Amplifiers bench tests results-should we care or not, regardless of audibility, are those thresholds such as -100, -80, -40 dB THD+N, IMD etc.useful?

[PENG]

If you open your thread, look at the upper right corner- you should see a box with 'Watch' on the left, three dots and 'Edit Thread' at the right. Click on 'Edit Thread' and you'll be able to make the changes.

Thank you, I thought I would click the edit box that won't let me edit the title. The 3 dots one did the trick.

 

[highfigh]

Since you mentioned noise, the specs of the Sony you highlighted included SNR and THD so that's good. Sometimes people focused too much on THD and neglected SNR; and ended up being disappointed by audible noise such as hiss and hum. That's probably not much of an issue nowadays, as THD+N has been widely used so in most cased, one doesn't need to seek out the noise spec.

I had two other Sony integrated amps before that one and all three had great specs & sound. The service manual for the second one (TA-F6b)stated the full frequency response as DC-100KHz +0dB/-1dB, -115dB S/N with the inputs shorted and 100W/ch output @8 Ohms, <.003% THD, 20-20KHz.

That 100W/ch was a bit conservative- when I worked for a Sony dealer, we had a service tech who had worked in the DC Drives division of Allen Bradley and servicing audio equipment was a piece of cake for him, but he was also passionate about audio and he was really good at servicing it. I asked him to do some performance tests on my Sony TA-F6b and when I called to ask how it went, he said, "Well, there was a problem" and continued to say that a diode in the power supply rectifier section had died, so he replaced all of them with, in his words, "something that can handle about eight of this amp". This was on a BPi Distortion Analyzer, which was very good, at that time. The printout showed that it developed 176W/channel at rated distortion with 8 Ohm loads.


The service manual can be found on this link and it's a cop of the original-

Sony TA-F6 Integrated Stereo Amplifier Manual | HiFi Engine

www.hifiengine.com

The second & third models had MM and MC phono preamps that provide enough gain for a Denon 103d cartridge, which has unusually low output- many new models come close, but they fall short of the gain/low noise of these semi-humble Sony models and the TA-F6b MC section provided 70dB, which is 10dB more than all but a few modern models (most are rated at 60dB gain for MC).

My first Sony integrated amp was rated at 30W/ch, but all of the magazine tests showed 56W/ch, all tests at rated distortion. The phono section was only MM, but was sensitive enough that I could use a standard output MC cartridge and still have a usable SPL, without rotating the volume control past 12:00. I had a newer preamp and the MC preamp wasn't more sensitive than that little thing!

 

[3db]

You all know where I sit on this one.

 

[mtrycrafts]

You all know where I sit on this one.

No, tell us, I forgot. Been a while.
Was it the front row or the back row., left side or the middle.

 

[AcuDefTechGuy]

You all know where I sit on this one.

On what kind of SINAD the speakers have?

 

[Trell]

On what kind of SINAD the speakers have, instead of the electronics?

Like if the speakers have a SINAD of -50dB (0.1% THD+N) from 200Hz-10kHz, why all the talk about the electronics SINAD?

If the speakers have a THD+N of 0.1% and the electronics have a THD+N of 0.0000000001%, the overall THD+N will still be 0.1% (SINAD -50dB).

We all know by now that you don’t mind buying or selling new audio electronics with a THD+N of over 1%, even if it’s very expensive. Good for you!

 

[highfigh]

On what kind of SINAD the speakers have, instead of the electronics?

Like if the speakers have a SINAD of -50dB (0.1% THD+N) from 200Hz-10kHz, why all the talk about the electronics SINAD?

If the speakers have a THD+N of 0.1% and the electronics have a THD+N of 0.0000000001%, the overall THD+N will still be 0.1% (SINAD -50dB).

It’s hilarious when guys say, “Man, my amp has a SINAD of -110dB, so it sounds so clean” when their speakers probably have a SINAD of -50dB (THD+N 0.3%).

What about self noise from the cables?

 

[AcuDefTechGuy]

We all know by now that you don’t mind buying or selling new audio electronics with a THD+N of over 1%, even if it’s very expensive. Good for you!

I’ve owned electronics from ATI, Bryston, Denon and Yamaha. And all of them probably have THD+N better than 0.007% at 1kHz.

However, all of the speakers I’ve owned like Revel Salon2, B&W 802D2, KEF Reference 201/2, Linkwitz Orion 3.2.1 and RBH SVT Towers probably have THD+N of no better than 0.1% (SINAD -60dB) from 20Hz-20kHz.

 

[Cos]

Perhaps it’s more telling to include a ranking among the factors - to paint a picture, sort to speak.

How would you Rank your Order of Importance from most to least important ?

1. Measurements > Features > Price > Warranty/Support/Reliability > Brand name ?
2. Brand name > Warranty/Support/Reliability > Features > Price > Measurements ?
3. Warranty/Support/Reliability > Brand name > Features > Price > Measurements ?
4. Price > Measurements > Features > Warranty/Support/Reliability > Brand ?

For me personally, I would vote for #2 or #3, which = Pride of Ownership.

I mean if money-no-object, who wouldn’t get McIntosh or Bryston or Mark Levinson or Krell, etc., correct?

If you could have these brands for FREE vs. anything else that has better SINAD, what would you get?

• I heavily weight #3 because even the best shiznit breaks down
• #2 would be my second, partially because the brand name implies that I like their warranty and, not going to lie, I like the cosmetics.

That being said the ATI amp is butt ugly, dead silent and sounds great, but butt ugly

 

[TLS Guy]

The problem is a focus on THD. Peter Walker showed with listening panels that THD below 2% was not easily identified by blinded listening panels.

However small amounts of crossover distortion, which is the curse of AB amps, was easily identified in small quantities. This is what led to his development of the curent dumping amp, which have zero crossover distortion. I do believe that is why these amps are so easy on the ear and listenable.

I do not know its prevalence in class D amps, but I suspect it is also non existent. I abandoned class AB amps a long time ago.

 

[AcuDefTechGuy]

• I heavily weight #3 because even the best shiznit breaks down
• #2 would be my second, partially because the brand name implies that I like their warranty and, not going to lie, I like the cosmetics.

That being said the ATI amp is butt ugly, dead silent and sounds great, but butt ugly

I was going to include Aesthetics in the ranking because it is very important.

1. Measurement> Features> Price >Warranty/Support/Reliability >Brand >Aesthetics?
2. Brand > Aesthetics > Warranty/Support/Reliability > Features > Price > Measurements ?
3. Warranty/Support/Reliability > Brand > Aesthetics > Features > Price > Measurements ?
4. Price > Measurements > Features > Warranty/Support/Reliability > Brand> Aesthetics?

 

[AcuDefTechGuy]

The problem is a focus on THD. Peter Walker showed with listening panels that THD below 2% was not easily identified by blinded listening panels.

However small amounts of crossover distortion, which is the curse of AB amps, was easily identified in small quantities. This is what led to his development of the curent dumping amp, which have zero crossover distortion. I do believe that is why these amps are so easy on the ear and listenable.

I do not know its prevalence in class D amps, but I suspect it is also non existent. I abandoned class AB amps a long time ago.

I’ve read one online publication that made a general statement that THD in speakers range from 0.1% to 10% depending on frequency range and volume - higher Frequencies and higher volume would produce more THD.

AVR THD+N is much better at 1kHz. I think among the worst I’ve seen is about 0.03% THD+N for cheap AVR.

But what is “crossover distortion”?

We’ve all seen Crossover measurements like 80-90 dB at 1kHz and 60 at 20kHz. Is this what you are referring to?

Like THD+N and other measurement parameters, there is an audible threshold.

When you say “small amount of crossover distortion”, are saying 90dB crossover vs. 85dB crossover?

 

[TLS Guy]

I was going to include Aesthetics in the ranking because it is very important.

1. Measurement> Features> Price >Warranty/Support/Reliability >Brand >Aesthetics?
2. Brand > Aesthetics > Warranty/Support/Reliability > Features > Price > Measurements ?
3. Warranty/Support/Reliability > Brand > Aesthetics > Features > Price > Measurements ?
4. Price > Measurements > Features > Warranty/Support/Reliability > Brand> Aesthetics?

Power amps were originally intended to be kept out of sight, and actually should be. This is another reason to transition to amps being in the speakers.
In my AV room you do not see any of the nine two channel power amps. You do see them in the other two systems, but fortunately they do not look that bad.
Years ago audio furniture kept power amps out of site.

My turntable case is actually a 'nod' to those years, now long ago.

They were not quite like that. There would not have been doors, but a lid, hinged at the rear, with a turntable and tape deck sunken below the lid. There power amps would be below towards the rear. There would have been space for record and tape storage below. That is exactly why Quad equipment is designed that way. It was designed to be panel mounted with no screws at the front and just two bolts firmly securing the units from the rear.

Back in the fifties, sixties and seventies, all manufacturers made provision for panel mounting preamps, radio tuners, and tape preamps. Turntables and tape decks were also mounted on top. Turntables did not come mounted on plinths until the late sixties.

In those days audio installations and the furniture were more elegant and a power amp would never have been seen in the room. It was the Japanese that broke the mold so to speak, with everything in full view including the wires.

I have found a picture of the sort of Hi-Fi cabinets in use back then. Here is a Quad Garrard system, form the sixties era I suspect.

That is the sort of elegance we need to recapture.

 

[TLS Guy]

I’ve read one online publication that made a general statement that THD in speakers range from 0.1% to 10% depending on frequency range and volume - higher Frequencies and higher volume would produce more THD.

AVR THD+N is much better at 1kHz. I think among the worst I’ve seen is about 0.03% THD+N for cheap AVR.

But what is “crossover distortion”?

We’ve all seen Crossover measurements like 80-90 dB at 1kHz and 60 at 20kHz. Is this what you are referring to?

Like THD+N and other measurement parameters, there is an audible threshold.

When you say “small amount of crossover distortion”, are saying 90dB crossover vs. 85dB crossover?

No, the point is that crossover distortion does show up as THD. The point is that not all THD is created equal. Crossover distortion occurs as the wave crosses the zero axis, and is highly objectionable.

This cartoon exaggerates, but shows what I mean.

The more an amp is biased to class B and away from A then the crossover distortion increases. For some reason the ear is much more sensitive to this type of distortion compared to the distortion at the peak of the wave. Tube amps do not suffer from this distortion and neither do any class A amps.
I do not know how class D amp rate here, but I would suspect they are free of it.

 

[PENG]

No, the point is that crossover distortion does show up as THD. The point is that not all THD is created equal. Crossover distortion occurs as the wave crosses the zero axis, and is highly objectionable.

This cartoon exaggerates, but shows what I mean.

The more an amp is biased to class B and away from A then the crossover distortion increases. For some reason the ear is much more sensitive to this type of distortion compared to the distortion at the peak of the wave. Tube amps do not suffer from this distortion and neither do any class A amps.
I do not know how class D amp rate here, but I would suspect they are free of it.

That is quite true for class B amps, but for class AB amps, the "well designed ones" anyway, don't really produce enough crossover distortions to the point that it would become audible and/or objectionable.

As you said, crossover distortions does show in in THD so amps such as many class D, and even class AB amps such as Benchmark's AHB2 that has distortions at a little more than 0.0002% at as low as 50 mW, how much of that were crossover distortions?

I know you really like those current dumping amps that don't suffer from crossover distortions at all, but most well designed class AB amps, while bound to have some crossover distortions, anything at the 0.05%, that is -85 dB is not going to be heard by humans, especially when the noise floor of most very quiet room will be above 20 dB to begin with. Also important to keep in mind, crossover distortions in class AB amps really shouldn't exist either at normal listening level when the amp's output is above 500 mW or so.

 

[AcuDefTechGuy]

how much of that were crossover distortions?

Excellent point.

Let’s say we have all kinds of different distortions including XO-THD.

If TOTAL distortion (all distortions combined) + Noise is 0.003%, then logic tells us that XO-THD is even less than 0.003%.

Even more than that, if the speakers have a TOTAL DISTORTION of 0.1% from 20Hz-20kHz, then logic also tells us that the TOTAL SYSTEM (AVP + Amp + Speakers) DISTORTION will more than 0.1% THD. And that’s not even including the NOISE from the room.

 

[lovinthehd]

I was going to include Aesthetics in the ranking because it is very important.

1. Measurement> Features> Price >Warranty/Support/Reliability >Brand >Aesthetics?
2. Brand > Aesthetics > Warranty/Support/Reliability > Features > Price > Measurements ?
3. Warranty/Support/Reliability > Brand > Aesthetics > Features > Price > Measurements ?
4. Price > Measurements > Features > Warranty/Support/Reliability > Brand> Aesthetics?

Aesthetics isn't something I particularly care for the reviewer's opinion on, that's a personal thing and not particularly high on my list either...it'd be nice to have a reliability rating but how can you do that with a new product? I guess "4" would be closest to my ranking.

 

[AcuDefTechGuy]

Aesthetics isn't something I particularly care for the reviewer's opinion on, that's a personal thing and not particularly high on my list either...it'd be nice to have a reliability rating but how can you do that with a new product? I guess "4" would be closest to my ranking.

What about warranty and customer support (repairs, shipping cost)?

 

[lovinthehd]

What about warranty and customer support (repairs, shipping cost)?

Yeah I review all the pertinent information relating to purchasing....I don't need the reviewer to do that altho if he points out your favorite about paying for shipping in one direction....or two....would be fine. How can they review shipping cost?

Of course the question is about a bench test....not a subjective review particularly.

 

[AcuDefTechGuy]

How can they review shipping cost?

Whether the repair shipping is Free or not.