dlr said:
(..I should have also added *shape* as a caveat.)
What contradiction?
I certainly don't think *all* drivers will perform (in total) better with foam surrounds. Certainly drivers with stiff straight profile cones creating dominate in-band resonances will overall NOT perform better with foam (vs. rubber). (..that's why I added the caveats.) As an industry average however, they would be more eff. if they did.
As an interesting "aside" to this discussion:
I had always presumed that the "correct" role of a surround was to ONLY:
1. keep out-of-phase sound from leaking through to the front (i.e. baffle duty), and
2. keep the vc centered during excursion.
NOT provide cone edge damping. Nor alter compliance.
lrntglls said:
Probably less *apparent* distortion. Measured distortion with a traditional amp.. I doubt it.
BTW.. If I had the space or the time this particular driver would be my number one choice for a radial mid-range in a "desert island" system. (..with the "whizer" removed though.)
http://www.diyaudio.com/forums/showthread.php?s=&threadid=135419
gedlee said:
The only audiophiles I know of who are professionals as audiophiles are: writers.
For the rest - its a hobby. Does this particular hobby need "data" beyond personal listening? In fact, might not the hobby be *more* enjoyable without it?
(..of course this forum isn't exactly limited to this particular hobby, thankfully. However, this forum *does* include this activity - also thankfully.)
ScottG said:(..I should have also added *shape* as a caveat.)
What contradiction?
The description was about the "sound" of the surround, then the caveat of the "partnering" diaphragm. The original claim (not yours) was of a "sound" uniquely applicable to the surround irrespective of the diaphragm. I simply reject that latter claim and still do.
miamiphoto said:
The Ariel was a good speaker of the day, but that was back in the early Nineties, and the drivers are no longer available. There were many compromises, most of all dynamically, to keep it small and relatively simple. But the measured response in the time domain was pretty good, and I'm aiming for that for the new speaker.
Right now I'm reading MBK's "Adventures in Cardioid" thread very carefully, since I plan to experiment with resistive-mesh baffles for the 414 and/or 12NDA520.
If you were going to make a "new" Ariel with new drivers, the JA8008 would be a candidate, along with the Skaaning/Audio Technology drivers. I've heard the Skaaning drivers, and they have the same design characteristics as the original drivers in the Ariel - smooth rolloffs, usable with reasonably simple crossovers, and good subjective qualities. For all I know, Ejvind Skaaning designed the Vifa P13WH-00-08 and the Scan-Speak D2905/9000 - they certainly sound similar to the Skaaning drivers, while Scan-Speak, Vifa, and Seas have moved in a different direction.
But this would require an all-new crossover, a new transmission line, and after all that, it would be a new system.
gedlee said:
From what I have seen in measurements of midwoofers(for instance in the B&W paper), the first surround resonance typically occcurs significantly LOWER in frequency than the actual cone breakup .
In which case you would try to cure an evil (modal waves in the cone, more or less damped in the surround) by introducing a problem lower in frequency by the surround itself - and therefore restrict the "useable" pistonic range of the driver upwards in frequency! (at least if keeping the surround resonance out of the bandpass is required)
This might make sense for a bass driver, but not for the typical midwoofer covering the range to 2-3 kHz or even more (which I know you dismiss as a design option anyway). So for the way you design speakers (crossing as low as 1kHz) the surround indeed probably plays no audible role.
FYI the P13WH00-8 and the ScanSpeak 2905/9300 and 9500 are still available from Madiosund.
http://www.madisound.com/catalog/product_info.php?manufacturers_id=153&products_id=1105
http://www.madisound.com/catalog/product_info.php?manufacturers_id=153&products_id=1105
"surround sound"
Thinking about it for some time - two things got heavily mixed :
- One is the discussion of "surround sound"
- The other topic ist the discussion about the amount of “science in speaker design / Who needs data when we have audiophiles”
Regarding the second – I admire the effort some make to look at speraker design from a mere scientific point of view – but personally I’m not sold to it – though contributing to issues of my interest from time to time.
There is either the possibility to pretend (anything already is scientifically proven) – or – to end up with an average design in its best meaning (approved by scientific statistics on whats relevant or not for the audiophile crowd) if you claim your speaker is pure science.
I admit - this becomes a endless debate not worth the time.
Regarding the first
There is a difference in points of view that can be broken down to
- discussing the underlaying roles of physics / mechanics / kinematiks (as is my approach)
- and on the other hand the superordinate view (if this is the right term) of "termination" applying
For example if I analyse
“Termination of the cone is not just an important thing to consider, it is the primary thing to consider.
... If it terminates properly it will move in such a way that it acts as an extension of the cone. It goes back to mechanical impedance of the termination.”
- first what comes into my mind is to ask about “termination” itself.
As to my knowledge “termination” originates from electronics where it *precisely* describes wave reflecting issues of lines and how to handle 'em.
The important thing to notice here is that *perfect* termination in electronics can be done – with no adverse effects whatsoever.
Some like to go into generalisation (as it *sometimes * can make things easier) but as for any science we first have to ask about the limitations this generalisation is valid for.
In the case of transferring the term "termination" to mechanics I doubt it
- either keeps its *precise* meaning
- or simply is limited to a "as if" similarity
If we go back to the recent discussion about the issue of minimum phase behaviour of drivers I asked JohnK if he thinks he (we) could equalize an empty boxed speaker as to the same sonic result (with regard to box resonancies) as a stuffed one – he didn't confirm.
I took it as the minimum phase bahaviour of speakers is limited to some extent – meaning it is – widely – acting *as if* but not precisely.
Same at the topic of surround sound IMO.
If we only think in terms of "termination" and don't go one layer deeper we would not do justice to the sonic differences some of us (not only me, mind you) are able to spot.
Mechanic termination (form internal material dampening) might be a desire and aim but in fact does not exist at a closer look IMO
What I have pointed out about adverse effects - velocity dampening versus dampening by friction – clearly tells us more about the story of "surround sound" - and there is even more that could be added .
Michael
Thinking about it for some time - two things got heavily mixed :
- One is the discussion of "surround sound"
- The other topic ist the discussion about the amount of “science in speaker design / Who needs data when we have audiophiles”
Regarding the second – I admire the effort some make to look at speraker design from a mere scientific point of view – but personally I’m not sold to it – though contributing to issues of my interest from time to time.
There is either the possibility to pretend (anything already is scientifically proven) – or – to end up with an average design in its best meaning (approved by scientific statistics on whats relevant or not for the audiophile crowd) if you claim your speaker is pure science.
I admit - this becomes a endless debate not worth the time.
Regarding the first
There is a difference in points of view that can be broken down to
- discussing the underlaying roles of physics / mechanics / kinematiks (as is my approach)
- and on the other hand the superordinate view (if this is the right term) of "termination" applying
For example if I analyse
“Termination of the cone is not just an important thing to consider, it is the primary thing to consider.
... If it terminates properly it will move in such a way that it acts as an extension of the cone. It goes back to mechanical impedance of the termination.”
- first what comes into my mind is to ask about “termination” itself.
As to my knowledge “termination” originates from electronics where it *precisely* describes wave reflecting issues of lines and how to handle 'em.
The important thing to notice here is that *perfect* termination in electronics can be done – with no adverse effects whatsoever.
Some like to go into generalisation (as it *sometimes * can make things easier) but as for any science we first have to ask about the limitations this generalisation is valid for.
In the case of transferring the term "termination" to mechanics I doubt it
- either keeps its *precise* meaning
- or simply is limited to a "as if" similarity
If we go back to the recent discussion about the issue of minimum phase behaviour of drivers I asked JohnK if he thinks he (we) could equalize an empty boxed speaker as to the same sonic result (with regard to box resonancies) as a stuffed one – he didn't confirm.
I took it as the minimum phase bahaviour of speakers is limited to some extent – meaning it is – widely – acting *as if* but not precisely.
Same at the topic of surround sound IMO.
If we only think in terms of "termination" and don't go one layer deeper we would not do justice to the sonic differences some of us (not only me, mind you) are able to spot.
Mechanic termination (form internal material dampening) might be a desire and aim but in fact does not exist at a closer look IMO
What I have pointed out about adverse effects - velocity dampening versus dampening by friction – clearly tells us more about the story of "surround sound" - and there is even more that could be added .
Michael
Just my 2 cents.
I have just got a new soundcard Native Instrument's Session IO with a built-in mic preamp and this is giving me a new level of accuracy and ease in measurements. I can highly recommend this soundcard to anyone. Gone are my M-Audio transit card with the Behringer U802 mixer used as a microphone preamp. Now things are much better. My 2 years of search for a soundcard is finally over.
So a new round of measurements started this morning.
Cone Transparency - This is in response to some of the discussions a week or two ago. Cones are "transparent"! Without damping I measured nearfield at the exit of the back of the U-frame housing the ScanSpeak 10" revolator 8861T00 a 11dB 1/4 wavelength resonance peak of the U-frame. In front of the speaker cone it was measured as a 6dB peak (and a bit of a null).
But even with reasonable amount of damping (sheep wool batts), the U-frame 1/4 wavelength resonance was completely gone without any trace and the response was very "flat".
So I am pleased. There is nothing to worry about the U-frame 1/4 wavelength resonance!
This leads me to believe that appropreiate damping is extremely important and it kills many problems associated with the boxes / U-frames / open back boxes. But I have to say how to damp the resonances with damping material is a work of art.
Now I am going back to my measurements.
Regards,
Bill
I have just got a new soundcard Native Instrument's Session IO with a built-in mic preamp and this is giving me a new level of accuracy and ease in measurements. I can highly recommend this soundcard to anyone. Gone are my M-Audio transit card with the Behringer U802 mixer used as a microphone preamp. Now things are much better. My 2 years of search for a soundcard is finally over.
So a new round of measurements started this morning.
Cone Transparency - This is in response to some of the discussions a week or two ago. Cones are "transparent"! Without damping I measured nearfield at the exit of the back of the U-frame housing the ScanSpeak 10" revolator 8861T00 a 11dB 1/4 wavelength resonance peak of the U-frame. In front of the speaker cone it was measured as a 6dB peak (and a bit of a null).
But even with reasonable amount of damping (sheep wool batts), the U-frame 1/4 wavelength resonance was completely gone without any trace and the response was very "flat".
So I am pleased. There is nothing to worry about the U-frame 1/4 wavelength resonance!
This leads me to believe that appropreiate damping is extremely important and it kills many problems associated with the boxes / U-frames / open back boxes. But I have to say how to damp the resonances with damping material is a work of art.
Now I am going back to my measurements.
Regards,
Bill
Perhaps I was too quick recommending the NI Session IO (I paid just over AUD$300 for it in Sydney but don't forget it has a built-in mic preamp with phamtom mode and it should work much better than a U802).
I was able to get very good impedance measurements as well as nearfield measurements this morning. However, I was unable to get the impulse response. I am still working on it.
This may be due to the fact that the left and right channels are swapped and I am wondering if Speaker Workshop would hard code the channels for the impulse (but not nearfield and others).
I was able to get very good impedance measurements as well as nearfield measurements this morning. However, I was unable to get the impulse response. I am still working on it.
This may be due to the fact that the left and right channels are swapped and I am wondering if Speaker Workshop would hard code the channels for the impulse (but not nearfield and others).
I have now got the Native Instrument Seesion IO USB soundcard working. I initially set the latency to be 24ms which was unnecessary. Removed the latency and the impulse arrived at 5 seconds. This is strange but it is a fact. If you use this soundcard, you need to swap the left and right channel through the software.
I have destroyed 2 M-Audio Transit USB soundcard, and returned the third one, replaced it with this soundcard. The M-Audio transit had output DC offset of over 1VDC and burned the fuses of my power amps a few times.
I have also tried other cheap computer soundcards and found the noise to be very high and the channel differences on the high side causing phase errors. The result was not satisfactory.
You can google the site and find the spec. The spec is much higher than most soundcard. I measured the output DC offset to be 0.1mV on one channel and 2.3mV on the other, which is typical of opamp DC offset.
Yes it is expensive and it took me a while to decide to give it a go, having no other choice. But considering the time I have spent on trying various soundcards the cost would be much more than 300+ dollars.
I have destroyed 2 M-Audio Transit USB soundcard, and returned the third one, replaced it with this soundcard. The M-Audio transit had output DC offset of over 1VDC and burned the fuses of my power amps a few times.
I have also tried other cheap computer soundcards and found the noise to be very high and the channel differences on the high side causing phase errors. The result was not satisfactory.
You can google the site and find the spec. The spec is much higher than most soundcard. I measured the output DC offset to be 0.1mV on one channel and 2.3mV on the other, which is typical of opamp DC offset.
Yes it is expensive and it took me a while to decide to give it a go, having no other choice. But considering the time I have spent on trying various soundcards the cost would be much more than 300+ dollars.