Amplifiers affecting speaker frequency response - Page 7 - AVS Forum
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Audio Theory, Setup, and Chat > Amplifiers affecting speaker frequency response
arnyk's Avatar arnyk 01:36 PM 11-14-2013
Quote:
Originally Posted by OllieS View Post

Quote:
Originally Posted by amirm 
I have the paper and read it a number of times. The paper is a "meta analysis" in that it presents no new research. But rather attempts to draw conclusions based on formal and informal tests done by others. This is from the intro of the paper:

Okay, so there is no in-depth information surrounding the testing itself, as in how the tests were conducted or any test protocols - only the results of the testing are known and published.

Would you say that is sufficient to draw a conclusion of global significance?

It is only necessary to go into all of the details about how each test was done if every test was done in a different way. These tests were all level-matched, time-synched, quick-switched under listener control, ABX tests.

mcnarus's Avatar mcnarus 01:42 PM 11-14-2013
Quote:
It is great that you have done your own testing. But as far as I know, Arny does not at all value single blind tests. So if you agree with him, you need to dismiss the results of your own tests .
Um, no. Single-blind tests that produce positive results are open to the criticism that the administrator(s) inadvertently tipped off the subject(s). But single-blind tests with negative results do not suffer the same flaw.

Lest you think that unfair, it works in the other direction, too. A negative test that didn't allow quick switching is open to the criticism that better test protocol might have produced a different result. But if you can hear a difference reliably without quick switching, you will certainly be able to with it.
mcnarus's Avatar mcnarus 01:44 PM 11-14-2013
Quote:
You sent me an AES link. What am I supposed to do with that?
Click on it.

Sheesh.
67jason's Avatar 67jason 01:48 PM 11-14-2013
Quote:
Originally Posted by amirm View Post

Quote:
Originally Posted by 67jason View Post

When first learned about the concepts being discussed here I was unsure of their validity and correctness. You know what I did? I spent hours upon hours researching abx, ab, and dbt tests, both audio related and otherwise. I learned a lot. I then, to the best of my ability performed my single blind test in my own home using a respected stereo receiver, 2 respected avr's and a respected power amp. All using the same source and material, level matched to the best of my ability. Ya know what I discovered? Yup that's right, these guys here like arnyk, kbarnes, and dozens of others were right.
It is great that you have done your own testing. But as far as I know, Arny does not at all value single blind tests. So if you agree with him, you need to dismiss the results of your own tests smile.gif. If you do believe in value of single blind tests, there are indeed formal ones that dispute the position of the people you list. That data has been presented in this forum numerous times. Surprised that your research did not land on them.

I also see nothing in your research with regards to what we are asking the opposition to do: read AES articles. How many articles did you buy and read there?
I'm well aware of where single blind tests fall into the scheme of things. I don't need you to educate me on the fact that arnyk has issues with them, nor that they are not the absolute best methodology to use. I did the best that I could with my own resources. My results were my own and were enough to satisfy my need to know weather or not the concepts as ofteoften discussed on avs, of what can and what can't constitute an audible difference amongs receiver, amps and avrs, as well as sources such as shiny disc players.

What does it matter how many papers I got from aes? Is it an ego thing? The more I obtained the more credible I am? Is that it?

I am very familiar with you posting style and how you don't take well to being wrong and how you will nitpick the minutiae in all posts you dont like, as well as your need to continue to drag out arguments. Feel free to pick my posts and my conclusions apart if you wish, it won't change the laws of physics, nor will it change what I have learned for myself to this point, nor what I may continue to learn in the future.

The fact of the matter is I took the time to research and learned a thing or two in the process and will continue to do so.
mcnarus's Avatar mcnarus 01:59 PM 11-14-2013
By the way, Ollie, Mr. Barnes provided a link to a specific ABX test of amps. Here it is again:

http://webpages.charter.net/fryguy/Amp_Sound.pdf

This is one of the specific reports that were summarized in the AES paper, so you can see how these tests are typically done. Not every test report is going to be found on the Web. But in my experience, this is a pretty good example of the whole process.
arnyk's Avatar arnyk 02:52 PM 11-14-2013
Quote:
Originally Posted by mcnarus View Post

By the way, Ollie, Mr. Barnes provided a link to a specific ABX test of amps. Here it is again:

http://webpages.charter.net/fryguy/Amp_Sound.pdf

This is one of the specific reports that were summarized in the AES paper, so you can see how these tests are typically done. Not every test report is going to be found on the Web. But in my experience, this is a pretty good example of the whole process.

Besides building some of the ABX equipment used, I was also a listener in that test, if memory serves. The article is a good reflection of what actually happened and also is a good practical example of ABX testing. There was a corresponding test involving the same people and CD players. CD players with live switching is very hard. Amps are easy.
amirm's Avatar amirm 03:15 PM 11-14-2013
Quote:
Originally Posted by 67jason View Post

What does it matter how many papers I got from aes? Is it an ego thing? The more I obtained the more credible I am? Is that it?
Please don't take this personally but yes, it absolutely means you have no credibility in this argument. You cannot ask the other to read AES reports which you yourself have not found worthy to read. There is incredible amount of knowledge and data in conference/journal papers that routinely disputes what the vocal majority thinks in this forum. Not having read it, you will equate what makes sense to your gut as the truth. And that gut feeling may very well be wrong.

I realize it is outside of the means of many to perform such research. Given that, perhaps it is better to not be so confrontational on the topic. Because the arrow can on a dime turn toward you as it did in this interchange smile.gif.
diomania's Avatar diomania 03:37 PM 11-14-2013
Quote:
Originally Posted by amirm View Post

Please don't take this personally but yes, it absolutely means you have no credibility in this argument. You cannot ask the other to read AES reports which you yourself have not found worthy to read. There is incredible amount of knowledge and data in conference/journal papers that routinely disputes what the vocal majority thinks in this forum. Not having read it, you will equate what makes sense to your gut as the truth. And that gut feeling may very well be wrong.

I realize it is outside of the means of many to perform such research. Given that, perhaps it is better to not be so confrontational on the topic. Because the arrow can on a dime turn toward you as it did in this interchange smile.gif.
Isn't it worse for someone who's read those AES papers to say, "As unfair as it might be, I am going to punt that question." to a question if jitter difference between S/PDIF and HDMI is audible?
beaveav's Avatar beaveav 03:58 PM 11-14-2013
Boy, that escalated quickly!

http://www.youtube.com/watch?v=Uh7tgX_Uaqs

I stabbed a man in the heart.

wink.gif
amirm's Avatar amirm 04:48 PM 11-14-2013
Quote:
Originally Posted by diomania View Post

Isn't it worse for someone who's read those AES papers to say, "As unfair as it might be, I am going to punt that question." to a question if jitter difference between S/PDIF and HDMI is audible?
I answered that question in a follow up article I wrote for Widescreen Review Magazine 6 or so months ago. Have not had time to put it in our online library so you have to buy the back issue to read it. Here is a picture of the measurement setup and equipment I tested for that article:

i-T8VfGXr-XL.jpg

It is the most extensive and up to date analysis of HDMI and S/PDIF anywhere.
beaveav's Avatar beaveav 04:57 PM 11-14-2013
^Somebody's ego isn't fitting on my screen. Looks like I need a bigger monitor. rolleyes.gif

"...the most extensive and up to date analysis of HDMI and S/PDIF anywhere?" Uhm, anywhere? So I guess large companies that produce consumer A/V products never do any such testing.

Your picture just looks like a couple of stacks of overpriced gear alongside an old analog oscilloscope and a lower-cost (relatively speaking) Audio Precision.
Shaun B's Avatar Shaun B 01:05 AM 11-15-2013
Quote: arnyk
And just for grins, compare these two pages:

I did. But you linked me to two AVR tests. I was hoping to see separate components compared against the receiver.


Shaun B's Avatar Shaun B 03:43 AM 11-15-2013
Quote:
Peak power numbers tend to be short bursts in the audio world. An amp with a very stiff supply has essentially no headroom, so a 50 W amp with say 60 Vpp power rails will deliver very little more than the rated 50 W before clipping.

Why would a stiff supply result in no headroom? Just asking, not trying to argue,.


arnyk's Avatar arnyk 05:24 AM 11-15-2013
Quote:
Originally Posted by Shaun B View Post

Quote:
Peak power numbers tend to be short bursts in the audio world. An amp with a very stiff supply has essentially no headroom, so a 50 W amp with say 60 Vpp power rails will deliver very little more than the rated 50 W before clipping.
Why would a stiff supply result in no headroom? Just asking, not trying to argue,.

Good question. I think that the answer lies in how you define headroom. There are several relevant definitions:

(1) Headroom - defined as the difference between the maximum power that is available from the amp, and the amount that you ever actually use. I would call this local headroom because it relates to the specific system and user.

(2) Headroom or "Dynamic headroom" defined as the difference between the amp's maximum power output with a long-term steady state sine wave output (probably best called static maximum output or steady-state maximum outputs), versus the power available in short bursts (best called dynamic maximum or peak output). This is a global number because it can be measured on a test bench and is the same as long as it is measured under the same standardized conditions.

Amps with stiff power supplies tend to have the same long-term steady state output and short-term dynamic or peak output. In that sense they have no headroom.
arnyk's Avatar arnyk 05:27 AM 11-15-2013
Quote:
Originally Posted by Shaun B View Post

Quote:
And just for grins, compare these two pages:
I did. But you linked me to two AVR tests. I was hoping to see separate components compared against the receiver.

I provided you with links to two AVRs - one mid-fi and one high end. BTW have you ever done your own research in areas like this? I'd rather teach you to fish than keep giving you dead fish. ;-)
Shaun B's Avatar Shaun B 05:37 AM 11-15-2013
Quote:
Originally Posted by arnyk View Post


I provided you with links to two AVRs - one mid-fi and one high end. BTW have you ever done your own research in areas like this? I'd rather teach you to fish than keep giving you dead fish. ;-)


Yeah I know, but I thought the idea was comparing AVR's to separates. I thought that is what you set out to prove, that AVR's measure the same or better than high priced separates.


arnyk's Avatar arnyk 05:42 AM 11-15-2013
Quote:
Originally Posted by beaveav View Post

^Somebody's ego isn't fitting on my screen. Looks like I need a bigger monitor. rolleyes.gif

"...the most extensive and up to date analysis of HDMI and S/PDIF anywhere?" Uhm, anywhere? So I guess large companies that produce consumer A/V products never do any such testing.

Your picture just looks like a couple of stacks of overpriced gear alongside an old analog oscilloscope and a lower-cost (relatively speaking) Audio Precision.

+1

Amir's incessant baiting with these hyperbolic descriptions of alleged secret tests could be irritating given all of the questionable claims he previously made for week after week about how everybody with an AVR needs to run right out and buy an asynch USB DAC because of the high audible jitter he alleged was hiding in their AVR's HDMI inputs. The advice was largely irrelevant because most audiophiles drive their AVRs with cable boxes, stand-alone digital music players and blu ray players, not PCs or other devices with USB outputs.

There seem to be precious few common audiopile sources that even have USB outputs.

Amir has sort of left us hanging twice, once after he failed to show that HDMI jtter was actually audible, and again after he failed to show us any relevant way to circumvent it, perchance the audible jitter existed in the first place. This is compounded by the fact that he staked his reputation on a few technical tests that are now relevant to just a few AVRs, many of which have been subsequently replaced in the marketplace, and whose publisher seems to have abandoned doing that kind of testing.
67jason's Avatar 67jason 05:51 AM 11-15-2013
Quote:
Originally Posted by amirm View Post

Quote:
Originally Posted by 67jason View Post

What does it matter how many papers I got from aes? Is it an ego thing? The more I obtained the more credible I am? Is that it?
Please don't take this personally but yes, it absolutely means you have no credibility in this argument. You cannot ask the other to read AES reports which you yourself have not found worthy to read. There is incredible amount of knowledge and data in conference/journal papers that routinely disputes what the vocal majority thinks in this forum. Not having read it, you will equate what makes sense to your gut as the truth. And that gut feeling may very well be wrong.

I realize it is outside of the means of many to perform such research. Given that, perhaps it is better to not be so confrontational on the topic. Because the arrow can on a dime turn toward you as it did in this interchange smile.gif.

yeah....


no worries, I aint the least bit concerned on your views of my credibility. wink.gif
arnyk's Avatar arnyk 05:56 AM 11-15-2013
Quote:
Originally Posted by Shaun B View Post

Quote:
Originally Posted by arnyk View Post

I provided you with links to two AVRs - one mid-fi and one high end. BTW have you ever done your own research in areas like this? I'd rather teach you to fish than keep giving you dead fish. ;-)


Yeah I know, but I thought the idea was comparing AVR's to separates. I thought that is what you set out to prove, that AVR's measure the same or better than high priced separates.

I did show that by showing high priced separates that were electronically the same as lower priced AVRs with features removed.

But, I'll go the extra mile:

http://www.soundandvision.com/content/linn-chakra-c2200-and-c3200-amplifiers-ht-labs-measures

Linn Chakra C3200 Amplifier, $5,400

"Both channels driven continuously into 8-ohm loads:
0.1% distortion at 105.8 watts
1% distortion at 125.6 watts"

http://www.soundandvision.com/content/pioneer-vsx-1123-av-receiver-ht-labs-measures

" Pioneer VSX 1123 Price $600"

"Two channels driven continuously into 8-ohm loads:
0.1% distortion at 127.7 watts
1% distortion at 146.2 watts"
kbarnes701's Avatar kbarnes701 06:19 AM 11-15-2013
Quote:
Originally Posted by OllieS View Post
 
Quote:
Originally Posted by kbarnes701 
I can understand that you only have a scant understanding of science, but surely you are able to use Google?

Could you be any more cryptic?

 

So what did you get from reading the articles?


DonH50's Avatar DonH50 07:43 AM 11-15-2013
Quote:
Originally Posted by Shaun B View Post

Quote:
Peak power numbers tend to be short bursts in the audio world. An amp with a very stiff supply has essentially no headroom, so a 50 W amp with say 60 Vpp power rails will deliver very little more than the rated 50 W before clipping.
Why would a stiff supply result in no headroom? Just asking, not trying to argue,.

See Arny's response in post 194. The second explanation is my rationale as it relates to amplifier specifications. The practical examples are an amp with very limited power supply that can only provide full voltage and current briefly before the rails sag and thus the steady-state (long-term, FTC) power rating is much lower than the "dynamic" power available for brief transients. At the other end is an amp with a regulated power supply that provides essentially the same voltage no matter the load; dynamic headroom relative to the steady-state spec is essentally zero.

There are been very good amplifiers designed with either philosophy. Krell and some other amps use(d) regulated supplies and have ~0 dB dynamic headroom over spec. Bryston and some others were (in the past, have not looked recently) actually rated with 6 dB dynamic power.

I do not like "dynamic power" as a spec because parameters such as how much power for how long are rarely specified.

What Arny calls "local headroom" is that provided in normal operation, the power available from the amp beyond what you are using on average at your listening levels. That is clearly related to the steady-state and dynamic power ratings of the amp, but I was referring to headroom relative to the amp's specifed output ratings.

HTH - Don
OllieS's Avatar OllieS 07:58 AM 11-15-2013
Quote:
Originally Posted by arnyk View Post

I did show that by showing high priced separates that were electronically the same as lower priced AVRs with features removed.

But, I'll go the extra mile:

http://www.soundandvision.com/content/linn-chakra-c2200-and-c3200-amplifiers-ht-labs-measures

Linn Chakra C3200 Amplifier, $5,400

"Both channels driven continuously into 8-ohm loads:
0.1% distortion at 105.8 watts
1% distortion at 125.6 watts"

http://www.soundandvision.com/content/pioneer-vsx-1123-av-receiver-ht-labs-measures

" Pioneer VSX 1123 Price $600"

"Two channels driven continuously into 8-ohm loads:
0.1% distortion at 127.7 watts
1% distortion at 146.2 watts"

Thank you for providing these links! Interesting results given the price differences.
OllieS's Avatar OllieS 08:02 AM 11-15-2013
So I see the Pioneer has a higher power output into 8 ohms but the Linn Chakra has almost double the power into 4 ohms! Also the Pioneer has a higher signal to noise ratio? The only thing the Pioneer test results do not indicate are the THD+N result. On the Linn it's 0.006%.
arnyk's Avatar arnyk 08:24 AM 11-15-2013
Quote:
Originally Posted by OllieS View Post

So I see the Pioneer has a higher power output into 8 ohms but the Linn Chakra has almost double the power into 4 ohms! Also the Pioneer has a higher signal to noise ratio? The only thing the Pioneer test results do not indicate are the THD+N result. On the Linn it's 0.006%.

You seem to be making facts up:

http://www.soundandvision.com/content/pioneer-vsx-1123-av-receiver-ht-labs-measures

Pioneer: "Into 4 ohms the amplifier reaches 0.1 percent distortion at 129.1 watts and 1 percent distortion at 165.7 watts."

Pioneer test result with THD+N specified, not absent as you seem to be claiming

http://www.soundandvision.com/content/linn-chakra-c2200-and-c3200-amplifiers-ht-labs-measures

Linn: " Into 4 ohms, the amplifier reaches 0.1 percent distortion at 197.3 watts and 1 percent distortion at 221.5 watts"

197 watts is only about 50% more than 129 watts, not twice as you are misleadingly claiming.

Note that 50% more power is less than a 2 dB difference. Run the volume on your AVR up or down by 4 clicks and tell me if you think that it is worth the difference in price. ;-)

Also note that the Pioneer is a true 7.1 multichannel AVR while the far more expensive Linns are only 2-3 channels.
FMW's Avatar FMW 10:02 AM 11-15-2013
Quote:
Originally Posted by Shaun B View Post


Yeah I know, but I thought the idea was comparing AVR's to separates. I thought that is what you set out to prove, that AVR's measure the same or better than high priced separates.

Just look at the specifications for any two amps and compare them. Audibility begins when distortion is at 1% or higher and when frequency response measures 3 db from flat. What you will find is that all of them have inaudible distortion and inaudible variance from a flat frequency response. If you want to do some blind testing yourself, knock your socks off. Most of us have already done it and have shared our experience.
Shaun B's Avatar Shaun B 10:25 AM 11-15-2013
Quote:
Originally Posted by FMW View Post


Just look at the specifications for any two amps and compare them. Audibility begins when distortion is at 1% or higher and when frequency response measures 3 db from flat. What you will find is that all of them have inaudible distortion and inaudible variance from a flat frequency response. If you want to do some blind testing yourself, knock your socks off. Most of us have already done it and have shared our experience.


How would I go about doing such a test? Can I do it at home?


Shaun B's Avatar Shaun B 10:29 AM 11-15-2013
Quote:
Originally Posted by arnyk View Post


You seem to be making facts up:

http://www.soundandvision.com/content/pioneer-vsx-1123-av-receiver-ht-labs-measures

Pioneer: "Into 4 ohms the amplifier reaches 0.1 percent distortion at 129.1 watts and 1 percent distortion at 165.7 watts."

Pioneer test result with THD+N specified, not absent as you seem to be claiming

http://www.soundandvision.com/content/linn-chakra-c2200-and-c3200-amplifiers-ht-labs-measures

Linn: " Into 4 ohms, the amplifier reaches 0.1 percent distortion at 197.3 watts and 1 percent distortion at 221.5 watts"

197 watts is only about 50% more than 129 watts, not twice as you are misleadingly claiming.

Note that 50% more power is less than a 2 dB difference. Run the volume on your AVR up or down by 4 clicks and tell me if you think that it is worth the difference in price. ;-)

Also note that the Pioneer is a true 7.1 multichannel AVR while the far more expensive Linns are only 2-3 channels.

What is the crosstalk figure? I see the more expensive processor has a much lower crosstalk compared to the Pioneer.


DonH50's Avatar DonH50 11:52 AM 11-15-2013
Crosstalk is how much signal from one channel appears in the other channel. In the real world the spec is essentially insignificant past maybe -60 dB; probably below -40 dB does not matter given typical mixes and systems. At -80 dB or so, the Pioneer spec, if you had one speaker sending out a signal of 100 W (very loud), the second speaker would be receiving 1 uW (10^-6 W) from crosstalk. Good luck hearing that, especially if anything is going on (i.e. any sort of signal) in the other speaker.
amirm's Avatar amirm 12:02 PM 11-15-2013
THD figure is an improper metric for audibility of distortion. It does not at all follow the rules of psychoacoustics. If I have a 5 Khz signal with a second harmonic at 10 Khz vs a 1 Khz signal with second harmonic at 2 Khz at the same level, the THD will be the same (with respect to the second harmonic). Audibility of these two situations however is very different due to frequency masking and resolution of auditory filters. One must know the spectrum of the harmonic distortions to determine the audibility which of course is never given (or often not measured individually).

We use THD because it used to be easy to measure and has become so ingrained in the industry that it continues to be used. But other than a gross measure, it has little value.
diomania's Avatar diomania 12:39 PM 11-15-2013
Quote:
Originally Posted by amirm View Post

I answered that question in a follow up article I wrote for Widescreen Review Magazine 6 or so months ago. Have not had time to put it in our online library so you have to buy the back issue to read it.
Or you could just answer that here now, no?
Online library, you mean your electronics dealer website?
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