Hello everyone,
I am lurking here for several years or more, and using mass of great information available on this forum have build FAST with ScanSpeak 10f fullrange and ScanSpeak 26W woofer a year ago, while I am enjoying this build a lot, it still lacks few things I would like to address with new project.
I am looking for good imaging (controlled directivity) and dynamics in the new speaker. Since listening distance is only 2-2.5m, projects like econowave or similar probably wouldn't work out very well, I really like the "coherence", not sure if this is the right word, of fullrange drivers. Also OB/Dipole designs wouldn't work as speakers must be placed very near to the wall.
So have been thinking more and more about getting pair of BMS 12C362 coaxials. They look very sensitive and does not have ragged HF as most of other coaxials, no idea about off-axis response, but should not be too bad. I want to cross it with subwoofer at 90-100hz and later add helper woofers for the bottom, but this part might take a while.
BMS falls sharply after 400hz, in the spec it says small reflex box achieves F3 at 103HZ, but I don't want reflex box, especially for midrange driver (am I wrong?). Tried simulating with winisd, and it could get to 200hz F3 in about 5-15L sealed box. Is this box not too small? And could it be EQed to 80-100Hz F3 without compromising sound quality, rising distortion too much?
This would be an active system (minidsp).
I am lurking here for several years or more, and using mass of great information available on this forum have build FAST with ScanSpeak 10f fullrange and ScanSpeak 26W woofer a year ago, while I am enjoying this build a lot, it still lacks few things I would like to address with new project.
I am looking for good imaging (controlled directivity) and dynamics in the new speaker. Since listening distance is only 2-2.5m, projects like econowave or similar probably wouldn't work out very well, I really like the "coherence", not sure if this is the right word, of fullrange drivers. Also OB/Dipole designs wouldn't work as speakers must be placed very near to the wall.
So have been thinking more and more about getting pair of BMS 12C362 coaxials. They look very sensitive and does not have ragged HF as most of other coaxials, no idea about off-axis response, but should not be too bad. I want to cross it with subwoofer at 90-100hz and later add helper woofers for the bottom, but this part might take a while.
BMS falls sharply after 400hz, in the spec it says small reflex box achieves F3 at 103HZ, but I don't want reflex box, especially for midrange driver (am I wrong?). Tried simulating with winisd, and it could get to 200hz F3 in about 5-15L sealed box. Is this box not too small? And could it be EQed to 80-100Hz F3 without compromising sound quality, rising distortion too much?
This would be an active system (minidsp).
I tried simulation with WinISD, after LT EQ, excursion looks within limits, even at 40W. Only thing still bothering me is box size, in simulation it is 7L, is it OK or WinISD not calculating this properly? Maybe box size should be increased as it is going to be EQed?
Attachments
Found some off axis measurements, driver is used in commercial german PA monitor "Westlab LABRAT 12". Looks alright, at least in the critical range 1 - 4.5Khz
website(german): Test: Westlab LABRAT 12 - Prosound
website(german): Test: Westlab LABRAT 12 - Prosound
I experimented with some 8" BMS coax (I think 8CN511?) that were about USD 380 each, for an early unity type speaker. BMS makes very good quality speakers,no doubt. However, I think when you are asking the "woofer" to go up into the mids, it limits the very LF potential of the driver. In other words, you will have relatively limited bass with any coax. Since you have simulation tools, and BMS probably publish reliable data, make your own choice. Please share your speaker after you built it.
Well, will try EQ on them firstly, and will add helper woofers eventually. Bought the drivers, hope to get them next week or so, will post some measurements once I have them.
The very best stereo imaging I've ever heard came from coaxials---they can't be beat for this parameter.
Drivers have arrived
Finally have the drivers, took a while, were out of stock, plus some issues with shipping.
Put one of them on a plywood baffle for quick listening, did some basic measurements, used minidsp to add crossover LR24 at 1100hz and shelving filter to compensate for falling HF. It sounds great, as this is my first speaker with compression driver, was afraid of that harshness people often talk about. But no such thing, it sounds very accurate especially with some electronic music, it has sort of "attack/dynamics" if its right word, I don't think my FAST system can compete.
And they can go really loud, was not aware how loud I was listening until I added bass from my FAST speakers, woofer couldn't keep up.
Current plan is to make 20L boxes for coaxials, separate boxes for woofers and cross them at 150hz. Initially was thinking about sealed woofer box, but this way so much efficiency is lost, also can not afford large box at the moment. I looked over number of woofers and currently eyeing Eminence Kappalite 3012LF drivers, they have good sensitivity 95dB and they could be to put in small, about 50-60L vented box, should be able to get 50hz F3 easily (maybe some EQ will be needed).
Finally have the drivers, took a while, were out of stock, plus some issues with shipping.
Put one of them on a plywood baffle for quick listening, did some basic measurements, used minidsp to add crossover LR24 at 1100hz and shelving filter to compensate for falling HF. It sounds great, as this is my first speaker with compression driver, was afraid of that harshness people often talk about. But no such thing, it sounds very accurate especially with some electronic music, it has sort of "attack/dynamics" if its right word, I don't think my FAST system can compete.
And they can go really loud, was not aware how loud I was listening until I added bass from my FAST speakers, woofer couldn't keep up.
Current plan is to make 20L boxes for coaxials, separate boxes for woofers and cross them at 150hz. Initially was thinking about sealed woofer box, but this way so much efficiency is lost, also can not afford large box at the moment. I looked over number of woofers and currently eyeing Eminence Kappalite 3012LF drivers, they have good sensitivity 95dB and they could be to put in small, about 50-60L vented box, should be able to get 50hz F3 easily (maybe some EQ will be needed).
Attachments
This project is on pause, till I have a place where to put big speakers like these, working on the house right now, hope to resume this project in couple of years. Btw, I saw BMS released new coaxial 12C382, these might be even better.
Hi Mindo,
They looks interesting: carbon fiber loaded cones. That said they seems to have a 'bump' at 1k, and drop right after that.
I wonder if this will make the xover design more difficult.
They released a 10" coax too. This is great as they aren't so many interesting units on the market. Same technology used.
They looks interesting: carbon fiber loaded cones. That said they seems to have a 'bump' at 1k, and drop right after that.
I wonder if this will make the xover design more difficult.
They released a 10" coax too. This is great as they aren't so many interesting units on the market. Same technology used.
Well recommended crossovers is at ~ 1.1K (12inch) and 1.2K(10inch), so it should be fine. Also it probably could go lower for home systems.
Still on hold, need to finish new place for these first 🙂 But I hope to start on this in a half year or so.
Is that HF driver a screw-on detachable? Just curious to understand why its a double magnet system.
I am not sure how they are put together, did not try to unscrew it. But HF driver seems to be BMS 4550 which can be bought separately.
Probably done because the most famous coax of all has them 😉: http://www.lansingheritage.org/images/altec/catalogs/1975-home/page13.jpg
I guess a longer throat make more sense than trying to achieve phase alignment where it’s not possible anyway. Interesting for sure. I guess it’s not detachable then but bolted somehow through the LF magnet system and perhaps inside the spider.