wilson audio :watch dog subwoofer drivers

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hi everyone;
jut got a hand on a pair of these :http://www.soundstage.com/revequip/wilson_watchdog.htm
its has rms of 400w ultra linear motion with dual spide triple stacked huge huge huge triple stacked motor .


the original design is ported....without T/s information i want to go sealed with some good class A/B amplifier instead of d switiching.


what how could i put best SQ use?
 
Most commercial speakers and subwoofers are compromised in some way - the designer has had to accept less than ideal driver quality and parameters, enclosure quality and amp quality. There is scope for DIY to correct these compromises.

The Watchdog does not have these problems. It is already designed for "best SQ use". It is a music sub, not a HT sub. It is not compromised by having to be designed down to a price point - the driver, enclosure and amp have been specifically custom built to work well together. For example, the class D amp will almost certainly be sonically indistinguishable from a class AB amp. The designer would have used Class AB if it would sound better in this application.

As for the driver, its parameters have been chosen to work best in the given enclosure. If you lack the tools and expertise to measure the driver T/S parameters and determine if it will work well in a sealed enclosure, I suggest you leave it as it is. Otherwise, you will almost certainly make it sound worse.
 
I second exactly what Don has said. The Watchdog product has been done as a cost no object item and unless the designer had some seriously flawed ideas as to what that entailed then it would probably be best to leave it well alone.

The amplifier and it's internal active filtering has probably been tailored to match the drive unit and cabinet so that the two will work well together. In other words the amplifier is matched to the drivers capabilities within the cabinet so that damage wont occur, but will also not limit the performance. I would expect this kind of thing in a cost no object design, 400 watts might seen like small fry when compared to the kilowatt class Ds found in the small sealed subs, but if making it any bigger would have improved performance you can bet that it would have been.

I would recommend you use the sub as is for now and see how you like it. If you find yourself disliking it for whatever reason then maybe post here and suggestions can be made as what to do next.

Regardless of the cost, the Watchdog it is still at the mercy of room acoustics, it cannot break the laws of physics either, so there is a limitation as to what it can achieve. Audio nirvana is most likely an unobtainable goal, so just because it is expensive don't expect it to do things that it realistically cannot.
 
no doubts about the above observations. but the problem is that i have drivers NOT the woofers........ what could i DIY with them without their T/s and cabinet design.....can i go sealed and increase power with equiization//

btw i am currently running 802 b&w with krell fpb 600 ..goes fairly good down to 50 hz...what to to?
 
i have drivers NOT the woofers........

Yes the problem with that statement is that drivers and woofers are the same thing. So you said I have the apples, not the apples. Hence the confusion.

If you own the drivers but no cabinet then you really could do with finding out what specs it has. Measuring for the T/S parameters isn't that hard. Even a simple free air impedance measurement will give you the drivers Qts and Resonance frequency.
 
Push-push like that is a commendable approach, however I reckon you'd get better results if you went for push-pull. Ie the driver on the front of the cabinet is mounted with its cone to the world, but the driver on the back of the cabinet is mounted with its magnet to the world.

With regards to going ported or sealed, it largely depends on the driver specification. Most sub drivers will easily work in sealed and ported enclosures, the trouble is what the designs entail.

When the driver is put in a ported cabinet and tuned low. Like this you tend to get flat results down to around 20-25hz, so it needs very little in the way of equalisation and thus very little (relatively) power to do its job.

When sealed, the cabinet is naturally made quite a bit smaller, how small depends on the rest of the design parameters. But this obviously means the driver wont go as low as in the ported version. This requires EQ if you're going to end up with extension down to 20hz. This in turn requires a LOT of amplifier power. As an example the Watchdog has a 400 watt amplifier, but the Krell jobby needs 2600 watts.

Measure the T/S parameters of the Watchdog driver and then simulate to see what it will do. Then make the cabinet as large as you can live with and go from there. You might find you are also better off building two subs rather then one.
 
agreed. but my worry is that its only a 400 w rms driver which takes advantage of some equilization and superb ported design...... well should i take the diy route (with live dsp equalization) as i want to go sealed and use dsp . i am asking this because its a 12 inch driver and very expensive whereas i can get 15 inch b&W 1000w driver used for sealed cabinet in asw 855 for half the price.
15 inch and 1000 watts seems more spl but i am not sure about sound quality, any guess which would sound better ? btw wilson drivers have almost same magnet motor but double spider.

regards
 
I think you're right to be concerned, will the driver be capable of handling the extra power as would be necessary from using a sealed cabinet?

The only way to know is to measure the T/S parameters and see just how much power you'd need to give it to arrive at your SPL requirements.
 
agreeed. wil start with measuring t/s and then will seek your guidance through discussion and project pics.
BUT just an ignorant question.......i have the option of a pair of 15 inch 1000w rms capable drivers for b&W asw 855 ....its sealed with known dimensions....and half the price for wilsons.......the wilsons have a bit better motor structure and dual spider for mor linearity and reportely 3 inch xmax which i wonder if possible with 400 watts. any way just to get input......which driver could be better for bass extension with true SQ. regards
 
As I got it the idea in the WA watch dog construction was to make a "real" bass system which could go all the way down only with acoustic reinforcement from the reflex port hence getting a much more sensitive system than the typical large heavy driver in smallish enclosure and then boost the bass.

The reason for this approach was as I remember to avoid the dynamic compression related to the increased power of boosting, which unavoidely turnes into extra heat in the coil of the driver(s (woofer and amp). Deviating from this approach will NOT get the same results, even if more power is added.

Use about 140L per driver in a heavily reinforced cabinet and then tune the port to your liking (probably around 18-23Hz). Give it a proper amp like the SKA or Aussie amp (other suggestion may be equally as good...) if you stick with the class AB approach, but a good class D design should also be able to do it. The slight less damping factor of class AB may increase the Qt of the driver hence affecting the system Q so it might be a good idea not to deviate too much here as well. All amps sound different though so choosing class AB alone may not cut it, but some port tweaking will probably get you there :) The possible equalization in the WA Dog is probably to handle specific room modes which relates to the dimension of the room, placement of sub, and several other things...

If you want a smaller sub, a compound design featuring two woofers should be able to do the same in a 70L cabinet (theoretically) with the same SPL but half the impedance (you may need two identical amps if the drivers are 4ohms). Also the port should be longer due to the smaller cabinet, which may be a consideration too...

Does any one know where WA sources these woofers?

cheers
 
well thanks juhleren , 5th element and all others. really appreciate the input. now we are starting to have some good starting point. i think wilson would made real good music subs and i would go with some real good a/b amp with them. b&w i think would be better for HT. so lets begin with the wilson audio , i got these drivers from a local wilson dealer who stored these as oem replacements just in case but never had to sell them as no one ever burned the pair of watch dog he sold:)

now 140 L is around 5 cubic feet which i feel is pretty good enough size for a 12 inch ported sub. so i was wondering ;;;;could i use compound like this >: :< magnet to magnet in the box... ?please advice because if we fail in ported design its a failure with a sealed system i would have the option of using them from 100-40 range and using b&W 15 inch drivers from 40 and below....just a raw idea.

btw i read somewhere it has Xmax of 3 inch ! its too huge a driver will post pictures soon.
 
Woofer:
One - 12 inch Dual Spider (30.48 cm)Sensitivity:83 dB @ 1 watt @ 1m @ 100 HzNominal Impedance:8 ohms/minimum 5.6 ohms @ 1 HzMinimum Amplifier Power:200 Watts (for theater applications)Frequency Response:15Hz - 300Hz Room Average ResponseOverall Dimensions:Height w/ spikes – 26.875 inches (68.26 cm),
Width – 18 inches (45.72 cm),
Depth – 25.125 inches (63.82 cm)Weight:211 lbs (95.7 kg)Total Shipping Weight (approx):281 lbs (127.5 kg)
 
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