Addendum, April 20, 2015: In a conversation with Frank just before this article was sent off, I discussed with him my findings regarding the ABX Comparator and amps. As I had reached my conclusions in the article and he had not seen the finished article, I have not gone back to edit the article, but instead add the discussion here.
Frank gave insight about the uniformity of amplifier sound, noting that in his shop he uses two very different speakers, through which differences in amps can be heard. However, he noted that the differences are very subtle, and the speakers he uses are quite different; Philharmonic Audio’s Philharmonic 3 and Janzen zA2.1 electrostatic speakers. Recall that I commented that it would be expected for different technology and/or sized speakers to sound obviously different. This would shed light on my findings, that with nearly identical speakers amps could not be distinguished, but with Frank’s obviously different speakers they could...
The very first prototype had a built in tone generator plus dummy load plus test points for a digital multimeter. It only worked properly when 1 set of speakers was used. Once different efficiency speakers were involved, it was pretty much worthless as there was no way to measure the actual acoustical output from the speakers, and even if we had something it would be next to impossible to accurately account for left / right. Since this approach didn't solve the problem for half the setups the ABX box could be used in, we decided to scrap the idea. Good riddance.
Dan
By the way danielgk is our electrical engineer and he does great work for us.
Frank
what is one of these babies gonna cost?
Sorry if this has been answered elsewhere but is this an AB comparator or ABX comparator? The idea being that if you can determine which of the switch positions correspond to A and which to B with significantly better than 50 % accuracy, you’re hearing a difference.
Nice Price!
Thank you,
Anand.
The first two sections of the our ABX Comparator review has now been published at Dagogo.com
Here is the link:
http://dagogo.com/audio-by-van-alstine-abx-comparator-review-part-1-audio-store-wiring
What an unfortunate review for an interesting product!
The reviewer does not seem to understand the basic rule of experimentation: change one variable, keep everything else constant.
The reviewer does not seem to understand the basic rule of experimentation: change one variable, keep everything else constant.
...BTW: What is the the best way to level match? SPL meter set to C-weighting with the microphone facing up towards the ceiling at ear height in the primary listening position?
The proper way to level match is with a volt meter at the speaker binding posts while playing a 1khz tone, or an oscillator tone. We match it to +/- 0.003 volts. You need a good volt meter, and hearing protection while you do it. We generally match in the .75-1.0 volt range.That works if comparing different electronics while the speakers are the same. But you'll need a SPL meter when comparing different speakers.
Somewhat sadly, I'm being convinced that careful, double blind (and A/B/X) tests show that any 2 amplifiers that have flat response from 20hz-20khz, low output impedance, high input impedance, and are sized for the load (don't clip), are indistinguishable regardless of the cost. It's been a recent eye opener for me.An amplifier designer named Bob Cordell once was asked whether all solid state amps sound the same. His answer:
That works if comparing different electronics while the speakers are the same. But you'll need a SPL meter when comparing different speakers.
Granted, however does anyone really A/B/X speakers? I mean, sure we compare speakers, but they are so different sounding I can't imagine not getting 100% percent accuracy differentiating between 2 pairs of speakers using an A/B/X test. Maybe we couldn't tell which brand was which, but I can't imagine not being able to distinguish between 2 pairs. Used to compare $1000 vs $10,000 amplifiers is what double blind and A/B/X testing is about. If meeting the criteria I stated in post # 18, no one is going to be able to distinguish between the 1k and 10k amps. Eye (ear) opening.
True, you don't have to go to great effort to hear differences between speakers. But people do tend to favor the sound that is louder, so if different speakers have different sensitivities, the more sensitive one will sound louder. AVA's device allows an easy way to separately adjust the volume of each speaker so a listener can quickly switch back and forth and hear two speakers at equal loudness.