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Author Topic: The O so impossible 20hz!  (Read 13614 times)

Mark Seaton

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Re: The O so impossible 20hz!
« Reply #20 on: February 01, 2006, 06:14:38 pm »

Michael Fraioli wrote on Wed, 01 February 2006 13:50

well that dont sound half bad these lab subs are sounding better and better so 20 hz at a 2 meter listening position at around 115db round about with an enclosure no bigger then 36" wide 60" tall and 36" deep how many subs what size and what series would i need? and what kind of amp and eq do you recommend with it? do u have specs or links to any of this? and any idea how to build the box maybe a cad drawing or some thing hand drawn and scanned in so i know how to build this beast? thanks antone big help!


Hi Michael,

First, your question is relates more to home theater than to pro-audio.  In the confines of your small room, it won't be hard to get pretty serious output to 20Hz.  You did mention a budget of ~$1200?  That does start imposing some limits and narrowing things down.  There are a couple of subs from online manufacturers which will deliver decent 20Hz output for that sort of money.  SVS's PB12-Plus/2 or Hsu's soon to be released VTF-HO would likely be the easiest routes, although 2 or more of the SVS cylindar subs might also fit the budget.

You have also talked about DIY.  If you are willing to build, and especially if you are willing to make a decent size box, that will certainly give you the most bang/buck. Parts Express have a variety of 12 & 15 inch drivers in their Dayton family that could work great for very reasonable price, and they even have some nice plate amps for startlingly cheap $/W.

For what you describe, use multiple drivers so you don't have to worry about power handling.  From there, you could go with 2-8 drivers depending on your fancy.  Best bang for buck would be a pair of 15" drivers in the right size box.  If you have to keep the size down, most of the 12" drivers will be beter suited to what you want.  In a small room like you have, I would lean towards 4 12" or 2 15" drivers in sealed boxes with appropriate EQ.  Having Smaart you are a long way ahead of many others making the EQ option much more useful.

I suggest you look through this forum and see if some of the projects there give you some ideas.  If you can make some decisions as to what size and costs you can live with, I'm sure they can help you out, and I swing through when I can as well:

HT Guide Forum: Mission Possible DIY

Hope this helps.
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Mark Seaton
Seaton Sound, Inc.
"Make no little plans; they have no magic to stir men's blood..." - Daniel H. Burnham

Dave Rickard

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Re: The O so impossible 20hz!
« Reply #21 on: February 01, 2006, 06:48:10 pm »

Michael Fraioli wrote on Wed, 01 February 2006 12:55

but i dono if would help u in coming up with a design for me if ud be so kind...or maybe there is a design already out there?

Post here.  Good guys, good advice.

http://www.pesupport.com/cgi-bin/config.pl

Dave
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Dave
Yorkville dealer

"The wrong piece of gear, at the right price, is still the wrong piece of gear."

"If you don't have good stuff at each end of the signal chain, (mics and speakers) what you use in between is just turd polish."--Dave Dermont

Michael Fraioli

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Re: The O so impossible 20hz!
« Reply #22 on: February 02, 2006, 09:06:03 am »

you keep reffering to going to home audio but i have yet to find any home audio products that giuve you any sort of specs that are worth a shit. i have an infinity alpha1200 right now it says it plays down to 29hz...umm yeah maybe at -10db but they dont even give you those type of specs so its a shot in the dark thats y i think pro audio is the way to go so i can see exactly how the sub will perform before i waste my money on it. im seriously considering antones ideas and goin with the lab subs they are in my price budget not to large of an enclosure and from the specs he had mentioned they sound what i am looking for now i just need to have some design so i can build the cabinet
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Dave Rickard

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Re: The O so impossible 20hz!
« Reply #23 on: February 02, 2006, 10:56:40 am »

It seems like you're ignoring good advice because it's not what you wanted to hear.  

First the suggestions are too big, now they're too expensive, yada, yada...  TANSTAAFL!!! (google that)

Go to the Parts Express forum and ask.  Ask for measurements, they've got them.

Dave
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Dave
Yorkville dealer

"The wrong piece of gear, at the right price, is still the wrong piece of gear."

"If you don't have good stuff at each end of the signal chain, (mics and speakers) what you use in between is just turd polish."--Dave Dermont

Mark Seaton

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Re: The O so impossible 20hz!
« Reply #24 on: February 02, 2006, 01:56:08 pm »

Michael Fraioli wrote on Thu, 02 February 2006 08:06

you keep reffering to going to home audio but i have yet to find any home audio products that giuve you any sort of specs that are worth a shit. i have an infinity alpha1200 right now it says it plays down to 29hz...umm yeah maybe at -10db but they dont even give you those type of specs so its a shot in the dark thats y i think pro audio is the way to go so i can see exactly how the sub will perform before i waste my money on it. im seriously considering antones ideas and goin with the lab subs they are in my price budget not to large of an enclosure and from the specs he had mentioned they sound what i am looking for now i just need to have some design so i can build the cabinet


The majority of retail manufacturers are just starting to catch up with real performance quantification.  I've personally been quite involved toward that end on the home theater front since I started working with Tom Danley maybe 5 years ago now.  Head over to AVS Forum and see all the discussion about measurements and real performance in the Subwoofer forum.  The hi-fi audio sector is still blissfully ignorant of what's happening with the serious home theater installations.  Unfortunately the jewelery like hi-fi stereo market gets more press.  Serious contractors, installers and designers are operating on a level that you will never be exposed to in most retailers spare a few.

For examples of real measurements, check out the article that really led the pack:  Way Down Deep, Ultimate AV Magazine - Keith Yates

Keith designs some of the highest performance home theaters in existence.  He did this article more as a survey to collect more data for his design work, and offered to do it as a 3 part article with Ultimate AV just before they went web only.  There were also 2-3 parts in Home Theater Magazine on some less expensive subwoofers.  Among probably a dozen more very highly respected people, both Tom Danley and myself gave input on the test methods.  A little input from everyone was taken into account, although there is a limit to how much data they could present in print and what the public was ready to digest.

When I provided the link to the HT Guide at the end of the last post, realize that is hardly a "hi-fi" or just home theater forum.  Those are serious DIYers, some of which employ 12, 12" subwoofers or 18, 15" woofers in large infinite baffle designs.  They value measurements and expect real performance, even if a few have slightly esoteric tastes.

The SVS products currently offer one of the best alternatives to DIY for under $2k.  They were in fact spawned from two DIYers building sonotube based subwoofer designs.  In a few months I will have a first subwoofer in production as well that will be quite potent with a pair of sealed 15" drivers and ~1500W.  While I feel it will offer a great value, it will be above your intended price range at $1995 just as the DTS-20 (I had some input on that package & design goals before Tom made it reality - originally conceived for Home Theater) is out of your intended price range.  All of these have a good deal of performance data available with a bit of searching.  Generally much more useful and meaningful information than you will find in common professional data and spec sheets.

The founders of SVS, myself, Keith Yates's report linked above, and a handful of others have been pushing reviewers to expand the data provided.  We also can't forget the past reviews done by Don Keele and Tom Nousaine who both provided insight into the real performance of subwoofers.  More recently a member of some of the forums I mentioned had started measuring and posting his results on the forums.  His methods have evolved, and he was then asked to be a reviewer for Secrets of Home Theater and Hi Fidelity, and online publication.  Check out how far his current reviews have come:  Product Review: SVS PB12-Plus Subwoofer

If you are inclined towards the DIY realm, and you don't put a dollar value on your time invested, with a little research you can easily exceed the performance of most anything you can buy for 2x the parts cost. You obviously trade off the certainty in what you will be getting unless you copy the design of another.  If this is the route you are interested in, start looking at how large a box or boxes you are willing to deal with and ask for options with that available volume, room size, and general budget range.  If you follow some input from the forums, it is unlikely you will not be very impressed.

Regards,
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Mark Seaton
Seaton Sound, Inc.
"Make no little plans; they have no magic to stir men's blood..." - Daniel H. Burnham

Gareth James

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Re: The O so impossible 20hz!
« Reply #25 on: February 02, 2006, 09:27:04 pm »

Michael, I don't think you've thought this through to be honest...

You say the Danley DTS-20 is too tall at 7', but a LABsub would be ok... The DTS-20 is tall but has a small footprint at 17" square, you could stand it in a corner or lay it down the side of a wall as suggested.

The LABsub is likely to fill most of your room by the sounds, its footprint is around 4 times that of the DTS-20 and no amount of moving it round is going to change the fact it takes a lot of space.

You also mention you are looking to spend no more than 1000 dollars on amp and sub, in which case i don't think the labsub or dts-20 are within your reach.

I would definitely recommend looking at infinite baffle designs within your budget area.

Good luck!
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Antone Atmarama Bajor

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Re: The O so impossible 20hz!
« Reply #26 on: February 03, 2006, 06:24:17 am »

Not a Lab sub

A sub built with the LAB 12 Driver.  Its a great driver for the price.

     As Mark Seaton. pointed out Dayton also makes some decent inexpensive drivers.  I think one of them measures almost the same as the Lab 12 and is cheaper.  I would model it against the labs but my hard drive with all of my modeling software on it died so until I reinstall Its not happening.

    I'm just a babe in the woods when it comes to a lot of speaker stuff.  Mark and many others here have a bit more Real world Experience than I.  So their advice is more than valid.  

    I have never personally investigated an (not so) infinite baffle design but not everyone has the option to cut holes in their walls or Ceiling.  And I don't think efficiency, Linearity of response, power bandwidth, or phase response/group delay is improved so why would you do it?  But I don't know this so prove me wrong.

   
    I wouldn't say that the Sealed Lab 12 box is Pro Audio even though the driver was designed for a very specific pro audio application.  It would take too many to reach pro SPL levels to be practical.

    I have not built the sealed box that I have been talking about yet but I am about too.  I have done the modeling I can give internal volumes and basic dimensions.  I choose to build differential so it makes design a little more cumbersome I suppose.  But you don't have too.

    Did you say you wanted to achieve 20Hz at 115dB @ 2 Meters?  That may take 4 sealed Dual 12 Cabs.  Depending on your room gain.  As you loose 6dB every doubling of distance or is it 3dB indoors?  Though you may have 12dB per octave room gain starting at 40Hz that means 20Hz will be 12dB louder at 1 meter Plus the 1/4 space loading gain.  So some of it depends.

    In an infinite room with a perfect wall floor intersection 4 sealed dual Lab 12 subs you would have 125dB RMS 20Hz @ 1 Meter.  Of course no room boundary or speaker is perfect.  And you will probably get more gain @ 20Hz depending on room.

    Anyhow I'm tired MSG me and I'll try and get you the specifics.  Also read the forums that Mark linked you too.  And the infinite baffle stuff.

    I'm not sure which 15 Mark suggests.  The Adire is pretty cool for some applications.  The Adire 18 is cool too but les maneuverable.

    Educate your self the best you can and make an informed decision because noting can be more important than rattling your neighbors teeth!

Antone-

   
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Antone Atmarama Bajor

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Re: The O so impossible 20hz!
« Reply #27 on: February 03, 2006, 06:39:01 am »

     Not to toot my own horn but the BS-212's (Pair is ~ same volume as Genelec) that I built using the lab subs outperforms the Genelec @ 20Hz by several dB.  Genelec and the Contrabass are the 2 best reviewed from what I remember.  The contrabass is certainly the most efficient for its size though.  

    I will have to do my full power sweeps but I suspect the
BS-212 has a much lower THD across the board too.  Maybe I should send Keith a pair.  But I already know that Tom has everyone licked with his DTS-20 (I do want to see the THD and group delay/phase data though).

    Unfortunately my nice large open field is now a Swamp so I can't do any good tests until it drys for a month or so.

    Too bad they're too big for the average living room.

Antone-



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Michael Fraioli

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Re: The O so impossible 20hz!
« Reply #28 on: February 16, 2006, 08:14:40 am »

ok i decided i am gonna go with the lab 12's and that bs212 i think u were talkin about sounds good but i only want half that...so basically 2 12's in the same type of enclosure you currently have....what amp and eg do you recommend and do you have any sort of drawings you could send me showing how you built it so i can more easily replicate your design thanks again guys for your help
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Antone Atmarama Bajor

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Re: The O so impossible 20hz!
« Reply #29 on: February 16, 2006, 05:13:50 pm »

     Yes I do have drawings  The are currently in auto cad.

    I'll try and set one up for you (and the lab community) with all of the dimensions.  

    I don't know if I should try and set things up to prevent the design to be used by others for profit.  

    If anyone has any idea how I set up a limited public domain copyright situation let me know.

    The BS-212 is rather large still a sealed sub would need a little more support equipment to flatten its response.

    As far as amplifiers go.  I'm not sure what to recommend I'm trying to figure out if I'm having Issues with my Alesis Matica 900 I get some funny popping happening while playing Bass through them or LFE signals.  I've been having good results with the AB amplifier we have in my shop I've never made the drivers pop or chunk and thunk with the AB.  But I need to make more thorough tests.  I could just be overexcurding the driver.

    Hopefully I can get everything ready in the next couple of days.

    There is much room for improvement.  I didn't to any butt joints everything is screws and glue blocks.  I used wood flooring adhesive so the joints would maintain flexibility while working with it.

    Get you the info soon.

Antone-

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