The Audio Path In Consumer-Grade Products

[Pogre]

At least I'm part of the conversation. You come off a cheerleader for your team.

No one is asking you to read this thread. You have no positive contribution so please leave.

I have to cheerlead. I'm not educated enough on the subject to debate effectively. I chose the side that appeals to my sense of logic.

Honestly, I don't know enough to argue many of the points made, but I'm usually pretty good at sniffing out bs and this thread is cluttered with it. Plus I am actually learning things so I think I'll stick around.

 

[<eargiant]

I have to cheerlead. I'm not educated enough on the subject to debate effectively. I chose the side that appeals to my sense of logic.

Honestly, I don't know enough to argue many of the points made, but I'm usually pretty good at sniffing out bs and this thread is cluttered with it. Plus I am actually learning things so I think I'll stick around.

OK so you do like this thread that I started and have been patiently trying to continue with constructive discussion. Even though at times it feels like I'm getting hit from all sides. Debate requires prodding, provocation, challenging, disagreement. Who knows maybe at the end you'll realize that you already know everything and were right all along or maybe you won't. Maybe you'll learn something, maybe you won't.

If Dennis Murphy hadn't confirmed that what I heard in the Polk LSiM 703s was correct, most here would think I was full of $#*t because that's not what John Atkinson's measurements showed. Would your BS detector have been good enough to sniff out that I was right or would you have sided with John Atkinson's published measurements???

On your own admission you can't wait for me to get hammered. Honestly, I think that's why you're sticking around. Maybe a few others too but I suspect some do find this thread interesting to some extent. You've made your dislike of me well know in various scattered posts throughout. Look back and read the number of times you hit me with ad hominem comments. I have chosen not to address them and get sidetracked because that's how I roll but it's starting to get old. Silly jabs and one liners don't do anyone any good especially since we're all here to discuss, debate and learn.

You want to stay- fine, but take your pom-poms and sit quietly in the corner unless you have something constructive to add. I don't care what your viewpoint is, just quit with the jabs and keep it constructive.

 

[Pogre]

OK so you do like this thread that I started and have been patiently trying to continue with constructive discussion. Even though at times it feels like I'm getting hit from all sides.

On your own admission you can't wait for me to get hammered. Honestly, I think that's why you're sticking around. Maybe a few others too but I suspect some do find this thread interesting to some extent. You've made your dislike of me well know in various scattered post throughout. Look back a read the number of times you hit me with ad hominem comments. I have chosen not to address them and get sidetracked because that's how I roll but it's starting to get old. Silly jabs and one liners don't do anyone any good especially since we're all here to discuss, debate and learn.

You want to stay fine, but take your pom-poms and sit quietly in the corner unless you have something constructive to add. I don't care what your viewpoint is, just keep it constructive.

Ah, but you keep quoting me. You do know there's a block feature you can use and never see another one of my posts again? Nobody is forcing you to read my posts.

I don't dislike you, I disagree, strongly, with your opinions. I also find some of your replies condescending, belittling and insulting. There are no shortage of snotty replies from you in this thread, so you can climb off your high horse.

You feel like you're getting hit from all sides because virtually nobody on this forum is buying what you're trying to sell, yet here we are 17 pages later with you finding new ways to beat the same dead horse. You had to know when you so innocently started this thread a bunch of feathers were gonna get ruffled. I read most of your replies as disingenuous and full of bluster, but no substance. None.

So go ahead with your pointless thread and continue to be assailed from all sides. Maybe you'll go down as a martyr for all the audiophools.

 

[<eargiant]

Ah, but you keep quoting me. You do know there's a block feature you can use and never see another one of my posts again? Nobody is forcing you to read my posts.

I don't dislike you, I disagree, strongly, with your opinions. I also find some of your replies condescending, belittling and insulting. There are no shortage of snotty replies from you in this thread, so you can climb off your high horse.

You feel like you're getting hit from all sides because virtually nobody on this forum is buying what you're trying to sell, yet here we are 17 pages later with you finding new ways to beat the same dead horse. You had to know when you so innocently started this thread a bunch of feathers were gonna get ruffled. I read most of your replies as disingenuous and full of bluster, but no substance. None.

So go ahead with your pointless thread and continue to be assailed from all sides. Maybe you'll go down as a martyr for all the audiophools.

No, I've been ignoring your comments for a while. I only quoted you now when you jumped in again followed by the sidekick. It was against my better judgement but everyone have a breaking point.

Interesting how people feel that way and read that tone from people that they disagree with.

Anyway, you didn't answer my question. Would your BS detector have been good enough to sniff out that I was right about the LSiMs or would you have called me just another subjectivist "audiophool" and sided with JA's measurements?... I think we all know the answer to that, right.

 

[Pogre]

You didn't answer my question. Would your BS detector have been able to sniff out that I was right about the LSiMs or would you have called me just another subjectivist "audiophool" ?... I think we all know the answer to that, right.

Interesting how people feel that way and read that tone from people that they disagree with.

What does it matter? Your opinion on the LSiM's have nothing to do with this thread. For the record tho, my bs detector isn't infallible and I'll admit it, but sometimes it's pretty obvious...

You will never, ever convince me (or several others) that there are enough significant audible differences between amplifiers that justifies the thousands of dollars more in asking price. There are good reasons for buying that stuff, sure, but telling folks they can expect a "night and day" difference in sq is folly and misleading. Build quality, high quality parts, reliability, aesthetics and a crapload of cash burning a hole in your pocket are at least tangible reasons. 17 pages and you've yet to provide any evidence that the differences you're talking about are even audible.

Come back when you've participated in a dbt and have some evidence to support your claims. Otherwise you're just blowing hot air.

 

[<eargiant]

What does it matter? Your opinion on the LSiM's have nothing to do with this thread. For the record tho, my bs detector isn't infallible and I'll admit it, but sometimes it's pretty obvious...

Of course it matters. It wasn't an opinion, it was something I heard that did not jibe with published objective measurements from a respected 3rd party. I stuck to it even though the measurements indicated otherwise. Luckily I was proven right by a well respected speaker designer.

I'd also like to remind you that when your buddy started riding and mocking me early on about answering the "Jury" if SNR was the same as Dynamic Range most on this thread did not agree with me either. He thought I was in over my head. No one came to my defense and told him he was wrong. Did anyone even realize? Finally, hundreds of posts later I was proven right and he was proven wrong. How come no one picked up on that sooner and called out his ignorance? So, bottom line is - I don't care if the majority agrees with me or not.

You will never, ever convince me (or several others) that there are enough significant audible differences between amplifiers that justifies the thousands of dollars more in asking price. There are good reasons for buying that stuff, sure, but telling folks they can expect a "night and day" difference in sq is folly and misleading. Build quality, high quality parts, reliability, aesthetics and a crapload of cash burning a hole in your pocket are at least tangible reasons. 17 pages and you've yet to provide any evidence that the differences you're talking about are even audible.

Now I understand why you're so bitter, you are arguing with yourself. Based on your last paragraph it's clear you have no idea what we are even discussing here.

Do yourself a favor and please put me on ignore so you don't have to see my posts.

Peace

 

[Pogre]

Of course it matters. It wasn't an opinion, it was something I heard that did not jibe with published objective measurements from a respected 3rd party. I stuck to it even though the measurements indicated otherwise. Luckily I was proven right by a well respected speaker designer.

I'd also like to remind you that when your buddy started riding and mocking me early on about answering the "Jury" if SNR was the same as Dynamic Range most on this thread did not agree with me either. He thought I was in over my head. No one came to my defense and told him he was wrong. Did anyone even realize? Finally, hundreds of posts later I was proven right and he was proven wrong. How come no one picked up on that sooner and called out his ignorance? So, bottom line is - I don't care if the majority agrees with me or not.



Now I understand why you're so bitter, you are arguing with yourself. Based on the your last paragraph it's clear you have no idea what we are even discussing here.

I'm not bitter, and I'm right. You can't provide any evidence to support your claims. Also a recurring theme in this thread.

 

[PENG]

At least I'm part of the conversation. You come off a cheerleader for your team.

No one is asking you to read this thread. You have no positive contribution so please leave.

I trust you have the ability to stay nice and friendly, then you won't feel being attacked from all sides; and all may participate and focus on the technical and objective side. That's if you wish to keep your thread active..

 

[Pogre]

The objective or subjective one's?

More hot air.

 

[PENG]

Quick question- is there a large drop in volume when you switch the flat amp out on your Marantz combo? If so, how are you adjusting it to be equal?

I have to crank the volume right up past 12 noon position to make up for a >20dB loss of gain. If you don't volume match, you will think that without the flat amp you there is less punch.

I'd like to try it on my end also. Might be a good reason to get into REW. Would need guidance on mikes and set-up, etc.. Seems like so much can go wrong when making a comparison like this. Even John Atkinson blows it sometimes .

What JA does is obviously on a completely different level of accuracy and sophistication. My REW plots simply shows I can mix and match my different preamps, power amps, integrated amp and AVR that I own and the difference in frequency response, distortions measured by my $90 mic are so minute, compared with the difference measured by even if I move the mic a few inches. I posted once or twice before, would you like to see them again?

 

[ski2xblack]

So nobody took the bait I put forth on page two in the thread, way back when, that the Benchmark is a current dumper type thus devoid of crossover distortion, something which could very well result in audible differences, particularly within the all important first watt.

The Benchmark amp uses patented THX AAA (Achromatic Audio Amplifier) technology, which at least seems to share certain aspects of the old Quads (class A error correction amp/feed forward with class B dumpers). Here's Benchmark's John Siau explanations:

This is John Siau, VP and chief engineer at Benchmark

The THX patents are:

8,004,355
8,421,531

The patented topology uses feed-forward error correction to virtually eliminate crossover distortion. The technique is so effective that the output stage can be run in class-B operation while achieving very low distortion. This also allows class-H or class-G tracking rails without the usual distortion problems associated with these designs. THX has demonstrated a design that rivals the efficiency of class D amplifiers.

The THX topology was interesting to Benchmark for an entirely different reason:

The same feed forward error correction can be used to remove crossover distortion from a class-B amplifier can be used with class AB biasing to create an amplifier with extraordinarily low distortion.

Our goal was to achieve very low distortion, with a focus on low crossover distortion. We were willing to increase the power dissipation as much as necessary to optimize the distortion performance. The optimum solution uses some bias current, but much less than a traditional class AB. Distortion of the AHB2 is at the measurement limits of our AP 2722 and 2522 test stations.

The THX topology also allowed us to utilize two power supply rails in a class-H (or G) configuration without any measureable distortion penalty.

The AHB2 is significantly more efficient than a traditional class AB, and has much lower distortion. Power consumption is only 20W idle. A traditional class-AB of equivalent power would consume 100 to 120 W idle. For example, the similarly sized Bryston 3B consumes 120W idle.

Benchmark chose to build the amplifier with very low gain. Gain is only 9 dB instead of the more typical 20 to 30 dB gain found in most power amplifiers. This means that the AHB2 clips with a 22 dBu input instead of an 8.2 dBu (2 V RMS) input. The AHB2 is designed to accept studio-level input levels and this can significantly improve noise performance between connected devices. In my opinion, most power amplifiers have far too much gain.

Our design goals included a 130 dB SNR relative to maximum output. To achieve this performance we used very low impedances, and some very unique PCB layout techniques. We also chose to use a switching power supply so that we could eliminate 60 Hz magnetic components. The magnetic fields produced by a high frequency switching supply are much lower and are out-of-band.

We also chose a tightly regulated power supply. Most power amps use unregulated supplies because this is the most efficient use of resources if switching supplies are not used. Given switching supplies, tight regulation comes almost for free. Better yet, the power supply control loop can be made fast enough to react to all audio frequencies. The AHB2 does not rely on secondary capacitive storage.

 

[<eargiant]

I have to crank the volume right up past 12 noon position to make up for a >20dB loss of gain. If you don't volume match, you will think that without the flat amp you there is less punch.

Great, just wanted to confirm that there a big difference in yours also. What did you use to level match? I'd like to use the same if possible.

Also, how did you come up with the -20dB again? Does your tone board also have gain?

What JA does is obviously on a completely different level of accuracy and sophistication. My REW plots simply shows I can mix and match my different preamps, power amps, integrated amp and AVR that I own and the difference in frequency response, distortions measured by my $90 mic are so minute, compared with the difference measured by even if I move the mic a few inches. I posted once or twice before, would you like to see them again?

Sure, seems like a fun thing to mess with. What is mic brand/model and what else would I need.

What speakers do you use and have you ever used a parametric EQ to see if the REW and mic pick up minor differences?

 

[PENG]

Great, just wanted to confirm that there a big difference in yours also. What did you use to level match? I'd like to use the same if possible.

Also, how did you come up with the -20dB again? Does your tone board also have gain?



Sure, seems like a fun thing to mess with. What is mic brand/model and what else would I need.

What speakers do you use and have you ever used a parametric EQ to see if the REW and mic pick up minor differences?

I told you that in post# 302, The X10 amp has 20dB gain, my measurements show 23dB so I figure the tone amp must have a few dB gain.

Again, I just crank the volume up to level match. Also tried boosting the input, either way would work, there is no magic there but for better gain structure, boosting the input should be better. If I use my Oppo or Denon universal players then I won't need to boost the input at all, just cranking the volume up will provide the right amount of gain.

Speakers used are KEF LS50. No I have not use REW and minidsp to do anything yet.

If you want to have some fun and lean towards the objective side, get one of

THIS

That's how Pogre got started recently too.

 

[<eargiant]

So nobody took the bait I put forth on page two in the thread, way back when, that the Benchmark is a current dumper type thus devoid of crossover distortion, something which could very well result in audible differences, particularly within the all important first watt.

The Benchmark amp uses patented THX AAA (Achromatic Audio Amplifier) technology, which at least seems to share certain aspects of the old Quads (class A error correction amp/feed forward with class B dumpers). Here's Benchmark's John Siau explanations:

Wow, this thread is starting to tie together like a Seinfeld episode . I didn't miss your post but didn't comment because I didn't want to bring up Sansui at the time. It's the other manufacturer I know of that used Feed-Forward. The Super Feed-Forward amps came after my X1 and while I have never heard one they supposedly sound excellent. Again, another reason why I was so interested in the AHB2.

From Sansui:

"The history of Hi-Fi amps began in 1947 with the introduction of the Williamson amplifier, the first amp to reduce distortion effectively by using the NFB theory. The Williamson amp. in fact, became a reference amp by which later amps were judged.

There followed a series of new amp designs Tube amps gave way to transistor designs, output-transformer-less amps went output-capacitor-less. and finally, DC amps replaced AC models. Throughout this progression, new devices to reduce distortion still further proliferated. The NFB technique, however, remained indispensable It is no exaggeration to say that there would be no Hi-Fi amps today were it not for its application. It has been proven so effective that almost all amps on the market today make use of it.

Despite its ubiquity, however, NFB is limited in its effectiveness against distortion The NFB technique. as it has been used, cannot achieve 100% reduction of distortion no matter how refined or elaborate its application.

To accomplish this goal, Sansui had to find a breakthrough as startlingly new and different as the Williamson amp was in its time. We accomplished this with the Super Feedforward System. Feedforward theory actually dates back as far as 1928, when it was developed by H.S Black. Although it has long been applied in highly advanced communications systems, efforts to find Hi-Fi audio applications met with no success - until Sansui came up with a unique and untried solution to the problems the technique posed.

We did it by combining, for the first time in audio history, NFB and feedforward techniques. As excited members of the Audio Engineering Society (AES) were first told at a convention in London in February, 1980 (and again in Los Angeles in May of the same year). the Sansui Super Feedforward System has reduced all types of distortion - total harmonic intermodulation, switching, crossover and envelope to zero. Hi-Fi amplifiers will never be the same again."

 

[<eargiant]

I told you that in post# 302, The X10 amp has 20dB gain, my measurements show 23dB so I figure the tone amp must have a few dB gain.

Again, I just crank the volume up to level match. Also tried boosting the input, either way would work, there is no magic there but for better gain structure, boosting the input should be better. If I use my Oppo or Denon universal players then I won't need to boost the input at all, just cranking the volume up will provide the right amount of gain.

Speakers used are KEF LS50. No I have not use REW and minidsp to do anything yet.

If you want to have some fun and lean towards the objective side, get one of

THIS

That's how Pogre got started recently too.

Are you're level matching by ear or using an SPL meter?

BTW, the LS50s are very nice. I know many will disagree but I did a side by side (not in my home) with the CM5s and I found them to be of a similar vein. I'd still like to get a pair in here.

Ohh believe me, I'm more objective than you guys think but I trust my ears. Nobody's is going to convince me that a low cost "flat" measuring speaker is going to hold a candle to you LS-50s. I don't care how close the graph is.

Side note: When I went to the unveiling of the new Technics line and heard their SB-C700 bookshelf speakers I was very impressed. Give them a listen if you can.

 

[PENG]

Wow, this thread is starting to tie together like a Seinfeld episode . I didn't miss your post but didn't comment because I didn't want to bring up Sansui which is the other manufacturer I know of that used Feed-Forward. The Super Feed-Forward amps came after my X1 and while I have never heard one they supposedly sound excellent. Again, another reason why I was so interested in the AHB2.

From Sansui:

"The history of Hi-Fi amps began in 1947 with the introduction of the Williamson amplifier, the first amp to reduce distortion effectively by using the NFB theory. The Williamson amp. in fact, became a reference amp by which later amps were judged.

There followed a series of new amp designs Tube amps gave way to transistor designs, output-transformer-less amps went output-capacitor-less. and finally, DC amps replaced AC models. Throughout this progression, new devices to reduce distortion still further proliferated. The NFB technique, however, remained indispensable It is no exaggeration to say that there would be no Hi-Fi amps today were it not for its application. It has been proven so effective that almost all amps on the market today make use of it.

Despite its ubiquity, however, NFB is limited in its effectiveness against distortion The NFB technique. as it has been used, cannot achieve 100% reduction of distortion no matter how refined or elaborate its application.

To accomplish this goal, Sansui had to find a breakthrough as startlingly new and different as the Williamson amp was in its time. We accomplished this with the Super Feedforward System. Feedforward theory actually dates back as far as 1928, when it was developed by H.S Black. Although it has long been applied in highly advanced communications systems, efforts to find Hi-Fi audio applications met with no success - until Sansui came up with a unique and untried solution to the problems the technique posed.

We did it by combining, for the first time in audio history, NFB and feedforward techniques. As excited members of the Audio Engineering Society (AES) were first told at a convention in London in February, 1980 (and again in Los Angeles in May of the same year). the Sansui Super Feedforward System has reduced all types of distortion - total harmonic intermodulation, switching, crossover and envelope to zero. Hi-Fi amplifiers will never be the same again."

Anyone can adopt anything in their design whether it is feed forward, feedback, or both. It doesn't mean one is better than the other as it depends on some many other factors. if it was so simple that one is superior regardless, then we will only have one such single design. Btw, I took control systems in my final year option so I do have a good idea how each works, and done enough to pass exams but again, just because an amp employs feed forward, does not mean it will, though it may, produce better specs and measurements than one that doesn't. Regarding crossover distortions, even class AB amps can reduce if not eliminate crossover distortions well below level that humans can detect. So class A is not absolutely the best either. Some class AB amps also run in class A for the first several watts. I agree with ski2xblack's point about "something which could very well result in audible differences, particularly within the all important first watt." but the key word is "could.."

 

[<eargiant]

Anyone can adopt anything in their design whether it is feed forward, feedback, or both. It doesn't mean one is better than the other as it depends on some many other factors. if it was so simple that one is superior regardless, then we will only have one such single design. Btw, I took control systems in my final year option so I do have a good idea how each works, and done enough to pass exams but again, just because an amp employs feed forward, does not mean it will, though it may, produce better specs and measurements than one that doesn't. Regarding crossover distortions, even class AB amps can reduce if not eliminate crossover distortions well below level that humans can detect. So class A is not absolutely the best either. Some class AB amps also run in class A for the first several watts. I agree with ski2xblack's point about "something which could very well result in audible differences, particularly within the all important first watt." but the key word is "could.."

Don't disagree with anything there.

 

[PENG]

Are you're level matching by ear or using an SPL meter?

BTW, the LS50s are very nice. I know many will disagree but I did a side by side (not in my home) with the CM5s and I found them to be of a similar vein. I'd still like to get a pair in here.

Believe me, I'm more objective than you guys think but nobody's is going to convince me that a low cost "flat" measuring speaker is going to hold a candle to you LS-50s. I don't care how close the graph is.

I have taken enough measurements to know by the position of the master volume. For you, I will use the spl meter as well but not today. I have been working long hours taking measurements of volume setting vs preamp and power amp output level for Nordvest ( http://forums.audioholics.com/forums/threads/denon-avr-x3300w-7-2-atmos-dts-x-a-v-receiver-review.107572/page-4), so I need to take a good rest.

 

[PENG]

Don't disagree with anything there.

And feed forward or not, I have read enough to know now that integrated you have is a real keeper. It could well be among the best integrated ever made for under $5K (today's value). I probably won't trade it for my SC-7 and SM-7 simply because for 2 channel use, I generally prefer the flexibility offered by separate components. That's why I have only 1 integrated amp, so far.

 

[<eargiant]

I have taken enough measurements to know by the position of the master volume. For you, I will use the spl meter as well but not today. I have been working long hours taking measurements of volume setting vs preamp and power amp output level for Nordvest ( http://forums.audioholics.com/forums/threads/denon-avr-x3300w-7-2-atmos-dts-x-a-v-receiver-review.107572/page-4), so I need to take a good rest.

No need, I wasn't implying that you were off. Just wanted to confirm how you did it. I trust your ability to get it right by ear. Experience does that, I get where your coming from. I've done it both ways, using a cheap Radio Shack SPL meter or the Audio Technica "Installed Sound Support" iPhone app so I trust my ears too. As you know the range is small anyway, you're either way under or way over.

If you use a better quality SPL meter let me know, I'd like to buy it (unless it's crazy expensive).