I'd like to get some opinions on the pros & cons of using 12" midrange vs 15" midrange, when you will always have subwoofers & those are crossed at either 100Hz or 120Hz. (I prefer 100Hz, when design allows it)
This is for Rock Band / DJ applications.
I used to believe that the smaller speaker gave better transient response, and so thus sounded better for vocals, but these days I'm pretty sure that's not true. In fact, the 15" might be cleaner since it has less modular & even order distortion, for a given dB.
Also, theoretically the 15" should be a bit more efficient, which never hurts, although looking at the specs of a number of drivers, the sensitivity difference is often only 1 dB, or less, which I find surprising.
Another factor for me is that I am considering coaxial drivers, and that might make a difference since the cone thus has a little less surface area.
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I also would be looking to keep the enclosure on the small side, if using a 15", which should be fine since, again, I'd never try to use these without subs, anyway.
All thoughts / opinions welcome.
This is for Rock Band / DJ applications.
I used to believe that the smaller speaker gave better transient response, and so thus sounded better for vocals, but these days I'm pretty sure that's not true. In fact, the 15" might be cleaner since it has less modular & even order distortion, for a given dB.
Also, theoretically the 15" should be a bit more efficient, which never hurts, although looking at the specs of a number of drivers, the sensitivity difference is often only 1 dB, or less, which I find surprising.
Another factor for me is that I am considering coaxial drivers, and that might make a difference since the cone thus has a little less surface area.
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I also would be looking to keep the enclosure on the small side, if using a 15", which should be fine since, again, I'd never try to use these without subs, anyway.
All thoughts / opinions welcome.
FR units Fane 12-250TC or the 15" FC152 but they like sealed boxes, do not know how hard you will push them.
Coax can be anything, Faital, Beyma, Radian etc. long list.
Small box easier to get "right" with 12" if you want a small bass reflex. Difference may be 1 db at higher frequencies, but can be a little bit more at 100hz. Check measured response closely, run a lot of sims.
Coax can be anything, Faital, Beyma, Radian etc. long list.
Small box easier to get "right" with 12" if you want a small bass reflex. Difference may be 1 db at higher frequencies, but can be a little bit more at 100hz. Check measured response closely, run a lot of sims.
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Off axis response is key. I would only use 12 or 15 inch drivers in 3 way or with a very expensive tweeter crossed over low (1kHz).
I would take (double?) 6.5"or 8" tops over 12" or 15" tops.
Why manufacturers sell those inferior 2 way 12" or 15"cabs? Because the worthless specs look good and people buy them.
I would take (double?) 6.5"or 8" tops over 12" or 15" tops.
Why manufacturers sell those inferior 2 way 12" or 15"cabs? Because the worthless specs look good and people buy them.
1)AM(Amplitude Modulation) distortion is not an issue unless the driver is driven past Xmax. THD (Total Harmonic Distortion) is far more driver construction dependent than size dependent, though Xmax has a lot to do with it. 12" and 15" drivers used for PA "speaker on a stick" range from an Xmax as low as 2mm to a high of around 6mm.
A 12" with an Xmax of 6mm will beat a 15" with 2mm by about 6 dB.
2) The reduction in cone area for a co-ax is not much, but greater on a 12" relative to a 15".
3)The reduction in VAS of a 12" compared to a 15" allows it to be used in a smaller box, for a small size box a 12" may perform better.
Generically speaking, a 15" has around -6dB 90 degree dispersion at 1200 Hz, while a 12" can do that at around 1500 Hz.
Cheaper PA speakers use small diaphragm HF drivers, they often cross over to the HF higher than those frequencies, resulting in "beaming" in the midrange. Since the 15" has more output than 12", often the crossover point is pushed up to as high as 2kHz (or more) which puts the 15" in the nasty sounding cone breakup mode, which is still preferable to the sound of the HF diaphragm hammering the phase plug...
Generically speaking, when using a sub below, 12" will be a better value, smaller and lighter for output above 100Hz than 15" PA speakers.
Art
Thanks, guys.
I didn't know about the beaming / dispersion issue. 12" it is, but maybe I'll go slightly larger with the box than I had planned, for a smoother low transition, unless I find the "perfect" driver.
Also now thinking more carefully about where to set the xover, which of course affects the mid-driver selection as well. The Tannoy T300's cross at 1.7, and I love their sound, but a few good modern coaxials (Radian, B&C) recommend to be in the 950 - 1.2K range. That's mostly due to the response of the 12" / 15" but now I see the other benefit.
- But this requires a great horn, yes? And good heat dissipation, which I've read can be a problem with Neo magnets. I'm leaning hard now (If I do go coax) towards the Radian 5312NEO with the beryllim diaphram. (theoretically, less distortion when pushed hard / crossed low)
I didn't know about the beaming / dispersion issue. 12" it is, but maybe I'll go slightly larger with the box than I had planned, for a smoother low transition, unless I find the "perfect" driver.
Also now thinking more carefully about where to set the xover, which of course affects the mid-driver selection as well. The Tannoy T300's cross at 1.7, and I love their sound, but a few good modern coaxials (Radian, B&C) recommend to be in the 950 - 1.2K range. That's mostly due to the response of the 12" / 15" but now I see the other benefit.
- But this requires a great horn, yes? And good heat dissipation, which I've read can be a problem with Neo magnets. I'm leaning hard now (If I do go coax) towards the Radian 5312NEO with the beryllim diaphram. (theoretically, less distortion when pushed hard / crossed low)
That's the other design I've considered. Actually, something like the Fulcrum FA28 here one 8" driver handles the low mids, and the other, which contains the coaxial HF driver, has its LF point much higher. Interesting idea.
Presonus has a similar line, but made much more cheaply.
Oh, that Radian coaxial also has a 2" exit. (3" diameter) That should give a bit smoother sound at the transition, yes?
"All other things being optimized", Would you guys crossover at / near the minimum recommendation of 950 Hz, or go a little higher. the 12" is very flat through 2K, but of course the beaming is another issue. I'm not sure about that yet.
"All other things being optimized", Would you guys crossover at / near the minimum recommendation of 950 Hz, or go a little higher. the 12" is very flat through 2K, but of course the beaming is another issue. I'm not sure about that yet.
1) Smoother than what? Diaphragm size is not an indication of smoothness.
A 3" diameter diaphragm can operate lower than a 1.75" diaphragm, but the horn it is attached to (and the processing used) determines "smoothness".
2) Something that Fulcrum Acoustic does quite well, probably better than any other PA co-axial designs.
Fulcrum Acoustic uses proprietary horns for their co-axial designs, which have better polar response than any co-axials using the cone for the HF horn.
3) Without seeing the polar response of the LF/HF, making a recommendation for the Radian 5312NEO would be rather useless.
Radian's own 324/12 crossover network results in a 6 dB dip in the on axis response around 700 Hz, not very promising.
From what I remember of their other 12" coaxial's polar response, they have problems regardless of what frequency chosen.
Cheers,
Art
Art, you always seem to disagree with most of what I read elsewhere. (And I've done a TON of reading.)
It's a mystery.
I've read the same about the older Radians, also that their crossovers weren't all that good. - But the newer Neo series is completely different, as are their crossovers. I got some basic info from them today, but the main tech guy was out. Hopefully, tomorrow I can get some important data, including polar response.
I'm also hoping to get distortion measurements for the HF, with and without the beryllium drivers.
I agree with most transducer designers on what we consider important aspects of design.
If you look at the frequency response of a wide variety of compression drivers, you too will find diaphragm size is not an indication of smoothness.
That said, 3" diaphragms are a nice compromise between HF breakup modes and having enough diaphragm area for lower crossover points without excessive distortion while keeping up with today's higher excursion woofers.
I couldn't even find a photo of what the Radian 5312NEO cone/horn looks like, much less polar response.
Good luck with getting any more data than they offer on line!
Art has decades of real world experience. It would be wise to pay attention.
Art, they're in the process of updating their website right now. It's currently a bit of a mess & badly outdated.
No graphs at all for the beryllium version, and as you say no info on lobing, or anything at all the horns, other than dispersion angle. Dennis did say it's much like the Tannoy super duals, having a small conical waveguide behind the dust cap.
They don't even have full specs right now. What's listed is only for the 16 ohm version. (And it doesn't even say that.)
They JUST added info on the new (not yet available) passive crossovers.
I'll be calling Dennis again on Monday, & hopefully get more info, maybe some charts. As I've said earlier, I'd REALLY like to see some distortion measurements between the aluminum & beryllium diaphrams.
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There are other sold choices of course with a 12" coaxial.
The B&C 12CXN88 takes 580w with 100dB sensitivity, and is 80º conical, which I like better. - But they also don't show the horn, nor any polar response.
B&C also has the 12HCXN76, which has a larger, protruding HF waveguide and is 60 X 40. I assume that's intended for stage monitors, though it could also be interesting for mains. (Less smear from bouncing off the ceiling, floor & walls.) It might even throw farther, I dunno.
- But The Radian takes more power, has better sensitivity (700 watts & 102 dB total, 105w / 113bB for the horn) and it gives the option of a beryllium diaphram. - I may not need the Be, but it's nice to know it's available.
As with custom subwoofers, I sure wish I could actually HEAR these things before taking the plunge. That is, of course, the big downside to DIY.
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- Multiple threads on several RELATED topics, actually.
- These forum members are great. But it's so hard discussing things you can't actually HEAR. I am definitely comfortable now, though, sticking with 12's for the mid bass.
I'm hesitating on the Radians right now, only because I'm not sure I want to again have a 90º dispersion pattern. There are a few other options, as explained above. I don't think this is trivial: with 90º vertical, a lot of HF bounces off the ceiling and walls. Besides being wasted power (hence less throw) it also means that sound is combining at the audience level out of phase. How can that possibly be desirable?
- These forum members are great. But it's so hard discussing things you can't actually HEAR. I am definitely comfortable now, though, sticking with 12's for the mid bass.
I'm hesitating on the Radians right now, only because I'm not sure I want to again have a 90º dispersion pattern. There are a few other options, as explained above. I don't think this is trivial: with 90º vertical, a lot of HF bounces off the ceiling and walls. Besides being wasted power (hence less throw) it also means that sound is combining at the audience level out of phase. How can that possibly be desirable?
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i guess talking about cabinet "placement" in the other thread didn't turn on any light bulbs for you?
focusing the coverage pattern where you need it is the ticket but hey you've can't judge that without hearing it.
yes i agree it's hard to know "what to do when you can't hear it" it's worse when you seek advise on hypothetical's!
p.s. throw is a myth.
focusing the coverage pattern where you need it is the ticket but hey you've can't judge that without hearing it.
yes i agree it's hard to know "what to do when you can't hear it" it's worse when you seek advise on hypothetical's!
p.s. throw is a myth.
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90 degrees vertical doesn't turn on any lightbulbs for YOU? There's no way to "focus" the vertical dispersion.
Is HF throw a myth? Hmm.. gotta' think on this. If you take a given HF amplitude, and spread it 90 degrees, then use a waveguide to make that same energy, say 20 X 80 like a typical array module, that energy travels a lot further before losing power. That part is obviously true.
But OK, you'd then have too much HF energy near the speaker, so you'd have to adjust the xover or amp power, and then you're back to the same effective throw.
I assume that's what you mean?
But you'd be wasting less amplifier power to get the same volume out front.
Of course, in my case, that's not a big concern, so I guess you have a point.
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Still, I AM concerned about the phase smear. At the same time, my old Tannoy T30's were 90º conical, and they sounded rather incredible at 30-50 feet, so maybe I'm overthinking it.
- but I'm probably NOT overthinking it.
Maybe those T300's, with only 40º vertical, would have sounded even better. Tannoy's new flagship VX 12.2Q has a tighter waveguide, giving 75º x 40º, and it's being marketing as a FOH point source speaker, not a stage monitor. To quote the data sheet:
"The latest ... version of Tannoy’s exclusive point source .... drive unit technology, coupled with the QCW device, brings best of both worlds – true point source acoustical performance combined with highly controlled 75 x 40 degree dispersion, resulting in less unwanted shading effects and optimized forward gain."
90º conical would be ideal for a medium sized church or venue, doing a minimal installed system, hung from the ceiling & angled down. That would give deep coverage without the need for an array. - But for bars and weddings? It's just not ideal.
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most commercial venues have higher than standard home ceiling heights and most are employing drop ceiling with absorbent tile. so yes raising them and tilting the vertical axis down and toe'ing in reduces reflections and also points the hotter on axis response into (hopefully) the largest absorber in the venue the crowd, while not a perfect situation it succeeds quite well.
but telling you this is obviously another unheard, unassessed, hypothetical.
but telling you this is obviously another unheard, unassessed, hypothetical.
You realise these dispersion angles happen over a couple of octaves at best, right?
Above 10kHz or so, you get beaming since the HF exit diameter is fairly large. Below a couple of kHz, most horns are too small to effectively control the dispersion.
Time to look at Synergy horns...
Chris
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