I think that it is the secondary mode of 25' length that is there. It shows on every basspeaker I measure in the room also on my Magnepans 1.6.
Yes I was a bit surprised over the Alphas clean measurement and gentle roll off. In fact it is quite listenable as fullrange. But perhaps one shouldn't have been surprised. I think that Hawthorne's Silver Iris is not so much more than an Alpha15 adapted to a Beta12-CX magnet and the Iris is crossed somewhere 2.5-3 kHz.
/Erling
Yes I was a bit surprised over the Alphas clean measurement and gentle roll off. In fact it is quite listenable as fullrange. But perhaps one shouldn't have been surprised. I think that Hawthorne's Silver Iris is not so much more than an Alpha15 adapted to a Beta12-CX magnet and the Iris is crossed somewhere 2.5-3 kHz.
/Erling
Carver Amazing Loudspeaker Low Frequency System
Guys,
I created the Carver Amazing woofer system and Large Area Ribbon (co-authored with David Graebener) for Bob Carver in the mid 1980's as a consultant to Carver Corporation and was VP of Research and Development at Carver in the 1990s. I would be glad to answer any questions anyone has about these devices.
One question that was asked was whether the Amazings had a high or low Qms. The Qms was quite high, we attempted to achieve a Qms of nearly 10, which is required if one is going to end up with a Qt of much greater than 2 and still maintain reasonable efficiency.
The trick is to be able to maintain 'linear' Qms. One of the big problems we found early in the development of the Hi-Q open baffle was that many of the Hi-Q drivers have Qms values that change depending on level. This non-linear Qms causes a non-linear Qts, which causes a non-linear frequency response with level...i.e. compression/distortion. This Qms modulation is one of the main reasons that some have found higher Qts drivers to sound bad. It’s is not the higher Qts, but the Qms -> Qts nonlinearity that causes the poor sound quality. Proper Qts match to baffle cut-off frequency will perform quite perfectly, even for higher Qt values if the resulting frequency response is flat and the Qt value is maintained at all listening levels.
The Amazing suspension components, spider and surround, took nearly 9 months to work through the design problems to chase out the non-linearities. No one had optimized high-Q woofers previous to the Amazings so the driver vendors were not able to help. We had to drive the component development ourselves. It was hard to get spiders with low enough damping (they actually call them dampers in Japan) to achieve high-Q and then it was even more difficult to develop spiders and surrounds that maintained constant damping.
Okay, that is probably more than what anyone wanted to know on that subject, but I felt it was important to start getting past this myth that “high-Q drivers are bad”. It is a systems approach. High-Q is not inherently bad, but ‘mismatched’-Q is. A high-Q driver is appropriate when matched to a ‘low-Q baffle’, just as a Low-Q driver is appropriate to match to a ‘high-Q’ Helmholtz enclosure.
The original Amazings had even higher Qts and lower Fs than the later Series. As someone in the forum suggested, lower Fs requires higher-Q, but this becomes problematic. For a fixed baffle cutoff frequency, with the standard 6 dB/octave high pass characteristic from cut-off down to the resonant frequency, the ideal high-Q gain would match that first order slope over the bandwidth from cutoff to fs. Unfortunately, the 12 dB of gain we needed in the original Amazings to achieve reference level at the Fs of 20 Hz required a Qts of about 4. This created a narrow band peak that doesn’t match the smooth, 6 dB roll-off slope of the open baffle. Because of this we had to use some shaping networks to smooth things out from 25 Hz to 100 Hz. We ended up with a fairly smooth response with a peak at 20 Hz and Fc at 17 or 18 Hz.
The later Amazings had a new lower mass paper cone woofer to replace the heavier honeycomb devices in the originals. We were able to get the moving mass down to less than 15 grams, which is quite low for a 12” woofer, but required for getting decent efficiency.
The Fs was raised to 30 Hz and the Qts was lowered to a value between 2.5 and 3. This worked much better in matching the Fs, Qts, and baffle Fc to get a smoother response and much higher efficiency.
I’ll stop here. Hopefully this info is of some interest to the group. If not, I apologize for hi-jacking your space.
Warm regards,
- Jim Croft
Guys,
I created the Carver Amazing woofer system and Large Area Ribbon (co-authored with David Graebener) for Bob Carver in the mid 1980's as a consultant to Carver Corporation and was VP of Research and Development at Carver in the 1990s. I would be glad to answer any questions anyone has about these devices.
One question that was asked was whether the Amazings had a high or low Qms. The Qms was quite high, we attempted to achieve a Qms of nearly 10, which is required if one is going to end up with a Qt of much greater than 2 and still maintain reasonable efficiency.
The trick is to be able to maintain 'linear' Qms. One of the big problems we found early in the development of the Hi-Q open baffle was that many of the Hi-Q drivers have Qms values that change depending on level. This non-linear Qms causes a non-linear Qts, which causes a non-linear frequency response with level...i.e. compression/distortion. This Qms modulation is one of the main reasons that some have found higher Qts drivers to sound bad. It’s is not the higher Qts, but the Qms -> Qts nonlinearity that causes the poor sound quality. Proper Qts match to baffle cut-off frequency will perform quite perfectly, even for higher Qt values if the resulting frequency response is flat and the Qt value is maintained at all listening levels.
The Amazing suspension components, spider and surround, took nearly 9 months to work through the design problems to chase out the non-linearities. No one had optimized high-Q woofers previous to the Amazings so the driver vendors were not able to help. We had to drive the component development ourselves. It was hard to get spiders with low enough damping (they actually call them dampers in Japan) to achieve high-Q and then it was even more difficult to develop spiders and surrounds that maintained constant damping.
Okay, that is probably more than what anyone wanted to know on that subject, but I felt it was important to start getting past this myth that “high-Q drivers are bad”. It is a systems approach. High-Q is not inherently bad, but ‘mismatched’-Q is. A high-Q driver is appropriate when matched to a ‘low-Q baffle’, just as a Low-Q driver is appropriate to match to a ‘high-Q’ Helmholtz enclosure.
The original Amazings had even higher Qts and lower Fs than the later Series. As someone in the forum suggested, lower Fs requires higher-Q, but this becomes problematic. For a fixed baffle cutoff frequency, with the standard 6 dB/octave high pass characteristic from cut-off down to the resonant frequency, the ideal high-Q gain would match that first order slope over the bandwidth from cutoff to fs. Unfortunately, the 12 dB of gain we needed in the original Amazings to achieve reference level at the Fs of 20 Hz required a Qts of about 4. This created a narrow band peak that doesn’t match the smooth, 6 dB roll-off slope of the open baffle. Because of this we had to use some shaping networks to smooth things out from 25 Hz to 100 Hz. We ended up with a fairly smooth response with a peak at 20 Hz and Fc at 17 or 18 Hz.
The later Amazings had a new lower mass paper cone woofer to replace the heavier honeycomb devices in the originals. We were able to get the moving mass down to less than 15 grams, which is quite low for a 12” woofer, but required for getting decent efficiency.
The Fs was raised to 30 Hz and the Qts was lowered to a value between 2.5 and 3. This worked much better in matching the Fs, Qts, and baffle Fc to get a smoother response and much higher efficiency.
I’ll stop here. Hopefully this info is of some interest to the group. If not, I apologize for hi-jacking your space.
Warm regards,
- Jim Croft
Re: Carver Amazing Loudspeaker Low Frequency System
Don't apologize, post more often!
With these speakers being designed some time within a couple years of my birth, they're a bit before my time. I've seen them around many times, but not in person, and obviously never heard them. They do interest me though. Just to confirm, there's no way possible to get these drivers anymore?
Any similar high-Q woofers AFTER the Amazings that you're aware of? Rather, any linear Q woofers like those used in the Amazings that are currently available? Highly doubtful, but thought I'd ask anyway.
Thanks again for posting.. you've provided a lot of valuable answers to many questions in that single post.
I guess you won't see this if you don't check back, but if you do.. ^
JamesCroft said:
Don't apologize, post more often!
With these speakers being designed some time within a couple years of my birth, they're a bit before my time. I've seen them around many times, but not in person, and obviously never heard them. They do interest me though. Just to confirm, there's no way possible to get these drivers anymore?
JamesCroft said:
Any similar high-Q woofers AFTER the Amazings that you're aware of? Rather, any linear Q woofers like those used in the Amazings that are currently available? Highly doubtful, but thought I'd ask anyway.
Thanks again for posting.. you've provided a lot of valuable answers to many questions in that single post.
I guess you won't see this if you don't check back, but if you do.. ^
Hi Jim,
Your post is most interesting and illustrates a path quite different to that taken by current manufacturers as they went on to develop 'loud'speaker drivers which could withstand SS power.
I am one who does not like high Qes drivers, though this is quite different to high Qms!
A low Qes can control a high or slightly variable Qms whereas a high Qes cannot. Thus a high Qes driver can be louder at LF when driven by steady sines, yet still not be as able to accurately control and reproduce LF dynamics. We can electrically EQ/modify the response of a low Qes driver, but the higher Qes types retain a mass related 'momentum' of their own. You did well with <15g for a 12" driver.
Our sense of LF comes from harmonics which are above the resonant frequency range, thus we can recognise and enjoy LF even when the fundamental SPLs are disproportionate or phase shifted, but when the LF is well controlled there is yet another dimension to music and any ambience recorded with it.
Cheers .......... Graham.
Your post is most interesting and illustrates a path quite different to that taken by current manufacturers as they went on to develop 'loud'speaker drivers which could withstand SS power.
I am one who does not like high Qes drivers, though this is quite different to high Qms!
A low Qes can control a high or slightly variable Qms whereas a high Qes cannot. Thus a high Qes driver can be louder at LF when driven by steady sines, yet still not be as able to accurately control and reproduce LF dynamics. We can electrically EQ/modify the response of a low Qes driver, but the higher Qes types retain a mass related 'momentum' of their own. You did well with <15g for a 12" driver.
Our sense of LF comes from harmonics which are above the resonant frequency range, thus we can recognise and enjoy LF even when the fundamental SPLs are disproportionate or phase shifted, but when the LF is well controlled there is yet another dimension to music and any ambience recorded with it.
Cheers .......... Graham.
Re: Re: Carver Amazing Loudspeaker Low Frequency System
Thank you to everyone for the kind reception.
No, unfortunately, these drivers are not available. The nature of such a narrowly optimized design is that they are actually quite awful in any application other than that of a very specific open baffle design, such as the Amazings. It wouldn't be a very profitable venture for a vendor to offer them.
Also, I am not aware of any off the shelf drivers that are truly ideal for open baffle design.
Again, it is such a specialized device, with criteria that must be so carefully context matched as a system, that I don't think it is easy to define a generalized unit. Some have partially correct criteria and then miss the mark in other ways, and some get a different set of specs correct, only to still miss the complete picture.
A driver like the Eminence Alpha 15 is fairly okay, as a generalized all purpose unit, and it maintains decent linearity of Q over its full range of excursion, but that is partly because it has a very limited X-max capability in the first place. As long as one operates it within about +/-3 mm then it will perform well, and that is workable partly because it doesn't go very low with an Fs of 41 Hz. Its Qt of 1.25 is the optimal Q that Ray Newman specified in his 1980 AES paper on open baffle design, which for this high Fs and a reasonable baffle size is an okay value, but doesn't begin to push the limits of what one can achieve with an optimized open baffle design.
Most units with higher Qts exist, not by way of attempting optimal design, but merely for economical reasons...Cheap drivers through the use of small magnets.
Wish I had a better answer for you, but there just isn't much development in this arena. The transducer manufacturers that DO offer something useful for OB designs, still don't seem to understand what the ideal criteria would be, since this is usually not their primary area of application expertise.
I am working on a modern, updated version of the open baffle concept and am currently surveying available transducers. If I find any of great value for OB applications, I'll post the results. I am starting a development project with a couple vendors in parallel, with the assumption that I won't be finding what I need as an off the shelf device.
All the best,
Jim C.
BHTX said:
Don't apologize, post more often!
With these speakers being designed some time within a couple years of my birth, they're a bit before my time. I've seen them around many times, but not in person, and obviously never heard them. They do interest me though. Just to confirm, there's no way possible to get these drivers anymore?
Any similar high-Q woofers AFTER the Amazings that you're aware of? Rather, any linear Q woofers like those used in the Amazings that are currently available? Highly doubtful, but thought I'd ask anyway.
Thanks again for posting.. you've provided a lot of valuable answers to many questions in that single post.
I guess you won't see this if you don't check back, but if you do.. ^
Thank you to everyone for the kind reception.
No, unfortunately, these drivers are not available. The nature of such a narrowly optimized design is that they are actually quite awful in any application other than that of a very specific open baffle design, such as the Amazings. It wouldn't be a very profitable venture for a vendor to offer them.
Also, I am not aware of any off the shelf drivers that are truly ideal for open baffle design.
Again, it is such a specialized device, with criteria that must be so carefully context matched as a system, that I don't think it is easy to define a generalized unit. Some have partially correct criteria and then miss the mark in other ways, and some get a different set of specs correct, only to still miss the complete picture.
A driver like the Eminence Alpha 15 is fairly okay, as a generalized all purpose unit, and it maintains decent linearity of Q over its full range of excursion, but that is partly because it has a very limited X-max capability in the first place. As long as one operates it within about +/-3 mm then it will perform well, and that is workable partly because it doesn't go very low with an Fs of 41 Hz. Its Qt of 1.25 is the optimal Q that Ray Newman specified in his 1980 AES paper on open baffle design, which for this high Fs and a reasonable baffle size is an okay value, but doesn't begin to push the limits of what one can achieve with an optimized open baffle design.
Most units with higher Qts exist, not by way of attempting optimal design, but merely for economical reasons...Cheap drivers through the use of small magnets.
Wish I had a better answer for you, but there just isn't much development in this arena. The transducer manufacturers that DO offer something useful for OB designs, still don't seem to understand what the ideal criteria would be, since this is usually not their primary area of application expertise.
I am working on a modern, updated version of the open baffle concept and am currently surveying available transducers. If I find any of great value for OB applications, I'll post the results. I am starting a development project with a couple vendors in parallel, with the assumption that I won't be finding what I need as an off the shelf device.
All the best,
Jim C.
Graham Maynard said:
Graham, I'm not sure what you are referring to here. The Carver Amazings were developed with, and for use with, very high powered amplifiers. A 500 watt per channel amp was used throughout the development cycle. While a single woofer can't handle that much power, the four woofer voice coils in parallel were able to dissipate significant program power.
But, maybe you were making a different point.
Even though it is true that low Qes drivers are much more tolerant of Qms nonlinearity, that does not automatically suggest that a properly designed transducer and system utilizing a high Qts driver cannot be driven as loud as a low Qts driver and still maintain control and accurately reproduce dynamics. But, and it is a big BUT, one has to control ALL the variables much more carefully with a high Qts device.
To properly develop a system with high Q components takes much more effort than most are willing to put into a design effort. Additionally, one has to be very careful in making judgements about the limitations of particular audio components and characteristic. It is the context in which something is used that matters most, but the rigor it takes to get to the truth of these matters is so very difficult, that very few folks are willing to do the work.
To validate the low Qts driver application, I had to do extensive work in comparing a high Qts driver based dipole to a low Qts driver in an enclosure and match the high and low pass, and passband characteristics, and other parameters...essentially the complete transfer function. Then and only then, can one truly determine whether a high Qts transducer based system can equal a low Qts one.
I understand the impression that high Qts drivers sound worse, because they do in over 90% of their applications. System alignments are critical in high Qts OB systems, very much like system alignments are critical in vented systems that use low Qts drivers in high Qb enclosures. Most of those sound bad too.
The tolerance for mismatching parameters is inversely proportional to the Q of the key element of an electro-acoustical system. In general, I don't like high Qes drivers either, but not because they are inherently inferior, but because they are so darn difficult to match to the system. But, if one has the time and wherewithal to do so, it is well worth the effort.
Yes, the harmonics of the fundamental bass frequency are what dominate the character of 'bass' tones. We have done experiments where we even changed the frequency of the fundamental while maintaining the harmonics and it is interesting how much it can be changed without hearing a change in pitch.
I would agree that LF control is another dimension of quality that is important, but we may differ as to whether that can be available from a high Q transducers. I have found that it can, but it is not easy to do so.
Thanks for your thoughts.
- Jim C.
Jim,
A little off topic, but when are you going to move back to the NW?
I was just thinking about that Fulton J Modular clone that Craig Heiser had. It still stirs the soul, what a great sounding speaker that was!
A month or so ago I was talking to an audio buddy, a fellow named Jerry Laster, and he asked if I knew what you've been doing. So are you still keeping busy?
Best Regards,
TerryO
A little off topic, but when are you going to move back to the NW?
I was just thinking about that Fulton J Modular clone that Craig Heiser had. It still stirs the soul, what a great sounding speaker that was!
A month or so ago I was talking to an audio buddy, a fellow named Jerry Laster, and he asked if I knew what you've been doing. So are you still keeping busy?
Best Regards,
TerryO
TerryO said:
Hi Terry!
Always great to hear from the old Seattle gang.
I was thinking of Mr. Heiser and wondering if he still had the InfraWoofer I gave him plans for. It was a 5 Hz Velocity Coupled Holliman resonator that made the beams in his house creek and squeal...lots of fun.
I've been working in San Diego for the last 10 years at American Technology on new types of ultrasonic to audio parametric loudspeakers (HyperSonic Sound - HSS™). Very high direcitivity (<5 degrees dispersion). Also, very high output long range directional acoustic hailing devices (LRAD). Additionally, new electrostatic and planar magnetic transducers, and new types of bandpass subwoofers, among other things. I left ATC a few months ago and am working on a number of new technologies and hope to move back to Seattle within a year or so. I still maintain owner ship in the Definitive Audio stores, but am less involved...mainly as a board member.
Yes, still keeping very busy.
Say hello to Jerry for me, and Craig too, if you see him.
I hope all is well with you guys...Maybe I"ll be seeing you soon.
Thanks for checking in...
All the best,
- Jim Croft
I just saw these on e***
Would these give enough bass to use just one??
Googled but could find no information, has any-one used these? or heard them or willing to offer an opinion?
http://cgi.ebay.com.au/ws/eBayISAPI...m=300242377505&ssPageName=STRK:MEWA:IT&ih=020
Assuming big is better I may be willing to take a chance on them it all depends on price Vs application I suppose
Would these give enough bass to use just one??
Googled but could find no information, has any-one used these? or heard them or willing to offer an opinion?
http://cgi.ebay.com.au/ws/eBayISAPI...m=300242377505&ssPageName=STRK:MEWA:IT&ih=020
Assuming big is better I may be willing to take a chance on them it all depends on price Vs application I suppose
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.