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hz numbers on a 15" 2 driver (Read 38732 times)
John in CR
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #120 - 05/19/06 at 01:42:20
 
J_Rock,

You haven't been reading very closely.  Bob's HWK has been converted to a low tuned BR using only minor changes and NOT having to build a whole new box.  I did some quick and dirty modelling for him and using the center and bottom chambers as his Vb, he could tune pretty low using isobarik loading.  Now he's going to measure what he has, to figure out where he wants to go.

If his mains reached down to 40hz, then the HWKenstein would be the most compact way to get prodigous output down in the low teens.  The alternative is 2 big (350L+) BR boxes, if the isobarik BR doesn't have enough output.  About the only thing that hasn't been discussed is a rumble filter to protect his drivers from over-excursion.  Before getting into that, I was just going to let him run some tests with a longer port.
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J_Rock
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #121 - 05/19/06 at 02:45:11
 
I understand that much, I am suggesting that he DOES start over.  

Of course after testing the HWKenstien.

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John in CR
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #122 - 05/19/06 at 03:13:38
 
[quote author=J_Rock  link=1145573673/120#122 date=1148003111]I understand that much, I am suggesting that he DOES start over.  

Of course after testing the HWKenstien.
[/quote]

He can't really use HWKenstein, even though I'd like to hear about it too.  The thing is, he already has a finished 200+L solid cab.  Using the 150+L of the bottom 2 chambers of his HWK may work until he builds new mains.  The 6th order BP with the HWK top cap on may even work well enough as a stop gap.  Another option to try is to iso mount the drivers in place of the top cap.  That will allow more optimum mid teens tuning of the ready made BR alignment.  Starting from scratch cabwise is the last thing I'd do.
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Bob
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #123 - 05/19/06 at 12:21:30
 
LOVING the discussion guys, keep going..  ;D

Weekends are best for letting the HWK "stretch it's legs" so to speek. So I havn't done much listening at high db's during this past week. I do believe it sounds better John. However, I am looking to go lower in the hz, and higher in the db's.  

Tell me if this correct..."Adjusting the port lenth will only change hz range, and not affect db's or prevent driver bottoming out".

If this is true then I would be interested in exploring other modifications. ie, trying iso loading drivers mounted ON the top cap, increasing Vb, or...?... letting more sawdust fly?

Tell me what this would do,...
- Lay original HWK on it's side, facing dual port holes up
- Build carbon copy HWK enclosure facing dual port holes down
- Lay it on it's side, on top of other HWK (the, now "quad holes", mating with each other
- iso mount drivers in the top cap of, say... bottom HWK
- install the adjustable port(s) in 'what would have been' the top cap of upper HWK (now the end of the upper HWK)

Anybody for some ascii?.....
                                                         
                                                         
     -----------------------------------
     I                                               I
     I                                          -----    /__ ADJ. PORT
     I                                          -----    \
     I                                               I
     --    ------------------------------I
     I                                            __/
     I                                           [        /___ ISO DRIVERS
     I                                           [__     \
     I                                               \
     -----------------------------------I

Bob
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60ndown
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #124 - 05/19/06 at 13:56:11
 
no way im going to read all this thread, but if the origional hwk is a good desighn (and im assumeing because steve d desighned it, it is) why all the modding? if built to plans with the right drivers it will deliver lots of accurate bass.mine does anyway ??? in a nutshell, whats wrong with the origional hwk for your application bob?
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60ndown
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #125 - 05/19/06 at 14:00:26
 
turning the knob up just creates the horrible 'klopping' sound from drivers hitting mechanical limit.



ah, the above quote is from bobs first post and seems to be where it all started.seems to me like you need heavier duty drivers. 900 wrms @ 25hz is gonna punish most mediocre drivers.
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60ndown
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #126 - 05/19/06 at 14:02:07
 
[quote author=Adrian D.  link=1145573673/0#2 date=1145626960]series II have only 8mm xmax and can handle 'only' 300w. so my guess is that, with 450w to each of them they're bottoming out.

[/quote]

post number 5?
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60ndown
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #127 - 05/19/06 at 14:04:17
 
[quote author=Bob  link=1145573673/0#3 date=1145628689]Sorry Adrian, I assumed the world centered around me, and that everyone had read the entire thread "amp to make Daytons happy".  ::)  :'(



The Daytons I've got are the series II. They've got an xmas of 15.1, and rms watts of 350, 600 max.

[/quote]

450 still pushes them beyond theyre ability.especially when you really want all that output below 50hz!
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Bob
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #128 - 05/19/06 at 14:17:01
 
Even when the amp gain is at 40%?  :'(

Bob
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John in CR
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #129 - 05/19/06 at 14:18:50
 
Hi Bob,

Lower tuning by lengthening the port will give you excursion control down to a lower frequency, so playing the same content as your last test, you should be able to turn it louder before running into excursion problems.

The tuning frequency of your box is determined only by the net volume of enclosed and the diameter and length of your port.  Increasing the volume, lengthening the port, or decreasing port diameter lowers tuning.  Content below the tuning frequency quickly causes excursion problems, because the alignment can handle very little power below tuning.  Typically a "rumble filter" a high pass filter is used to protect your driver from content below tuning.

The T/S parameters of your driver determine what size box is needed for optimum performance tuned to a specific frequency.  Isobarik loading cuts the Vas in half and the driver only needs to see half the box size for the same performance at a given port tuning.  With iso loading you don't need any more box than you already have.  In fact, the way you have the drivers mounted now gives you an effective volume equal to almost 340L for a single driver and moving the drivers up to the top cap wouldn't help.

At this point I'd suggest trying 2 things:  

First, see if you can live with the SQ and tuning of your current box with the top cap back on.  That alignment will give you more excursion control down low, but it will also limit integration with your mains.  As you saw last weekend, it will allow higher output with the content you were playing in your test.

If that setup won't work for you, then try tuning the existing setup to a lower frequency with some longer ports.

You can use the LFE's you used before for your testing to give you an idea of performance, however, you don't know low that content goes.  I'd mix some more LFE's in for that kind of testing.  Let's say you're tuned to 15hz and the LFE's have 10hz content, you won't be able to turn it very loud and see how your sub performs from 15hz and up.  If you tune to 10hz, then you'll give up a lot of max performance compared to 15hz tuning.  That's where the tone generator comes into play, because it will enable to properly test performance and extension.  Then once you determine the desired tuning frequency, you know what rumble filter you need to protect your drivers which will enable you to crank it as loud as you want without the banging noise no matter what LFE's you send to it.

The bottom line is that you really don't need to let any sawdust fly, because HWKenstein won't integrate with your system.  After trying the stuff above, and you're still feeling adventuresome, then you could try just a single driver (not iso) mounted in place of the top cap using your current port.  That will give you a slightly underdamped alignment close to an EBS alignment.  It won't give you any more output or driver protection below tuning, although it would lower tuning by a couple of Hz compared to what you have now.  It will just tell you what to expect with 2 of the same boxes.  Just test it and add 6db.

You already have butt shakers, so realistically you don't need super low tuning for your sub, you just need a rumble filter.
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60ndown
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #130 - 05/19/06 at 14:27:02
 
i saw some pictures recently of i think your ht room? if that really is how serious you are about your ht then getting something like these



http://www.ddaudio.com/dd/caraudio/woofers.asp?series=3500d


is definately not out of the question.imo Wink
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Bob
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #131 - 05/19/06 at 16:47:18
 
Even more good advise John, That'll keep me busy for awhile.  ;D

Hey 60, a 10.6 lb magnet, OMG! 3 inches Xmas, OMG!!! that's cool, but they arn't very forthcoming with prices are they?
Yes, to answer your question, I am serious about the room. Usually as serious as my budget allows  ::)
2X4's and drywall are cheap, so you can do cool things with design that increase the cool factor and help acustically (hopefully)
As far as the butt shakers go, they stopped working last night!?  ??? Cry
I've heard may referances to rumble filters, mostly seeing plate amps with the filter built in, but I'll do some research on an 'add-on' filter. Sounds like an interesting idea.

....and now for a completely different idea.
You may have see the pic of the rear wall. The drywall is about 9" from the concrete foundation wall, due to the upstairs 4" sewer pipe running across the wall. I didn't want "the ugly box" that a lot of basements have that incase HVAC and plumbing. Soooo, I brought the wall out. The point to all this is, ... IB. Is it feasible? Is it feasible with my drivers?

I've seen the radical set-ups on the infenitly baffled site. Neat ideas

Bob
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Adrian D.
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #132 - 05/19/06 at 17:28:56
 
60, i'd say 2 rl-p 15s.
amp gain@40% doesn't mean the subs are seeing 40% of the power.
one funny thing i noticed on my sub-amp: the x-over has power indicators (these are based upon input sensitivity) and the lower the bass goes the more power the sub is getting. gains untouched. it could be the weird headphone out i use as a pre-amp.
but the thing is that the lower you go down in hz, the more the subs have to move to produce the same spl. 8 mm xmax is pretty limiting.
i agree with john, because lowering the tuning will help. but only untill you will play something below tuning...
sealed could be the best option.  
the subs have to have high-ish qts to use in IB.
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« Last Edit: 05/19/06 at 17:40:05 by adi_ro »  
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Bob
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #133 - 05/19/06 at 18:02:19
 
[quote author=Adrian D.  link=1145573673/120#133 date=1148056136]the lower the bass goes the more power the sub is getting. gains untouched. [/quote]

Well Adrian, That seems pretty obvious now that I see it in writing. I'm fairly dissapointed, and embarassed in myself for not realizing that. Several hundred watts at 100hz is much easier than at 25hz. Thanks for the reality check. That's why you received that A- !

Bob
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60ndown
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #134 - 05/19/06 at 19:03:00
 
[quote author=Bob  link=1145573673/120#132 date=1148053638]

Hey 60, a 10.6 lb magnet, OMG! 3 inches Xmas, OMG!!! that's cool, but they arn't very forthcoming with prices are they?



Bob [/quote]

but you dont get high end per..... really high end perfromance from an entry level sub.$120,000 cars are just that much better than $12,000 cars. sure crazy subs are expensive, but they will give you what you looking for.all the time you invest with 2x4s and drywall etc, thats all worth money isnt it? i say build a hwk the way steve designed it, and throw a pair of serious subs in there, then you get to sit back and enjoy.on the other hand my e bay $40 pair of old skool 15" jbls can fill my garden with enough bass to make me feel quite ill after a few hours Roll Eyes i have used ib installs before and as far as im concerend, the hwk gets as low as any ib stall ive ever used.
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