Hi efficiency 8 inch midrange - recommendations?

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BHTX

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Joined 2006
I'd use a 21" all the way up to 500+ Hz or so if I had to, but that's just me. If you don't mind the nasty high order xovers (4th+), I figure a pair of 21" woofers mated low to a 2" horn, MTM style, would be cool and different. Big theater or something. It'd rawk. :cool:

However, I also get the screaming thing mentioned, and I've always experienced this as well. I think it seems worse with drivers that aren't full range (steep roll off of the driver might partially have something to do with it?)
 
T

tinitus

Ex-Moderator R.I.P.
Joined 2005
15" http://www.faitalpro.com/products/schede/ps.php?id=101060100

http://www.precision-devices.com/asps/uploads/super/79.pdf

http://www.precision-devices.com/asps/uploads/super/73.pdf

18" http://www.faitalpro.com/products/schede/fhs.php?id=151070100

http://www.precision-devices.com/asps/uploads/super/49.pdf

http://www.precision-devices.com/asps/uploads/super/72.pdf

21" http://www.precision-devices.com/asps/uploads/super/85.pdf

Economically out of my reach at the moment, considering the CD/waveguide needed
 
B

BHTX

Member
Joined 2006
For large woofers under 500 Hz, to hell with all the expensive stuff, IMO. Well, that is, if you're on a tight budget, and want the most for your money, like me..

http://www.pyleaudio.com/itemdetail...Audio&cat2=Replacement Woofers&model=PDW21250

Can be had for $150ish each if you look around.
Parts Express has them for $200..

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=292-2526

Magnetar (banned) and a few others have used them.

I have some T/S parameters that Magnetar provided in a thread that was moved to Texas, if anyone wants them.

I'd be really interested in seeing some response measurements though.
 
M

MisterTwister

Member
Joined 2006
twisterspeakers.blogspot.com/
those have very inconsistent T/S.
if you are ordering a pair, get it from the same vendor.
otherwise, build quality is excellent.
measured on 2ftx2ft baffle sitting on the floor, non gated, on axis. I don't remember mic distance.
 

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Brett

Brett

Member
Joined 2002
MisterTwister said:
yes, that would be very interesting what some knowledgable people think on this subject. maybe someone has done some research already, and we are here just making guesses based on personal listening tests.
Click to expand...
I already have and have reviewed all the engineering info I can get on the subject, as well as my own tests. However the other poster didn't seem to know what they were talking about and I wanted to see if they had some useful ibfo I didn't.

I have been using pro drivers for years and they work extremely well in domestic use, if you use them correctly.

My two current build projects are my Unity mains which will use an AE15 pair/channel to 300Hz (where the Unity comes in, not because of the 15's performance). The sides and rears in the system will be JBL 2241 crossing to an AE TD10M at 300-350Hz and to a DE250 at about 1k6 (XT1086) where the directivity matches.
 
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John_E_Janowitz

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Joined 2004
aespeakers.com
a.wayne said:

On Single sinusoidal waveform the measurement flatters to deceive with such a large surface area Driver. THD rises exponentially when feed with multiple waveform as in real music .
Click to expand...


The main reason THD rises a lot with the multiple waveforms is due to motion of the driver at the lower frequencies. This gives two effects. The Le(x) is the change in inductance with excursion. The Le(i) is flux modulation due to the coil's magnetic field modulating the permanent magnetic field and changes depending on how much power is applied. Klippel has a good poster showing all of the loudspeaker non-linearities here:

http://www.klippel.de/download/Nonlin/Klippel_nonlinearity_poster.jpg

here is the overview of symptoms:
klippel-symptoms2.jpg


The big issues are not only what happens in the sound pressure domain but what happens in the current domain as well. The Le(x) changes the impedance curve which changes the current applied to the drivers. It also completely changes the way a passive xover works. In the case of the TD woofers, neither of these issues have much effect at all due to the full copper sleeve on the pole. The distortion is not there and the xover will function the same at various excursions and power levels.

TD12M Le(x)

http://sites.google.com/site/driver...ts/tang-band-75-1558se/ae-speakers-td12m/le-x

Contrast that to the Altec/GPA 414 and you can see how much the impedance curve changes with excursion. At 1KHz impedance is double on the inward stroke as it is on the outward stroke.

http://sites.google.com/site/drivervault/driver-measurements/tang-band-75-1558se/gpa-altec-414/le-x

So when you take a low frequency tone with high excursion and then play a high frequency tone on a driver where Le varies wildly, this is where the distortion skyrockets. Flux modulation also becomes an issue at higher input levels. The full copper sleeve on the TD pole addresses both issues.


John
 
GM

GM

Member
Joined 2003
John_E_Janowitz said:
The Le(x) changes the impedance curve which changes the current applied to the drivers. It also completely changes the way a passive xover works.

Contrast that to the Altec/GPA 414..........
Click to expand...

And why Altec used impedance compensation in some of its XOs for some driver/apps, including the 414. Presumably, it was cheaper to add the network than make an already high manufacturing cost driver even more so.

GM
 
M

MisterTwister

Member
Joined 2006
twisterspeakers.blogspot.com/
B

BHTX

Member
Joined 2006
hndaaudio said:
I am interested in the T/S parameters for the 21 Pyle.
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Here's what I entered in WinISD from Magnetar's findings. I could be wrong, but I'm thinking the Bl was entered too high on what GM posted (39 Tm vs my 32.88 Tm), so some other parameters are different on that one as well, like Sd.. his 1992.7 cm^2 vs my 1680 cm^2. IIRC, Magnetar didn't mention Mms, so I filled in Sd first by looking at other 21" woofers. So, that's why mine is different. Of course, neither of them are 100% correct, and as previously mentioned by someone else, there's very low consistency between drivers anyway. However, I'd say this represents a good idea of what to expect. Likely a very stiff suspension, and a high Bl (350 oz magnet, supposedly). I just wish I had a reliable Xmax figure, though..

Qes .38
Qms 4.03
Qts .347
Fs 31.61 Hz
Vas 274.29 l

Mms 370 g
Cms 68.5 um/N
Rms 18.2366 Ns/m
Re 5.59 ohm
BL 32.88051 Tm
Dd 46.25 cm
Sd 1680 cm^2

Xmax ? (wish I knew)
Pe 1000 W

no 2.2171%
Znom 8 ohm
USPL 97.17 dB
SPL 95.61 dB
 
B

BHTX

Member
Joined 2006
Also, even if xmax was only 4 mm, two of these woofers per side in IB would get you around 110 dB anechoic at 30 Hz, with an overall output of around 112.5 dB anechoic, if EQ'd to an f3 of 27 Hz with .58 Qtc. If they can play clean enough pushed to 5 mm, that'd be 114.4 dB anechoic with 112 dB at 30 Hz under the same conditions. I've seen these things selling online as low as the $130-$140 range (shipping not included). So, no matter what, it's most likely still a pretty good deal.. unless Xmax really is just insanely low or something.

And.. I just noticed that was Magnetar at hometheatershack. I didn't know he was an admin there, lol. Cool. :)
 
GM

GM

Member
Joined 2003
BHTX said:

I could be wrong, but I'm thinking the Bl was entered too high on what GM posted (39 Tm vs my 32.88 Tm), so some other parameters are different on that one as well, like Sd.. his 1992.7 cm^2 vs my 1680 cm^2.
Click to expand...

No, you're right enough, it took me awhile to unravel the 'comedy of errors' that occurred when I mis-typed a value awhile back when I posted the specs on another thread. I'd actually reverse engineered Sd, BL in Hornresp, winding up with 1686.87 cm^2, 33.1 N/A, but inputted the bad info in WinISD and it calculated an even higher Sd. Factor in that I'm still a 'newbie' WRT its calculating quirks and was in a hurry, so didn't check it as carefully as I should have..........

Anyway, thanks for pointing it out, I've corrected/reloaded the 'wdr' with specs I believe we can both agree on for now. :)

GM

edit: just tried both sets of specs in HR and the sims are a perfect overlay except for a minor difference in the acoustic efficiency of the larger Sd, so for all the 'wrong', it was 'right' enough.
 
B

BHTX

Member
Joined 2006
diyAudio is undergoing maintenance. We'll be right back!

I just typed a fairly lengthy post, couldn't submit it and lost it because of this. Pissed me right the hell off. :mad:

Oh well, I guess it really doesn't belong here anyway. It was mainly just me rambling some thoughts about a potential project in the near future with these woofers. I'll probably just start another thread at some point.
 
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