Variac,
Thanks for that link. Only 50 pieces means I only have to commit to 13pairs, maybe less as a coax. My problem is geography. While I may be able to develop some proficiency at measurements and XO design, experience is better, and me wasting many $100s on shipping in the prototype process defeats the purpose. Anyone who is interested in being the stateside coordinator, please contact me directly. I have the business requirements and financial guarantee to Eminence covered.
Thanks for that link. Only 50 pieces means I only have to commit to 13pairs, maybe less as a coax. My problem is geography. While I may be able to develop some proficiency at measurements and XO design, experience is better, and me wasting many $100s on shipping in the prototype process defeats the purpose. Anyone who is interested in being the stateside coordinator, please contact me directly. I have the business requirements and financial guarantee to Eminence covered.
johninCR said:
Fair enough, but I thought that the delays with the 10" were more due to Darrel's satisfaction with getting it to sound quite right, as opposed to any production issues by Eminence.
The bases-loaded home-run that was achieved with the original SI15, ( with relatively minor revisions to the passive XO), turned out to be a tough act to follow.
As for Darrel's profit margin, at his current retail pricing I doubt he's paying for the lease on a Lamborghini
John,
I travel, to Costa Rica at least once a year, as you know. Next trip: early July, so am happy to be a mule. But I understand that you want someone with a proven ear to actually work with Eminence..someone like Lynn!!!
Working with SI is still a good idea IMHO-maybe they would give us a deal for the first run. Let their travails getting a great 10" be a lesson, you can't just order this stuff by the book and expect something great.(I know you know this..)
Here is another guy with a successful audiophile custom driver:
http://www.bd-design.nl/
Look for the BD-15
LYNN: Shall I split all references to getting a custom driver off into its own thread?
I travel, to Costa Rica at least once a year, as you know. Next trip: early July, so am happy to be a mule. But I understand that you want someone with a proven ear to actually work with Eminence..someone like Lynn!!!
Working with SI is still a good idea IMHO-maybe they would give us a deal for the first run. Let their travails getting a great 10" be a lesson, you can't just order this stuff by the book and expect something great.(I know you know this..)
Here is another guy with a successful audiophile custom driver:
http://www.bd-design.nl/
Look for the BD-15
LYNN: Shall I split all references to getting a custom driver off into its own thread?
Info about my personal situation: it'll probably be months before I can go down into the basement and use MLSSA to measure things, or re-assemble my Karna amplifiers so I can listen to quality hi-fi. My Ariels are connected to my Denon HT receiver, which is only barely hi-fi, and hardly a serious evaluation tool. Things are going to stay that way until I'm well along in the rehab program and can actually walk around, go up and down stairs, and carry things while walking.
I started the thread precisely because I can't do my usual design thing quietly by myself, so I'm throwing it open to all of you - and I very much appreciate your co-operation and great suggestions. But for now, you guys are on your own with the actual baffle-building, measurements, and auditions - it'll probably be summertime 'till I can do that kind of thing.
As for preferred driver sizes, I give a big vote to partitioning things into favorite driver sizes, probably 8" and 12" drivers. A speaker with a 8" fullranger is a very different animal than a speaker with a 12" fullranger - but fortunately, the underlying technology and overall approach is very much the same, consisting of a diffraction-controlled open baffle, a fullrange/widerange driver on top, and one or more bass-augmentation units on the bottom. There are wings on the bottom part of the OB, and no wings on the top. The LF crossover can be active or passive, as desired, with LF EQ to taste.
As for ribbons mounted coaxially, well it would work, I guess, but I'm concerned about the nearly massless ribbon fluttering under pressure from the bass waves from the driver. Pressures are highest in the middle of the cone, and that's right where the ribbon would go - I think IM distortion might be a problem for the tweeter when serious bass comes along.
I wouldn't go chasing the will-o-the-wisp of Siegfried's latest confections. Like me, he changes his mind all the time, and like my stuff, his speakers (which I've heard) have good and bad points sonically. I've heard dipole and cardioid speakers and well, yes, they have good points, but I really think the absence of the cabinet is the big thing, not the polar pattern, which is very much a room-sensitivity thing. Some rooms may favor cardioids, and some may favor dipoles. MBLs and Bastanis speakers both do wonderful things, but they are completely different animals as far as radiation patterns go.
As for another spinning off another thread, maybe one entitled "Advanced Coax Design"?
I started the thread precisely because I can't do my usual design thing quietly by myself, so I'm throwing it open to all of you - and I very much appreciate your co-operation and great suggestions. But for now, you guys are on your own with the actual baffle-building, measurements, and auditions - it'll probably be summertime 'till I can do that kind of thing.
As for preferred driver sizes, I give a big vote to partitioning things into favorite driver sizes, probably 8" and 12" drivers. A speaker with a 8" fullranger is a very different animal than a speaker with a 12" fullranger - but fortunately, the underlying technology and overall approach is very much the same, consisting of a diffraction-controlled open baffle, a fullrange/widerange driver on top, and one or more bass-augmentation units on the bottom. There are wings on the bottom part of the OB, and no wings on the top. The LF crossover can be active or passive, as desired, with LF EQ to taste.
As for ribbons mounted coaxially, well it would work, I guess, but I'm concerned about the nearly massless ribbon fluttering under pressure from the bass waves from the driver. Pressures are highest in the middle of the cone, and that's right where the ribbon would go - I think IM distortion might be a problem for the tweeter when serious bass comes along.
I wouldn't go chasing the will-o-the-wisp of Siegfried's latest confections. Like me, he changes his mind all the time, and like my stuff, his speakers (which I've heard) have good and bad points sonically. I've heard dipole and cardioid speakers and well, yes, they have good points, but I really think the absence of the cabinet is the big thing, not the polar pattern, which is very much a room-sensitivity thing. Some rooms may favor cardioids, and some may favor dipoles. MBLs and Bastanis speakers both do wonderful things, but they are completely different animals as far as radiation patterns go.
As for another spinning off another thread, maybe one entitled "Advanced Coax Design"?
mikey_audiogeek said:Not if you take the back off the compression drivers to expose the diaphragm for dipole operation, like I (and others) have...
Does anyone have experience or data on running a compression driver with the back chamber and dampening material removed? It would be an interesting experiment to run both a front and rear horn, or lower loading waveguides, from one compression driver.
The Orion forum noted that a second Seas tweeter is necessary because testing showed that removing the rear compression chamber dramatically changed the response curve and also raised the useful crossover frequency.
I don't think you would want to use a ribbon as the coaxial tweeter element, but rather get the xover low enough to dipole mount it above the dipole mid-bass on the baffle. The Raven 3 has a Fs of 500Hz, and a DIY dipole ribbon should be able to match this. Just another idea in case the dipole compression driver in the coaxial fails to work out.
how about this one?
http://www.assistanceaudio.com/15_Assaudcoaxial.html
it uses the BMS 4552ND driver which is suppose to be a seriously bad@$$ CD. Ciare is no slouch either.
http://www.assistanceaudio.com/15_Assaudcoaxial.html
it uses the BMS 4552ND driver which is suppose to be a seriously bad@$$ CD. Ciare is no slouch either.
Before I drop the idea, is a tweeter glued to the pole piece or the horn mouth of a woofer meant for coax as reasonable idea or flawed one? Zaph shows us that some tweets in the $30 range appear much better sonically than cheap compression tweets. If so, then group discounted woofers in the $50-70 range + $30 tweets + XO parts + some machined fittings and/or waveguides + easy assembly and cone mods would seem to make for a bargain high value coax.
I realize this doesn't fit the high 90's sensitivity, but not having heard one, I don't think I'm ready for the big leagues with high $ compression drivers. Otherwise, I like the idea of a group think and experimentation to develop the ideal baffle, because those pursuits will apply to almost any driver.
I realize this doesn't fit the high 90's sensitivity, but not having heard one, I don't think I'm ready for the big leagues with high $ compression drivers. Otherwise, I like the idea of a group think and experimentation to develop the ideal baffle, because those pursuits will apply to almost any driver.
I think it's a reasonable idea. Reasonable as long as the tweeter were efficient. I linked to the morel waveguide model earlier but I'm sure there's better. These compression drivers are 105-110dB, why does it have to be that high for this purpose?
Regarding time alignment: When a compression driver is mounted to the rear of a woofer's magnet, it seems to me that the alignment is pretty out of whack with respect to the woofer's cone (maybe greater than 2-3" in some cases). If the tweeter were set into the cone, it would seem to me that we would be a heck of a lot closer to where we want to be.
edit: At what physical point on a cone is considered the starting point for time alignment? Is it where the VC attaches? The center? Where the surround attaches? Somewhere in the middle? I am curious.
Regarding time alignment: When a compression driver is mounted to the rear of a woofer's magnet, it seems to me that the alignment is pretty out of whack with respect to the woofer's cone (maybe greater than 2-3" in some cases). If the tweeter were set into the cone, it would seem to me that we would be a heck of a lot closer to where we want to be.
edit: At what physical point on a cone is considered the starting point for time alignment? Is it where the VC attaches? The center? Where the surround attaches? Somewhere in the middle? I am curious.
I was thinking this one http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=264-578
I looks like that mounting flange comes right off too. My concern is whether the magnetic field from the woofer could harm the tweeter operation being so close. Then there's also what Lynn mentioned regarding the ribbon and whether those woofer output pressures would affect a dome tweeter.
I looks like that mounting flange comes right off too. My concern is whether the magnetic field from the woofer could harm the tweeter operation being so close. Then there's also what Lynn mentioned regarding the ribbon and whether those woofer output pressures would affect a dome tweeter.
mpmarino said:
I was reading something recently that had me thinking that the origin for a woofer is near the back of the woofer (it does move depending on frequency under consideration) ... the use of a bessel XO to align the origin of the sound for these tweeter behind the woofer configurations is well established.
dave
johninCR said:
John, I think you'll find that the mounting flange sandwiches the replaceable voice coil/diaphram "butterfly" assembly to the magnetic structure; and even with the front plate trimmed down, the diameter remains over 3".
Another interesting style of dome tweeter to consider for coax mounting might be something like the Audax or TB units with small cross section Neo magnets and waveguide / horn loaded mounting plate.
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=276-152
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=264-804
or even,
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=270-011
all of these are sealed back units, with relatively benign cross sections and shapes compared to the Vifa dome.
Ok, what do you think about these ones (I've heard very good things about 8MB400 and 15ND930 when used in home audio aplications; although I don't know nothing about their compresion drivers). I hope they weren't discussed yet.
18Sound 15CX1000
18Sound 12CX800
Although I would remove those "dustcap" covers, especially that grill type on the 12CX800...
18Sound 15CX1000
18Sound 12CX800
Although I would remove those "dustcap" covers, especially that grill type on the 12CX800...
ChrisB,
Yes, those would be easier. I didn't realize any of the really small ones had sufficient efficiency. It must have been a Seas that I saw in the 2.5" range other than the mounting flange.
Is it really possible to tweak a piezo into great sound? I'm willing to give that a go, and it leaves enough room to make the tweeter unit with extra fill on the outside to act as a phase plug for the woofer.
Yes, those would be easier. I didn't realize any of the really small ones had sufficient efficiency. It must have been a Seas that I saw in the 2.5" range other than the mounting flange.
Is it really possible to tweak a piezo into great sound? I'm willing to give that a go, and it leaves enough room to make the tweeter unit with extra fill on the outside to act as a phase plug for the woofer.
For Lynn......
There is a homeopathic medicine ( a plant extract) that promotes fusion of broken bones . It triggers the immune system to speed up the process. I've seen many people use it here with great success. Allopathic doctors do not believe it works , but we have seen it work.
Cheers,
Ashok.
There is a homeopathic medicine ( a plant extract) that promotes fusion of broken bones . It triggers the immune system to speed up the process. I've seen many people use it here with great success. Allopathic doctors do not believe it works , but we have seen it work.
Cheers,
Ashok.
mpmarino said:
Time alignment is less of a problem than it appears. When the tweeter is acoustically in front of the woofer, that's troublesome, since there's no good way to delay treble except in the digital domain. Delaying bass is easy; a multipole Bessel low-pass filter does that, so it's only a matter of juggling the woofer crossover and the desired shape (Butterworth to Bessel family of response shapes).
Anyway, having the tweeter fairly far back is not a problem. What's of more interest is the transition between the tweeter horn to the straight-sided woofer cone, which is a de facto short conical horn. The horrendous tweeter response curves of some of these drivers, with very severe impedance peaks, warns of the danger here. The tweeter curves show FOUR impedance peaks, not finally quieting down until beyond 5 kHz! I think we can agree that's not what we want.
Extremely deep nulls in the tweeter or woofer response is a trouble sign as well, indicating cancellation effects that are not EQ-able in any practical sense. The nulls cause lots of reflections in the time domain as well, as well as nasty sidelobes in the polar pattern. Trouble trouble trouble, avoid avoid avoid. We really don't want to re-design somebody else's driver for them, they should be smart enough to design it right in the first place.
Remember, we want to start with a GOOD driver, not re-design one with lots of problems. If you're going to modify a car, why not start with a Beamer or Mercedes, instead of a Kia?
SunRa said:
WOW! Now that's more like it. Note the HF impedance curve of the 15CX1000, which is very smooth compared to the driver mentioned above. The woofer response of both drivers is still going to need a notch filter: the 15-incher needs a broad notch centered around 1.9 kHz, and the 12-incher needs a fairly narrow one centered around 3 kHz. At a glance, it looks like the 15CX1000 woofer needs a 1st-order rolloff starting around 1.2 to 1.5 kHz, a broad notch filter for the woofer centered at 1.9 to 2.0 kHz, and a 2nd-order highpass for the CD around 2.5 to 3 kHz. The 12CX800 would be a little more difficult, with more complex response shaping - maybe removing the mesh would help.
Looking at the curves, I agree the metal mesh (probably a bug-screen for outdoor use) needs to go - hmm, would 18Sound make an indoor studio-monitor version without it?
I also notice that 18Sound is hip enough to be using oblate spheroid horn profiles in their standalone horns. The bass driver specs are certainly dazzling enough, with lots of distortion-reducing tricks. Hope they sound good - and what is the availability in the USA?
ashok said:
I'm current taking a Traditional Chinese Medicine called "The Great Mender" from Pearl Flower now. Very interested in the homeopath - after all, there shouldn't be any side effects, and homeopaths have a great reputation in Europe. Please inform me of the preferred homeopath in my situation, with tibia and fibula repairing themselves. I live close to Boulder, which has a wide range of alternative-medicine pharmacies.