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Audio by Van Alstine ABX Comparator Review, Part 1: Audio Store & Wiring

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It takes an audio store

Full use of the Audio By Van Alstine ABX Comparator takes a pile of components and cables! Many will consider the effort outside their means or interest, as it requires either a minor or major duplication of gear. While a person can conduct a comparison of just one set of cables, say interconnects, or one component, ABX testing proves itself a powerful method as one compares entire systems.

The wiring necessary to pull off this stunt is considerable. The demand is not great when making one of the most basic comparisons, say between two pairs of speakers. In that case one needs two pair of identical interconnects (one pair for the source’s L/R output into the ABX Comparator, and one pair for the Comparator’s L/R output of the source to the amp) and three pairs of speaker cables, two of them identical. The first set of speaker cables, preferably with Banana connectors, returns the amp’s high level signal to the Comparator, and from there it is switched to either speaker A or B. This assumes the speakers used are single wired! If they are bi-wired then two sets of jumpers, likely native to the speakers, are needed, or four sets of identical speaker cables are needed.

If a second source and amp were to be added, two more pairs of identical interconnects are needed, as well as one additional set of speaker cables. This would put the total number of cable sets required at: 4 sets of identical interconnects, and four sets of identical speaker cables (assuming single wired speakers). It quickly becomes apparent that one does not go into exploration with an AVA ABX Comparator unless they have a lot of multiples of wires lying around, or are intent on securing them. My most “busy” system comparison used a single digital source, my Mac Mini, and either two DACs routed through a single preamp, or a single DAC routed through two preamps. The Comparator can only accept two “sources”, and does not handle digital signals, so variations of DAC and preamp must be addressed so as to ensure an analogue signal is sent to the Comparator. In addition, I compared two amps and two sets of speakers, for a total of six discrete elements, all available to compare in isolation, combination or entirely. One of the powerful inducements to using the ABX Comparator is the ability to specify precisely which components or speakers you wish to combine and compare! As a system builder I found this immensely enjoyable.

The ABX Comparator allows for comparison of a “lopsided” system with two very different sources, such as: CD player (Source A) compared to file playback with a DAC (Source B). Though some might not consider this a “fair” comparison, the ABX Comparator can show the owner which they might prefer in a truly unbiased comparison. The value of lopsided testing would be to see whether a switch in technology could confer a distinct advantage. For the most part I stayed with comparing preamps to preamps, DACs to DACs, etc.

The speaker cables running from the amps to the ABX Comparator box were “shorties”, only three feet long. As the Comparator rested right next to the amps, not up on a shelf, the speaker cables going from the amps returning to the Comparator to be switched were not long. Eight-foot long speaker cables exited the ABX Comparator to the speakers. There is no facility to conveniently compare subwoofers, but one can be added to play along with the speakers being compared, and this is critically important if one wishes to see how well a pairing of a particular subwoofer and speaker performs.


How I did the wiring

I knew it would be all but impossible to acquire many sets of cables from a manufacturer for the ABX testing, so I cheated. I used two brands of cables, some on hand from previous reviews and some borrowed from Chris VenHaus at VH Audio. Critically, despite the use of more than one brand, all signal paths were identical, that is, whatever model of cable was used at a particular point in the wiring schematic in system A, the same cable was used in the same location in system B. In this way consistency was attained, as whatever was played through the one system the same wiring was used in the other, even down to the power cables.

As it was, I held my breath when I turned the unit on after making 30 connections for comparison of six components. Had I used a third pair of speakers there would have been another 4 connections required. This on a piece of component real estate no larger than a backside of a CD player! Visual confirmation of connections was difficult and sometimes nearly impossible. Forget putting the ABX Comparator back against, or in, any kind of cabinet or wall, as the risk of a miswiring is too high. All it takes is one flub and an amp could be blown up.

My understanding is that AVA has now put safety features in the ABX Comparator to prevent such a disaster, namely the amp and speaker switching now switches both the hot and ground side; there is no longer a common ground between speaker level terminals. This allows safe testing of bridge mode amplifiers and protects from blowing out an amp channel due to inadvertently reversed speaker connections. Now, all that will happen is the speaker operating out of phase. But, I was doing a high wire act without a net! I checked connections many times prior to flipping the power switch! Even at that, the diagrams supplied with the Manual were not perfectly clear, technically correct, but abbreviated. Not every connection is shown but only the primary designation of the connection. For instance, rather than show all eight speaker leads going to Speakers A and Speakers B two lines show the direction of the connection from the ABX Comparator to the speakers. This is one reason reading the Owner’s Manual and wiring up an ABX Comparator can be daunting.

The diagram of a system utilizing a single source, two amps and two speakers was confusing, as every component was presented as connected by a single arrowed directional line with the designation “RCA” or “BANANA”. There would be a minimum of 14 connections in that system, but only 7 were shown. The Manual does discuss Left and Right connections, but some users might become befuddled at the mental disconnect between the diagram and instructions.

People who have made connections to the rear and front of components will pause momentarily until they comprehend that the diagram does not represent connections on both sides of the ABX Comparator; it is impossible, for there are no connections on the face of the unit. The diagram shows only the backside, and there are so many necessary connections that components have been placed on both sides of the ABX Comparator in the diagram to relive visual congestion. Still, there are some discrepancies between the diagrams and the Comparator itself. On the diagram two preamps are shown entering the Comparator at opposite ends of the unit, when they both actually enter next to each other on one end. The notation for the “B AMP” output leads to the ABX Comparator where it is named “A AMP In Banana”, which seems incorrect given just above resides the “A AMP” Out and In connections on the ABX Comparator.

For such reasons if you are squeamish about wiring you do not want to set this component up, but will want to solicit the help of a very experienced audiophile who can work their way through diagrams, and perhaps even give AVA a call.

The Manual calls for only Banana connections for speakers, the reason being that the sets of posts are so closely spaced that many types of spades and hefty cables will simply not fit. Heed that instruction, or be immensely frustrated. For this review, I used some ultra-pure copper twisted pair cables from Chris VenHaus at HV Audio for both the high level leads for the amps to return to the ABX Comparator and the speaker cables.

There was one glitch discovered in the operation of the AVA ABX Comparator. Four times, more than simply an anomaly, when I pushed the button on the Sony remote corresponding to the function “Input”, to summon system B, the source, even if delineated as source A, would also switch from A to B. The result was silence if there was no B source being used. I did not notice this happening during the ABX testing trials, but it should be explored further by Van Alstine.

If all this has not turned you off from trying the ABX Comparator, perhaps you are a glutton for punishment, or a born System Builder like myself. The thought of wiring all this was daunting (Note, I have said this a few times, so gung-ho know-it-all types beware!), but the reward of an honest blind test to assess the systems and my ears was too much to put me off from the task! It took quite some time to finalize the wiring, and because it was late that evening I waited until the next day to recheck the connections with a fresh mind before turning it all on. Nothing blew up! So, this article proceeds to the testing and results!


Next: Audio by Van Alstine ABX Comparator,

Part 2: Trials,

Part 3: New Twists & Conclusion

4 Responses to Audio by Van Alstine ABX Comparator Review, Part 1: Audio Store & Wiring

  1. Charlie mathews says:

    I have forwarded this series of articles to some of my friends who do regular testing/listening of differnt audio components. Over all I want to thank Doug for all his work! It was a great effort. NO buts!
    I will say this that in the past when some of my colleagues and I were conducting blind back and forth champagne tasting tests between some very low cost sparkling wines (the kind you find in 7/11’s) and very EXPENSIVE French champagnes many novices were not able to discern or detect a difference among the wines tasted. WE could not figure that out….not necessarily a parallel with Doug’s finding but some similarities. All in all Doug’s article was way cool because it has got me thinking about other similar human phenomena.
    Best to you guys


  2. Anonymous says:

    The problem I have with performing ABX comparisons of audio equipment is that it’s impossible to perform without adding additional equipment which is not normally present when we connect our audio system. Any additional equipment presents potential changes to the system mitigating any actual differences in equipment we are trying to compare. Look inside this ABX switch box, I see a lot of capacitors, crappy RCA connectors (all RCA connectors suck, some just suck less than another), integrated circuits, diodes, a power supply, resistors, etc. So that ABX switch box, WITH additional cables, is going to filter the audio signal and since it’s one more piece of equipment not normally present, then it’s just going to make both sound more similar to each other.

    Nice try, but I’m not going to suggest that people think that this ABX switch box with additional cables is NOT going to be a factor in what we hear.

    Unfortunately, there is no definitive testing mythology for ABX testing and any test performed is only that test that’s performed with the people used in the test and that’s all any test really is.

    I would suggest that people download the Harmon How To Listen app first and pass all of the tests before they make any definitive statements about something having no difference.

    Let’s first focus on one’s listening skill set first.

    • Gee anonymous, some inaccurate comments there. First of all, the capacitors, integrated circuits, diodes and resistors are not in the signal path at all. Second, the RCA jacks are not crappy. Yes, they are not $100 each ones, but if we used those the cost of the unit would double.

      Note that Doug was able to reliably detect differences between different brands of premium cables he used so our ABX box can’t be doing much masking.

      The ABX box simply reveals truths about equipment differences that make some audiophiles uncomfortable.

  3. “Anonymous”
    God’s Peace to you,

    According to your analysis, the addition of any component containing capacitors, RCA connectors, integrated circuits, diodes power supplies or resistors should make all systems sound more similar to each other. That is not my finding.

    You state, “There is no definitive testing mythology [sic], but I believe you meant methodology. If you wish to not accept my findings because you weren’t in the test, so be it. It is relatively easy to dismiss findings when one is not the subject of the testing, if that’s the criteria chosen to believe the results.

    Regarding focusing on one’s listening skills, there are no special listening skills required to hear a difference in an ABX test. There either exists a difference, or there does not. If one cannot tell, then one will fail the ABX testing.

    I’m not interested in further discussion, when you conclude, “… about something having no difference.”
    Unless one has done ABX, I don’t think one is in a position to make such a declarative statement.

    Douglas Schroeder

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