Standards for Audio Electronics Measurements?

[amirm]

So I keep running into companies who send me products with best intentions but miss key aspects that cause me to not recommend. And example is a very nice dongle I recently received that had balanced output but was limited to just 2 volts out. If you don't know, I like to see minimum of 4 volts out from such a port as otherwise, you can find unbalanced dongles at lower cost that do that.

Another example is channel balance issue with had with an AIYIMA amp where there was almost 1 dB differential.

Yet another is expected SINAD for an amplifier. Yes, we don't rate amps on that one number but if SINAD is say, 60 dB, the rest are going to follow.

In many cases decision makers are not knowledgeable in these companies so proudly show me the gear, only then realizing they could have built something better, but didn't.

Note that my focus here is for electronics only. And I am thinking about the fewest key criteria that passes the "acceptable" mark from me, and by implication, from you all. They can do better of course to get higher praise but want to establish what we like to see.

An example for a dongle:

Output voltage: at least 2 volts on unbalanced, 4 volts on balanced.
SINAD: 100 dB or better, 1 kHz, 22.4 kHz bandwidth
SNR at 50mv: 85 dB (?)
SNR at full 2/4 volt output: 110 dB (?)
Output impedance < 1 ohm

Example for Amplifier:
SINAD >= 80 dB
SNR >= 110 dB (?)
Channel balance < 0.5 dB
Crosstalk > 70 dB @20 kHz


This would be presented as general guidelines for companies to adopt (or not). The point of this thread is not to discuss the specifics although you can, but determine if it is time for us to do this. Hate to have companies ready to produce performant products based on objective measurements but not know clearly what those measurements should be.

What say you?

 

[amirm]

Adding on, I could also publish AP project files for each specific measurement.

 

[AdamG]

Maybe promote to front page and get some input from our resident Builders and Designers. Good idea Amir.

 

[beeface]

Sounds like a good idea. I think that having a product that is ASR xxxx Certified could even become a marketable feature.

Manufacturers could get their product officially certified for a fee.

Since ASR is not-for-profit, maybe this would be a good way to keep money coming in.

 

[CleanSound]

Not exactly sure if I understand this post. Are you asking ASR members to recommend what the minimum passing mark ought to be for manufacturers to aspire to?

 

[pablolie]

I think it would be absolutely awesome to converge on a number of limited , clearly defined measurements that are consistently applied to be compliant with a basic HiFi compliance standard. It has been missing in the industry.

Driving an IEEE or such standard is mission impossible, and the few existing ones (I recall EN 6000ish) are meh and not binding. A certification body would be great.

 

[beeface]

The consumer audio landscape does seem like the wild west, and it would be nice to see it standardised to allow products from different manufacturers to be interoperable without worrying about compatibility.

With that said, I'm no engineer, so as a layman, the "why" is one thing that's a bit of a mystery to me. How does one decide what the minimum spec value should be?

For example:

And example is a very nice dongle I recently received that had balanced output but was limited to just 2 volts out. If you don't know, I like to see minimum of 4 volts out from such a port as otherwise, you can find unbalanced dongles at lower cost that do that.

Why isn't 2 volts sufficient for this purpose? Why is 4 volts considered an ideal minimum - why not 3v or 5v? Genuinely curious - I have no idea!

 

[MC_RME]

Output voltage: at least 2 volts on unbalanced, 4 volts on unbalanced.

Balanced.

 

[MC_RME]

The consumer audio landscape does seem like the wild west, and it would be nice to see it standardised to allow products from different manufacturers to be interoperable without worrying about compatibility.

With that said, I'm no engineer, so as a layman, the "why" is one thing that's a bit of a mystery to me. How does one decide what the minimum spec value should be?

For example:



Why isn't 2 volts sufficient for this purpose? Why is 4 volts considered an ideal minimum - why not 3v or 5v? Genuinely curious - I have no idea!

Balanced automatically gives you double the output voltage. If it's below 4 V the circuit either has a problem, or unbalanced also is below 2 V - so requirement not met.

 

[pablolie]

Why isn't 2 volts sufficient for this purpose? Why is 4 volts considered an ideal minimum - why not 3v or 5v? Genuinely curious - I have no idea!

I agree there is a bizarre disconnect between preamp power requirements and the +200W amplifiers we are demanded to yearn for. The mismatch is quite comical. When I owned top rated DAC/preamp and poweramp from the same brand (both recommended here), the volume in the preamp never went past 25%. And that was after setting stuff to a non recommended -20dB or so of attenuation.

 

[Somafunk]

A balanced output also gives less THD and avoids crosstalk

 

[amirm]

Not exactly sure if I understand this post. Are you asking ASR members to recommend what the minimum passing mark ought to be for manufacturers to aspire to?

No, I am asking if we should announce what our expectations are with respect to measured performance. What those specs are would be the second phase after we answer that question.

 

[pablolie]

A balanced output also gives less THD and avoids crosstalk

Only relevant over longer distances though.

 

[Philbo King]

So I keep running into companies who send me products with best intentions but miss key aspects that cause me to not recommend. And example is a very nice dongle I recently received that had balanced output but was limited to just 2 volts out. If you don't know, I like to see minimum of 4 volts out from such a port as otherwise, you can find unbalanced dongles at lower cost that do that.

Another example is channel balance issue with had with an AIYIMA amp where there was almost 1 dB differential.

Yet another is expected SINAD for an amplifier. Yes, we don't rate amps on that one number but if SINAD is say, 60 dB, the rest are going to follow.

In many cases decision makers are not knowledgeable in these companies so proudly show me the gear, only then realizing they could have built something better, but didn't.

Note that my focus here is for electronics only. And I am thinking about the fewest key criteria that passes the "acceptable" mark from me, and by implication, from you all. They can do better of course to get higher praise but want to establish what we like to see.

An example for a dongle:

Output voltage: at least 2 volts on unbalanced, 4 volts on unbalanced.
SINAD: 100 dB or better, 1 kHz, 22.4 kHz bandwidth
SNR at 50mv: 85 dB (?)
SNR at full 2/4 volt output: 110 dB (?)
Output impedance < 1 ohm

Example for Amplifier:
SINAD >= 80 dB
SNR >= 110 dB (?)
Channel balance < 0.5 dB
Crosstalk > 70 dB @20 kHz


This would be presented as general guidelines for companies to adopt (or not). The point of this thread is not to discuss the specifics although you can, but determine if it is time for us to do this. Hate to have companies ready to produce performant products based on objective measurements but not know clearly what those measurements should be.

What say you?

It would also be great if freq response was specified at -3 dB points and amp power was in sustained RMS, though the marketing folks might go epileptic at the thought.

 

[wwenze]

Getting Redbook 2Vrms out from a dongle requires additional circuit to generate voltage from the 5V supply... So that hurts price/performance. The Apple dongle outputs 1Vrms for example.

 

[amirm]

Sounds like a good idea. I think that having a product that is ASR xxxx Certified could even become a marketable feature.

That is a related but different thing. A certification would be much more involved than this simple list of minimum performance criteria.

 

[amirm]

Getting Redbook 2Vrms out from a dongle requires additional circuit to generate voltage from the 5V supply... So that hurts price/performance. The Apple dongle outputs 1Vrms for example.

Which is the reason to expect 2 volts when you can get 1 volt for $9 and you charge $50 for this dongle.

 

[amirm]

Why isn't 2 volts sufficient for this purpose? Why is 4 volts considered an ideal minimum - why not 3v or 5v? Genuinely curious - I have no idea!

The requirement comes from the point of view of driving high impedance headphones. Highly popular headphones have 300 ohm impedance. Divide 1 volt by 300 and you get so little power to drive them. Go to 2 volts and now you have much healthier level of power. 4 volts becomes even nicer and is the differential version of 2 volts.

 

[phoenixdogfan]

Perhaps there should be something like a Panther with missing limbs to indicate, for example, when a product fails to meet minimum expected standards, like 4 VRMS for balanced outputs.

 

[NTK]

An example for a dongle:

Output voltage: at least 2 volts on unbalanced, 4 volts on balanced.
...

I think 4 V output (= 53 mW into 300 ohms) is quite rare for dongles. Some of the recommended ones here fell short of it.