Here horsey horsey
|
Platinum Member Username: Jan_b_vigneDallas, TX Post Number: 14047 Registered: May-04 | . http://www.soundstagenetwork.com/measurements/test_loudspeakers.htm |
|
Platinum Member Username: NuckPost Number: 13665 Registered: Dec-04 | Some reviews claim a Canadian tilt to a lot of the products that are built around, reviewed with and generally concerned with the NRC facility. I think that absolute neutrality and dead sound are a fair proving ground for measurement, and not emotion. Since the NRC has been a world standard for multiple uses over the years (including NASA, the URC(underwater research council) and many others, this facility, and it's attendant 'huge ear canal' is still among the worlds finest acoustic, resonance and frequency resonance facilities in the world. Maybe I am just puffing a bit, but hey, take what you get sometimes. |
|
Platinum Member Username: Jan_b_vigneDallas, TX Post Number: 14052 Registered: May-04 | . D@mn if socialism doesn't have it's virtues! Give me an "S" - give me an "O" ... The taxpayers fund the NRC and all Canadian companies get to use the resource instead of jacking up prices to pay for twenty individual labs of lesser quality. And twenty individual labs would be split between twenty individual speaker, aeronautics, washing machine, etc. companies who all wanted their own testing facilites. Very, very cagey idea those Cannucks had. It made a splash when the Canadian speakers hit the market, especially here in the US where the currency exchange favored the Canadians. They brought a bit of the British accuracy with a touch of US balls and spit and sold the he!! out of their stuff. You don't think there weren't a lot of US companies calling their Senators after that happened in several markets? "@##$%#@**&#@!!!! those #$#@@##@#*&&*^% guys, do something about this or don't expect to stay at the ^%&$^%%$%# guest house this month and forget the free *&(&^%$#^% h00kers!!!! Invade them, bomb their #@@##@%$%$ @sses all to He!!, I don't care, just %%$%#@*&**&^ing to something about this %^$@#@(&*^!!!!!!!" The link, however, is intended to be a touch of information for those who feel like reading. It's fairly short and to the point. Enjoy! . |
|
Gold Member Username: Mike3Wylie, Tx USA Post Number: 2157 Registered: May-06 | Good read, now if Nuck can get us the same info on the NRC facility more budget speakers from the Great White North may be snapped up. The information linked to above does help when one wants to understand if a speaker should even be a candidate for the system they are considering or upgrading. However, it does require one have sufficient knowledge of all associated gear in their kits in order to gain the most benefit from what the measurements provide. A long way of saying this should help someone eliminate what they may want to audition for whatever reason. |
|
Gold Member Username: DmitchellOttawa, Ontario Canada Post Number: 3123 Registered: Feb-07 | The NRC is a pretty amazing complex, takes of a pretty good chunk of the east end of Ottawa. I actually worked a contract there for awhile and it's quite the impressive place. I never got the see anechoic chamber unfortunately. The wind tunnel is cool too. |
|
Silver Member Username: HawkbillyNova Scotia Canada Post Number: 692 Registered: Jul-07 | I never really understood the THD+N measurement and how that equates to "accuracy". If I understand the purpose of a THD measurement, it's to determine what harmonics are added to the input signal that may cause apparent distortion to the original frequencies. What I'm not clear on is how that is likely to influence the ability of the speaker to make music. I know that back in the seventies there were a lot of amps that advertised incredibly low THD numbers like 0.0001 but they still didn't sound very good. How useful is this measurement in a speaker ? What should be implied from this measurement and what should not be implied ? |
|
Platinum Member Username: NuckPost Number: 13668 Registered: Dec-04 | CH, I never saw numbers on speakers like that |
|
Platinum Member Username: Jan_b_vigneDallas, TX Post Number: 14058 Registered: May-04 | . "I never really understood the THD+N measurement and how that equates to "accuracy". If I understand the purpose of a THD measurement, it's to determine what harmonics are added to the input signal that may cause apparent distortion to the original frequencies." In general "THD" means nothing. It is what it claims to be, "total" harmonic disortion. Nothing in that measurement alone that tells you about the breakdown of the harmonic content. J. Gordon Holt began Stereophile after a stint at High Fidelity seeing numbers that didn't match his perceived sound quality. One of his first assertions was it is not how much "total" HD existed but how it is broken down into its component parts. So an amplifier with 0.1% HD at the seventh, eighth and ninth order harmonics would tend to be more bothersome on certain program material than an amplfier with 1% HD at a lower second or even third order distortion. Additionally, most of the numbers you'll see are at the maximum useable power output of an amplifier and the wattage required for most program material normally falls well below full power where distotrion tends to be much, much lower. A broad observation which gained favor concerns the harmonic content of tubes and transistors and even and odd or low and high order distortions and how those measurements would relate to the "sound of tubes" or the "sound of transistors". IMO it was much easier to make those conclusions in the early days of solid state and somewhat less so today. To begin to make sense of any THD measurement you would want to see the spectral content of the output and how distortion overall rises with power and frequency and that would only be chapter one in the story of that amplifier. That measurement is reflected in part in Fig 7 of this Stereophile review; http://stereophile.com/solidpoweramps/pass_labs_xa305_power_amplifier/index4.htm l You can draw some broad inferences by looking at the spectral content though I've seen reviewers who say an amp sounds one way when the measurement would suggest something rather different. Among the many measurements "that matter" you should also pay attention to the IM measurement of any pre amp/power amp as this is often more irritating than harmonic distortion though no one truly agrees with just how much or how little distortion content is acceptable. Not many manufacturers quote IM specs. A few years back "TIM" (transient IM) was introduced as a way to measure a componet under more "music like" conditions. Still, your ears determine what quantity and spectral content you find more satisfying and to some extent whether you're likely to prefer tubes and FET's or bipolar transistors. Then the basic issue of static measurements against dynamic program material makes a convincing debate also. And so it goes. "What I'm not clear on is how that is likely to influence the ability of the speaker to make music." Broadly, it's not likely to influence the ability to make music at all in that "making music" involves lots of different attributes. ""One of the worst-kept secrets in audio engineering is that what we hear does not always correlate with what we measure." So wrote the late Richard Heyser 30 years ago ... ", http://www.stereophile.com/asweseeit/398awsi/index.html "I know that back in the seventies there were a lot of amps that advertised incredibly low THD numbers like 0.0001 but they still didn't sound very good." Measurements got pretty silly back in the late '70's but triple "0" THD numbers were generally confined to pre amps and tape decks. Receivers might boast double "0"'s but that was beneath the ability of any conventional measuring device of the day so it was kind of a moot point other than in the measurement, wattage wars that existed on paper. Sound was what you heard and lots of people loved their Pioneer SX1010. I never worked with anyone who didn't see that as a joke. "How useful is this measurement in a speaker ? What should be implied from this measurement and what should not be implied ?" Not much is said about speaker distortions because they can run in the 10-20% range at times. Again you want to consider what the content of the distortion amounts to and you'll find most drivers are producing low order and mostly even order distortion. Second and even third order harmonics are what we tend to hear as "musical" and are much more easily dismissed by our brains as equating to bad sound. High efficiency in a driver generally means lower distortion at normal listening levels though there may be other trade offs. Horn loading can lower distortion but might add colorations from the horn. Give one and take back two. Obviously the lower the distortion product the better but it comes down to how that distortion is reduced. In amplifiers it is common to run negative feedback in most designs, there is hardly a solid state amplifier that could survive if not for some amount of NFB. It's when the NFB becomes excessive that sound quality suffers while on paper numbers continue to look better and better. This led to a NFB war and many "zero feedback" designs that were unstable into most loudspeaker loads. In general a few dB of local NFB is far better than any amount of global NFB and a few designers advertised their products as "zero NFB" when what they had designed was a no global but some local feedback network. Triode vacuum tubes have an inherent NFB that helps the designer out and makes advertising copy much more dramatic. As was stated in the thread with Maris, there is quite a bit more correlation of measurements to sound quality available today but there's still a fair amount to be learned as the measurements still escape telling us about perception which mainly occurs in our brain and not in our ears. IMO reading the Stereophile reviews and measurements will give a better idea of how the two go together. . |
|
Silver Member Username: MagfanUSA Post Number: 542 Registered: Oct-07 | Is it not also true that your perception of distortion is frequency dependent? What will be OK at 100hz would drive you out of the room at 3k? Hey, I had a Pioneer SX-727! Man, was it ever cool looking. end. |
|
Silver Member Username: MagfanUSA Post Number: 543 Registered: Oct-07 | Just looked at NRC speaker test panel. Very good stuff, with 2 glitches. First, Measuring sensitivity on my panels in an anechoic chamber will result in a lower number than the speaker will produce in a real room. The backwave accounts for much output. Of course, room gain exists for all speakers, but in panels it is particularly important. Also, I am hung up on phase data. Sensitivity is nice, but only part of the amp compatibility story. And, being the tech nut I am, I also prefer my data presented in a Smith Chart. The NRC should be able to do a bang up job on this subject: |
|
Platinum Member Username: Jan_b_vigneDallas, TX Post Number: 14060 Registered: May-04 | . "Is it not also true that your perception of distortion is frequency dependent? What will be OK at 100hz would drive you out of the room at 3k?" In a speaker that would certainly be true but then again there's less energy at 3kHz. In amplifiers there is very likely more distortion at 100Hz than at 3kHz where HD drops with frequency until rising slightly at the upper end of the scale. So, yeah, if 3KHz were as "bad" as 100Hz, you'd very likely notice it but it still has that dependence on its spectral components. "The backwave accounts for much output." Plus 6dB if the speaker is a true dipole but most are not at all frequencies. The Smith Chart is difficult for most people to read but a better indicator of what is occurring no doubt. . |
|
Platinum Member Username: NuckPost Number: 13683 Registered: Dec-04 | JV, did you gain the 6db when building the dipole Ziggies? While 6 db might be a quadrupling of power in most conversations for us, was there that much? I do not recall the before/after, due to Scotch. |
|
Gold Member Username: DmitchellOttawa, Ontario Canada Post Number: 3129 Registered: Feb-07 | It must be Friday. |
|
Platinum Member Username: NuckPost Number: 13686 Registered: Dec-04 | Happy Thanksgiving weekend to our Canadian members! |
|
Gold Member Username: DmitchellOttawa, Ontario Canada Post Number: 3130 Registered: Feb-07 | Gobble gobble! |
|
Platinum Member Username: Jan_b_vigneDallas, TX Post Number: 14063 Registered: May-04 | . On paper the add is +6dB. For my speakers I would have guessed more like +4dB maybe a bit more real world. I don'got no stinkin'meter, man. . |
|
Gold Member Username: Mike3Wylie, Tx USA Post Number: 2159 Registered: May-06 | Hmmm, sounded more like 3.25 dB to me. But what do I know? |
|
Platinum Member Username: Jan_b_vigneDallas, TX Post Number: 14065 Registered: May-04 | . Don't know, you were drinking too, right?  There's a much larger difference if I connect them as bipoles (+ signal gives + movement of both drivers) both in SPL and bass extension. But the dipole connection sounds much better IMO and there's more allowable cancellation with the dipole set up where the front/rear drivers operate out of phase with each other. . |
|
Gold Member Username: Mike3Wylie, Tx USA Post Number: 2161 Registered: May-06 | Well, yeah... |
|
Gold Member Username: GavdawgAlbany, New York Post Number: 1308 Registered: Nov-06 | "Don't know, you were drinking too, right? " yup.., but who said it was a little? :-P |
Main Forums
Today's Posts- Home Audio Forum
- A/V Receivers Forum
- Amps Forum
- Cassette Forum
- CD Players Forum
- CD Recorders Forum
- DAC & Transports Forum
- DVD-Audio & SACD Forum
- Equalizers Forum
- Integrated Amps Forum
- iPod Docks Forum
- MiniDisc Forum
- Mini Systems Forum
- Digital Music Systems Forum
- Phono Forum
- Preamps Forum
- Speakers Forum
- Subwoofers Forum
- Tuners Forum
- Home Video Forum
- Home Theater Forum
- Car Audio Forum
- Accessories Forum
- All Forum Topics