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Sub-Woofer Question - AudioPhool Experts (which I am not - an expert, that is).




 
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Author Topic: Sub-Woofer Question - AudioPhool Experts (which I am not - an expert, that is).  (Read 23565 times)
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steve_qix
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« on: December 13, 2009, 02:03:41 PM »

Hi !

For many years, back in singledom, I had some very LARGE (60 inches x 32 x 24) inch speakers (sub-woofers, really) situated in corners of my living room.   These speakers had excellent low frequency response (down to single digits), and were good and loud.... I had seperate amplifiers, located at the speakers themselves, low level crossovers, etc. etc.etc..everything homebuild.  Audio bliss prevailed.

Ok, fastforward - 2001 - I meet Sherrie.  Sherrie moves in, and unfortunately, she HATES the big (ugly) speakers, and after careful consideration, the speakers and not Sherrie are banished to the basement..... and there have been no audio frequencies below about 50 cycles reproduced in this house since (except through headphones).

So here is today... we have recently moved a bunch of furniture around and - low and behold, there is a perfect corner just WAITING for a nice big sub-woofer..... so long as it passes the muster with Blonde Central (which means it has to look good and not be overly obtrusive.. I think I can actually get something that sounds good.

I know there are some fine sub woofers out there.  I was looking at one made by SVS - claims to be fairly flat down to 10 Hz, with plenty of power.  The only downside of all this is cost.  My big speakers were relatively inexpensive to build.  These subs are BIG bucks.  Oh well  - the cost of providing a chick-friendly environment, I guess  Cheesy

Any ideas? Suggestions? Experiences with good subs?  I'm all ears (as Ross Perot would say!).

Regards,

Steve


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« Reply #1 on: December 13, 2009, 02:27:26 PM »

Hi Steve,

My recommendation is a JBL unit:

http://www.fullcompass.com/product/304273.html

Take your PDM circuit with a LF bandpass-pass filter, and maul it.  Cheesy

Phil - AC0OB
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« Reply #2 on: December 13, 2009, 02:46:33 PM »

This is a very well regarded sub in the $700 price range, used by a number of people building "virtual" pipe organs, where solid well defined low end is essential.  Spec'd to 16Hz, but probably a bit less.  Spouse and/or girlfriend friendly size.

http://www.definitivetech.com/Products/products.aspx?path=Subwoofers&productid=SuperCube%20III

Grant/NQ5T
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Pete, WA2CWA
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« Reply #3 on: December 13, 2009, 02:57:36 PM »

These guys have a bunch:
http://www.parts-express.com/wizards/searchResults.cfm?srchExt=CAT&srchCat=620&CFID=13800677&CFTOKEN=49677502

I bought the SUB-120 HT some time ago and have been very happy with it. Doesn't break the bank and meets my woofing needs.

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« Reply #4 on: December 13, 2009, 03:59:36 PM »

Well.......big is better for subs IMHO.......
Trying to reduce the size of sub-woofer is like trying to use a short antenna on 160. U can make it work but it will be a compromise!

Now u folks know why Im single!!!!!!

Bill
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« Reply #5 on: December 13, 2009, 04:13:43 PM »

well said, bill... Cheesy
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WA3VJB
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« Reply #6 on: December 13, 2009, 04:22:49 PM »

Now u folks know why Im single!!!!!!

Bill

Because big is better ?

OH wait.
I understand.
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KC2IFR
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« Reply #7 on: December 13, 2009, 04:25:10 PM »

Paul............
Great return post.........LOL..........

I deserved that!
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steve_qix
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« Reply #8 on: December 13, 2009, 05:01:48 PM »

I'm allowed about 30 inches in height and about the same depth and maybe 24 inches wide.  That seems a "big" size for a sub, but maybe not.  I definitely don't want to compromise the low end response.  If I can't get down to around 10Hz, I probably won't bother  Roll Eyes

Hopefully, this can be achieved!!!!  I'm going to check out the products mentioned in the replies so far.  THANKS  Wink

Regards,

Steve
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KC2IFR
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« Reply #9 on: December 13, 2009, 05:12:12 PM »

Steve,
U are "allowed"......please explain......
Allowed by who?HuhHuh     
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flintstone mop
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« Reply #10 on: December 13, 2009, 06:50:24 PM »

Steve
UNfortunately pretty  is going to mean $$$$..........we had a discussion here recently about Man Caves.
My wife got a kick out of that. Doesn't understand it all, but knows that is my area!!

Fred
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« Reply #11 on: December 13, 2009, 06:57:35 PM »


Everything you know about subwoofers, Steve, is wrong!!

Check out the high Xmax woofers of today!

Parts Express has a good number of very high quality examples.

The "secret" Qt value is close to 4.0-4.5. With that Qt the "alignment" in the cabinet is "magic".
You want to download a basic (free) "box response" software and investigate the relationship between Qt, Fs and VAS vs. Vb WRT F3.

IF you use a corner, you will get significant LF lift, which is not entirely predictable, but is measurable. Be prepared for that.

These modern subs use high excursion and high power handling with optimized flux fields to get very excellent LF performance.  Expect to use a large high DF amp, in most cases. I would not opt for one of those "plate amps" myself.

Any commercial sub in a box that advertises "10hz" response is being somewhat optimistic, and it is unlikely that it will do that very loud, if at all. Typically the better ones use some sort of feedback from the cone to flatten the acoustic response.

I don't see any need to run in a corner unless you really need some LF boost, btw.

A 4th order LP active filter is a good idea. Marchand sells boards that you can easily modify to suit your needs and are inexpensive.

Depending on your home construction and WAF the ultimate solution is an Infinite Baffle configuration. That would use the floor, wall or ceiling as the baffle and the open space ("infinite") behind it. The advantage to that is that then the driver goes down all the way to Fs (free air resonance) rather than something higher when enclosed in a box, even a refrigerator sized one.

                               _-_-bear

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steve_qix
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« Reply #12 on: December 13, 2009, 08:12:07 PM »


Depending on your home construction and WAF the ultimate solution is an Infinite Baffle configuration. That would use the floor, wall or ceiling as the baffle and the open space ("infinite") behind it. The advantage to that is that then the driver goes down all the way to Fs (free air resonance) rather than something higher when enclosed in a box, even a refrigerator sized one.

                               _-_-bear


Hi Bear,

Thanks for the info on the subs.  I'll check this stuff !!  As far as an Infinite baffle - I just can't do it - I can't cut a hole in the beautiful (and very expensive) hardwood floors that are in every room of the house  Tongue   I don't know why.  It doesn't make sense.  But so far, I just can't do it.  Maybe if Frank (GFZ) does it first in his new beach place  Cool
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« Reply #13 on: December 13, 2009, 08:52:15 PM »

This could go on for ever......
Keep this in mind.......for sub woofers make the enclosure as big as possible.......no if's and's or butt's.
There is NO free lunch...........
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« Reply #14 on: December 13, 2009, 09:06:08 PM »

Velodyne. Haven't met a SW that can beat it.
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« Reply #15 on: December 13, 2009, 09:06:29 PM »

Bear, you are saying I could cut holes in the floor of my pier and beam house put the subwoofer speaker there?
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KC2IFR
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« Reply #16 on: December 13, 2009, 09:07:55 PM »

oh boy.........here we go........ Roll Eyes
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« Reply #17 on: December 13, 2009, 11:21:03 PM »

single guy here reporting in from the man cave -- can't you just take ur homebrew woof woof woofers and throw a sheet over 'em?  In't dat okay?    Fasten it with clip leads.

more important question -- what's to hear at 50 hz and below?  sound that low just shakes stuff.  hope you got a house made of steel and concrete.   Boogie down man.

Rob
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« Reply #18 on: December 14, 2009, 12:28:48 AM »

I had a 12" downward firing sub-woofer for several years and it worked great. Unfortunately, every time there was a long duration low frequency blast, the pets would run out of the room. I guess they could feel the vibration in the floor as they laid there.
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« Reply #19 on: December 14, 2009, 06:38:45 AM »

steve,
buy yourself a new hi-def TV and build a room/mancave in the basement, set your subwoofers up down there and it can be your own little escape.
when she yells down the stairs for you just crank up the volume "WHAAAT I CAN HEAR YOU"
 Grin

guess i'm with Bill on this one...  Wink
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« Reply #20 on: December 14, 2009, 09:59:19 AM »

Velodyne is a halfway decent commercial offering - it uses a form of feedback. With the advent of high Xmax and higher power handling speakers the design has improved, but not beause of any intrinsic engineering. I do't like downward firing subs for a variety of reasons.

Bill, yes, up to a point larger is better... ooops gotta go out more later.

Back...

Well another problem with the downward firing method is that the VC is pulled out the gap by gravity, and this gets worse over time, also the cone is high mass (making matters worse).

These days you can get surprisingly good LF performance from relatively small boxes due to the high power handling and extreme Xmax (not Xmas - Xmax = excursion) of today's drivers. So you can EQ a smaller box and get surprisingly good LF extension today, whereas some time back you'd have run out of output at LF.

Another nice idea is the EBS "Extended Bass Shelf" which uses a ported or PR design with the resonance of the port or PR set "too low", but EQ added to flatten the response down to that point - works well.

Steve, you can use a ceiling or wall too for the IB set up...

                        _-_-bear

Rob, 50hz isn't low enough. The low string on a standard electric bass is just above 40 Hz. Some players have electrics that go down to C below E, lower. Going flat to 35Hz is a pretty darn good design point, but there is an octave below that. What's down there? Pipe organs, big drums, Jurrasic Park sound track, Mickey Hart's percussion kit, and all sorts of neat things that make things sound big and heavy...

Patrick, yes an IB set up is a speaker in a floor wall or ceiling where the back end is "free air"  - facing outside is best, of course!  Wink    But keep in mind that the suspension of a standard speaker is designed to be vertical not facing down. So some care must be taken in the selection of a driver that faces up or down... the best choice would be something like an Eminence 15" pro woofer with a very LOW Fs, you can then ignore the VAS spec and only look at the Qt, which in a pro driver is low (ok for this application) and shove it in the floor or ceiling (up to an attic, for example - but keep the mouse and dust away with some window screening! That will give you flat response (or whatever the speaker does without EQ all the way down to the resonant frequency (Fs). So if you find a 15" high power pro driver with Fs = 23Hz it will go flat to 23Hz. Magique!



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« Reply #21 on: December 14, 2009, 11:59:29 AM »

Crap, I just put flooring down in the corner of the living room so won't be drilling holes any time soon. I do hace a pvc pipe in the wall to run wires to the basement.
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« Reply #22 on: December 14, 2009, 12:11:32 PM »


Frank,

If ur skilled at the art of woodworking, one can cut the nice new floor and make a setup that will be pretty much invisible when not in use to the wife's eye.

Two ways that i see... one is to make what is essentially a "hatch", you can actually use one of those nice stainless or brass hatch pulls that they use on boats, and that hatch will cover the speaker. Of course UNDER the hatch you will need some sort of attractive grating so that no one stands on the speaker... but that seems do-able. The beauty of this idea is that it is covered when not playing, and you open it on those rare occasions that you do play it. In fact the thing doesn't even need to be removed, it is sufficient to merely open it to a 45 degree angle, even facing toward the wall (away) so that it remains "pretty" is fine.

Way two is to make the cover over the speaker, the hatch, still out of the same material as the floor, but make it more or less 50% open, so that it looks like maybe a type of through the floor slotted heat plenum. A router with an appropriate round-over bit to dress the slots would do that trick nicely...

Fitted professionallly it will look seamless.

                           _-_-bear
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« Reply #23 on: December 14, 2009, 12:38:00 PM »

 "  buy yourself a new hi-def TV and build a room/mancave in the basement, set your subwoofers up down there and it can be your own little escape. "

Yeah, but, she'll come down and then get really loud...

Soundproofing is the next best thing?     A new topic....

klc
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« Reply #24 on: December 14, 2009, 12:58:24 PM »

Steve,  Will you take something used?   I get about 5 or 6 Subs through here a year.  I have a few in the other room. I will look at the brands act.. I know I have one Velodyne somewhere.

I have owned about 30 types and I built my own.  My favorite is the paradigm 10 or 12.  From someone that owns or has owned just about every classic speaker there was..  I like the small black paradigm's.   I also have a collection of old JDL, real b and Os and Advents.

Here is a picture of a subwoofer I designed and built.   The material is not plexiglass.  Its a type of material used at the Seaworld aquariums.  Its LF lucite  Its natural resonance is low. 

The subwoofer itself is an Earthquake unit. I chose this 15 inch woofer because of its thiele small properties (http://en.wikipedia.org/wiki/Thiele/Small).  I read though book and manuals for 2 weeks before finging this unit. It had exactly what I was looking for.

The base of this unit is Granite.  We had a Tile/marble house near us.. I rode my bike down and talked to one of the marble Craftsment from italy.  He made it for me at a great price.  The bottom includes a cutout for the coil.

The Standoffs are also lucite also.  Hand cut.  I rented a Studio that had an anechoic chamber.  I did this afterhours and paid very little.  I played pink noise through the sub and then used a real time analyzer to record the output off the sub.  I came prepared with 7 different lengths of standoffs.  I decided on the length in the picture. 

I made several of these one summer.  I kept this one as it was the first and its flawed.  I overtightened some screws and made some hairline cracks. The edges on the box construction are not perfect either.  You have to inject the chemical in each seam with a seringe.  If you dont do this correctly, you might get a run or two.. Smiley

Did I mention I was 15 years old when I built this?  I did this as a summer project! I have kep this thing all these years.. Its not actualy in use now..  We had a transformer blow up in the hood and the Subwoofer amp never came on again.. The relay just clicks and thumps the speaker over and over.. I will have to fire it back up someday.. It ROCKS the entire house.

CLark



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