ethanwiner
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What makes really good speakers sound really good?
Buddha
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"What makes really good speakers sound really good?"

Good measurements, of course!

Ethan, you should specify what kind of full range driver.

mrlowry
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You East Coast people have all of the fun.

ethanwiner
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Quote:
Good measurements, of course!


Well, I aim to find out.


Quote:
you should specify what kind of full range driver.


Uh, I mean a full range speaker system, not a single driver silly!

--Ethan

Buddha
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So, an eight foot tall Acoustat electrostatic full range driver would qualify?

Sound Lab A-1?

Or, are you thinking cones?

Grosse Fatigue
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Easy one: the drivers, cones, electrostatic, horn, whatever..

ethanwiner
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Quote:
Sound Lab A-1?
Or, are you thinking cones?


I'm looking for any truly excellent speakers people will lend me for my tests. Anyone near me is welcome to email me for a much more detailed explanation of what I have in mind.

--Ethan

JSBach
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How do YOU define a 'really good speaker'? Something that measures up to a set of objective standards, gives you goosebumps or maybe both?
I trust your measurements are to be conducted in a very large anechoic chamber.
And sorry, I'm not flying my Soundlabs back to the States for you to play with. I'd hate to learn they aren't 'really good speakers'.

ethanwiner
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Quote:
How do YOU define a 'really good speaker'? Something that measures up to a set of objective standards, gives you goosebumps or maybe both?


Something that sounds really good. Seriously. The conventional wisdom is that accurate speakers - flat response, low distortion and ringing - sound best. I'm not convinced this is always the case.


Quote:
I trust your measurements are to be conducted in a very large anechoic chamber.


Of course. At great personal expense since I'm funding this myself.

--Ethan

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Seriously. The conventional wisdom is that accurate speakers - flat response, low distortion and ringing - sound best. I'm not convinced this is always the case.

One thing I've learnt since installing sub-woofers that tailor their response to compensate for a particular room's 'response' is that a flat bottom end can be the last thing you want. Without that ability to compensate for peaks and dips in your environment flatness in that region can be a curse. (Granted, the speaker should be capable of a flat response in the bass region to start with) Another aspect that's often not spoken about is the axial response of tweeters. In some rooms flat treble power response over a wide angle can sandpaper your ears if the room isn't very carefully treated with absorption/ diffusion panels. And lets face it, what %, even in audiophile community, go to that kind of trouble, even if 'she who must be obeyed' permits it?
So, I think what I'm saying is that a speaker that measures 'perfectly' is only the starting point.

gkc
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What makes really good speakers sound really good? Aside from the bad and redundant adverbs, I suppose it is a fair question.

Whatever "what" is inside of the speaker box (or frame, in the case of electrostatics or other flat-panel designs) has to put music into your room that sounds like what you want your music to sound like. For me, the "sound like" is my memory of my most recent concert hall experience. That is not for everybody.

Flat. Perfectly neutral. Transparent. Forgiving. Mercilessly honest. Mercilessly sluttish. Kind to the sound-pressure meter, or (if blips are your favorite tunes) kind to the oscilloscope.

Winer, the moronic nature of this question betrays your obsession with setting up suckers to buy your worthless shit.

What makes "really" good speakers sound "really" good is their disappearance from your listening space, leaving only the music you love vibrant in the room. "Really" good speakers get out of the way and simply leave nothing but music in the wake of their leaving.

Of course, all of this vague bullshit depends on other factors. The software. The match of the amplification. The source components that pump the software.

Anybody who answers this ad deserves the hours of boredom and the useless information that will surely accompany an evening (or two, or three) with Winer.

You have been warned.

If you have to ask this question, I guess you don't have "really" good speakers, eh?

mrlowry
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While I don't agree with many of his stances on cables, amplifers etc. I would imagine that at the very least an evening with Ethan would allow someone the chance to learn a lot about two of the most important and universal topics in audio. Namely speaker placement and room acoustics. Two topics that most people know nearly nothing about and what they often think they know is either completely wrong or made up of half-truths. The fact that he gives away so much good information on the company website with only the chance that someone will buy their products says volumes about him. A company in his position could easily say, "buy the products from us THEN we'll give you the specifics on how to use them properly."

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Flat. Perfectly neutral. Transparent. Forgiving. Mercilessly honest. Mercilessly sluttish. Kind to the sound-pressure meter, or (if blips are your favorite tunes) kind to the oscilloscope.


Wrong, flat response below,say, 100hz can be a recipe for disaster or do you want to claim digital room analysis and correction, as installed on some sub-woofers, is useless snake oil?

Quote:
What makes "really" good speakers sound "really" good is their disappearance from your listening space, leaving only the music you love vibrant in the room. "Really" good speakers get out of the way and simply leave nothing but music in the wake of their leaving.

Yes, and many speakers that measure flat under anechoic conditions sure as hell don't disappear.

Quote:
Of course, all of this vague bullshit depends on other factors. The software. The match of the amplification. The source components that pump the software.

So, what happened to the listening room?

Quote:
Anybody who answers this ad deserves the hours of boredom and the useless information that will surely accompany an evening (or two, or three) with Winer.

I've told Mr W he wont be getting a loan of my speakers. Thanks for the warning but I can, and others too probably, handle Mr W's somewhat outragious claims with one hand tied behind my back.

]

bifcake
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I don't quite understand why you have an issue with Ethan's little project? He wants to find out what characteristics make people prefer certain speakers over others. If you don't feel this is relevant or pertinent to your musical enjoyment, you don't have to participate.

I have spent a few evenings with Ethan and I didn't mind his company in the least. He is a gracious host, knowledgeable and fun. You make him out to be some sort of a boorish monster and he's far from that.

I think this is an interesting idea and even if Ethan fails to find the characteristics of a good speaker, I admire him for trying.

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Quote:
What makes really good speakers sound really good? Aside from the bad and redundant adverbs, I suppose it is a fair question.

Whatever "what" is inside of the speaker box (or frame, in the case of electrostatics or other flat-panel designs) has to put music into your room that sounds like what you want your music to sound like. For me, the "sound like" is my memory of my most recent concert hall experience. That is not for everybody.

Flat. Perfectly neutral. Transparent. Forgiving. Mercilessly honest. Mercilessly sluttish. Kind to the sound-pressure meter, or (if blips are your favorite tunes) kind to the oscilloscope.

Winer, the moronic nature of this question betrays your obsession with setting up suckers to buy your worthless shit.

What makes "really" good speakers sound "really" good is their disappearance from your listening space, leaving only the music you love vibrant in the room. "Really" good speakers get out of the way and simply leave nothing but music in the wake of their leaving.

Of course, all of this vague bullshit depends on other factors. The software. The match of the amplification. The source components that pump the software.

Anybody who answers this ad deserves the hours of boredom and the useless information that will surely accompany an evening (or two, or three) with Winer.

You have been warned.

If you have to ask this question, I guess you don't have "really" good speakers, eh?

Clifton,

As a musician I am around live music constantly, in my practice studio, in my teaching studio and attending concerts 3-4 times a week.

I agree that this makes wonderful aural benchmark for a stereo system.

The Dallas Symphony is a top tier orchestra that used to play in a lousy hall (State Fair Music Hall).
The DSO appeared to have no dynamics, the life was sucked out, no definition of line, muddy as hell.
Then they moved to the Myerson, one of the finest concert halls in the country.

They sounded like a new orchestra, everything that was lacking was now there in abundance.

I equate this to the speaker/room interface in a home system.
You can have the finest speakers in the world but they won't sound that good in a lousy , untreated room.

You are attacking your own credibility here when you launch such an unfounded attack on Etan's products.

By extension you are attacking GIK, ASC and other manufacturers who use the same principles and materials that Ethan uses.

Your beef with him is both boring and unfounded.

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Clifton, if you are not convinced that room treatments do not have an effect, I would encourage you to collect strong scientific evidences for your belief and share it with us: Trust us, with good scientific evidence we will believe you. Unfortunately talking bad of Ethan, with absolutely no proper scientific basis to support your point only weakens your stance. We are all ears if you could provide us with an convincing argument. - Pradeep

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Quote:

By extension you are attacking GIK, ASC and other manufacturers who use the same principles and materials that Ethan uses.

Your beef with him is both boring and unfounded.

aint that the truth. only here would we see room treatments being branded as "worthless shit" , and magic pebbles lauded...

I guess he had to fill the space that he normally uses to talk about how much he makes or how much his gear costs or how he is an amazing megasupertrader, so he attacks Mr. W.

tom collins
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man cliff, you swallow a bad jalapino this morning? i usually find your commentary interesting and thought provoking if a little abrasive (fine with me). i think you are mistaken on this one and even if you are not, why the slam on ethan?

ethanwiner
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Quote:
only here would we see room treatments being branded as "worthless shit" , and magic pebbles lauded...


LOL, indeed.

BTW, my project has nothing to do with room acoustics or bass traps etc. It's pure consumerist research, and is a personal project unrelated to my company.

--Ethan

andy_c
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Hi Ethan,

Are you aware of Floyd Toole and Shaun Olive's work in this area? Floyd has a couple of papers on this, in which they actually did speaker blind tests by mounting them on a big lazy susan that was hidden behind acoustically transparent screens. They also did some interesting things with characterizing the reliability of listeners by how consistently they graded and described the same speaker blind. There are two PDFs on this subject: this one and this one. Their work was related to correlation of loudspeaker measurements to listener preferences. The newer speaker models from Revel, JBL, and Infinity incorporate this research.

Also, Sean Olive has a really good blog that deals with these issues. It is here. Here's an amusing quote from the listener reliability studies that Sean and Floyd did.

"Most surprising was the relatively poor performance of the audio reviewers, who despite their credentials and years of professional experience, performed 1/5 as well as the trained listeners, and 15 full percentage points lower than the audio retailers."

LOL!

gkc
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Pradeep, ncdrawl, tomjtx, and Tom Collins, you missed my point. A "really good speaker" has to sound good in your room. Not Ethan's, or anybody else's. Yours. How you get "there" is up to you, your tastes, and, yes, your room. Nothing I wrote excludes adjusting the speaker you are considering to your room, via positioning experiments or acoustic room treatments (or, usually, a combination of both). You like 'em in the demo room, at the dealer's or at the show, and now you have to get 'em to perform in your room, by hook or by crook (usually, a lot of both).

Tom, there is no such thing as a "bad" jalapeno.

Winer is doing marketing research. If that doesn't bother you (even though he denies it), then participate.

You can't polish a turd. A bad speaker put into an environment uniquely perfect to its bad performance is still a bad speaker. A good speaker (however you personally define "good") will sound superb in an optimum acoustic setting and okay in an average-to-bad one. A bad speaker (however you personally define "bad") will sound bad in any room. Winer's post begs that question. Winer's post topic overtly mentioned nothing about room acoustics. Look at the title. "What makes really good speakers sound really good?" Yet, he wants you to participate in a (ahem) marketing experiment. I understand. We are in a recession/depression (do your own hair-splitting), and not only Winer, but EVERYBODY, needs your discretionary $$$.

If you all had bought gold when I told you to, then it wouldn't matter, would it? Sorry. I had to get that in. No, I am NOT an investment advisor. I was just trying to do you all a favor. Sigh.

Did the above piss you off? If so, good. Ncdrawl. Of course, you probably weren't around, when I wrote my screed a couple-three years ago, when gold was at about $400. If you had bought then, you would have watched in dismay as the Great Yellow Turd sank another 30 bucks. But, if you had kept your cool and held, you would be looking at a double+ on tomorrow's opening.

Oops. We're off topic. Give Winer a chance, by all means. He needs your cash. Go ahead. Get your money's worth. Post for us all how his magical room treatments turn your air-pushin' turds into disappearin' paragons. I can't wait for the results of THIS experiment.

Even though there is no such thing as a bad jalapeno, there are, most certainly, bad speakers. No matter how good the room is. It is up to you to listen at the dealer's (or your friend's house, or the show), mentally "place" said speakers in your own home, then take them home, then listen, then try to optimize them to your own environment.

Winer is merely another salesman. Alex, if you like what he is selling, then for cryin' out loud buy it and post a rave review. He wants fodder for his marketing scheme. This is obvious, from his prior posts.

Hey! If you are a Winer-lover, then by all means go for it! He needs the business. Shell out those Shekels.

But don't get on MY ass for not believin' the bullshit...

Cheers, and happy tunes, no matter HOW you get 'em.

bifcake
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In all the time I spent socializing with Ethan, not once did he ever mention his products (unless I asked), much less try to sell me anything. I invited him to my friend Roger's house to hear different equipment and I suggested that he bring his room treatments. He refused, saying that he didn't want to make a social call into a sales call. I have nothing but respect for Ethan. I don't know where you come off making your claims, but as far as I'm concerned, you're talking out of the depths of your ass.

commsysman
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On the other hand, anyone who wants to "bring back DUP" is without question a certifiable masochist...can we trust this man?...lol....

ncdrawl
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"wont turn bad speakers into good ones"
nope, wont do that!. No one has said as much...

but.. the fact of the matter:
if you are hearing your speakers in a room that is not optimized, you are not hearing what the speakers are capable of. You are not really even hearing the speakers at all! If you want to get the best possible sound, the room HAS to be treated. .. The ROOM is the most important aspect...it matters not if you have dropped 5 million or 500 on the gear. If the room isnt dealt with, youve thrown your damn money away.

but..
Why the personal attack, Clifton?

ncdrawl
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DUP was cool man, he just didnt know when to shut up.


Quote:
On the other hand, anyone who wants to "bring back DUP" is without question a certifiable masochist...can we trust this man?...lol....

ncdrawl
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I love Harman's Automated Speaker Shuffler

Loudspeaker positional effects are controlled by an automated speaker mover that shuffles each loudspeaker into the same exact position within 3 seconds. During the test, an acoustically transparent but visually opaque curtain (shown in the up position here) is dropped in front of the loudspeakers so that the listener is not biased by visual factors such as loudspeaker size, brand, price,etc

SAS Audio
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Quote:
DUP was cool man, he just didnt know when to shut up.

As a couple of quick examples, among many, Dup thought the frequency response specification of a preamplifier, 20-25k -0.1db, meant the high frequency response literally dropped over a cliff at 25khz. (Actually it was -1.0db well over 100khz.) He also did not understand that the slew rate figure is worthless because it can be manipulated by simply changing the amplitude of the signal. So an inferior device can be manipulated to look superior by simply using a higher B+ voltage, allowing for a higher signal level to calculate the slew rate. That and all of his attacks on seemingly every string.

He may be a fine friendly individual in person, but do we want him back to propogated more pseudo-scientific mis-information and attacks?

ncdrawl
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SAS, if we are talking about pseudoscience and misinformation,

hell, I can think of a couple dealers here that stand out..

at least DUP wasnt a dealer, and had nothing to gain by stating what he believed... not the case with the folks I am thinking of..

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Quote:
SAS, if we are talking about pseudoscience and misinformation,

hell, I can think of a couple dealers here that stand out..

at least DUP wasnt a dealer, and had nothing to gain by stating what he believed... not the case with the folks I am thinking of..

So do we need another?

ncdrawl
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Quote:
So do we need another?

DUP did not bother me. He was a nice foil for those that swung the opposite way. Balance is always good, you see. Passionate folks have my respect.

ethanwiner
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Quote:
Are you aware of Floyd Toole and Shaun Olive's work in this area?


A little, but I'll check out all the links you posted. I may already have those PDFs, not sure.


Quote:
"Most surprising was the relatively poor performance of the audio reviewers, who despite their credentials and years of professional experience, performed 1/5 as well as the trained listeners, and 15 full percentage points lower than the audio retailers."


Not surprising to me at all. Next time you read a review in a magazine, whether a recording type or hi-fi type, look for a list of associates gear. If the reviewer talks about a loudspeaker's imaging but has no acoustic treatment, you know immediately they're full of crap and have no idea what good imaging is all about.

--Ethan

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Passionate folks have my respect.

ROTFLMAO!

andy_c
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Quote:
He also did not understand that the slew rate figure is worthless because it can be manipulated by simply changing the amplitude of the signal.

If that is the case, then what's being measured isn't the slew rate at all - the device is still in a quasi-linear region. The slew rate is the absolute maximum time rate of change of voltage that can be achieved at the output of the device. Sometimes this is difficult to measure because of input low-pass filters that can cause the amp or preamp to clip before it slews with a square wave input. With some devices, you can measure a large-signal, high-frequency sine wave to get around this. In such a case, the "sine wave" output looks like a triangle wave when slew-rate limiting. But with some power amps having very high slew rate, the high-frequency sine wave technique can cause common-mode conduction in the output stage that either triggers the protection circuitry or destroys the amp. In such a case, it may be necessary to remove the shunt capacitor in the input LPF and use a square wave to measure slew rate.

Also, some devices (such as non-feedback amps and preamps) effectively won't slew-rate limit at all if the load is not capacitive, so a slew rate spec makes no sense for such devices.

bifcake
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On the other hand, anyone who wants to "bring back DUP" is without question a certifiable masochist...can we trust this man?...lol....

HA!!! Actually, I met DUP a few times and I've never found him disagreeable. He's a genuinely nice guy. He has his opinions and he's entitled to them. I thought that many of his opinions had merit. I think that DUP, not unlike the Kaiser is greatly misunderstood.

BTW, DUP opened my eyes to pro gear and that pro gear can sound really great at a fraction of the price of audiophile gear. This is true especially when it comes to electronics. His AVA rebuilt Hafler amps smoked my friend's McIntosh MC501 at 1/8 the price. His $1k Tascam CD player/recorder gives a run for the money to $5-$6k CD players out there.

I still correspond with him via e-mail. He says hi and he asked me to reiterate the following:

1. You need BIG drivers and many of them to reproduce live sound.

2. You need a great amount of WATTS to drive the speakers at realistic levels without compression and breakup.

3. Audio equipment has to be priced for mortals. $100k speakers and $50k amps are a ripoff

4. If it can be heard, it can be measured. There are no secrets when it comes to acoustic design and there is no magic. If a manufacturer refuses to say what's inside a component, chances are, he's pulling wool over your eyes.

5. Cables should be picked based on application and the application dictates the type of specs of the cable. Once cables meet specs, it is irrelevant which brand or model you choose. Cables shouldn't cost in the hundreds of dollars. If cables are expensive or incorporate some sort of unorthodox, secret or magic technology, chances are that you're being ripped off.

DUP thanks you for your indulgence and wishes you well.

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Well, you just destroyed your argument to bring DUP back...you covered his entire output in one post.

Now, if people want to get a feel for the good ol' days with DUP here, copy and paste that with intentional misspellings so as to make the entire first page of the forum the same post. Viola! DUP redux!

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Quote:
you covered his entire output in one post.


That could be said for everyone posting here, even including me.

Yet we persist and state the same tired crap over and over again anyway.

--Ethan

PS: Bring back DUP!

SAS Audio
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Quote:

Quote:
So do we need another?

DUP did not bother me. He was a nice foil for those that swung the opposite way. Balance is always good, you see. Passionate folks have my respect.

However, Dup provided misinformation constantly. And I believe Stephen stated in DUP is banned because he was causing problems with others posting. Those should be enough reason. So should he be allowed to post misinformation and make matters worse?

SAS Audio
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Quote:

Quote:
He also did not understand that the slew rate figure is worthless because it can be manipulated by simply changing the amplitude of the signal.

If that is the case, then what's being measured isn't the slew rate at all - the device is still in a quasi-linear region. The slew rate is the absolute maximum time rate of change of voltage that can be achieved at the output of the device. Sometimes this is difficult to measure because of input low-pass filters that can cause the amp or preamp to clip before it slews with a square wave input. With some devices, you can measure a large-signal, high-frequency sine wave to get around this. In such a case, the "sine wave" output looks like a triangle wave when slew-rate limiting. But with some power amps having very high slew rate, the high-frequency sine wave technique can cause common-mode conduction in the output stage that either triggers the protection circuitry or destroys the amp. In such a case, it may be necessary to remove the shunt capacitor in the input LPF and use a square wave to measure slew rate.

Also, some devices (such as non-feedback amps and preamps) effectively won't slew-rate limit at all if the load is not capacitive, so a slew rate spec makes no sense for such devices.

And if one component has 100 volts on the plate and another has 200 volts on the plate, the slew rate can still be misleading as both could be measured in the linear region even though the max output voltage needed is only 2 volts. Thus with 200 plate volts, it will have a higher slew rate even though the lower voltage component has greater bandwidth. See my point?

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Quote:
And if one component has 100 volts on the plate and another has 200 volts on the plate, the slew rate can still be misleading as both could be measured in the linear region even though the max output voltage needed is only 2 volts. Thus with 200 plate volts, it will have a higher slew rate even though the lower voltage component has greater bandwidth. See my point?

Dunno about tube amps, but slew rate has little to do with bandwidth in general. If you're measuring the device in the linear region, then you're not measuring slew rate. Slewing only happens when a stage reaches its maximum current driving a capacitive load, so you hit the maximum time rate of change of I/C volts/sec. If the maximum time rate of change varies with signal level, it's not slewing and what you're measuring isn't the slew rate.

gkc
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andy, I love ya, buddy, but who GIVES a shit about slew rate if the sound is good (by, of course, your own personal definitions of "good sound)."

If the sound puts you into the G-zone, why bother with how it measures? If you aren't sure, then, by all means measure. But don't stop listening. And never, NEVER abandon good sound because of conflicting measurements.

Your ears and your heart, after all, know better. Why argue with your brain? Listen, listen, and listen. Then buy (only if you are dissatisfied with what you currently own...) what sounds better.

Happy tunes.

gkc
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Ethan, why should Floyd and Shaun matter (whoever THEY are...)??? Are their ears attached to your head?

Hell, pay your grand and check into some academic mind-fuck session, and put all the numbers (volts, ohms, slew-rates, and damping factors) into a 200-page curriculum syllabus. Then, take the multiple-choice final.

Will it help you validate and enjoy (if they come in that order, be careful how you spend your dough...) the tunes?? Do you need validation???

The further away from music this thread gets, the more useless it becomes to anyone who loves music.

ncdrawl
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a lot of people do. if it can be heard it can be measured. your "listen only" philosophy is fine for you, but everyone aint you, fella. so how about chilling out with the chest thumping and trumpeting of your anti-science philosophy, eh?
to paraphrase you..
who gives a shit about your opinion but you?

if you know the science, your ears will follow.


Quote:
\ who GIVES a shit about slew rate if the sound is

gkc
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If you know your ears, the science will follow.

ncdrawl
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The further away from music this thread gets, the more useless it becomes to anyone who loves music.

bullshit. knowing the science behind sound reproduction and the reasons why speakers sound a certain way can only heighten the listening experience..

"one cannot suffer from knowing too much"

or maybe in your case a more apt quote would be
"ignorance is bliss"

ncdrawl
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If you know your ears, the science will follow.

that was a joke, right?
the rules of science bending to accomodate frailty of human hearing?
maybe in audiophilebizarroworld..

jesus.... only on audiophile forums!

andy_c
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a lot of people do. if it can be heard it can be measured. your "listen only" philosophy is fine for you, but everyone aint you, fella.

In particular, such technical matters are of interest to people designing amplifiers for instance (sas for business and myself in the DIY realm). Not everyone will be interested in such things of course.

bifcake
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If the sound puts you into the G-zone, why bother with how it measures? If you aren't sure, then, by all means measure. But don't stop listening. And never, NEVER abandon good sound because of conflicting measurements.

Your ears and your heart, after all, know better. Why argue with your brain? Listen, listen, and listen. Then buy (only if you are dissatisfied with what you currently own...) what sounds better.

Happy tunes.

There are a few problems with that notion. For one thing, if all equipment is subjective, then there is no such thing as bad piece of gear because no matter how subjectively bad something may be, there will always be someone who likes it.

Secondly, if measurements are irrelevant and it's all subjective anyway, then, there is no reason to strive to make objectively better equipment. All that one has to do is provide different syrup flavors.

Finally, if there is no objective definition of "good" or "reference", then there is no such thing as snake oil. Anyone can sell you anything, no matter how ludicrous and there will always be someone who claims that a particular piece of poop placed in a particular bowl at a particular time of day made their music sound (place your favorite adjective here).

By getting down to the factors that matter most, we can place an objective definition of "good" and we can place a value, whether monetary or enjoyment value on a particular component. This allows us to develop an objective reference and to strive to improve components to equal or surpass the reference.

ethanwiner
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no matter how subjectively bad something may be, there will always be someone who likes it ... there is no reason to strive to make objectively better equipment. All that one has to do is provide different syrup flavors ... no matter how ludicrous and there will always be someone who claims that a particular piece of poop placed in a particular bowl at a particular time of day made their music sound (place your favorite adjective here).


Indeed, hence the popularity of vinyl and toob gear.

Sadly, you have now opened the door to a new realm I'm sure I don't want to be exposed to. Next we'll see May and Geoff and their followers claim that Poodle poop in a bowl "sounds better" than Yorkie poop.

--Ethan

SAS Audio
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And if one component has 100 volts on the plate and another has 200 volts on the plate, the slew rate can still be misleading as both could be measured in the linear region even though the max output voltage needed is only 2 volts. Thus with 200 plate volts, it will have a higher slew rate even though the lower voltage component has greater bandwidth. See my point?

Dunno about tube amps, but slew rate has little to do with bandwidth in general. If you're measuring the device in the linear region, then you're not measuring slew rate. Slewing only happens when a stage reaches its maximum current driving a capacitive load, so you hit the maximum time rate of change of I/C volts/sec. If the maximum time rate of change varies with signal level, it's not slewing and what you're measuring isn't the slew rate.

Check out this as one easy source: http://en.wikipedia.org/wiki/Slew_rate

SR = 2pi X F X Vpk

SR = slew rate
pi = 3.1416
F = frequency
Vpk = peak amplitude of waveform
X = times, multiplication

I see frequency and peak voltage in the equation. As one can see, the slew rate can be manipulated by changing both the frequency and B+ voltage. And for a given frequency, adjusting the B+ voltage and thus signal voltage will affect the slew rate.

Hope this helps.

SAS Audio
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a lot of people do. if it can be heard it can be measured. your "listen only" philosophy is fine for you, but everyone aint you, fella. so how about chilling out with the chest thumping and trumpeting of your anti-science philosophy, eh?
to paraphrase you..
who gives a shit about your opinion but you?

if you know the science, your ears will follow.


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\ who GIVES a shit about slew rate if the sound is

Seeing your previous three posts.

NC, why do you dismiss PHDs in both physics, chemistry, as well as dozens of engineers from major corporations, all the while having no expertise in the fields whatsoever. Claiming to know more than them is simply self promotion and arrogance.

Preaching anti-science is unethical, deceptive, and misleading to the consumer. Capacitors are a prime example of how sofisticated test instruments miss DA and ESR in capacitors, yet a simple voltmeter can measure DA. This has been posted several times before.

It would also be nice if you would finally give your name and where you work, since you claim to be a recording engineer.

andy_c
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Check out this as one easy source: http://en.wikipedia.org/wiki/Slew_rate

Yes, I know how to take the derivative of a sine wave. That's freshman calculus. What I said was that slew rate and bandwidth are not in general related. I'm referring to the bandwidth of the amplifier here, not the frequency of the signal.

Let's take the example of an op-amp or op-amp-like circuit with Miller frequency compensation, whose output stage has a gain of 1.

The gain-bandwidth product of such an op-amp in rad/sec is gm/C where gm is the input stage transconductance and C is the Miller compensation capacitor value. Also, the slew rate in Volts/sec is Imax/C, where Imax is the maximum output current of the input stage. You can easily see from the above that one can keep the gain-bandwidth product (and thus the bandwidth of the amplifier at a fixed gain) constant by scaling gm and C by the same factor, call it K. Let's say K=0.5. If the input stage bias current is not changed, then the maximum output current of the input stage does not change either. However, because K=0.5, the compensation capacitor has been cut in half, along with the input stage transconductance.

So what we've done in this case is keep the bandwidth of the amplifier constant, yet doubled the slew rate (because we've cut the compensation capacitor in half). That's what I meant by the amplifier bandwidth and slew rate being unrelated in general.

There are examples such as the AD797 in which the gain-bandwidth product is very large (100 MHz), yet the slew rate is quite modest (20 V/uS). You'll also find other op-amps whose GBW is not nearly as large, yet their slew rate is much larger. FET input op-amps have this property exactly because of the reduced input stage transconductance as mentioned in the example above.

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