[deadlylover]

Quote:

Is it A/B testing circuit?
 
Just in case you plan to test 3-channel beta vs 2 channel O2, you might need 3 pole switch (to switch between real and virtual ground).

 
Yep, it's too much of a hassle to change cables for the headphones, so it'd save a lot of time to just hit a button and BAM, done.
 
The b22 is balanced, so I'd only be able to test it in 2 channel configuration.

 

[Willakan]

Quote:

I fully reserve the right to slap anybody who says the blind test results would be invalid because I'll be rolling with my prototype Obj2.

Are you just rolling in the NE5332, or are we going all out? Replacing the 4556, as already established, would invariably be a very bad idea.
If you are going to roll, I'll brave the slap and say at least do the test with the specified opamps a few times, in the same way you wouldn't stamp up and down on the Beta22 a few times before doing the listening comparison

 
Also, it struck me that nobody has ever verified the Beta22 actually measures far beyond audible limits. Based on how the dangerously (Capacitors running 100V out of spec/power supply built entirely by cutting up wallwarts and wiring the bits of about eight of them together) badly designed Singlepower amplifiers enjoyed prominence around here a while back as superb high-end amplifiers, an amplifier that doesn't actually perform that well being described as one of the best in its class would be comparatively unsurprising.
 
 

 

[bcg27]

Quote:

 
Also, it struck me that nobody has ever verified the Beta22 actually measures far beyond audible limits. Based on how the dangerously (Capacitors running 100V out of spec/power supply built entirely by cutting up wallwarts and wiring the bits of about eight of them together) badly designed Singlepower amplifiers enjoyed prominence around here a while back as superb high-end amplifiers, an amplifier that doesn't actually perform that well being described as one of the best in its class would be comparatively unsurprising.
 

 
Wow I can't believe you just compared AMB to Singlepower. That is a very serious accusation and IMO completely without merit.
 
If anyone in the Washington, DC area has the appropriate equipment to test an amplifier I would be happy to bring mine to them for testing. Please send me a PM if you are interested. My configuration is 3 channel but it should be trivial to change it to a 2 channel to get measurements from both. I plan to try this weekend to make sure my modification to 2 channel works.

 

[EddieE]

UK and EU based members might be interested in this guy - Epiphany Acoustics - A UK-based sole trader who is taking pre-orders for ready-made O2s for £100 and selling PCBs for a fiver plus shipping. Quite tempting.
 
http://www.epiphany-acoustics.co.uk/7.html
 
[size=10pt]EDIT: Sorry I realise now this has been widely disseminated already. I must have misspelled Epiphany Acoustics when I did my search for it!

[/size]

 

[mikeaj]

I'm not quite sure if that was being insinuated, especially since the circumstances with Singlepower and AMB are not the same.  The point is just that many designs seem to be largely untested, and it would be interesting to actually see them tested.  Also that it's possible to have hype without a solid basis.
 
I would be really surprised if the Beta22 performance was terrible, but I think it's very likely that it ends up doing worse in most objective benchmarks than some amps of comparable cost or lower (DIY or not), for most of the reasons wakibaki stated earlier.  This is just speculation though, until somebody gives it a proper spin in the lab.

 

[Willakan]

I wasn't insinuating that AMB designs are dangerous or fraudulent. I was just pointing out that the alarming absence of any form of rational checks and balances in the high-end means that products can achieve success sometimes disproportionate to their merits; by extension just because the Beta22 occupies that exclusive sphere does not necessarily mean it is a wonderful design that measures superbly in every regard. Admittedly, mentioning Singlepower and any other company/entity in the same sentence is always going to raise eyebrows, hence my clarification.
 
I doubt the proper measured performance of the Beta22 would be a traffic accident, but I doubt it would be anything special - in crosstalk particularly. I may be mistaken, but I vaguely recall that NwAvGuy maintains the crosstalk measurements of the AMB range get more mathematically impossible the further you go up the spectrum.

 

[francisdemarte]

I think your being a bit unfair in your portrayal of AMB.  
 
To my understanding the AMB designs have always been open source, the B22 in particular has been available to be peer examined and scrutinized for at least the last 6 years. It didn't just appear on someone's blog overnight. It still remains to be seen if the O2 design will transition from flavor-of-the-month status it is enjoying now.
 
FYI: I do not own a B22 but I do have an O2.
 
 

 

[Satellite_6]

If you could link some tests for the thing that would be cool. It doesn't really matter if no one has bothered to. Willakan has a good point. 

 

[Willakan]

I suppose I am being unfair in a way - lots of other high-end purveyors, both DIY and properly commercial, are guilty of the same thing. That amplifiers can enjoy relatively high levels of popularity in the headphone hi-fi sector without a single proper set of measurements to verify their claims of "better audio" appears utterly insane, especially when you consider the decidedly dodgy, crowd-pleasing criteria that some of them are designing to - Burson's article on the evils of opamps would be hilarious* if their products weren't taken so seriously. They are hardly alone in claiming some very strange design choices as "advantages."
 
*Apparently, opamps have thin bits, which are the "silent killers of musical texture," (presumably because they are thin). Perhaps the waveforms get squashed?

 

[DRUB]

Quote:

I suppose I am being unfair in a way - lots of other high-end purveyors, both DIY and properly commercial, are guilty of the same thing. That amplifiers can enjoy relatively big popularity in the headphone hi-fi sector without a single proper set of measurements to verify their claims of "better audio" appears utterly insane, especially when you consider the decidedly dodgy, crowd-pleasing criteria that some of them are designing to - Burson's article on the "evils of opamps" would be hilarious* if their products weren't taken so seriously. They are hardly alone in claiming some very strange design choices as "advantages."
 
*Apparently, opamps have thin bits, which are the "silent killer of musical texture," (presumably because they are thin). Perhaps the waveforms get squashed?

Yeah, I think there's a paradigm of coloured sound vs tranparent sound - sometimes design choices are made in terms of a 'hifi' rather than 'accuracy' paradigm. An analogy would be pro studio gear versus audiophile gear - there's also too much implicit trust put in the quality of the recording process of the music people listen to (as in, the methodology, not the sampling rate).
 

 

[francisdemarte]

Anyway isn't the purpose of this thread for listening impressions with, you know music...? Let's stop the measure-bation and get some listening impressions and comparisons.

 

[Pars]

Quote:

I think your being a bit unfair in your portrayal of AMB.  
 
To my understanding the AMB designs have always been open source, the B22 in particular has been available to be peer examined and scrutinized for at least the last 6 years. It didn't just appear on someone's blog overnight. It still remains to be seen if the O2 design will transition from flavor-of-the-month status it is enjoying now.
 
FYI: I do not own a B22 but I do have an O2.
 
 

Aligning Amb with Mikhail is very unfair; I realize you were just using Mikhail as an example of alluding to the fact that many high-end manufacturers provide little or nothing in the way of measured specs, and may employ rather questionable design practices, but it came off as bad form, particularly given some of the rabid behavior which occurred during the launch of this (O2) design. Amb has done an awful lot for the DIY community here over the years, and deserves a lot of credit for that.

There are published specs for the B22 here: http://www.amb.org/audio/beta22/, under the Specifications tab.
 
I haven't built or own either a B22 or an O2, but have built a few Sigma22 PSUs, and they provide excellent performance.

 

[EddieE]

I'm not personally interested in subjective ramblings about amps and DACs, that's for subjective things like transducers and music itself. Amps and DACs have set-in-stone tasks they are supposed to perform and they can be measured to see how well they perform them.
 
If someone says they like amp A over amp B with headphone C, it doesn't mean amp A is better.
 
Headphone C could have had too much bass for the person's tastes and amp A could have rolled off the bass and made it sound better to them, for example.
 
It tells you nothing useful at all.

 

[LizardKing1]

I have to be subjective here: but amp A sounds better to the individual than amp B, and if you're spending money, you want the one you like the most, not the one the specs tell you to be better.
 
I don't understand why is subjectivity incompatible with objectivity. It's like when people say "I'm a republican" or "I'm a democrat". If you whole political ideology can be resumed to one adjective, I don't think you have much to say. No one should be one thing. If NwAvGuy measured this week an amp that performed amazingly, but you hated it, would you buy it? No. The same way, if someone says a certain amp is amazing, but the FR graph is a hyperbole and it has like 20ohm output impedance, would you buy it? I doubt it.
 
I like the objective side of things because it cares only about getting the job done in the best way possible. An amp SHOULD be a wire with gain. It should have no synergy. But it should also sound good. And so far the two - sounding good and measuring well - have been working out for me. I haven't decided how I feel about tube amps. But I just don't think any way of facing audio is wrong. Of course you should have the gear that satisfies you, and of course that gear should measure as well as possible. Why must we insist that they are mutually exclusive?

 

[EddieE]

That line of thought suggests you're going to own the same set of headphones for the rest of your life, and considering in this hypothetical situation, you've just favoured the sound of an amp that significantly changed their signature - it's pretty unlikely that is going to be the case.
 
If you buy amp A now because it rolls of the bass of headphone C and you like the sound better - it's also going to roll off the bass of headphone X - which WOULD have been your perfect headphone had you not bought a rubbish amp that was now masking its potential.