Clueless in Seattle but curious

[vasubandu]

Greetings everyone, my name is Matt Davis and I live in Seattle.  I am newly back to audio after a decade away, and my how things have changed. I had a paradigm MIllenia system, which I think is based on 4-inch drivers, and it never really filled the room.  I now was a Klipsch system with 8 inch woofers all the way around, and it is much better.

My subwoofer is a 2004 SVS PB2 Plus, which I quite like, but I a coming from a Paradigm SW2200.  SVS also made a B4 Plus with 4 12-inch drivers, and when one came available, I was ready to jump on it, but all of my audio friends jumped on me and said that 15-year old subwoofers were not the way to do.  So I gave in and looked at what was new, and I was very attracted to the SVS round subwoofers.  And them someone said that I should make my own, and that looked easy enough.  My observation was the was have gone to bigger and bigger drivers, but that enclosure size has not really changed, from which I concluded that enclosures today must be undersized.  I decided to make a subwoofer with the appropriate capacity, and what would be the fun of that if it were small. SO I have been designing a ported tube sub for 2 SI HS-24 Mk II drivers, each of which is rated for 16-20 cubic feet.  I wanted to stick with the tube shape, which led to a column 3 feet in diameter and 6 feet high.  Everyone said to use Sonotube, but I decided instead to use curved 5/8 inch plywood.  It is easy enough to get half circles and join them.  I never could live with the idea of a cardboard subwoofer, and I am not sure I would want to put a 115 pound driver on top of one.

And then I came across Eric's Infinite Baffle Subwoofer on the Bucknell.edu website, which led me here.  And now I am wondering if my massive column would be a foolish alternative to an IB sub. It helped that Eric went from a Sonotube sub to his IB.  He Sonotube differs in many respects from my plans, but it at least gave some comparison.

My home theater room is not that large and should not require 2 24-inch drivers.  It is essentially 24x15 feet with the TV at the left end of one the 15 foot walls.  The right end of what wall has a 3x10 nook out so the wall that the TV is on is actually 18 feet long.  Because of doors and cabinets there really are no alternatives.

I hope that I can gather enough information here to decide whether to change my my plans and make an IB subwoofer instead.  One of my questions is whether that would make ditching the expensive SIK HS24 in favor of something else.  I have an Eminence MFW-15 sitting around and could get another easily enough I assume but I have not seen any yet.

I have another question that probably goes beyond bizarre. As a result of a part project in the LED lighting area, I have an established account with Alibaba and a good history of purchasing significant quantities of materials. That tends to get me in the front door with vendors and allows me to get samples.  A company called Fante (and probably lots of other things as well) has an extensive list of speaker products, many of which look like knockoffs, but sometimes those knockoffs are better than the original.  Among other things, they have 2 32-inch subwoofer drivers.  I can get an evaluation paid for $900 delivered to Seattle.  I had been thinking of seeing how they were in an open baffle system, but now this has me wondering if a 32-inch IB subwoofer would be worth thinking about.  

If anyone made is through all this, I would welcome any thoughts or suggestions.

[ThomasW]

Hi

How about posting a copy of the floorplan and some pics of the room?

As for 32" drivers, these are best left to fantasy unless you have access to a forklift, chain hoists and other materials used to pull and insert V-8 motors. Since it's just about as easy to build with a V-8 as it is to manhandle 32" drivers.

Also how would you get service for the Chinese driver in the event of a driver failure?

[vasubandu]

This is my room layout.  Will edit with pics tomorrow.  The room has 7 foot ceilings with 12 inch ceiling tiles vintage 1964.  The floor is bamboo, but there is a 13x17 rug in the TV area that covers the entire area.  The walls are covered with a grasscloth wallpaper.  When it was installed, I noticed that the room echo from walking across the floor was gone, but I doubt that it has much more effect than that.


imgur.com/a/lPExc


My system has an Integra DTR-506. receiver that I bought used too cheaply to change, an Outlaw 7700 amplifier, a Klipsch RC-7 center, RF-5 fronts that have RC-7 tweeters and crossovers making them the equivalent of RC-t centers except for the enclosure, RS-7 surrounds and the two RC-7 donors as back surrounds with the RF-5 tweeters and crossovers.  All told it is pretty tame system but a huge step up from the Paradigm Millenia and its 4.5 inch woofers that preceded it.  The subwoofer is an ancient SVS PB2 Plus that likewise is a huge step up from the Paradigm SW2200 that preceded it.  The PB2 Plus lacks clarity and crispness, but it provides plenty of bass and vibration. 

I would like to make another upgrade to larger woofers, not for greater volume, but for what I perceive to be a fullness to the sound. With the Paradigm speakers, it felt like they were straining to reach me, and I was straining to hear them.  Now if feels like the sound fills the room.  Hard to describe.  Klipsch had the sense to make an awesome series of speakers called CF, with a CF-1, Cf-2, CF-3 and CF-4.  Each had a larger pair of woofers, 6.5, 8, 10 and 12 inches.  Many people have said that the CF-4 is one of the best speakers Klipsch ever made, which explains why the whole series lasted 2 years.  If I could ever find a pair or 4  of CF-4 with another for the center, I would be set, but they are hard to find. The theoretical max for me would be a set of JTR Noesis 215RT speakers, but they would be under-used.

None of this remotely explains a 32 inch subwoofer.  I guess I would analogize to my Paradigm Millenia speakers.  Great speakers, but just not enough presence to do anything. I have read many times how much people love the sound of open baffle subwoofers, but how they fall off too high. So my question quite simply is whether a 32 inch open baffle subwoofer would reach farther down by virtue of its size. Not by pushing the driver or playing it loud, but across the board and at lower volumes.  I have absolutely no idea what the answer is, and perhaps there are equations that would tell me, but my instinct is that it would fall off lower.  And I think that to find out, I would need to make a huge leap in size, not 15 to 18 or even 21.  A 32 insuch subwoofer would have over three times the area of an 18, and I don't think that 3 18 inch subs would be the same.

As I said, I very new to all this, so I am making some dangerous assumptions.  If I am dead wrong or treading old water, I would love to have someone hit me over the head with the facts.  But if it is an unanswered question or an interesting exercise, why not give it a try?  

Oh an service for the driver?  I have had luck with service for some things I got in China, but it is hit and miss, mostly miss. I would be on my own.

[ThomasW]

So my question quite simply is whether a 32 inch open baffle subwoofer would reach farther down by virtue of its size. Not by pushing the driver or playing it loud, but across the board and at lower volumes.

There are multiple variables that enable a driver to play low in a room and the size of the driver isn't necessarily the predominant factor.

Drivers have an Fs =resonant frequency. People tend to think that's the lowest frequency a driver can play, that's not the case. Using EQ a driver can play well below it's Fs.

So what does all this mean?

It means there are numerous things that make a driver "good". Diameter alone isn't the most important factor to consider when deciding on which driver is best for a given install.

For example, look at all the test data provided by PE

www.parts-express.com/peerless-by-tymphany-stw-350f-188pr01-04-15-high-power-subwoofer--264-1652

And compare the above to the specs on the 32". The above is an extremely sophisticated driver design, the 32" is more or less a generic driver.

[vasubandu]

Reaching particularly low is not even my goal.  I am probably mistaken, but my innate sense is that subwoofer fans are artificially pushing the frequencies down with tricks.  They seem malcontent with the sound that their drivers actually make. I find that particularly odd given that we are talk about a range where people cannot hear.  Is there really a difference between 12 Hz vibrations and 18 Hz?  Would be interesting to do a blind test with a single tone and ask people to call the frequency.  

So I am more looking for an organic approach that lets the driver express itself instead of yelling into a box.  Whether that would be open baffle or infinite baffle I have no idea, but what I have seen of IB looks simple and direct.  It looks strange at first, but it makes sense, and I understand it to just be the drivers doing what they do. A lot of my thinking was formed when I was looking at open baffle designs, and I think I still have some confusion between them.

The n=bottom line is that I have essentially a  25x15 foot room with 7 foot ceilings.  My 2004 PB2 Plus already shakes things around enough, but it is muddy.  So I do not need to set the world on first, just find something that produces good sound and satisfies my sensibilities. I like what I have seen here in terms of approach and a desire to have things make sense.  I hope I can stick around and really get to understand this.

[ThomasW]

The idea behind an IB sub is to have as little as possible between the bass signal and the listener. That doesn't mean we don't use EQ. All subs require EQ either to flatten the response curve or boost the lowest frequencies. We're lucky these days because modern signal processors are very low distortion units.

Yes there's a lot of 'ego' involved when the focus is on reproducing signals below 10Hz (unless one has the budget to buy a rotary sub) The rotary sub is the only sub I've heard where it's actually possible to distinguish single Hz differences, ie 5Hz vs 6hz vs 8Hz etc.

The other thing to remember is that having a 'clean' sub is 1/2 the project, the other half is using room treatments (bass traps, diffusers), along with signal processing to help mitigate the effects of the room

[vasubandu]

Thanks again, I have been reading what I can find about infinite baffle subwoofers, and a lot of it seems to be inconsistent.  I had understood it to mean a subwoofer design in which the drivers face into rather than out of the enclosure. I still am not sure exactly what that make a difference with omnidirectional sound, but I am still learning.  Then I read references to subwoofers that are in walls with a room behind being IBS even though the driver faces into the TV room.  If that arrangement actually provided all the same benefits, I may have an idea situation, although the room is 5x12 with 7.5 foot ceilings (450 cubic feet).  In what may or may not turn out to be related, I have used my China contacts to order a pair of 32 inch drivers.  They are reported to be of good quality but we shall see.  If one of those in my wall would make sense, that would simplify a lot of things.  If you have any thoughts, I would appreciate them.

[superfrog]

You will have to be the deciding factor on that one. I do have 2 si ht24s in an ib in my theater. These are the original si ht24 that are still available for 699 each. Yes, these would be perfect in your room. They are awesome in my roughly 14x14x 8 theater. However they are articulate and clean and I have not done anything except measure and my mic is a cross spectrum umik1 calibeated to 5 hz and these dig below that without external eq to make them do so. I have 1800 watts on each sub in a single manifold and people are amazed when they are in the theater how tactile and enveloping the bass is but not overpowering the rest of the system. These subs have absolutely messed my car audio taste up. I have been searching for a sub that produces bass like these to no avail. I used ib in previous systems but I have an suv now and I can’t. Just because you have a 32 inch sub doesn’t mean anything. How they are made etc is everything. Also, have you considered how big the manifold will have to be. You can’t just slap that thing to a wall and expect great things. The moving mass of that sub is enormous and the wall will have to be braced with at least 2x8s. The 24s are simply amazing subs. Personally, why would you buy from China and have no idea what your getting verses buying from a small company here in the US that’s known for building great quality subs. A person on another forum did what you are doing and got a bunch of 24inch piles of crap trying to save some money. Oh well. Good luck with that. Let us know what happens