Impact of AC Distortion & Noise on Audio Equipment

[IVX]

Actually, my AC regenerator story proofs that this class of equipment wouldn't sell as noname, only as a known brand(even if it is stupid AB amp+trafo for $5000). Chinese tried to offer my design to some OEM customers and no one had an interest. Finally, $100000 they paid was simply lost. AC regenerator is the thing that pretty much nobody needs for free

 

[JohnYang1997]

Again, I'm going to make the argument that you're using three devices to represent the entire consumer audio industry. None of those devices are ones that I'd be particularly concerned about having issues. You're an engineer. You should know that three examples of not exhibiting an issue does NOT prove that the issue doesn't exist.

In fact, there's a damn good chance all three devices you used have REGULATED power supplies. That is far from being the case with all equipment.

-Lots of tube equipment still uses AC for the filaments, and there is (in many cases) good reason for that.
-Lots of solid-state power amplifiers have unregulated linear power supplies
-Lots of tube equipment, especially older equipment, uses unregulated power supplies due to the cost and general PITA of designing a high voltage regulated supply.
-There are plenty of class A amplifier stages that don't use any feedback and have a lousy PSRR.
-A really bad situation might be a piece of tube equipment that uses an unregulated power supply and uses an AC filament supply.
-Lots of people still use legacy equipment, whether you like it or not.
-Lots of people use boutique equipment that isn't up to ASR standards, whether you like it or not.

Again, I am ABSOLUTELY NOT saying that people should be buying $3000 power conditioners. In fact, I don't think anyone is saying that. What some of us are saying, however, is that the tests performed are not sufficient to back up the conclusions that were drawn. I don't care if you're trying to do a service (stopping people from wasting money), insufficient data to support conclusions is a problem that casts doubt on the credibility of the author.

Regenerators ONLY gives a standard voltage level AC output. It does NOT improve the powered devices in any other way.
Simple example: Many homes have higher than standard voltage, eg 234V vs 220V or 113V vs 110V. Using regenerator does not provides ANY improvement for these situations.
Trying to improve this little amount of power makes no sense when you can just buy a much better performing device for the price of the regenerator.

 

[Headchef]

no
Proper solution: get an amplifier with more power.

that approach might suit manufacturers supplying such things but my amp is as follows:

EAR / Yoshino 859

true Class A design, 13W per channel, both channels driven and over a power bandwidth of 20Hz to 20kHz +/- 0.5dB. Frequency response is 5Hz to 50kHz for 1W output, sensitivity for full power is 200mV, and distortion at full power is <2% at lkhz and <5% from 20Hz to 20kHz

I certainly don’t need “more power”, however adding a stabilised power supply has noticeably improved the sound throughout the day rather than it only “sounding at its best” when everything else is powered down.

As I mentioned previously our old property has a lot of commercial refrigeration etc and subsequently there are noticeable variations in our mains supply, to rewire the grade 2 listed 4 floor building would cost a king’s ransom where as a £600 box to provide a stable supply and protection to my amplifier (insurance replacement value £4600) seems a sensible application of such a fondly derided yet useful technology.

Now Amir clearly stated that peak power may be reduced due to voltage sag, and as such it’s logical to conclude that stabilising the power will (and does) result in an improvement in stability and performance.

thanks but the suggestion to buy a more powerful amplifier is as ridiculous as many of the claims made by the snake oil peddlers.

 

[IVX]

wwenze, this is could be not so plain as we want to. Some of amps may produce an ugly clipping with some ringing and so on(BTW, popular Chinese opamp RT6883=SGM8261 for example has such ugly clipping, that makes easy noticeable very lite clipping). 30V vs 33V rail voltage may have or have no clipping. However, as I did say already, people like to have 24/96 at least with the difference vs 16/44.1 a lot less than 1db. So what we can say them?

 

[JohnYang1997]

that approach might suit manufacturers supplying such things but my amp is as follows:

EAR / Yoshino 859

true Class A design, 13W per channel, both channels driven and over a power bandwidth of 20Hz to 20kHz +/- 0.5dB. Frequency response is 5Hz to 50kHz for 1W output, sensitivity for full power is 200mV, and distortion at full power is <2% at lkhz and <5% from 20Hz to 20kHz

I certainly don’t need “more power”, however adding a stabilised power supply has noticeably improved the sound.

As I mentioned previously our old property has a lot of commercial refrigeration etc and subsequently there are noticeable variations in our mains supply, to rewire the grade 2 listed 4 floor building would cost a king’s ransom where as a £600 box to provide a stable supply and protection to my amplifier (insurance replacement value £4600) seems a sensible application of such a fondly derided yet useful technology.

Now Amir clearly stated that peak power may be reduced due to voltage sag, and as such it’s logical to conclude that stabilising the power will (and does) result in an improvement in stability and performance.

thanks but the suggestion to buy a more powerful amplifier is as ridiculous as many of the claims made by the snake oil peddlers.

You either don't need both or you need a more powerful amplifier. Simple as that.
No performance or stability will be improved. None.

 

[JohnYang1997]

wwenze, this is could be not so plain as we want to. Some of amps may produce an ugly clipping with some ringing and so on(BTW, popular Chinese opamp RT6883=SGM8261 for example has such ugly clipping, that makes easy noticeable very lite clipping). 30V vs 33V rail voltage may have or have no clipping. However, as I did say already, people like to have 24/96 at least with the difference vs 16/44.1 a lot less than 1db. So what we can say them?

It can also be the difference of operating normally or simply destroyed.

 

[jasonhanjk]

You either don't need both or you need a more powerful amplifier. Simple as that.
No performance or stability will be improved. None.

Maybe he can simply improve the supply by adding $100 worth of cap at the amps DC supply.

 

[JohnYang1997]

Maybe he can simply improve the supply by adding $100 worth of cap at the amps DC supply.

Yes, you can.

 

[wwenze]

Surely if, as you say, peak power availability may be reduced due to voltage sag, then by adding a device to provide a consistent power feed is going to ensure that there are no adverse effects due to fluctuations?

it seems to make logical sense that the removal of power supply fluctuations would be a sensible thing to do, as it would ensure that a system would be devoid of fluctuations, optimal operation no?

AC voltage *is* fluctuating. At 60Hz.

Filters remove any frequency component starting from at least a few harmonics higher. But it must do nothing to 60Hz. Otherwise it will change that AC voltage into DC voltage.

Overvoltage / undervoltage conditions that last more than a few cycles have frequency component LOWER than 60Hz. And yes, there ARE filters / regulators / solutions that can resist changes in these lower frequency components but do not affect 60Hz. Flywheel is one common mechanical method of regulating your mains voltage transmission, and there are other magnetic (transformer) and electronic methods. (Regenerator)

 

[DSJR]

These are what I've used on the digital gear here (most quite old and before EU? legislation I believe).

https://uk.farnell.com/roxburgh/pmf...PING-SMART-PASSIVES-Test726&gross_price=true#


Not sure anything is touched at 'audio' frequencies though. [EDIT - I meant mains supply audio frequency harmonics, not music signals...]

When I lived in Bedfordshire (UK), the mains seemed to be much worse on some days than others (repeatable back then and not sure if it was my mood or real - wasn't just me who noticed this though). Of course back then, no measurements taken of line voltage or distortion on the line. It was here I was told about the possible benefits of cable ferrites, so maybe there was a lot of rf type rubbish coming through?

 

[Headchef]

You either don't need both or you need a more powerful amplifier. Simple as that.
No performance or stability will be improved. None.

so are you saying that the only solution to “peak power availability may be reduced due to voltage sag” is to just buy a more powerful amp?

 

[JohnYang1997]

so are you saying that the only solution to “peak power availability may be reduced due to voltage sag” is to just buy a more powerful amp?

If you want to interpret like that, yes. But it's more like the only effective solution is to buy a more powerful amp. There's no such thing as you need just the little more power from the regenerator. No, you simply don't need that.

 

[don'ttrustauthority]

You know, it might be interesting to compare if the different tubes themselves change the way the amplifier (or dac in this case) measures. If you go to upscale audio dot com they sell tubes well over $100.

 

[Headchef]

If you want to interpret like that, yes. But it's more like the only effective solution is to buy a more powerful amp. There's no such thing as you need just the little more power from the regenerator. No, you simply don't need that.

i’m not quite sure I follow you, my point is that my main power is inherently fluctuating due to it only being single phase and having to power a restaurant, actually I’d forgotten to include the bar and a few other bits, so the devices with our building are as follows:

x5 commercial fridge units (kitchen)
x1 steriliser (kitchen)
x2 robot coupe food processors
x2 blenders
x1 plate warmer
x1 electric salamander
x1 commercial extraction
x1 air intake
x1 insectocuter
2x commercial bar fridges
1x glass washer
1x ice machine
1x Faema 2gang coffee machine
1x burr grinder
1x 3 floor dumb waiter (lift)
1x deep freezer
1x domestic fridge
1x lg 8kg washing machine

all of which are used throughout the day. Now I’m pretty sure that is well outside normal domestic loading and there’s no doubt that these items all cause the power to fluctuate wildly (I have an extension cable which has a light that I can watch flickering like a candle even with nothing connected to it!). I’m not quite sure what kind of amplifier could operate with no effects from such a scenario but if you could recommend one I’d happily demo it A/B (blind testing) to see if it sounds superior to what I have now which in an EAR/Yoshino 859 connected to a Keces BP-600. If it’s better, I’ll buy it!

 

[David_M]

Common mode chokes are very common in electronics (usually there for regulatory reasons). In addition, your output, i.e. the speaker, is a differential load. It doesn't care what the signals on the speaker cable are doing relative to safety ground. And of course use of balanced interconnects helps a lot in impact of common-mode noise.

Is there a scenario I am not addressing here?

Yes, but a great majority of receiver or low and high-end power amp outputs to speakers are NOT balanced, but single-ended. Hence the (-) terminal of the speaker is grounded, hence not a differential load anymore.

 

[Helicopter]

Even if you do have something with audible mains coming into the signal path, when you measure SINAD, the contribution of the sine wave is going to be 98%+ of the mains noise, and mains distortion and dirtiness is going to be <2% of what is bleeding into the signal. If you filter out a sine wave from the signal path, you almost inevitably will filter the dirtiness far lower. So it really doesn't matter if the mains is clean or dirty.

Take a tube amp with AC heater. You are going to get some mains coming from the plate. Whether that mains is 98% sine wave or 100% pure sine wave is not going to change the level of mains noise in any important way. It is not like negative feedback is a pure sine wave that will null the primary mains frequency component in the signal and leave the dirt behind.

Am I missing something?

Edit: 98%/2% not 99%/1%

 

[diddley]

Thanks Amir great lesson and debunk.

 

[solderdude]

These are what I've used on the digital gear here (most quite old and before EU? legislation I believe).

https://uk.farnell.com/roxburgh/pmf...PING-SMART-PASSIVES-Test726&gross_price=true#


Not sure anything is touched at 'audio' frequencies though.

When I lived in Bedfordshire (UK), the mains seemed to be much worse on some days than others (repeatable back then and not sure if it was my mood or real - wasn't just me who noticed this though). Of course back then, no measurements taken of line voltage or distortion on the line. It was here I was told about the possible benefits of cable ferrites, so maybe there was a lot of rf type rubbish coming through?

These just start to do something above the audible range and only for the mains frequencies. There is NO audio passing through these filters.
Just short current pulses.

Ferrites are intended to do something in the MHz range.

 

[solderdude]

i’m not quite sure I follow you, my point is that my main power is inherently fluctuating due to it only being single phase and having to power a restaurant, actually I’d forgotten to include the bar and a few other bits, so the devices with our building are as follows:

x5 commercial fridge units (kitchen)
x1 steriliser (kitchen)
x2 robot coupe food processors
x2 blenders
x1 plate warmer
x1 electric salamander
x1 commercial extraction
x1 air intake
x1 insectocuter
2x commercial bar fridges
1x glass washer
1x ice machine
1x Faema 2gang coffee machine
1x burr grinder
1x 3 floor dumb waiter (lift)
1x deep freezer
1x domestic fridge
1x lg 8kg washing machine

all of which are used throughout the day. Now I’m pretty sure that is well outside normal domestic loading and there’s no doubt that these items all cause the power to fluctuate wildly (I have an extension cable which has a light that I can watch flickering like a candle even with nothing connected to it!). I’m not quite sure what kind of amplifier could operate with no effects from such a scenario but if you could recommend one I’d happily demo it A/B (blind testing) to see if it sounds superior to what I have now which in an EAR/Yoshino 859 connected to a Keces BP-600. If it’s better, I’ll buy it!

You forgot to mention the countless other business and domestic appliances of everyone else connected to the same street transformer.

Any decent SMPS should work just fine. The few motors starting and stopping should have it's own capacitors or other countermeasures IF it complies to certain FCC rules. There is a chance some of the peaks may make it into the amp or become common mode which may become audible.

By the way... this is a much bigger issue for 115V systems than for 230V systems.

 

[solderdude]

Yes, but a great majority of receiver or low and high-end power amp outputs to speakers are NOT balanced, but single-ended. Hence the (-) terminal of the speaker is grounded, hence not a differential load anymore.

From the speaker's viewpoint it does not matter if a SE or balanced output is connected. The speaker does not care if one connector is tied to (signal)ground or not. Across the speaker terminals there is just a signal. The output resistance of the amp is low and voltage levels are high.