GR Research B24 AC Cord Review

[Lambda]

That graph showed mains interference which is pure tones.

My main interference is not pure tones. and they don't fall magically exactly in one FFT bin.

their noise still be inaudible

he GR research B24 is indeed less receptive to AC noise inducement.

noise != pure tones...

All I asked for was the reference as it's not on the graph.

The threshold of hearing is at around 0dbSPL so this defines the position of the green line to be at -120dB from the pure tone peak if the peak is per definition 120dbSPL.

But this is an electrical measurement not an acoustical. so the peak has a voltage level not an SPL level

We don't know the test voltage level.

To make the cable look worse just decrease the electrical signal defined as 120dbSPL by 30dBV and you get a 30dB worse SNR
To make the cable look better just increase the electrical signal defined as 120dbSPL by 30dBV and you get a 30dB better SNR

 

[pickyAudiophile]

Forgive me if the question has been answered already. About that ground plug, is it truely longer than described in NEMA 5-15 specification which is 21.4mm or 0.8425in (thx @DualTriode) at maximum? Just curious whether that's a "culpable" issue against Danny or not.

 

[DualTriode]

Forgive me if the question has been answered already. About that ground plug, is it truely longer than described in NEMA 5-15 specification which is 21.4mm or 0.544in at maximum? Just curious whether that's a "culpable" issue against Danny.View attachment 218656

Hello,
21.4mm / 25.4 mm/inch is equal to 0.8425 inches not 0.544 inch just incase someone measures it.

 

[Blumlein 88]

I apologize for trying to learn.

Any scientific paper I've ever read has had a References section. That's really handy for those, "hmmm... Where did this come from?" types of questions. But I guess those questions aren't welcome here. That's pretty sad actually.

Tom

He just told you, and not for the first time in this thread where his References come from. Are you incapable of understanding that. His explanation is about as simple as it can be, and one has to think you are being intentionally problematic and not from lack of understanding.

 

[DualTriode]

He just told you, and not for the first time in this thread where his References come from. Are you incapable of understanding that. His explanation is about as simple as it can be, and one has to think you are being intentionally problematic and not from lack of understanding.

More insults.

 

[Blumlein 88]

Hello All,

The “Threshold of hearing Curve” crosses 1000Hz at 0 SPL.

The Threshold of Hearing is often stated as 0 SPL. (A relative dB scale)

The “Threshold of Hearing” needs a closer examination. The TH was empirically measures in a dead quiet space. The typically quiet listening room will have a SPL somewhere in the 40dB SPL range. Tones that are well above the TH will be masked and not audible in the typical listening room.

“Threshold of Hearing” and audibility are two different things.

The graphic uses an arbitrary dBrA scale that places ~3kHz at -120dBrA’s. By looking at the face of the graphic the -120dBrA appears to be picked from the sky without explanation and treated as thou shalt not ask without fear of being insulted. I believe that the dBrA scale is confusing to most readers.

Placing the “Threshold of Hearing Curve” on top of a FFT requires much more explanation if Engineers are labeled “confused” by what it is trying to communicate.

Just my opinion

DTView attachment 218650

So your complaint is the room isn't quiet. The threshold of hearing on the graph applies to a quiet room. In a quiet room the artifacts shown are below being heard. So one can reasonably expect the same level of artifacts in a noisy room are even further from audibility. The expectation is the graph will be amplified and fed to a suitable speaker able to play at 120 db SPL. One is ignoring distortion in the speaker and noise in the room. None of which improve audibility. So the low level artifacts are below thresholds in perfect conditions and even more so in noisy or slightly distorted positions. And I don't believe you failed to understand that.

 

[Blumlein 88]

More insults.

Do you want a link to the Fielder papers? Is that what would make you happy? He has provided it at least once. I could did up for you again.

 

[Lambda]

He just told you, and not for the first time in this thread where his References come from.

They/He/You seam to misunderstand the question
No one is "questioning" Fletcher-Munsons work.

The way it is used here is "unconventional"
The electrical signal is per definition and as mentioned in the screenshot equivalent to 120dBSPL.

But every signal can be defined as 120dBSPL.
+40dBV signal can be defined/(amplified) to 120dBSPL. but so can a -40dBV signal

If the electrical signal defined as 120dBSPL would be 30dBV lower then the unspecified arbitrary chosen level we don’t know it would look like this

If the signal would be 20dBV higher:

The measurements don’t show/tell the same sorry?!
this is why absolute dBV are important to be mentioned

 

[DualTriode]

Do you want a link to the Fielder papers? Is that what would make you happy? He has provided it at least once. I could did up for you again.

Have you paid your $33.00 each to download the Fielder paper(s)?

I am an AES member and have read the referenced papers.

What I find interesting is that none of the sound level graphs have a scale labeled dBrA. dBrA is taken from the sky and does not mean anything without an explanation. dBrA is internal Audio Precision terminology.

Every graph in the Fielder paper has sound levels with a dB SPL scale as is used in every text book on the subject and has inherent common meaning.

Thanks DT

 

[LTig]

They/He/You seam to misunderstand the question
No one is "questioning" Fletcher-Munsons work.

The way it is used here is "unconventional"
The electrical signal is per definition and as mentioned in the screenshot equivalent to 120dBSPL.

But every signal can be defined as 120dBSPL.
+40dBV signal can be defined/(amplified) to 120dBSPL. but so can a -40dBV signal

If the electrical signal defined as 120dBSPL would be 30dBV lower then the unspecified arbitrary chosen level we don’t know it would look like this
View attachment 218664
If the signal would be 20dBV higher:
View attachment 218669

The measurements don’t show/tell the same sorry?!
this is why absolute dBV are important to be mentioned

Your artificial changes of the peak heigth forgot to raise the noise floor and the distortion peaks accordingly. You've manipulated the measurement data hence your conclusions are wrong.

I try to explain it my way.

The red curve is the measurement of the output of the APX fed through the power cables used as interconnect. The level of the test signal is referenced to 0 dBrA at 1kHz so that one can directly read the level of the distortion components.

The point to understand is this: if you now connect this signal not back to the APXs input but to a power amp with a speaker, and you set the volume of the power amp such that the 1 kHz is played back at 120 dB SPL, then the 0 dBrA reference point represents 120 dB SPL. Just imagine a second scale ruler with 120 dB SPL at 0 dBrA, 110 dB SPL at -10 dBrA, and so on. This allows to add the threshold of hearing accordingly. (EDIT: that's the power of working in dB: complicated mulitiplications and divisions become simple additions and subtractions.)

This is the case for ideal conditions (dead silent room, perfect power amplifier, perfect speaker). In the real world the threshold of hearing will be higher, so the chance for a human being to hear a difference becomes smaller yet.

Hope it helps.

 

[Kevinfc]

A lot of time I feel like we’re just beating a dead horse. Maybe it needs to be written again and again for the new readers who venture in, but when certain items are reviewed does anyone expect to be surprised ?
Got it, short of some functional issues, cables are cables. Line filters are a complete waste and on and on. I’d rather read about the spectacular new products that are coming out so rapidly these days. Just me.

 

[DualTriode]

So your complaint is the room isn't quiet. The threshold of hearing on the graph applies to a quiet room. In a quiet room the artifacts shown are below being heard. So one can reasonably expect the same level of artifacts in a noisy room are even further from audibility. The expectation is the graph will be amplified and fed to a suitable speaker able to play at 120 db SPL. One is ignoring distortion in the speaker and noise in the room. None of which improve audibility. So the low level artifacts are below thresholds in perfect conditions and even more so in noisy or slightly distorted positions. And I don't believe you failed to understand that.

You are making up words that I did not say.

The FFT plot is clearly an electrical measurement measured in dBV or volts.

The Threshold of Hearing is an acoustical measurement measured in dB SPL. Measured at some other place and time or domain. They were not appended measurements. AP does provide APx500 acoustical measurement software at an additional price.

dBrA is a false or made up equivalency, at best a vague conceptual comparison. Kind of an if, then comparison graphic.

Much like confusing speed and distance.

Thanks DT

 

[Lambda]

The red curve is the measurement of the output of the APX fed through the power cables used as interconnect. The level of the test signal is referenced to 0 dB at 1kHz so that one can directly read the level of the distortion components.

i understand that...
but i don't care about distortion components because cable don't add distortion.
if it would the distortion components would be hiding behind the noise.
And at this low level its not clear if/what distortion is coming from the analyzer.

this test is suposed to show inductive noise pickup from a transformer

The level of the test signal is referenced to 0 dB

actually the scale is referenced to the test signal and not the other way around.
What ever the peak is,is defined as 0dBrA but we don't now the actual amplitude.

The point to understand is this: if you now connect this signal not back to the APXs input but to a power amp with a speaker, and you set the volume of the power amp such that the 1 kHz is played back at 120 dB SPL, then the 0dB reference point represents 120dB SPL. This allows to add the threshold of hearing accordingly.

i also understand this...

Try to reed my post again.
A low signal would need more "gain" to play back at 120 dB SPL
more "gain" would amplify the noise also more therefore a lower signal has worse signal to noise ratio.

this would look like this:

This is the case for ideal conditions (dead silent room, perfect power amplifier, perfect speaker). In the real world the threshold of hearing will be higher, so the chance for a human being to hear a difference becomes smaller yet.

this is not my(the) point

Your artificial changes of the peak heigth

to simulate a lower or stronger electrical test signal.

forgot to raise the noise floor and the distortion peaks accordingly.

i did not forgot! this is intentional. this is the point.
the electrical noise would not change if the electrical input test signal would be changed in amplitude.
But the Acustic noise would change because the "gain" would need to be changed so it plays back at the same 120dBSPL

 

[Doodski]

A lot of time I feel like we’re just beating a dead horse. Maybe it needs to be written again and again for the new readers who venture in, but when certain items are reviewed does anyone expect to be surprised ?
Got it, short of some functional issues, cables are cables. Line filters are a complete waste and on and on. I’d rather read about the spectacular new products that are coming out so rapidly these days. Just me.

Some pesky animals need to be put to down per say to protect the masses. I dare say I enjoyed putting a bullet (22 long.) into one nasty cow's skull that attempted to disembowel me in the soft stomach area. The snake oil keeps a flowing and the easily accessible suckers keep coming to buy the stuff. I am happy each time a new review comes out that debunks snake oil product. The industry as I see it has been waiting a long while for the @amirm sort of peeps to come along and dish out the retribution!

 

[Newman]

For example, you often hear a person say "I didn't expect to hear any difference but I did!" Clearly no expectation bias there. This actually happens to me at shows all the time.

That’s not how it works, Amir. It is a predominantly unconscious perception mechanism, and conscious expectation is a bit player. So the quote above means nothing in terms of absence of expectation bias.

Cheers

 

[Andysu]

Some pesky animals need to be put to down per say to protect the masses. I dare say I enjoyed putting a bullet (22 long.) into one nasty cow's skull that attempted to disembowel me in the soft stomach area. The snake oil keeps a flowing and the easily accessible suckers keep coming to buy the stuff. I am happy each time a new review comes out that debunks snake oil product. The industry as I see it has been waiting a long while for the @amirm sort of peeps to come along and dish out the retribution!

that , you need a cool drink . that was so morbid reading . poor cow and beating a horse ? i think why not beating a bose speaker for now okay everyone . it's like "beating a knackered bose speaker" at least that is immaterial objevt not some lovely animal creature .

"beating a knacakred bose speaker".

 

[Doodski]

that , you need a cool drink . that was so morbid reading . poor cow and beating a horse ? i think why not beating a bose speaker for now okay everyone . it's like "beating a knackered bose speaker" at least that is immaterial objevt not some lovely animal creature .

"beating a knacakred bose speaker".
View attachment 218680

If you met, "BOSS" the huge round bad tempered beasty animal that attempted goring me while I kindly fed it fresh cut green grass in the pasture you would maybe feel the same way. Think like hippopotamus violence stuff. It was a very violent aggressive animal and tried to kill me for not feeding her fast enough. We had one named Betsy after and she came with instructions to let her a have a long good life and we passed on the same. Lovely creature. She looked like a baby deer that was huge.

 

[GradyBeach247]

Oh, and I know this has been forgotten in this review. Anyone who knows anything about plugs knows you just cut off that hard to plug in ground connector and voila! you have a nice easy to insert high performance power cable. To do it right, make sure you cut the ground pin off both ends. UL will not mind as they haven't seen the cable. Good friends teach their friends to get rid of all grounding plu

gs on all wires, they just get in the way of lifting more veils and really opening up the music. At least that is what I heard on a subjectivists site, too much noise, static and hiss coming from the evil ground pins!

For easier insertion, the cable foreskin needs to be removed

 

[amirm]

The typically quiet listening room will have a SPL somewhere in the 40dB SPL range.

It does not. Never has, never will. I explained this in my article. How could you continue to disregard information put in front if you? Room noise has a frequency dependent SPL. There is no such one number for it.

 

[Blumlein 88]

They/He/You seam to misunderstand the question
No one is "questioning" Fletcher-Munsons work.

The way it is used here is "unconventional"
The electrical signal is per definition and as mentioned in the screenshot equivalent to 120dBSPL.

But every signal can be defined as 120dBSPL.
+40dBV signal can be defined/(amplified) to 120dBSPL. but so can a -40dBV signal

If the electrical signal defined as 120dBSPL would be 30dBV lower then the unspecified arbitrary chosen level we don’t know it would look like this
View attachment 218664
If the signal would be 20dBV higher:
View attachment 218669

The measurements don’t show/tell the same sorry?!
this is why absolute dBV are important to be mentioned

So the AP unit Amir uses has a max balanced output of 26.66 volts rms. Let us say he used that. Agreed it would have been good to know what level the signal was. Let us say we drop that by 20 db which is now 2.67 volts. None of what is left in the GRR cable assuming those levels are unchanged reach the F-M curve. Neither do the levels of the generic cable. So that is the worst way this could have been represented. The conclusion doesn't change.