>>
>> One of the things that long term ABX tests show is that audiophile
>> mythology
>> about long term testing is just that, audiophile mythology.
>
> No Arny, that is merely your belief and your conclusion.
> It is not fully supported by any factual basis.
>
>>
>>> A goodly number of years
>>> ago I ABX blind tested some interconnects, and then chose
>>> the ones I preferred. Three months later I realised I was
>>> not listening as much or enjoying it at the level I was
>>> previously. I found myself turning the music down or off.
>>> When I went back to my old interconnects my listening
>>> increased to it's previous levels of enjoyment.
>>
>> AFAIK nobody has ever shown that interconnects can be distinguished
>> sonically using any reliable listening test methodology, unless they were
>> so
>> bad that they cause non-trival frequency response variations. And, if
>> interconnects are so bad that they cause non-trivial frequency response
>> variations, they are by definition, defective.
>
> This would appear to be a true statement.
> But it is not.
> The reason that it is not true is that the "ABX" tests that have been touted
> as
> providing this information are fraught with unknown variables.
> Let me list a few for the readers:
> - frequency response of the speakers

if you are using the SAME speakers for each component under test, the
frequency response of the speakers is a constant, NOT a variable and
therefore is irrelevant. If you are using different speakers for the ABX
test, then you're doing it wrong by introducing more than one variable into
the test.

> - distortion vs. power vs. frequency for the speakers

See above.

> - polar response of the speakers vs. frequency

Again irrelevant because the cables/interconnects are feeding the same set of
speakers.

> - reverberation time vs. frequency of the room

Same room for both components under test, the room becomes irrelevant.

> etc. etc. etc....
>
> EVEN WITH this information, I have yet to read a published ABX test that
> would
> permit someone to precisely duplicate the test. Not enough information is
> provided.

Not needed. All you need is a system and a way to switch between two
different components carrying the same signal at matched levels. This can be
done by a ABX switch box or a third party who either switches or not on
command from the listener(s).
>
> Show me *one* that has the requisite information and controls.

It's really very simple. after matching levels and using the same source
material, merely switch between the two units under test and determine if you
can hear a difference. Listen as long as you like to either or both
contenders and decide whether or not you can tell ANY difference between
them. It's that simple.
>
> Dr. Earl Geddes' research - and he is a hardcore
> academician/scientist/researcher - has shown that absolute values of
> distortion do not translate at all to audibility of distortion.

But that's a different discussion and has nothing whatsoever to do with blind
or ABX testing.

> So, the sum total of all this is that ABX is a tool that may or may not yield

> information that is useful. Period.

Well, ABX/Blind testing can really only tell two things: Is there a
difference in the sound between two components (or interconnects or speaker
cables)? And if there are differences, what are they? It cannot tell which
is better (assuming that there are differences) as that is a totally
subjective call.

Where this type of testing REALLY falls down is where the differences are
subtle (which they often are) and the listener doesn't have the trained
listening acumen to pick-up on those differences. Since there is no way to
eliminate or even pre-screen for this particular variable, the results are
often going to show that there is no difference, when in reality, the
listener(s) just missed them or really cannot hear them. The results never
work the other way where the unsophisticated listener reliably and
statistically hears differences that aren't there. I'm sure that you can see
why that's so.

Re: setting up ABX tests at home

"Sonnova" <sonnova@audiosanatorium . com > wrote in message
news:fotpkn02hkg@news2.newsguy . com

>
> Well, ABX/Blind testing can really only tell two things:
> Is there a difference in the sound between two components
> (or interconnects or speaker cables)? And if there are
> differences, what are they? It cannot tell which is
> better (assuming that there are differences) as that is a
> totally subjective call.

Agreed.

However, if someone can't reliably detect a difference, how can there
reasonably be a preference based on sound quality? Having a preference
presumes the existence of a difference.

> Where this type of testing REALLY falls down is where the
> differences are subtle (which they often are) and the
> listener doesn't have the trained listening acumen to
> pick-up on those differences.

This problem exists for any listening test. The only reason why it is more
apparent in DBTs is that DBTs clearly detect listeners who can't reliably
detect differences for whatever reason.

> Since there is no way to
> eliminate or even pre-screen for this particular
> variable,

Actually, there are many means for screening out listeners who aren't
adequately trained. Describing them all goes beyond the scope of a RAHE
post.

Re: setting up ABX tests at home

On Wed, 13 Feb 2008 16:33:19 -0800, Arny Krueger wrote
(in article <fp028f01mvd@news4.newsguy . com >):

> "Sonnova" <sonnova@audiosanatorium . com > wrote in message
> news:fotpkn02hkg@news2.newsguy . com
>
>>
>> Well, ABX/Blind testing can really only tell two things:
>> Is there a difference in the sound between two components
>> (or interconnects or speaker cables)? And if there are
>> differences, what are they? It cannot tell which is
>> better (assuming that there are differences) as that is a
>> totally subjective call.
>
> Agreed.
>
> However, if someone can't reliably detect a difference, how can there
> reasonably be a preference based on sound quality? Having a preference
> presumes the existence of a difference.

Agreed. If someone is an unsophisticated enough of a listener to be unable to
discern ANY difference, then he/she likely has no preference, or at least has
no preference at THAT level of minutia.

>> Where this type of testing REALLY falls down is where the
>> differences are subtle (which they often are) and the
>> listener doesn't have the trained listening acumen to
>> pick-up on those differences.
>
> This problem exists for any listening test. The only reason why it is more
> apparent in DBTs is that DBTs clearly detect listeners who can't reliably
> detect differences for whatever reason.

Agreed.

>> Since there is no way to
>> eliminate or even pre-screen for this particular
>> variable,
>
> Actually, there are many means for screening out listeners who aren't
> adequately trained. Describing them all goes beyond the scope of a RAHE
> post.

Well, I meant that there is no practical way without extensive procedures
that most people wouldn't be willing to go through - on either end of the
test.

Re: setting up ABX tests at home

Sonnova wrote:
> On Mon, 11 Feb 2008 16:17:08 -0800, bear wrote
> (in article <foqoi402tkd@news1.newsguy . com >):
>
>> Arny Krueger wrote:
>>> "Greg Wormald" <greg.wormald@gmail . com > wrote in message
>>> news:folrst02p34@news1.newsguy . com
>>>
>>>> The very set-up of much ABX testing (which is most often
>>>> short segments of music quickly switched), cannot test
>>>> for what most music lovers are seeking--long term
>>>> enjoyment of music listening.
>>> This is a false claim that I've heard on and off for about 30 years, now.
>> Well Arny, where is the correlation between ABX tests and subjective
>>

<snip>

> onnects are so bad that they cause non-trivial frequency response
>>> variations, they are by definition, defective.
>> This would appear to be a true statement.
>> But it is not.
>> The reason that it is not true is that the "ABX" tests that have been touted
>> as
>> providing this information are fraught with unknown variables.
>> Let me list a few for the readers:
>> - frequency response of the speakers
>
> if you are using the SAME speakers for each component under test, the
> frequency response of the speakers is a constant, NOT a variable and
> therefore is irrelevant. If you are using different speakers for the ABX
> test, then you're doing it wrong by introducing more than one variable into
> the test.

You are simply not comprehending the significance of masking due to
distortion(s) nor the effect of cascaded distortions.

Put it another way, IF the distortions present are of a particular type or class
then you can put anything you like into the signal chain of lower or nil
distortion and most likely not be able to identify any change. Since you have no
way to determine the significance or type/class of distortions in your system,
you don't know anything about the results of an ABX test other than the results
being SPECIFIC to the test you performed.

>
>> - distortion vs. power vs. frequency for the speakers
>
> See above.
>
>> - polar response of the speakers vs. frequency
>
> Again irrelevant because the cables/interconnects are feeding the same set of
> speakers.
>
>> - reverberation time vs. frequency of the room
>
> Same room for both components under test, the room becomes irrelevant.

That is simply wrong and incorrect IF you wish to generalize the results beyond
the specific test.

Let's do a simple mental excercise on this, ok?
Put the speakers into a relatively small room made of ceramic tile, do the test
there. Are those results meaningful? Yes? No?

I assume the answer will be *no*.
The point is that the room does matter - the question is to WHAT DEGREE. It is
not irrelevant it is a non-zero factor. If it is not controlled and known, then
it is a variable whose effect is UNKNOWN. Therefore the validity of the tests is
compromised and can be called into question.

Obviously, let's not push the thing into absurdity - at some point things can
not be known - but the present crop of ABX tests that I know of don't take into
account relatively simple, basic things that CAN be known.

>
>> etc. etc. etc....
>>
>> EVEN WITH this information, I have yet to read a published ABX test that
>> would
>> permit someone to precisely duplicate the test. Not enough information is
>> provided.
>
> Not needed. All you need is a system and a way to switch between two
> different components carrying the same signal at matched levels. This can be
> done by a ABX switch box or a third party who either switches or not on
> command from the listener(s).

If you wish to make this assertion, so be it.
It is not valid science, nor does it yield particularly useful results except by
serendipitous result.

>> Show me *one* that has the requisite information and controls.
>
> It's really very simple. after matching levels and using the same source
> material, merely switch between the two units under test and determine if you
> can hear a difference. Listen as long as you like to either or both
> contenders and decide whether or not you can tell ANY difference between
> them. It's that simple.

NOT that simple. Sorry. Wrong.
For all the reasons stated.
That test is ONLY valid in the system under test. Period.

>> Dr. Earl Geddes' research - and he is a hardcore
>> academician/scientist/researcher - has shown that absolute values of
>> distortion do not translate at all to audibility of distortion.
>
> But that's a different discussion and has nothing whatsoever to do with blind
> or ABX testing.

WRONG. It has *everything* to do with ABX and *all other listening tests*.
Read it yourself.
Report back.
No reason to be ignorant of this new research!!

>
>> So, the sum total of all this is that ABX is a tool that may or may not yield
>
>> information that is useful. Period.
>
> Well, ABX/Blind testing can really only tell two things: Is there a
> difference in the sound between two components (or interconnects or speaker
> cables)? And if there are differences, what are they? It cannot tell which
> is better (assuming that there are differences) as that is a totally
> subjective call.

That is not being discussed.

>
> Where this type of testing REALLY falls down is where the differences are
> subtle (which they often are) and the listener doesn't have the trained
> listening acumen to pick-up on those differences. Since there is no way to
> eliminate or even pre-screen for this particular variable, the results are
> often going to show that there is no difference, when in reality, the
> listener(s) just missed them or really cannot hear them. The results never
> work the other way where the unsophisticated listener reliably and
> statistically hears differences that aren't there. I'm sure that you can see
> why that's so.

Unfortunately, that is NOT what research has shown at all.

You keep insisting on "differences that are not there."
That is an assertion that may or may not correlate with tests that may or may
not be effective at testing what they purport to be testing!!

What you want to say is that *you believe* that the majority of differences
reported by non-ABX test listeners are not real differences. That is your
belief, which you are entitled to. There are no tests that adequately support
such a point of view. Again, I urge you to actually read at least the abstract
of Dr. Geddes work to understand WHY I keep saying this sort of thing!! : )

- -bear