[avahifi]

For you DBT fans, rejoice!  Audio by Van Alstine has just completed our very own ABX test box.  Originally, we just wanted something to allow us to compare circuit ideas in house, but as word as got out about it, the requirements have grown and thus so have the capabilities.

The box allows you to connect two preamplifiers, two power amplifiers, three speaker system pairs, and a subwoofer (with both in and out connections).  You can mix and match any pair of components and speakers (with or without subwoofers), and control the selections from the supplied remote control.

Output levels can be matched exactly and easily with the use of a simple digital meter reading AC volts.  You can either set the level of both systems under test by matching output levels with the meter, or simpler yet, simply adjust to null the differences with the meter.

Then you can use the setup simply to switch preamps, amplifiers, and or speakers and keep track of what you are listening to, or - - - you can enter the test mode.

To do this you would want to set up one component in each signal path that is different.  System A might consist of preamp A, power amp A, and Speaker set A for example.  Then set up system B as preamp A, power amp B, and Speaker set A.  This case would allow comparison of power amps only.  Match levels exactly with the meter and you are ready for true DBT time.

Enter the test mode and all the indicator lamps are turned off, the starting point is randomized the dispaly lights up saying "Test 1".  Listen away, make notes, and when you want to, press the test button again.  This will then switch to Test 2 and the power amp under test will switch to the other power amp, or --  maybe not.  This depends upon the random number generator making life difficult for you.  Listen again, make notes again, and press test again and switch to Test 3. Repeat for the entire 8 test program session.  Each test either switches or does not switch the component you are listening too.  At the end of 8 tests, you can keep going, repeating the cycles as long as you want.  Or you can then switch out of the test mode and the displays will light up again.  Now going through the 8 cycles once more will tell you exactly what you had been listening too.

This allows you to take all of the huge audio sugar pills out of the listening process and provides some interesting and often humbling results.

There are absolutely no active components in the ABX box, nothing to "mask" or "ruin" the system sound.  What you have set up is exactly what you are listening too.  With identical components in the test chains, you can use the ABX box to listen to interconnects, speaker cables, or even high end fuses too.  Even more fun.

The tests can be absolutely stress free.  Listen as long as you like to one test sequence yourself.  If it takes half a day to really "learn" what a given component sounds like, take that long if you desire. Its just your time.

We think that this really transparent ABX box might be useful to a variety of listeners.  Audio clubs, speaker builders, electronic component builders, audio stores, even interested audiophiles.  We don't have a price for the unit yet, probably under $2000.

The ABX box even has a computer connection to allow future programming updates and revisions.

So - - - who is interested?  If not interested, why?

Regards,

Frank Van Alstine

[jtwrace]

So - - - who is interested? 

I posted in your thread here http://www.audiocircle.com/index.php?topic=105685.0 but it went unanswered. 

probably under $2000.

[Devil Doc]

A device like this could pay for itself in a very short period of time. I don't suppose it would be constructive to list the folks that won't be buying one.

Doc

[jtwrace]

A device like this could pay for itself in a very short period of time.

Doc

I think a rental program on it would be ideal.

[avahifi]

I will have photos in a couple of weeks when the first production unit is finished.  We just got the first run of PC cards back from the fabricator yesterday.  My engineer is populating the board right and then the big job of all the internal connections to all the jacks.

There are 14 RCA jacks; source in, two sets of source out, two sets of preamp in, two sets of preamp out.  There are 10 sets of dual 5-way binding posts, four sets of from amplifiers, six sets to speakers, two sets of to subwoofers, two sets of from subwoofers. Plus IEC power jack, fuse, and ground lift switch.

The remote control uses standard Sony codes so if you loose or step on the remote, you can buy a replacement cheep.

Front panel display shows levels of component selected (to 0.1dB steps) or number of test sequence.

Asking why not interested?  I just want to hear the lame excuses again although cost will be an issue to many unfortunately.  The unit takes lots of hand made work as at this point as tooling a specific chassis would be way too expensive.  Its done with a standard chassis box (17" x 3.5" x 10" deep).

Frank

[planet10]

There are absolutely no active components in the ABX box, nothing to "mask" or "ruin" the system sound.  What you have set up is exactly what you are listening too.

But there are switches, connectors, internal woring and PCBs? Not to mention extra interconnection cables.A picture of the inside, and some description of these critical components.

In Kunchurs landmark paper on "time delay " detection" the most intersting part was the legths he has to go to make sure that the ABX box did not confound the results.

dave

[srb]

Unless you're using TWO identical pairs of speaker cables or interconnects for the From and To connections, I see little value in the comparison of cables if they are running in series with a different common cable.

Steve

[Otis]

.

[BobRex]

Not interested.  Why????  Because I really don't give a rat's patootie if I can hear the difference between my amp and anything else.

Frank, you make tube, hybrid, and SS amplifiers.  Do they all sound the same within their performance envelope?  If so, then why make all three?  If one sounds better than the other(s) why are you making the others?

[avahifi]

Interconnect cable testing requires two identical systems.  All cables and speaker wires identical except for pair under test.  If testing interconnects, you only need one amp to test cables between two preamp and the power amp.  Speaker wires, you still only need one amp too.  Since there are separate cable connections from source to preamps, then from preamps to power amps, and then from power amps to speakers, a single cable under test can be substituted anywhere.

Testing results here.  Instant A-B short term testing yields very unpredictable results.  More consistent results come from reasonably long term evaluations spread over at least an hour for each unit and several music samples. However, eliminating "feelings" also eliminates listening prejudices and produces worthwhile circuit and product evaluations.  When you are considering new equipment you are paying a whole bunch for "feelings". 

Regards,

Frank

[avahifi]

Of course if you are blessed with ESP, then of course you need no ABX box or its ilk.  You already know what is great or bad without needing to listen at all.

I wish I had this or it could be taught to me.  Pray tell how. 

Frank

[Freo-1]

DBT may be based on science, but, it is clearly an incomplete science at best.  Contrary to what supporters of DBT believe, the entering arguments for DBT testing are limited and incomplete, and as such are not valid in an absolute sense.  Speaker load and room interaction play much more into comparisons that switching between two amps connected to a box that will do nothing to help but potentially degrade the sound. 
 
For an amp manufacturer to use one makes some sense, as it does provide a reasonable level of comparison between a two or more designs.  However, there are way too many shortfalls with using a DBT box to compare two different amps OVERALL performance.  A power cube will actually tell one more about the amps performance characteristics. 
 
The only method to judge a given amp is to actually use them in your own system for a period of time listening to a lot of different types of music.  Only by this method can one really tell what differences there are between amps.  For some speakers of higher efficiency and present a benign load, it may difficult to pick up differences.  For other speakers that present more of a load challenge, differences will be much more easily heard, especially at moderate or louder volumes.  This is one of the major reasons why a Class A amp that is rated at 30 to 50 watts RMS at 8 ohms can and often does sound better than a more modest amp that is rated at 75 to 100 watts RMS at 8 ohms.

[Devil Doc]

DBT may be based on science, but, it is clearly an incomplete science at best.  .

Well, I cut out the BS and double talk. That statement is simply not true.

Doc

[Freo-1]

Well, I cut out the BS and double talk. That statement is simply not true.

Doc

 
Yes it is.  You asserting otherwise is meaningless. (or BS, if you prefer).
 
If you understand science as claimed, you should understand that there are limitations to scope of DBT.  To argue that all the bases are covered with DBT is naive.

[*Scotty*]

From mgalusha Welcome to the lab. See link http://www.audiocircle.com/index.php?topic=71571.0

There are a few rules in addition to the standard Audio Circle Rules and posting guidelines. I am going to continue the policy of keeping The Lab a DBT discussion free zone for exactly the same reasons as one of the previous facilitators, those threads always end up hostile and I have limited time for facilitating and would much prefer not to spend it bashing heads from threads that were doomed from the beginning.

 If this ABX Tester is offered for sale by AVA then we have a potential problem with what amounts to a promotional post in the Lab Circle by a vendor that might be better placed within the Audio by Van Alstine Circle in the form of a sticky.
Scotty

[Devil Doc]

I'm beginning to understand! These arguments are fruitless. If folks want to carry water for the more unscrupulous in the high end industry, why should I care. It worse than arguing politics. I'm done. Hear what you think you hear. Waste your money. After all, it's yours to burn.

Doc

[Early B.]

Forget about DBT. To me, the real value of the ABX test box is not to prove anything to anyone except for the owner or renter of the test box. Imagine having an ABX test box and you want to see how your tube amp compares to your friend's SS amp because you're considering purchasing the same amp. You can use the ABX test box to determine if you prefer the sound of one amp over the other. And being able to change amps on the fly would be wonderful. The test box would also be very useful for borrowing items from your local high end audio store to test the potential significance of an "upgrade" before you buy it. I've been looking for a device like this for 15 years. Price notwithstanding, if you can think of a better way to make such a comparison, I'd like to hear it.

[Freo-1]

Here is a link to discussions on DBT:
 
http://www.avsforum.com/t/1154734/why-blind-listening-tests-are-flawed-per-robert-harley
 
 

[Freo-1]

Let’s not confuse the snake oil issues from DBT.  No one is supporting wasting cash on questionable science.  However, claiming for example, that a mid-fi receiver will sound like a Pass Labs Class A amp (as some DBT folks claim) is naive.  Again, the speakers, speaker load, source equipment, and room interactions all play a part in the playback.  DBT only ever addresses a small subset of the entering arguments, and depending on those, one may or may not hear a difference.
 
I know for me, I used to think the Class A amp subjective improvements were not true.  It was not until I actually had one in my system for a period of time did I notice just how different recordings I thought I knew sounded different (better).  As each component of the system was improved, the Class A amp better highlighted the improved performance from the component upgrade.  Adding a Servo subwoofer REALLY provided a significant upgrade.

[Devil Doc]

Come on, get with the times. Even Peter Aczel finally admitted not all amps sound the same.

Doc