Simple Killer Amp - Listening impressions

[AKSA]

Greg,

I noticed your comments on opamps, and the conundrum of subjective listening tests. I agree emphatically, but I'd be interested to know if you feel you can measure and quantify these subjective differences, and if so, how?

Cheers,

Hugh

[amplifierguru]

Hi Hugh,

Yes, I'm still trying to work that out - how to measure such differences. I might point out that the tests were done with a well stabilised nested amplifier configuration that would take all the op-amps tested without alteration. Then it was simply plug and play. we only had one unit so we would turn it off, let it deenergise, plug in the next chip, power it up and listen. Load impedance was high. The differences were small but clearly, and unanimously perceptible.

Unfortunately, I never got around to taking it further. So it remains unsolved. I may have gotten different results with each optimised for the partic op-amp. It was 2 days before the Bangkok Hi Fi show and the pressure was on.

Cheers,
Greg

[AKSA]

Greg,

I'm glad you see it the same way. This subjectivity, and lack of metrics, worries me, and I suspect serious designers need to consider how to quantify these effects because they are the root of the subjectivist arguments, which often form the basis of consumer selection.

I guess it's what makes this an art as well as a science.

Cheers,

Hugh

[crazyhub]

Hi Supertib,

well without any feelings being hurt how do you compare the ASKA to the SKA ?......

Hard for me because :

1) as previously said, the SKA was a prototype, not fully completed with top components.
2) I’m working in the intellectual proprietary domain and thus I have a huge respect for creators like Hugh and Greg.
3) Even if the words used to compare two components were right for the majority of listeners, the feeling of the existing differences is mainly a matter of personal taste and/or linked components.
4) I made the listening sessions at low to average spl. However, regarding that both seamed to well control the drivers, I guess it will be no problem at higher spl if your speakers do have average efficiency (say approx 90db), even with heavy metal music.

Thus, my answer will be short:

Both have a large amount of qualities regarding the classical/commonly perceived listening criterions; bandwidth, dynamic, details, soundstages and “fluidity” are top-class: if there are differences in these domains, they are slight.
The main and uncommon qualities are:
- the SKA seams to have really NO distortion at all, giving a very soft listening: if you hear a harsh sound, it doesn’t come from the amp. The sizes of imaging are “true” it’s to say that they grow up very linearly with spl.
When you listen to the SKA, you think: this amp is the “righter” I have never heard because even if there is some lack of what I pointed out in previous posts, you are absolutely unable to find fault with its sound.
- the AKSA has a more generous approach. Its mid-range is very solid, never does it sound lean. However, this particularity isn’t due to a lack of frequencies linearity. Also, and consequently, the sizes of imaging are a bit larger than average.

[mastertech]

aksa-Greg,

I'm glad you see it the same way. This subjectivity, and lack of metrics, worries me, and I suspect serious designers need to consider how to quantify these effects because they are the root of the subjectivist arguments, which often form the basis of consumer selection.

I guess it's what makes this an art as well as a science.

Cheers,

Hugh
---------------------------------------------------------------
i asked carzyhub for some clues on that, but obviously the views
of different people will vary and thus argumements flourish, with
that in mind the lack of metrics has again to do with technical
specs people on the subjective camps are reluctant to define such
sound qualities without arguments, i think if we as manufacturers
take time to understand what they are saying we can come up
with the right mixture to satisfy their tastes in music but dont forget a good amp is primarily technical spec dependent without that we have no art

Reagrds

[Supertib]

So either way the AKSA and the SKA are wonderful designs.....That is good to hear.....but honestly I still don't understand quite what you said LOL.....I am definiteely not the brightest bulb on this tree LOL......but I am glad to be here regardless....

When you say the AKSA is a more generous design, does this meen it seems to be a little more forgiving of poor music source ?

The speakers I am building are a 96db sensitivity psuedo line array, the kit is offered by RAW accoustics called the RA8....This is a Canadian company so I like to deal Canadian when I can

I am a gadget freak, and a newbie to DIY audio, but I am here to learn and play and am not here just to save money...with the being said I am as well am curious about the DEQX systems....which needs me to run a amp for each driver...they suggest using amps to suit each drivers characteristics.......So i was wanting to know how each amp performs and which would be better for what.....I know both are amazing amps I am jusr curious how you would compare them in laymens terms so an average Joe like me could understand.

[AKSA]

Supertib,

Let me just indulge myself and describe the landscape a little.

There are two schools in audio, objective (Greg, SKA) and subjective (Hugh, AKSA). As a general rule, these camps don't talk, and tend to say interesting, colorful things about each other.

The objective school is largely populated with professional sound engineers, usually EEs, who are taught rigorously that if you can't measure anything it isn't there. Their training is very thorough, and highly mathematical in nature. This is all good.

The subjective school is made up of ageing hippies, often unqualified (and often despised!) people, alternative types who like sitting beneath triangles near crystal and razor blades, and a few highly rational audiophiles who have become disillusioned with the math and measure approach of the engineers and marketers. You get the picture. These guys, examples of which might be John Bedini and Shun Mook, say that everything matters, materials, resonance and wire are paramount, and that the figures mean nothing at all, it's all about how it sounds, Daahling......

Obviously a balanced individual would tend to pick the eyes out of both camps, and this is both rational and appealing.

Further complicating this picture is the existence of two completely different technologies - tubes and solid state. And they sound very different, too, with SS giving huge slam, impact and resolution, and tubes giving diminished slam, but marvellous gloss, imaging, engagement and romance to the music.

The measurement of audio amplifiers has until now been confined to frequency response - which is transparent and which has audible effect - and total harmonic distortion, which is vague, imprecise, and appears to bear little correlation with what we actually hear as humans. Practioners like Earl Geddes have done a lot of work on this problem, but it falls to the realm of a sub-discipline called Psychoacoustics which is not the same as audio engineering. There are other tests, too, but they are more esoteric, such as the stability test at 1KHz with square wave into a capacitive load. This test is very useful as speaker loads vary widely. THD is a hotly debated topic, but most designers these days concede that the harmonic structure of the distortion is important, with a low order distortion spread appearing to sound much better than a high order one.

Without playing into the hands of either camp, I would point out that the education process, particularly at Engineering school, tends to constrain options and dampen creativity. This is because for most of the world's technical problems there is a range of tried and tested solutions which are carefully taught and assiduously learned at University. Often the unqualified or 'inadequately educated' are too ignorant to fully understand the important details, so they flail about, trying this and that, and now and again something which works well pops out and eventually, after a lot of educated outrage, it is accepted by the world at large.

In closing, it's important to note that progress depends on unreasonable, often unqualified, men. This is a rephrasal of a GB Shaw comment from last century, but it's very true as the reaonable man seldom deviates from the tried and true pathway by his very nature.

When you invest in a technology you might be interested to understand the philosophy of the designer, because everything flows from the philsophy, regardless. Be assured that although Greg and I are from different camps, we do have quite a bit in common.

Cheers,

Hugh

[ANDYLASER]

Hugh, what a thoroughly enlightening response. Maybe the 2 camps should get together for a friendly beer?

[jam]

Friendly beer?...........................

http://www.wimp.com/beerfight/

[macka]

Hugh,

I think there is a third school, people like Nelson Pass and John Curl who fit into neither of the above.