Is it possible to cover the whole spectrum, high SPL, low distortion with a 2-way?

In a large room, 30Hz might get help from a mode. In a small room some help from pressurization with closed box driver. With eg. the Calpamos in previous post puts out 30-35Hz only from reflex ports, so expect high distortion! Typically bass is mixed in middle of stereo, so both speakers play it, this helps too.

Typical bass drum hit is however around 50Hz and pop/rock/reggae/dance hardly ever has high intensity below 50Hz, because this way people don't break their speakers so easily at parties. Syntehetic modern disco mixes might contain lower rumble, dunno for sure...

Mixing Bass |
7 Tips for Mixing the Low End
 
In a large room, 30Hz might get help from a mode. In a small room some help from pressurization with closed box driver. With eg. the Calpamos in previous post puts out 30-35Hz only from reflex ports, so expect high distortion! Typically bass is mixed in middle of stereo, so both speakers play it, this helps too.

Typical bass drum hit is however around 50Hz and pop/rock/reggae/dance hardly ever has high intensity below 50Hz, because this way people don't break their speakers so easily at parties. Syntehetic modern disco mixes might contain lower rumble, dunno for sure...

Mixing Bass |
7 Tips for Mixing the Low End

No particular reason a reflex box ought to add distortion. If anything, I'd expect cleaner sound because of reduced excursion from the LF driver.

I think this is the sort of music the original poster wants to reproduce:

YouTube (Caution - NSFW lyrics)
When the bass drops, it's a compressed 36Hz sine wave, which causes serious heat problems in a lot of drivers.

Here's another: YouTube

Modern electronic music goes all the way down, and the PA systems tasked with reproducing that stuff are usually capable of full power down to 25Hz.

FWIW, most pop music these days reaches down to the 40Hz region.

Chris
 
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Along these lines I think its possible. However much better results would be obtained using subs for <80Hz as this reduces distortions from the mid woofer.

HF: Test Bench: RCF ND950 Neodymium Compression Driver and HF950 Horn | audioXpress

Cross at 650Hz (apparently done by RCF in their speaker using this driver)

LF: Test Bench: Eighteen Sound 18iD 18-Inch Woofer | audioXpress

Only recommend up to 200 Hz but I can't see any obvious reason it would be a bad idea to use it higher in frequency apart from the the before mentioned large excursions at low frequencies causing distortion. This system would not behave as a point source as the HF and LF are not close enough together. Would need digital processing and 4 channels of amplification.
 
yes, the voice is cleaner in a 12" 2-way crossing at 100hz versus a double 15 crossing to a compression driver @ 750-1khz.

I don't see 117db from a 15" 2-way, I mean it is there and it will pound you more than a 12" 2-way crossed at 100hz, but dance music with sine waves, the voice will warble on the 1 or 2x15 plus compression driver.
 
chris661, have you played sine wave with a reflex ported peaker, at tuning or lower and 100-120dB at 1m. Turbulences are terrible, it sound is more like a car passing you 100km/h

There are calculators for this http://redspade-audio.blogspot.com/2010/06/winisd-how-to-design-vent-that-wont.html

http://jahonen.kapsi.fi/Audio/Papers/AES_PortPaper.pdf
http://www.bodziosoftware.com.au/PORTS.pdf

"This brief analysis of the vent performance clearly indicates, that nearly all practical size vents will compress at higher SPL levels. Loudspeakers intended for high power stage applications should be give very careful consideration regarding port non-linearity. For this type of application, port compression problem will tend to further degrade system SPL, already affected by the thermal compression during prolonged stage performance."
 
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chris661, have you played sine wave with a reflex ported peaker, at tuning or lower and 100-120dB at 1m. Turbulences are terrible, it sound is more like a car passing you 100km/h

Yes, I have.

The ported boxes I use have a port exit area of 0.6*Sd, and I have no problems getting 120dB 40Hz (tuning frequency) sine waves out of a single 15" cone.
When you try to reach 123dB, there's 2dB of compression so you actually get 121dB.

No bad noises, just a small loss in output.


I also accidentally ran high-power signals through the driver well below tuning. There was well over 500w going into the driver, starting at 15Hz on a fairly slow sweep. After a lot of unhappy mechanical noises from the driver, I noticed that the cone had developed some fold lines, so I had to get it reconed before I put it to use in the PA system.

Chris
 
OK......
I find that with a woofer, that has a ~35 or lower Fs, decreases xmax in the area I would like to extend to. Though many of the speakers with that parameter have a f3 high than the target range, the xmax and spl, allow EQ correction to numbers like 114db at 30hz. That is fine to me. The woofer would need to be able to be crossed around 800hz though. I'm doing my best to find a driver with all of that and great transient response. Looking for suggestions!

I'm looking at the BMS 4590 as a possible top driver. Maybe the FaitalPRO HF201 or Beyma CP-750Nd
 
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I too am doing some work with a 2 way monitor design. Seems to me the biggest issue is the behavior of a big cone taken well into its breakup region and that in a place the ear is quite sensitive to.

I have spent last 30 years listening primarily to full range ribbons and planers so not sure how much this has to do with it but I have not yet been able to get a larger woofer to sound as clean as I would like at anything above about 300 hz cross both in box and dipole
I admit to a limited experience with large woofers and maybe with one linear enough it can sound better but so far I struggle with the sound of big cones taken up to 800-1K hz.

My present system uses a PA12 mated to a ribbon at 1 khz. The ribbon sits in a wave guide approx 15 inches wide. Sensativity is 95 db.
It plays loud but not 120 db loud, and goes down to about 50 hz. Basically for me it simply doesn't go deep enough AND the big one is that I just dont think the big woofer is well enough behaved above about 3-400 hz to match well with the ribbon and I suspect a good compression driver would be the same?.

Im sure there are big cones that traverse this region better BUT I am skeptical that such a structure can sound as convincing as drivers operating closer to piston??

800 hz -1 khz seems about the limit to the more practical sized monitor so I suspect it will take a very well refined cone design in a 2 way to match the upper freq drivers character enough.
 
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Hello camplo

I figure you already know this but the M2 has it roots in the 1980's 4430 monitor. This system comes very close to range you are looking for at the SPL you are looking for. The 4435 gives even more headroom and bass extension being a 2 1/2 way. Food for thought and to give some ideas. They are also lots of them around so I am sure you can find a pair to have a listen.

Rob :)

http://www.lansingheritage.org/images/jbl/specs/pro-speakers/1984-4430-35/page06.jpg
 
Also TAD 2402


1458248574049122504.jpeg
 
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I think this woofer is the first good choice I've made
Ciare NDH15-4S - 15" Subwoofer
The low fs, high sens, very decent xmax, inductance is not on the high side.
With room eq, I can reach 114db at 30hz in a 2.1ft3

So finally I measured what my system is currently doing. 30hz 113db, with a way too much THD, due to the limiter and reaching the max specs of amp/driver combo. Its not that loud to me at all.
My reference track, "Drake - I'm upset" 808 tuned to 34hz (didn't somebody doubt me when I said rap and edm have 808's tuned to the 30's?) 105db and way too much THD.

I think I'd be more than satisfied with a woofer in the performance range of the one selected. My goal was to have rms power at max listening levels. CTS 1200 600watts rms, The ultimax 15 and the Ciare NDH15-4S are puling 110db at 30hz,

And then I found the trade off, 2ms of group delay over the Ultimax 15, 10ms total.
Ill have to keep looking to see if I can do better but I am making progress so, I am hopeful.
 
There's a counterpart to hoffman's iron law- it's probably been described before, but it's around bandwidth, distortion, and SPL(displacement). There are drivers that can do wide bandwidth and low distortion, but exceedingly low SPL (headphone drivers). As you increase the SPL requirement, you get more and more into focused designs oriented towards specific bandwith SPL capabilities. Xmax/size/Fs/power handling in woofers, traded off against voice coil inductance, breakup modes, etc, with the tradeoffs changing as you get into mids which need less Xmax, can have higher Fs and smaller diaphragm size but may still need very high power handling in the coils, and into a still different tradeoff for tweeters.

The very best 2 ways with high SPL/low distortion capability still trade extension and distortion characteristics in the top and bottom octaves, generally allowing them to simply roll off rather than forcing the issue (as with bad sounding PA speakers that will let the horn driver operate in nasty distorted breakup in the top octave).

Separate subs are generally the way to go regardless for reasons besides driver tradeoffs (I won't beat the multisub dead horse here), so you can relax the <100hz requirements (though I like to XO lower, around 60) which lets you worry more about the top end performance of the woofer, which in turn relaxes the tweeter requirements and opens up more bandwidth up high.
 
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