Amplifiers can you hear a diffrence?

[Pjetrof]

To All,

My apologies for my English, it is not mine native language.
Also I m not a technician or engineer just a music lover.
for the last few months I ve been reading this forum.
i have a serious question to all the amplifier manufacturers to all the diy ers,
even to everyone on this forum.
If in blind testing you can not hear differences between amplifiers, why do we test amplifiers on ASR, why do
people who discuss for pages and pages amplifiers and all kind of materials used in the building of the amplifier
if all make no difference. Why buy the benchmark instead of any other amplifier of 100 watt?
why have a sinad rating if we can’t hear differences? I m not being cynical!
I can’t explain myself very good but I hope everyone understand my question.

 

[Purité Audio]

The question is indeed audability, but I believe everyone here at ASR enjoys and encourages fine engineering.
Keith

 

[BDWoody]

If in blind testing you can not hear differences between amplifiers, why do we test amplifiers on ASR,

To make sure they are competent enough that you WON'T hear a difference.

It's not that there isn't ever a difference, it's that there shouldn't be if it is properly spec'd for the job.

 

[amirm]

Well, one of the most important tests for amplifiers is amount of power versus distortion. You absolutely will hear amplifier running out of power.

 

[MZKM]

The infamous $10,000 amp challenge parameters:

• <2% THD across 20Hz-10kHz
• Channel balance matching <0.5dB
• Crosstalk >30dB

As well as some things like ”no excessive noise”.

My main thing when looking at amps is 4ohm wattage, and then I look at 8ohm wattage, which ideally should be 1/2 the 4ohm, if it’s identical than you are losing 3dB output when a speaker’s impedance swings between 4ohm and 8ohm. Then, there is the handling of difficult phase angles, which we can’t tell from specs, but having more than enough wattage will take care our that.

 

[q3cpma]

This is something I've long searched for. Any evidence that anything more than a decent power amp (Crown, Behringer, Yamaha, etc...) with a THD < -60 dB (let's say with 2nd or 3rd as the dominant harmonic) and a decent SNR is audible, even with extremely good loudspeakers?

 

[Wes]

Well, one of the most important tests for amplifiers is amount of power versus distortion. You absolutely will hear amplifier running out of power.

soft clip that mofo

 

[Pjetrof]

So I have a few answers from respected forum members, but it leaves me still in doubt.
i Understand the good engineering, and the power differences etc etc.
Just in normal use at home, normal speakers just listen to music.
is there an audible difference between hypex nc 400, 500. 1200, between Nord and Apollon and a benchmark
or a behringer or crown or Yamaha or Rotel etc all companies I think who know how to make an amplifier who exist long enough to prove they can make an amplifier, is there difference audible between Yamaha Luxman Accuphase Denon Marantz etc etc all for example 100 watt amplifiers use in normal circumstance so no clipping etc just play nice music at home?

 

[Willem]

Sometime ago I bought a new 2x250 watt Yamaha P2500s for my son in a sale and paid 300 euros for it. Its almost identical bigger brother the P3500s tested very well: https://www.homecinema-fr.com/forum...mpli-yamaha-p3500s-mise-a-jour-t30056383.html
In short, you are unlikely to hear any difference. And by the way, that Yamaha is very well made, and rugged enough for use on the road.

 

[QMuse]

So I have a few answers from respected forum members, but it leaves me still in doubt.
i Understand the good engineering, and the power differences etc etc.
Just in normal use at home, normal speakers just listen to music.
is there an audible difference between hypex nc 400, 500. 1200, between Nord and Apollon and a benchmark
or a behringer or crown or Yamaha or Rotel etc all companies I think who know how to make an amplifier who exist long enough to prove they can make an amplifier, is there difference audible between Yamaha Luxman Accuphase Denon Marantz etc etc all for example 100 watt amplifiers use in normal circumstance so no clipping etc just play nice music at home?

Very likely there is no difference you would be able to hear.

 

[BDWoody]

for example 100 watt amplifiers use in normal circumstance so no clipping etc just play nice music at home?

In the spirit of the post, I'd answer for the most part, yes.

Without getting into unrealistic or pathological conditions, or using them outside of their appropriate power range or with poorly matched speakers(same thing)...yep...pretty much.

 

[Wes]

So I have a few answers from respected forum members, but it leaves me still in doubt.
i Understand the good engineering, and the power differences etc etc.
Just in normal use at home, normal speakers just listen to music.
is there an audible difference between hypex nc 400, 500. 1200, between Nord and Apollon and a benchmark
or a behringer or crown or Yamaha or Rotel etc all companies I think who know how to make an amplifier who exist long enough to prove they can make an amplifier, is there difference audible between Yamaha Luxman Accuphase Denon Marantz etc etc all for example 100 watt amplifiers use in normal circumstance so no clipping etc just play nice music at home?

I agree you are unlikely to hear a difference - esp. if you put the Behringer or Crown in a different category, and maybe even Yamaha or Rotel.

Ultimately, you have to do a controlled listening test to ensure the subset of measurements done (out of a larger suite of all measurements that could be done) fully capture all possible sound differences (in whatever system, with whatever music sources).

The practical solution is simple (given a bolus of bucks equal to 2,000) you just get the Benchmark or best Hypex and move on.

 

[RayDunzl]

My main thing when looking at amps is 4ohm wattage, and then I look at 8ohm wattage, which ideally should be 1/2 the 4ohm, if it’s identical than you are losing 3dB output when a speaker’s impedance swings between 4ohm and 8ohm.

That, in my opinion, is just a case of underrating the 8 ohm "rating".

Example:

Acurus A250 (I have one)

250/350W rating at 8 and 4 ohms.

Magical transformation into an amplifier that "doubles down":

175/350W re-rating and boom - it doubles into half the impedance

---

What made me realize this?

Krell FPB 600 review:

Rated as 600/1200/2400W into 8/4/2 ohms

"For example, when I tested the FPB 300, this nominal 300W amplifier actually produced 470Wpc into my 7.5 ohm high-power test load. The '600 matched this achievement by measuring 945Wpc continuous into the same load (935Wpc into a scaled 8 ohms)."

I will presume it won't throw 3780W into 2 ohms, using the measured 8 ohm performance.

---

On the other hand, I figure any amp will double the power into half the load, as long as you aren't exceeding its limit to maintain voltage output, and assuming a very low output impedance.

 

[amirm]

This is something I've long searched for. Any evidence that anything more than a decent power amp (Crown, Behringer, Yamaha, etc...) with a THD < -60 dB (let's say with 2nd or 3rd as the dominant harmonic) and a decent SNR is audible, even with extremely good loudspeakers?

There is one test although not all the detail that you mention is there: https://www.audiosciencereview.com/...ts-did-show-amplifiers-to-sound-different.23/

 

[Blumlein 88]

This is something I've long searched for. Any evidence that anything more than a decent power amp (Crown, Behringer, Yamaha, etc...) with a THD < -60 dB (let's say with 2nd or 3rd as the dominant harmonic) and a decent SNR is audible, even with extremely good loudspeakers?

Wish I knew more about the Swedish Audio Society series amp tests. Despite expectations, they only ever had one amp that was transparent. These tests were done with a real loudspeaker load.

Or more importantly, I wish someone else would replicate them. I've done the same thing myself years ago. It was a very revealing test.

Assuming the same results of all amps (or most) being detectable the question might be why, what parameter unmasked them.

 

[Mnyb]

That, in my opinion, is just a case of underrating the 8 ohm "rating".

Example:

Acurus A250 (I have one)

250/350W rating at 8 and 4 ohms.

Magical transformation into an amplifier that "doubles down":

175/350W re-rating and boom - it doubles into half the impedance

---

What made me realize this?

Krell FPB 600 review:

Rated as 600/1200/2400W into 8/4/2 ohms

"For example, when I tested the FPB 300, this nominal 300W amplifier actually produced 470Wpc into my 7.5 ohm high-power test load. The '600 matched this achievement by measuring 945Wpc continuous into the same load (935Wpc into a scaled 8 ohms)."

I will presume it won't throw 3780W into 2 ohms, using the measured 8 ohm performance.

---

On the other hand, I figure any amp will double the power into half the load, as long as you aren't exceeding its limit to maintain voltage output, and assuming a very low output impedance.

Yes the impedance is the key no good amp width low output impedance actually amplify less at lower impedances it might run out of voltage or current sooner and hit a limit . So I would not look at the 8/4 ohm spec to hard just that it should not be as bad as many AVR’s .

You are running out of voltage or current rarely power , because the crest factor of typical music the RMS value is much lower than the peaks . That’s why funny enough testing with sines makes the amps much hotter ?

I think there is a common misconception that I don’t need that much power I don’t listen that loud , so you may be underpowered and drive your amp close to its limits .
Many speakers tested at ASR do have low impedance dips that may stress a simple AVR for example.

 

[QMuse]

There is one test although not all the detail that you mention is there: https://www.audiosciencereview.com/...ts-did-show-amplifiers-to-sound-different.23/

Interesting. However, both (relatively powerful) amps were clipping app 1% of the time only to achieve 90dB of listening level. Is it because of the Acoustat electrostats used in test? It may as well be that impedance of those speakers went very low at some freqs and one of the amps was better at handling such situation.

 

[Mnyb]

Two things that are hard to define , when are we inside the amps spec and it behaves well ?
What is a difficult speaker what can be expected ? some pathological designs like the old apoggee's needed amps costing more than the speakers , it became a fetish in itself to have enormus monoblocks on the floor

It's hard for amir to test at limits because he does not want to destroy eqipment , the stability and recovery behaviur at clipping can be an interesting thing to see .
Also here active speakers shine not all amps clipps at same time in your active speakers so if the bass amp hits the rails for brief moment that may not impact midrange for example excpet that the bassdriver may emmits sounds it's not suposed to do . And if your sub limits briefly your main will be unafected if you have active subwoofers

My takeaway is that it's better to buy that japanse 150wpc amp instead of some british cottage industry 20wpc class A amp any day.

 

[QMuse]

When I was buying amp for my system I went for THX Ultra certified amp. THX never disclosed the exact values for each parameter to achieve but here's the list what metrics is tested:

Reference Output Voltage
Voltage Gain
Output Current
Output Source Impedance
Overload Restoring Time
Stability with Capacitive Load
Harmonic Distortion and Noise
Modulation Distortion
Difference-Frequency Distortion
Noise Output Voltage
Phase Response
D.C. Offset at the Output
Hum
Crosstalk
Acoustic Noise Level
Mechanical Noise
Input Sensitivity
Input Impedance
Output Impedance
Load Impedance Range
Voltage Output Capability
Current Output Capability
Transient Output Capability
Transient Overload Recovery Time
Asymmetrical Clipping
Frequency Response
Phase Response
Phase Margin
Time
Total Harmonic Distortion
Intermodulation Distortions
SMPTE IM Distortion
IHF IM Distortion
DIM 30 Distortion
Noise
Hum
Radiated Interference
Conducted Interference
Crosstalk

Most of the certified amps are multichannel and manufacturer has to pay for certification test even in the case when amp failed to get it.

It would be interesting to see one of those THX certified amps/AVRs tested here.

 

[Mnyb]

"Noise output voltage" is that the absolute noise level , the usual specs are only relative "SNR ratio" . Absolute levels of residual noise is interesting it's a problem in the cheaper active speakers ASR tests for example ?