Hi There,
I was looking to buy a Audio Nirvana 15" Co-ax that come with a compression drive or to use a normal Audio Nirvana 15" with an external ribbon tweeter.
Ideally the compression driver would be a better match than the ribbon tweeter, since it is built into the speaker driver. However I am clueless about how the sound characteristics of a compression driver?
How is the sound like, harsh, detailed, airy, smooth?
If you have made a comparison of compression driver with other types of drivers domes, metal or ribbons, I would very much like to hear what you say on them.
Many thanks ahead.
Oon
I was looking to buy a Audio Nirvana 15" Co-ax that come with a compression drive or to use a normal Audio Nirvana 15" with an external ribbon tweeter.
Ideally the compression driver would be a better match than the ribbon tweeter, since it is built into the speaker driver. However I am clueless about how the sound characteristics of a compression driver?
How is the sound like, harsh, detailed, airy, smooth?
If you have made a comparison of compression driver with other types of drivers domes, metal or ribbons, I would very much like to hear what you say on them.
Many thanks ahead.
Oon
Balancing Act
What sounds the best to your ears will be determined primarily by your listening room, enclosure placement, the quality of the driver units used, and not particularly the choice of one set of system design trade-offs over another set.
A compression driver, by design, improves electrical to acoustical conversion efficiency and requires use of a horn to transform the acoustical high impedance of the diaphragm to a low one of the surrounding air. This type of baffle focuses sound into a narrowed dispersion pattern that reduces the relative intensity of early reflections from adjoining room walls. When used as the center element of a coaxial driver, the assemblage avoids source bifurcation and behaves as an ideal point source in the near as well as far field.
Use of a separate ribbon tweeter and cone woofer drivers, trades these characteristics for a low mass tweeter diaphragm, sans voice coil, totally immersed in a magnetic field. Here in the near field it behaves as a line source; however, at the low crossover frequency that is most likely, the dispersion patterns of both drivers will remain sufficiently matched.
Regards,
WHG
What sounds the best to your ears will be determined primarily by your listening room, enclosure placement, the quality of the driver units used, and not particularly the choice of one set of system design trade-offs over another set.
A compression driver, by design, improves electrical to acoustical conversion efficiency and requires use of a horn to transform the acoustical high impedance of the diaphragm to a low one of the surrounding air. This type of baffle focuses sound into a narrowed dispersion pattern that reduces the relative intensity of early reflections from adjoining room walls. When used as the center element of a coaxial driver, the assemblage avoids source bifurcation and behaves as an ideal point source in the near as well as far field.
Use of a separate ribbon tweeter and cone woofer drivers, trades these characteristics for a low mass tweeter diaphragm, sans voice coil, totally immersed in a magnetic field. Here in the near field it behaves as a line source; however, at the low crossover frequency that is most likely, the dispersion patterns of both drivers will remain sufficiently matched.
Regards,
WHG
any chance we could put in a almost ?
apart from that, a woofer cone is not the ideal waveguide for a compression driver
is it enough advantage to be a good point source ? maybe it is in some cases
but usually the driver/waveguide match appears to be the key to a good result
even the best driver in the world wont help you one bit if not set up properly
I would also consider to use a dedicated tweeter amp
which again could cause some other 'issues'
Sure!
The absence of perfection, in all models, is always presumed, particularly at envelope extremes. That notion includes as well, my brief comment made here about coaxial driver configurations. I suppose the substitution of the word "like" for the word "as" in the sentence in question would also provide the necessary caveat for those of pedantic persuasion.
Regards,
WHG
any chance we could put in a almost ?
The absence of perfection, in all models, is always presumed, particularly at envelope extremes. That notion includes as well, my brief comment made here about coaxial driver configurations. I suppose the substitution of the word "like" for the word "as" in the sentence in question would also provide the necessary caveat for those of pedantic persuasion.
Regards,
WHG
What makes "the sound" from a compression driver?
It's a
Large Dome tweeter with massive magnet
+
Compression Chamber leading into a Phase Plug
+
throat
+
waveguide profile
+
waveguide termination
In short, if you look at the coax itself:
Its surround and cone profiles, and the baffle it will be mounted in, will all affect the sound in terms of on AND off-axis frequency response.
Then you have to consider the transition from the throat to the coaxial. Since the cone moves, there is a sure discontinuity. Whether it matters is debatable. The size of the throat determines the ability to produce high frequency response
Finally you're down to the dome itself. It will have its own resonances, for example diaphragm breakup. A 1.8" dome probably breaks up lower than a 0.75" dome, and has its displacement limitations too. It has to be stiff to deal with the high level of compression it is under. It has to have good control over magnetic flux to ensure a very consistent sound.
Last but not least you have the crossover. it affects what you're asking of the compression driver, what you're asking of the cone it's mated to, etc.
So the answer is... just like any other driver type it totally is case-specific. There is no one compression driver `"sound" just like there's no one ribbon sound or one flushmount dome sound. Like with any of those, it's possible that colorations can be introduced through poor driver design or poor system design. But it's also possible for a CD to be very transparent - but often gets expensive with respect to exotic diaphragm materials. Generally you can squeeze about a decade of bandwidth out of a compression driver with a very consistent dispersion pattern - which often makes them a good choice for upper mids and the treble. They may not have the exact reach of a ribbon in the top octave as a result though. Still, ~15khz extension out of a 1-inch CD is perfectly adequate for most people. If you do have a lot of hearing above 14khz, then perhaps a cheap ribbon supertweeter with a steep crossover slope could be an option - IE Hi-Vi RT1.3C - assuming you can match sensitivity or use an active crossover. A compression driver could be made with higher frequency reach, but then it wouldn't extend as a low. It's a pick-your-bandwidth poison. Arguably two-ways are just inherently too zealous.
A 12" Coaxial like the BMS 12C362 can still have a very wideband response. I don't know what to say about the Audio Nirvana unit. Not much information is given.
It's a
Large Dome tweeter with massive magnet
+
Compression Chamber leading into a Phase Plug
+
throat
+
waveguide profile
+
waveguide termination
In short, if you look at the coax itself:
An externally hosted image should be here but it was not working when we last tested it.
Its surround and cone profiles, and the baffle it will be mounted in, will all affect the sound in terms of on AND off-axis frequency response.
Then you have to consider the transition from the throat to the coaxial. Since the cone moves, there is a sure discontinuity. Whether it matters is debatable. The size of the throat determines the ability to produce high frequency response
Finally you're down to the dome itself. It will have its own resonances, for example diaphragm breakup. A 1.8" dome probably breaks up lower than a 0.75" dome, and has its displacement limitations too. It has to be stiff to deal with the high level of compression it is under. It has to have good control over magnetic flux to ensure a very consistent sound.
Last but not least you have the crossover. it affects what you're asking of the compression driver, what you're asking of the cone it's mated to, etc.
So the answer is... just like any other driver type it totally is case-specific. There is no one compression driver `"sound" just like there's no one ribbon sound or one flushmount dome sound. Like with any of those, it's possible that colorations can be introduced through poor driver design or poor system design. But it's also possible for a CD to be very transparent - but often gets expensive with respect to exotic diaphragm materials. Generally you can squeeze about a decade of bandwidth out of a compression driver with a very consistent dispersion pattern - which often makes them a good choice for upper mids and the treble. They may not have the exact reach of a ribbon in the top octave as a result though. Still, ~15khz extension out of a 1-inch CD is perfectly adequate for most people. If you do have a lot of hearing above 14khz, then perhaps a cheap ribbon supertweeter with a steep crossover slope could be an option - IE Hi-Vi RT1.3C - assuming you can match sensitivity or use an active crossover. A compression driver could be made with higher frequency reach, but then it wouldn't extend as a low. It's a pick-your-bandwidth poison. Arguably two-ways are just inherently too zealous.
A 12" Coaxial like the BMS 12C362 can still have a very wideband response. I don't know what to say about the Audio Nirvana unit. Not much information is given.
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From another perspective, here are a couple of reviews regarding the sound of compression drivers vs ribbons and AMTs. It might give you some ideas of the virtues of each:
B&C HF drivers DE400TN & DE35 - [English]
[Review] ESS Heil Air Motion Transformer - [English]
B&C HF drivers DE400TN & DE35 - [English]
[Review] ESS Heil Air Motion Transformer - [English]
Oon,
On a good horn, even at a very loud level, a properly equalized compression driver sounds very much like the source material.
I did a series of tests which allows you to hear the sound of a variety of compression drivers at various levels.
The “Full Monty” has been posted Here:
http://www.diyaudio.com/forums/multi-way/212240-high-frequency-compression-driver-evaluation.html
A shorter version (only 3000 rather than 8000 words, and a lot less pictures) can be found here:
High Frequency Compression Driver Evaluation
The sound files in the soundforums.net posts do not have the low frequency portion of the music mixed in, listening to the HF horn alone makes it easier to hear the difference in sound quality and distortion between the drivers.
The recordings afford an insight in compression driver comparison (as far as I know) never undertaken before this study.
Hope you will enjoy the opportunity to compare the different driver’s sound without all the usual problems associated with A/B/C/D/E/F testing.
Art Welter
Thank you for all the lengthy replies. Will take me a bit of time to digest everything. Could i summarise everything into a few sentence
1. Sound quality could have quite a bit of variaance. Depending on well the horn was designed.
2. A 2 inch compression driver is unlikely to work well in the very high frequency region ..as a supertweeter of sorts. Really needs a much smaller one.
3. The sound will be highly directional rather than dispersed.
4. Unlikely the compression driver in a coax will sound good because of the lack of control over the size and shape of the horn.
Would that be correct?
Oon
1. Sound quality could have quite a bit of variaance. Depending on well the horn was designed.
2. A 2 inch compression driver is unlikely to work well in the very high frequency region ..as a supertweeter of sorts. Really needs a much smaller one.
3. The sound will be highly directional rather than dispersed.
4. Unlikely the compression driver in a coax will sound good because of the lack of control over the size and shape of the horn.
Would that be correct?
Oon
3. A more normal tweeter such as dome or ribbon in the high octave. From what i read, that is suppose to be the advantage, no reflections from sidewalls.
4. Compared to a normal compression driver with a proper horn. The coax will depend on the whizzer cone as the horn so it will be limited in its optimisation. Correct/incorrect?
As well as the crossover.
A 15" mid does not want a supertweeter, it wants a mid tweeter. Regardless of hype from the full range crowd, taking it far above 1khz is a hit to fidelity. A supertweeter would compliment a 2" exit CD better than it would compliment a 15" full range.
Normally coaxial cones act as 120 to 80 degree conical horns with a constant beamwidth. It's directional, yes.
A large format conical horn ain't bad at all. There are some tradeoffs but a good concentric coaxial can sound phenominal. The Soundfield Audio 1812 Overture comes to mind.
Nota Bene
The Audio Nirvana 'Super 15 Coax is a Tri-Axial, Hybrid Full-Range Driver
Low Frequencies:
are reproduced by a Large Cone decoupled from the Voice Coil at Mid Frequencies by a Compliance (mechanical crossover).
Mid & Low Frequencies as well:
are reproduced by a Whizzer Cone, directly attached to the Voice Coil.
Mass of the Large Whizzer and Voice Coil, rolls-off the highs.
High Frequencies:
are reproduced by a Separate, Coaxially Mounted Super Tweeter, that is protected by a Series Capacitor.
From CommonSense Audio the following description is provided:
Audio Nirvana Full-Range Speakers For Sale. High Efficiency, DIY, Single Driver, Monitor Speakers with no crossover.
“The Audio Nirvana 'Super 15 Coax' ($698/pr) has a frequency response from 26 Hz to 25,000 Hz. You can expect at least 99 db efficiency when installed in any of our cabinets. It handles 70 watts continuous RMS (normal listening level will be about 1/10 watt). Impedance is 8 ohms. Voice coil is 2.0 inches (50 mm) for the woofer and 1.5 inches (38 mm) for the tweeter. Magnet weight is 4.3 lbs (woofer) and 4 oz (tweeter). Total weight is 19 lbs. The woofer cone is made of paper. The surround is accordion style and made of treated cloth. The frame is cast aluminum. There are separate terminals for the woofer and the tweeter so the speakers can be biwired, if desired. This speaker is more properly called a 'triaxial' because it has a whizzer cone for midrange information. The best classic coaxial drivers were also triaxials.”
Regards,
WHG
The Audio Nirvana 'Super 15 Coax is a Tri-Axial, Hybrid Full-Range Driver
Low Frequencies:
are reproduced by a Large Cone decoupled from the Voice Coil at Mid Frequencies by a Compliance (mechanical crossover).
Mid & Low Frequencies as well:
are reproduced by a Whizzer Cone, directly attached to the Voice Coil.
Mass of the Large Whizzer and Voice Coil, rolls-off the highs.
High Frequencies:
are reproduced by a Separate, Coaxially Mounted Super Tweeter, that is protected by a Series Capacitor.
From CommonSense Audio the following description is provided:
Audio Nirvana Full-Range Speakers For Sale. High Efficiency, DIY, Single Driver, Monitor Speakers with no crossover.
“The Audio Nirvana 'Super 15 Coax' ($698/pr) has a frequency response from 26 Hz to 25,000 Hz. You can expect at least 99 db efficiency when installed in any of our cabinets. It handles 70 watts continuous RMS (normal listening level will be about 1/10 watt). Impedance is 8 ohms. Voice coil is 2.0 inches (50 mm) for the woofer and 1.5 inches (38 mm) for the tweeter. Magnet weight is 4.3 lbs (woofer) and 4 oz (tweeter). Total weight is 19 lbs. The woofer cone is made of paper. The surround is accordion style and made of treated cloth. The frame is cast aluminum. There are separate terminals for the woofer and the tweeter so the speakers can be biwired, if desired. This speaker is more properly called a 'triaxial' because it has a whizzer cone for midrange information. The best classic coaxial drivers were also triaxials.”
Regards,
WHG
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Grist...
... for the Audio Nivana mill.
1) This project, with frequency plot, uses the 15” Driver sans Separate Tweeter.
review33.com - ????
2) 15" Coax Coax Driver spec. sheet with frequency plots
... for the Audio Nivana mill.
1) This project, with frequency plot, uses the 15” Driver sans Separate Tweeter.
review33.com - ????
2) 15" Coax Coax Driver spec. sheet with frequency plots
Attachments
As a kit builder DIYer for a few short years I have to say I have yet to use a full range wizer or coaxial because the published FRs are always so ragged from 2k to 6k and they fall off a cliff generally at 14k.
I can understand the point source addiction though as I've only recently come to understand/appreciate this after hearing some Danley labs. Combing and phase issues in multiways is more pronounced than most of us realize.
I find it interesting that so many old timer experts and gurus go to full range driver/coaxials in horns with BVR cabs etc.
There has gotta be something to it if these purists are into it!
Watching Don Keele's CBT address at Boston IEEE and his acoustic models it really hit home how detrimental these affects can be to a loudspeaker system.
Synergy horn is an interesting solution but I really like what CBT does in this regard scientifically.
I can understand the point source addiction though as I've only recently come to understand/appreciate this after hearing some Danley labs. Combing and phase issues in multiways is more pronounced than most of us realize.
I find it interesting that so many old timer experts and gurus go to full range driver/coaxials in horns with BVR cabs etc.
There has gotta be something to it if these purists are into it!
Watching Don Keele's CBT address at Boston IEEE and his acoustic models it really hit home how detrimental these affects can be to a loudspeaker system.
Synergy horn is an interesting solution but I really like what CBT does in this regard scientifically.
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