View Full Version : SE Measurements
davef
10-11-2006, 05:57 PM
Ok, so after a few months of work -- I am pleased to say that I have developed a complete computer automated setup for an entire suite of loudspeaker measurements....
What normally took me perhaps 8 hours of engineering work -- can now be completed in under 30 minutes -- and I don't even have to be in the lab :)
Measurements included in the suite:
*Quasi-Anechoic on-axis full range frequency response
* Horizontal dispersion (15, 30,45 degs off-axis - to right and left)
Vertical dispersion and symmetry (5, 10,15 degs off-axis - above and below)
*Listening window (an averaged response that best represent what the listener hears -- averages both on-axis and off-axis measurements)
* Impedance + Electrical Phase (also called a Bode plot)
* Waterfall CSD plot (Cumulative Spectral Decay)
I think this covers it all -- is there anything else you guys would like to see?
Also, would you prefer I post the graphs unsmoothed or 1/3 octave? Using a 5dB scale or 10dB scale? Understand that if I post measurements of our products using 1/3 octave smoothing and a 10dB scale (like many other manufacturers) -- the response plots will look *almost* like perfectly straight lines...
Personally, I like the completely unsmoothed graphs on a 5dB scale as they are extremely revealing --- however --- much of the general public might not understand this difference in scaling and smoothing and they might wrongfully assume one loudspeaker is more linear than another based on these scaling differences...
Curious as to your thoughts...
Thanks!!!
Jonnyozero3
10-11-2006, 07:04 PM
Damn Dave. I need another beer to cogitate on this :p
Edit - Okay, my Becks Dark thinks that showing both is best. Have a smoothed graph in an obvious place for comparison to other products, but then also have the unsmoothed ones a click or two away so us nit-pickers can check them out :)
P Seastrand
10-11-2006, 07:42 PM
Also, would you prefer I post the graphs unsmoothed or 1/3 octave? Using a 5dB scale or 10dB scale? Understand that if I post measurements of our products using 1/3 octave smoothing and a 10dB scale (like many other manufacturers) -- the response plots will look *almost* like perfectly straight lines...
Personally, I like the completely unsmoothed graphs on a 5dB scale as they are extremely revealing --- however --- much of the general public might not understand this difference in scaling and smoothing and they might wrongfully assume one loudspeaker is more linear than another based on these scaling differences...I suggest you post both with the "industry standard" as the default for comparision purposes, with a link, or page down option to see the unsmoothed graphs for the details.
BradJudy
10-11-2006, 08:07 PM
I don't care much for 1/3 octave smoothing, but I don't know that unsmoothed is right either (too much misinterpretation). Perhaps you can split the difference with 1/6 or 1/12 octave smoothing? I do like the idea of showing a graph "using competitor's standards" and another using "Ascend's high standards" or something like that. Of course, that's most effective if you can demonstrate what an unnamed competitor's speaker looks like in the two scales/resolutions.
Automating that many angles of off-axis down to 30 minutes is great!
I'm curious about the QA full range measurements (feel free to skip this question if you feel an answer would give too much away) - how low are you able to measure accurately? Full range QA would require a lot of free space in my understanding.
davef
10-11-2006, 08:40 PM
I'm curious about the QA full range measurements (feel free to skip this question if you feel an answer would give too much away) - how low are you able to measure accurately? Full range QA would require a lot of free space in my understanding.
Depends on how you take the full range measurement... close mic or ground plane...
I prefer ground plane for the low end and "splicing" this into the anechoic measurement. Yes -- ground plane requires a lot of open space --- (the only advantage of running out of inventory :o ) but even the ground plane measurements I take are only accurate down to about 50Hz (good enough for most loudspeakers). I also use close mic techniques to verify the accuracy and to determine response below the limits of ground plane.
These measurements are definitely NOT automated -- and quite time consuming.. However, once these are taken -- everything else is a breeze and all the splicing calculations are done through macros I developed.
Of course, website upload and image tweaking in photoshop is a tedious process --- but the difficult tasks of generating the graphs and off-axis measurements (I take a total of 144 off-axis measurements) are now completely automated.
One important factor in all of this is that I still have the CBM-170 which was measured by the NRC. This allows me to closely calibrate based on these measurements. If I remember correctly, the NRC chamber is precisely accurate down to 60Hz or so.
Quinn
10-11-2006, 09:24 PM
I second giving both and explaining the differences in graph resolution and how to read other companies graphs to determine what resolution they are using.
curtis
10-11-2006, 09:26 PM
Mmmmm....Becks Dark...one of my favorites!
Oh....I think posting both would be a good thing as well, but like Brad posted may misinterpret the unsmoothed graph. "Other" companies sometimes don't even tell you what resolution they are using and leave a lot up to interpretation.
davef
10-11-2006, 09:51 PM
I like the idea of posting both versions of the graphs -- unsmoothed and using a 5dB scale -and- 1/3 octave on a 10 dB scale. With the macros I developed, this is easy to do -- it is a bit more work with image processing and website uploads but I enjoy doing things differently -- and this is definitely a bit different :)
I will start with 170 SE measurements and go from there.
Great stuff!!
Dave are you going to include the 200's in this as well?
When buying any product I like as much information as possible. However presentation is everything, taking it one step further with both graphs seems like a great idea. Maybe with a statement like "What others won't show you".
curtis
10-12-2006, 07:28 AM
Dave are you going to include the 200's in this as well?
I believe the 200's already have most of the measurements Dave listed.
JackT
10-12-2006, 07:34 AM
I believe the 200's already have most of the measurements Dave listed.
I like how the FR is displayed in the ever-popular 6dB/division scale!
I have been bothered by that FR measurement, BTW. It does not seem to match up at all to the stated range of the loudspeaker. The graph looks like the HTM-200 does ~ 110Hz-20 KHz +- 3 dB. (Also there's that wierd flat portion at the upper frequencies that looks like something was saturated or something...)
MikeAndAnnie
10-12-2006, 08:33 AM
Depends on how you take the full range measurement... close mic or ground plane...
I prefer ground plane for the low end and "splicing" this into the anechoic measurement. ...
Dave - I would suggest not doing any splicing. I think many folks become suspicious of the accuracy of a curve when it is pieced together, as who is going to piece together any 'bad' parts? However, if I could see a close mic curve AND a spliced anechoic, together with an explanation of each, that would work.
Just my 2 cents....
Jonnyozero3
10-12-2006, 03:08 PM
Dave - I would suggest not doing any splicing. I think many folks become suspicious of the accuracy of a curve when it is pieced together, as who is going to piece together any 'bad' parts? However, if I could see a close mic curve AND a spliced anechoic, together with an explanation of each, that would work.
Just my 2 cents....
FWIW, I think that's more in depth than 98% of consumers know or care about. I think it's great to have as much information available as possible (and I'd love to see it all broken down and explained, of course), but you can make it overly complicated to the point where the consumer either feels dumb, or feels that it's complicated in order to actually hide something or mislead. I would be careful of that.
Also - until this thread I wasn't even aware that splicing happened on some FR response plots. And, frankly, I have no idea what other companies may have done so. That's my own ignorance though :p
Asliang
10-12-2006, 04:04 PM
This sounds great! I can't wait to see the graphs!
Awesome work Dave!
bikeman
10-12-2006, 04:40 PM
FWIW, I think that's more in depth than 98% of consumers know or care about.
Also - until this thread I wasn't even aware that splicing happened on some FR response plots. And, frankly, I have no idea what other companies may have done so. That's my own ignorance though :p
If you're not aware, I think 98% is WAY too low an estimate. ;)
David
Jonnyozero3
10-12-2006, 05:08 PM
If you're not aware, I think 98% is WAY too low an estimate. ;)
David
Well, I'm aware that those such as us (who desire such information) account for approximately 0.14 percent of the cosumer population...but I'm also aware that we are much more important (of course we are!), so I calculated a fudge factor of 14.285714285714285714285714285714 to get to a weighted result which amplified our importance in the estimate. So, instead of 0.14%, I bumped us up to 2%, leaving the rest of the "normies" at a compressed 98%. Selfish thing for me to do...I know. But I was hoping my skewed numbers would, in a backhanded way, convince Dave to not only provide all the above information, but photos of the warehouse, testing chamber(s), diagrams, schematics, personal notes (handwritten included, legible or not), in order to better inform us about his product. :D
davef
10-12-2006, 06:24 PM
Jon ---
Your post is cracking me up! My baby has been driving us nuts -- this is the first good laugh I have had in a few days.. Thank You!!! Very Much Needed!!! :D
Jonnyozero3
10-13-2006, 01:01 PM
Anytime Dave ;) Glad to hear the baby has healthy lungs :D
curtis
10-20-2006, 10:28 AM
Ummm....I just noticed, because someone posted a graph in the AVS forum, the new measurements are up:
http://www.ascendacoustics.com/pages/products/speakers/cmt340m/cmt340mmeas.html
http://www.ascendacoustics.com/pages/products/speakers/cbm170/cbm170meas.html
curtis
10-20-2006, 10:32 AM
Ummm....I just noticed, because someone posted a graph in the AVS forum, the new measurements are up:
http://www.ascendacoustics.com/pages/products/speakers/cmt340m/cmt340mmeas.html
http://www.ascendacoustics.com/pages/products/speakers/cbm170/cbm170meas.html
Check out the "smoothed" versions!! :)
Mike^S
10-20-2006, 12:01 PM
lol, it's a straight line. :D
Mag_Neato
10-20-2006, 12:06 PM
A couple of flatliners, eh! :eek:
Jonnyozero3
10-20-2006, 12:19 PM
Holy wow.
I'd greatly appreciate an explanation of how to read the CSD graph. Many thanks!
Dan
Quinn
10-23-2006, 07:17 AM
"We actually post a very revealing graph on our website called the cumulative spectral decay. This is seldom understood, but still a highly important measurement. This is a measurement of a fast impulse consisting of thousands of frequencies ranging from 400Hz to 20Khz. What the graph reveals is what “noise” is left over once the initial impulse stops (in milliseconds). " http://forum.ascendacoustics.com/showpost.php?p=7712&postcount=17
Use the search function with the term, cumulative spectral decay. You will find more explanations but most of it is in regard to the differences between the old 170 and 340 classsics. I didn't turn up anything regarding the new SE versions and CSD.
This is a little off topic but in the specifications section there are no crossover points or type given. Are they listed somewhere else? If not does anyone know what they are.
Mag_Neato
10-24-2006, 08:27 AM
The crossover is the heart-n-soul of a speaker, so it is proprietary information that Ascend probably wants to keep out of the hands of it's competitors. Sure, someone can disect a crossover and reverse-engineer it, but they are not going to give it away for free. ;)
Dave put in a ton of R&D for the SE's with the related time/financial investment. I assume he has been awarded, or applied for, patents. I know the SEAS tweeter is exclusively his, with a variation available from SEAS. I ASSume the same goes for the new woofers.
The crossover is the heart-n-soul of a speaker, so it is proprietary information that Ascend probably wants to keep out of the hands of it's competitors. Sure, someone can disect a crossover and reverse-engineer it, but they are not going to give it away for free. ;)
Dave put in a ton of R&D for the SE's with the related time/financial investment. I assume he has been awarded, or applied for, patents. I know the SEAS tweeter is exclusively his, with a variation available from SEAS. I ASSume the same goes for the new woofers.
Right now I'm looking for speakers and the Ascends are some I'm considering. I've been to many web sites and I don't remember too many of them not listing what order the crossover is and what the crossover points are.
BradJudy
10-24-2006, 09:39 AM
This is really a vendor preference item. Let's do a quick survey of ID brands:
Axiom: x-over point, but not slope/order
AV123: varies by speaker, most have x-over point but not slope (some have slope, some have neither)
Aperion: no x-over info
SVS: no x-over info
Hsu Research: no x-over info
ACI: no x-over info
Home Theater direct: both x-over point and order
VMPS: x-over point, but not slope/order
Odyssey: no x-over info
I didn't go around and survey all of the big store brands since I didn't want to take that much time, but from the online brands it's clear there isn't a standard for what, if any, crossover info is given.
Quinn
10-24-2006, 10:05 AM
Ascend uses a 4th order Linkowitz-Riley crossover. About the only place it is mentioned is in The $ensible Sound (http://www.ascendacoustics.com/pages/reviews/TSSascendreprint.pdf) review in the paragraph at the top of page two. The crossover point in that article is for the Classic version. The SE's tweeter allows for a lower crossover. I don't know where the present crossover is and don't see an obvious artifacts on the CSD that would tell it's location.
curtis
10-24-2006, 11:21 AM
Right now I'm looking for speakers and the Ascends are some I'm considering. I've been to many web sites and I don't remember too many of them not listing what order the crossover is and what the crossover points are.
Out of curiosity, how will this information affect your decision?
Out of curiosity, how will this information affect your decision?
First off I'm not really a technical person as I can hardly even solder. :) But as an example a first order crossover that I've used in the past didn't have good power handling although it was very well integrated. It's just something along with measurements that I like to look at.
Ascend uses a 4th order Linkowitz-Riley crossover. About the only place it is mentioned is in The $ensible Sound (http://www.ascendacoustics.com/pages/reviews/TSSascendreprint.pdf) review in the paragraph at the top of page two. The crossover point in that article is for the Classic version. The SE's tweeter allows for a lower crossover. I don't know where the present crossover is and don't see an obvious artifacts on the CSD that would tell it's location.
Thanks for the info Quinn.
GaryB
10-24-2006, 12:16 PM
Out of curiosity, how will this information affect your decision?I know where he's coming from, Curtis. Part of Ascend's appeal for me, and, I suspect, many others, is that the success of the designs seems to result from a rigorous application of tried-and-true concepts, and not from some secret magic recipe. The speakers sound terrific, and also measure very well (in all respects). This combination of virtues, for some of us, has a very high "warm and fuzzy" quotient, which is partially derived from knowing something about the various design decisions.
Since Ascend's published specs and measurements are unusually comprehensive in other respects, the absence of crossover information does seem to be a bit of an anomaly. To jad5, I suggest you e-mail Dave F. directly and ask him your questions. He has, in the past, been very forthcoming when I have asked him similar technical questions myself.
curtis
10-24-2006, 03:13 PM
Understood.
I just think that giving the crossover point or type isn't as informative....it really doesn't tell you much.
GirgleMirt
10-24-2006, 03:57 PM
I hope I'm not opening a can of worms, what about "Total Harmonic Distortion + Noise"?
cumulative spectral decay, I was about to ask, but found this explanation by Dave midpage here :) thx! http://forum.ascendacoustics.com/showthread.php?t=856&page=2&pp=10&highlight=cumulative+spectral+decay
Other info: http://forum.ascendacoustics.com/showthread.php?t=978&highlight=cumulative+spectral+decay
davef
10-25-2006, 02:37 PM
Hi Guys,
I hope I'm not opening a can of worms, what about "Total Harmonic Distortion + Noise"?
THD is certainly possible but there are no standards for this type of test (besides possibly taking hours to perform depending on how many frequencies I test)
THD at what frequency? At what SPL level? To properly measure THD, I must feed a very low distortion sine wave to the speaker and take measurements from there. It is time consuming but I suppose we could pick a few specific frequencies to measure.
Right now I'm looking for speakers and the Ascends are some I'm considering. I've been to many web sites and I don't remember too many of them not listing what order the crossover is and what the crossover points are.
Crossover point (between woofer and tweeter) is not indicative of performance. Slope and Q, if understood, can indicate some level of performance (mostly driver integration and off-axis performance). A higher order crossover will generally provide better off-axis performance and higher power handling. The SE's use high order crossovers -- 4th order acoustic, variable slope filters.
I prefer not to publicly discuss info about our crossover networks. While there is no "magic formula" as GaryB stated, there are some "magic" techniques that I use and have refined over the past 20 years. Ever try asking Famous Amos for the recipe for his cookies :p
Hope this helps!
Lou-the-dog
10-25-2006, 09:05 PM
I prefer not to publicly discuss info about our crossover networks. While there is no "magic formula" as GaryB stated, there are some "magic" techniques that I use and have refined over the past 20 years. Ever try asking Famous Amos for the recipe for his cookies :p
Hope this helps!
I think what Davef is trying to say is that he would be more than happy to share all the details of his crossovers with you. But then he'd have to kill you. :eek: :D
Randy
Jonnyozero3
10-26-2006, 07:56 AM
Death by Best Buy Speaker Demo Room.....ouch......
This is really a vendor preference item. Let's do a quick survey of ID brands:
Axiom: x-over point, but not slope/order
AV123: varies by speaker, most have x-over point but not slope (some have slope, some have neither)
Aperion: no x-over info
SVS: no x-over info
Hsu Research: no x-over info
ACI: no x-over info
Home Theater direct: both x-over point and order
VMPS: x-over point, but not slope/order
Odyssey: no x-over info
I didn't go around and survey all of the big store brands since I didn't want to take that much time, but from the online brands it's clear there isn't a standard for what, if any, crossover info is given.
Yep HTD will give you that INFO, but they won't put up a simple FR graph.......
JackT
12-29-2006, 03:36 PM
Yep HTD will give you that INFO, but they won't put up a simple FR graph.......
Am I correct that Hsu does not provide FR graphs for anything? Do they provide that if you ask?
curtis
12-29-2006, 03:44 PM
Am I correct that Hsu does not provide FR graphs for anything? Do they provide that if you ask?
I don't think I have ever seen Hsu post a graph, but there are at least a few third party graphs and professional reviews with graphs.
Am I correct that Hsu does not provide FR graphs for anything? Do they provide that if you ask?
They have been asked about measurements more then once about their hb-1 speakers that they just ignore. They don't seem to have a lack of time with marketing. I just stopped visiting their web site. If you need to by two different types of subs for a bookshelf speaker there's a problem somewhere.
I'm not sure if they will or not,All I ever hear is the SVS punches ya harder, but that the HSU is more musical than the SVC subs(which BTW have a HUGE following as well), and I equate that to speed, maybe wrongly, but the ability to play successive notes quickly is important in the bass region as far as I am concerned, I played drums for 13 years, so I have listened up close to tight changes in Speed and Dynamics... a big WHOOOMPH isn't gonna get it done for me. I'd gladly trade in a bit of subsonic bass for music.
I like speed AND depth, and thats the reason I am probably going to build a Rythmic Direct Servo Sealed sub.
Some folks love SVC, some HSU
I am also not sure if HTD will or not, but I DO know that they don't have it visible on the website, cuz I looked.
They have been asked about measurements more then once about their hb-1 speakers that they just ignore. They don't seem to have a lack of time with marketing. I just stopped visiting their web site. If you need to by two different types of subs for a bookshelf speaker there's a problem somewhere.
You are referring to that new HighFreq. sub I take it?
curtis
12-29-2006, 03:55 PM
They have been asked about measurements more then once about their hb-1 speakers that they just ignore. They don't seem to have a lack of time with marketing. I just stopped visiting their web site. If you need to by two different types of subs for a bookshelf speaker there's a problem somewhere.
Why do you need to buy two different types of subs?
As much use FR graphs are for some, unless you can verify a manufacturer's graph or two with that of a third party, I don't think means much.
There is one graph of another manufacturer that does not come close to that if the measurement at Soundstage.
The MBM-12 is not required for anything. It is an enhancement that is said to benefit the listener due to more upperbass headroom and nearfield placement. If it is actually beneficial is another question.
The HB-1 does not require it. It is no different than any other bookshelf in that regard.
I think what Hsu has failed to do is convey the proper message/purpose of the MBM-12.
They have been asked about measurements more then once about their hb-1 speakers that they just ignore. They don't seem to have a lack of time with marketing. I just stopped visiting their web site. If you need to by two different types of subs for a bookshelf speaker there's a problem somewhere.
BTW who ever said they HAD to have both subs?
My GUESS?
ALOT more folks are buying smaller and smaller speakers, making the higher bass harder to acheive smoothly with any ONE sub, dividing the subs into 2 regions actually allows each sub to do it's dedicated duty, and do what it's BEST at.
Trying to play hard low notes, and then trying to play quick higher notes in succession is tough on ANY DRIVER, split the responsibility, and I would think there would be a cleaner note for note reproduction.
BTW, I kind of think it's a fad personally, but if folks like the split responsibility, and they HEAR a better overall sound, they will succeed there.
We'll see, but the reason I THINK it won't work out that well, isn't because it's flawed, it's because most people hardly even realize they need ONE sub..........
Thats my take, I could be WAY wrong.
The MBM-12 is not required for anything. It is an enhancement that is said to benefit the listener due to more upperbass headroom and nearfield placement. If it is actually beneficial is another question.
The HB-1 does not require it. It is no different than any other bookshelf in that regard.
I think what Hsu has failed to do is convey the proper message/purpose of the MBM-12.
I never said it was, I was asking him.
curtis
12-29-2006, 04:10 PM
I never said it was, I was asking him.
ooops....sorry, I new it was jad5, but I quoted you. I will fix it.
NP at all curtis, I kinda figured that.
m
I would like to see measurements on the hb-1 because I have doubts about the midbass energy it might have without the mbm. Wasn't it originally shown at the Cedia 2006 with the mbm? Curtis I agree with you about 3rd party measurements being more reliable than others but I try to have faith that manufacturers would be truthful until otherwise proven wrong. For instance I have never once doubted any measurement Ascend has put out. I guess I just expect that out of everyone.
curtis
12-29-2006, 04:40 PM
jad, I heard the HB-1 with an MBM-12 and VTF-3HO/turbo at the HES show in Los Angeles back in June....sounded very good. If I remember correctly, the higher crossover was at 80hz, with the MBM crossed to the HO at 50hz.
Also heard the HB-1 with no sub, the bass extension is no different than any other bookshelf with a +-3db of 60hz.
One thing about Ascend's graphs is at least the one of the classic 170 matched up well with the one done by Soundstage. The only other speaker company that I have seen with graphs that match with third party is Axiom.
I also agree on 3rd party measurements, 2 would be better even(with the SAME gear/conditions).
That would show folks whats really going on there.
Some of the claims I am seeing are a bit curious IMO.
Physics, while NOT the end all, do mean something IMO...........
As far as the faith is concerned.... I forget that at the door to my bank ATM.
curtis
12-29-2006, 04:50 PM
I also agree on 3rd party measurements, 2 would be better even(with the SAME gear/conditions).
That would show folks whats really going on there.
Some of the claims I am seeing are a bit curious IMO.
Agreed. I have no doubt that when Ascend speakers get measured again, they will measure very well.
Also heard the HB-1 with no sub, the bass extension is no different than any other bookshelf with a +-3db of 60hz.
If 60hz is an accurate +-3db and they don't have any other serious variations higher up then they shouldn't have a problem posting a FR graph.
curtis
12-29-2006, 05:05 PM
If 60hz is an accurate +-3db and they don't have any other serious variations higher up then they shouldn't have a problem posting a FR graph.
Agreed, but there are other speakers that measure well and the manufacturer doesn't advertise a graph.
Neither should HTD(as far as posting their own measurements), but they don't either, and some folks think they are the cats meow.
Maybe they are....
I dunno why, but I like to see it by the Manufacturer, then a second measurement by a 3rd party if possible.
curtis
12-29-2006, 05:14 PM
I'd tend to give a company extra credit for posting a verifiable measurement, rather knocking one if they didn't.
muzz, I am going to order some HTDs....you want to come out and listen to them? :)
I'd love to curtis.
I'd get to meet you and listen to some great tunage on some great speakers.
I'd guess the HTDs sound great from all the talk, I KNOW the Ascends do from personal listening.
I'd love to just take the 1/2hr drive over...... OOOOOO wait........ :(
curtis
12-29-2006, 06:08 PM
I'd love to curtis.
I'd get to meet you and listen to some great tunage on some great speakers.
I'd guess the HTDs sound great from all the talk, I KNOW the Ascends do from personal listening.
I'd love to just take the 1/2hr drive over...... OOOOOO wait........ :(
I don't give much credit to what someone says about a speaker on the forums much any more unless I know the person and his/her tastes. I have heard some speakers that others love, but only make me shrug my shoulders.
One of the greatest things I enjoy when people come over to listen to the speakers, or when I go somewhere to listen to speakers, is being exposed to great music that I hadn't heard before.
I'm hearing ya curtis, but physics have a tendency to make me think twice.
I guess as long as folks like their speakers, then thats all that really matters.....
Quinn
12-29-2006, 07:42 PM
The whole HTD thing on AVS from one person is a strange to me. HTD been around for about 5 years and has never gotten the posts like it is suddenly.
I thought about getting a pair of HTDs and doing my listening. I feel that I couldn't write anything up without it being a group listening session. I'd be written off as an Ascend homer if I didn't care for the HTDs.
I've heard the previous generation HTD 3s at a get together. That version didn't have a ribbon tweeter.
curtis
12-29-2006, 07:47 PM
I've heard the previous generation HTD 3s at a get together. That version didn't have a ribbon tweeter.
It was the old Level 4's that we heard. Not a bad speaker.
davef
12-30-2006, 12:20 AM
HTD is probably the only major ID loudspeaker I haven't heard or measured so I am curious about them too.
I do have some issues with the design of the Level 3 bookshelf. That style of ribbon tweeter is generally only usable from 4kHz on up -- and even that is pushing it for a small kapton ribbon. Ribbons like these usually get crossover over at around 6kHz.
According to the level 3 specs, the crossover point is 2700Hz. That is both, a very low crossover point for this style tweeter and a very high crossover point for a 6.5", stiff, high mass woofer (I must assume it is quite stiff due to the ceramic cone and it must be a heavy cone based on the impressive bass performance). These are all features not condusive to clean and accurate midrange performance. However, I could definitely be wrong and I do look forward for a chance to evaluate them in the future.
BradJudy
12-30-2006, 09:42 AM
Sounds like you need to place an order Dave. :)
I wonder if they are going to come out with a new level 4.
Jay_WJ
12-31-2006, 08:11 PM
As I described in my review, there's somthing wrong around the Level 3's crossover frequency. Most ribbon tweeters, including even highly regarded ones like Aurum Cantus, LCY, and Fountek, according to what I read in some DIYer's extensive test report, have significantly high 3rd- and higher-order harmonic distortions at frequency region below 4khz.
What I found is that the response of the Level Three around its CO frequency is weak and makes instruments sound unnaturally thin.
Anyway, I ordered Level Two to complete my speaker search for this season. :) I'll update my review when I audition them.
Speaking of measurements, I have been studying alot of graphs lately, and one of the things I've noticed is the SPL level used for +/-3db.
Why does it seems that some use 80db, and some use 85db?
I am especially paying attention to bass rolloff.
I have also noticed a sharp difference in impedance curves, cheaper speakers tend to have high spikes(40ohms :eek: ), I think I have tracked that down to crossover type, 2nd order/4th order etc...
I could be wrong on that, but there seems to be a correlation.
Now if there is a sharp spike in the audible range, wouldn't this frequency have a tendency to be lower in amplitude?
I noticed that 4th order helps keep the spikes in the lower frequencies, EDIT:Some below the speakers rated FR, and that more expensive speakers use these.
Any assistance on this would be great.
Thx
I know the answer to question 1, so disregard that 1 please.......
davef
01-03-2007, 12:00 AM
I have also noticed a sharp difference in impedance curves, cheaper speakers tend to have high spikes(40ohms :eek: ), I think I have tracked that down to crossover type, 2nd order/4th order etc...
I could be wrong on that, but there seems to be a correlation.
Now if there is a sharp spike in the audible range, wouldn't this frequency have a tendency to be lower in amplitude?
I noticed that 4th order helps keep the spikes in the lower frequencies, EDIT:Some below the speakers rated FR, and that more expensive speakers use these.
The impedance peaks you see represent an increase in reactance of the driver at that particular frequency. The summit of the peak is the point in which the driver has the most reactance to the frequency and is usually the resonance frequency of the driver.
The crossover network used will have varying affects on the overall impedance curves, but not significant unless impedance compensation circuits (Zobel networks) are used. The reason you might see smaller peaks with higher order crossovers is simple. Those resonant peaks are audible sources of distortion and should be damped. For a mid or high frequency driver, the crossover point for those drivers should be well above the frequency of the resonant peak. One damping method is by reducing the amplitude of that particular frequency (another damping method for lower frequencies is by port / cabinet tuning) and a higher order crossover will provide greater amplitude reduction below the -3dB point of the filter when compared to a lower order crossover given the same crossover point.
Impedance curves can be used to determine the port tune or cabinet tune (for a sealed enclosure) and overall load placed on the amplifier, but they should not be used to determine loudspeaker performance.
Thanks for the info dave.
m
curtis
04-18-2007, 11:54 PM
Maybe this is old news, but I just noticed for the SE models, more measurements/graphs have been added for:
Horizontal & Vertical Off-Axis + Listening Window @ 1 meter
Impedance + Electrical Phase
Cumulative Spectral Decay
Sam1000
04-19-2007, 10:37 AM
On avs, I saw one of the thread where the old 170 was measured and the graph had distortion details on it. Don't see that with new measurements. I'm not unhappy about it, but was little curious about it. Dave has already posted more than just a frequency response for the speakers. Many manufactures don't even post the FR graphs for their reference line.
curtis
04-19-2007, 10:42 AM
On avs, I saw one of the thread where the old 170 was measured and the graph had distortion details on it. Don't see that with new measurements. I'm not unhappy about it, but was little curious about it. Dave has already posted more than just a frequency response for the speakers. Many manufactures don't even post the FR graphs for their reference line.
Those distortion measurements for the classic 170 were from Soundstage's measurement set, not Ascend's.
Asliang
04-19-2007, 11:35 PM
I think its old news, I think it's been there for months...
davef
04-20-2007, 12:31 AM
Hi Sam,
On avs, I saw one of the thread where the old 170 was measured and the graph had distortion details on it. Don't see that with new measurements. I'm not unhappy about it, but was little curious about it. Dave has already posted more than just a frequency response for the speakers. Many manufactures don't even post the FR graphs for their reference line.
Those distortion measurements were taken at the NRC in Canada. It would be a practical impossibility for me to duplicate that test in our facility as we would need a true anechoic chamber (it is a complex measurement procedure)
I would like to be able to at least come close to duplicating that test, and that is something I do intend on working on in the future.
Maybe this is old news, but I just noticed for the SE models, more measurements/graphs have been added for:
Curtis, where ya' been? Those measurements were posted a LONG time ago :D
curtis
04-20-2007, 07:42 AM
I must be losin' it.
Have they been discussed on the forum already too?
bikeman
04-20-2007, 08:24 AM
I must be losin' it.
We've been meanin to speak to ya about that. :p
Have they been discussed on the forum already too?
No discussion. You gave the first heads up as far as I know.
David
drewface
04-20-2007, 09:11 AM
i think a discussion on the graphs would be interesting. i think i sort of understand what they are showing, but don't really have a very good idea of what they mean in terms of speaker quality.
GirgleMirt
04-20-2007, 03:54 PM
which one?
http://www.ascendacoustics.com/pages/products/speakers/cmt340m/cmt340mmeas.html
1st is FR, self explanatory. Depends on taste, I happen to think 100% flat from 20hz to 20khz is just perfect!
2nd, as graph says, 0 degree is green, 15 is yellow, 30 cyan, 45 red. Listening window is the average of those. vertical is vertical. As close as each other.
3rd. Impendance & electrical, impendance = ohms of speaker depending on frequency. Electrical, I dunno!
4th. Cumulative Spectral Decay. You want to see the waterfall drop as fast as possible (time in ms on right side).
If you compare the HTM200 and the 340SE, you'll see the HTM 'drag on' to like 1.96ms where the 340SE are almost gone by 1.21ms at 10khz and 1.8 at ~1khz, which indicates less... hmm.... distortion I guess you could say, maybe 'ringing'... In simple terms, the faster it drops, the better :)
More info in better terms (read davef's post on 1st link! btw, graphs there are for non-SE):
cumulative spectral decay, I was about to ask, but found this explanation by Dave midpage here :) thx! http://forum.ascendacoustics.com/showthread.php?t=856&page=2&pp=10&highlight=cumulative+spectral+decay
Other info: http://forum.ascendacoustics.com/showthread.php?t=978&highlight=cumulative+spectral+decay
drewface
04-20-2007, 04:47 PM
on the second graph, are the listening window and vertical response plots shifted down for easier reading, when they should be right on top of the four plots at the top of the graph?
thanks for those links, too. i pretty much knew what was being shown, but it's nice to have some concrete description of how it relates to sound and whatnot, even if the actual data being presented is easy to understand.
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