Let me add that the text claiming that it is a subwoofer is an error, probably cut and pasted from another page when they wrote the ad:
http://www.madisound.com/catalog/product_info.php?manufacturers_id=143&products_id=8499
http://www.madisound.com/catalog/product_info.php?manufacturers_id=143&products_id=8499
Pete-
That Peerless looks great! And it should drop right in. The price is right as well.
Unfortunately, I'm still undecided on the crossover points. This has been tough for me!
The one thing that's stopping me is the low XO point for the cone woofer. I'll have to buy large inductors UNLESS I settle on a 1st order filter. A pair of 5 mH coils will do the trick @ 250 Hz (which I already have). Will that work?
~~John~~
That Peerless looks great! And it should drop right in. The price is right as well.
Unfortunately, I'm still undecided on the crossover points. This has been tough for me!
The one thing that's stopping me is the low XO point for the cone woofer. I'll have to buy large inductors UNLESS I settle on a 1st order filter. A pair of 5 mH coils will do the trick @ 250 Hz (which I already have). Will that work?
~~John~~
Back chamber volumes for both midranges.
A) Aluminum cone midrange. 328 cu in required. Figuring the PVC has a wall of 0.125 inch, the ID is 5.75 in which yields a cross sectional area of 26 sq inches. To achieve 328 cu inches, that is 12.6 inches internal lengh. Final Qtc = 0.7. F3 down point = 80 Hz.
B) Peerless midrange. 388 cu in required. Length of PVC = 15 in. Final Qtc = 0.7. F3 down point = 80 Hz.
Calculations of Qtc and F3 are according to Small's formula, Small being of Thiele-Small fame.
Nothing preventing you from making the chamber a little larger and adding material to shrink the volume, so that differnt bass mids can be dropped in.
A) Aluminum cone midrange. 328 cu in required. Figuring the PVC has a wall of 0.125 inch, the ID is 5.75 in which yields a cross sectional area of 26 sq inches. To achieve 328 cu inches, that is 12.6 inches internal lengh. Final Qtc = 0.7. F3 down point = 80 Hz.
B) Peerless midrange. 388 cu in required. Length of PVC = 15 in. Final Qtc = 0.7. F3 down point = 80 Hz.
Calculations of Qtc and F3 are according to Small's formula, Small being of Thiele-Small fame.
Nothing preventing you from making the chamber a little larger and adding material to shrink the volume, so that differnt bass mids can be dropped in.
If you want to save a little money on your crossover, you might consider just letting the bass mid go up from 80 Hz on up with no crossover for the low end, and then using perhaps a first order crossover, (choke) on the woofer. But I'll let you discuss that with your crossover advisor, who is not me.
If you want a higher crossover but wish to use the natural rolloff of the bass mid/enclosure as a crossover element, you would require a 5 incher with either a higher Fs or a much lower Qts, which might or might not be available.
If you want a higher crossover but wish to use the natural rolloff of the bass mid/enclosure as a crossover element, you would require a 5 incher with either a higher Fs or a much lower Qts, which might or might not be available.
TubeHead Johnny said:
I've done similar 3-way crossovers before and I'd say yes, 5mH is about right to provide a good amount of BSC and a 250 Hz XO, however I'd add a 100 uF - 2 ohm "zobel" where the resistor is deliberately small to provide a 2nd order electrical rolloff. The resistor is required to avoid resonance with the woofer VC inductance. Mid and tweeter might have to be out of phase with the woofer.
It is very difficult to design a crossover without driver measurements so consider it an initial ball park.
You can run the mid cavity much smaller to raise the mid Fc and use the acoustical rolloff as a second order section for the mid HP. Tightly stuff the cavity toward the back but leave about an inch or two behind the cone to avoid mass loading that will further reduce the midrange efficiency.
Pete B.
That is what he is saying.
Also, normally making the cavity much smaller will raise the F3 higher but also make the Qtc too high, resulting in a hump in the response. But I think he's saying the extra stuffing will compensate, if there is enough of it.
Also, normally making the cavity much smaller will raise the F3 higher but also make the Qtc too high, resulting in a hump in the response. But I think he's saying the extra stuffing will compensate, if there is enough of it.
I will have to determine the length of the tube and amount of stuffing to use for a 250Hz roll off.
TubeHead Johnny, I think I've come up with something. The network will recycles almost all of the caps & coils from the x-o you have now, adding just a few more componnents. My modelling uses the Dayton DC130BS-4 and an assumed listenning height of 18" above the tweeter. It is far from perfect, but also far from what you'll get at a big box store for $1000.
Tweeter-
second order @~2.5 to 3kHz, 4.7uf cap, 0.5mH coil
Midrange-
first order highpass @~300 to 350Hz, 100 uf cap
second order lowpass @~2.5 to 3kHz, 0.5mh coil, 4.7uf cap
Zobel 25uf cap and 3ohm resistor,
1ohm padding resistor last before the driver
polarity reversed
Woofer-
first order @~250 to 300Hz, 5.1mH (4+1.1) coil
Zobel 100uf cap and 2ohm resistor
This layout offers +/- 4dB from 100Hz to 15kHz, a minimum 4ohm load, reasonable phase tracking, and a good attempt at building in BSC. Use a 1, 2, or 3ohm resistor inline to bring down the tweeter to taste, adjust the 2ohm on the woofer Zobel up to 4ohms for BSC and midbass character, adjust the 3ohm on the mid Zobel up or down by 1ohm to contour upper-midrange voicing and possibly overall character at listenning position, and adjust the 100uf highpass cap on the mid no higher than 200uf for midbass bite. Also, tweeter polarity can be reversed according to listenning height, as a last resort if there is any problem with suckouts.
It looks like all you'll need to buy is a couple of coils, some cheap electrolytic caps (too bad about the huge value on the 5"), an assortment of resistors to play around with, and the drivers. The PVC doesn't need to be much longer than 6" or 8", stuffed to taste. I have enough confidence on this layout that I would build this if someone commisioned me to do a classic three way.
Tweeter-
second order @~2.5 to 3kHz, 4.7uf cap, 0.5mH coil
Midrange-
first order highpass @~300 to 350Hz, 100 uf cap
second order lowpass @~2.5 to 3kHz, 0.5mh coil, 4.7uf cap
Zobel 25uf cap and 3ohm resistor,
1ohm padding resistor last before the driver
polarity reversed
Woofer-
first order @~250 to 300Hz, 5.1mH (4+1.1) coil
Zobel 100uf cap and 2ohm resistor
This layout offers +/- 4dB from 100Hz to 15kHz, a minimum 4ohm load, reasonable phase tracking, and a good attempt at building in BSC. Use a 1, 2, or 3ohm resistor inline to bring down the tweeter to taste, adjust the 2ohm on the woofer Zobel up to 4ohms for BSC and midbass character, adjust the 3ohm on the mid Zobel up or down by 1ohm to contour upper-midrange voicing and possibly overall character at listenning position, and adjust the 100uf highpass cap on the mid no higher than 200uf for midbass bite. Also, tweeter polarity can be reversed according to listenning height, as a last resort if there is any problem with suckouts.
It looks like all you'll need to buy is a couple of coils, some cheap electrolytic caps (too bad about the huge value on the 5"), an assortment of resistors to play around with, and the drivers. The PVC doesn't need to be much longer than 6" or 8", stuffed to taste. I have enough confidence on this layout that I would build this if someone commisioned me to do a classic three way.
This is AWESOME pwater!
Just a some quick questions:
1) The DC130BS-4 requires a 4.75" hole and the 6" PVC I'm using for the back chamber has 0.25" walls, which brings the ID down to 4.5". Will that be a problem? I also have to enlarge the existing hole.
2) The Peerless 830656 5.25" that PB2 recommends will drop right in. How hard would it be to substitute?
3) How long should I make the chamber?
Thank you!!!!!!!!!
~~John~~
Just a some quick questions:
1) The DC130BS-4 requires a 4.75" hole and the 6" PVC I'm using for the back chamber has 0.25" walls, which brings the ID down to 4.5". Will that be a problem? I also have to enlarge the existing hole.
2) The Peerless 830656 5.25" that PB2 recommends will drop right in. How hard would it be to substitute?
3) How long should I make the chamber?
Thank you!!!!!!!!!
~~John~~
TubeHead Johnny said:
No, I'm saying that the acoustic response could be one 2nd order section of a 4th order by adding an electrical 2nd order, or 3rd total by adding 1st electrical.
You might want to consider using a free measurement package:
http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=4737
Even a simple RTA is better than nothing.
Pete B.
Something like this?
An externally hosted image should be here but it was not working when we last tested it.
Something exactly like that, except insert a 1ohm resistor inline just before the mid, after the x-o components.
I just got back after a long day out, and after looking at the model again, I'm excited about the response and especially the tunability, which is something I have been trying to implement for awhile. The small changes possible that I outlined above are profound enough to alter the voicing with little hassle or drawback. Room conditions, listenning position, personal preferance... jump in.
Take note that the 5.1mH coil is two coils in series that you already have- a 4mH and a 1.1mH. Another 1.1mH could even be added if there's too much upper bass. And to anyone who may wonder, I did use realistic coil DCR values in the model.
I just got back after a long day out, and after looking at the model again, I'm excited about the response and especially the tunability, which is something I have been trying to implement for awhile. The small changes possible that I outlined above are profound enough to alter the voicing with little hassle or drawback. Room conditions, listenning position, personal preferance... jump in.
Take note that the 5.1mH coil is two coils in series that you already have- a 4mH and a 1.1mH. Another 1.1mH could even be added if there's too much upper bass. And to anyone who may wonder, I did use realistic coil DCR values in the model.
FYI those series coils should be spaced apart, or they will interact to form an inductance greater than 5.1
kelticwizard said:
Hi,
Not to put too fine a point on it the above is one of the original
causes of the problem in the first place and is not a good idea.
🙂/sreten.
I plan on placing the woofer and tweeter/mid components on 2 different boards.
fwater-
Will I have any problems subbing the Dayton 5.25 for the Peerless?
I did a T/S parameter comparison between the drivers. Is there any reason why I SHOULDN'T use the Peerless??
An externally hosted image should be here but it was not working when we last tested it.
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