Welcome, Guest. Please Login or Register
Decware Audio Forums
10/01/14 at 23:42:20


Pages: 1 ... 6 7 8 9 10 ... 20
Send Topic Print
hz numbers on a 15" 2 driver (Read 40444 times)
John in CR
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #105 - 05/15/06 at 12:32:29
 
Bob,

Before the numbers, please tell me exactly what you did in the way of mods first.  After reading that you painted a deck, I'm not sure what to expect.
Back to top
 
 
  IP Logged
Bob
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #106 - 05/15/06 at 13:33:42
 
LOL John,

I didn't use 'regular' paint, it was supposed to be 'FOR' exterior use.  ::)

http://www.behr.com/behrx/act/view/products_detail?prodGroupId=53&catName=Wood+W...

OK, here we go...

- Removed both caps
- Removed both drivers
- Sealed one of the lower holes
- Installed 13" X 4" PVC port tube in other lower hole (slightly enlarging the original hole
- installed lower cap
- clamshelled both drivers in upper chamber (left the cap off)
- wired out of phase

Look ok? ) I think there may have been a Budwieser or two in there as well.  ;)

Bob
Back to top
 
 
  IP Logged
John in CR
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #107 - 05/15/06 at 14:12:48
 
Sorry Bob, just couldn't resist.  I already knew decks were stain only (if anything other than just sealer).  Before I may have tried paint too.

It sounds like you did everything right.  What did the sub sound like?  My guess before hearing your result is that you wired in series instead of parallel (sorry I didn't mention that before) or maybe a receiver setting, amp problem, loose wire etc.
Back to top
 
 
  IP Logged
Bob
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #108 - 05/15/06 at 14:35:10
 
[quote author=John in CR  link=1145573673/105#108 date=1147698768]Sorry Bob, just couldn't resist.    [/quote]

No harm done, I can take it.  :D Undecided Kiss

Wiring comes from amp to the ,... oh, what's it called, the "terminal block" on the sub. Inside the sub, the individual driver wires go directly to the spades on the back of the block, like a "Y" connection. ALL connections are soldiered, soldered? Dammit man, can't spell on a good day, much less a Monday morning.

Is that wired ok?

As far as sound quality goes, I "THINK" it was better, but I was more intent on looking at the meter than listening to quality (although I was listening for Mr. Klop to come to the door  :-X ). It was getting late and testing max SPL on Mothers day evening at dinner time was starting to strain the WAF. Main goal was to get numbers.

Went to Radio Shack to get the meter, the man said they don't have the analog meter anymore. "BUT, here's this cool nifty looking digital meter that's sooooo much cooler".  ::)
Never liked looking at a digital meter for things that "move" across a spectrum rapidly. That's what analog is for. The damn thing was $57 with tax, including the $3 9volt battery they ganked me for.
Shouldn't have bought it, I SHOULD have held out for a "real" meter, but when I have my heart set on something, It's mine. (Just like my 7 year old...Gotta have it now or the world will stop turning.)
Thinking about taking it back?

Here it is.....

http://www.radioshack.com/product/index.jsp?productId=2103667&cp=&origkw=sound+l...


Bob
Back to top
 
« Last Edit: 05/15/06 at 14:36:42 by Bob »  
  IP Logged
John in CR
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #109 - 05/15/06 at 15:33:13
 
Wiring-  Series, parallel or separate?  Series means through one driver to the other then back to the amp.

Did Mr. Klop show up?

What were you playing during your test?  Test tones?

I have an SPL meter.  How many times have I used it?...Less than I have fingers.  How many times have I used it for a sub?...None

Did you put Nemo on and see if it felt like you were in the fish tank when Darla was tapping?  That's a really good test.  Do you have Harry Potter 2?  The willow whomping the car is also good because it has a good variation of frequency as it groans with a nice impact to really feel when it slams to the ground.  Also, the train scene about a minute earlier.  You should feel the near miss of a raging locomotive.
Back to top
 
 
  IP Logged
Bob
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #110 - 05/15/06 at 16:11:00
 
Ok, did (4) tests. First 3 were done never touching amp setting I have it set so the Daytons "just barely" klop. Last test turning amp output from 40% of max to 50% of max. 1st with unmodded HWK, 2nd after mod, 3rd after reinstalling top cap (just for grins) and 4th with more amp power. Chapter 3 in Star Wars III has two fairly long LFE rumbles, and Master & Commander, Chapter 4 has a nice cannon volley.

In parensesis is an (sk), that means I heard a "Slight Knock" from the drivers. No (sk) obviously means no knock heard. the "xxxx" on Master and Commander means the WAF had reached "IT'S max excursion"   Lips Sealed
Measurement taken at ear height, in the center of the 4 HT seats. ( also did a 3' foot distance measurement from the 4" port. The numbers mirrored the seated position measurement, just a few db's higher of course. )

STAR WARS III (chapter 3, 1st and 2nd extended LFE rumbles)


           Decware HKW       after mod      top cap    50% amp
1st rumble   105db(sk)        104db(sk)     105db      107db(sk)
2nd rumble   108db(sk)        107db(sk)    108db      109db(sk)

Master and Commander Chapter 4 Cannon volley
                104(sk)            103db          105db      xxxx

By the way, my 6 horsepower Campbell Hausfeld air compressor produces 88 db from 3 feet.  ;)
Will post numbers at a later date on what my 2 year old daughter can produce db speaking. Would like to know the hz rating. She can reach some unbelievable highs hz AND db's.  :D

Bob
Back to top
 
 
  IP Logged
Bob
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #111 - 05/15/06 at 16:56:37
 
[quote author=John in CR  link=1145573673/105#110 date=1147703593] Series means through one driver to the other then back to the amp. [/quote]

...."back to" the amp?  The "back" is thowing me off..?
Positive and negative to the sub, then "Y" to each individual driver, like a fork in the road.

Nemo on DVD was borrowed, the kids only have it on VHS. I won't even install a VHS in the room, imagine what 480X480 looks like blown up that big....  :-X

haven't tried tones with the meter. The Potter movie you mentioned is on my 'needed' list.  :)

Bob
Back to top
 
 
  IP Logged
John in CR
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #112 - 05/15/06 at 17:40:09
 
Bob,

First, shame on you for testing your sub on Mothers' Day.  You burned up any credits you had and need to do something extra special to get some back.

Second, your tests don't really mean much at all except that they play up to 105db+ at the seating position and that you're playing low enough frequency info to send both the HWK and ported alignments into over excursion.  What it doesn't tell you is how low in frequency you were getting what output.  

Those LFE's have a wide range of frequencies in them.  The cannon shots, for example, probably have a burst across the entire range below the XO point set on your receiver all the way down to about 10hz.  It doesn't surprize me at all that the output was close to equal.  What it doesn't show is a comparison at say 20hz or lower.  Could you hear/feel a significant difference or were you too busy with your new gadget?  Was it enough feel or do you need more, because 105db is pretty darn loud?

If you like the tuning with the top on, that will give you the ability to go louder, because the top chamber is helping to control excursion better than the free air of the open top.

Put the ported end in the corner.  That will give you some boost on the bottom.

Lower tuning (longer port) will enable you to apply more power (go louder and lower) before going into overexcursion on the lowest material.

You should walk around the room while playing the Star Wars rumble to make sure you don't have a placement issue putting your seating area in a relative null.

If after trying all of that you are positive that you want more output, then you need 2 larger boxes, ported and tuned to the frequency you want  OR make your room so it can be closed, which will probably net you about 10db of room gain down at the bottom end of the range.  Your open floor plan prevents much at all in the way of room gain.  Two boxes will net you +6db at the same total power.  Half of your power is currently going to waste for no gain (except smaller cab size) with the isobarik alignment.  You double the alignment (+3db) and double the useful power (+3db).  If you are sure you need more, I'd try HWK size first with only one driver, in place of the top cap, and tuned even lower with say a 17" port.

Something to keep in mind is that with this very low tuning you are getting a shelved response, Extended Bass Shelf (EBS).  Below about 50hz the output drops by 5-6db and stays fairly level down to port tuning.  Typically this is a good match when room gain is factored in netting a pretty flat response.  A max flat response would require tuning to 25hz or so, and you'd give up bottom end extension.  I just question how much room gain you are getting.

Back to top
 
 
  IP Logged
Bob
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #113 - 05/15/06 at 18:35:49
 
[quote author=John in CR  link=1145573673/105#113 date=1147711209]Bob,

First, shame on you for testing your sub on Mothers' Day.  You burned up any credits you had and need to do something extra special to get some back.
[/quote]

Fortunately we have a very stong marriage ( ie...she tolorates my toys)

[/quote]
Second, your tests don't really mean much at all except that they play up to 105db+ at the seating position and that you're playing low enough frequency info to send both the HWK and ported alignments into over excursion.  What it doesn't tell you is how low in frequency you were getting what output.  
[/quote]

Is there something a fellow could get to measure hz and db simultaneously, or would that be yet another toy in the hands of someone not needing more toys?

[/quote]
Those LFE's have a wide range of frequencies in them.  The cannon shots, for example, probably have a burst across the entire range below the XO point set on your receiver all the way down to about 10hz.  It doesn't surprize me at all that the output was close to equal.  What it doesn't show is a comparison at say 20hz or lower.  Could you hear/feel a significant difference or were you too busy with your new gadget?  Was it enough feel or do you need more, because 105db is pretty darn loud?
[/quote]

I believe it was you that said something about the level of sanity regarding your subs.  :) Am I correct  ;D  Yes, I was mainly concerned with the toy last night, but it seemed to be better. Over the next few days, I'll have some real play time to actually HEAR it.

[/quote]
If you like the tuning with the top on, that will give you the ability to go louder, because the top chamber is helping to control excursion better than the free air of the open top.
[/quote]

Would making the top port a smaller diameter create more air restriction, giving the ability to go louder?

[/quote]
Lower tuning (longer port) will enable you to apply more power (go louder and lower) before going into overexcursion on the lowest material.
[/quote]

Install a 90 degree fitting on the PVC to add additional pipe?

[/quote]
If after trying all of that you are positive that you want more output,
[/quote]

Absolutely

[/quote]
OR make your room so it can be closed,
[/quote]

Very hard to do with the archway. Light switch just out of view on right side of arch. And there would be three doorways in very close proximity of each other, all swinging towards each other.

[/quote]
If you are sure you need more, I'd try HWK size first with only one driver, in place of the top cap, and tuned even lower with say a 17" port.
[/quote]

I'd like to go down this path.


...Gee, I hope all this quoting works.

Bob
Back to top
 
 
  IP Logged
Bob
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #114 - 05/15/06 at 18:37:36
 
Well, that looks like hell. But I suppose a fairly smart guy could figure what it was I was attempting to do.   Roll Eyes

Bob
Back to top
 
« Last Edit: 05/15/06 at 18:38:17 by Bob »  
  IP Logged
John in CR
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #115 - 05/15/06 at 19:46:22
 
Google  "ttg test tone generator free" and download Timo Esser's tone generator that is free for a month.  If your puter isn't connected to your system, just make some tone files and sweeps and burn them on a disk.  Then you play a frequency from the generator and measure it with the SPL meter.

Be absolutely sure your other speakers are set to small or are off for running that kind of test or you'll blow them for sure.

Keep the port outside the box, so you can easily try different lengths first.  Don't put it inside until you get to the tuning you want.

You might be able to get away with a matched pair at the front of the room in the corners with the right color scheme.  I think that will load your room better, but that's probably just a few dbs at most.

Before building something new, check the SQ and max limits with the top cap on.  Also with the top off and lower tuning.

Yes I think a smaller diameter port and/or longer port will help control excursion to a lower frequency, but too low tuning could cancel some output from the big chambered end because they are at a different phase.

Just for grins, next time you have a sheet of ply or mdf, before you cut on it, place it over the opening leading out of the room and have someone hold it in place while you play some loud LFE's to see how much more room gain is possible.  That way you know whether or not it's worth trying to figure out if it's worth any trouble trying to make that work.

I'd say measure and listen to what you have first.  Going for extreme output is kinda fun, but realistically it will never be used, because your volume would be up way too loud for the rest of the audio spectrum.  Plus, if you do use it, you'd have to start worrying about cracks in sheetrock joints and other damage to your house.  Also, Dad's setting the example now, you may not enjoy the 7yro's taste in music in a few years and he/she will want to blast their's too.

Keep in mind that HWK size is about 100L too small for true EBS tuning.  It looks like Bassboy and I are going to try some new that we've been discussing over in the HT section.  If my 10hz version works, using a 15" driver, then that might be your answer once you want to cut some wood.  Tom Danely, a renown sub designer, is getting 120+db at 20hz with a pretty compact model with a 12" driver.  Mine will be 8ft x 1.5ft x 3 or 4ft and it looks like you have room for that behind your seating area.  http://news.ecoustics.com/bbs/messages/10381/169045.html
Back to top
 
 
  IP Logged
Bob
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #116 - 05/15/06 at 22:15:24
 
John, that's a lot of very good advise you just gave. Endless tweeking..... Several weekends worth I'm sure.

I like the specs on the HVAC cold air return you gave ( well, that's what it looks like  :) ). Very impressive. But for 3 grand + shipping + suitable amp, I can play in my toy room for a looong time spending the $$$ elseware.

I have been lurking the thread with yourself and bassboy with great interest. Yes I'm luck in that respect, PLENTY or room behind the seating. (unplanned, over-exagerated projector throw distance/screen size specs given by the manufacturer provided me with lots of extra room. Putting the seating where it was originally planned would put the PJ at adams apple level imediately after standing up from the seats.  >:()

I have thought about a temporary "door" but if memory serves, the opening is 5'wide 7'tall. Would have to make something. Really regret not having a door there. Didn't think I needed one 3 years ago when I built it.

Thanks again John. I'll be hanging in the HT thread to see what my next POSSIBLE project would be if the HWK doesn't work out.

Bob
Back to top
 
 
  IP Logged
Bob
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #117 - 05/18/06 at 22:39:17
 
[quote author=John in CR  link=1145573673/105#116 date=1147718782]
Keep the port outside the box, so you can easily try different lengths first.  Don't put it inside until you get to the tuning you want. [/quote]

So, let me get this right.  The total port lenth isn't the issue, it's how much of it is inside the enclosure? Does it affect tuning at ALL, or just not enough to worry about for tuning purposes only?

Bob
Back to top
 
 
  IP Logged
John in CR
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #118 - 05/18/06 at 22:56:44
 
[quote author=Bob  link=1145573673/105#118 date=1147988357]

So, let me get this right.  The total port lenth isn't the issue, it's how much of it is inside the enclosure? Does it affect tuning at ALL, or just not enough to worry about for tuning purposes only?

Bob [/quote]

Bob,
The port length and diameter is the only issue with a cab that large.  When it's inside the box, the volume taken up by the port (and the volume taken up by the driver) is subtracted from the total volume to get to the Vb (the volume of air being tuned).  In your case the volume taken up by the port is immaterial in comparison, so you can determine the tuning you want by fiddling with your port length with it outside of the cab.  When you get to where you want, then worry about how to fit it inside the cab.  ie  Don't worry about 90 degree bends and stuff now.  Also, you can try different tuning in seconds, instead of having to take the bottom cap off and make changes.
John
the world's foremost believer in the KISS principle.
Back to top
 
 
  IP Logged
J_Rock
Ex Member



Re: hz numbers on a 15" 2 driver
Reply #119 - 05/19/06 at 00:50:59
 
I have been whatching this thread for some time.  I believe for home theatre you need to stop and step back.

Now realize the HWK is not going to work.

Now start over from scratch.  Working around the space, drivers and amps you have, design a new enclosure.  For hometheatre and double duty as music, the only option IMO is a low tuned ported enclosure (PR if needed).  

No offense, these ideas are great, but I think you have a much better idea of what you want, and can easily get it without haveing to modify a box.

And guessing at volumes and ports is fun for a few hours, but after awhile grows tiring, I suggest a program to model something.  Even if it is just to get a starting point...

Back to top
 
 
  IP Logged
Pages: 1 ... 6 7 8 9 10 ... 20
Send Topic Print