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hz numbers on a 15" 2 driver (Read 25294 times)
Bob in St. Louis
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #200 - 06/06/06 at 20:42:39
 
OK bassboy, John gave me a couple ideas, we're trying the small/easy/cheap version first. If memory serves, here's the current configuration;
One hole is closed
Other enlarged to fit 4" PVC, I think it's 17" long
Drivers clamshelled in/on top baffle
Drivers out of phase
Amp is bridged (900W)
Top lid off, then on, then off, now it's on.

You know 60, I saw your mug on the other post. It's scary how much we look alike.

Bob
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Bob in St. Louis
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #201 - 06/06/06 at 20:50:22
 
By the way 60, --"bass, the final frontier!"?

Do you really mean it?

Bob
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60ndown
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #202 - 06/06/06 at 21:01:36
 
[quote author=Bob in St. Louis  link=1145573673/195#202 date=1149623422]By the way 60, --"bass, the final frontier!"?

Do you really mean it?

Bob [/quote]

its a play on words with startreck (1st series) and my love of bass Wink

"captins log......etc etc.........................."
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60ndown
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #203 - 06/06/06 at 21:04:50
 
[quote author=bassboy  link=1145573673/195#200 date=1149620270]60, I don't disagree with a single thing you said this time.  But you are neglecting a few points that we have made.

Not every sub is ideal for every purpose.  For example, the low tuned subs we are planning would absolutely suck where the HWK excells.  Even more to the point, your HWK measures completely different in the garden than it does in the corner of a small room.  Don't tell me it doesn't, unless you live in some other dimension.

The proposed other solutions (EBS ported and huge bandpass) are also tried and true options, they just weren't offered as plans by Steve.  The only product in the Decware lineup that is going to do what Bob wants is the imperial SO, that's just the way it is.

And furthering your alalogy of airplanes, a stealth bomber is not going to help you much if your need is really for a passenger jet.  (Notice I equated the HWK with a stealth bomber just to make you happy.)

By the way, I would encourage you to measure again.  Unless you have an Imperial SO, I doubt very much anything you have built is hitting 20 hz flat.  They just simply were not designed to do that.  What you just described in your HWK assessment is an F3 at 23 hz.  We are talking about F3's below 15, which may not seem to be an incredible difference until you look at the exponential nature of the FR line.  To be fair, I have only tried a WO and Imperial, both with inadequate drivers, but common sense tells you that you need bigger boxes and lower fs drivers to do 20 hz flat.  The only reason the Imperial SO is flat at 20 hz (as it is theoretically too small as well) is that Steve is ingenius in his designs, no one is disputing that at all. [/quote]

Using musical instrument woofers (ex. PEAVEY BLACK WIDOW) you get tight full accurate bass from 200 down to 40 HZ. Using subwoofers you get big warm full bass that can on command create Subsonic pressures lower than 20 cycles.  
??? Roll Eyes Cheesy Grin Wink Kiss Embarrassed
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Bob in St. Louis
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #204 - 06/06/06 at 21:23:43
 
60, I was trying to ---  :-* --- with the 'frontier' comment, you didn't fall for it.  :)

I've quoted that very same line directly from the "pretty picture page" of the housewrecker ad.

It's been shot down many times. much to my dismay.
Steve hasn't devulged [sp] how he got there from here.  :'(

You never answered my question about your HWK and the critters.
You got pics yet of the landscape ?

Bob
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bassboy
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #205 - 06/06/06 at 21:32:42
 
Where in there does it say it's flat to 20 hz?  My imperial is flat to 40 hz, but you better believe it can create subsonic pressures lower than 20 cycles.  Let's see some FR graphs, please.  With real drivers in real conditions, please.  I don't post pictures, but if you want, I will gladly link to a spot showing a FR graph of my current unfinished (almost unstarted) project, clearly showing predicted response flat to about 18 hz in a box which is probably smaller than the HWK (but I assume not capable of anywhere near the brute SPL).  That's using the Dayton Quatro, the Series II's 4 ohm brother.  And that's before I start modding it Jensen style for a killer low end.

Measure your box, my friend, get out your meter and do some charting but be sure to mention where it was measured - outside, small room, corner loading, etc.  I'll guarantee both our boxes will sound good, so the differences will be pure SPL and FR.  You have chosen higher tuning and higher SPL, I choose lower tuning and lower SPL.  (Although I'm hoping for 95 db at 1 watt, shouldn't too far from yours)
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60ndown
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Re: hz numbers on a 15" 2 driver
Reply #206 - 06/06/06 at 22:01:30
 
my only measureing tools are my ears, what critters?

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Bob in St. Louis
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #207 - 06/06/06 at 22:06:49
 
Nice yard, VERY nice fence!

Do your ears fall off below,.... um... ?? How low?   ???

Bob
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J_Rock
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Re: hz numbers on a 15" 2 driver
Reply #208 - 06/06/06 at 22:11:13
 
research normally says 20hz.  But I feel (after reading some articles on ultra low high SPL sound, that we can hear below that.  It's just that our sensitivty to these sounds drop off at such a large rate, the sound level required for us to HEAR 15 hz is extremely high.  Normally we feel these sounds before we hear them.

An excellent example would be the large Barges that float down the Mississippi nearby.  When I am laying in bed at night I can hear them.  And while I listen I can count the peaks in the sound.  The frequency basically.  Now wether this is the beat effect or actually a wave I am hearing is still to be known...
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Bob in St. Louis
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Re: hz numbers on a 15" 2 driver
Reply #209 - 06/06/06 at 22:17:21
 
Ok bassboy, way back on post #201.
Does that give you the information you need?

J_Rock, I've heard (no pun intended) that humans can hear down to 20 just like you have heard (ok, pun intended that time) but I agree with you, that we can hear well down into the teens.

Bob
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bassboy
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #210 - 06/06/06 at 22:36:55
 
Bob, I have to admit that I haven't done the calculations on any of the suggestions John and others have posted.  I have full faith that if John says the box is tuned at 19 hz, then it is.  If you chose the right length of port, it should perform as described.

But just if you want to be sure, plug the driver's specs into WINISD (it even allows isobaric loading as an option) and model the suggested box.  Then go to the next tabs and change the box size and port length to your box size and port length.  What you see in WINISD is what you should hear in your room, but with a bit of room enforcement on the low end, and even more for corner placement.

Keep fiddling with WINISD until the curve looks like what you want to hear, it's fun and free.

Try playing with flared ports too, it's good for you.
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« Last Edit: 06/06/06 at 22:38:16 by bassboy »  
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bassboy
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Re: hz numbers on a 15" 2 driver
Reply #211 - 06/06/06 at 22:39:40
 
And if you can't find ALL the specs, you have to download the manufacturer's driver specs in pdf, I found out they are all there.
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John in CR
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #212 - 06/07/06 at 01:55:30
 
The bottom 2 chambers of Bob's box nets to about 155L (net of driver and port).  With the 13.5" long 4" port the tuning is just above 19hz, but with that corner placement he's getting an effective length of over 15".  With the isobarik loading, the drivers are acting the same as a single driver in a 310L box.  It's closer to an EBS type alignment but with a small box.  Even though he could lower the tuning, the port would turn into a problem because it would get so long.

So no Bob's box isn't flat to 19hz, but the few db sacrifice for the added shelf of extension is offset by some room gain.  In room, Bob should be pretty flat down into the upper teens even though his layout doesn't give him maximum room boost.


Bassboy,
I'm pretty sure that 95db on 1 watt at 20hz is a pipe dream (excuse the pun).  I think only a giant bass horn or multi-driver rig will do that.
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John in CR
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Re: hz numbers on a 15" 2 driver
Reply #213 - 06/07/06 at 02:10:09
 
Bob,

How about if I throw you a real curveball.  If you only connect 1 of the voice coils on your drivers, it is almost identical to the Dayton IB15.  That means you also have the capability of going OB or IB with those drivers and even get the added advantage of fine tuning the sound with RDO (Resistive Damping Operation) using a variable resistor across the unused terminals.

What's on the other side of the wall behind your screen?
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bassboy
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Re: hz numbers on a 15" 2 driver
Reply #214 - 06/07/06 at 03:52:02
 
The Tower of Power does 95 db.  My traditional design models at 93 in open space.  With Transflex loading, corner loading and room gain I am hoping for 95 db at 1 watt at least way down low.

I would be thrilled with that level, and I am hoping for that much volume but we'll see.
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Bob in St. Louis
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #215 - 06/07/06 at 12:45:10
 
John, my drivers are Single Voice Coil...

http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=295-130&CFID=4954...

The depth of the surrounding cabinets is about 18", the back of the cabinets are about 1 1/2', slightly less from the sheetrock wall. The thickness of the screen is about 1". The screen is "torsion panel" construction, like a cheap interior hollow core door. The distance from the back of the screen to the wall behind it is right at 30". Currently the space is storage. The screen is hinged at the top, and 'flips up' like a giant car hood. My original plan back there was to put shelving for storing 'stuff', but just havn't gotten around to that particular project. So the 'stuff' is just sitting on top of the cabinets.

So yea, I've got plenty of space back there, cubic feet wise. But that may be irrelevant if were not talking about the correct drivers.

Bob
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bassboy
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #216 - 06/07/06 at 18:26:08
 
Bob, overlooking the DVC issue, the end results are not irrelevant.

The important thing when designing EBS ported is the box and port tuning.  As long as the box and port are tuned to work together, the driver is the only responsible for putting out whatever it can at the requested frequency.

The box will output whatever sound the driver presents it with at the box's tuning frequency.

The problem comes into play when you tune the box and port WAY out of the driver's range, which you haven't.  The cost in that case is sensitivity, because the driver is struggling to make sound way below it's resonance and we've all seen the FR graphs that show heavy rolloff around fs.

I strongly urge you to play with WINISD, you'll learn more there much more quickly than anyone can explain anything.  It's an excellent visual tool that you can experiment with.
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« Last Edit: 06/07/06 at 18:27:15 by bassboy »  
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Bob in St. Louis
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #217 - 06/07/06 at 19:58:24
 
bassboy, I've played with WinISD, it is pretty cool. Somewhere around page 3 or 4 of this thread I mentioned to John, that the program was giving me the message, "this version can't perform that task, you looser". I guess I need "PRO" version?
It is fun to play with though.

Bob
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John in CR
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #218 - 06/07/06 at 20:13:54
 
Bob,

It would be nice to know once and for all which drivers you have.  Back on page one you gave us a link to these, which have 15mm of Xmax (that's almost a 6db difference at the bottom end):  http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=295-190

Let's get on the same page before proceeding.
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Bob in St. Louis
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #219 - 06/07/06 at 20:38:11
 
John, I'm sorry. Your reading post #3 which is the one I said I have Part#295-190 (DVC's)
On post #8 I apologized, corrected my mistake by saying I have Part # 295-130 the single voice coil.

I though about deleting/modifying post #3 so thing like this wouldn't happen. I figured I'd leave it alone since it would "F"-up the 'story line'.  ::)
I didn't think by now, anyone would have gone back that far, or would have read further down and see the correction.

Again John, I'm sorry.
I do sincerely Thank You for the time you've spent with me.

Bob
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bassboy
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #220 - 06/07/06 at 20:54:22
 
Bob, WINISD cannot model the HWK or 6th order bandpass but it does very well with isobaric vented, which is what you have.

I'd go through the motions but I don't post pics so it's meaningless for me to do it.
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John in CR
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #221 - 06/07/06 at 21:20:05
 
Bob,

I think we're back to where you should give a good listen to what you have (drivers in top baffle clamshelled, one bottom port blocked, the other with a 13.5" or so long 4" port.  I think with the top off will be easier to blend with your mains but check it out, since the top on gave you better control over excursion.

Then play some of your DVD chapters with the sound at a good level overall and note whether you're getting pretty good oomph on your LFE's.  Keep in mind that later you can split the drivers up and put each in a box twice the size with the same tuning and get the same sound but +6db in potential.  You can also add a rumble filter at say 15hz which will give you more potential at 15hz and higher.  With only 8mm of excursion, I think you should forget about going lower than 15, but don't worry there's plenty of feel in the LFE's 15hz & up.
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Bob in St. Louis
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #222 - 06/07/06 at 22:28:19
 
John, I don't know where we're at now in the hz department, but I think I'd take the 15hz/rumble filter idea over the +6db gain since I'd have to build two boxes twice the size of my existing one to get there.
I'll take bassboy and your suggestion first. Remove some wires, listen to the mains then slowly add wires/equipment and gentle tweek along the way.

After I do that, I think I'll play with room treatments.
This is cheap/easy, don't laugh if it's a dumbass idea.
Take all of the cushions from the sofa's / loveseat's from upstairs furniture and line my walls with the cushions.

I've got to think that the room is playing into this. Despite how much time/effort I put into the room (with acustics in mind) that it turned out good enough not to need SOME form of absortion/diffusion.
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John in CR
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #223 - 06/07/06 at 23:17:54
 
If you want to see what bass traps might do, haul a couple of mattresses down there too.  Are the recessed areas on the ceiling in front of the seating area reflective or do you have acoustic tiles up there too?

BTW, the rumble filter would be needed with the 2 box approach as well.
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60ndown
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #224 - 06/07/06 at 23:34:03
 
mattresses on the celing? man alive, i laugh at myself sometimes trying to move my hwk and other subs, im sure they weigh in excess of 100lbs and awkward as a dead elephant . but im sure i would collapse into a ball of hyseria trying to fix a mattrress to my celing, bet the wife would love it 2 Roll Eyes
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John in CR
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #225 - 06/07/06 at 23:39:53
 
60,

You must get in trouble with the wife all the time misinterpreting what people say.  Mattress on the ceiling?  :'(
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Bob in St. Louis
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #226 - 06/08/06 at 14:25:57
 
60, "AFRS" in the other 'active' HWK thread just told me the HWK is 140 pounds. (10 stones BTW, just in case that's your form of measurement.  ;))

John,  mattress is a good idea. I've thought about that, but I'm too lazy to drag a "califorina king" mattress down a flight of stairs.  ::)
Might rob the kids crib mattress (but it's plastic coated)
Or my son's 'twin' mattress  ;D

Cieling tiles are USG 2X2 acoustic, (very heavy compared to the cheap/standard white one's) They've got a very agressive texture on them.

Bob
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John in CR
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #227 - 06/08/06 at 15:41:49
 
Bob,

I was just making sure those recessed boxes weren't highly reflective.  Is it a basement?  If so, which walls are concrete?  Sure room treatments can always help, but from the photos it doesn't look like something I'd be in a rush to blame.  Unless you have some parallel concrete walls creating havok with room modes, you can throw room treatments under the header "fine tuning" on your list.  A 20-200hz tone sweep, can tell you if you have mode problems.  That will also reveal any holes in response with your sub/mains integration.  

I was asking what's behind that wall in front, not behind the screen.  Can't put a sub behind a screen anyway...too much air movement.
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60ndown
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #228 - 06/09/06 at 02:22:19
 
[quote author=John in CR  link=1145573673/210#224 date=1149718674]If you want to see what bass traps might do, haul a couple of mattresses down there too.  Are the recessed areas on the ceiling in front of the seating area reflective or do you have acoustic tiles up there too?

[/quote]

cmon it was a fair misinterpretation? first matresses get mentioned and then the celing?
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bassboy
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #229 - 06/09/06 at 02:39:29
 
Technically, mattresses on the ceiling would work for higher frequency bass, at least to some extent.  Placing them standing up, across a corner, however, would probably get a lot more mileage out of them, and work on a broader range of frequencies.
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John in CR
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #230 - 06/09/06 at 02:45:18
 
60,

Are you sure you aren't from Mississippi?

Those of us from Louisiana thank God on a daily basis for giving us Mississippi.  That way someone else gets to be #50 in almost every category. Grin
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« Last Edit: 06/09/06 at 02:47:16 by JohnF »  
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Bob in St. Louis
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #231 - 06/09/06 at 12:20:18
 
John, it is a basement. 3 walls are concrete. Front, (behind the screen), the Back, and right walls are your standard basement foundation walls. Standard 2X4 walls with insulation. The only wall that deviates from the norm is the back wall. The drywall is somewhere around 8" or 9" from the concrete. This was done so I could avoid the various ugly "drywall framed boxes" people use to 'encase' the plumbing. I wanted a cleaner look. All walls in the basement are insulated with 'the usual', including interior walls.

Ok, who's comin' over to help with the mattress installation?  :-/ I'm going for all walls, floor and ceiling.  :-*

Ok, not really.

Bob
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« Last Edit: 06/09/06 at 12:21:40 by Bob »  
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Gex
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #232 - 06/09/06 at 13:09:10
 
Hey 60 don't feel bad about being 50.
Canada is the state that Americans did not want.

Thats a joke. in case  put anyone in a crank.

Funny you should mention the mattresses ( not the ones on the ceiling) I have a heck of a time getting my wife to throw out old mattress. maybe I could convince her to recover them with nice fabric and store them were the stereo is. Then I could get the stupid things out of my office.
Its so quiet in there I can can't hear myself think and I have to, or I don't think.
could be the reason for the last 100 or so posts  :)
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Bob in St. Louis
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Re: hz numbers on a 15" 2 driver
Reply #233 - 06/09/06 at 13:18:27
 
Line your walls with old mattresses from the "junk store", saves money on drywall. Saves time on mudding the joints.  ;D
And just think, NO PAINTING!

Bob
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ado420
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #234 - 06/09/06 at 16:24:00
 
[quote author=Gex  link=1145573673/225#233 date=1149854950]Hey 60 don't feel bad about being 50.
Canada is the state that Americans did not want.
[/quote]
Really?
Because I always thought Canada was the state for Americans that aren't liked amongst other Americans  :D
Except for Alaska, that's an even further, more boring, exile.
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ado420
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #235 - 06/09/06 at 16:25:42
 
[quote author=Bob in St. Louis  link=1145573673/225#234 date=1149855507]Line your walls with old mattresses from the "junk store", saves money on drywall. Saves time on mudding the joints.  ;D
And just think, NO PAINTING!
Bob [/quote]

Ya, you don't have to paint because someone already beat you to the punch  :)
That's why it's in a junk store
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John in CR
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Re: hz numbers on a 15" 2 driver
Reply #236 - 06/09/06 at 16:56:56
 
Bob,

You're getting some bass trapping with those interior walls over the concrete walls, but they're probably all tuned the same.  Next time you can incorporate a panel bass trap design into the construction at essentially no cost.  I did that in my room and my entire room is a giant bass trap tuned to a very wide range of frequencies.  I don't need any additional bass treatments.  Your room probably isn't too bad at handling bass either.  A LF tone sweep will tell you a lot.

How much air volume do you think is enclosed with that back wall?

How difficult would it be to move that front cabinet/shelf unit away from the front wall?
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60ndown
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Re: hz numbers on a 15" 2 driver
Reply #237 - 06/09/06 at 17:32:10
 
[quote author=John in CR  link=1145573673/225#231 date=1149817518]60,

Are you sure you aren't from Mississippi?

Those of us from Louisiana thank God on a daily basis for giving us Mississippi.  That way someone else gets to be #50 in almost every category. Grin [/quote]

i must be number 51, i have no idea what you just said.
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John in CR
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Re: hz numbers on a 15" 2 driver
Reply #238 - 06/09/06 at 18:07:32
 
60,

I thought you were changing your name to 40nUp.  You understand that one don't you?
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Bob in St. Louis
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #239 - 06/09/06 at 18:14:20
 
[quote author=John in CR  link=1145573673/225#237 date=1149868616]How much air volume do you think is enclosed with that back wall?

How difficult would it be to move that front cabinet/shelf unit away from the front wall? [/quote]

Are you looking for the volume behind drywall including the 4" insulation, or volume between back of insulation to the concrete?

Horrible PITA to move cabinets. Don't know if it's possible with the way the screen attaches to the wall. (wouldn't have a wall to fasten to anymore if it's moved out)

Bob
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« Last Edit: 06/09/06 at 18:15:53 by Bob »  
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John in CR
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Re: hz numbers on a 15" 2 driver
Reply #240 - 06/09/06 at 19:40:01
 
[quote author=Bob in St. Louis  link=1145573673/240#240 date=1149873260]Are you looking for the volume behind drywall including the 4" insulation, or volume between back of insulation to the concrete? [/quote]

If it's less than 100cuft don't worry about it.  If it's more, then approximate total volume behind the drywall.

Quote:
Horrible PITA to move cabinets. Don't know if it's possible with the way the screen attaches to the wall. (wouldn't have a wall to fasten to anymore if it's moved out).


I was hoping just a handful of screws holding the whole unit to the wall.  Move the light fixture on the right.  Move the cabinet unit out 18-24", and build a new wall with the airspace behind to house 1 or 2 IB manifolds.  Then just replace one of the panels with a grill to vent it into the listening area.  You sub would be out front where it belongs.  Extreme extension and output is easy.  No worries about integration with mains up to 80 or 100hz.  Your projector can move back and you get a bigger image ratio, and no big ugly sub to hide.
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Bob in St. Louis
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Re: hz numbers on a 15" 2 driver
Reply #241 - 06/09/06 at 21:12:34
 
[quote author=John in CR  link=1145573673/240#241 date=1149878401]If it's less than 100cuft don't worry about it.  If it's more, then approximate total volume behind the drywall. [/quote]

Without being at home, and the ability to measure the wall, I'm at a handicap. Hears a close guess. Under the 'cove' the wall is about 7' tall, we'll call the drywall .75 feet from concrete, and wall is about 20 feet long. I'd call that 105cu' which sound close enough to need an accurate measurement. I'm assuming an IB needs essentially no 'sealing' in the cavity the magnet is in.? The cavity between drywall and concrete is 'open' to all sides but the floor. It's as sealed as a 2X4 could be when next to concrete.

I really like the idea of an IB in the screen wall ( Yea, I've seen "The cult of the Infinitely Baffled". Cool stuff! )

When I started this project, I had never heard of IB.  ::)

Man that would be a huge undertaking, dealing with moving the screen and cabinets.

        l
        l
COVE \/    X         X         X joists X        X         X
------------+-------------------------------------
               l l                   ceiling tiles /\
               l l                                   l  
__________l l
                 l  <----- screen
                 l
                 l
                 l                      seating ------->
"open area"   l
                 l
-------------l
                 i
                 i
                 i
 cabinets     i
                 i
                 i
                 i
                 i                                 floor
------------------------------------------------------

Ok, the 'cove' is very permanent. Never to move. The "+" sign is the hinge for the screen (actually on the facing wall of the cove) If I pull the screen out, even a fraction of an inch, I'd have to 'reinvent the wheel' attaching it to something. Dealing with the tiles, and joists above to hang it from the ceiling instead of a wall is a bigger PITA than I think I want to get into.

Now the back wall,... I'm wide open.  ;D

Bob
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Bob in St. Louis
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Re: hz numbers on a 15" 2 driver
Reply #242 - 06/09/06 at 22:59:57
 
You got me thinking John.   Smiley

Talk to you Monday. (here in the 'upper 50') Don't know what time it is there.  :P

Bob
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John in CR
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Re: hz numbers on a 15" 2 driver
Reply #243 - 06/09/06 at 23:26:03
 
IB just means the front radiation is kept separate from the rear radiation and the rear air space needs to be of sufficient volume that the driver cone operates like it is in free air.  The typical recommendation is 8 times Vas, but you can get away with less.  eg For the IB15 driver Dayton recommends at least 15cuft of box volume for each driver (less than 1.5xVas).  How well the airspace enclosed by the rear wall can be used for IB will depend upon how freely the air can flow in that enclosed area.  The drivers you have aren't suited for IB use anyway, just trying to help develop a good plan when you are ready to upgrade.
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Bob in St. Louis
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Re: hz numbers on a 15" 2 driver
Reply #244 - 06/12/06 at 17:19:27
 
John, I think two things have helped my rig.
#1 Your advise on the sub. The tweeks have helped. I've played with some of those car audio bass cd's (you know, the woofer torture discs). This sub could be used for a room fan. The air coming from the lower port is amazing (scary actually). WITH NO KLOPPING.  :D

#2 My maturity level. I've turned down the overall receiver/surround volume, and turned the sub amp up, quite a bit actually. I suppose I was so interested in the HT "escape" that I thought the entire experience had to be loud. Like a good song you crank up. (However, a 2 hour long cranked up movie leads to fatigue.) But was still looking for the 'punch' from the sub. Well, at that volume, the sub was already at 90%. Not much headroom left. So, turned the receiver down, sub amp up. Gives it the nice little suprise when the movie requires it. Didn't really change placement so to speak, but twisting it on it's axis so the waves have to take a different path has helped somewhat.

I guess I'm an official member now of the housewrecker club. One of my favorite cocktail 'hurricane' glasses I got from Bubba Gump's Shrimp Company in Chicago broke.  ::) I truly had mixed emotions about that one. Pissed that I broke it, but had an uncontrolable grin as I walked past my wife to get the vacuum cleaner...... Thinking to myself as I cleaned the broken glass, "Yea, I got me a badassed sub, I can break shit now."

I'm beginning to realize some of my unhappiness with the system is due to me. I've always had a problem with wanting to make something that works perfectly fine, better. We all know my setup would not be considered audiophile grade. I hear you guys talk about your systems knowing mines nowhere close. Man, I can't imagine how some of your systems sound (charlieboy's, Mr. C's ect..ect..). Granted they're listening rooms, not HT, but there is no law that says you can't have both. I guess knowing that there is something out there that's sooo much better acoustically than what I'm hearing from mine is what my biggest problem is. I'll never be happy.  :(
I'm not at all embarrassed about my system, I'd show it proud to any of you guys. Knowing all the while your probably thinking, "this sounds like hell. I can't wait to get back to MY room". But proud none the less.
I could stop on the room right now, never tweek another thing and be pretty happy with it. I'd continue to have friends/relatives over and show it off. BUT, I know myself, and will continue to tweek/complain/modify/spend money/bitch untill I'm blue in the face.

So John, as far as your comment about being ready to upgrade,.... I'm always ready (just not ready to move walls yet  ;)) ... you just keep those radical ideas coming. I'll build 'em...
Can't wait for you and bassboy to design that W.M.D. your planning.   Smiley  I'd build it, as long as the drivers is'nt super high dollar.

Bob

EDIT- just proofread after posting, apparently the website censored me when I wrote "c0cktail", it replaced it with thingytail!? ... WTF? a totally innocent word censored by a website.  >:( (had to use a zero instead of an 'o' to get it to work that time.) Apparently "it" doesn't have a problem with me using other 4 letter words though.  ::)
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« Last Edit: 06/12/06 at 17:31:03 by Bob »  
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Bob in St. Louis
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Re: hz numbers on a 15" 2 driver
Reply #245 - 06/12/06 at 19:46:54
 
In an effort to further educate myself (surfing the net) I ran across this...

Specifically look for the clock, and the jar of rocks.

http://www.machinadynamica.com/

I wasn't feeling bold enough to start it's own thread.

Bob
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jj420
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Re: hz numbers on a 15" 2 driver
Reply #246 - 06/12/06 at 20:28:44
 
for such a "popular" product, that clock has very little to back it up.... there's not even a white paper on it, I am not certain a passive device such as this could actually improve the sound in a room.  I would have a much easier time believing it if there was more to digest on the site than some reviews of questionable objectivity, along with the alway suspect comments from "customers"

The pebbles on the other hand, I can see those working, I always weigh my speakers down with something, helps the definition a little.  At the ame time, a sort of " phase plug" in corner helps to break up refractions in these problem areas.

Magic rings, stage expanders, isolation platforms, this may show my ignorance, but the site is either a snake-oil cart, or a shop out of AD&D...

and all of it at bargain basement prices!!!! I cant wait to give them my account number HAH

almost always skeptical
JJ
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Bob in St. Louis
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Re: hz numbers on a 15" 2 driver
Reply #247 - 06/12/06 at 20:58:29
 
I understand the principle of weight on a speaker enclosure, but the ounce and a half the glass jar of rocks provide wouldn't do didley squat. (except rattle and buzz).

Bob
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John in CR
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Re: hz numbers on a 15" 2 driver
Reply #248 - 06/12/06 at 21:12:52
 
Bob,

I thought you were in St Louis.  I ran accross a Missouri audiophile group on Audio Circle and it was filled with nothing but "believers".  Since when did Missouri go through the gross transformation away from being The Show Me State.  If it sounds too good to be true, guess what, it is too good to be true.  

You want a jar of colorful rocks, fine buy a jar of colorful rocks.  You want to buy a digital travel alarm clock, buy one.  You want to separate you rig from vibration with weight and springs, fine, learn the math and do it right with the appropriate mass and springs, just don't go out and pay $25/ea for 25cent springs.  In any other business, vendors like that end up in jail for fraud, yet audio welcomes them with open arms.
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Bob in St. Louis
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Re: hz numbers on a 15" 2 driver
Reply #249 - 06/12/06 at 21:44:42
 
John, I've read some of your conversations with my geographic brethren. Funny stuff. (Although not funny for those involved)   Tongue

Yea, Missouri IS the 'show me state", but I didn't need anyone to 'show me' those things.  ::)

I've been trusting (nieve) before, but that's just stupid. Anybody that buys that... well, you know.

Hey John, do you have any pics of your setup?

Bob
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