Best 8 inch woofer?

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acstcwrfrmn

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Joined 2014
#1
Hi guys (and gals),

I have been designing, building and testing speaker systems since the early '70's so I am quite experienced (only for personal pleasure, close friends, family, etc.).

I need a very well designed and great performing 8 inch woofer in the $150 and under range for my next project. I am retired so I think up different designs weekly; sometimes daily!

Box is to be not much larger than 1 ft^3 (28L) and closed design ONLY. This will be a true 3-way; X/O on the low end 200Hz to 400Hz. I'm planning on a 4 to 5 inch fullrange used as a mid from say 200 to well over 4KHz (maybe as high as 6KHz). The tweeter will need to be high output (> 93dB) because of my 60 year old hearing restrictions.

I'm thinking Seas Prestige has the advantage; looking for Fs 20Hz to no more than 27Hz. I have heard HiVi and Aurum Cantus specs. are WAY off! Scan discovery doesn't have any 8 inchers with this low of a Fs.

Comments? Questions? Ideas? Experiences?

This is for a small space only. Vented and TL's are too big for this space. Also, a tuned vented system at say 40Hz will not work since I often listen to pipe organ music. 16Hz on a 40Hz vented will reach X-max at less than 10 Watts. I don't expect deep bass obviously; subs. to come later. If I can get and F3 in the mid. to lower 50's thats good enough!

Thanks!
 
#3
sreten said:
Hi,

Low Fs 8"ers dedicated to sealed are hard to find.
Dayton Audio RS225-8 8" Reference Woofer
Is hard to beat. Low Fs with high Vas is pointless in 1 cuft.

rgds, sreten.
Click to expand...

OK thanks for the input. Actually, there are some 8 in. woofers with very low Fs and high Vas both BUT, the Qe and Qt ARE a very good match for a closed box. The L22 and CD22 Seas Prestige both are perfect examples of this. I don't have modeling software but I trust the Seas OEM specs. to be accurate. These are the 4 layer voice coil units (I don't have the specs. in front of me but have already checked the calculations). The Daytons have WAY too high Q's to fit the bill. Low Fs, Low Q's will work assuming the Vas is in the range of 100L to maybe 120. Check it out and do the math. These WILL work; Troels has also done some testing here as well.
 
#4
Hi,

No. The Daytons have much lower Vas than 100L to 120L.
Hence the the Fs is higher. You haven't done the maths.

Your talking complete nonsense. The Dayton I linked to
will be Qbox = < 0.7 in 1 cuft, no way is Qts WAY too high.

Your missing a vital point, the effect of the Vbox to Vas ratio
affecting the Qts to Qbox ratio and the Fs to Fbox ratio.

rgds, sreten.
 
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#6
..consider looking at a DVC woofer with good excrusion.

1 coil can integrate with your 3-way,

..the other coil can be powered with a subwoofer plate amp and can extend your lower freq. extension and even offer some opportunities for in-room eq..



I should also note the usual caveat with respect to baffle-step loss and overall efficency of the loudspeaker if it's a passive crossover design.
 
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#7
I think that people may be missing the point here. A closed box can do many things. Just as vented, TL, etc. The whole point here is to match the proven OEM TSP's to a closed box not much larger than 1 ft^3. I have about 50 designs under my belt and do know what I'm talking about. A very high Q is usually associated with a closed box while lower Q's are usually vented, etc. Any driver with BOTH high Q's and Vas BOTH will not work in a SMALLER closed box. The Daytons, HiVi, SB, etc. would require a much larger closed and/or vented box both. The goal here is to be less than $150, 8 inch and do somewhere in the mid to low 50's in a closed box that can fit in a small room. I had a design once that did 12Hz to 23KHz in a large room for under $1000. Of course, this was 20 years ago. Please; only experienced people need apply here. I am a retired Enginner; do NOT try to BS me!
 
#8
acstcwrfrmn said:
I think that people may be missing the point here. A closed box can do many things. Just as vented, TL, etc. The whole point here is to match the proven OEM TSP's to a closed box not much larger than 1 ft^3. I have about 50 designs under my belt and do know what I'm talking about. A very high Q is usually associated with a closed box while lower Q's are usually vented, etc. Any driver with BOTH high Q's and Vas BOTH will not work in a SMALLER closed box. The Daytons, HiVi, SB, etc. would require a much larger closed and/or vented box both. The goal here is to be less than $150, 8 inch and do somewhere in the mid to low 50's in a closed box that can fit in a small room. I had a design once that did 12Hz to 23KHz in a large room for under $1000. Of course, this was 20 years ago. Please; only experienced people need apply here. I am a retired Enginner; do NOT try to BS me!
Click to expand...


Don't worry about what you think it can and can't do - that's what modeler's are for. 😉
 
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#10
acstcwrfrmn said:
The Daytons have WAY too high Q's to fit the bill.
Click to expand...
No, Sreten is right, Dayton RS225-8 has ideal TS parameters for a closed box. Simple math (presuming the published TS parameters are close to truth):

Let choose Qtc=2xQts=0.76 (with stuffing will be less than 0.7)
Then, volume of the box Vb=Vas/((Qtc/Qts)^2-1) = Vas/(4-1) = 2cuf/3=2/3 cuf
When you add volume occupied by the woofer and the midrange box, it will fit in your 1 cuf box.

Edit: Sreten was quicker than me in posting.
 
#12
Hi acstcwrfrmn. I'm a retired engineer myself. It's an interesting problem to find a good closed box 8" driver, since the World and its mother has pretty much committed to reflex drivers these days. You know, big magnets an' all that, an' big boomy bass from a small box! 🙄

It's probably a bit of an ask to find a suitable closed box 8" driver these days for 30L. I quite fancy this SEAS CA22 RNX with a Qts of 0.41 and a Vas of 97L and Fs of 29Hz.

If I haven't entirely lost my touch, that equates to about 45L closed box and F3 of 55Hz.

So 30 litres is overly ambitious IMO. But you can pretty much lift the Troels Gravesen 3 way classic design on 45L closed box here. As we old engineers often say, why reinvent the wheel? 😀
 
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#16
acstcwrfrmn said:
I think that people may be missing the point here. A closed box can do many things. Just as vented, TL, etc. The whole point here is to match the proven OEM TSP's to a closed box not much larger than 1 ft^3. I have about 50 designs under my belt and do know what I'm talking about. A very high Q is usually associated with a closed box while lower Q's are usually vented, etc. Any driver with BOTH high Q's and Vas BOTH will not work in a SMALLER closed box. The Daytons, HiVi, SB, etc. would require a much larger closed and/or vented box both. The goal here is to be less than $150, 8 inch and do somewhere in the mid to low 50's in a closed box that can fit in a small room. I had a design once that did 12Hz to 23KHz in a large room for under $1000. Of course, this was 20 years ago. Please; only experienced people need apply here. I am a retired Enginner; do NOT try to BS me!
Click to expand...
People won't want to help you if you are quick to dismiss their suggestion because it doesn't fit precisely into your 'optimal ballpark' of TS parameters 🙄 TS parameters and box modeling is a multi-dimensional problem anyway - by ignoring a driver because one or two parameters are outside the range that you consider 'ideal' you could be ignoring drivers that will still accomplish what you want. The RS225-8 fits the requirements in your opening post almost exactly.
 
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#17
I just did a quick model for the RS225-8 in a 0.93 ft3 sealed box and got an F3 of ~55 Hz with the box stuffed with poly fiber at 0.5 lb/ft3. If you made the box's gross volume be 1 ft3, then the net volume should be close to what I modeled. I used Martin King's sealed-box Mathcad-based software. I also used actual T/S measurements for this driver from a personal build of a couple years ago. The RS225 certainly seems to fit the OP's requirements. The SB Acoustics 8-inch, aluminum cone woofer, SB23NACS45-8, is similar to the RS225, but should provide a bit lower F3 in the same box I modeled. BTW, OP, I'm also a retired engineer (BSEE) and have designed and built a significant number of speakers.
Paul
 
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#18
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#19
Modeling graphs

To close the loop, I've attached modeling graphs for the RS225 and SB23NAC in the same sealed box that I described in Post #17. The first graph is for the RS woofer and the second the SB woofer, both showing the predicted bass response (red line) for an input of 2.83v/1m. F3 for the RS is ~54 Hz and for the SB is ~49 Hz, with the SB woofer a bit more sensitive. Both woofers modeled using actual T/S measurements as opposed to published values.
Paul
 

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