mige0 said:
And here I thought it was just the page..
Actually there are some problems with Alinco and suggesting a specific sound from the magnetic behaviour generally based on counter current flux modulation (..perhaps its somewhere in the thread, but after many pages I gave up).
Dan says something like "stay away from Alinco because it has soft compression like character due to an IN-ability to resist flux modulation.." Well.. that depends entirely on the field strength of the magnet (and any iron used to augment it - if any), its field "structure", the vc in relation to the field, and the amount of resulting counter current flux modulation (which is highly mms, excusion, current input dependent).
(..of course while stronger motors resist counter current flux modulation they also return stronger counter current flux modulation than weaker motors (all else equal). But it isn't equal. Again, you really need to look at mms and excursion to get a "feel" mechanically, then factor in how much current is being "pushed in" for how much counter current will be generated.)
A weak guitar speaker motor *MIGHT* display this behaviour. I would think that it almost certainly WOULD display this if the VC starts to leave the gap (..but then ANY moving coil will do that). Inside the gap its largely dependent on how long the gap is and how linear force is distributed by the motor.
However, most of these designs are very short gap "affairs" with low moving mass and low linear excursion. Keep the driver operating linearly, and it would likely NOT exhibit compression like behavior.
Ironically, consider what Dan sells to the public and industry alike..
HIGH MASS
HIGH EXCURSION
WEAK MOTORS along a LONG GAP
Now who's designs exhibit compression like effects at normal spl's?
The write-up on the Celestion Blue says it was derived from a radio speaker, ie an audio use. Might well explain its decent smooth and extended response. You are right, the Gold doesn't have the same charm- at least on paper.
Well, it looks like the Tone Tubby comes out of this recent discussion looking better than ever. After all this , I'm more curious and hopeful that the hemp drivers: TT and HA both are still prime candidates.
Lynn needs to order a pair of TT's ASAP!
Well, it looks like the Tone Tubby comes out of this recent discussion looking better than ever. After all this , I'm more curious and hopeful that the hemp drivers: TT and HA both are still prime candidates.
Lynn needs to order a pair of TT's ASAP!
Hello,
I've read about the new proposed drivers. I was wondering... can't some more specific design guidelines help more when choosing the driver?
For example, it seems that 1st order crossovers are out of discussion, but what do you think about higher cross points in order to preserve a coherence (in phase, in distorsion character) in the midrange?
I know that Mr. Lynn Olson uses a rather high cross point in his Ariel (especially being a d'Apolitto configuration) at 3.8Khz. There are some other advantages when crossing that high besides the coherence in the midrange... like low distorsion coloration for the tweeter. Would this be for example a design tag worth discussing?
I've read about the new proposed drivers. I was wondering... can't some more specific design guidelines help more when choosing the driver?
For example, it seems that 1st order crossovers are out of discussion, but what do you think about higher cross points in order to preserve a coherence (in phase, in distorsion character) in the midrange?
I know that Mr. Lynn Olson uses a rather high cross point in his Ariel (especially being a d'Apolitto configuration) at 3.8Khz. There are some other advantages when crossing that high besides the coherence in the midrange... like low distorsion coloration for the tweeter. Would this be for example a design tag worth discussing?
salas said:
Not when there's a crossover and enclosure added to the mix. When you measure a speaker with a high-resolution realtime system (MLS with rapid updates), you can see the rapid fluctuations in FR as the microphone is slowly swept from left to right, and up and down. Beyond a critical distance, these smooth out - if the speaker is competently designed, that is.
The entry into the smooth region is quite abrupt and obvious when measuring different speaker systems. In practical terms, it marks the transition from the near-field, with its chaotic changes in response with changes in microphone position of a few inches, to the far field, where the microphone has to be swept across quite a wide arc to see any significant changes. In addition, the fine-grained ripples start to smooth out as well.
Obviously, there's no point to optimizing a speaker for best response at 1 meter unless it is specifically designed for near-field use, and marketed as such. Speakers designed for domestic listening are optimized for performance at 2 meters and beyond. In a multiway speaker, you can't optimize for nearfield and far-field response - you have to choose one or the other. This is especially true for any speaker larger than a minimonitor.
The $tereophile method of measuring at 50 inches falls between the two stools, being neither useful for a true far-field measurement nor close enough for near-field monitoring applications. A speaker optimized for $tereophile's 50-inch distance will in fact be wrong for distances of 2 meters or more.
5 times a 15 inch is 191 cm Lynn. 5 times a 12 is 153 cm. We followed this rule of thumb for 15 inchers and 12 inchers in prof reinforcement when setting up processors by unit then taking samples 15, 25, 50, 100m from a 2 or 3 channel array field as a whole or even further if delay towers were involved. In home audio I go 1.6m and over all the time. But your project is gonna use biggies so I did not mean 5 times a 5 incher or something.
The proper technical thing is: ''The engineering definition of the "far-field" is |Rp|>2D2/λ, where D is the diameter of the smallest sphere that can enclose all of the sound sources. ''
Hey! I am not a $tereophile proponent! You had the 'Ariel' published in PF and I had 'The Slim', remember? I dont think they ever published something else for building a speaker. Or not?
The proper technical thing is: ''The engineering definition of the "far-field" is |Rp|>2D2/λ, where D is the diameter of the smallest sphere that can enclose all of the sound sources. ''
Hey! I am not a $tereophile proponent! You had the 'Ariel' published in PF and I had 'The Slim', remember? I dont think they ever published something else for building a speaker. Or not?
It was a conversation I tried to have with the S'phile staff many years ago at the CES and got absolutely nowhere. At the time, all of their speaker-measurement graphs were showing 15.75 kHz artifacts (in addition to the nonstandard measuring distance) I let them know they were getting broadcast TV signals in their microphone, which would corrupt the rest of the data with TVI.
I found that out the hard way by listening to my own microphone on occasion, and hearing the distinctive sync buzz noise of TV breakthrough. In the magazine, though, they "explained" the data by saying the computer monitor was interfering with the microphone. Wrong. I own MLSSA, and it doesn't run at the CGA display rate - it supports EGA and VGA only, which have quite a bit faster horizontal rates than NTSC television.
A few years later when I was on the editorial board of PF magazine, I was told the (unattributed) story that S'phile was actually proud of their lack of technical knowledge - that they felt it kept them "objective."
Frankly, I hoped it was nothing more than a rumor, since the magazine still has a make-or-break power for the US hifi industry. All it takes is one bad review, or possibly worse, one of those "damn-with-faint-praise" reviews, and bye-bye startup company. That's too much power in one set of hands.
I found that out the hard way by listening to my own microphone on occasion, and hearing the distinctive sync buzz noise of TV breakthrough. In the magazine, though, they "explained" the data by saying the computer monitor was interfering with the microphone. Wrong. I own MLSSA, and it doesn't run at the CGA display rate - it supports EGA and VGA only, which have quite a bit faster horizontal rates than NTSC television.
A few years later when I was on the editorial board of PF magazine, I was told the (unattributed) story that S'phile was actually proud of their lack of technical knowledge - that they felt it kept them "objective."
Frankly, I hoped it was nothing more than a rumor, since the magazine still has a make-or-break power for the US hifi industry. All it takes is one bad review, or possibly worse, one of those "damn-with-faint-praise" reviews, and bye-bye startup company. That's too much power in one set of hands.
The Story So Far
Well, this is an area where personal preference enters into the design. I aim for flat response and low coloration first, but dynamic range and low IM distortion follow closely behind. Other designer prioritize maximum SPL's, others go for perfect square waves, other adhere to THX criteria for home theater. All of these pull the speaker design in different directions.
The way things look now, I'm leaning towards:
HF: Radian 850-PB or 950-PB 2" compression driver + Azurahorn AH-550 Le Cleac'h-profile horn. (Alternates for the tweeter are the Mundorf Heil AMT tweeter, or possibly one of the big prosound ribbons.) The most likely crossover for the Radian + Azurahorn will be around 1.2 kHz at 12, 18, or 24 dB/oct, depending on what sounds best. The attenuator will be a custom 1-dB step autoformer or transformer from BudP or Dave Slagle.
Rear HF: One or two 18Sound XD125's horn/drivers facing backward and mounted directly below the MF driver, on the rear surface of the open baffle. They will have crossovers at 2.5 kHz or higher, and will have attenuation in 1 dB steps. Working together with the front HF driver, the rear HF drivers generate a hypercardioid pattern instead of the usual 90-degree dispersion of horn systems. One of the most important criteria for selection for the rear HF drivers are smooth responses free of narrowband resonances.
Widerange MF: 12" 18Sound 12NDA520 or 12" Alnico Tone Tubby, with a lowpass filter around 1.2 kHz. The to-be-determined topology of this filter would be developed first, and aim at the smoothest possible rolloff - this to be determined by measurement and audition on full-range source material. I don't think I'll be using a highpass filter on the MF driver, although this can be determined by audition. The MF driver is mounted at the top of an asymmetric open baffle, with the L/R distances to the edge of the mounting surface a Golden Section ratio of 1:1.618.
Midbass: Either a 15" Tone Tubby, a 15" 18Sound, or a pair of 12" drivers operating in push-pull. The push-pull variant would have the drivers in 16-ohm versions connected in parallel, and mounted side-by-side with one driver reversed (magnet facing out). The midbass drivers, of whatever type, will be mounted at floor level in a short box with an open rear and filled with recycled-cotton damping material.
The midbass drivers will have 1st-order lowpass filters tuned to offset the 1/f loss of the MF driver, which will start dropping off around 200 Hz or slightly lower. The midbass drivers will also have additional steeper-slope filters set to about 1 kHz or so, to prevent interference with the HF driver.
The expected response of the speaker system should be from about 70~80 Hz to 20 kHz, and efficiency in the 97 to 100 dB/metre range. The design target is flatness comparable to the Ariel, as good or better energy storage, 10~15 dB more dynamic range, and a dipole/hypercardioid radiation pattern over most of the frequency range of the system. It would nice if it sounded good.
SunRa said:
Well, this is an area where personal preference enters into the design. I aim for flat response and low coloration first, but dynamic range and low IM distortion follow closely behind. Other designer prioritize maximum SPL's, others go for perfect square waves, other adhere to THX criteria for home theater. All of these pull the speaker design in different directions.
The way things look now, I'm leaning towards:
HF: Radian 850-PB or 950-PB 2" compression driver + Azurahorn AH-550 Le Cleac'h-profile horn. (Alternates for the tweeter are the Mundorf Heil AMT tweeter, or possibly one of the big prosound ribbons.) The most likely crossover for the Radian + Azurahorn will be around 1.2 kHz at 12, 18, or 24 dB/oct, depending on what sounds best. The attenuator will be a custom 1-dB step autoformer or transformer from BudP or Dave Slagle.
Rear HF: One or two 18Sound XD125's horn/drivers facing backward and mounted directly below the MF driver, on the rear surface of the open baffle. They will have crossovers at 2.5 kHz or higher, and will have attenuation in 1 dB steps. Working together with the front HF driver, the rear HF drivers generate a hypercardioid pattern instead of the usual 90-degree dispersion of horn systems. One of the most important criteria for selection for the rear HF drivers are smooth responses free of narrowband resonances.
Widerange MF: 12" 18Sound 12NDA520 or 12" Alnico Tone Tubby, with a lowpass filter around 1.2 kHz. The to-be-determined topology of this filter would be developed first, and aim at the smoothest possible rolloff - this to be determined by measurement and audition on full-range source material. I don't think I'll be using a highpass filter on the MF driver, although this can be determined by audition. The MF driver is mounted at the top of an asymmetric open baffle, with the L/R distances to the edge of the mounting surface a Golden Section ratio of 1:1.618.
Midbass: Either a 15" Tone Tubby, a 15" 18Sound, or a pair of 12" drivers operating in push-pull. The push-pull variant would have the drivers in 16-ohm versions connected in parallel, and mounted side-by-side with one driver reversed (magnet facing out). The midbass drivers, of whatever type, will be mounted at floor level in a short box with an open rear and filled with recycled-cotton damping material.
The midbass drivers will have 1st-order lowpass filters tuned to offset the 1/f loss of the MF driver, which will start dropping off around 200 Hz or slightly lower. The midbass drivers will also have additional steeper-slope filters set to about 1 kHz or so, to prevent interference with the HF driver.
The expected response of the speaker system should be from about 70~80 Hz to 20 kHz, and efficiency in the 97 to 100 dB/metre range. The design target is flatness comparable to the Ariel, as good or better energy storage, 10~15 dB more dynamic range, and a dipole/hypercardioid radiation pattern over most of the frequency range of the system. It would nice if it sounded good.
Hmm..perhaps something of an esthetic cross between a Linkwitz Orion and this:
http://www.sonicflare.com/archives/vegas07-vision-of-the-future-emerald-audio.php
..obviously more in-keeping with the Orion's size.
I think a stable "resistive" impedance will need to be considered to keep with the "flat response" objective and still be used with amplifiers that react with impedance.
http://www.sonicflare.com/archives/vegas07-vision-of-the-future-emerald-audio.php
..obviously more in-keeping with the Orion's size.
I think a stable "resistive" impedance will need to be considered to keep with the "flat response" objective and still be used with amplifiers that react with impedance.
reliability
Hi
ScottG I am not so much concerned about the "ALNICO sound" as it may balance nice with the otherwise low coloration concept (open baffle, hemp cone). No one knows until no one has tried! I had some nice experiences with this "ALNICO sound" from vintage gear as well.
What would keep me off from ALNICOs is reliability.
http://www.diyaudio.com/forums/showthread.php?postid=605538#post605538
"http://www.diyaudio.com/forums/showthread.php?postid=605538#post605538"
This might not be an issue as long as you are with guitar combos but with an all passive design someone fires up with a high output amplifier it most likely is.
Great link to the Emerald's Nemesis!
Greetings Michael
Hi
ScottG I am not so much concerned about the "ALNICO sound" as it may balance nice with the otherwise low coloration concept (open baffle, hemp cone). No one knows until no one has tried! I had some nice experiences with this "ALNICO sound" from vintage gear as well.
What would keep me off from ALNICOs is reliability.
http://www.diyaudio.com/forums/showthread.php?postid=605538#post605538
"http://www.diyaudio.com/forums/showthread.php?postid=605538#post605538"
This might not be an issue as long as you are with guitar combos but with an all passive design someone fires up with a high output amplifier it most likely is.
Great link to the Emerald's Nemesis!
Greetings Michael
How about the Ciare 12.00W1 for the mids? Qts is low, but how low will it need to play? It looks relatively smooth to me:
http://www.ciare.com/oem_new/pdf/12.00W1.pdf
http://www.ciare.com/oem_new/pdf/12.00W1.pdf
Lynn Olson said:
???
That must have been a long time ago, if they ran monitors at 15.75 Khz. Or were they watching TV while they did the measurements?
FWIW, the scan rate of modern computer monitors is far beyond the audible range, up at 60Khz and above.
I used to be annoyed by the 15.75Khz whine of TVs. Not any more - that's an advantage of age.
panomaniac said:
That must have been a long time ago, if they ran monitors at 15.75 Khz. Or were they watching TV while they did the measurements?
FWIW, the scan rate of modern computer monitors is far beyond the audible range, up at 60Khz and above.
I used to be annoyed by the 15.75Khz whine of TVs. Not any more - that's an advantage of age.
Early MLSSA system, running DOS 3.2 through 6.0, on 286 and 386 PC's with the abomination of "expanded" memory (the ol' 640K brick wall of antique PC's). The earliest graphics were "Hercules" monochrome graphics and CGA color at 320 x 240. Very fuzzy, huge pixels, only four colors, the only merit CGA had was that it ran at the TV sync rate.
MLSSA was second-generation DOS/PC, thus supported better graphics (in fact, required them) and expanded memory models. My card is so old that it will NOT run on any ISA bus faster than 8 MHz - Gary Pimm and I tried, and we know that it WON'T work with a 8.25 MHz bus.
The current-generation MLSSA cards do run faster than 8 MHz, but still unfortunately require not only DOS, but an ISA bus - and how many years has it been since ISA was offered on any motherboard - hmm, maybe 250~333 MHz Pentium II vintage?
As for TV breakthrough, phantom-powered condenser instrumentation microphones are prone to RF interference. When I lived in Portland, we were about 15 miles from the transmitter towers, but I still had problems with television RFI intruding on the microphone. I know what TV sync buzz sounds like - a whirr that changes somewhat depending on picture content - and that's what I heard. If it's computer-monitor breakthrough, you're not going to hear the fluctuations that TV pictures have, with their constant scene changes and associated changes in the TV waveform (bright to dark transitions, for example).
What's really weird - and I have no explanation whatever for this - I can easily hear the horizontal sync whistle of 1080i HDTV! I shouldn't be able to hear this at all, it's around 35 kHz or so (the horizontal rate is a bit faster than 480P).
PaulW has posted a set of measurements of the 18Sound 12NDA520 driver in a small open baffle. Not perfectly flat, but usable, especially with a crossover at 1.2 kHz. Does make me wonder about a notch filter at 2 kHz, though, considering the CSD plot.
The real shocker is the SEAS W26 driver in the top two sets of measurements - high-Q resonances combined with low efficiency. Just to make things interesting, I'll bet the resonances are directional as well, which makes equalization pretty challenging.
For those considering a true 3-way instead of the 2.5 or 2.5.5 system I've been describing, the 18Sound 8NMB420 looks like a real charmer, with superb measurements. This driver could be used with a much higher crossover of at least 2.5 kHz, which in turn would open the door to a wide range of high-efficiency ribbon tweeters.
It's also a bit less efficient at 95.5 dB/metre, which also allows for a wider choice of tweeters. The only downside I see is that 8NMB420 is more of a midrange driver, although the linear Xmax of +/- 5.75 mm is nothing to sneeze at - that's quite good, and a lot better than the guitar speakers we've been discussing. Even so, if I were using this driver (and I might), I'd high-pass it around 160 to 250 Hz, just to keep the low-bass out and keep the driver in the linear region. I'd let the 12 or 15-inch driver below do the heavy lifting in the 200 Hz-and-lower region.
You can see I've playing with the avatar feature of the forum - the mysterious pix is looking up at the V2 rocket in the Deutsches Museum in Munich. The other avatar I'm considering is a slightly comical picture of me in India in 1991, sitting under a tree and looking the part of a guru.
The real shocker is the SEAS W26 driver in the top two sets of measurements - high-Q resonances combined with low efficiency. Just to make things interesting, I'll bet the resonances are directional as well, which makes equalization pretty challenging.
For those considering a true 3-way instead of the 2.5 or 2.5.5 system I've been describing, the 18Sound 8NMB420 looks like a real charmer, with superb measurements. This driver could be used with a much higher crossover of at least 2.5 kHz, which in turn would open the door to a wide range of high-efficiency ribbon tweeters.
It's also a bit less efficient at 95.5 dB/metre, which also allows for a wider choice of tweeters. The only downside I see is that 8NMB420 is more of a midrange driver, although the linear Xmax of +/- 5.75 mm is nothing to sneeze at - that's quite good, and a lot better than the guitar speakers we've been discussing. Even so, if I were using this driver (and I might), I'd high-pass it around 160 to 250 Hz, just to keep the low-bass out and keep the driver in the linear region. I'd let the 12 or 15-inch driver below do the heavy lifting in the 200 Hz-and-lower region.
You can see I've playing with the avatar feature of the forum - the mysterious pix is looking up at the V2 rocket in the Deutsches Museum in Munich. The other avatar I'm considering is a slightly comical picture of me in India in 1991, sitting under a tree and looking the part of a guru.
Attachments
Thanks for the info, Lynn. That's old stuff indeed. I did projected subtitles off an Apple IIe back in the mid 80s. Wonder what scan rate that was? Not high, for sure.
Well... My home computer is a 450Mhz PII with an ISA slot. This message comes to you via that ISA slot and the ethernet card in it. A great old 1998 Micron that just won't quit. Also have 4 DOS machines at work that run ISA slots to drive Iris printers. So ISA lives!
I like the guru pic. Thought you were in Hawaii. The Dalai Lama was just here on Maui. He liked the Hawaiian leis, said the leis in India often had worms.
Lynn Olson said:
Well... My home computer is a 450Mhz PII with an ISA slot. This message comes to you via that ISA slot and the ethernet card in it. A great old 1998 Micron that just won't quit. Also have 4 DOS machines at work that run ISA slots to drive Iris printers. So ISA lives!
I like the guru pic. Thought you were in Hawaii. The Dalai Lama was just here on Maui. He liked the Hawaiian leis, said the leis in India often had worms.
PaulW measurements are very helpful. Seems the published 18Sound curves have no smoothing, which is a good thing to pre-select drivers reading at them.
The 8" driver Lynn mentioned is really nice: if it gets the same lift on the lower end from the baffle Pawl W used one might be able to come with no crossover (but the LP filter at 150-200). It has a 10 Tm BL and 14.9gm mms. The 6" I mentioned before (6ND410) has a higher BL (11.6) and a much lower moving mass (8.2 gms), but the radiating surface is a bit more than half of that from the 8 inch driver, and Xmax is less than half (2mm p-p). A good thing is that both drivers have a moderate price, while the 10" Paul measured costs twice more.
Considering the gain from a similar baffle as PaulW´s, the 6"er should be roughly flat to 500 Hz (due to its rising response) while the bigger 8"would be flat down to 300Hz.
Wouldn`t the 8" incher still have a small rise above 1Khz up to the crossover point?
Lynn, how important for you is the BL/ MMS ratio?
The 8" driver Lynn mentioned is really nice: if it gets the same lift on the lower end from the baffle Pawl W used one might be able to come with no crossover (but the LP filter at 150-200). It has a 10 Tm BL and 14.9gm mms. The 6" I mentioned before (6ND410) has a higher BL (11.6) and a much lower moving mass (8.2 gms), but the radiating surface is a bit more than half of that from the 8 inch driver, and Xmax is less than half (2mm p-p). A good thing is that both drivers have a moderate price, while the 10" Paul measured costs twice more.
Considering the gain from a similar baffle as PaulW´s, the 6"er should be roughly flat to 500 Hz (due to its rising response) while the bigger 8"would be flat down to 300Hz.
Wouldn`t the 8" incher still have a small rise above 1Khz up to the crossover point?
Lynn, how important for you is the BL/ MMS ratio?