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HWK 15 Driver selection (Read 3520 times)
Jerry_Allen
Ex Member



HWK 15 Driver selection
11/01/05 at 22:01:14
 
After building a HWK-12 out of scraps and non-desirables... (it looks bad)

I am going to build the HWK-15.  Reading the HWK white paper;

"For the 15" version ideal woofer selection if you going for low bass would be a subwoofer with an fs around 20 Hz, and a Qts less than .38 and a minimum VAS of 10 cubic feet."

I find the DAYTON DC380-8 15" CLASSIC WOOFER with specs 8 ohms Fs: 20 Hz SPL: 92.8 dB Vas: 14.00 cu. ft. Qts: .30 Xmax: 4.3mm. The DC380-8 15 ($47.00) is not a subwoofer yet has better closely matched parameters to the HWK white paper than the DAYTON QT385-4 15 subwoofer ($86.00).  DAYTON QT385 Specs 4 ohms Fs: 21 Hz SPL: 91.8 dB Vas: 6.60 cu. ft. Qts: .41 Xmax: 10 mm

Granted the DC380 does not have the power capability of the QT385 it is a cheaper driver, has 1 db higher spl and the lower xmax should help to limit the port noise.

Can low bass be made without large cone movements? Which is better, DC380 or QT385?
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gexter
Ex Member



Re: HWK 15 Driver selection
Reply #1 - 11/02/05 at 00:25:50
 
To my knowledge and don't quote me .  
Don't worry about the X max.  Its over rated
I would go with the one with the classic woofer.
because of the Vas and the Fs is so close that the low extention is darn close.

Low bass can be made just fine without large cone movements.
the enclosure and location are more important.

Gex

where are all the smart guys, this fella could use a hand
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toomanyamps
Ex Member



Re: HWK 15 Driver selection
Reply #2 - 11/02/05 at 01:37:09
 
I used the the Dayton Series II ST385-8  (about $88 ) and the measurements were also very close. fs 19 qts .34  Vas 9.64  Xmax 8mm
I just found that they did not work well in the HWK-15 cabinet. I cut mine in half and made two ported 4 cu.ft. cabs that work better in my room. Maybe the lighter cones will work better for you. I would recommend against the driver I chose. Embarrassed
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« Last Edit: 11/02/05 at 01:39:47 by toomanyamps »  
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Jerry_Allen
Ex Member



Re: HWK 15 Driver selection
Reply #3 - 11/02/05 at 02:24:52
 
toomanyamps,

I may have success, if not the new drivers will become a replacement set for my main speakers which are about 15 years old now.

I have read most of your posts concerning your HWK, not sure what sound you are after but you mention low response in the teens so here goes... I use mine for home theater and listen to Pink Floyd/Blueman/Enigma and acoustic symphony music, that is what I built my system for. I am not sure if you are electronicly inclined, I found a device that when you understand how it works and build it for your room and your tastes you can model the bass to what you want given the speaker can stand the SPL at the boosted ranges... http://sound.westhost.com/linkwitz-transform.htm. My experience has been nothing but positive on this device. My new HWK-12 is running on the device after listening with or without it inline there is no question which is better for me and my HWK-12 is running with 2 "lightning Audio" drivers from Walmart, they are very cheap, bad parameter drivers. If you want low bass, this is a way to get it, my HWK-12 had way to much punch, I took off the puch by changing the lower port size and length and put 12db in from 10hz to 30hz. The linkwitz board is cheap and the parts are cheap, however if you are not inclined to electronics you will have a difficult time as the caps and resistors are all custom requiring series/parallel combinations to get the values you need. In the end I have built 4 of these for various applications and have clean clear bass in my 13' x 17' x 7' room that does not rumble the whole house, especially with the HWK-12, the room has some odd characteristics that cancel the bass in room but the house rocks, adding the HWK-12 to the back wall changed the room now the room will rock without the house.


[quote author=toomanyamps  link=1130886074/0#2 date=1130895429]I used the the Dayton Series II ST385-8  (about $88 ) and the measurements were also very close. fs 19 qts .34  Vas 9.64  Xmax 8mm
I just found that they did not work well in the HWK-15 cabinet. I cut mine in half and made two ported 4 cu.ft. cabs that work better in my room. Maybe the lighter cones will work better for you. I would recommend against the driver I chose. Embarrassed [/quote]

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Jerry_Allen
Ex Member



Re: HWK 15 Driver selection
Reply #4 - 11/02/05 at 02:26:37
 
Gex,

Thanks for the input... I bought the classic woofer. Next comes the MDF Smiley

Jerry

[quote author=gexter  link=1130886074/0#1 date=1130891150]To my knowledge and don't quote me .  
Don't worry about the X max.  Its over rated
I would go with the one with the classic woofer.
because of the Vas and the Fs is so close that the low extention is darn close.

Low bass can be made just fine without large cone movements.
the enclosure and location are more important.

Gex

where are all the smart guys, this fella could use a hand
  [/quote]
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gexter
Ex Member



Re: HWK 15 Driver selection
Reply #5 - 11/02/05 at 05:01:42
 
I was hoping that someone would chip in and agree or disagree on my concepts, before you bought them.

It would be my choice in the two. but there could be other choices.

Gex
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Jerry_Allen
Ex Member



Re: HWK 15 Driver selection
Reply #6 - 11/02/05 at 13:09:01
 
gex,
If you are wrong, I have a use for them so I am not real concerned, bass is an experiment....

Update and a probable oops...
http://www.decware.com/cgi-bin/yabb/YaBB.cgi?board=Housewrecker;action=display;n...
Speaking of the quoted parameters...
" That's a typo on the site, that was discussed before but never fixed.  It should read max Vas 10ft.  When you clamshell drivers the Vas is cut in half.  The top and bottom isobarik alignment reduced vas some but not by half due to the large air cushion. "


[quote author=gexter  link=1130886074/0#5 date=1130907702]I was hoping that someone would chip in and agree or disagree on my concepts, before you bought them.

It would be my choice in the two. but there could be other choices.

Gex [/quote]
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« Last Edit: 11/02/05 at 14:03:14 by Jerry_Allen »  
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toomanyamps
Ex Member



Re: HWK 15 Driver selection
Reply #7 - 11/08/05 at 04:35:01
 
Jerry, funny thing, I was spending way too much time trying to figure out how BAG END was claiming flat response to 8 hz with a sealed (and not very special looking 2x12 cab). I was doing this yesterday and followed your link today and TAADAA..  common element... Linkwitz-transform. Wink The whole EAS thing looks interesting. I'm going to look into building a board for my projects. Yes - I'm electronics minded nowbut not single, childless or free enough to do it all hours either Roll Eyes

Like you I consider this an experiment. I sold my hi-buck M&K to be able to go BOOM Boom in my room if I want. This I have now done-- in spades Cheesy I also spent about 20% of what the M&K sold for. No upgrade path for me. Build and build again..

My problems with my Dayton were echoed by JohnF. In some of his posts and a few PM's he sent me. I'm impressed with the Daytons in general and would buy another set. I'm building a WO32 and am eyeing the dayton II 10's. Grin


Some of the problems I had with the HWK 15 were a terrible steep rolloff below 40 hz and severe cancellation around 57 hz ( I'm guessing between the two chambers). I tried all possible combinations and used the placement principle to exite the minimum amount of room modes.

My boxes are now cut in half, double braced stupidly rigid and have double thick end caps. They have 4 inch ports facing the side. They sound pretty good. They go down to about 24 hz with good output but things could be better. I'm using a Behringer Ultracurve to try to flatten out the freq. response but I really need to stuff the ports and go sealed again. The group delay just stinks. Takes a long while to establish a wave.

The Imperial SO looks cool but like I said... I'm not single... and I don't want to be..  ;D
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Jerry_Allen
Ex Member



Re: HWK 15 Driver selection
Reply #8 - 11/09/05 at 02:51:50
 
[quote author=toomanyamps  link=1130886074/0#7 date=1131424501]Some of the problems I had with the HWK 15 were a terrible steep rolloff below 40 hz and severe cancellation around 57 hz ( I'm guessing between the two chambers). I tried all possible combinations and used the placement principle to exite the minimum amount of room modes. [/quote]

Looking at my HWK-15 model in Win Isd, I BET I have the same 57 Hz problem. The Phase is 180 degrees out at 57 Hz. As far as roll-off, last Friday I was "testing" the new HWK-12, after some Pink Floyd (the heart beat), my 15 year old came down and asked if I could turn it down...  :-/ ... paybacks are not a ***!

The HWK-12 I built models virtualy the same, I would stick with it if I had built it as a piece of furniture instead of a garage masterpiece. That's the only reason I am building the HWK-15. New wood, new drivers, 1/4 round edges, black paint, looks _real_ nice, fingers crossed for the sound but I LIKE the experiment!
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gexter
Ex Member



Re: HWK 15 Driver selection
Reply #9 - 11/11/05 at 06:18:25
 
Jerry_Allen
On the 12 HWK you built. How did you end up placing your speakers in the box, I am assuming you used two drivers.

Did you look at changing port size to overcome the 57Hz problem you guys are speaking of.
I would like to know if you have tried to find a solution.
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Jerry_Allen
Ex Member



Re: HWK 15 Driver selection
Reply #10 - 11/11/05 at 14:23:19
 
[quote author=gexter  link=1130886074/0#9 date=1131689905] Jerry_Allen
On the 12 HWK you built. How did you end up placing your speakers in the box, I am assuming you used two drivers.

Did you look at changing port size to overcome the 57Hz problem you guys are speaking of.
I would like to know if you have tried to find a solution. [/quote]

I loaded the 12"s magnet to magnet in the center chamber. As far as the ports are concerned I do not see that port size or length make any change in WinISD in either phase or group delay, I am guessing that bandpass has this shortcoming or WinISD does not work correctly, again just guessing.

I built the 15 much better (t nuts for the drivers and 1/4 x 20 endcap bolts with threaded inserts) so changing the driver position and wiring phase will be much easier to accomplish without risk of stripping out a wood screw. I should be able to sound test this weekend.

Jerry
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