Originally Posted by tsloms
With the AE and BMS group buys going on currently I've been contemplating a build. I'm good on speakers for my theater so I've been thinking of replacing my mini Ewaves in my living room with some higher quality and louder speakers.
What I have in mind is a build similar to the JTR Noesis in that it would use the BMS 4594 cd on the XR1464 but have a pair of TD10x's instead in the MTM layout. To reduce the number of amp channels I'm thinking of using a passive XO on the CD from high to mid but then actively crossing the CD to the woofers. Perhaps using the Digmoda plate amps (DDC1150 possibly) to reduce separate amps laying around would help clean up the install.
What do you guys think of this layout and setup? Any suggestions or ideas?
Hello Tsloms, I would question the need for mtm. I don't know a lot about it, but it seems to me that this is used to make the box work better around the crossover point, and create lobing, which will decrease the vertical dispersion, and make it so there is always uniform signal from the mids, in comparison to the highs at the crossover point. This is usually implemented with a dome tweeter. The advantage is that as you move away from one mid, you get closer to the other. Also, it is usually at a frequency where the mids are no longer acting as one unit, so separating them is not as big deal a deal. There are trade offs, but some gains.
In your situation you are at a crossover point where the 12s are still working as one unit, IE, within 1/4 wavelength center to center of the cones. I see this as a big factor. I would mount the 12s one on top of the other for better horizontal coverage, and then do the horn on top of those.
Originally Posted by coctostan
I haven't seen the BMS coax's used lower than 500hz and that was with very steep filters.
Hello Coctostan, I use the coaxial compression drivers down to 300hz all the time live. I have also used them live crossed over at 300hz on a horn that was no where near big enough to load that low. This was just to see what would happen. I didn't hear them unload, or flap, and there was no damage.
Originally Posted by mtg90
The 8 vs. 16 ohm does not matter much when going active because you can adjust the gain to match levels. If using a passive crossover the 16 ohm would require less padding to match up with the woofers therefore less power is wasted in the resistors.
I prefer the 16ohm when I use them active. It is easier to match levels. Also, there are unsubstantiated rumors that the 16 ohm sound better.
Originally Posted by A9X-308
I was using my 4590s with Arai radial horns with an Fc at 300Hz. Do a low level FR measurement and they looked good, but they would get very strained in the mids with some level. I never got around to detailed measurements because raising it to 500-600Hz improved it markedly. It stayed there because I had a midbass horn that worked well that high. My hypothesis was that the 4x diaphragm excursion to get the extra octave was taking them out of their linear band.
My concern with an MTM is the C-C spacing of the drivers and how that works out both horizontally and vertically.
My thought is that he will not experience this with the 4594, as much as with the 4590. The 4592, with the neo magnet, has less flux variation throughout the power band. This gives more detailed sound.
Personal preference of course, but I like the mids more from the mid diaphragm than I do from a cone speaker. To me the mid driver has more detail, and better transient response.
Agreed with your MTM/C-C part.
Originally Posted by A9X-308
Based on what I found with the ones that I got when I got my 4590, I'd describe them as crap.
I find the C8-8 and C16-16 quite functional. I have many customers who plan on going active, but get the passives to get started, and then find them so useful that they never go active. Some of the movie houses get one passive, have a tech hook it up, and set up the other channel active, then do a listening test. All of them have ended up going with the passives.
Not sure of your definition of crap is, it is not an esoteric capacitor, but to my mind works great for plug and play.
I did have someone else offer to make me some home rolled crossovers that they had come up with. They had more parts, but did not work as well.
And the guy that I commission to design and build my passives has found no need to improve on their design.
Of course I am all about spending other peoples money, but to my way of thinking, how much time, effort and cost is going to go into just measuring, designing, and building two crossovers?
I have very little experience, and no work flow for this, so it would take me a couple of days.
To me, saving this time, and having it go towards other ends of getting the project off the ground would be worth the money.
And this part of the project could be re-visited at any time down the road. Again the disclaimer that I love to spend other peoples money.
Regards, Jack Arnott
PS, for those not involved in the BMS group buy thread, I am the US distributor, and the one selling the product.Edited by Jack Arnott - 2/24/13 at 11:18pm