I currently have an Usher 2 way with the 8945 woofers and 9950 tweeters
The Plan
The plan is to make 2 boxes with two Usher 8955 in each box. These would serve as stands for the bookshelves. ala Wilson watt /Puppy config. . The Usher 8955 came to mind as this would be the closest matching driver to my current woofer and being similar in size and construction wont lag behind the 8945 mid/woofer. I plan to operate the sub from 25 to about 40 HZ
any thoughts on this ?
The Plan
The plan is to make 2 boxes with two Usher 8955 in each box. These would serve as stands for the bookshelves. ala Wilson watt /Puppy config. . The Usher 8955 came to mind as this would be the closest matching driver to my current woofer and being similar in size and construction wont lag behind the 8945 mid/woofer. I plan to operate the sub from 25 to about 40 HZ
any thoughts on this ?
Thats more of a bass driver than a sub driver - how far up do you intend on using them? If its beyond 100hz then stick with them, if it is for sub duty only (20-50hz) then I would pick the Dayton RS 10 or 12" - you could go side-fired if you want to keep cabinet wodth down.
Hi guy,
I’ve designed a lot of similar systems with the corresponding Scan Speak elements and think if I had used the Usher’s, they would have very similar performances and qualities.
You’ve made a very good choice to extend the 8945’s as you seem to aiming at a very low distortion system, but are you aware of the seize that this would mean if designing for 25 Hz?
Do you have T/S data for the specific 8955’s you have or will buy? What about the sub-amp specifications you surely need for crossing over at 40 Hz.
The ability to interface without adding artefacts from the definition of the low-end side to will be crucial for this application i.e. the sub amp, in this case, bandwidth definition must reach very low frequencies and without any low end filtering higher than first order and about 10 Hz.
For me its look like you are trying to crossover a ported 8945 at 40 Hz without considering the very mess and footprint this would imply to the summation by destroying the possible low-end definition and fidelity.
Another way to circumvent this possible sonic disaster, is by choosing a cutover higher than 80 Hz, preferably at 100 or even higher, if a ported box, or close the mid-woofer ports and eventually adjust the volume to suit a transfer function that integrates smoothly with the sub amp LP filter and so on.
b
I’ve designed a lot of similar systems with the corresponding Scan Speak elements and think if I had used the Usher’s, they would have very similar performances and qualities.
You’ve made a very good choice to extend the 8945’s as you seem to aiming at a very low distortion system, but are you aware of the seize that this would mean if designing for 25 Hz?
Do you have T/S data for the specific 8955’s you have or will buy? What about the sub-amp specifications you surely need for crossing over at 40 Hz.
The ability to interface without adding artefacts from the definition of the low-end side to will be crucial for this application i.e. the sub amp, in this case, bandwidth definition must reach very low frequencies and without any low end filtering higher than first order and about 10 Hz.
For me its look like you are trying to crossover a ported 8945 at 40 Hz without considering the very mess and footprint this would imply to the summation by destroying the possible low-end definition and fidelity.
Another way to circumvent this possible sonic disaster, is by choosing a cutover higher than 80 Hz, preferably at 100 or even higher, if a ported box, or close the mid-woofer ports and eventually adjust the volume to suit a transfer function that integrates smoothly with the sub amp LP filter and so on.
b
Yes check the specs, for a box volume of 1.9cu.ft. you are looking at an F3 of 39hz - this driver will not do 25hz.
http://www.partsexpress.com/resources/indexes/sb_guide.cfm
http://www.partsexpress.com/resources/indexes/sb_guide.cfm
The specs for the 8955 woofer is
Specifications: *Power handling: 80 watts RMS/90 watts max *VCdia: 1-5/8" *Le: .50 mH *Impedance: 8 ohms *Re: 5.7 ohms *Frequency range: 25-7,000 Hz *Fs: 25 Hz *SPL: 87 dB 2.83V/1m *Vas: 4.70 cu. ft. *Qms: 2.00 *Qes: .38 *Qts: .32 *Xmax: 6.0mm
I was thinking of a woofer stand that would be 24 tall and about 9 inches across and X inches deep ?
How big a box do I need for one 8955 when going for 25 or say 30 hz ?
Specifications: *Power handling: 80 watts RMS/90 watts max *VCdia: 1-5/8" *Le: .50 mH *Impedance: 8 ohms *Re: 5.7 ohms *Frequency range: 25-7,000 Hz *Fs: 25 Hz *SPL: 87 dB 2.83V/1m *Vas: 4.70 cu. ft. *Qms: 2.00 *Qes: .38 *Qts: .32 *Xmax: 6.0mm
I was thinking of a woofer stand that would be 24 tall and about 9 inches across and X inches deep ?
How big a box do I need for one 8955 when going for 25 or say 30 hz ?
Check the link to partsexpress gives you a quick idea of optimum volumes.
Otherwise if you model with WinISD (its free) I come up with 2.2cu. ft (thats 24hx9wx24d) tuned to 30hz, gives an f3 about 35hz - but efficiency is going tio be quite low - I doubt you can stretch this driver (or any 8") to much below 35hz.
Otherwise if you model with WinISD (its free) I come up with 2.2cu. ft (thats 24hx9wx24d) tuned to 30hz, gives an f3 about 35hz - but efficiency is going tio be quite low - I doubt you can stretch this driver (or any 8") to much below 35hz.
Thinking some more - if you are going for a single driver, then why not check out Aurum Cantus AC-250F1 10",
2.4cu.f t gets you down to 31hz plus it is 90db efficiency and 7ohms, plus a little cheaper than the usher too.
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=296-430
2.4cu.f t gets you down to 31hz plus it is 90db efficiency and 7ohms, plus a little cheaper than the usher too.
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=296-430
Right now I'd say you are in "no man's land" with what you have in mind. IMO best to stick to either:
1. subwoofer with a true sub driver with the upper bandwidth determined by placement and the performance of the driver (most subs perform poorly above 40 Hz)
2. stereo woofers crossing between 80 - 300 Hz with a lighter driver with smooth midrange, low inductance, a good linear motor and decent xmax
What you are doing is crossing low and operating in the range where a true sub driver will perform adequately and give you greater headroom and depth, yet you are using a woofer and in two boxes which could actually cross up higher very easily and improve the performance of your mains.
Some of the better subs can actually happily go up to 80 or even 100 Hz.
So, my suggestion is either make it a sub, or consider crossing your woofer higher. The simplest solution is run your mains full range and just add in a single sub.
As far as musical subs go, Rythmik Direct Servo is definately worth considering.
1. subwoofer with a true sub driver with the upper bandwidth determined by placement and the performance of the driver (most subs perform poorly above 40 Hz)
2. stereo woofers crossing between 80 - 300 Hz with a lighter driver with smooth midrange, low inductance, a good linear motor and decent xmax
What you are doing is crossing low and operating in the range where a true sub driver will perform adequately and give you greater headroom and depth, yet you are using a woofer and in two boxes which could actually cross up higher very easily and improve the performance of your mains.
Some of the better subs can actually happily go up to 80 or even 100 Hz.
So, my suggestion is either make it a sub, or consider crossing your woofer higher. The simplest solution is run your mains full range and just add in a single sub.
As far as musical subs go, Rythmik Direct Servo is definately worth considering.
qguy,
Between 63 to 83L seem right if you chose o build a MLTL/MLTQWT and I believe the 9” width (f-3dB 25 Hz) is not as good as 12” (f-3dB 25 Hz), which has a shorter port (less ringing).The Zalytron closeout sale is each for $ 80, maybe you can afford to build 4 speakers and gain about +6 dB?
b
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