I'd like to build MTM center channel speaker with my existing 2x SB17NRX, cross low enough maybe around 350Hz to avoid issues with horizontal dispersion. so the option will be using 5" or 6" coaxial driver
candidates so far :
in my short research, it seems using pro driver coaxial have benefit to provide more headroom instead of SB coaxial. i exclude using fullrange driver (i have 1 pair of alpair 10p unused) or maybe other 5" / 6" like fostex or lii audio which has lower headroom
any input will be appreciated, because i rarely find center speaker project with coaxial, majority using midrange + tweeter combination, where low height box is also my consideration. 20cm height is the maximum that i will use because it will be placed under TV
thanks
candidates so far :
- sb16pfc25-4-coax
- celestion tfx0512
- faital pro 6hx150
in my short research, it seems using pro driver coaxial have benefit to provide more headroom instead of SB coaxial. i exclude using fullrange driver (i have 1 pair of alpair 10p unused) or maybe other 5" / 6" like fostex or lii audio which has lower headroom
any input will be appreciated, because i rarely find center speaker project with coaxial, majority using midrange + tweeter combination, where low height box is also my consideration. 20cm height is the maximum that i will use because it will be placed under TV
thanks
Hi gadut,
take a look at:
http://www.audioexcite.com/?page_id=3807
and
http://www.audioexcite.com/?page_id=3614
Sincerely
take a look at:
http://www.audioexcite.com/?page_id=3807
and
http://www.audioexcite.com/?page_id=3614
Sincerely
My two cents: If you trim the flanges and slightly offset a tweeter ( small form factors easier) you can do an MTM with a bit better control over lobe issues in a box no taller than the woofers. I wound up doing a strait MTM because I used the DXT tweeter, but for the pretty narrow listening position we sit in, we have no issues. If you need to sit all over the room, wide couch, multiple rows etc, yea, then MTM can be an issue.
I have listened to several coaxial speakers recently and for some reason, they are super sensitive to your location. Move your head a foot and the image jumps across the room. LS-50's are a prime example. I also think the available coax drivers are not quite up to par with standard ones. I'll take the SB or Seas for affordable, CSS and Purify if money to burn. It could be the crossovers as implemented, or the additional issues you get with a moving waveguide tweeter. It would be fun to play with one using host based crossovers so you can deal with the phase more carefully than in a passive system.
I have listened to several coaxial speakers recently and for some reason, they are super sensitive to your location. Move your head a foot and the image jumps across the room. LS-50's are a prime example. I also think the available coax drivers are not quite up to par with standard ones. I'll take the SB or Seas for affordable, CSS and Purify if money to burn. It could be the crossovers as implemented, or the additional issues you get with a moving waveguide tweeter. It would be fun to play with one using host based crossovers so you can deal with the phase more carefully than in a passive system.
Well, that is what I hear. Not what I expected but what I heard. One pair was the LS50, I never heard of the other ones and as I dismissed them, don't remember. I thought the Kef's would be great desk or console near-field monitors.
Too big for under my TV, but I would like to hear the bigger Seas.
Too big for under my TV, but I would like to hear the bigger Seas.
It's often difficult to get a coax crossover low enough to avoid weird transitions in the radiation pattern.
A smaller woofer or horn/waveguide tweeter are useful here, unless we're talking nearfield/desktop spl.
A monster like a bug Tannoy can have a pretty big tweeter, even without a horn.
But that's a big box.
A smaller woofer or horn/waveguide tweeter are useful here, unless we're talking nearfield/desktop spl.
A monster like a bug Tannoy can have a pretty big tweeter, even without a horn.
But that's a big box.
Thanks for all your input, regarding other coaxial like Kartesian or KEF, it's not available locally and i avoid to import them. too much extra cost involved. and using tweeter only with NRX will create lobbing issues that i will like to avoid
i will build separate boxes for each NRX so i can replace coaxial or fullrange by it's own box. my first start I'll use alpair 10p and SB16 coax, let's see how loud it can get.
btw i don't have any AVR yet, still long way to buy it because there still several audio project waiting. i really need to raise tv position because i want to put my tube dac on top of my rack (black chassis on lower rack which collect heat alot) which block tv view
i will build separate boxes for each NRX so i can replace coaxial or fullrange by it's own box. my first start I'll use alpair 10p and SB16 coax, let's see how loud it can get.
btw i don't have any AVR yet, still long way to buy it because there still several audio project waiting. i really need to raise tv position because i want to put my tube dac on top of my rack (black chassis on lower rack which collect heat alot) which block tv view
I've never auditioned the LS 50, could be the simplistic x-over! Too much overlapping, have no idea? Mine coaxes are fine with movement of a meter at 3m distance
toe in!
if there is no toe in and one moves to left from listening position, the left speaker gets more on axis as well as closer to you making it appear louder. Opposite happens to right speaker which gets further away and more off axis and will get quieter. Image will jump to the left speaker. This is very unstable condition for stereo image.
On the other hand with toe in in front of listening position: if you move left, the left speaker would get closer but you'd be more off axis which compensates. For the right speaker you would get further away but bit more on axis which again compensates. This makes image much more stable and it should stay relatively constant despite you moving left or right.
This is trick that omni speakers can't do but narrow directivity can. If you have narrow constant directivity very good sound results, spectral balance and stable stereo image across the whole sofa at least, perhaps for most of the room.
if there is no toe in and one moves to left from listening position, the left speaker gets more on axis as well as closer to you making it appear louder. Opposite happens to right speaker which gets further away and more off axis and will get quieter. Image will jump to the left speaker. This is very unstable condition for stereo image.
On the other hand with toe in in front of listening position: if you move left, the left speaker would get closer but you'd be more off axis which compensates. For the right speaker you would get further away but bit more on axis which again compensates. This makes image much more stable and it should stay relatively constant despite you moving left or right.
This is trick that omni speakers can't do but narrow directivity can. If you have narrow constant directivity very good sound results, spectral balance and stable stereo image across the whole sofa at least, perhaps for most of the room.
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that have never worked for me, aiming the speakers so they crosses in front of me, for me the tonal balance of the speakers then goes f¤¤ked up
i would not recommend the sb16 coax driver, the tweeter response and its lowish output level is not as great as one would hope for, going active might work a little better since one can easily adjust for the low tweeter level
Yeah tonal balance will be off if the speaker is not designed to be listened this way, toed in front of listening postiion, like 99% of speakers that are designed with on-axis frequency response only. The old way of doing things. I don't know what is recommended for the LS50 but as a coax it will have narrowish directivity for tweeter (compared to direct radiating tweeters) and would benefit from toe in if considering the stereo image stability alone. One has to remember not to judge speaker without explaining how it was used, because it might be situation not recommended by the manufactured, something that the speaker was not designed for. Can't have speaker that works always on every situation, they all are designed for some application and can be misused and judged wrong. Operator error thats all. Well, can be poor design as well.
This is one reason why "spinorama" is a thing, to be able to tune the speaker for actual listening situation and not just for anechoic on axis listening situation, which happens never.
Constant directivity stuff is the pinnacle to this methodology. Design axis is about 15 degrees instead of dead on. To get speakers angled 45 degrees to avoid splaying the walls and have the optimal equilateral triangle stereo listening setup (60 deg) while maximizing /stabilizing sweetspot, have equal spectral balance through out most of the room while minimizing early reflections. Here design axis is exactly to the sweetspot while considering rest of the room and things as well. A bit further developed system than one which ignores this stuff altogether. One could design for certain amount of particular early reflections as well while minimizing others. Constant directivity, at least for wide bandwidth, is quite rare because it gets complicated and usually very big. Any attention to directivity would help I'd say, which is not too hard or complicated, just needs to be taken account.
This is one reason why "spinorama" is a thing, to be able to tune the speaker for actual listening situation and not just for anechoic on axis listening situation, which happens never.
Constant directivity stuff is the pinnacle to this methodology. Design axis is about 15 degrees instead of dead on. To get speakers angled 45 degrees to avoid splaying the walls and have the optimal equilateral triangle stereo listening setup (60 deg) while maximizing /stabilizing sweetspot, have equal spectral balance through out most of the room while minimizing early reflections. Here design axis is exactly to the sweetspot while considering rest of the room and things as well. A bit further developed system than one which ignores this stuff altogether. One could design for certain amount of particular early reflections as well while minimizing others. Constant directivity, at least for wide bandwidth, is quite rare because it gets complicated and usually very big. Any attention to directivity would help I'd say, which is not too hard or complicated, just needs to be taken account.
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Sorry Irealized being off topic! 🙂 Input for horizotal MTM:
there is going to be issues with horizontal polars, because the coax will radiate to sides and diffract from the woofers there. How severe? probably doesnt matter. The woofers could be at the ends of the enclosure instead on the front to reduce some enclosure resonance perhaps, and put crossover low enough so they are within roughly 1/4wl apart to keep the system omni. Unless there is reason to do something else for easy passive crossover.
MTM seems to make about an octave worth of narrow directivity, which might be usable to reduce problematic ceiling/floor relections, but for horizontal arrangement I don't know why would one want to have it without as narrow polars above as well (waveguide). There is no point with MTm setup woth coaxial either, since the coaxial has wide directivity since the woofer part is direct radiating. Narrowing response again below this would be counter productive. Basically, the woofers could and should be somewhere else than disturbing the horizontal response of the coaxial.
Never had one so my text is just a thought experiment.
there is going to be issues with horizontal polars, because the coax will radiate to sides and diffract from the woofers there. How severe? probably doesnt matter. The woofers could be at the ends of the enclosure instead on the front to reduce some enclosure resonance perhaps, and put crossover low enough so they are within roughly 1/4wl apart to keep the system omni. Unless there is reason to do something else for easy passive crossover.
MTM seems to make about an octave worth of narrow directivity, which might be usable to reduce problematic ceiling/floor relections, but for horizontal arrangement I don't know why would one want to have it without as narrow polars above as well (waveguide). There is no point with MTm setup woth coaxial either, since the coaxial has wide directivity since the woofer part is direct radiating. Narrowing response again below this would be counter productive. Basically, the woofers could and should be somewhere else than disturbing the horizontal response of the coaxial.
Never had one so my text is just a thought experiment.
my listening distance is 3.2m with 2m sofa right in the center. I always sit with center position for sure, my children have to sit beside me. so really on axis that matter for me 🙂
I just ordered the cabinet to my friend, estimated around 13L volume for each SB17NRX. center square box is separated, so I can replace it later with any 5" or 6" fullrange or coax.
it will be passive xo which i have to try but trying to make it simple. btw because this is center channel which mainly for dialog, i don't think too much sophisticated requirement is needed
drivers on my watch list : Satori MR16P or 13P, SS 10f. above pro driver celestion or faital pro might have too much sensitivity compared to NRX
I just ordered the cabinet to my friend, estimated around 13L volume for each SB17NRX. center square box is separated, so I can replace it later with any 5" or 6" fullrange or coax.
it will be passive xo which i have to try but trying to make it simple. btw because this is center channel which mainly for dialog, i don't think too much sophisticated requirement is needed
drivers on my watch list : Satori MR16P or 13P, SS 10f. above pro driver celestion or faital pro might have too much sensitivity compared to NRX
