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Standing in the shower thinking... (Read 8949 times)
jkalet
Ex Member



Standing in the shower thinking...
08/29/06 at 17:34:32
 
<No, not really.  That song's just running through my head, and so is this question.>

So's I'm looking at the specs for Dayton's Titanic MKIII....besides the price, why would it be an undersireable sub for a HW build?  Too much sag?  

How about using it for other decware plans?
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Adrian D.
Ex Member



Re: Standing in the shower thinking...
Reply #1 - 08/29/06 at 18:54:15
 
does it have sag ?
if you're set on the hw and the mk3 you could build it and lay it on its side.
i was dead set on the hw at first, but i ended up building the db. 2 db-12s are, imo better than a hw with 2 12s.
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jkalet
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Re: Standing in the shower thinking...
Reply #2 - 08/29/06 at 19:00:50
 
Not sure how to measure the sag, or if there's a realtionship between (magnet) mass and sag.  (Or would that be voicecoil length and sag...hmmm).  

In your opinion, 2 dbs are "better" than 1 HW, but is part of that because you have 2x the number of speakers? (assume 2 per enclosure).  How would you rate  2 dbs  vs  2  HWs?
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Adrian D.
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Re: Standing in the shower thinking...
Reply #3 - 08/29/06 at 19:08:52
 
when i read the onld db forum, i found one of steve's posts saying that 2 db-12s (1 woofer in each) would perform better than 1 hw with 2 woofers.
sag is related to moving mass (voice coil + former + cone) and suspension stiffness. post some specs, i'll see if i can help you.
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jkalet
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Re: Standing in the shower thinking...
Reply #4 - 08/29/06 at 22:02:06
 
[quote author=Adrian D.  link=1156872872/0#3 date=1156874932]...one of steve's posts saying that 2 db-12s (1 woofer in each) would perform better than 1 hw with 2 woofers. [/quote]

Wow, that's a bold statement!  I'm very surprised.  I'd like to believe this, but can anybody else verify this claim?

From PE's website regarding Titantic MKIII 15's specs:

*Power handling: 800 watts RMS/1,100 watts max *VCdia: 2-1/2" *Le: 3.84 mH *Impedance: 4 ohms *Re: 3.68 ohms *Frequency range: 19-500 Hz *Magnet weight: 136oz. *Fs: 19.93 Hz *SPL: 91.7 dB 2.83V/1m *Vas: 7.79 cu. ft. *Qms: 5.89 *Qes: .41 *Qts: .38 *Xmax: 20.5 mm *Dimensions: Overall Diameter: 15-9/16", Cutout Diameter: 14-1/16", Mounting Depth: 8-3/8".
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60ndown
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Re: Standing in the shower thinking...
Reply #5 - 08/29/06 at 23:42:22
 
[quote author=Adrian D.  link=1156872872/0#1 date=1156874055]does it have sag ?
if you're set on the hw and the mk3 you could build it and lay it on its side.
i was dead set on the hw at first, but i ended up building the db. 2 db-12s are, imo better than a hw with 2 12s. [/quote]
ive built both in a 12 inch version, i wouldnt say either is better, dbs a little cleaner, hwk has more output.
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60ndown
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Re: Standing in the shower thinking...
Reply #6 - 08/29/06 at 23:44:34
 
but my db12 had 1 x 12 inch driver and my hwk had 2?
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jkalet
Ex Member



Re: Standing in the shower thinking...
Reply #7 - 08/30/06 at 01:38:48
 
Thanks for the reply 60ndown.  I find it hard to believe that 2 db's could "best" 1 dual HWK, but who knows?  Given room placement, drivers, etc. I guess it's possible    ???


BTW am I the only one who see's a red X on the front page under Mrs. Deckert?  It's been that way since I found this decware.com and on multiple computers with different web browsers.

oh yah...back to my original question...anybody?  Bueller?
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« Last Edit: 08/30/06 at 01:39:55 by jkalet »  
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Adrian D.
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Re: Standing in the shower thinking...
Reply #8 - 08/30/06 at 06:24:42
 
60, you're experience of both is based on a car setup.
link to one of steve's posts in the old db forum.
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Adrian D.
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Re: Standing in the shower thinking...
Reply #9 - 08/30/06 at 06:27:48
 
[quote author=jkalet  link=1156872872/0#4 date=1156885326]

Wow, that's a bold statement!  I'm very surprised.  I'd like to believe this, but can anybody else verify this claim?

From PE's website regarding Titantic MKIII 15's specs:

*Power handling: 800 watts RMS/1,100 watts max *VCdia: 2-1/2" *Le: 3.84 mH *Impedance: 4 ohms *Re: 3.68 ohms *Frequency range: 19-500 Hz *Magnet weight: 136oz. *Fs: 19.93 Hz *SPL: 91.7 dB 2.83V/1m *Vas: 7.79 cu. ft. *Qms: 5.89 *Qes: .41 *Qts: .38 *Xmax: 20.5 mm *Dimensions: Overall Diameter: 15-9/16", Cutout Diameter: 14-1/16", Mounting Depth: 8-3/8".
[/quote]
specs ain't got what i need to calculate Sad
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jkalet
Ex Member



Re: Standing in the shower thinking...
Reply #10 - 08/30/06 at 14:07:03
 
I found it.  FYI for those who don't know.

http://www.partsexpress.com/resources/downfire.html

*edit*  Sorry to keep bumping my post, but according to PE's calculations, the 15" Dayton Series II (which is so popular here) has approximately 8.6% sag, while the 15" Titanic MKIII has approximately 3.05% sag.  

PE states "As a general rule of thumb, any time the sag exceeds 5% of the driver's Xmax, it's not recommended for a down-firing subwoofer application"

It looks like the Series II isn't such a good choice in a vertical HW... ???
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« Last Edit: 08/30/06 at 14:20:34 by jkalet »  
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Wreckinthehouse
Ex Member



Re: Standing in the shower thinking...
Reply #11 - 08/30/06 at 15:14:02
 
[quote author=jkalet  link=1156872872/0#4 date=1156885326]

Wow, that's a bold statement!  I'm very surprised.  I'd like to believe this, but can anybody else verify this claim?

From PE's website regarding Titantic MKIII 15's specs:

*Power handling: 800 watts RMS/1,100 watts max *VCdia: 2-1/2" *Le: 3.84 mH *Impedance: 4 ohms *Re: 3.68 ohms *Frequency range: 19-500 Hz *Magnet weight: 136oz. *Fs: 19.93 Hz *SPL: 91.7 dB 2.83V/1m *Vas: 7.79 cu. ft. *Qms: 5.89 *Qes: .41 *Qts: .38 *Xmax: 20.5 mm *Dimensions: Overall Diameter: 15-9/16", Cutout Diameter: 14-1/16", Mounting Depth: 8-3/8".
[/quote]
You would still have double the amount of woofers compared to one even if the HW was double loaded. The 2 dbs are bigger (more Volumn) and utilize the cone area of both speakers.
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jkalet
Ex Member



Re: Standing in the shower thinking...
Reply #12 - 08/30/06 at 15:23:55
 
Wreckin', I don't understand what you wrote.  Are you backing what Adrian (and Steve has) said about 2 db's being "better" than 1 dual-loaded HW?  How is a dual-loaded, magnet-to-magnet, HW not "utilizing the cone area of both speakers"?
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Lee in Arkansas
Ex Member



Re: Standing in the shower thinking...
Reply #13 - 08/30/06 at 15:28:23
 
[quote author=jkalet  link=1156872872/0#0 date=1156869272]Standing in the shower thinking... [/quote]
I do that quite often. The bathroom is one of the best places for me to think, I don't know why. When I'm really troubled by something I go to the bathroom, sit there, think about it, and the answer materializes out of nowhere it seems. Weird.....

Anyways....I remember reading somewhere that 2 single loaded db's would outperform a dual loaded hwk.
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Wreckinthehouse
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Re: Standing in the shower thinking...
Reply #14 - 08/30/06 at 16:34:35
 
[quote author=jkalet link=board=Housewrecker;num=1156872872;start=0#12 date=08/30/06 at 09:23:55]Wreckin', I don't understand what you wrote.  Are you backing what Adrian (and Steve has) said about 2 db's being "better" than 1 dual-loaded HW?  How is a dual-loaded, magnet-to-magnet, HW not "utilizing the cone area of both speakers"?[/qu                                        Think about it, the speakers are lined up back to back or front to front as the case may be. In this configuration you must wire the speakers out of phase with one another causing them to work as one. This configuration will without a boubt give you more control and tighter bass, but you will still be using the cone area of one driver 176.71 square inches. By using two single loaded cabinets you are utilizing more cone area 226.20 inches. The difference in cone area is approximately the equivalent of an 8" woofer. Pump one fist in the air you have your HW, pump 2 fists in the air you have your Db's. Get it?
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jkalet
Ex Member



Re: Standing in the shower thinking...
Reply #15 - 08/30/06 at 16:39:52
 
Yah, thanks for the example.  Now I'm thinking about why the HW is worthwhile in the first place...

*edit* (dang)
Lemme get this straight, we're still talking about filling a room (>144sqft) with bass, not a car, right?

And does anybody have any comments about driver sag/Daytons/HW/etc?
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« Last Edit: 08/30/06 at 16:47:10 by jkalet »  
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Wreckinthehouse
Ex Member



Re: Standing in the shower thinking...
Reply #16 - 08/30/06 at 17:02:41
 
I personally havn't heard the Db12's but in theory they should outperform the HW's, to a point. Remember when I said that you would have more control and tighter bass? that's where the fun starts. The db's should push more air to a certain power level and then the drivers will reach their X-max. With dual loaded HW's the opposing cones control each other. If you have the power the 2 Hw's will absolutly out perform the Db's side by side as would 2 single loaded Hw's. I use dual Peavey loaded Hw's to Dj with and they never fail to get the cops called regardless of room size. Power is the key here when comparing the output of these cabinets. I use a Peavey PV-2600 and I've got to chase these subs on the dance floor and pull them back to the stage about every 1/2 hour. The dual loaded HW is mountains away from the single loaded. The only time that I would recommend single loading a HW is for low power HT use.
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Adrian D.
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Re: Standing in the shower thinking...
Reply #17 - 08/31/06 at 05:46:25
 
[quote author=Wreckinthehouse  link=1156872872/15#16 date=1156953761]I personally havn't heard the Db12's but in theory they should outperform the HW's, to a point. Remember when I said that you would have more control and tighter bass? that's where the fun starts. The db's should push more air to a certain power level and then the drivers will reach their X-max. With dual loaded HW's the opposing cones control each other. If you have the power the 2 Hw's will absolutly out perform the Db's side by side as would 2 single loaded Hw's. I use dual Peavey loaded Hw's to Dj with and they never fail to get the cops called regardless of room size. Power is the key here when comparing the output of these cabinets. I use a Peavey PV-2600 and I've got to chase these subs on the dance floor and pull them back to the stage about every 1/2 hour. The dual loaded HW is mountains away from the single loaded. The only time that I would recommend single loading a HW is for low power HT use. [/quote]
do you have them highpassed ? check this to see some problems of the hw.
sorry to argue, but...
with the db, the drivers will be far more controlled, mainly because the sealed box behind them. even more control comes from the ported box in front.
with the hw on the other hand...
when you play freq below the tuning freq, you'll easily bottom out the drivers.
jkalet, what do you want to use the hwk for ?
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Bob in St. Louis
Ex Member



Re: Standing in the shower thinking...
Reply #18 - 08/31/06 at 12:16:09
 
Jude, (it is Jude right?  ???)
If you follow that thread, at the end, you'll find a nice HWK specifically for the LFs and below. I'm happy with what John and I have done, and will not go back. Remember this monster is for HT mainly. Slightly less musical than before but again, better to "blow things up" with.
No more 'klopping' now, even when I get stupid with it, but too boomy for music.
Somewhere in the last 5 pages or so, you'll find HZ/DB numbers after the mods.

Bob
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jkalet
Ex Member



Re: Standing in the shower thinking...
Reply #19 - 08/31/06 at 12:42:29
 
Thanks everybody.

Adrian:  It'll be for music only.  (I say "only" like there are absolutes besides death and taxes  ;) )  I plan on building something for when I DJ/spin, but I don't think I'm ready for an Imp yet.

Bob: You're correct.  Dad was a hippie ("Hey Jude") and mom was pretty religous (St. Jude).   I'm ebarrassed to say how much time I've logged combing through the posts on this site for info.  Since what I'm planning for will be for music, hopefully I won't have to do any mods.

I feel pretty confident that the HW is the right build for me; you all have been real helpful.  However, I'd be interested to hear anybody's opinion one way or the other about Dayton's Titanic line for a HW.

Jude
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Bob in St. Louis
Ex Member



Re: Standing in the shower thinking...
Reply #20 - 08/31/06 at 13:12:43
 
Jude, I feel safe in saying that if you build one of Steves designs and use a recommended/proven driver, you won't be doing any mods.  

bob
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Adrian D.
Ex Member



Re: Standing in the shower thinking...
Reply #21 - 08/31/06 at 13:57:18
 
if it's dj-ing you're after, go with the hwk.
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Wreckinthehouse
Ex Member



Re: Standing in the shower thinking...
Reply #22 - 08/31/06 at 14:04:40
 
[quote author=Adrian D.  link=1156872872/15#21 date=1157029038]if it's dj-ing you're after, go with the hwk. [/quote]
Fa Sho!!!
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gexter
Ex Member



Re: Standing in the shower thinking...
Reply #23 - 09/01/06 at 03:21:53
 
IMHO
2 single loaded DB's are better than a a dual 12 HWK.
and having two its location location location.
I have a 12 DB that sits unused because MDF is banned from the house. I was going to build a second but no longer can.
One on each side of the HT. spent way too much time on the build because I wanted them nice. I have cherry veneer that was intended for them and sits coiled up wating for a new home.
The DB 12 is nice looking and impressive. the HWK is impressive but its just a box.

Box's stand out and are great for show. IB's are stealth and sneak up on you when your not looking.
look at the attic thread. Beware that a EQ may be needed and more power is the only problem, and both can be overcome.

IMHO

Hmmm I seem to have misplaced my shower gel and the water has gone cold.
I guess I think slow.
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« Last Edit: 09/01/06 at 03:24:15 by gexter »  
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jkalet
Ex Member



Re: Standing in the shower thinking...
Reply #24 - 09/01/06 at 03:46:36
 
Interesting debate this has started.   ???  Although most of the posts have gone astray from my original question, I enjoy hearing/seeing the comparison between builds.
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Bob in St. Louis
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Re: Standing in the shower thinking...
Reply #25 - 09/01/06 at 11:05:45
 
[quote author=gexter  link=1156872872/15#23 date=1157077313]sits unused because MDF is banned from the house. [/quote]

Gex, you can't even have MDF in the house!? I thought it was the gas/dust from cuting, but you can't even have it inside!
How about painting it outside, letting it "set/seal" and bringing it inside?
Or are you being super/double/extra sure the house is CLEAN?

Bob
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Wreckinthehouse
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Re: Standing in the shower thinking...
Reply #26 - 09/01/06 at 12:38:15
 
[quote author=jkalet  link=1156872872/15#24 date=1157078796]Interesting debate this has started.   ???  Although most of the posts have gone astray from my original question, I enjoy hearing/seeing the comparison between builds. [/quote]
JKALET, Do you have the sub already? If not, why dont you use the recommended driver which is a Peavey Black widow. The cost is about the same and if you blow it you can just change the motor instead of the whole speaker
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gexter
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Re: Standing in the shower thinking...
Reply #27 - 09/01/06 at 13:07:51
 
[quote author=jkalet  link=1156872872/15#24 date=1157078796]Interesting debate this has started.   ???  Although most of the posts have gone astray from my original question, I enjoy hearing/seeing the comparison between builds. [/quote]

Whoops
sorry about that. we are not talking about thinking in a shower?
no really!  sorry about that.

On the driver ti3 I never checked the sag however it is my humble opinion that the HWK is suited to a larger Vas driver. One thing that seems to happen is the driver looses control easier in the HWK.
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« Last Edit: 09/01/06 at 13:11:54 by gexter »  
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jkalet
Ex Member



Re: Standing in the shower thinking...
Reply #28 - 09/01/06 at 13:48:33
 
Quote:
JKALET, Do you have the sub already? If not, why dont you use the recommended driver which is a Peavey Black widow.


No not yet.  I'm not THAT lazy, but it would just be easier to get all the components from the same place (ie PE) and I don't see the Black Widow on their site.  I'm not opposed to the Widow, I was just wondering about the Titanic vs the "oh-so-popular" Series II because they have similar Fs, Qts, and Vas.  One thing about the recommended Widow, Steve says it's good to around 40Hz.  Just like limbo, I'd like to go lower.  :)


Quote:
On the driver ti3 I never checked the sag however it is my humble opinion that the HWK is suited to a larger Vas driver. One thing that seems to happen is the driver looses control easier in the HWK.


Larger Vas...hmmm...good to know.  Correct me if I'm wrong but I thought I read somewhere on this board there was a misprint in the white papers.  Shouldn't it read "a maximum Vas of 10 cubic feet"?


Stay dry east coast
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Wreckinthehouse
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Re: Standing in the shower thinking...
Reply #29 - 09/01/06 at 14:52:18
 
My new parts express catalog shows Peavey speakers in stock. Check the web site to be sure. Have no fear about going low, it will definitely do that. It will go a little lower with one driver but for punchiness and shear volume and control use dual. The HW will bottom out a lot faster with one speaker. I have two deathboxes in my suv and they sound great, the only thing that I dont like is that I cant hear when the speaker is in stress With my HW's I dont have to solely rely on clip lights, because I can hear the driver struggling and back off the gain.
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gexter
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Re: Standing in the shower thinking...
Reply #30 - 09/01/06 at 15:10:17
 
[quote author=jkalet  link=1156872872/15#28 date=1157114913]

Larger Vas...hmmm...good to know.  Correct me if I'm wrong but I thought I read somewhere on this board there was a misprint in the white papers.  Shouldn't it read "a maximum Vas of 10 cubic feet"?

Stay dry east coast
[/quote]

don't quote me but I think the Titanic 3 is 1.84 which is well under that.

10 cubic feet is substantial.

Housewreaker says he backs off just a bit, you don't have to apply that to the DB, you pump a whole lot more before you have problems

This is my opinion only, not really keeping up as of late.
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« Last Edit: 09/01/06 at 15:34:34 by gexter »  
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J_Rock
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Re: Standing in the shower thinking...
Reply #31 - 09/07/06 at 06:50:42
 
2 Dbs vs. Hwk?  Hwk with same drivers will go louder, however the DBs will be punchier and cleaner, and wider band.

sag of Titanic looks fine to me- If it turns out to be a problem, just lay the sub on its side.
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jj420
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Re: Standing in the shower thinking...
Reply #32 - 09/07/06 at 16:58:51
 
OK, I didnt say anything before, but you guys seem a little confused...

The DB is a 4th order enclosure, It makes one peak at its tuning frequency.  On either side of that frequency you get a natural first order (6db/octave) rolloff.  In free air, that graphs like a camels back with one hump.  making the DB have a much more restricted bandwidth than that of the HWK (before room gain is applied).  The cone will have excellent control between the driver's Fs, and the tuning of the box, but will easy fall on its face on either side of those two specs.

The HWK is a 6th order box, it makes two peaks (sometimes 3 if the Fs of the driver lies outside the tuning of either chamber)  These peaks are bounded by a first order rolloff, just like the DB, and also have a first order rolloff into the center between the two humps because of the phasing.  This results in a much wider bandwidth than the DB (before room gain)  

Now, with only 1 driver in the HWK, it will have a wider bandwidth than the DB, but with less cone control, as there is no sealed chamber, going bonkers very easily without a strict bandpass filter bounding the tunings of the cab.  

Two or more drivers changes this story a lot though.  First, the iso loading increases the apparent volume of the enclosure, lowering tuning, the iso load also vastly improves the cone's control, since as one cone loses control below the tuning of its adjacent chamber it is bolstered by the improved control of the other driver as it appraches the tuning of its adjacent chamber.  Add to this the weight of the air between the drivers in the sealed chamber (lowers Fs of the drivers) and now you have a much wider bandwidth with considerably less distortion and a MUCH higher power handling ability.  Set up like this, the HWK and DB are two completely different animals...

As far as whats louder, 2DBs will outperform the pair of single loaded HWK, and sound cleaner too without some strong filtering.  A single HWK with 2 drivers in it will be comparable volume to a pair of DB, provided that both drivers receive the same voltage as they did in the single loaded HWKs, in addition the HWK will have extended bandwidth.  This of course assumes that everything else remains the same, which it does not.  Since the iso load of the HWK reduces efficiency, but increases handling, a significantly larger voltage could be applied across the coils in the HWK, allowing for a higher output if you have the money for the amps.

A properly loaded HWK will be just as tight and punchy as a DB, but way less efficient.

Long story short...

2dbs, more efficient, allows for dipole setup, more tuneable and runs cooler, but restricted bandwidth

1 HWK iso-loaded (mags in the middle) LOUDER LOUDER LOUDER, wider bandwidth, and cleaner too, big downside though is a massive loss in efficiency

2 HWK, single loaded, allows dipole, more efficient, wider bandwidth than DBs and runs cooler, but it takes a LOT more space and is very easy to eat drivers with

A straight up comparison of all of the variables would likely show the two boxes to be completely different animals, each suited to a more specific purpose, just like everything else audio, it depends what you need.  A DB is likely best for the car, or maybe tuned very low for HT, this is because of its simplicity and efficiency which allows for extended compromises elswhere in the system (fewer, smaller amps, fewer, simpler XO's etc.)  The HWK is a real performer though, and would likely be better for large theaters, or DJ applications, or the back of ye olde minivan for some real eye-watering fun.  The fact that the power compromise happens in the box with the iso loading allows for different compromises in the rest of the system (allows more power, resulting in a LOT more sound, as well it has a wider bandwidth, meaning that one could, depending on the build, have both midbass and bass in the same cab reducing the number of components being lugged out of the van)

In the end it is like comparing a pair of Ford Crown Vics to a single Chevy Corvette, both go fast, one is faster, both turn corners, one does so faster, both have capacity for passengers, one has room for more etc. etc. etc. it all depends on what you need.

I just had to say something, I am by no means an expert, however if you look at the basic physics involved there are some definite advantages to either deisgn, but because of the many iterations of the systems that are available it is hard to say which is better.

JJ
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Bob in St. Louis
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Re: Standing in the shower thinking...
Reply #33 - 09/07/06 at 17:42:15
 
[quote author=jj420  link=1156872872/30#32 date=1157644731]1 HWK iso-loaded (mags in the middle) [/quote]

After such an intellegent post, JJ, I'm almost embarassed to ask this; I thought iso loaded meant the drivers were "bolted together", or mounted on the same baffle, cones facing each other?  Not magnets facing each other.

Bob
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Wreckinthehouse
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Re: Standing in the shower thinking...
Reply #34 - 09/07/06 at 18:17:16
 
While they are not physically bolted together, it serves the same purpose, only difference is that there is a small air chamber between them. The reason for this is that the HW can be set up in many configurations. Whether the cones are facing each other or opposing each other makes no difference. It is recommended that the magnets be in the center chamber for the simple reason that it sounds better because the magnet structures are using up a little volume in the middle. Perhaps with other drivers that it sounds better the other way, but with my drivers it works better for me. The important factor when iso loading is to make sure that the cones are out of phase and moving in the same direction.
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« Last Edit: 09/07/06 at 18:19:18 by Wreckinthehouse »  
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J_Rock
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Re: Standing in the shower thinking...
Reply #35 - 09/07/06 at 19:21:22
 
I disagree with the hwk having a wider bandwidth.

for one, 6th order enclosure, as a rule has a very narrow bandwidth and offers very little control over the driver outside of its narrow bandwidth.  The Hwk is a little different in that it has iso loading chamber in the middle.  Still this loading changes the nature of the 6th order very little.  Its just like a normal 6th order with clamshelled drivers- except the coupling is even less strict.  If anything further decreasing the SQ of the enclosure outside of the enclosure.

The 4th order enclosure that the DB is has better transient response, wider bandwidth, and better driver control.  Basically it has the response of a sealed enclosure, with the boost of a port.  Outside the bandwidth of the port the driver is controlled by the sealed chamber.  This means the DB has more controll over the driver and a wider bandwidth.

So basically, the DBs will offer quicker(transient respone second only to sealed enclosure), more controlled bass over a wider bandwidth.

The Hwk will offer greater SPL over its more narrow bandwidth.

Of course, your observations of power handling, and efficiency are dead on.

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Adrian D.
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Re: Standing in the shower thinking...
Reply #36 - 09/07/06 at 19:54:06
 
remeber, the db and the hw aren't typical bandpasses. steve was talking in the db white papers about a varo-vent effect Wink
something similar could happen in the hw because of the placement of the lower ports.
the whole bandwidth thing is tuning related. both cabinets offer lots of tuning options.
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jj420
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Re: Standing in the shower thinking...
Reply #37 - 09/07/06 at 20:17:01
 
Bob,

actually, both apply...

Iso-loading refers to loading methods that couple two drivers to one another, so you could do like you said, and bolt the drivers together, face-to-face, or you could put the drivers at either end of a barrel with the mags inside.  I have seen set ups where the mag of one is outside the barrel, and the  and the other is sealed inside.  Converseley you could also consider two drivers on the same plane sharing a very small enclosure just big enough to allow for the excursion of the drivers used an iso-load because as one pushes, the other pulls.  

Having 2 drivers share 1 enclosure in the traditional manner also becomes a quasi-iso-load when you wire one of the drivers out of phase.  Anyone having done this will tell you thatr it destroys your output, which it does, but it also halves the Vas of the drivers.  This lowers the tuning of the enclosure considerably, but the weight of the air inside the enclosue affects the Qts of the drivers to the point that the box they share becomes completely misaligned.

Iso loading is sometimes confusing, and very easy to mess up, thats why you dont hear a lot about it.  Combined with the inefficiency of systems of this sort it is not a very appealing compromise for many applications.  Except those where power is abundant and huge output is required with low extension.

Of the various methods of iso-loading, the one you mention is the most common, as it makes the fewest compromises and has the least impact on the original T/S parameters of the drivers in use.

Jrock

I dont see how a port tuned to one frequency will have a wider bandwidth than 2 ports tuned to 2 different frequencies.  Both would share the same first order rolloff on either side of tuning.  If you tuned your DB to say, 40hz, you would be -6db at one octave above and below 40hz.  In a HWK tuned to lets say, 30 and 60hz, you would have a -6db rolloff above 60hz, and a -6db rolloff below 30hz and would be +/-3db between 30 and 60hz.  I might be looking at this wrong but +/-3db for the octave surrounding 40hz looks like less bandwidth than +/-3db from a half octave above 60hz to a half octave below 30hz.  Put it on a graph and you will see.

The SQ statement may have some merit, if the drivers used have a low BL factor, as the added mass of the air coupling them would make the cones harder to control, but with a higher BL product this would become a non-issue.

The 4th order argument works fine above the Fs of the driver, but below a drivers Fs the only way a sealed box would stop over excursion would be if it was too small to be of any use, the moveable insert of the db changes two of the parameters for the system, the first is of course the tuning of the enclosure and port (helmholtz resonator), the second variable that gets changed with this is the Q of the system.  If the Q gets too high or too low the driver cannot perform optimally, too high and the driver wont be able to push as hard as it should (good for excursion control and higher SQ, bad for output)  and if the Q gets too low then the driver will unload all over the place, regardless of tunings etc.  This is very dependent on the drivers being used, so YMMV.

I am not trying to start a fight, by all means, correct me if I am wrong, but I am fairly sure the above is correct.  Your point about faster transients is completely true however, in a properly aligned system.
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« Last Edit: 09/07/06 at 20:35:56 by jj420 »  
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jkalet
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Re: Standing in the shower thinking...
Reply #38 - 09/08/06 at 05:19:34
 
Wow!  I walk away for a few days, and BOOM a kick-a$$, informative discussion ensues.  Good stuff  :)
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Adrian D.
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Re: Standing in the shower thinking...
Reply #39 - 09/08/06 at 06:06:24
 
so, jj, it's easier to fudge up the hw when using 2 drivers ?
i tuned my db so that the sealed box is to manufacturer spec. the manufacturer also agreed on using the db  ;D
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Bob in St. Louis
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Re: Standing in the shower thinking...
Reply #40 - 09/08/06 at 10:53:22
 
Wreckin', J, and jj thanks for that explanation, and thanks for coming down to my 'level'.

Bob
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« Last Edit: 09/08/06 at 10:55:30 by Bob »  
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gexter
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Re: Standing in the shower thinking...
Reply #41 - 09/08/06 at 15:29:17
 
I didn't know the elevator went that low

jus kidding Bob could not resist. Smiley
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Bob in St. Louis
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Re: Standing in the shower thinking...
Reply #42 - 09/08/06 at 20:00:43
 
Low,... meaning, 'sub',.... you know,.... sub.
This is the Housewrecker forum after all. It's all about subs.  ;D

See, I knew I could turn a cheap shot into a positive.   Tongue

Bob Wink
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« Last Edit: 09/08/06 at 20:09:15 by Bob »  
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jj420
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Re: Standing in the shower thinking...
Reply #43 - 09/09/06 at 01:40:05
 
Adrian

thats the beauty of the DB, and its bretheren, you cant f- it up, just move that insert around till you find the right combination of port tuning and enclosure Q, they are tied to one another in this design, but it is still a wider tuning range than is available from static peices.

The HWK on the other hand, pretty much has to be retuned every time you change the number and locations of the drivers.  This makes it a tweakers dream and a marketers nightmare at the same time because it is a product that requires some forethought, as well as some knowledge to use effectively.

Not that the DB is inferior, it simply has an easier user interface, making it a very versatile solution.  As many DB users can attest, one has simply to intalll the driver and begin playback at low levels, adjusting the baffle as required.  In fact, if one were determined enough they could figure out which Q was most appropriate for each type of application, then motorize the insert and tune "on the fly" as it were.

off I go again LOL

JJ
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