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Discussion Starter · #1 ·
I plan on building a pair of 1 cubic foot sealed subwoofers' with the ScanSpeak 23W/4557T-02, 9" Aluminum Cone Subwoofer and ScanSpeak 23W/0-00-02, 9″ Subwoofer, Passive Radiator. The design goal is to build a box with as shallow a depth as possible without compromising performance. I hope to build a box with an internal depth of around 6 inches, height around 12” and whatever length is required. The build will give me the option of standing on end if placement needs change.


I would like to evenly distribute the subwoofer and passive radiator on a front panel made of ¾ inch Baltic birch glued to ¾ inch mdf, add internal Baltic birch bracing, and use ¾ inch mdf for the other sides.


Below is an email I exchanged with my dealer; My comments are blue, dealerss in green.

Shallow cabinets are always a "big" compromise in enclosures, mainly with extended bass but also with reflections returning to the rear of the driver cone.


Enclosures with their depth greater than height or width are best.


That puts a crimp in my design idea. My wife has won the Family Room design "discussion" and I was asked to remove my existing subs.
She said I could add a couple more if they were slim enough to fit behind the couch and end tables, hence my desire to build as narrow and small a box as possible.

How "big" a compromise?

How about a design just wide enough to install the drivers on the front fascia, say 10 1/2" or 11" wide leaving an internal width of 9" or 9 1/2"? I could then place them sideways behind the coach allowing the recommended depth.

These are not inexpensive so I don't want to compromise too much. If I can't fit my wife's criteria, I'll just build the optimum box and use them in another room.



Passive radiators on the same plane as the driver are the best way to go, as with a ported system, remember you are "tuning the enclosure" "not the driver".
Ports and PR's behind and interacting with the active device can yield strange results.

No problem, that is my preference.


Not sure if this applies in your design, but drivers should always be in a vertical plane, if not over a short period of time the gravity will pull the cone out of the center of the magnetic gap and then the drive will be non-linear.


I assume this will be the case, subject to your other answers.

Thank you.
 

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Discussion Starter · #3 · (Edited)
Was the one cu.ft. size recommended or did you model the driver and PR combination? Is one cu.ft. the net volume of the box?
I got 1 cubic ft. from the distributors web site but in reading it again, the 1 cubic foot is for sealed, not with passive. Glad you asked; now I realize I don't know what the internal volume should be.

"The Scan-speak 23W/4557T is a very high end subwoofer, designed to be used with a passive radiator in a small enclosure. This sub has a very rigid aluminum cone, low loss rubber surround and cast frame. The passive radiator is similar, but with a weight attached to the bass of the cone. The 23W/4557T is using the SD-1 motor system. There are gold plated binding posts and the woofer is covered by a decorative rubber cap.
Frequency response with the passive is down to 25Hz. One cubic foot sealed has an F3 of 33Hz."

Thank you.

Edit; I checked the "23W/0-00-02, 9″ Subwoofer, Passive Radiator" link and this is what is noted:

This is the passive radiator intended for use with the 23W/4557T active woofer. We recommend putting both in a 1.0 cubic foot enclosure. This should yield a bass response down to 25Hz. The woofer should still be linear at 180 watts and have an output of about 104dB.
 

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Too bad you are limited to a 6" depth, there are other driver and PR's combination that would do better for less then half the price of ScanSpeak. The ScanSpeak combination will be limited to 150 watts with a Hi-Pass filter at 18 hz, anymore than that and the PR will bottom out.
 

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Discussion Starter · #8 ·
The general rule for passive radiators is 2 PR's per sub driver. Did the manufacture say otherwise?
This is what Madisound recommends on their website;

"This is the passive radiator intended for use with the 23W/4557T active woofer. We recommend putting both in a 1.0 cubic foot enclosure. This should yield a bass response down to 25Hz. The woofer should still be linear at 180 watts and have an output of about 104dB."

Thanks.
 

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Discussion Starter · #10 ·
Too bad you are limited to a 6" depth, there are other driver and PR's combination that would do better for less then half the price of ScanSpeak. The ScanSpeak combination will be limited to 150 watts with a Hi-Pass filter at 18 hz, anymore than that and the PR will bottom out.


It’s not that I’m limited to 6”, that was just my initial preference.

As I referenced above, would a design just wide enough to install the drivers on the front fascia, say 10 1/2" or 11" wide leaving an internal width of 9" or 9 1/2" be better? I could then place them sideways behind the coach allowing the recommended depth.

I am not opposed to building the optimum box for the 23W/4557T but if I find a way to make adjustments that fit the space, better yet.

I also doubt our listening habits would cause the passive radiator to bottom out. I have a few other subs in other rooms if I want to shake the house.




 

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Discussion Starter · #11 ·
have you thought of using other shallow mount sub-woofers. I sent you an email
I have 1 ea. of the ScanSpeak 23W 9" Sub and 23W radiator already so plan on completing this build for now and will order a couple more if I am happy with the results.
Thanks for the ideas but I am respectfully asking for advice on these specific drivers and not concerned with other options at this time.

Thank you for the suggestion though.

Best regards.

George
 

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would a design just wide enough to install the drivers on the front fascia, say 10 1/2" or 11" wide leaving an internal width of 9" or 9 1/2" be better? I could then place them sideways behind the coach allowing the recommended depth.

I would personally do this compared to a shallower cabinet where the back of the driver is up against the rear wall.
 

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Discussion Starter · #13 ·

I would personally do this compared to a shallower cabinet where the back of the driver is up against the rear wall.
I agree and think that is what I will do. Here are some examples of other subs I have built.


Aurasound NS12-794-4A 12" Subwoofer - 2 cubic foot sealed



Northcreek Music Leviathan, 4 cubic foot sealed, based on 18" Aurasound if I remember right.



Aurasound NS10-513-4A 10" Subwoofer - 1 cubic foot sealed



Aurasound NS12-794-4A 12" Subwoofer - 2 cubic foot sealed


 

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Nice woodwork Snappy! And im glad to see other people taking as long as me to get started. From what I know those scan speak drivers have a great motor. The transient response should be terriffic. You could low pass that as high as 100 hz.
 

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Discussion Starter · #18 ·
Thanks, four years in storage and I was at a point to sell them or build the sub. I might have overdone the construction a little but it is a sold cabinet. While the interior dimensions are 22” x 11” x 9”, the outside dimensions are 24 x 13 x 13. Too deep to put where I had originally planned. She will probably let me put it in a back family room corner though.

I’m not quite sure which room I will end up putting it in. Most of my subs are sealed and I assume I will have the same challenges blending a PR sub with sealed subs as I would blending ported subs with sealed subs.
 
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