Is SINAD around 5-15 KHz relevant?

[USER]

I'd love to see what would happen here if the FCC adopted SINAD as an official unit of measure. Government overreach?

 

[Doodski]

The FTC has ruled on this and they side with me and 548 other people who bothered to comment or provide submissions to their requests.

The updated Rule requires any and all amplifiers being advertised for sale in the US from next month (August) who wish to advertise a power output of any value above 2W to rate them in accordance with the regulations or suffer the consequences.

Wow! One would think that would hit the news but nope.

 

[gags11]

Thank you for all the responses. I guess shouldn’t really be concerned about the audibility of distortion with any of the Hypex or Purifi amps at higher frequencies. Benchmark would be great, but too expensive.

I thought about the Hypex plate amplifiers, and it was tempting, but MiniDSP Flex gives me Dirac Live for room correction. Although MiniDSP Studio + Hypex plate amplifiers will work as well.

 

[DWPress]

I've been thinking a NC122 for mine will be more than adequate and hopefully longer lived than the Topping. The Neurochrome mentioned is also an excellent candidate.

Purify is overkill in this case.

 

[Tell]

Not misleading at all.

Amplifiers must be linear devices, which means they treat ALL frequencies with the same level of gain, phase and deliverable voltage and current (power) across their rated bandwidth and rated power.

No excuses.

Does this "all frequency same level gain, phase and deliverable voltage" have a real world audible use or is just for your own peace of mind?

 

[kemmler3D]

Does this "all frequency same level gain, phase and deliverable voltage" have a real world audible use or is just for your own peace of mind?

It's part of a definition of a good amplifier that I think is valid as far as it goes, but it's also not strictly required to achieve good sound quality in practice.

 

[DanielT]

-50dB to -60dB THD for 5Khz and above @ 90dB SPL from Neumann's own data for the KH120 II.

So, purely academic.

What a coincidence that you mention Neumann in this thread which deals partly with different amplifier classes and partly with the level of SINAD that can be suitable, acceptable on an amplifier.

The Neumann KH 420 seems to be a really good active speaker. It has very low distortion:

Neumann KH420 Review (Studio Monitor)

This is a review and detailed measurements of the Neumann 3-way, active speaker (monitor). It is on loan from the company and costs US $5,195. Speaker was too heavy to lug to the loft where my main system is so you have to put up with the cell phone picture above and listening tests there. Back...

audiosciencereview.com

Part of this measured distortion is a result of what the amplifier in the active Neumann KH 420 produces so what do Neumann themselves consider an acceptable distortion level on that amp? They designed a speaker whose amplifier has:

0.1% distortion or 60 dB. There is quite a big difference between that and the 90 dB or 0.003% that TS has as a target for amplifiers.

 

[Tell]

It's part of a definition of a good amplifier that I think is valid as far as it goes, but it's also not strictly required to achieve good sound quality in practice.

My definition of a good amplifier (or any other part of the audio chain) is that it's objectively below a threshold (which is not nearly as strict as many here tend to put it) where humans don't really hear the distortion, noise etc, below that I don't really care and will prioritize other things instead.
Of course the whole thing with "good engineering" I can somewhat see from a perspective of the engineers, you take pride in doing a good job because it feels nice, I do the same with whatever I do, technically good stuff behind the scenes even though it won't matter much or at all in practice. But don't overdo it though, especially if it's at a significant cost of price, size, time etc.

So if the price of lower but not audible distortion above 5khz is a more expensive, bigger size, warmer, less effective amplifier then I'm not interested whatsoever. But if there is a valid argument for audibly lower distortion then I'm curious. But tbh since my other amplifier is broken atm I'm running a very cheap TPA3118 amp with a SINAD of around 65dB and I think it sounds more than fine across the whole range so I don't think I actually care

 

[LSPhil]

My recommendation for you would be a TPA3116 based amplifier for 50 euros.

 

[DanielT]

Topping PA5 II should work well to power up a pair of tweeters.

The most important thing regarding powering up a pair of tweeters is this:

A concern with lower cost chip based class D amplifiers is load dependency at higher frequencies. Topping has managed to make that essentially a non-issue:

So good FR in the higher frequencies.

At 30 watts in the 5-15 kHz region:
5kHz THD + Noise- 92 dB
10kHz THD + Noise- 80 dB
15kHz THD + Noise- 66 dB

I could easily accept that, especially considering that we become less sensitive to distortion higher up in frequency.

Good price:
It was sent to me by the company and costs US $219 (sale). There is a plus version with higher current power supply for $289.50.

Topping PA5 II Stereo Amplifier Review

This is a review and detailed measurements of the Topping PA5 II stereo balanced amplifier. It was sent to me by the company and costs US $219 (sale). There is a plus version with higher current power supply for $289.50. The fonts are hard to see but there is not much to read anyway. A power...

audiosciencereview.com

PA5 II is a physically small amplifier. That is probably the biggest advantage compared to a large class AB amplifier. Not to mention compared to a class A based amplifier. But luckily, we haven't stumbled onto that class A track in this thread...yet.

Edit:
But if I had to choose, I would still choose a used class AB amplifier. For example, the NAD C 320BEE with its 67 watts that I mentioned in a post earlier. A good amp with SINAD around 95 (the NADs power amp alone at 5 watt), even in the higher frequencies. But that choice is mostly because the physical size doesn't bother me plus a NAD C 320BEE can be bought and sold for around $120 where I live. A safe card, so to speak, as long as it doesn't break, but it's always a risk you take if you buy used.

 

[USER]

Edit:
But if I had to choose, I would still choose a used class AB amplifier. For example, the NAD C 320BEE with its 67 watts that I mentioned in a post earlier. A good amp with SINAD around 95 (the NADs power amp alone at 5 watt), even in the higher frequencies. But that choice is mostly because the physical size doesn't bother me plus a NAD C 320BEE can be bought and sold for around $120 where I live. A safe card, so to speak, as long as it doesn't break, but it's always a risk you take if you buy used.

I regret selling my NAD C320BEE. It was my first real audio purchase. I babied the thing, even replaced the connectors and power cable with expensive audiophile versions . (Forums were so much worse back then.) Funny enough one of the last favors it did for me was to open my mind up to an objective perspective. It had served as the center of my second system after I replaced it with a monstrous Nelson Pass associated Class A 50W Forte Model 4. I always sort of hated the latter. The size, the insane amount of HEAT it produced, the cost of running it. But it had "prestige." (I do not miss those types of amplifiers AT ALL. Good riddance! For fun, I just got a toy SMSL A50 PRO mini class D amp and in all honesty I would pay you $500 to use it over that Forte.) Once I started learning about measurements it was time to sell the Forte as its resale value was at its peak. I used it one last time and then I decided to compare it to the NAD. It wasn't a proper comparison, no output matching, not real AB testing, but man, I did not hear any difference. My mind was trying so hard to find it. I didn't fully believe myself until later when Amir reviewed it and it was all there for me to see. I have so much audio gear now but I still want to get myself another one. My wife is going to kill me.

 

[MaxwellsEq]

The FTC has ruled on this and they side with me and 548 other people who bothered to comment or provide submissions to their requests.

The updated Rule requires any and all amplifiers being advertised for sale in the US from next month (August) who wish to advertise a power output of any value above 2W to rate them in accordance with the regulations or suffer the consequences.

Those regulations provide for THD+N from 250mW to rated power and across the entire audio bandwidth (20Hz-20kHz). So, whether you think HF THD+N is relevant or not doesn't matter one iota. Class D amplifiers will have to be advertised and rated the same way as all other amplifiers. They will have to be honest for once. If their amplifiers descend into noise at the low end- bad luck. If their THD+N skyrockets at high frequencies, bad luck- rate them properly.

And there's plenty of other classes, brands and designs of amplifiers that have been rorting consumers through false and misleading specifications. It's not just Class D, but a few major players have been egregious in this regard.

I'm interested in how this is going to play out; for example, will it be adopted more widely and whether consumers will be made aware. Usually manufacturers find a way round it by inventing their own metrics ("music watts", or "ultrafast power").

Since I probably can't easily detect the 2nd harmonic distortion artefacts of an 8kHz fundamental, I don't care as much about distortion at high frequency, but I care more about noise.

I can definitely hear multiple harmonics of a 100Hz fundamental, so distortion at lower frequencies seems to be much more important, to me.

There ought to be far more testing of power supply recovery after impulses into a complex load, since I've always felt that may separate two otherwise similar amplifiers.

 

[Doodski]

I regret selling my NAD C320BEE. It was my first real audio purchase. I babied the thing, even replaced the connectors and power cable with expensive audiophile versions . (Forums were so much worse back then.) Funny enough one of the last favors it did for me was to open my mind up to an objective perspective. It had served as the center of my second system after I replaced it with a monstrous Nelson Pass associated Class A 50W Forte Model 4. I always sort of hated the latter. The size, the insane amount of HEAT it produced, the cost of running it. But it had "prestige." (I do not miss those types of amplifiers AT ALL. Good riddance! For fun, I just got a toy SMSL A50 PRO mini class D amp and in all honesty I would pay you $500 to use it over that Forte.) Once I started learning about measurements it was time to sell the Forte as its resale value was at its peak. I used it one last time and then I decided to compare it to the NAD. It wasn't a proper comparison, no output matching, not real AB testing, but man, I did not hear any difference. My mind was trying so hard to find it. I didn't fully believe myself until later when Amir reviewed it and it was all there for me to see. I have so much audio gear now but I still want to get myself another one. My wife is going to kill me.

Get your wife a nice toe manicure, hands too and also the hair needs a touch-up and you'll be fine.

 

[danadam]

I'm interested in how this is going to play out; for example, will it be adopted more widely and whether consumers will be made aware. Usually manufacturers find a way round it by inventing their own metrics ("music watts", or "ultrafast power").

Since I probably can't easily detect the 2nd harmonic distortion artefacts of an 8kHz fundamental, I don't care as much about distortion at high frequency, but I care more about noise.

We need a thread "Shouldn't we downgrade the 20-20 audible range ?!"

 

[Blumlein 88]

We need a thread "Shouldn't we downgrade the 20-20 audible range ?!"

No to the thread and no to the downgrade.

 

[solderdude]

And no to a thread downgrade (knowledgeable people arguing from a different viewpoint)

Instead we should try to underline the difference between measured performance on a test bench, specification standards and minimum required performance for music reproduction and underline what matters for human hearing and transducers response to such applied power levels.

Both @restorer-john and @staticV3 are 'right' and make valid points (IMO) from their respective standpoints.
I am pretty sure John never listens to music with 200W of power through his tweeters and enjoys that music and static knows what a good measuring amp looks like on a test bench.

 

[restorer-john]

And no to a thread downgrade (knowledgeable people arguing from a different viewpoint)

Instead we should try to underline the difference between measured performance on a test bench, specification standards and minimum required performance for music reproduction and underline what matters for human hearing and transducers response to such applied power levels.

Both @restorer-john and @staticV3 are 'right' and make valid points (IMO) from their respective standpoints.
I am pretty sure John never listens to music with 200W of power through his tweeters and enjoys that music and static knows what a good measuring amp looks like on a test bench.

Well said.

 

[Blumlein 88]

One of the things I noticed is the better class D amps aren't too hot at high frequencies at high power. At lower power they are pretty good, maybe better than many class AB. Given that tweeters are unlikely to see that kind of power they most likely almost all the time have better real results distortion-wise with music. You see that in the 5 watt multi-tone charts.

OTOH, standards are standards and amps should be properly rated at their limits. Good testing gear is available for multiple tests more so than ever before in history. So the answer isn't dropping standards. It is providing the mix of tests that show us what is happening both to define the outer performance envelope and how it fits for use with music. I notice class AB designs often droop in power or have higher distortion at 20 hz. Not usually so much of a problem, but with some people doing ambitious subs and using amps for home theater, that is one place class D can excel.

There is also the idea of margins of safety. Sure most of us cannot hear to 20 khz as we age, but knowing the amps are clean and powerful to that point means it works for everyone and has a bit of margin. I mean should someone make a geezers power amp that is shite above 10 khz, but fine to that point? The same for distortion levels. The general information is people don't hear distortion if it is kept below -60 db (.1%). And that is with test tones in the range we are most sensitive. It is worse at other frequencies and worse again with music itself. I really wouldn't want to relax to less than -60 db plus the amp is only one part, so for safety -80 db (.01%) is too easy with modern tech. I would say beyond that, it likely doesn't matter, but who would complain about less distortion? None of this is anything most of you don't already know.

 

[Palladium]

So if the price of lower but not audible distortion above 5khz is a more expensive, bigger size, warmer, less effective amplifier then I'm not interested whatsoever. But if there is a valid argument for audibly lower distortion then I'm curious. But tbh since my other amplifier is broken atm I'm running a very cheap TPA3118 amp with a SINAD of around 65dB and I think it sounds more than fine across the whole range so I don't think I actually care

I don't drive passives beyond 1W anyway and I also definitely not interested in any audio gear that burns 50W+ of electrical power at idle.

 

[DanielT]

The general information is people don't hear distortion if it is kept below -60 db (.1%). And that is with test tones in the range we are most sensitive. It is worse at other frequencies and worse again with music itself. I really wouldn't want to relax to less than -60 db plus the amp is only one part, so for safety -80 db (.01%) is too easy with modern tech. I would say beyond that, it likely doesn't matter, but who would complain about less distortion? None of this is anything most of you don't already know.

You mention 80dB.

A variation on that is to make sure the amplifier has at least 10 times less distortion than the speaker.

A practical example. This tweeter with very low distortion:

SB Acoustics SB26ADC-C000-4 | HiFiCompass

The THD measurements at distance of 315 mm and voltage levels 2.83 - 8 Volt were carried out with High Pass Filter "on" (2nd order Buttreworth type, 500 Hz cutoff, HPF2-500). The THD measurements at distance of 315 mm and voltage level 11.2 Volt were carried out with High Pass Filter "on" (2nd...

hificompass.com

SB Acoustics SB26ADC-C000-4 mounted in a waveguide, which in itself can give even lower distortion, tested in a speaker here:

Revel M105 Bookshelf Speaker Review

This is a review and detailed measurements of the Revel M105 Bookshelf/stand-mount speaker. A member was interested in it so I decided to buy it through our company. The retail cost is US $750 each for a total of $1,500 for a pair. NOTE: my company, Madrona Digital is a dealer for Harman and...

audiosciencereview.com

In Revel M105 around 0.1% (60dB) tweeter distortion (at 86dB SPL),which with an amplifier with 10 times lower numbers would be 0.01% amp distortion or in other words we then land on the 80 dB you mentioned.