Hi,
I salvaged a 12" woofer from my Richter Thor IV sub (I had it in storage and the MDF became a sponge in a puddle), the manufacturer has no specs on the woofer and I see zero markings on it, apparently it has 32mm usable excursion. I measured it at 4 ohms.
I'm going to run it with a DSP and I've got a Emotiva (XPA-100) 400W (4 ohm) mono amp spare that I might use to drive it (the plate amp on the sub failed prior to it going into storage).
Would you use it, its in nice condition, are they expensive, if it's only worth say $50 it might be worth getting something new?
I don't really have the space anymore for a large cube like the original box, I assume it's OK to build a flatter rectangle with the same volume?
Just mentioning I do have a couple of 10" DS270-PR but with an 11mm XMax I'm pretty sure this isn't a use for them.
Thanks.
Richard
I salvaged a 12" woofer from my Richter Thor IV sub (I had it in storage and the MDF became a sponge in a puddle), the manufacturer has no specs on the woofer and I see zero markings on it, apparently it has 32mm usable excursion. I measured it at 4 ohms.
I'm going to run it with a DSP and I've got a Emotiva (XPA-100) 400W (4 ohm) mono amp spare that I might use to drive it (the plate amp on the sub failed prior to it going into storage).
Would you use it, its in nice condition, are they expensive, if it's only worth say $50 it might be worth getting something new?
I don't really have the space anymore for a large cube like the original box, I assume it's OK to build a flatter rectangle with the same volume?
Just mentioning I do have a couple of 10" DS270-PR but with an 11mm XMax I'm pretty sure this isn't a use for them.
Thanks.
Richard
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Absolutely I'd use it. In my experience (on here), the majority diy'ers will dismiss perfectly good drivers because they don't have the T/S parameters, therefore cannot simulate the performance via their beloved WinISD.
1) A subwoofer has 3 significant components. (i) Driver (ii) Cabinet (iii) Port.
2) Accept the fact that the highly paid engineers at Thor are more likely to know what they're doing that a bunch of amateurs using free software.
3) Reverse engineer to understand the original cabinet volume & original port tuning.
4) The loss of the plate amp will give you 1 - 5 litres more volume.
5) In this instance, the driver parameters fixed. Once you have a firm cabinet design - the volume is fixed. The port is your only available variable.
1) A subwoofer has 3 significant components. (i) Driver (ii) Cabinet (iii) Port.
2) Accept the fact that the highly paid engineers at Thor are more likely to know what they're doing that a bunch of amateurs using free software.
3) Reverse engineer to understand the original cabinet volume & original port tuning.
4) The loss of the plate amp will give you 1 - 5 litres more volume.
5) In this instance, the driver parameters fixed. Once you have a firm cabinet design - the volume is fixed. The port is your only available variable.
I agree.
But then again the highly paid engineers at Thor must design a subwoofer that sells and makes a big first impression in the shop and they might do that very efficiently.
a bunch of amateurs can optimize the response to have less "first sight effect" and be more adapted to an actual room.
just my 2 cents.
This is true. However, their design will get '000s of opinions and reviews - yours will get just one. And the port is the final and cheapest variable.
Hi,
I found this shallow sub link which is what I'm thinking, I'm planning on something like 750x500x230mm (WHD) internal which will give 86L, which is going to be pretty close to the original. The woofer will be firing out of the front 750x500mm face, centred.
So the question is porting, the link mentions a labyrinth design (the bracing it gives sounds like a great idea), should I go with that, if so, would I do horizontal or vertical labyrinth walls, horizontal would be easier, require less material and eat up less litres, if a horizontal labyrinth is cool, would you just do one "port" or two (basically one labyrinth to the left of the speaker and one to the right, with the added bonus of bracing at both sides)?
Thanks.
Richard
I found this shallow sub link which is what I'm thinking, I'm planning on something like 750x500x230mm (WHD) internal which will give 86L, which is going to be pretty close to the original. The woofer will be firing out of the front 750x500mm face, centred.
So the question is porting, the link mentions a labyrinth design (the bracing it gives sounds like a great idea), should I go with that, if so, would I do horizontal or vertical labyrinth walls, horizontal would be easier, require less material and eat up less litres, if a horizontal labyrinth is cool, would you just do one "port" or two (basically one labyrinth to the left of the speaker and one to the right, with the added bonus of bracing at both sides)?
Thanks.
Richard
Thanks, I'm a bit of a newbie, what exactly does the DSP give me, it allows me to perform the boost in bass I would get with the bass reflex in software?
Could I make the box a little bit smaller say 10-20% less volume?
Could I make the box a little bit smaller say 10-20% less volume?
DSP allows you to adjust the response to whatever you would like it to be.
That said, a 3 dB boost is same difference as 200 to 400 watts.
The Thor MR4 amp was rated for 200watts, the speaker has only a 50mm (2") voice coil, not made for high power.
That said, if the speaker reads 4 ohms DCR, it's probably ~6 ohms in the cabinet, your XPA-100 output will be somewhere between 250-400 watts when it clips.
The bass reflex ports put out most of the enclosure's output around their tuning frequency, while reducing the excursion of the driver around Fb (frequency of box tuning). The ports allow the cabinet to put out considerably more output around Fb than a sealed cabinet, but less below, as the port and speaker output become out of phase just below Fb.
A steep HP filter should be engaged below Fb to prevent over-excursion.
If you see more than 32mm (~1.25 inch) peak to peak, the driver has exceeded it's "usable excursion".
You could, but the ports would need to be made longer to have the same Fb as in the original cabinet, and their output would be reduced. Since you want to make a shallow cabinet, the ports may need to be positioned differently, exiting on the side, or folded to fit.
The Thor MR4 ports are already undersized for the excursion the driver has, but larger ports would need to be longer, further reducing the cabinet volume.
Art