Welcome, Guest. Please Login or Register
Decware Audio Forums
11/29/14 at 08:48:03


Pages: 1 2 3 
Send Topic Print
Standing in the shower thinking... (Read 8865 times)
gexter
Ex Member



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.
Back to top
 
« Last Edit: 09/01/06 at 15:34:34 by gexter »  
  IP Logged
J_Rock
Ex Member



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.
Back to top
 
 
  IP Logged
jj420
Ex Member



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
Back to top
 
 
  IP Logged
Bob in St. Louis
Ex Member



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
Back to top
 
 
  IP Logged
Wreckinthehouse
Ex Member



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.
Back to top
 
« Last Edit: 09/07/06 at 18:19:18 by Wreckinthehouse »  
  IP Logged
J_Rock
Ex Member



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.

Back to top
 
 
  IP Logged
Adrian D.
Ex Member



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.
Back to top
 
 
  IP Logged
jj420
Ex Member



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.
Back to top
 
« Last Edit: 09/07/06 at 20:35:56 by jj420 »  
  IP Logged
jkalet
Ex Member



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  :)
Back to top
 
 
  IP Logged
Adrian D.
Ex Member



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
Back to top
 
 
  IP Logged
Bob in St. Louis
Ex Member



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
Back to top
 
« Last Edit: 09/08/06 at 10:55:30 by Bob »  
  IP Logged
gexter
Ex Member



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
Back to top
 
 
  IP Logged
Bob in St. Louis
Ex Member



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
Back to top
 
« Last Edit: 09/08/06 at 20:09:15 by Bob »  
  IP Logged
jj420
Ex Member



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
Back to top
 
 
  IP Logged
Pages: 1 2 3 
Send Topic Print