Pass ACA Class A Power Amplifier Review

[JohnYang1997]

I am shure that I am not.
How can you explain that Dacs or Amps who mesaure the same sound different?

I need your evidence first.
1, dacs that measure the same
2, amps that measure the same
3, proof that you hear difference between any pair of the devices in 1 or 2 (properly designed and executed blind tests)
Then I can try to answer.

 

[JohnYang1997]

Analogy:
When will you give my money back?

I need to have the evidence that you indeed owe me money before talking about when and how you give me the money. Logical.

 

[jan.didden]

I am sure that I am not.
How can you explain that Dacs or Amps who measure the same sound different?

There are two parts (at least) to an answer. Firstly, what you think as 'sound different' almost always is perception based, not objectively. There are numerous examples where people were fooled by mentioning another brand than what was actually playing, and changed their preference depending on the brand name not the actual unit playing. And that is completely normal. There's a multi-trillion $ marketing industry out there based on those facts.

The other thing is that not always we measure enough. It's easy to measure the freq response and distortion of two DACs, see that they are the same and be surprised they sound different. But what about the jitter, to mention just one example?

Jan

 

[Observer]

Ear wax?

Good try
it is because we can‘t measure all aspects that have influence on sound , so we measure what we know or what we can.

 

[simbloke]

You can’t measure the “sound”, with todays knowledge you can measure just some parts of it.
And using only that in count, you miss the bigger part.

Well I'm glad you came here with your expertise to set us all straight then.

 

[JohnYang1997]

Well I'm glad you came here with your expertise to set us all straight then.

lol

 

[Frank Dernie]

it is because we can‘t measure all aspects that have influence on sound

Yes we can.
There is only frequency, amplitude and phase, all those are measurable to a level beyond human hearing. There is an electrical signal going into the box and one coming out. We can measure the effect of the box better than our ears. Fact.

 

[pkane]

Good try
it is because we can‘t measure all aspects that have influence on sound , so we measure what we know or what we can.

Of course! One of those things we can't measure is ear wax and its influence on sound.

 

[Observer]

I need your evidence first.
1, dacs that measure the same
2, amps that measure the same
3, proof that you hear difference between any pair of the devices in 1 or 2 (properly designed and executed blind tests)
Then I can try to answer.

Yes we can.
There is only frequency, amplitude and phase, all those are measurable to a level beyond human hearing. There is an electrical signal going into the box and one coming out. We can measure the effect of the box better than our ears. Fact.

Thesr is much more, but for those you mention we know .
Why good tubeamp can sounds better than transistor amp with less declared distortion ? Or why class A amps have better stereo sondstage than clas AB , can you measure soundstage?

 

[maltux]

I have plenty of ear wax I can share.

 

[VeerK]

I’m getting exhausted by the constant influx of new users who keep signing up to defend their favorite product’s “magic”

 

[pkane]

I have plenty of ear wax I can share.

Donate it to science! We need to get to the bottom of these "unmeasurable but audible" factors!

 

[Frank Dernie]

It is not hard to find two Dacs who measrment are

Thesr is much more, but for those you mention we know .
Why good tubeamp can sounds better than transistor amp with less declared distortion ? Or why class A amps have better stereo sondstage than clas AB , can you measure soundstage?

We don't need to measure soundstage.
There IS only an electrical signal.
It starts out at the microphone where it is (should be) proportional to the air pressure fluctuation we call sound at the microphone capsule.
This signal is the beginning. Everything between the microphone signal, be it recorder or amplifier will modify this signal in ways that can be completely measured, since there IS only voltage, amplitude and phase. It then gets to the speaker where a fluctuating pressure is recreated and we can hear it.
All the electrical parts can be measured more accurately than ears. If there is an audible difference we can measure it.
Higher distortion? Some people seem to like it.
Maybe the speakers being used have a frequency response which is preferred when it is modified by the high output impedance of a valve amplifier or a low feedback amplifier.
All this is measurable and explainable.

 

[LTig]

Feel the heatsinks of you typical Class A/B amplifier; if they are stone cold or barely warm, the bias is just the minimum to avoid onset of high crossover distortion, nothing more. Especially with amplifier manufacturers who are concerned with energy usage, this is most likely to be the case.

Read Douglas Self's book about power amplifier and you will see that this is not true. Each amplifier has an optimum bias current in the output stage and this is a comparatively small value. Increase the bias over this point and distortion does increase and not decrease, as is falsely assumed by many.

 

[LTig]

Good try
it is because we can‘t measure all aspects that have influence on sound , so we measure what we know or what we can.

Not again, please ...

 

[LTig]

Why good tubeamp can sounds better than transistor amp with less declared distortion ? Or why class A amps have better stereo sondstage than clas AB , can you measure soundstage?

Frst one has to make sure with a DBT under controlled conditions that there is an audible difference at all. This is were most audiophiles fail.

For tube power amps the higher output impedance combined with the speaker impedance certainly influences the frequency response, usually to a little loudness curve with many 2-way speakers (more bass, more highs). Of course in a listening test this combination wins hands down over a decent solid state amp. Fortunately it is very easy to get the same sound out of a solid state amp: just add a small power resistor in series with the speaker and you're done. Much cheaper than any decent tube amp and - that is the best part - you can undo the change.

 

[Observer]

We don't need to measure soundstage.
There IS only an electrical signal.
It starts out at the microphone where it is (should be) proportional to the air pressure fluctuation we call sound at the microphone capsule.
This signal is the beginning. Everything between the microphone signal, be it recorder or amplifier will modify this signal in ways that can be completely measured, since there IS only voltage, amplitude and phase. It then gets to the speaker where a fluctuating pressure is recreated and we can hear it.
All the electrical parts can be measured more accurately than ears. If there is an audible difference we can measure it.
Higher distortion? Some people seem to like it.
Maybe the speakers being used have a frequency response which is preferred when it is modified by the high output impedance of a valve amplifier or a low feedback amplifier.
All this is measurable and explainable.

Unfortunately or fortunately, experienced listener can hear differences in hi-end system that we can't measure with equipment.
Quality hi-fi system behaves like telescope, and expose every detail, component signature, timbre and soundstage.
In audio ears can sometimes see better than eyes.
I have feeling that some of members here don't have much experience in listening , they just measure.

 

[JeffS7444]

Unfortunately or fortunately, experienced listener can hear differences in hi-end system that we can't measure with equipment.
Quality hi-fi system behaves like telescope, and expose every detail, component signature, timbre and soundstage.
In audio ears can sometimes see better than eyes.
I have feeling that some of members here don't have much experience in listening , they just measure.

 

[maltux]

I know the Covid lockdown is making people batty including myself but why do we have this discussion, in one form or another, over and over again. Should someone really be interested they would read all 24 pages of posts and decide if this forum was for them or not.

 

[amirm]

Unfortunately or fortunately, experienced listener can hear differences in hi-end system that we can't measure with equipment.

Who says what they are saying is true? Did they take a test where we know the answer in advance to know they are right?