Help me plan my project

[jaysant1]

I am looking to build a set of speakers based on Wilson watt Puppies. I will be using (2) Seas W22NY-001 for the bass drivers. I need help to plan the dimensions for the woofer enclosure that will give me deep, accurate bass. I prefer to use a ported enclosure. For some reason I can't seem to find all the specs I need on the woofers to calculate the enclosure. If anyone has any suggestions I would be grateful.

[sreten]

Hi,

The various Puppy vent frequencies are around 28Hz to 30Hz.
The driver parameters indicate a box of 55L to 70L with 30Hz.

The response is overdamped and will need room gain to go deep.
I would be tempted to tune even lower - say 26Hz and add
some mild bass boost if room gain does not do the trick.

/sreten.

[jaysant1]

that's almost exactly what I was thinking. I was going to tune around 25-26hz in a 4.4 cubic foot enclosure. Just wanted to be sure i was heading in the right direction. Thanks for the advice.

[sreten]

Hi,

4.4 cuft ? I thinking of about half that. The air in a box is a valuable
lineariser of the suspension and thus bass distortion below 100Hz.
You want box volume per driver to be significantly lower than Vas.
I'd say 2.5 to 3.0 max cuft + possibly some EQ.

/sreten.

[jaysant1]

From all of the frequency response programs I have used they say that 4.5 cubic feet will provide the extension i'm looking for . THat being said I don't want mudd. What size enclosure do you think is optimal for quality and extension using two of the drivers i listed earlier. will 4.5 Cubic feet sound like crap? Wilson's enclosure is approximately the same size give or take. If you feel there are better drivers to use please advise me of that also. Thanks for all the advice so far.

Jason

[jaysant1]

PS there are two drivers with VAS of 75l each. I assume I am to double your guideline since i'm using two. Right? That would actually make the box smaller than VAS by .5 cubic feet. Please tell me if i'm thinking correctly my experience is limited with this type of work. The original box 4.5 cubic foot enclosure was for both drivers not one.

[sreten]

Hi,

I estimated the the internal volume of the Puppy to be < 3 cuft,
though I stand to be corrected if anyone knows any better.
(System V Puppy, assuming 1" walls, no internal bracing.)

Over 2 cuft, > 56L, per 8" driver is too big, whatever the simulations
are telling you. There are 8" drivers (not the ones in this case) that
"do" need these sort of volumes due to certain parameters, but
usually a suitable 10" would be a more ideal choice.

For vented boxes 30L to 40L per 8" driver is around the sweet spot.
Related to this ideally you want Vbox to be ~ 50% to 30% of Vas.
[< 30% Vas is too big (Qts is low), subsonic rejection will not be good.]

Vas is a small signal parameter and is anything but linear, the
suspension is nearly always progressive, i.e. it gets stiffer.

With no other problems the suspension + box volume determine
low frequency distortion. The larger you make the box the more
you allow the driver characteristics to determine distortion.

Not something modelled by a simulator ...

/sreten.

[jaysant1]

thanks. I'm going to take your advice and switch to dual 10"s in the same encosure and modify the port slightly. What do you think of Seas W26FX-001. I believe it fits right into the guideline you had given me and will still give me the bass extension I'm looking for. Thank you very much for all your help.

Nominal Impedance 8 Ohms
Recom. frequency range 20-1000 Hz
Short term max. power 400 W
Long term max. power 150 W
Sensitivity (1W/1m) 87.0 dB

Voice Coil Diameter 51 mm
Voice coil height 20 mm
Air gap height 6.0 mm
Linear coil travel (p-p) 14.0 mm
Max. coil travel (p-p) 35 mm
Magnet weight 3.0 Kg
Total weight 4.5 Kg
Voice coil resistance 6.3 Ohms
Voice coil inductance 1.43 mH
Force factor 10.7 N/A
Free air resonance 20 Hz
Moving mass 56.3 g
Suspension compliance 1.1 mm/N
Suspension mech. resistance 3.3 Ns/m
Effective piston area 330 sq. cm

Vas 161 Liters
Qms 2.28
Qes 0.41

[sreten]

Hi,

Those drivers might work better in-room sealed for 2 and 4 to 5 cuft.

Not really a Watt / Puppy clone anymore.

And very expensive bass drivers ......

What mid / treble drivers are you going to use ?

What is your target sensitivity (4 ohm) ?

Are you BSCing the mid section with the bass section - ala Watt/Puppy ?

/sreten.

[jaysant1]

focal td120 tweeter and scan speak 18w8542-00. Do you feel 4.5 cu ft it too small for those drivers. I know bass extension will suffer slightly but they should play nice and flat down to 28hz.