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 we don't test, or don't read the test results, we won't be biased to think the distortions may result in poorer sound quality. Then we may never know there might be design and/or implementation issues with the devices. Is it better not to bother with those test result at all if you can't hear the negative effects anyway? There are other measurement criteria such as cross talk, frequency response, damping factor (output impedance), intermodulation distortions that can affect sound quality as well and should be included in our considerations. Edit: underlined this sentence in case people may miss it.

I included two examples that may help decide on whether bench tests are needed regardless. One is the Starke power amps that both Audioholics.com and Audiosciencereviews.om have reviewed and bench tested. The other is a just published review of a Purifi based amp on ASR.

Edit: Note that I use these two examples not because I believe SINAD is the most important criteria, but because these examples shows measurements can help discover issues that even the manufacturers may not be aware as such occurrences could have been totally unexpected. Such unexpected issues may not affect sound quality at all, but even the manufacturers would likely agree they need to be fixed. Another example I could have included is the one Gene found in his testing of the Yamaha CX-A5200 that @AcuDefTechGuy would remember very well. Yet, that happened to be also anomalies with SINAD, one that I am well aware to be not repeated too many times as many people are already tired of hearing/reading about.

Starke Sound Fiera4 4 Channel Amplifier Benchmark Test Results | Audioholics
Buckeye 3 Channel Purifi Amp Review | Audio Science Review (ASR) Forum

Buckeye did response to the review within 24 hours:

Buckeye 3 Channel Purifi Amp Review | Audio Science Review (ASR) Forum

This was not expected and was not an attempt to have a known/flawed product pushed through review.

While we did robust testing during development and prototyping, I cannot account for why this issue was not identified or observed early on. But I do take full responsibility.

As Amir briefly acknowledged, now that we are aware of and able to reproduce the issue on our end, we have been testing furiously to identify the exact cause so we can produce a fix.

Transparency and communication with the community has been one of the "pillars" I've tried to build my business upon. As soon as we identify the exact issue and the appropriate fix, it will be implemented ASAP, including for current customers as needed.

Yes, because not all of the threshold of audibility for various measurements are known

The latter's (Buckeye's Purifi amp) THD+N is in order of magnitude better than Starke, but for real world use, under most conditions the user would very likely not be bothered by the level of THD+N.

Starke:

 

[Trell]

Starke should take a look at Buckeye on how to communicate with customers and responding to reviews.

 

[AcuDefTechGuy]

I vote that I care about the results, which is the same case since I first started in this hobby as a teenager.

I think we all want the same thing here - the best SNR, best THD+N, best Crosstalk, best power output, best damping factor, best everything. Who wouldn’t want SINAD of 110dB?

But just like everything in life, sometimes things don’t go according to plan. And how we differ is our level of tolerance or acceptance.

We all have our own personal standards. For some, it’s the SINAD of -100dB (0.001%), for others it’s -90dB (0.003%) or -82dB (0.008%) or -80dB (0.01%).

My Yamaha AVR (RX-A3080) is -82dB (0.008%) and my Yamaha AVP (CX-A5100) is -90dB (0.003%).

The REAL question is, if I were to buy a new AVR or AVP today, would I buy one that has THD+N of 0.008%? My answer is YES because SINAD/THD+N is just one factor among many.

Would I buy the AVR if the THD+N is 0.01% (SINAD -80dB)? NO I would NOT.

I guess my personal standard is a SINAD of -82dB (0.008%) or better.

20 x Log (THD+N %) = SINAD

20 x Log (0.008%) =

20 x Log (0.00008) = -82dB (rounded up).

So I think the real question is, what is your personal SINAD/THD+N standard and what are the SALIENT factors in determining your purchasing decisions ?

In the case x3800 vs. x3700, we have THD+N of 0.001% vs. 0.004%.

So the question is, is the SINAD more important, or are the other features more important?

x3800:
1. 4 independent Sub EQ
2. Individual Preamp mode
3. Dirac firmware updates (additional fees)
4. More 8K HDMI

Only the buyer/owner can make that decision.

 

[ski2xblack]

Some ABX testing would dispel some golden ear delusions.

I would suggest that load invariance and adequate dynamic power are more significant. Audible differences between amps typically relates to their behavior when clipped and/or recovering from clipping conditions. These THD specs are the proverbial bee fart relative to the hurricane of distortion that speakers produce.

 

[Trell]

Some ABX testing would dispel some golden ear delusions.

I would suggest that load invariance and adequate dynamic power are more significant. Audible differences between amps typically relates to their behavior when clipped and/or recovering from clipping conditions. These THD specs are the proverbial bee fart relative to the hurricane of distortion that speakers produce.

THD, or THD+N for that matter, is one of a number of measurements to be taken into account, and not the only one.

As for noise vs THD there is this review&measurements by a ASR member Rja4000 with the following comment.

"Now we see the difference between aptX and SBC: The later seems to favor the noise reduction, while the former has lower distortion."

Fiio BTA30 Pro Bluetooth Transmitter and Receiver + DAC - Review

Hello Here is a review of a special device: This device is a Bluetooth Audio Transmitter, Receiver and DAC. This is the Fiio BTA30 Pro. The BTA30 Pro is about half the dimension of the (1U / half 19") RME ADI-2 Pro fs R in all directions: Half width, half height (without the antenna)...

www.audiosciencereview.com

 

[PENG]

Some ABX testing would dispel some golden ear delusions.

I would suggest that load invariance and adequate dynamic power are more significant. Audible differences between amps typically relates to their behavior when clipped and/or recovering from clipping conditions. These THD specs are the proverbial bee fart relative to the hurricane of distortion that speakers produce.

As mentioned, this poll is about bench test results, not just THD+N. I used THD+N as an example only.

 

[ski2xblack]

In that case, I guess I would give a nod of appreciation to the Buckeye amps. Nothing in Amirs tests is a deal breaker, IMO. They provide qualified power ratings all the way down to 2 ohms. I wouldn't perseverate on the bench tests THD results, even Amir admitted that it wouldn't be audible. i also appreciate their raw/basic diy aesthetic and value proposition. If I were in the market for an amp, they would likely be on the short list.

 

[lovinthehd]

First, while I read, I'd get that title corrected from "be" care....

 

[lovinthehd]

Now I might vote yes, but not for that particular reason. As to general use, it's limited but good to have is the way I look at it.

ps and my original impression is you were talking SINAD particularly rather than a full suite of bench tests results....

 

[}Fear_Inoculum{]

IM very limited and humble opinion, while I believe that testing is useful, it's not the deal breaker for myself. As stated, outside the audible spectrum, those measurements aren't terribly relevant. Good for determining whether the unit is well manufactured or not. But I look at the measurements (which I'm still learning about) to determine whether the cost/value ratio is there. A slightly worse measuring amp that provides as much, or more , power as I need for 1/3rd the cost? Sign me up.

 

[AcuDefTechGuy]

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?

 

[PENG]

First, while I read, I'd get that title corrected from "be" care....

Thank you, the "b" was supposed to be "w". I don't see a way to edit the title, so it will have to remain uncorrected. Unless one of the moderator can do it for me. Do you know of one that I can PM?

 

[Trell]

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?

For me it's not that quite straightforward and is on a case by case basis as a balancing act.

The device has to have features where some are required while others are more like nice to have. With features I also include connectivity, driver support (where applicable) and documentation.

For relevant measurements it should be at least good enough for the use case, whatever that may be, and preferably better than average. Say, if I use sensitive IEM I don't want a noisy headphone out, or have low-impedance difficult to drive speakers the amp must be able to power them cleanly to the loudness I require.

Warranty/Support/Reliability is important though reliability can be difficult evaluate. I don't import electronics from say, China, but buy locally in EU so that I'm covered by EU consumer laws.

Then there is price and I can be flexible there, but I don't have unlimited with money either. But for sure I can pay more for features I think I need or want, even though there are workarounds. I can pay more for better (perceived) quality, and even if it's manufactured in Europe or North America.

Brand as such is not that important to me other as a sign of excellent products.

 

[highfigh]

I don't want to hear noise and in 2022, we shouldn't hear any unless we're very close to the speakers which, unless people are having 1950s-1960s-style record listening parties, is unlikely.

My last integrated amp, which I recently sold because it's reaching the age of 'needs service, parts are hard to find', showed the following specs and a lt of new, more expensive equipment doesn't do this well, even though mine was made in 1989-

"Power output: 80 watts per channel into 8Ω (stereo)
Frequency response: 2Hz to 200kHz
Total harmonic distortion: 0.003%
Damping factor: 50
Input sensitivity: 0.17mV (MC), 2.5mV (MM), 150mV (line)
Signal to noise ratio: 68dB (MC), 86dB (MM), 105dB (line)
Output: 150mV (line)"

IM distortion is only slightly higher than THD, at .009% (4 Ohms), .008% (6 Ohms) and .008% (8 Ohms). Power bandwidth (IHF) 10-100KHz @ 4 or 8 Ohms, .002% THD.

Below the specs is a link to the service manual and it shows the rest of the specs-

Sony TA-F500ES Integrated Stereo Amplifier Manual | HiFi Engine

www.hifiengine.com

It was done before, it can be done now, without breaking the bank or troweling out BS about special sauces, cables/power cords or wiring schemes.

 

[highfigh]

For me it's not that quite straightforward and is on a case by case basis as a balancing act.

The device has to have features where some are required while others are more like nice to have. With features I also include connectivity, driver support (where applicable) and documentation.

For relevant measurements it should be at least good enough for the use case, whatever that may be, and preferably better than average. Say, if I use sensitive IEM I don't want a noisy headphone out, or have low-impedance difficult to drive speakers the amp must be able to power them cleanly to the loudness I require.

Warranty/Support/Reliability is important though reliability can be difficult evaluate. I don't import electronics from say, China, but buy locally in EU so that I'm covered by EU consumer laws.

Then there is price and I can be flexible there, but I don't have unlimited with money either. But for sure I can pay more for features I think I need or want, even though there are workarounds. I can pay more for better (perceived) quality, and even if it's manufactured in Europe or North America.

Brand as such is not that important to me other as a sign of excellent products.

I agree, especially about not buying directly from China (after a recent debacle). As far as brand, while it's not impossible for a major brand that's known for reliability to have a bad run, it's less likely than a company that doesn't sell as much, doesn't have the R&D budget to source better parts and doesn't have a long history. It's also possible that a component supplier might ship bad parts to a large number of other manufacturers who DID have a reputation for reliability and quality, as Samsung did before 2010 with their crappy capacitors. I believe they eventually settled, but they didn't even want to help customers of their own products when the TVs failed.

Lately, and it's mainly because I have worked for companies that sold AV equipment, reliability and parts availability are almost to me as important as sound/video quality- they can continue to cut their costs, but they really need to take a long, hard look at their QC and reliability. The problem: if they make products that can be serviced, they won't sell as many and that's where they make their money, not in providing service manuals, parts and training people to repair their products.

 

[PENG]

I don't want to hear noise and in 2022, we shouldn't hear any unless we're very close to the speakers which, unless people are having 1950s-1960s-style record listening parties, is unlikely.

My last integrated amp, which I recently sold because it's reaching the age of 'needs service, parts are hard to find', showed the following specs and a lt of new, more expensive equipment doesn't do this well, even though mine was made in 1989-

"Power output: 80 watts per channel into 8Ω (stereo)
Frequency response: 2Hz to 200kHz
Total harmonic distortion: 0.003%
Damping factor: 50
Input sensitivity: 0.17mV (MC), 2.5mV (MM), 150mV (line)
Signal to noise ratio: 68dB (MC), 86dB (MM), 105dB (line)
Output: 150mV (line)"

IM distortion is only slightly higher than THD, at .009% (4 Ohms), .008% (6 Ohms) and .008% (8 Ohms). Power bandwidth (IHF) 10-100KHz @ 4 or 8 Ohms, .002% THD.

Below the specs is a link to the service manual and it shows the rest of the specs-

Sony TA-F500ES Integrated Stereo Amplifier Manual | HiFi Engine

www.hifiengine.com

It was done before, it can be done now, without breaking the bank or troweling out BS about special sauces, cables/power cords or wiring schemes.

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.

 

[PENG]

Can anyone tell me how to contact a moderator to fix the typo in the title for me? Thank you.

 

[Trell]

Can anyone tell me how to contact a moderator to fix the typo in the title for me? Thank you.

You could try reporting your post and write the reason why.

 

[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 don't know why it would be difficult to look at THD and SNR- they're just two of the specs and if someone can't handle more than a few details,....

Both should be considered- stopping at either isn't the way a piece of equipment should be chosen.

The thing is, noise(hiss, especially) and THD are two different things- the noise usually comes from the components, not a distortion of the waveform by the circuit WRT input signal, levels, gain, etc. Some resistors are noisy, but they can perform well in other respects.

Hum is unacceptable, regardless of application. Often, a resistor value or quality/type adds hiss, hum is caused by bad filtering or poor rejection of EMI/RF and there's no excuse for either in modern equipment.

 

[highfigh]

Can anyone tell me how to contact a moderator to fix the typo in the title for me? Thank you.

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.