Paul,
one question to you since you are in the midst of fixing your tweeters now. How do you actually calculate the profile of an oblate spheroidal waveguide? I am still interested in waveguides, and I looked at the Geddes papers, but from what I read I could not figure out a practical method to actually calculate the profile. Is there any software, or a specific whitepaper? And, will such low compression waveguides work with compression drivers? or rather with dome tweeters?
one question to you since you are in the midst of fixing your tweeters now. How do you actually calculate the profile of an oblate spheroidal waveguide? I am still interested in waveguides, and I looked at the Geddes papers, but from what I read I could not figure out a practical method to actually calculate the profile. Is there any software, or a specific whitepaper? And, will such low compression waveguides work with compression drivers? or rather with dome tweeters?
Member
Joined 2003
MBK,
Those woofers are a work of art! Sorta like a Ferrari speaker 😉
The new version of Hornresp includes the obulate spheroid shape, so you can Google and download that to see the profile. Don't remember who, but someone found a way to take the output of Hornresp (it doesn't give dimensions) and overlay it into one of the MS graphic programs.
The throat is shaped much like the Peavey quadratic, transitioning to a nearly conical flare. Practical implementations use an extremely large roundover to couple the conical section to the baffle plane. The DDS 90 waveguide I'm using is very close to, if not, OS.
The combination of the DDS and BMS 4552ND compression drivers turns out to be a no-brainer...they work extremely well together. They can play huge dynamics and, simultaneously, reproduce a voice 20db down with incredible delicacy. Really quite astounding.
As you know from Jussi's thread, several people seem to be learning that combining WGs with soft domes isn't as simple as it seems. I was surprised to find the Seas 27TDFC didn't work well in the waveguide pictured earlier...but an old Vifa 27TG35-06 worked like a champ. Seems the dome/throat interface is extremely critical. More work to do!
Paul
Those woofers are a work of art! Sorta like a Ferrari speaker 😉
The new version of Hornresp includes the obulate spheroid shape, so you can Google and download that to see the profile. Don't remember who, but someone found a way to take the output of Hornresp (it doesn't give dimensions) and overlay it into one of the MS graphic programs.
The throat is shaped much like the Peavey quadratic, transitioning to a nearly conical flare. Practical implementations use an extremely large roundover to couple the conical section to the baffle plane. The DDS 90 waveguide I'm using is very close to, if not, OS.
The combination of the DDS and BMS 4552ND compression drivers turns out to be a no-brainer...they work extremely well together. They can play huge dynamics and, simultaneously, reproduce a voice 20db down with incredible delicacy. Really quite astounding.
As you know from Jussi's thread, several people seem to be learning that combining WGs with soft domes isn't as simple as it seems. I was surprised to find the Seas 27TDFC didn't work well in the waveguide pictured earlier...but an old Vifa 27TG35-06 worked like a champ. Seems the dome/throat interface is extremely critical. More work to do!
Paul
Paul,
thanks for the links, I got Hornresp and it looks quite straightforward. Great to hear that your horns work out well. If I understand correctly, there is no front chamber? How does the dispersion look like (both in subjective room balance, and in off axis response data re: mating with the dipole mid?) Theoretically a ca. 100-120 degrees waveguide should fit a dipole, and most commerical WG's are at best 90 degrees square. But well, the proof is always in the pudding.
If it wasn't for the hole in my pocket after the 18Sound purchase I'd walk, no, run out the door and try a pro compression driver now. I'm not too keen on trying to "fix" a regular dome tweeter... It's not imminent but I like to think ahead, and I have some gaps to make up for, I have been building dipoles for about 6, 7 years but I am completely naive wrt horns. If I was able to design something correctly, the rest would be fairly easy - I am one of *those* people with a friend who has a CNC machine...
thanks for the links, I got Hornresp and it looks quite straightforward. Great to hear that your horns work out well. If I understand correctly, there is no front chamber? How does the dispersion look like (both in subjective room balance, and in off axis response data re: mating with the dipole mid?) Theoretically a ca. 100-120 degrees waveguide should fit a dipole, and most commerical WG's are at best 90 degrees square. But well, the proof is always in the pudding.
If it wasn't for the hole in my pocket after the 18Sound purchase I'd walk, no, run out the door and try a pro compression driver now. I'm not too keen on trying to "fix" a regular dome tweeter... It's not imminent but I like to think ahead, and I have some gaps to make up for, I have been building dipoles for about 6, 7 years but I am completely naive wrt horns. If I was able to design something correctly, the rest would be fairly easy - I am one of *those* people with a friend who has a CNC machine...
Member
Joined 2003
Yes, there is no front chamber.
I've just started to look at off-axis response. No turntable yet, so nothing to report with much accuracy.
I targeted a 1.1k crossover to coincide with a dip in hearing sensitivity. However, in-room RTA measurements showed there was tweeter flare near crossover...in other words the DDS WG began losing pattern control in the crossover region. (The mids have felt damping on the backwave, so they don't act like dipoles at XO.) Raising the crossover to 1.5k reduced the flare at XO and cured a slightly "forward" sound resulting from the flare.
Here are some MLS measurements of the 4552 in two different waveguides. (raw driver and WG, no EQ of any sort)
The 4552 at the mouth of the WG (short range to look more closely at the driver/WG, deemphasizing the baffle).
4552 measured at the mouth of a slightly modified version of the inexpensive WGs pictured earlier in this thread:
4552 and DDS WG at 500mm on-axis and about 45 degrees off-axis:
4552 and inexpensive WG at 500mm on-axis and about 45 degrees off-axis:
The modified WG holds pattern control lower so it shows good potential for my 1.1k goal. Unfortunately, it fits the baffles with Seas drivers, not the 18sound mids!
I'll get a turntable put together in a week or two to improve off-axis measurement accuracy, but I sure wish I had access to your friends CNC machine! I see MDF dust in my future
I've just started to look at off-axis response. No turntable yet, so nothing to report with much accuracy.
I targeted a 1.1k crossover to coincide with a dip in hearing sensitivity. However, in-room RTA measurements showed there was tweeter flare near crossover...in other words the DDS WG began losing pattern control in the crossover region. (The mids have felt damping on the backwave, so they don't act like dipoles at XO.) Raising the crossover to 1.5k reduced the flare at XO and cured a slightly "forward" sound resulting from the flare.
Here are some MLS measurements of the 4552 in two different waveguides. (raw driver and WG, no EQ of any sort)
The 4552 at the mouth of the WG (short range to look more closely at the driver/WG, deemphasizing the baffle).
An externally hosted image should be here but it was not working when we last tested it.
4552 measured at the mouth of a slightly modified version of the inexpensive WGs pictured earlier in this thread:
An externally hosted image should be here but it was not working when we last tested it.
4552 and DDS WG at 500mm on-axis and about 45 degrees off-axis:
An externally hosted image should be here but it was not working when we last tested it.
4552 and inexpensive WG at 500mm on-axis and about 45 degrees off-axis:
An externally hosted image should be here but it was not working when we last tested it.
The modified WG holds pattern control lower so it shows good potential for my 1.1k goal. Unfortunately, it fits the baffles with Seas drivers, not the 18sound mids!
I'll get a turntable put together in a week or two to improve off-axis measurement accuracy, but I sure wish I had access to your friends CNC machine! I see MDF dust in my future
Hmm, I suppose some pictures were supposed to be showing up in your post 
- I can't find link text!
So these compression drivers are OK with fairly shallow flare rates and no extra front chambers, that's good to know.
I've done some rough estimates with hornresp and some thinking, and it looks like to get the X-O down to 1.2k or less, which is desirable / mandatory for directivity matching, but also for staying within acceptable driver spacing at XO wavelength, you / I are somehow in a bind. Either you have stronger directivity than desired, say 60-80 degrees (and a dipole would warrant about 120 degrees but let's say we can get away with 90), or you go for a shallower angle but then the thing becomes both deeper and wider at the mouth than desirable. Deeper may not be an issue depending on existing baffle dimensions (me I am looking for total depth with driver below 7.5") but mouth diameter will increasingly nullify low XO point advantage of driver spacing because it will drive the drivers apart again...
Maybe there is an optimum point somewhere. Geddes in his Summa, after all, does manage to cross a monopole to a OS WG at 900 Hz, to a 15" no less, so there must be a way. But then again Geddes targets both a fairly high directivity of the tweeter horn, and recommends off-axis listening. This all I would actually want to avoid - just keep it close to dipole pattern til 60 degrees. Or else sitting outside the sweet spot may not be pleasant...
Anyway I also looked at 18Sound horns online. They only have three, but quite sophisticated ones, and could fit for this application. Though they don't say the word, the description sounds like what an OS WG intends to achieve, constant directivity without reflections; they have 60x40, 80x40 and 90x60, the latter is model XT120). They all lose control progressively below 1.5K but from eyeballing the curves, should just about reach dipole pattern at 1.2K. For your likely cardioid pattern you should be fine at around 1k then. Maybe no sawdust after all...
Turntable: ha! I made mine a moth ago from an old laminated table top that neighbors left on the curb for trash. Just put a bolt, a drawer handle for operating it, and greased the interface...
BTW another question: how is the imaging with these WGs? Not that I'd make a fetsih out of pinpoint imaging - I often find it distracting given the idiosyncrasies of many CD's mastering - but a little bit of it sure is nice...
Edit: now I suddenly see the pix. Odd. These measurements look very promising already. The directivity holds really well. Now the question is fitting the dimensions I suppose...
- I can't find link text!So these compression drivers are OK with fairly shallow flare rates and no extra front chambers, that's good to know.
I've done some rough estimates with hornresp and some thinking, and it looks like to get the X-O down to 1.2k or less, which is desirable / mandatory for directivity matching, but also for staying within acceptable driver spacing at XO wavelength, you / I are somehow in a bind. Either you have stronger directivity than desired, say 60-80 degrees (and a dipole would warrant about 120 degrees but let's say we can get away with 90), or you go for a shallower angle but then the thing becomes both deeper and wider at the mouth than desirable. Deeper may not be an issue depending on existing baffle dimensions (me I am looking for total depth with driver below 7.5") but mouth diameter will increasingly nullify low XO point advantage of driver spacing because it will drive the drivers apart again...
Maybe there is an optimum point somewhere. Geddes in his Summa, after all, does manage to cross a monopole to a OS WG at 900 Hz, to a 15" no less, so there must be a way. But then again Geddes targets both a fairly high directivity of the tweeter horn, and recommends off-axis listening. This all I would actually want to avoid - just keep it close to dipole pattern til 60 degrees. Or else sitting outside the sweet spot may not be pleasant...
Anyway I also looked at 18Sound horns online. They only have three, but quite sophisticated ones, and could fit for this application. Though they don't say the word, the description sounds like what an OS WG intends to achieve, constant directivity without reflections; they have 60x40, 80x40 and 90x60, the latter is model XT120). They all lose control progressively below 1.5K but from eyeballing the curves, should just about reach dipole pattern at 1.2K. For your likely cardioid pattern you should be fine at around 1k then. Maybe no sawdust after all...
Turntable: ha! I made mine a moth ago from an old laminated table top that neighbors left on the curb for trash. Just put a bolt, a drawer handle for operating it, and greased the interface...
BTW another question: how is the imaging with these WGs? Not that I'd make a fetsih out of pinpoint imaging - I often find it distracting given the idiosyncrasies of many CD's mastering - but a little bit of it sure is nice...
Edit: now I suddenly see the pix. Odd. These measurements look very promising already. The directivity holds really well. Now the question is fitting the dimensions I suppose...
Member
Joined 2003
You're right, the challenge is balancing directivity, driver spacing, driver response, etc. It is especially difficult considering the huge mouth roundover included in the really successful waveguide designs. Just estimating, but about half the DDS diameter is dedicated to the roundover at the mouth! If that roundover weren't necessary, the WG could hold pattern control much lower by extending the ~conical section further toward the mouth...or the size could be used for a broader pattern...or a compromise between the two. Everything is a compromise!
Compared to the ribbons (which image like crazy) WG imaging seems "okay"...everything is appropriately sized, stage width and depth fairly good, center stage is very good. With the controlled radiation pattern, the WGs may image better than the ribbons in a smaller room...in this case speaker location is several feet from the nearest wall so early reflections are low for both systems. Haven't worked on the midrange radiation pattern yet (just guessing with the felt) so imaging may improve further.
Sorry about the pics...guess I should have used a smaller file size.
Compared to the ribbons (which image like crazy) WG imaging seems "okay"...everything is appropriately sized, stage width and depth fairly good, center stage is very good. With the controlled radiation pattern, the WGs may image better than the ribbons in a smaller room...in this case speaker location is several feet from the nearest wall so early reflections are low for both systems. Haven't worked on the midrange radiation pattern yet (just guessing with the felt) so imaging may improve further.
Sorry about the pics...guess I should have used a smaller file size.
That's good to hear. The change from wide dispersion ribbons to 90 degree coverage horns must be quite a drastic one - at least assuming that the "air" from ribbons, as it is said, comes from the wide dispersion. That's a bit my fear re: trying horns, that some airiness and imaging might get lost as compared even to a standard dome tweeter.
OTOH when I think of the effect this 15" has on my system - one might think that increased cone flex, energy storage, moving mass, all this in theory should make it less optimal than a good smaller diameter HiFi midrange. But no - it is all more than made up by the effortlessness and the now truly realistic dynamics, and the gain in detail that comes with it. With the 8" down to 100 Hz it was very clean, but SPL-wise it was "not loud enough - still not loud enough - distorted" ...
Your first impressions indicate that something similar happens at the HF end when using the "pro" approach. Curious to see your progress in the implementation!
OTOH when I think of the effect this 15" has on my system - one might think that increased cone flex, energy storage, moving mass, all this in theory should make it less optimal than a good smaller diameter HiFi midrange. But no - it is all more than made up by the effortlessness and the now truly realistic dynamics, and the gain in detail that comes with it. With the 8" down to 100 Hz it was very clean, but SPL-wise it was "not loud enough - still not loud enough - distorted" ...
Your first impressions indicate that something similar happens at the HF end when using the "pro" approach. Curious to see your progress in the implementation!
Member
Joined 2003
Yes, SL's 2nd tweeter has created quite a stir 😉 . It is probably the right thing to do when there is a large distance to the front wall. Too close to the wall and imaging goes away.
For now, I'll stick with my plan to damp the backwave of the mid with a heavy layer of wool felt to attenuate the top end...in other words, balance the radiation pattern at XO without a rear tweeter.
Of course I am reminded of something a very wise boss once told me: "Never say never because never is such a very, very long time!"
For now, I'll stick with my plan to damp the backwave of the mid with a heavy layer of wool felt to attenuate the top end...in other words, balance the radiation pattern at XO without a rear tweeter.
Of course I am reminded of something a very wise boss once told me: "Never say never because never is such a very, very long time!"
Just saw that I am sooo late. All old news, with entire threads on it etc.
Anyway I am smiling somehow. I do respect Linkwitz a lot. I came upon his site in ca 1999 or so, when he just had his Phoenix there. I knew nothing about speakers except that I didn't like my commerical ones anymore. I learned so much from him, and he's done an immense service to DIY and I think even to industry. His materials are ueber-complete, free online, and honest to the bone, specifically so in their occasional reversals of opinion. He presents discussions of issues that no one else does in this form. He presents measurements and theory galore. He fine unes with real life experience. A lot of the talk about dispersion and power response, let alone all modern dipole building , other manufacturers etc, somehow was built on his advocacy.
Yet I see two ironies: one is that at this point of quality changes such as these have probably as many cons as pros. In other words we get into diminishing returns, or taste dependency, or at worst, hairsplitting. In other words, rear tweeter or not, both will work to some extent.
The other irony is that I always went my own ways - I never built any SL model. I first built a 10"-6"fullrange-10" MTM dipole, and then modified it again and again until I came to my wide body shallow U frame with top edge-mounted tweeter (specifically so that some radiation would come over to the back - measurements surprised me as to how much actually does). So I don't fall into the "apostle" category that tends to be disappointed when the master has a slight change of opinion. Still, as an amateur DIYer, I suppose now with "medium-to-advanced" experience, I still always suspect that the pros might know something on top of me. And often they do. But sometimes my instincts and best guesses are probably just as good, and so are the approaches of a lot of other experienced builders. Hey maybe SL one day will come out and recommend pro drivers of massive diameters, such as advocated in this thread, for detail and dynamics ;-))
Anyway Paul I like your approach with the felt. I had been thinking about that for a while but had too much fun / "work" fiddling with other aspects of the design and didn't have a specific resonance problem that made it mandatory. The thing is, I do agree with SL and all of us here I guess, that radiation patterns matter, and the better they are matched, the merrier. So given that a top end dipole is always problematic (especially when front wall close) and that a front tweeter, loaded or not, can not match a dipole perfectly, I tend towards trying cardioid next, if I only knew a good way to build one. That would allow to do what you are doing, adding a pro horn for the top end and have both matching radiation patterns within reasonable reach, and the dynamics and power response of good pro drivers.
Trouble with cardioid is, the damping approaches seem very try and error heavy, and the delayed bipole woofer approach has even more complexity than dipole bass, never mind cost.
What is your experience with felt? Does the benefit exceed sheer damping - are the radiation patterns achieved desirable, constant with frequency, and smooth / predictable? FWIW SL himself on some page mentions feltmetal (sintered metal felt) with defined resistances to air (used in soundproofing to cancel 1/4 wave resonances in jet exhausts etc) as a candidate. Is that worth the trouble of procuring it, or is natural wool felt just as useable / consistent / predictable?
Anyway I am smiling somehow. I do respect Linkwitz a lot. I came upon his site in ca 1999 or so, when he just had his Phoenix there. I knew nothing about speakers except that I didn't like my commerical ones anymore. I learned so much from him, and he's done an immense service to DIY and I think even to industry. His materials are ueber-complete, free online, and honest to the bone, specifically so in their occasional reversals of opinion. He presents discussions of issues that no one else does in this form. He presents measurements and theory galore. He fine unes with real life experience. A lot of the talk about dispersion and power response, let alone all modern dipole building , other manufacturers etc, somehow was built on his advocacy.
Yet I see two ironies: one is that at this point of quality changes such as these have probably as many cons as pros. In other words we get into diminishing returns, or taste dependency, or at worst, hairsplitting. In other words, rear tweeter or not, both will work to some extent.
The other irony is that I always went my own ways - I never built any SL model. I first built a 10"-6"fullrange-10" MTM dipole, and then modified it again and again until I came to my wide body shallow U frame with top edge-mounted tweeter (specifically so that some radiation would come over to the back - measurements surprised me as to how much actually does). So I don't fall into the "apostle" category that tends to be disappointed when the master has a slight change of opinion. Still, as an amateur DIYer, I suppose now with "medium-to-advanced" experience, I still always suspect that the pros might know something on top of me. And often they do. But sometimes my instincts and best guesses are probably just as good, and so are the approaches of a lot of other experienced builders. Hey maybe SL one day will come out and recommend pro drivers of massive diameters, such as advocated in this thread, for detail and dynamics ;-))
Anyway Paul I like your approach with the felt. I had been thinking about that for a while but had too much fun / "work" fiddling with other aspects of the design and didn't have a specific resonance problem that made it mandatory. The thing is, I do agree with SL and all of us here I guess, that radiation patterns matter, and the better they are matched, the merrier. So given that a top end dipole is always problematic (especially when front wall close) and that a front tweeter, loaded or not, can not match a dipole perfectly, I tend towards trying cardioid next, if I only knew a good way to build one. That would allow to do what you are doing, adding a pro horn for the top end and have both matching radiation patterns within reasonable reach, and the dynamics and power response of good pro drivers.
Trouble with cardioid is, the damping approaches seem very try and error heavy, and the delayed bipole woofer approach has even more complexity than dipole bass, never mind cost.
What is your experience with felt? Does the benefit exceed sheer damping - are the radiation patterns achieved desirable, constant with frequency, and smooth / predictable? FWIW SL himself on some page mentions feltmetal (sintered metal felt) with defined resistances to air (used in soundproofing to cancel 1/4 wave resonances in jet exhausts etc) as a candidate. Is that worth the trouble of procuring it, or is natural wool felt just as useable / consistent / predictable?
Member
Joined 2003
Yup, we all benefit from the work SL has done, and continues to do. I've spent countless hours on his page and every time I visit, something has been added or updated. Just last week I ordered his test CDs to "listen to my room"...he sent me a note the following day saying the CDs had already shipped. Very good attention for a very small order!
Based on SL's web page, I once tried to source feltmetal but gave up because it wasn't clear what porosity to buy and it was too bloody expensive to be wrong! The wool felt I'm using does not attenuate all frequencies equally...it acts more like a low-pass filter with higher frequencies attenuated more than LF. While it isn't as elegant as feltmetal, it works for rolling off the top end, which is what I want to accomplish. BTW, I've found real wool works far better than synthetics, perhaps because of the "scale" structure of the individual fibers.
Wool felt is available in many different densities and thicknesses from McMaster.com. It is easy to experiment with...you can simply fold or cut up an old wool blanket to try different thicknesses. Of course I don't know how many wool blankets you need in Singapore!
Based on SL's web page, I once tried to source feltmetal but gave up because it wasn't clear what porosity to buy and it was too bloody expensive to be wrong! The wool felt I'm using does not attenuate all frequencies equally...it acts more like a low-pass filter with higher frequencies attenuated more than LF. While it isn't as elegant as feltmetal, it works for rolling off the top end, which is what I want to accomplish. BTW, I've found real wool works far better than synthetics, perhaps because of the "scale" structure of the individual fibers.
Wool felt is available in many different densities and thicknesses from McMaster.com. It is easy to experiment with...you can simply fold or cut up an old wool blanket to try different thicknesses. Of course I don't know how many wool blankets you need in Singapore!
Hi guys.
I have a big midrange OB project going. The mid is really big -18"! OK, it's a horn. Altec 811 with 806 driver.
Just going to be a 2 way to start. Bottom end is the Selenium 15PW3. A mid Q pro woofer. Should be great for OB. It has a very nice tone and pretty good midrange played fullrange. Nothing as fancy or lovely as your 18 Sound beauties, but a nice driver none the less.
Crossover and shelving filters will be active, at least in the begining.
Can't work on them today - rain. Should be up and running in a few days, rain willing.
I have a big midrange OB project going. The mid is really big -18"! OK, it's a horn. Altec 811 with 806 driver.
Just going to be a 2 way to start. Bottom end is the Selenium 15PW3. A mid Q pro woofer. Should be great for OB. It has a very nice tone and pretty good midrange played fullrange. Nothing as fancy or lovely as your 18 Sound beauties, but a nice driver none the less.
Crossover and shelving filters will be active, at least in the begining.
Can't work on them today - rain. Should be up and running in a few days, rain willing.
Anxious to hear more about your experiences here, any updates from those of you experimenting with 18sound drivers large and small (well smaller I guess, as a 10" mid is still a large mid cone driver in relative terms...).
I am personally thinking about a three way active:
BMS 45552 with DDS Eng 90 for the top end (roughly 1400hz and up...)
Eighteensound 10NDA520 for the mid (maybe 200-1400hz)
TBD Pro Sound driver running in open box dipole of some sort (40-200hz) with a single sub handling the combined L/R from 40hz on down.
I am looking for more feedback on the 10NDA520 before I pull the trigger, and I am also wondering if those of you experimenting thus far have an opinion on digital versus analog active crossover. I am tempted to just bite the bullet and go digital, with a DEQX or PC based solution, but I am also a vinyl nut and thinking about tube amps, and considering Marchand line level passive components built into a preamp or each power amp. The big issue I think is the time alignment that digital offers but maybe there are other things to consider as well. Of course the flexibility of the digital stuff is unsurpassed, but the idea of a pure analog system is alluring to me as well. Any thoughts? Is it tough to get a good phase relationship between the mid cone and the waveguide or do their acoustic centers appear to be close enough for decent analog crossover work?
And finally, for those of you running 12s and 15s open baffle, if you could have any pro driver in the world for the job, running it 40-200Hz (maybe even with a little eq around 40-60hz to help out), what would you pick?
Thanks,
Greg Jensen
I am personally thinking about a three way active:
BMS 45552 with DDS Eng 90 for the top end (roughly 1400hz and up...)
Eighteensound 10NDA520 for the mid (maybe 200-1400hz)
TBD Pro Sound driver running in open box dipole of some sort (40-200hz) with a single sub handling the combined L/R from 40hz on down.
I am looking for more feedback on the 10NDA520 before I pull the trigger, and I am also wondering if those of you experimenting thus far have an opinion on digital versus analog active crossover. I am tempted to just bite the bullet and go digital, with a DEQX or PC based solution, but I am also a vinyl nut and thinking about tube amps, and considering Marchand line level passive components built into a preamp or each power amp. The big issue I think is the time alignment that digital offers but maybe there are other things to consider as well. Of course the flexibility of the digital stuff is unsurpassed, but the idea of a pure analog system is alluring to me as well. Any thoughts? Is it tough to get a good phase relationship between the mid cone and the waveguide or do their acoustic centers appear to be close enough for decent analog crossover work?
And finally, for those of you running 12s and 15s open baffle, if you could have any pro driver in the world for the job, running it 40-200Hz (maybe even with a little eq around 40-60hz to help out), what would you pick?
Thanks,
Greg Jensen
Member
Joined 2003
panomaniac,
Please post a picture or two when you have the system together! As a youngster, my very first exposure to good sound was a big Altec system in one of the grand old theaters in Chicago. My dad later said that's all I talked about for two weeks!
Greg,
It seems like you are headed almost exactly the same from 200Hz up. I first tried the 4552/DDS at 1,100, but the WG doesn't seem to hold pattern control low enough...so XO is 1,500 at the moment. Low XO is at 175-200.
So far, my only "complaint" about the 520 is that the basket assembly (probably reused from a ceramic driver) casts a fairly large shadow over the back of the cone. When I'm done experimenting with waveguides, I'll move on to the mid as it appears it might benefit from some felt strips or some other treatment on the frame around the spider. Response is fairly smooth as-is...EQ is primarily for the baffle, not the driver. I did a very quick HD check with and without the AIC and found about a 10db distortion improvement with the AIC...didn't expect anything nearly that good.
For crossover, I still have a warm spot for analog, but digital seems much more practical, especially when it comes to EQ. EQing the mid is no big deal, but the compression driver/WG/baffle is a different animal...in one spot, the DCX takes out a 1.5db bump with a Q of about 8 which would be tricky with analog.
With the mid mounted to the rear of a 3/4" baffle, WG to the front, there is almost no acoustic offset between the mid and tweeter. DCX time offset is almost nil. Of course there is a several inch offset to the woofer.
Don't know which 12-15" woofers would be best (why 12?) but I'd start the search with BMS and 18sound.
Please post a picture or two when you have the system together! As a youngster, my very first exposure to good sound was a big Altec system in one of the grand old theaters in Chicago. My dad later said that's all I talked about for two weeks!
Greg,
It seems like you are headed almost exactly the same from 200Hz up. I first tried the 4552/DDS at 1,100, but the WG doesn't seem to hold pattern control low enough...so XO is 1,500 at the moment. Low XO is at 175-200.
So far, my only "complaint" about the 520 is that the basket assembly (probably reused from a ceramic driver) casts a fairly large shadow over the back of the cone. When I'm done experimenting with waveguides, I'll move on to the mid as it appears it might benefit from some felt strips or some other treatment on the frame around the spider. Response is fairly smooth as-is...EQ is primarily for the baffle, not the driver. I did a very quick HD check with and without the AIC and found about a 10db distortion improvement with the AIC...didn't expect anything nearly that good.
For crossover, I still have a warm spot for analog, but digital seems much more practical, especially when it comes to EQ. EQing the mid is no big deal, but the compression driver/WG/baffle is a different animal...in one spot, the DCX takes out a 1.5db bump with a Q of about 8 which would be tricky with analog.
With the mid mounted to the rear of a 3/4" baffle, WG to the front, there is almost no acoustic offset between the mid and tweeter. DCX time offset is almost nil. Of course there is a several inch offset to the woofer.
Don't know which 12-15" woofers would be best (why 12?) but I'd start the search with BMS and 18sound.
Greg,
can only comment about the woofers. Here I got pretty much what I wanted: neo motor PLUS demodulation rings, medium mass cone and very open spider. Of course the 12" with AIC seem nice too as of Paul's measurements - it seems there is a point to it.
I don't know all possible alternatives of course - I checked just a few usual suspect brands, being new to pro sound brands I sure left some important ones out, and I focused on availability (to me, in Singapore). B&C's TBX series are nice as well, but not neo, and their neos don't have demodulation rings, and seem hard to get. But honest, I believe a lot of pro drivers in the upper price brackets (... well, you get what you pay for) will be great I reckon.
Paul: I did notice that some 18Sound drivers have a rather massive basket, all their ferrite drivers have those and some of their neos as well - I chose the 15ND930 over the 9300 because of the open basket, feature wise I forgo the double spider and 1 mm or so of xmax vs. the 9300.
Felt: curiously there is a feltmetal manufacturer's rep office in Singapore. I think anything that can be traded, will be traded, in Singapore. One of the strong points here. (Weakness #1: not all that glitters is gold, and certainly not the #$%!!-plated terminals they're selling en masse in the many electronics shops here. no matter what brand is printed on them). But I didn't dare calling, picturing the conversation "So, how many tonnes do you want?" - "Ahem, samples?" "What's your production run?" "Welllll..." etc. So I may try natural felt on the woofers at first. Off axis only the deep bass falls off noticeably in my system, all else remains balanced, so I may only have to dampen the woofer rear to eq the power resppnse.
can only comment about the woofers. Here I got pretty much what I wanted: neo motor PLUS demodulation rings, medium mass cone and very open spider. Of course the 12" with AIC seem nice too as of Paul's measurements - it seems there is a point to it.
I don't know all possible alternatives of course - I checked just a few usual suspect brands, being new to pro sound brands I sure left some important ones out, and I focused on availability (to me, in Singapore). B&C's TBX series are nice as well, but not neo, and their neos don't have demodulation rings, and seem hard to get. But honest, I believe a lot of pro drivers in the upper price brackets (... well, you get what you pay for) will be great I reckon.
Paul: I did notice that some 18Sound drivers have a rather massive basket, all their ferrite drivers have those and some of their neos as well - I chose the 15ND930 over the 9300 because of the open basket, feature wise I forgo the double spider and 1 mm or so of xmax vs. the 9300.
Felt: curiously there is a feltmetal manufacturer's rep office in Singapore. I think anything that can be traded, will be traded, in Singapore. One of the strong points here. (Weakness #1: not all that glitters is gold, and certainly not the #$%!!-plated terminals they're selling en masse in the many electronics shops here. no matter what brand is printed on them). But I didn't dare calling, picturing the conversation "So, how many tonnes do you want?" - "Ahem, samples?" "What's your production run?" "Welllll..." etc. So I may try natural felt on the woofers at first. Off axis only the deep bass falls off noticeably in my system, all else remains balanced, so I may only have to dampen the woofer rear to eq the power resppnse.
Paul,
Thanks for the response. Yeah, I have been gaining in courage to go the waveguide route after hearing the Audio Kinesis and Emerald Physics efforts at RMAF back in October. In the case of Emerald Physics, I could see that the waveguide wasn't really all that deep and if I mounted the mid on the back side of the baffle I might get away with it.
The idea of running my turntable - phone pre into an AD device and then into a DEQX or computer based solution is probably going to be something I will have to get used to as my resistance lowers with each passing day... with the digital products getting better and my understanding of just how much skill I lack to design a good analog crossover, it will probably be a no-brainer for me very soon.
I mentioned 12s just in case I was tempted to double them up, ideally, I am really thinking about a 15 inch woofer in a an open back box with a matching box frame with front baffle only sitting on top to house the mid/waveguide-tweet. Thinking seriously about the Ciare driver with decent excursion but not sure if it would work well open baffle due to TS params and basket/spider design (but I am just blabbin here, no real tech expertise to back it up, just nerves about wasting money and not being happy with end result...)
I do feel pretty good about my general guidelines for this project however, just need to learn a little more, save a little more dough, and then give it a whirl. I am working on a Pi speaker kit right now, so it will be interesting to see how my wife and I react to the "pro sound" approach to hifi in the home.
Thanks for the response. Yeah, I have been gaining in courage to go the waveguide route after hearing the Audio Kinesis and Emerald Physics efforts at RMAF back in October. In the case of Emerald Physics, I could see that the waveguide wasn't really all that deep and if I mounted the mid on the back side of the baffle I might get away with it.
The idea of running my turntable - phone pre into an AD device and then into a DEQX or computer based solution is probably going to be something I will have to get used to as my resistance lowers with each passing day... with the digital products getting better and my understanding of just how much skill I lack to design a good analog crossover, it will probably be a no-brainer for me very soon.
I mentioned 12s just in case I was tempted to double them up, ideally, I am really thinking about a 15 inch woofer in a an open back box with a matching box frame with front baffle only sitting on top to house the mid/waveguide-tweet. Thinking seriously about the Ciare driver with decent excursion but not sure if it would work well open baffle due to TS params and basket/spider design (but I am just blabbin here, no real tech expertise to back it up, just nerves about wasting money and not being happy with end result...)
I do feel pretty good about my general guidelines for this project however, just need to learn a little more, save a little more dough, and then give it a whirl. I am working on a Pi speaker kit right now, so it will be interesting to see how my wife and I react to the "pro sound" approach to hifi in the home.
Thanks MBK! I do like how they look. The "lizard skin" stretched around the woofer opening came out particularly well.
Still need to paint the backs and foot plates - and the horns, they are a bit dinged up on the edges. Wings will come later. BTW, they look absolutely huge in my small living room.
I will post more details later, maybe in a separate thread.
Still need to paint the backs and foot plates - and the horns, they are a bit dinged up on the edges. Wings will come later. BTW, they look absolutely huge in my small living room.
I will post more details later, maybe in a separate thread.
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