I'll make contact with Brown. I agree Lynn, there is just something "right" looking about those 18 Sound horns. The bigger 1" ones are spec'ed for 1.2 and 1.4 Khz. If we are crossing at over 3khz they should be at least big enough. and combined with those little BMS CD's that Lynn found would be economical enough to also get the AC ribbons to compare 
. These drivers are threaded though, which would require an adaptor, which they supply for $20 ea. Does this affect response? Also the price is now about the same as the next neo above, which has different charms. Maybe smoother, but not as much extension. Supravox used a very similar shape I believe for their horns, which I'm not sure they even sell anymore.
Speaking of Supravox, did we speak of them? If so , apologies
12"Alnico:
http://www.supravox.fr/anglais/haut_parleurs/285_2000.htm
12" Field Coil: "with oversize engine of excitation"
http://www.supravox.fr/anglais/haut_parleurs/285_2000_EXC.htm
They are sometimes hard to find I hear , and pretty expensive besides, and used to have quality control issues, but at least they are quite wide range...I think most of these issues are resolved. Anybody actually heard them?Probably Lynn has.. For the moment I like our home grown hemp drivers, but it's nice to have a back up option...
EDIT: Supravox recommends this tweeter for their open baffle
Nothing too distinguished looking about it. Might be an interesting thing to try with "full range" drivers as an alternative to Fostex supertweeters. Not for this project though
http://www.bcspeakers.com/download/prodotti/PDF/more/165.pdf
. These drivers are threaded though, which would require an adaptor, which they supply for $20 ea. Does this affect response? Also the price is now about the same as the next neo above, which has different charms. Maybe smoother, but not as much extension. Supravox used a very similar shape I believe for their horns, which I'm not sure they even sell anymore. Speaking of Supravox, did we speak of them? If so , apologies
12"Alnico:
http://www.supravox.fr/anglais/haut_parleurs/285_2000.htm
12" Field Coil: "with oversize engine of excitation"
http://www.supravox.fr/anglais/haut_parleurs/285_2000_EXC.htm
They are sometimes hard to find I hear , and pretty expensive besides, and used to have quality control issues, but at least they are quite wide range...I think most of these issues are resolved. Anybody actually heard them?Probably Lynn has.. For the moment I like our home grown
hemp drivers, but it's nice to have a back up option...EDIT: Supravox recommends this tweeter for their open baffle
Nothing too distinguished looking about it. Might be an interesting thing to try with "full range" drivers as an alternative to Fostex supertweeters. Not for this project though
http://www.bcspeakers.com/download/prodotti/PDF/more/165.pdf
Lynn Olson said:
It is interesting that we can have such different ways of hearing. It was listening to a female gospel choir on large Altecs that first got me interested in horns. They sounded so 3-d real and so tonally right.
I do think of horns as having a more front of the auditorium perspective, though. I like sitting near the front of the venue at a classical music concert. This was convenient when I lived in London because the front area was not the most expensive.
When I was a student in Boston, I liked to go to concerts at Symphony Hall. I'd buy a cheap student ticket, and about 10 minutes after the concert started, I'd creep up to an empty seat near the front. This worked well for a few years until one particular time. I moved forward, and was settling comfortably into my seat. Suddenly there was a wide woman in a fur coat glaring at me with an usher next to her. The usher said: "Mrs. Menuhin would like her seat." She was there to see her husband perform, and of course, I was in her place.
I like the sound of open baffles as well as horns, so please carry on... and continue to baffle us!
Supravox suggests a nice looking open baffle on this page:
http://www.supravox.fr/anglais/kits.htm#panneau
http://www.supravox.fr/anglais/kits.htm#panneau
Lynn Olson said:
Cappy said:
Similarly, I find these big horns do the most mind-blowing spatial tricks with big-scale electronica. There's a "hanging in a huge artificial space" thing that they do with certain recordings that is extremely enjoyable. It can be disorienting enough to force your eyes open at times!
Lynn Olson said:
I think this could be a good choice with the right driver. You absolutely must get a "pancake" style driver for these horns to work properly. If on a Constant Directivity horn like a conical or these OS shapes, you use a conventional driver that has a long throat section designed for older horns, this throat section forms a small HF horn that causes severe beaming while boosting the HF on-axis. The throat section of your compression driver ideally should conform to the expansion of the horn.
Others would be better able to direct you to new drivers built like this. I'm more into the old stuff.
Hi
well maybe perfection has it's price but on the other hand i didn't see so much first hand experiance postings with the mundorf exept this one:
http://www.diyaudio.com/forums/showthread.php?postid=1173214#post1173214
"http://www.diyaudio.com/forums/showthread.php?postid=1173214#post1173214"
so it may be just a (my) AMT hype?
I am currently listening to the ADAM Monitors P11a
http://www.adam-audio.com/studio/
"http://www.adam-audio.com/studio/"
which also have AMT or A.R.T. as they call it. They sound good , very open, and detailled and definitely can play loud but there is also something too bright on it. Maybe its rather from the swiched amp than from the AMT I didn't check that out in detail until now.
If someone wants to start it's own low cost production check out this page:
http://mywebpages.comcast.net/neilandbarbaradavis/DIYHeil/DIY1/index.htm
"http://mywebpages.comcast.net/neilandbarbaradavis/DIYHeil/DIY1/index.htm"
Greetings
Michael
well maybe perfection has it's price but on the other hand i didn't see so much first hand experiance postings with the mundorf exept this one:
http://www.diyaudio.com/forums/showthread.php?postid=1173214#post1173214
"http://www.diyaudio.com/forums/showthread.php?postid=1173214#post1173214"
so it may be just a (my) AMT hype?
I am currently listening to the ADAM Monitors P11a
http://www.adam-audio.com/studio/
"http://www.adam-audio.com/studio/"
which also have AMT or A.R.T. as they call it. They sound good , very open, and detailled and definitely can play loud but there is also something too bright on it. Maybe its rather from the swiched amp than from the AMT I didn't check that out in detail until now.
If someone wants to start it's own low cost production check out this page:
http://mywebpages.comcast.net/neilandbarbaradavis/DIYHeil/DIY1/index.htm
"http://mywebpages.comcast.net/neilandbarbaradavis/DIYHeil/DIY1/index.htm"
Greetings
Michael
Hi Lynn,
A ToneTubby 8" with a more robust cast frame/basket rather than stamped steel would be interesting to measure...
FAL of Japan has a flat type of widerange neodymium driver (Flat C-90 95db/w/m) but is said to be beamy af HF. Pricey for a pair I think but is said to be very good in OB. Maybe you could xo it in the lower hf ~6kHz? FAL also makes their own high eff Heil tweeters to mate with their widerangers, which might be as pricey as those Mundorfs.
Anyways wrt horns, Jean-Michel LC's horns at the ETF 2004 are pretty much the same as the Azurahorns as they use the same expansion, except for the material used. I think JMLC uses horns that use a form of plaster material.
http://ndaviden.club.fr/pavillon/exemples/photos320.html
Jefferey Jackson of experiencemusic.net also has samples of his own made Le C'leach expansion 320Hz horns (t'was at RMAF). Maybe he can lend you his pair? Jefferey used slagleformer attenuators for the compression drivers. The Fostex autoformers (1dB steps) are quite on the pricey side.
For narrow width listening rooms, I think a pair of "very good" horns would be a good thing to avoid early reflections from sidewalls. Even if using small format compression drivers, and if let's say a phenolic diaphragm (vintage driver) that limits the HF ~8k natural roll off, one could still augment it a with a very good supertweeter.
A ToneTubby 8" with a more robust cast frame/basket rather than stamped steel would be interesting to measure...
FAL of Japan has a flat type of widerange neodymium driver (Flat C-90 95db/w/m) but is said to be beamy af HF. Pricey for a pair I think but is said to be very good in OB. Maybe you could xo it in the lower hf ~6kHz? FAL also makes their own high eff Heil tweeters to mate with their widerangers, which might be as pricey as those Mundorfs.
Anyways wrt horns, Jean-Michel LC's horns at the ETF 2004 are pretty much the same as the Azurahorns as they use the same expansion, except for the material used. I think JMLC uses horns that use a form of plaster material.
http://ndaviden.club.fr/pavillon/exemples/photos320.html
Jefferey Jackson of experiencemusic.net also has samples of his own made Le C'leach expansion 320Hz horns (t'was at RMAF). Maybe he can lend you his pair? Jefferey used slagleformer attenuators for the compression drivers. The Fostex autoformers (1dB steps) are quite on the pricey side.
For narrow width listening rooms, I think a pair of "very good" horns would be a good thing to avoid early reflections from sidewalls. Even if using small format compression drivers, and if let's say a phenolic diaphragm (vintage driver) that limits the HF ~8k natural roll off, one could still augment it a with a very good supertweeter.
Thanks for the link JC Fardo.
This is the last from Lukasz' website;-
http://www.lampizator.eu/SPEAKERS/PROJECTS/P19/P19 alnico open baffle.html
Cheers ........ Graham.
This is the last from Lukasz' website;-
http://www.lampizator.eu/SPEAKERS/PROJECTS/P19/P19 alnico open baffle.html
Cheers ........ Graham.
I have been reading this thread with great interest from the beginning. Thanks to all who have contributed as I am learning alot.
I have only built home systems so far with cones and domes plus a couple full range 12" guitar cabinets but I have been interested in open baffles and other "outside the box" ideas for a long time. Full range speakers with no crossover in the midrange intrigue me. My family is full of DIY stereo nuts so I'ved heard a lot of different types of speakers over the years. I've also heard electrostatics, B&W 801's, plenty of PA's from my rock band years, wall mounted studio monitors, nearfield monitors...... My preference for home stereo, so far, is a good three way with 12" sealed woofer, 7" to 5" midrange, and 1" dome. I like my sealed boxes with a .7 system Q and I like minimal crossovers with time aligned cabinets with minimal baffles for low diffraction. My current system is a 801, Vandersteen type thing with a top mount Morel tweeter. I do not like horns. But I do like PA type dynamics. I find textbook Canadian speakers boring and love phase coherent Theil/Vandersteen type speakers. Always wanted to hear a Dalquist model ten, or whatever the classic one was. I like electrostatics at low volume and I like wide open guitar speakers with my guitar and tube amps.
Just giving some backround before I give my opinion.
Lynn, having read this thread and EVERYTHING on your website(which is awesome, by the way) I can't see you liking a horn tweeter of any kind. I agree with everything you are trying to achieve with this project and I think ribbon is the way to go. Electrostatic like open sound with more SPL's can be achieved by a big paper open baffle midrange. In my opinion, not with a horn. They just don't have that kind of low coloration or dispersion to ever have an open sound. And I think the idea of using two ribbons for dipole output seems like slam dunk.
Based on what I have experienced there is plenty of potential in your midrange idea. I've heard it with my own ears how good a 8" to 12" pro speaker can sound. I have never heard a horn or compression driver that I thought sounded like high end anything. No open, no airy, no good outside the sweet spot......
Anyway, thats my opinion, carry on!
I have only built home systems so far with cones and domes plus a couple full range 12" guitar cabinets but I have been interested in open baffles and other "outside the box" ideas for a long time. Full range speakers with no crossover in the midrange intrigue me. My family is full of DIY stereo nuts so I'ved heard a lot of different types of speakers over the years. I've also heard electrostatics, B&W 801's, plenty of PA's from my rock band years, wall mounted studio monitors, nearfield monitors...... My preference for home stereo, so far, is a good three way with 12" sealed woofer, 7" to 5" midrange, and 1" dome. I like my sealed boxes with a .7 system Q and I like minimal crossovers with time aligned cabinets with minimal baffles for low diffraction. My current system is a 801, Vandersteen type thing with a top mount Morel tweeter. I do not like horns. But I do like PA type dynamics. I find textbook Canadian speakers boring and love phase coherent Theil/Vandersteen type speakers. Always wanted to hear a Dalquist model ten, or whatever the classic one was. I like electrostatics at low volume and I like wide open guitar speakers with my guitar and tube amps.
Just giving some backround before I give my opinion.
Lynn, having read this thread and EVERYTHING on your website(which is awesome, by the way) I can't see you liking a horn tweeter of any kind. I agree with everything you are trying to achieve with this project and I think ribbon is the way to go. Electrostatic like open sound with more SPL's can be achieved by a big paper open baffle midrange. In my opinion, not with a horn. They just don't have that kind of low coloration or dispersion to ever have an open sound. And I think the idea of using two ribbons for dipole output seems like slam dunk.
Based on what I have experienced there is plenty of potential in your midrange idea. I've heard it with my own ears how good a 8" to 12" pro speaker can sound. I have never heard a horn or compression driver that I thought sounded like high end anything. No open, no airy, no good outside the sweet spot......
Anyway, thats my opinion, carry on!
Graham Maynard said:
Too bad the woofer he seems to favour - the Alphard RW 1800 ($174 USD or 480 PLN) seems to be out of production or at least out of stock.
http://www.alphard.pl/products/29
I don't read Polish and the English part of the site is briefer.
MONACOR....
I've just stumbled on the monacor pro range, and man do they seem to be very well made.
Die cast baskets, treated paper etc, etc, as you would expect.
Notional sensitivity of the 12" upwards of 97 db/W !
Of note is the SP38A 300PA... nice flat FR...
Impedance (Z) 8Ω
Resonant frequency (fs) 48Hz
Max. frequency range f3-4,000Hz
Rec. crossover freq. (fmax.) 1,100Hz
Music power 1,200WMAX
Power rating (P) 300WRMS
SPL (1W/1m) 102dB
Suspension compl. (Cms) 0.09mm/N
Moving mass (Mms) 100g
Mech. resistance (Rms) 4.4kg/s
Mech. Q factor (Qms) 7.45
Electr. Q factor (Qes) 0.31
Total Q factor (Qts) 0.29
Equivalent volume (Vas) 101 l
DC resistance (Re) 5.4Ω
Voice coil induct. (Le) 1.3mH
Voice coil diameter 76mm
Voice coil former glass fiber
Voice coil winding height 18.5mm
Air gap height 9mm
Linear excursion (XMAX) ±4.8mm
Eff. cone area (Sd) 880cm2
Volume displacement (Vd) 422cm3
Force factor (BxL) 24,1Tm
Reference efficiency (No) 4.8%
Magnet diameter 200mm
Magnet weight 90oz.
Mounting cutout Ø 360mm
Mounting depth 172mm
Dimensions Ø 391mm
Weight 8.5kg
Rec. net cabinet volume
Closed -
Bass-reflex approx. 75 l
Has any-one heard these...? Could be just the ticket, combined with a nice tweet, for a killer 2 way....
Just a thought
Owen
I've just stumbled on the monacor pro range, and man do they seem to be very well made.
Die cast baskets, treated paper etc, etc, as you would expect.
Notional sensitivity of the 12" upwards of 97 db/W !
Of note is the SP38A 300PA... nice flat FR...
Impedance (Z) 8Ω
Resonant frequency (fs) 48Hz
Max. frequency range f3-4,000Hz
Rec. crossover freq. (fmax.) 1,100Hz
Music power 1,200WMAX
Power rating (P) 300WRMS
SPL (1W/1m) 102dB
Suspension compl. (Cms) 0.09mm/N
Moving mass (Mms) 100g
Mech. resistance (Rms) 4.4kg/s
Mech. Q factor (Qms) 7.45
Electr. Q factor (Qes) 0.31
Total Q factor (Qts) 0.29
Equivalent volume (Vas) 101 l
DC resistance (Re) 5.4Ω
Voice coil induct. (Le) 1.3mH
Voice coil diameter 76mm
Voice coil former glass fiber
Voice coil winding height 18.5mm
Air gap height 9mm
Linear excursion (XMAX) ±4.8mm
Eff. cone area (Sd) 880cm2
Volume displacement (Vd) 422cm3
Force factor (BxL) 24,1Tm
Reference efficiency (No) 4.8%
Magnet diameter 200mm
Magnet weight 90oz.
Mounting cutout Ø 360mm
Mounting depth 172mm
Dimensions Ø 391mm
Weight 8.5kg
Rec. net cabinet volume
Closed -
Bass-reflex approx. 75 l
Has any-one heard these...? Could be just the ticket, combined with a nice tweet, for a killer 2 way....
Just a thought
Owen
Hi guys, I've been lurking in the shadows on this one too. The goals here of a high-efficiency dipole are pretty consistant with what I've been trying to accomplish as well. I had stayed away from the large (>8") wideband/midrange though, thinking that the directivity might be an issue. However, some playing around with an old Hartley system I have around here turned up some pretty good subjective results.
This old Hartley is a 3 way 7" tweeter, 10" mid, 24" dipole woofer. The slam from the 24 is really unbelievable, and the mids are awesome, but the highs were lacking. I plopped an AMT tweeter on top of this monstrosity and crossed it actively with a behringer DCX9624 at around 2000. Really, really nice sound, save the static from the behringer which kinda ruined everything. Before everyone thinks I should be posting in another forum, I am trying to make a point here. The point being, to my ears at least, the combo of an AMT tweeter, a 10" widerange mid, and a large dipole woofer really seems to do everything right.
My question is, has anyone contemplated a really large woofer for bass? Something like this perhaps. My thoughts are that a decent 10"-12" that could hold itself together down to around 200 hz on a 22-24" wide baffle (like a 12NDA520), crossed on the bottom end to something like that monster 20" and on the top to a ribbon or an AMT would be a modern equivalent to that monstrosity I was playing with. I realize a 20" woofer isn't going to be eveyone's solution, but for those with the room, I think it might be great.
This old Hartley is a 3 way 7" tweeter, 10" mid, 24" dipole woofer. The slam from the 24 is really unbelievable, and the mids are awesome, but the highs were lacking. I plopped an AMT tweeter on top of this monstrosity and crossed it actively with a behringer DCX9624 at around 2000. Really, really nice sound, save the static from the behringer which kinda ruined everything. Before everyone thinks I should be posting in another forum, I am trying to make a point here. The point being, to my ears at least, the combo of an AMT tweeter, a 10" widerange mid, and a large dipole woofer really seems to do everything right.
My question is, has anyone contemplated a really large woofer for bass? Something like this perhaps. My thoughts are that a decent 10"-12" that could hold itself together down to around 200 hz on a 22-24" wide baffle (like a 12NDA520), crossed on the bottom end to something like that monster 20" and on the top to a ribbon or an AMT would be a modern equivalent to that monstrosity I was playing with. I realize a 20" woofer isn't going to be eveyone's solution, but for those with the room, I think it might be great.
Follow up to Owens link.
Agent in UK - Henry's Electronics, Edgeware Rd., London.
http://www.monacor.com/int/en/produktseite_gesamtprogramm.php?artid=67&spr=EN&typ=u
http://www.monacor.com/int/en/produktseite_gesamtprogramm.php?artid=6432&spr=EN&typ=u
http://www.monacor.com/int/en/produktseite_gesamtprogramm.php?artid=4271&spr=EN&typ=u
Cheers ...... Graham.
Agent in UK - Henry's Electronics, Edgeware Rd., London.
http://www.monacor.com/int/en/produktseite_gesamtprogramm.php?artid=67&spr=EN&typ=u
http://www.monacor.com/int/en/produktseite_gesamtprogramm.php?artid=6432&spr=EN&typ=u
http://www.monacor.com/int/en/produktseite_gesamtprogramm.php?artid=4271&spr=EN&typ=u
Cheers ...... Graham.
I had a look at the FR plot for the new TT 8" today; while not ideal, it looks pretty darn good overall, Fs=50, Qts=.707, avge. SPL 93db/500-2.5KHz, and the most interesting aspect is the fact that it extends out to ~8.5KHz. With active contouring or not, I think this would make a stunning fill driver for a scaled-down version of whatever is concluded upon here. This driver is almost 1/3 the price of the Alnico 10"...
I had asked TT at NAMM to please in future publish independent measurements, as inquiring minds would want to know, and they seem to have done this as well with their smaller DIA stuff on the www.abrown.com site. Good work. These guys listen, and have a speaker developer here in SD Cty working on various alignments.
I had asked TT at NAMM to please in future publish independent measurements, as inquiring minds would want to know, and they seem to have done this as well with their smaller DIA stuff on the www.abrown.com site. Good work. These guys listen, and have a speaker developer here in SD Cty working on various alignments.
The Story So Far, Part II
I love this quote from the website:
"On the back side there is NOTHING. No rocket science is required. Super materials, advanced box calculations, stiffening, lead-clad dampening, matrix systems, snail-like Nautilus shells - all can be left for the HIFI rags to rave about. We don't need that and this is the best news I am bringing to you."
Yup. The best cabinet is NO cabinet. You hear the drivers as they are, naked, direct, no murk and cloudiness from a high-mass cabinet filled with all kinds of damping junk with mysterious colorations of their own. As mainstream high-end speakers have gotten heavier and heavier, made from more and more exotic materials, it's been difficult not to notice that they sound worse and worse, more and more unnatural and un-musical.
The flip side is the drivers have to be good, since the cabinet isn't covering things up anymore. Which leads me to Part Two of the continuing story ...
-----------
HF: BMS 4540ND or 4552ND ring-radiator 1" compression drivers, with preference to the 4540ND. There are several interesting horns: 18Sound XT1086, Azurahorn AH-550, the US$7 PHR-1200 from Music Supply Center, or similar size horns with oblate spheroid/elliptical or Le Cleac'h profiles. (Note the XT1086 is 5" deep and 8.5" H x 10.2" W, the AH-550 is 8" deep and 12" diameter, and the PHR-1200 is 5.4" deep and 11.4" diameter. An excellent set of measurements and modifications of the PHR-1200 have been made by PaulW.)
Or high-efficiency ribbons or AMT's, seasoned to taste. No matter what tweeter you choose, it should be able to keep up with the dynamics of the rest of the system. This means very low distortion, especially in the 1.5 to 5 kHz region, and lots of headroom. By "headroom" I mean not just surviving, but sailing easily through 110~115 dB.
Highpass filter somewhere between 2 ~ 3 kHz, slope 12 to 24 dB/octave, depending on what meshes best with the widerange 12" driver. Adjust the free-standing horn for approximate time-alignment (by measurement in the time domain), then adjust the crossovers from the widerange driver and the tweeter for an in-phase relationship, to be confirmed by temporary phase-reversal on the tweeter and looking for a null of at least 20 dB. It is also highly desirable for the skirts of the null to be smooth and free of "bumps" in the crossover region - this assures smooth phase hand-off from one driver to the next, and gives a pleasing coherent quality to the crossover region.
Widerange: 18Sound 12NDA520. Yes, I've been wanting to use this driver, because of the superb technology - good choice of cone material and profile, and a state-of-the-art magnetic system. This is one of the best-measuring prosound drivers I've seen - and I think the midrange and upper-midrange performance of the driver is very likely to be noticeably better than the Alnico Tone Tubby, with a cleaner, less vintage, more open sound.
There should be a 1st-order lowpass filter coming in around 1.5~1.8 kHz, possibly steepening to 2nd-order around 3 kHz - or in other words, a low-Q 2nd/order filter around 2 kHz. A highpass filter around 125 to 200 Hz is optional, although finding good-sounding caps in that value is going to be almost impossible. If you're going to multi-amp, though, a highpass setting in that range would probably be a good starting point.
Midbass: 12" Alnico Tone Tubby in 16-ohm version. The midbass region is where the combination of Alnico and the big hemp cone really shines, with vivid, dynamic tone colors. I see no problem running the 18Sound and TT together - the 12NDA520 uses a "high-damping" curvilinear wood pulp paper cone, a traditional material that should mesh with the TT just fine.
The midbass driver should share the 2 kHz lowpass filter of the 12NDA520, and have an additional 6 dB/octave filter somewhere between 160 and 250 Hz, compensating for the 1/f dipole loss of the 12NDA520. A tapped inductor is a good way to tune the midbass driver to the room.
Bass: 15" Tone Tubby in 16-ohm version, or any other 15, 18, or larger high-Q traditionally-built bass driver. This is mounted with the edge of the driver close to the floor, with the bass module (if separate) having swept side wings (drawing to come). Big Is Good for this frequency range and application. (C'mon down, Hartley fans! Join the party!)
The bass driver should share the 2 kHz lowpass filter of the 12NDA520, and have an additional 6 dB/octave filter between 80 and 125 Hz. Maybe it should also share the 160~250 Hz lowpass filter of the midbass driver - this to be determined by measurement and audition.
The widerange, midbass, and bass drivers are all connected in parallel at the lowest frequencies, giving an effective 4-ohm impedance below 50 Hz. Any competently designed amplifier, including 45 and 2A3 SET's, should drive the speaker with no problems - that's what the 4-ohm tap on the output transformer is for, after all. Discounting the 1/f loss, the 3 bass drivers working in parallel have an efficiency of 106 dB/metre! In practice, I expect the overall system efficiency to be similar to the 12NDA520's Theile/Small efficiency of 99 dB/metre.
This system is the one I like the most. It has an interesting philosophy of the most vintage sound in the bass region, gradually transitioning to a more modern sound as you get to the midrange and higher frequencies. This aligns with my own personal preferences - I like vintage bass, but don't care for vintage upper-mids or treble, where the old-school colorations become intrusive and detract from the listening experience. But I really like the traditional big-bass sound of efficient 12 and 15-inch drivers with paper cones.
Keeping the horn tweeter transition to the 2~3 kHz region leaves the mids to the big cone driver, something I want to do. Looking closely at the 12NDA520, it looks considerably better behaved than its 10-inch cousins, the 10NDA520 and 10NDA610. Since all of the A-series models are ultralow inductance drivers, we're really seeing what the cones are doing, instead of the usual rolling off and masking from the self-inductance of traditional high-inductance woofers (like the Tone Tubby's).
-------------
System Three? The same, except with a coaxial driver replacing the BMS tweeter and 12NDA520. The best coaxials appear to be the 12-inch Hemp Acoustics, the Radians, maybe the BMS models, and the ceiling-mount 12" paper-cone Tannoy. Sophisticated crossover design will be needed to smooth out the cone-driver response and match it with the fixed-distance tweeter.
The reason I'm bring up the 3-driver approach for Systems Two and Three is that I feel that modern low-Q widerange drivers are going to need more support in the bass and midbass region, and using 2 high-Q drivers is the way to get it, while keeping requirements for equalization and cone excursion modest. The first system with the ribbon + 12" TT + 15" TT can be described as a 2.5 way system, while the systems Two and Three in this Special DVD Edition posting can be described as 2.5.5 way systems, with two fractional crossovers spaced about an octave apart.
In terms of multi-amping, there are two approaches: bi-amping, with a dedicated amp + subwoofer in the 20 Hz through 60~80 Hz range, and separate high-quality amp for the 80 Hz through 30 kHz range.
Or alternatively, three amps, with a dedicated amp + subwoofer, a crossover + equalizer + midbass amp for the Tone Tubby's, and a high-quality amp for the MF/HF drivers.
Graham Maynard said:
I love this quote from the website:
"On the back side there is NOTHING. No rocket science is required. Super materials, advanced box calculations, stiffening, lead-clad dampening, matrix systems, snail-like Nautilus shells - all can be left for the HIFI rags to rave about. We don't need that and this is the best news I am bringing to you."
Yup. The best cabinet is NO cabinet. You hear the drivers as they are, naked, direct, no murk and cloudiness from a high-mass cabinet filled with all kinds of damping junk with mysterious colorations of their own. As mainstream high-end speakers have gotten heavier and heavier, made from more and more exotic materials, it's been difficult not to notice that they sound worse and worse, more and more unnatural and un-musical.
The flip side is the drivers have to be good, since the cabinet isn't covering things up anymore. Which leads me to Part Two of the continuing story ...
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HF: BMS 4540ND or 4552ND ring-radiator 1" compression drivers, with preference to the 4540ND. There are several interesting horns: 18Sound XT1086, Azurahorn AH-550, the US$7 PHR-1200 from Music Supply Center, or similar size horns with oblate spheroid/elliptical or Le Cleac'h profiles. (Note the XT1086 is 5" deep and 8.5" H x 10.2" W, the AH-550 is 8" deep and 12" diameter, and the PHR-1200 is 5.4" deep and 11.4" diameter. An excellent set of measurements and modifications of the PHR-1200 have been made by PaulW.)
Or high-efficiency ribbons or AMT's, seasoned to taste. No matter what tweeter you choose, it should be able to keep up with the dynamics of the rest of the system. This means very low distortion, especially in the 1.5 to 5 kHz region, and lots of headroom. By "headroom" I mean not just surviving, but sailing easily through 110~115 dB.
Highpass filter somewhere between 2 ~ 3 kHz, slope 12 to 24 dB/octave, depending on what meshes best with the widerange 12" driver. Adjust the free-standing horn for approximate time-alignment (by measurement in the time domain), then adjust the crossovers from the widerange driver and the tweeter for an in-phase relationship, to be confirmed by temporary phase-reversal on the tweeter and looking for a null of at least 20 dB. It is also highly desirable for the skirts of the null to be smooth and free of "bumps" in the crossover region - this assures smooth phase hand-off from one driver to the next, and gives a pleasing coherent quality to the crossover region.
Widerange: 18Sound 12NDA520. Yes, I've been wanting to use this driver, because of the superb technology - good choice of cone material and profile, and a state-of-the-art magnetic system. This is one of the best-measuring prosound drivers I've seen - and I think the midrange and upper-midrange performance of the driver is very likely to be noticeably better than the Alnico Tone Tubby, with a cleaner, less vintage, more open sound.
There should be a 1st-order lowpass filter coming in around 1.5~1.8 kHz, possibly steepening to 2nd-order around 3 kHz - or in other words, a low-Q 2nd/order filter around 2 kHz. A highpass filter around 125 to 200 Hz is optional, although finding good-sounding caps in that value is going to be almost impossible. If you're going to multi-amp, though, a highpass setting in that range would probably be a good starting point.
Midbass: 12" Alnico Tone Tubby in 16-ohm version. The midbass region is where the combination of Alnico and the big hemp cone really shines, with vivid, dynamic tone colors. I see no problem running the 18Sound and TT together - the 12NDA520 uses a "high-damping" curvilinear wood pulp paper cone, a traditional material that should mesh with the TT just fine.
The midbass driver should share the 2 kHz lowpass filter of the 12NDA520, and have an additional 6 dB/octave filter somewhere between 160 and 250 Hz, compensating for the 1/f dipole loss of the 12NDA520. A tapped inductor is a good way to tune the midbass driver to the room.
Bass: 15" Tone Tubby in 16-ohm version, or any other 15, 18, or larger high-Q traditionally-built bass driver. This is mounted with the edge of the driver close to the floor, with the bass module (if separate) having swept side wings (drawing to come). Big Is Good for this frequency range and application. (C'mon down, Hartley fans! Join the party!)
The bass driver should share the 2 kHz lowpass filter of the 12NDA520, and have an additional 6 dB/octave filter between 80 and 125 Hz. Maybe it should also share the 160~250 Hz lowpass filter of the midbass driver - this to be determined by measurement and audition.
The widerange, midbass, and bass drivers are all connected in parallel at the lowest frequencies, giving an effective 4-ohm impedance below 50 Hz. Any competently designed amplifier, including 45 and 2A3 SET's, should drive the speaker with no problems - that's what the 4-ohm tap on the output transformer is for, after all. Discounting the 1/f loss, the 3 bass drivers working in parallel have an efficiency of 106 dB/metre! In practice, I expect the overall system efficiency to be similar to the 12NDA520's Theile/Small efficiency of 99 dB/metre.
This system is the one I like the most. It has an interesting philosophy of the most vintage sound in the bass region, gradually transitioning to a more modern sound as you get to the midrange and higher frequencies. This aligns with my own personal preferences - I like vintage bass, but don't care for vintage upper-mids or treble, where the old-school colorations become intrusive and detract from the listening experience. But I really like the traditional big-bass sound of efficient 12 and 15-inch drivers with paper cones.
Keeping the horn tweeter transition to the 2~3 kHz region leaves the mids to the big cone driver, something I want to do. Looking closely at the 12NDA520, it looks considerably better behaved than its 10-inch cousins, the 10NDA520 and 10NDA610. Since all of the A-series models are ultralow inductance drivers, we're really seeing what the cones are doing, instead of the usual rolling off and masking from the self-inductance of traditional high-inductance woofers (like the Tone Tubby's).
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System Three? The same, except with a coaxial driver replacing the BMS tweeter and 12NDA520. The best coaxials appear to be the 12-inch Hemp Acoustics, the Radians, maybe the BMS models, and the ceiling-mount 12" paper-cone Tannoy. Sophisticated crossover design will be needed to smooth out the cone-driver response and match it with the fixed-distance tweeter.
The reason I'm bring up the 3-driver approach for Systems Two and Three is that I feel that modern low-Q widerange drivers are going to need more support in the bass and midbass region, and using 2 high-Q drivers is the way to get it, while keeping requirements for equalization and cone excursion modest. The first system with the ribbon + 12" TT + 15" TT can be described as a 2.5 way system, while the systems Two and Three in this Special DVD Edition posting can be described as 2.5.5 way systems, with two fractional crossovers spaced about an octave apart.
In terms of multi-amping, there are two approaches: bi-amping, with a dedicated amp + subwoofer in the 20 Hz through 60~80 Hz range, and separate high-quality amp for the 80 Hz through 30 kHz range.
Or alternatively, three amps, with a dedicated amp + subwoofer, a crossover + equalizer + midbass amp for the Tone Tubby's, and a high-quality amp for the MF/HF drivers.