help me choose a wide range driver

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frugal-phile™
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johninCR said:
An array gives you a sound image to match your large video image. With power tapering you can achieve great imaging and the distance vs SPL advantage of arrays makes for a very much larger sweet spot and it makes off axis listening more balanced than is possible with ANY point source speaker

Very true... when we finally get HD3D up & happening again, the sound system will be very tall line arrays with horns on the bottom for all those same reasons

dave
 
Dan thanks for input.
I have not seen any off-axis freq response posted so I was just fishing for input from anyone who may have some experience with the extremis. My plan seems to have changed from when I originally posted this thread. I thought I wanted a single driver to cover the 120- 5000hz range, but I don't think this is possible given off-axis coverage requirements for home theater, which in my house is just as important as music.

I do know that I like the sound of midwoofer on open baffle, since I have played around with several on a test baffle using an adjustable active crossover. At low volumes, I prefered them running all the way down to around 100, but obviously all the 5" drivers ran out of excursion at higher volumes. At the high end I either liked to cross to tweater below 1500hz or much higher above 4k. Placing the mid/tweater crossover between those 2 extremes just didn't sound right. I realize that most of 2-ways I have seen or read about use a crossover in the 2-2.5k region, but it doesn't sound right to me.

I do have a few Scanspeak 1.5" tweaters that can cross that low using a 4th order active and that there is a whole school of Linkwitz deciples who swear by the Orion design.
 
Dave,

Are you going to try a center channel (bessel maybe) ? I've tried a few different things and with the big image I always find the phantom center best because I don't like the supposedly sonically invisible screens and having the center channel at the top or bottom just doesn't work for me. I always localize it too high or too low. Is there something I'm missing?
 
frugal-phile™
Joined 2001
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johninCR said:
Are you going to try a center channel (bessel maybe) ?

With 3D we need as much light as possible, so want to avoid the holes in the screen usually required for a centre channel. So we will try to get away without. The line arrays, and the increased distance to the 1st row required for digital projection will help a lot.

dave
 
I've heard the B200 is a fine driver to run full range. On OB an uptilted response is less objectionable because the rear wave doesn't have the high frequency content, so until you get down to where the bass starts rolling off due to the dipole effect, you actually pick up some efficiency from the rear wave.

Unless something comes out that is as economical, is as highly touted, and has at least a mid Q, they will be my next driver purchase.

I wouldn't stick any XO in their path until after I good runin period and felt it was still necessary. I like my bass nice and full, so I'd add a woofer for bass fill, keep the baffle small (maybe a U baffle for the woofer) and decide after listening where to roll the woofer off 1st order. Probably at more like 80-100hz. You'll want a good highish Q woofer that sounds good up to 1khz or so, because it will give you a lot more flexibility.
 
For high SPLs with small drivers...

For high SPLs with small drivers use a Bessel array. A 5-element or 7-element Bessel array would work very well. The advantages of a Bessel array are a higher power-handling, and hence SPLs, and that the drivers together mimmick the off-axis response of a single unit. The disadvantages are a low total impedance, and that you would have to sit a bit further away than the norm (at least the distance equal to five times the length of the array).

Say you go for a 7-element array, the you only need 6 drive-units per side. In a 7-element array the 7th position, which is in the middle, is left blank. This will allow you to mount a tweeter there and have a co-axial 'driver'. If you go for a fullrange driver like the small Tangbands and the Fostexes (and don't want much output above 20kHz), then you can use a 5-element array.

Let's look at a quick example. A 5-element array using 3" drivers will be +/- 16" long (or high), therefor you'd have to sit at least 40" (or 1 meter) away for the drivers to integrate properly. If you can get 16-ohm drivers then that would work the best, as your total impedance would not be so low (unless you go full-active and drive each driver with it's own amp :bigeyes: ;) :D ). If you want more info on the Bessel array just let me know. :)

Enjoy,
Deon
 
Deon,

I've tried the 5 and 7 element bessels and find the only real advantage is the point source dispersion. The spl gain is minimal because of the way it is wired. The big problem is the lack of imaging, like a big wall of sound coming out from between the speakers with no distinct audio image. Quite a strange to say the least. I've thought it would be great for something like a bar where a imaging isn't necessary.

Where the Bessel becomes a significant increase in SPL is with something like the 5 x 5 array where you use 25 drivers that have the dispersion of a point source speaker.
 
Thanks for the heads-up re. Bessel arrays

I was at times seriously considering a Bessel array, but imaging is somewaht important to me so that idea has been shelved. :) OTOH for an HT system where imaging capability is of lesser importance (thanks to the center channel speaker) Bessel arrays might still be worth it. IIRC Stryke has some $3 drive-units that will work nicely in a 5 X 5 element array. :smash:

Enjoy,
Deon
 
I'm using a Phy-Hp 8" wide range driver on an open baffle from 120HZ to 4kHz with 60db/oct fir crossovers. The Phy's are driven by a 9W 300B set amp and have a effiency of 93db (97db/1w/1m/16Ohms but only 93dB/2.83V/1m). Power of the 300B amp is just about enough, in fact I would like to see at least the double amount of power on them for better transient response at higher volumes. So I think the use off a 300B set amp with the visaton's in a similar configuration would not be such a god advice unless you only play at lower volumes.

In a setup like this forget about using anything smaller than 8", they all run out of steam very easily no matter how high the xmax is.
 
I recently looked at a few drivers that might just be what you are looking for. They are the Madison Knight 8, Archer 8 or Warrior 10 (the name corresponding to the size). The specs look like this:

Model Knight 8
FS 90hz
VAS (cu.ft) 0.15
SD 38.484
Qts 0.683
Qes 0.812
Qms 4.313
BL 47.57
Re 5.3
Nominal Ohms 8
Le 232.92u H
Mms 64
X max 0.25
X mech 0.5
SPL 95db
Freq.Res. 80-8000hz
Cone type treated paper
basket type cast aluminum
Magnet size 30oz.
Power RMS 200 watts
Power Peak 400 watts

Model Archer 8
FS 81hz
VAS 0.643
SD 38.484
Qts 0.97
Qes 1.08
Qms 8.91
BL 7.07
Re 5.81
Nominal Ohms 8
Le 242.38u H
Mms 18.31
X max 0.187
X mech 0.375
SPL 98db
Freq.Res. 80-8500hz
Cone type treated paper
basket type stamp
Magnet size 20oz.
Power RMS 100 watts
Power Peak 200 watts

Model Warrior 10
FS 65hz
VAS 0.555
SD 63.61
Qts 0.867
Qes 0.915
Qms 16.35
BL 13.84
Re 6.17
Nominal Ohms 8
Le 362.56uH
Mms 53.06
X max 0.25
X mech 0.5
SPL 99db
Freq.Res. 80-7000hz
Cone type paper
basket type stamp
Magnet size 50oz.
Power RMS 200 watts
Power Peak 400 watts

If I use Thorsten's XL Baffle, and I plot them on an open baffle with a width of 12" (300mm), and a height off the floor of 27.5" (700mm), then both the Archer 8 and Warrior 10 give more than 110dB down to 100Hz (this is for a single driver). In fact, they both are around 115dB down to about 300Hz, but the version of XLBaffle that I am using here (I am not on my home PC right now) is an older version of XLBaffle, and the newer version also takes into consideration the height of the baffle (this version does not). If height is added to the calculation (for say a baffle that is about 43" (1100mm) high) then the total SPL will probably be flat at around 115dB right down to 100Hz, which should be ideal for your use. Consider though that this is for the full power handling spec of the driver (which is 100W for the Archer 8, and 200W for the Warrior 10). Still not too bad though. You can then use your two 10" drivers to fill in the lower octaves. Just a thought. :D

Enjoy,
Deon

PS. The link to have a look at the specs for the Madison drivers is:
Madison drivers T/S parameters

Their website is:
Madison Speakers

PPS. Their quoted VAS specs seem to be odd. I am not sure in what unit it is. I multiplied it by 100 to get to liters, as that seems to fit the rest of the specs best.
 
Re: Thanks for the heads-up re. Bessel arrays

DeonC said:
I was at times seriously considering a Bessel array, but imaging is somewaht important to me so that idea has been shelved. :) OTOH for an HT system where imaging capability is of lesser importance (thanks to the center channel speaker) Bessel arrays might still be worth it. IIRC Stryke has some $3 drive-units that will work nicely in a 5 X 5 element array. :smash:

Enjoy,
Deon

For HT with a big image I highly recommend a pair of real line arrays, then you can play around with the bessel as a center channel and horizontal mounting.
 
frugal-phile™
Joined 2001
Paid Member
Re: Re: Thanks for the heads-up re. Bessel arrays

johninCR said:
For HT with a big image I highly recommend a pair of real line arrays, then you can play around with the bessel as a center channel and horizontal mounting.

Keep in mind that for a bessel array you need to be listening in the far field for it to integrate and with the line arrays you want to be in the near field.

dave
 
Re: Re: Re: Thanks for the heads-up re. Bessel arrays

planet10 said:


Keep in mind that for a bessel array you need to be listening in the far field for it to integrate and with the line arrays you want to be in the near field.

dave

I agree, but since you're talking about apples and oranges, it's pretty easy to be in both fields at the listening position. The bigger problem is the efficiency mismatch with the line arrays being much more sensitive.
 
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