gedlee said:
The problem with that though is that readers may focus more on it than anything substantive. (..kind'a like an advertiser that hires a pretty lady to "palm" their product for a tv commercial - viewers may only remember the lady (and what she did or did not wear), and not the product or even the product name.)
ScottG said:
The problem with that though is that readers may focus more on it than anything substantive. (..kind'a like an advertiser that hires a pretty lady to "palm" their product for a tv commercial - viewers may only remember the lady (and what she did or did not wear), and not the product or even the product name.)
That sword cuts both ways. People love a "pretty lady" and the ladies presence will attract people to the product that may not come by another way. There's always a risk that they won't notice your product, but the high usage of "pretty ladies" in advertising implies otherwise.
And people love a good controversy. Open a paper with a boring recital of how your paper is not going to be controversial and they may not get to the second paragraph.
The statements in the first paragraph were not random, but well thought out to intice the reader into the rest of the work.
As I thought this through, I think that the opening is just what I wanted it to be. Frank, mildly sarcastic and promising of a very controversial finish.
As I said, I attempted to be polite, and not too personal or acusatory, but I don't see why a little sarcasm is a bad thing.
gedlee said:
In general I don't have problem with sarcasm either, or even the occasional good-natured "ripping".
..and advertising is a "balancing act" - but is the "act" itself even necessary in this instance, and if it is, have you achieved the proper "balance"? I don't know about the former, but if others question the latter (without focusing on substance) - then perhaps the "balance" has been shifted just a little to far.
But hey, it may very well be received in exactly the manner you want (..or perhaps even better than you intended).
gedlee said:
When some argument is backed up by data and makes solid logical (mathematical) sense, it is at least lousy not to appreciate it. There is certainly something musically bad going on with standard horns and compression drivers when we judge them for fidelity, putting aside their practical benefits in sound reinforcement for a while. Its time someone has to update them. I just wish you are wrong somewhere too, so there is some space for even some more improvements in the future.
I would like to see a gedlee 'Beyond the Summa' article here in 2012.P.S. What 'Summa' symbolizes by the way? Summation of knowledge?
salas said:
When some argument is backed up by data and makes solid logical (mathematical) sense, it is at least lousy not to appreciate it. There is certainly something musically bad going on with standard horns and compression drivers when we judge them for fidelity, putting aside their practical benefits in sound reinforcement for a while. Its time someone has to update them. I just wish you are wrong somewhere too, so there is some space for even some more improvements in the future.
P.S. What 'Summa' symbolizes by the way? Summation of knowledge?
It comes from the Latin "Summa-Cum-Laude" - "with highest honors", it means the very best.
There is a lot of room for improvement in the compression drivers now that we understand how the waveguide works. Waveguide theory has strong implications for compression driver design. But I don't make the compression drivers and I can't force the manufacturers to redesign them. Only as a group - customers - asking for these changes can we get the manufacturers to listen. There is no incentive to change something that people buy just the way it is.
Which would mean to have the pro-sound people make aware of this and then in turn the manufacturers.... so, probably the wrong forum here, I guess. But, OTOH there are many dogmatic traditionalists on the PA/pro-sound boards as well (I read a few) and something really radically new ususally gets heavily flamed, interrestingly even more so the more solid math is backing the claims (man vs. math --> man looses fight --> man gets grumpy --> ad hominem stuff --> bang!)gedlee said:
- Klaus
KSTR said:
All quite true and why I don't go to Pro sites. I don't mind talking to people and eduacting them, but I'm not about to argue about it on a web site. People will catch on, its inevitable. I just hope I live long enough to witness it. Live or dead, I will hold patents on the most important stuff. Unless it takes more than 17 years! Which is sometimes the case. I did my first waveguide paper about 20 years ago.
Re: Re: Re: high excursion musical instrument driver
Hello Gedlee:
Can I take it that since you did not reply to my post that my question is too far out there? I sometimes dream up these ideas and this one I figured I would post. I'm referring to the 12 inch compression driver.
Killjoy said:
Hello Gedlee:
Can I take it that since you did not reply to my post that my question is too far out there? I sometimes dream up these ideas and this one I figured I would post. I'm referring to the 12 inch compression driver.
Re: Re: Re: Re: high excursion musical instrument driver
I did respond back in 3249. Maybe not the complete answer that you may have wanted, but an answer none the less.
The larger the driver the more limited the HF response. I do my designs from the HF down, not the LF up. Probably not typical I know. I find the driver and waveguide configuration that gets me to the top end that I am looking for. Then I see how low this can go in frequency considering power, excursion, but mostly directivity. Then I match this up to the Mid-woofer that has the same directivity, etc. For this mid-woofer device to be a waveguide it would be enormous. The Summa 15 is already too big so going bigger is not an option. So I just don't see where a large diaphragm compression driver fits into my scheme. There are some 8" compression drivers used in very high output Pro, but thats a different world ruled by different requirements and sound quality is not high up on the list.
Killjoy said:
I did respond back in 3249. Maybe not the complete answer that you may have wanted, but an answer none the less.
The larger the driver the more limited the HF response. I do my designs from the HF down, not the LF up. Probably not typical I know. I find the driver and waveguide configuration that gets me to the top end that I am looking for. Then I see how low this can go in frequency considering power, excursion, but mostly directivity. Then I match this up to the Mid-woofer that has the same directivity, etc. For this mid-woofer device to be a waveguide it would be enormous. The Summa 15 is already too big so going bigger is not an option. So I just don't see where a large diaphragm compression driver fits into my scheme. There are some 8" compression drivers used in very high output Pro, but thats a different world ruled by different requirements and sound quality is not high up on the list.
I've been in communication with Martin Seddon, and can confirm that the rumor Azurahorns are going out of production is NOT true. He is continuing current production of the Azurahorn series. However, one setback has been Australian post no longer ships the AH-340 and the larger horns, requiring FedEx or UPS instead.
When I called FedEx and UPS, the price for shipping a pair of boxed AH-340's from Perth, Australia to Denver, USA was $550USD (FedEx) and $450USD (UPS). Australia post still can ship a pair of AH-550's from there to here at the much more moderate price of about $100USD.
Music Concrete in France has horns with similar profiles, made of concrete composite of course, at about twice the price (shipping included) as the Azurahorns. (The depressed USD/Euro ratio doesn't help here.) The quotes I've gotten from US-made wood horns are well above the Music Concrete price. A big attraction of the Azurahorn is the price is low enough to fall into what I consider the "experimental" range to play with different sizes and compression drivers. Not interested in small-format compression drivers, and don't need their HF extension since I already own supertweeters with complementary high efficiency, very low energy storage, and extension to 100 kHz.
Aside from shipping costs, I'm still going back and forth on the AH-340 vs the AH-550. The AH-340 (24" horn mouth diameter) is almost exactly twice as big as the AH-550 (12" diameter). The book by Newell and Dr. Holland recommends low-diffraction (no kinks in the acoustic path) horns with less than 12" of total length from diaphragm to horn-mouth. The authors point out that horns of this size and profile almost exactly mimic the 12" and 15" Tannoy Dual Concentrics, minus the weird modulation effects of the moving bass diaphragm.
This recommendation points towards the seven-inch-long AH-550, while the AH-340 offers the attractive option of a lower crossover and possibly lower distortion in the 1 kHz region. Essentially, a tradeoff between a 1:2 difference in energy storage (smaller horn, shorter delays, Tannoy dimensions) vs somewhat higher IM distortion from decreased diaphragm loading.
When I called FedEx and UPS, the price for shipping a pair of boxed AH-340's from Perth, Australia to Denver, USA was $550USD (FedEx) and $450USD (UPS). Australia post still can ship a pair of AH-550's from there to here at the much more moderate price of about $100USD.
Music Concrete in France has horns with similar profiles, made of concrete composite of course, at about twice the price (shipping included) as the Azurahorns. (The depressed USD/Euro ratio doesn't help here.) The quotes I've gotten from US-made wood horns are well above the Music Concrete price. A big attraction of the Azurahorn is the price is low enough to fall into what I consider the "experimental" range to play with different sizes and compression drivers. Not interested in small-format compression drivers, and don't need their HF extension since I already own supertweeters with complementary high efficiency, very low energy storage, and extension to 100 kHz.
Aside from shipping costs, I'm still going back and forth on the AH-340 vs the AH-550. The AH-340 (24" horn mouth diameter) is almost exactly twice as big as the AH-550 (12" diameter). The book by Newell and Dr. Holland recommends low-diffraction (no kinks in the acoustic path) horns with less than 12" of total length from diaphragm to horn-mouth. The authors point out that horns of this size and profile almost exactly mimic the 12" and 15" Tannoy Dual Concentrics, minus the weird modulation effects of the moving bass diaphragm.
This recommendation points towards the seven-inch-long AH-550, while the AH-340 offers the attractive option of a lower crossover and possibly lower distortion in the 1 kHz region. Essentially, a tradeoff between a 1:2 difference in energy storage (smaller horn, shorter delays, Tannoy dimensions) vs somewhat higher IM distortion from decreased diaphragm loading.
The arachnophobic approach to driver design
Lynn,
I think you've already decided on drivers, but one interesting thing to note is that the Be diaphragmed JBL 2435HPL has an internal flare rate of 550 Hz and the phase plug exits right at the throat. Perfect match for the 1.5" AZ-550.
A pal and I actually commissioned the above horn from Martin for Vitavox S2, which is also 1.5", but he may be able to supply an adaptor for it to take it down to 1.4" smoothly for the Altecs. I imagine most off the shelf adaptors to be hopelessly imprecise in terms of exact fit/transition.
We also sponsored the 160s... these are impressive looking beasts which should better match the flare rate of a whole generation of older drivers. Can't wait to try them out with the S2 and RCA field coils.
Look at the response plot of the Yamaha JA6681B on the 160Hz horn that's posted on Martin's site for example; never seen anything like it...
Incidentally, that driver has a wonderfully engineered surround formed of beryllium copper fingers which should hugely reduce diaphragm resonance - take a look.
I suspect the main advantage of compression drivers over cones is the omission of the spider; the Yam driver takes it further and removes much of the path for reflection of energy back into the diaphragm at the termination. The Fertin model 7 has similar design features; complex shaped carbon fiber spider (minimal hysteresis??) and a suspension of 3 thin carbon rods - see the fullrange forum for detail on this driver.
Anyway, enough rambling. Good luck and look forward to hearing your updates, as ever.
Best wishes,
Chris
Lynn,
I think you've already decided on drivers, but one interesting thing to note is that the Be diaphragmed JBL 2435HPL has an internal flare rate of 550 Hz and the phase plug exits right at the throat. Perfect match for the 1.5" AZ-550.
A pal and I actually commissioned the above horn from Martin for Vitavox S2, which is also 1.5", but he may be able to supply an adaptor for it to take it down to 1.4" smoothly for the Altecs. I imagine most off the shelf adaptors to be hopelessly imprecise in terms of exact fit/transition.
We also sponsored the 160s... these are impressive looking beasts which should better match the flare rate of a whole generation of older drivers. Can't wait to try them out with the S2 and RCA field coils.
Look at the response plot of the Yamaha JA6681B on the 160Hz horn that's posted on Martin's site for example; never seen anything like it...
Incidentally, that driver has a wonderfully engineered surround formed of beryllium copper fingers which should hugely reduce diaphragm resonance - take a look.
I suspect the main advantage of compression drivers over cones is the omission of the spider; the Yam driver takes it further and removes much of the path for reflection of energy back into the diaphragm at the termination. The Fertin model 7 has similar design features; complex shaped carbon fiber spider (minimal hysteresis??) and a suspension of 3 thin carbon rods - see the fullrange forum for detail on this driver.
Anyway, enough rambling. Good luck and look forward to hearing your updates, as ever.
Best wishes,
Chris
Lynn, where have you been!
...incredible thread!
I really love the way the thread flows and the amount of positive input the members have put in.
For the last 3 years, I have felt alone on an island with my open baffles and a 15" wideband 'till seeing this thread!!
Now, I will post pics soon of the system and my room but here goes by writing.
It is a 3 way open baffle on 3/4 inch russian birchply. I, like what I understood what from Lynn, like very much a 15" wideband driver for the weight it gives to instruments. Some will find this to be exagerated sound, but I find smaller drivers to be anemic. The wideband driver is an EV SP15A that has a 103db efficiency at 1Khz. I have added a fountek ribbon tweeter, the cd pro5i, that has an efficiency rating of 102 db. This is cutoff and I time phased it with the voice coil of the EV, with a mundorf cap of 3.3 mfd. This cuts it off at 5.6 Khz, well out of the critical spot. For bass, I have an Altec 515B on the open baffle and controlled by an active over. I reversed the phase of the Altec from the EV and adjusted the phase of the xover to 90 degrees. The active xover is a 3rd order xover, so I have a phase shift of 360 with the reverse phase and an 18 db slope. Also, it is time aligned with the voice coil of the EV.
The system is triamped, an amp for each driver.
Coherence was and is an important issue for me along with tone, effortless dynamics, agility, feel, textures and harmonic precision.
My shpeal on coherence is that a fullrange driver, such as a Lowther in a properly implimented system is the ultimate in coherence along with Acoustats. However, they are limited in FR and other things. I realise that as long as I am patching sound together again, I will never achieve the absolute coherence of such a driver. After listening to the Lowther in a highly optimised Big Fun Horn, I went back to my place in fear of finding a messy blob of sound. To my surprise, I was impressed that it didn't embarass my 3 way, and that the level of resolution was far superior to that of the Lowther DX4. I also, have better, IMO, development of the notes i.e harmonics.
My room, is 13 * 19 and is covered in russian birchply 1/2 inch. Velvet curtains on both ends, 1st 3 reflections aborbed and some absorption ever 2 feet.
I ask, since this Lynn's thread is basically based on the exact system I have except for the precise drivers mentioned, how you would first approch tuning this system for the better. Aspects such as energy storage, EnABL and diffraction methods amongst other ideas.
Tuning these beasts has been a lonely place for me, until seeing this thread, all inputs are more than welcomed. I have always wanted knowledgeable open baffle enthousiast help me improve my system.
Hopefully someone will respond to this post and I hope this post goes with the wonderful flow of this thread and not a thread fart. If it isn't right, I can repost it elsewhere.
Thanks,
Steve
...incredible thread!
I really love the way the thread flows and the amount of positive input the members have put in.
For the last 3 years, I have felt alone on an island with my open baffles and a 15" wideband 'till seeing this thread!!
Now, I will post pics soon of the system and my room but here goes by writing.
It is a 3 way open baffle on 3/4 inch russian birchply. I, like what I understood what from Lynn, like very much a 15" wideband driver for the weight it gives to instruments. Some will find this to be exagerated sound, but I find smaller drivers to be anemic. The wideband driver is an EV SP15A that has a 103db efficiency at 1Khz. I have added a fountek ribbon tweeter, the cd pro5i, that has an efficiency rating of 102 db. This is cutoff and I time phased it with the voice coil of the EV, with a mundorf cap of 3.3 mfd. This cuts it off at 5.6 Khz, well out of the critical spot. For bass, I have an Altec 515B on the open baffle and controlled by an active over. I reversed the phase of the Altec from the EV and adjusted the phase of the xover to 90 degrees. The active xover is a 3rd order xover, so I have a phase shift of 360 with the reverse phase and an 18 db slope. Also, it is time aligned with the voice coil of the EV.
The system is triamped, an amp for each driver.
Coherence was and is an important issue for me along with tone, effortless dynamics, agility, feel, textures and harmonic precision.
My shpeal on coherence is that a fullrange driver, such as a Lowther in a properly implimented system is the ultimate in coherence along with Acoustats. However, they are limited in FR and other things. I realise that as long as I am patching sound together again, I will never achieve the absolute coherence of such a driver. After listening to the Lowther in a highly optimised Big Fun Horn, I went back to my place in fear of finding a messy blob of sound. To my surprise, I was impressed that it didn't embarass my 3 way, and that the level of resolution was far superior to that of the Lowther DX4. I also, have better, IMO, development of the notes i.e harmonics.
My room, is 13 * 19 and is covered in russian birchply 1/2 inch. Velvet curtains on both ends, 1st 3 reflections aborbed and some absorption ever 2 feet.
I ask, since this Lynn's thread is basically based on the exact system I have except for the precise drivers mentioned, how you would first approch tuning this system for the better. Aspects such as energy storage, EnABL and diffraction methods amongst other ideas.
Tuning these beasts has been a lonely place for me, until seeing this thread, all inputs are more than welcomed. I have always wanted knowledgeable open baffle enthousiast help me improve my system.
Hopefully someone will respond to this post and I hope this post goes with the wonderful flow of this thread and not a thread fart. If it isn't right, I can repost it elsewhere.
Thanks,
Steve
Despite my woo-woo reputation, I mostly use instrumentation during the first part of a loudspeaker project, and listen to pink-noise, not music. I use MLSSA (or any other MLS system) and tune and/or modify the individual drivers for most rapid settling time (less than 1 mSec if possible), and then impulse-align the whole system after I am reasonably satisfied that the individual drivers are close to optimum performance.
Subjective fine-tuning happens after I am reasonably satisfied with the time and frequency domains, and is in small degrees, typically 1/2 dB trims between the drivers, as well as rolloff-slope optimization (which alters the polar pattern at crossover frequencies).
Subjective fine-tuning happens after I am reasonably satisfied with the time and frequency domains, and is in small degrees, typically 1/2 dB trims between the drivers, as well as rolloff-slope optimization (which alters the polar pattern at crossover frequencies).
Hi Lynn
Don't know if your last response was directed at me, but if it was I guess you are implying that without measurements you don't see anything to point to to "fine tune" my system.
I can get my measurements redone by my buddies with measuring devices...
How can I measure such a thing as diffraction?
Cheers
Steve
Don't know if your last response was directed at me, but if it was I guess you are implying that without measurements you don't see anything to point to to "fine tune" my system.
I can get my measurements redone by my buddies with measuring devices...
How can I measure such a thing as diffraction?
Cheers
Steve
I'd go with the smaller horn - the big one will beam and get in trouble on top, the ribbon won't mate well with it either. The smaller horns sound better with a compression driver
PS - have a real odd ball pair compression drivers here that's making me grin = some old cerwin vega phenolic 4" with 2" exit - really smooth and wonderful with strings - crossing in 500 with 12" tractrix, dies after 3 k but ohhhh the mids are dreamy
PS - have a real odd ball pair compression drivers here that's making me grin =
some old cerwin vega phenolic 4" with 2" exit - really smooth and wonderful with strings - crossing in 500 with 12" tractrix, dies after 3 k but ohhhh the mids are dreamyHello Lynn,
IMHO there is nearly no more diffraction with the Azura 340Hz horn than with the Azura 550Hz. A FEM simulation using hornresp will demonstrate it. (Also the mesured impedance curve is very smooth compared to the same driver on other horns, this is due to low difraction and refelected waves from the mouth to the throat).
For my own there is another reason why I prefer the larger horn it is because it's reactance is quasi null above 700Hz when the reactance of the 550 will still be non negligeible at 1000Hz.
Then about the increased directivity, that's a very personnal taste...
Best regards from Paris,
Jean-Michel Le Cléac'h
IMHO there is nearly no more diffraction with the Azura 340Hz horn than with the Azura 550Hz. A FEM simulation using hornresp will demonstrate it. (Also the mesured impedance curve is very smooth compared to the same driver on other horns, this is due to low difraction and refelected waves from the mouth to the throat).
For my own there is another reason why I prefer the larger horn it is because it's reactance is quasi null above 700Hz when the reactance of the 550 will still be non negligeible at 1000Hz.
Then about the increased directivity, that's a very personnal taste...
Best regards from Paris,
Jean-Michel Le Cléac'h
Lynn Olson said:
Hello,
A recent feature of Hornresp is the simulation of the wavefronts.
This is in:
[Tools]
[wavefront simulator]
I guess the calculation is done like in a wavetank simulator by Finite Elements Method...
But I may be wrong.
That wavefront simulator is a quite powerful tool to see the effect of the reflected waves from mouth to throat (but you need to wait something like one minute for the wavefield to stabilize).
Best regards from Paris, France
Jean-Michel Le Cléac'h
A recent feature of Hornresp is the simulation of the wavefronts.
This is in:
[Tools]
[wavefront simulator]
I guess the calculation is done like in a wavetank simulator by Finite Elements Method...
But I may be wrong.
That wavefront simulator is a quite powerful tool to see the effect of the reflected waves from mouth to throat (but you need to wait something like one minute for the wavefield to stabilize).
Best regards from Paris, France
Jean-Michel Le Cléac'h
ion said: