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Audio by Van Alstine ABX Comparator Review, Part 2: Trials

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Read Part 1: Audio Store & Wiring

Read Part 3: New Twists & Conclusion

The components and speakers used

I completed the listening sessions for ABX testing by building four distinct systems, using two at a time and separating two large blocks of listening sessions over several days by a few weeks in between. The first pairing of systems was decidedly low end, with economical speakers and cables. I wished to determine if the use of some inexpensive gear would ruin the potential to discern between systems. For instance, would less expensive speakers have enough of their own sonic signature for me to pick them out blindly? Here in its entirety are the elements of the initial test systems being compared. As you can see, there is a combination of elegant and economical gear, in which you should note the nearly identical amps:

Mac Mini running iTunes

Clarity Cable Organic USB

Exasound e22 DAC

Clarity Cable Organic RCA Interconnects

AVA ABX Comparator

 

(System A)

TEO Audio Liquid Pre; Wells Audio Innamorata Signature; Insignia 6” two-way

Coaxial speakers

 

(System B)

Cambridge Audio Azur 840E Preamp; Wells Audio Innamorata; Boston Acoustics

CR-7 bookshelf speakers

 

For these systems the bulk of the wiring was inexpensive Radio Shack 16 gauge audio cable, and both signal paths between systems were wired identically, including the power cords. The two versions of Innamorata amps offered an opportunity to compare an upgraded amp for assessment of the upgrade’s efficacy.

I paid quite a bit of attention to the placement of the speakers for systems A and B, being careful to have them equidistant from the listening chair, and placing them as follows:

(Left) A/B and (Right) A/B. The speakers were very close to each other, about 1-inch apart, and the 1-inch gap between them was in alignment with each respective ear so as to make it more difficult to discern from the soundstage and center image which speaker was playing. I felt the pairing of Left and Right of the A and B speakers was a more challenging placement than if I had placed one pair outside and the other inside, like so: (Left) A/B and (Right) B/A. In my listening I was not able to detect a shift in the soundstage and center image, that could give away which speaker was playing, thus I considered the placement a success for the trials.

Initially I used only system A listed above to casually switch sighted between the preamps and speakers to gain familiarity with the ABX and the sonic signature of each system. I ran through some very familiar tracks such as Marc Cohn’s “True Companion”, Steve Oliver’s “Bend or Break” recorded live, Christina Aguilera’s “Walk Away”, and Simply Red’s “Holding Back the Years”. I spent time flipping between the preamps, amps and speakers. In a premonition of sorts, I found the amps to sound all but indistinguishable. At the time I thought perhaps other influences were at work, and I knew I would return to a proper ABX testing of amps, so I moved on.

The system which caught my ear, that is, seemed most high-end to me, was system B, and I initially determined that the speakers were the most critical in that conclusion. When I compared preamps, with only one speaker the TEO Liquid Pre seemed much more luxurious, and yet when the systems were compared in entirety the Cambridge Audio pairing with the Boston speakers was the favorite. This is not to suggest that a preamp is negligible, for I also swapped systems to create a “most favorable” and “least favorable” pairing by reversing the preamps, and in that case the TEO Liquid Pre with the Boston speakers was even more convincingly upscale. I was informally getting to do real time matching of gear and selecting the combos I felt were most worthy. This alone is a powerful use of the ABX switch, and an audiophile who is contemplating spending a lot of money on a source, preamp, amp or speakers could resolve burning questions in their mind about the worthiness of an upgrade.

 

Blind testing

Then it came time (Finally!) to test my ears by shutting off the front display, putting the ABX into Test Mode. Since the Owner’s Manual refers to each incident in blind testing mode as a “test”, I will retain that terminology, and will apply the term “Trial” to indicate an event of 8 tests preprogrammed into the ABX. I did not see in the Manual a means of altering the frequency of tests when in blind testing mode. Here is where things began to get interesting! I say interesting, but truthfully, they became a bit scary, too. I obtained some results which I was quite confident would turn out the way they did, but in a few situations I was shocked by the results.

I first did a sighted dry run, stepping through trials 1-8 while seeing the indication on the display of which system was playing. I perked up to see that Trial 1 was system A, Trials 2-7 were system B, and Trial 8 system A. I had read in the Manual that occasionally the random generating switching might string along several tests without changing, and it had happened in the walk through!

Sensing that I had a handle on the characteristics of the two systems, I jumped into Blind Testing mode and put on Steve Oliver’s “Bend or Break,” slowly working my way through the 8 tests and writing down my guess as to which system was playing. The results? I was correct 7 of 8 times! The error came in the first test, which I selected system A, but knew instantly when I proceeded to test 2 that I had erred; the fuller, richer sound went away which meant I had initially been hearing system B.

This mistake is what I came to think of as an Orientation Error, in which the first selection in a blind test comparing two systems is essentially a true guess. As there is no immediate context to compare the sound and gain assurance of the guess, there is a 50/50 chance of being correct. I assumed, then, that if one was not correct initially and the random program continued to select the same system, one could be wrong as many as three or four times until a test with a switch of systems did occur. That meant the Orientation Error could conceivably result in blowing the entire Trial of 8 tests by missing on the first three or four. This would not definitively demonstrate an inability to discern between the sounds of level-matched systems, but only that one cannot have certainty in selecting between them until an actual switch of systems occurs.

I found my hypothesis to be borne out over time, as whenever I misjudged the initial test and in test 2 or 3 the systems were switched, I was quickly able to get “back on track” and complete the testing with nearly perfect accuracy. However, the second Trial taught me some additional lessons! Feeling confident, I decided to switch speakers and place a time limit of 30 seconds on my tests. System A now consisted of the Liquid Pre/Innamorata Signature/Insignia speakers, and System B consisted of Cambridge pre/Innamorata/Boston speakers.

Feeling buoyed by my initial success, I thought I would “predict” my score! The first Trial seemed such a cakewalk that I thought I would offer a prognostication of the results. In this instance I did not “reacquaint” myself with the sound of the systems A and B; I just changed them and after testing for level matching, went to the blind testing. In blind test mode I again went through the same piece of music and watched the clock to switch tests.

The results were horrific, and I knew it! My notes regarding the outcome were prophetic, “I predict a mess, horrid score. Why? Systems are more closely matched tonally and detail.” Boy, was I right, as I scored zero; I got all 8 of the tests wrong. When returning the functionality of the front display to step again through the 8 tests, I knew it was a disaster when I saw the first test showed system B. I had confused the sonic properties of system A with system B. I had perfect consistency in selecting the wrong systems, because I had misjudged their sound.

In a way this was bad, but in another way this was good. It was bad because it showed how easily we could ascribe to a rig an inaccurate set of sonic characteristics. However, when in the actual testing, I was able to discern consistently when a switch between the systems occurred. I knew that I would have to pay far more attention to the nuances of a system or component to score well, but I also knew that hearing the changes between systems was not as impossible as some suggest.

5 Responses to Audio by Van Alstine ABX Comparator Review, Part 2: Trials


  1. Dan Kuechle says:

    Here is a list of the latest changes / additions to the ABX box:

    1) As mentioned in the article, the common ground requirement between speaker level components has been be removed, thus allowing bridged amp testing and no damage from an inadvertent reversed speaker connection.
    2) At any time now, during blind test, system A or system B can be selected (as well as going back to system X). This allows the listener, at any time, to reference either system and then go back to the unknown system under evaluation.
    3) In blind test mode it has always been possible to run thru the 8 tests as many times as you want. moving from test 8 to test 1 in the “up” direction and from test 1 to test 8 in the “down” direction.

    Dan Kuechle, designer – AVA ABX Box

  2. Anonymous says:

    I wouldn’t use a additional box and cables to compare audio equipment, it just adds more to the system that’s not required or normal to have and all it’s going to do is mitigate any differences there are between the equipment being compared.

  3. Werd says:

    Hello
    While in possession of the ABX comparator did you leave the comparator your main listening system?
    That is not in use as comparator but running, inserted and hooked up in your system?

  4. Dan,
    God’s Joy,
    Thank you for the updates to the unit!

    “Anonymous”
    Unless you have perfect hearing, which I highly doubt, and perfect recall for that matter, then the additional equipment IS necessary to ascertain whether one is able to pick out gear or systems in a blind test. Also, unless one has definitive proof that all such equipment actually does mitigate any differences, then your assertion is conjecture.

    Blessings,
    Douglas Schroeder

  5. Werd,
    The Joy of the Lord to you,

    No, I removed the ABX when building systems for other reviewing purposes.

    Blessings,
    Douglas Schroeder

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