Hi,
I have a basic understanding on how to interpret waterfall plots but I haven't been able to find anything which explains how to tell whether the transient response of a driver is good or not. I think I'm ok with being able to spot resonances etc but what for instance is a good transient response for a mid base driver. I've attached a waterfall plot here for a 5" mid bass driver. Can someone comment on whether the transient response is good bad average 🙂
And what would be good, bad, average (relative to what this one is).
Sorry about the image quality, I think the highest time shown is about 1.95ms It's definitely under 2ms.
I guess the other thing is, Is it good that this driver seems to be pretty consitent from low Hz up to about 4000Hz (I'm assuming this is a desirable thing).
Also any links to sites that give a good explanation of how to interpret waterfall plots would be great.
Regards,
Tony.
I have a basic understanding on how to interpret waterfall plots but I haven't been able to find anything which explains how to tell whether the transient response of a driver is good or not. I think I'm ok with being able to spot resonances etc but what for instance is a good transient response for a mid base driver. I've attached a waterfall plot here for a 5" mid bass driver. Can someone comment on whether the transient response is good bad average 🙂
And what would be good, bad, average (relative to what this one is).
Sorry about the image quality, I think the highest time shown is about 1.95ms It's definitely under 2ms.
I guess the other thing is, Is it good that this driver seems to be pretty consitent from low Hz up to about 4000Hz (I'm assuming this is a desirable thing).
Also any links to sites that give a good explanation of how to interpret waterfall plots would be great.
Regards,
Tony.
Attachments
I think you'll get a better handle on transient response by looking at impulses or steps in the time domain. Waterfalls are more useful for spotting resonances and stored energy (though a high-resolution plot of impedance in the complex plane is even better. imo).
Hi Sy,
My beleif was that transient response was basically how quickly the driver can react to a sound input, and how quickly it stops producing the sound once the input is removed. Is that right? So basically a speaker with poor transient response will take a while to get up to speed so to speak and then also take a while to stop again, resulting in a muddy (ie unclear/ not detailed) sound.
I thought maybe the cumulative spectral decay graph would indicate at least the quickness of decay and provide some insight (but I don't have a baseline as to what is quick and what is slow). I'm just going of published stuff here not my own measurements.
I've heard of impulse and step response but haven't really read up on them, looks like it's time for that now too 🙂..... Not sure where I can get that data from though, is it something you can measure yourself? Bit hard if trying to find out before buying something though
I think I'm ok with spotting resonances, although I must admit the plot I attached does confuse me somewhat in the way it slopes to the right, most graphs I have seen the resonances come straight out at 90 degrees to the freq axis not cut across it at an angle like the one I showed.
Regards,
Tony.
My beleif was that transient response was basically how quickly the driver can react to a sound input, and how quickly it stops producing the sound once the input is removed. Is that right? So basically a speaker with poor transient response will take a while to get up to speed so to speak and then also take a while to stop again, resulting in a muddy (ie unclear/ not detailed) sound.
I thought maybe the cumulative spectral decay graph would indicate at least the quickness of decay and provide some insight (but I don't have a baseline as to what is quick and what is slow). I'm just going of published stuff here not my own measurements.
I've heard of impulse and step response but haven't really read up on them, looks like it's time for that now too 🙂..... Not sure where I can get that data from though, is it something you can measure yourself? Bit hard if trying to find out before buying something though
I think I'm ok with spotting resonances, although I must admit the plot I attached does confuse me somewhat in the way it slopes to the right, most graphs I have seen the resonances come straight out at 90 degrees to the freq axis not cut across it at an angle like the one I showed.
Regards,
Tony.
Tony, normally waterfall plots are derived from the impulse response. And an impulse is about as pure a transient as you'll find. Impulses can be gathered directly or by taking an autocorrelation of an MLS excitation. In English, you hit a bell with a hammer and see how it rings.
Interpreting the waterfalls is difficult- understanding how transform parameters affect the waterfall display is even tougher (the "slope" you're having trouble with is a perfect example). D'Appolito's book gives a fairly good explanation of what the plots are and aren't and how to interpret them.
Interpreting the waterfalls is difficult- understanding how transform parameters affect the waterfall display is even tougher (the "slope" you're having trouble with is a perfect example). D'Appolito's book gives a fairly good explanation of what the plots are and aren't and how to interpret them.
Thanks SY. I've seen Dappolitos book mentioned a bit, I'll have to keep an eye out for it!
I'm also going to have to get off my backside and buy some drivers, before I go nuts with too much theory 🙂
Regards,
Tony.
I'm also going to have to get off my backside and buy some drivers, before I go nuts with too much theory 🙂
Regards,
Tony.
Here's some waterfalls with time on an axis...
Check that transient response:
http://www.quadesl.com/madisound/sds_esl_impulse.gif
Sheldon
Check that transient response:
http://www.quadesl.com/madisound/sds_esl_impulse.gif
Sheldon
"My belief was that transient response was basically how quickly the driver can react to a sound input, and how quickly it stops producing the sound once the input is removed. Is that right?"
I believe this is exactly right.
Like You, I also do not know how quickly the graph ought to decay to indicate a musical speaker.
E-SPEAKERS has both step response and impulse response graphs of the Josef Manger driver at the bottom of this page http://www.e-speakers.com/products/manger.htm also a waterfall plot which You can use for comparison. This is an 8" Titanium membrane with 1.3Teslas of flux density. I think any mid cone or woofer which decays as quickly is apt to be a good one. Perhaps other catalogs have step or impulse plots for cones but I only remember seeing them for tweeters.
Another way to consider speed before buying a driver is to read the construction details. High power woofers with their huge heavy 3 and 4" voice coils tend to be slow to respond. These drivers also have rugged therefore heavy cones. Paper cones seem to be the fastest. Also stiff paper surrounds are said to make a faster speaker with foam coming next then neoprene rubber. I do not know where treated cloth surrounds fit in this. Higher flux density, like a Lowther, increases the response speed.
"I think I'm ok with spotting resonances, although I must admit the plot I attached does confuse me somewhat in the way it slopes to the right, most graphs I have seen the resonances come straight out at 90 degrees to the freq axis not cut across it at an angle like the one I showed."
I had a piano like that. When sustained one of the strings said wooowww. With the pitch rising with the passage of time. On this speaker I wonder if perhaps it is a vibration being excited in the metal basket.
I believe this is exactly right.
Like You, I also do not know how quickly the graph ought to decay to indicate a musical speaker.
E-SPEAKERS has both step response and impulse response graphs of the Josef Manger driver at the bottom of this page http://www.e-speakers.com/products/manger.htm also a waterfall plot which You can use for comparison. This is an 8" Titanium membrane with 1.3Teslas of flux density. I think any mid cone or woofer which decays as quickly is apt to be a good one. Perhaps other catalogs have step or impulse plots for cones but I only remember seeing them for tweeters.
Another way to consider speed before buying a driver is to read the construction details. High power woofers with their huge heavy 3 and 4" voice coils tend to be slow to respond. These drivers also have rugged therefore heavy cones. Paper cones seem to be the fastest. Also stiff paper surrounds are said to make a faster speaker with foam coming next then neoprene rubber. I do not know where treated cloth surrounds fit in this. Higher flux density, like a Lowther, increases the response speed.
"I think I'm ok with spotting resonances, although I must admit the plot I attached does confuse me somewhat in the way it slopes to the right, most graphs I have seen the resonances come straight out at 90 degrees to the freq axis not cut across it at an angle like the one I showed."
I had a piano like that. When sustained one of the strings said wooowww. With the pitch rising with the passage of time. On this speaker I wonder if perhaps it is a vibration being excited in the metal basket.
Thanks Brian,
Thats a very interesting driver (and at the price I guess it would want to be!)
I think I have a tendency to over research before making a purchase decision 🙂 (at least when there is a reasonable amount of money involved).
I think you are probably right about comparing the decay on a known fast driver with another, I think I should stop worrying and just get on an buy it 🙂
You might be onto something with your piano analogy too, perhaps the freq changes somewhat as the sound decays, hadn't thought of it like that.
Regards,
Tony.
Thats a very interesting driver (and at the price I guess it would want to be!)
I think I have a tendency to over research before making a purchase decision 🙂 (at least when there is a reasonable amount of money involved).
I think you are probably right about comparing the decay on a known fast driver with another, I think I should stop worrying and just get on an buy it 🙂
You might be onto something with your piano analogy too, perhaps the freq changes somewhat as the sound decays, hadn't thought of it like that.
Regards,
Tony.
Honestly, one of the major influences in the choice of drivers for me is hearing a speaker I really like, then noting what the drivers are. There's a lot that the data sheets don't and can't tell you.
SY said:
I know what you mean. I have seen some nice specs and then heard the speakers and really not liked them. I think though that I'm going to be hard pressed to find some to listen to. The driver in question is a morel MW-144...... I know there are a few high end speakers made here in aus which use morel drivers but I don't know if any are using this particular driver. Based on specs alone though it seems to be a good fit for what I want to achieve. price wise its pretty expensive (especially for an MTM seup) but I guess If I end up not liking it I can always try and sell them to someone who does 🙂
Regards,
Tony.
Another indicator of speed is said to be efficiency. It has been claimed that the same qualities which make a driver efficient (i.e. great loudness from small power) also make it quick. Principally this seems to be light weight moving parts.
efficiency = speed
Wow, that means my JBL 18 inchers are fast!
Nope, that's just another of those old audiophile tales.
Wow, that means my JBL 18 inchers are fast!
Nope, that's just another of those old audiophile tales.
Hello SY,
A big speaker gets much of it's loudness from it's size. I neglected to take size into consideration. If I changed my earlier post to read: "the more efficient speaker of a given size is the quickest in that size" would that be generally accurate?
A big speaker gets much of it's loudness from it's size. I neglected to take size into consideration. If I changed my earlier post to read: "the more efficient speaker of a given size is the quickest in that size" would that be generally accurate?
Back to the original question. The decay response of this driver appears to be average, and that is poor. I agree, it is hard to see the details in the attachment, and it is hard to read the frequency scale across the time of the waterfall.
"Nevertheless," what we would call the typical frequency response, the line all the way at the back, appears to be rolling off below 1 kHz. Peak output is at 1 kHz, then falls and rises again before 2 kHz. There is also another peak just before high frequency roll-off. All of these peaks are resonance induced. They persist into the late decay. Also, break-up above 4 to 10 KHz (can't really be sure where it begins) is much more rough than I would like to see.
As to how to interpret. A fast driver is going to have extended high frequency response. A non resonant driver will show a fast and even decay response. This driver does not do either. And it is not atypical of midrange drivers. If this driver's output dies as fast and hard as it appears, it is also going to show a slow onset response to an impulse or step response test. It will also ring like a bell based upon the several long mid-range decay "bumps." Again, none of this is atypical for so called "mid-range" drivers.
I have made two long postings about "Testing and Loudspeaker Design" and "Simple MFB Woofer Project" to this forum. In both I talk about transient testing and what I like to see in the bode plot transforms of impulse responses. If you wish to strike out into radical acoustical measurement testing and interpretation, you might get a kick out of reading through my dribble.
There is even more on my Web site at http://madspeaker.com/
This is a commercial site, so as an ethical person I want to warn you of this fact.
Tony, I wish you the best of luck. You have taken on a very difficult task. If you read the various postings out there, you will find scathing reviews of the errors of commerical loudspeakers produced by companies with long and impecable reputations who have invested hundreds of thousands of dollars into R&D. Despite this investment, they still fail to produce listenable loudspeakers. But just because they failed, does not mean you cannot succeed. Despite all the science we have available today, there is still a great deal of art and craft in loudspeaker design.
Mark
"Nevertheless," what we would call the typical frequency response, the line all the way at the back, appears to be rolling off below 1 kHz. Peak output is at 1 kHz, then falls and rises again before 2 kHz. There is also another peak just before high frequency roll-off. All of these peaks are resonance induced. They persist into the late decay. Also, break-up above 4 to 10 KHz (can't really be sure where it begins) is much more rough than I would like to see.
As to how to interpret. A fast driver is going to have extended high frequency response. A non resonant driver will show a fast and even decay response. This driver does not do either. And it is not atypical of midrange drivers. If this driver's output dies as fast and hard as it appears, it is also going to show a slow onset response to an impulse or step response test. It will also ring like a bell based upon the several long mid-range decay "bumps." Again, none of this is atypical for so called "mid-range" drivers.
I have made two long postings about "Testing and Loudspeaker Design" and "Simple MFB Woofer Project" to this forum. In both I talk about transient testing and what I like to see in the bode plot transforms of impulse responses. If you wish to strike out into radical acoustical measurement testing and interpretation, you might get a kick out of reading through my dribble.
There is even more on my Web site at http://madspeaker.com/
This is a commercial site, so as an ethical person I want to warn you of this fact.
Tony, I wish you the best of luck. You have taken on a very difficult task. If you read the various postings out there, you will find scathing reviews of the errors of commerical loudspeakers produced by companies with long and impecable reputations who have invested hundreds of thousands of dollars into R&D. Despite this investment, they still fail to produce listenable loudspeakers. But just because they failed, does not mean you cannot succeed. Despite all the science we have available today, there is still a great deal of art and craft in loudspeaker design.
Mark
Brian, I don't know; I haven't really surveyed, say, all the 12" woofers to see if there's a real correlation or not.
For example, the fastest risetimes I've seen in 12 inchers is the old Dynaudio 30W54, yet they're less efficient than the 30W100, which has a slower rise time. Exceptions? Maybe. (Does the rise-time really matter for a woofer? Probably not.)
I'll have to go back to my notes and compare the rise times of the 6" Audax pro driver (something like 100 db/2.83V/1M) and the Dynaudio 17W75EXT (something like 86 dB/2.83V/1M) and see if they correlate with this "rule."
For example, the fastest risetimes I've seen in 12 inchers is the old Dynaudio 30W54, yet they're less efficient than the 30W100, which has a slower rise time. Exceptions? Maybe. (Does the rise-time really matter for a woofer? Probably not.)
I'll have to go back to my notes and compare the rise times of the 6" Audax pro driver (something like 100 db/2.83V/1M) and the Dynaudio 17W75EXT (something like 86 dB/2.83V/1M) and see if they correlate with this "rule."
Thanks for the analysis Mark. I went back to morel europes site and compared the freq response graph with the waterfall plot, and there are some major incosistancies! the highs look to sort of match, but very different below 1000Hz. Could be some dodgyness going on.
Thanks for the well wishes. My current speakers were hobbled together over the years, with very little knowledge, but they still sound better than most peoples speakers that I know, and a damn site better than quite a few supposedly good commercial speakers I have heard as well. Maybe I'm just lucky 🙂. The only thing I will be disapointed about when I make my next project will be if it doesn't sound better than the existing speakers, and knowing the short commings in them, I think it will be hard for them not to be better 🙂
If I start out with low expectations, then Hopefully I won't be dissapointed!!!!!
The only thing that really worries me is whether I'm going to match the clarity of my Phillips dome midranges. They're old, but sound so far superior to any cone based midrange I have ever used and I worry a bit that I'm not going to match them.
Admittedly I've only had cheap polycone mids in the past, so I hope that by buying something "better" I won't be dissapointed.
Regards,
Tony.
Thanks for the well wishes. My current speakers were hobbled together over the years, with very little knowledge, but they still sound better than most peoples speakers that I know, and a damn site better than quite a few supposedly good commercial speakers I have heard as well. Maybe I'm just lucky 🙂. The only thing I will be disapointed about when I make my next project will be if it doesn't sound better than the existing speakers, and knowing the short commings in them, I think it will be hard for them not to be better 🙂
If I start out with low expectations, then Hopefully I won't be dissapointed!!!!!
The only thing that really worries me is whether I'm going to match the clarity of my Phillips dome midranges. They're old, but sound so far superior to any cone based midrange I have ever used and I worry a bit that I'm not going to match them.
Admittedly I've only had cheap polycone mids in the past, so I hope that by buying something "better" I won't be dissapointed.
Regards,
Tony.
hiya!
ive got some late 70s vintage philips tweeter+2x4" mid per channel !
il have some pics soon tooo
the tweeter has a little fuzzy thing infront of it 😛
(no i havent poked it to see whats behind there)🙄
u can sorta see through it.
my dad bought them in Auckland and hardly used them
🙂
By the end of the 70ies those were quite fine tweeters at a very interesting price.
Regards
Charles
Regards
Charles
- Status
- Not open for further replies.