Subs again! boxes vs OB

drphoto · « **on:** 30 Oct 2008, 04:55 pm »

When I get my Merlin TSM's back from their upgrade, I'd like to give them a firm foundation. Though I listen to jazz and even opera, I basically like to rock, and rock's gotta thump. But of course, I don't want 'boom car' bass. Gotta be clean and fast enough for the Merlins.

Now the first and easy choice would be one of the offerings from our friends here, like Danny's version of the Rythmik, or one of Mike D's designs (ACI)

But then I read about all the advantages of 2 (or even more) subs and that option gets out of my soon to be broke pharmacy student price range.

So I start thinking about OB, (which seems to have some room interaction advantages), plus they'd be cheap and easy to build. I have an Adcom GFA-555 I'm not currently using for power, and could get a Behringer crossover just for the low pass portion.

If this has been covered somewhere else, please point me to the right thread.

My current sub is a Mirage BPS-150i, and it's a wimp. Plus it doesn't have fully adjustable phase, only 180º switch.

thanks for any suggestions

Bob in St. Louis · « **Reply #1 on:** 30 Oct 2008, 05:05 pm »

My vote is for OB, but if you've got the ability, Infinite Baffle creates a VERY nice tactful thump in the chest at all volumes (including amazingly low SPL) without the muddy boomy 'car bass' you refered to.

Speaking of your "soon to be broke pharmacy student price range", what is your price range?

Bob

drphoto · « **Reply #2 on:** 30 Oct 2008, 05:33 pm »

Hey Bob, thanks for the reply. I'd say $1K total. Of course, the less the better. Doesn't IB require a basement or crawl space? My rig is in a balcony overlooking my photo studio.

zapper7 · « **Reply #3 on:** 30 Oct 2008, 07:08 pm »

I put together an IB system for $1000.

It includes 4-15" drivers, 2 wood manifolds, 2 pro amps, and a dbx xover. I bought them all used for that $1000.
Absolutely the best move for bass I ever made. I had Velo, Earthquake, Mirage, Def Tech, you name it, bass search over.

I did put mine in the floor, but an attic, garage, any open space adjacent but not in the room. You would hear the bass in that adjacent space as well.

ifinitelybaffled.com, or something like that is the best for info on this type of bass.

Enjoy

Bob in St. Louis · « **Reply #4 on:** 30 Oct 2008, 07:17 pm »

Yes, it does require the entire rear wave to exit, or "vent" into an area other than the listening room.
If your balcony has an attic over it, a big enough closet^* in it, or any other interior wall, or floor that would allow access to the back of the drivers, it can be done.
I recall a thread of yours recently, if memory serves, this is a HUGE room. Much bigger than the average listening room isn't it? Hopefully smarter IB guys will chime in, but I believe I.B. would be one of the most efficient at filling a room THAT size with clean, tight bass.

^* The common school of thought for an acceptable "minimum" size (in cubic feet) requires it to be 10 times the Vas of all drivers involved. Although, my rig at between 4 to 5 times Vas of the drivers sounds amazing. If it's supposed to sound better than this.....wow!

Here's the Cult of the Infinitely Baffled Mr. Zapper spoke of.

And $1,000 for an IB is definitely do-able.

Bob

chgolatin2 · « **Reply #5 on:** 30 Oct 2008, 07:57 pm »

Check out this well respect "American Company" http://www.ascendacoustics.com/pages/products/subs/subintro.html

isaacc7 · « **Reply #6 on:** 31 Oct 2008, 01:46 am »

You might want to check out Linkwitz's dipole subwoofer http://www.linkwitzlab.com/woofer.htm. I haven't heard it, but it looks like it would go very well with dipole speakers and share their strengths....

Isaac

MJK · « **Reply #7 on:** 31 Oct 2008, 02:00 am »

Consider a Goldwood 18" woofer in an H frame. Bass into the mid 20 Hz range, big and powerful in a relatively small package. Simple concept, easy to build, and the cost is under $300 per pair. These things can shake the house when required while still being very musical.

http://www.quarter-wave.com/Project08/Project08.html

Martin

Bob in St. Louis · « **Reply #8 on:** 31 Oct 2008, 03:20 am »

Drphoto, some opinions may change when they discover the shear cubic feet of your room.
Could you refresh the memory on exactly how big the room is?

Bob

drphoto · « **Reply #9 on:** 31 Oct 2008, 10:58 am »

Hey Bob, the sound system is in a balcony that is 20x25x8 overhanging a room that is 60x20x20 (which includes the balcony)

Could the woofs go in the half wall of the balcony and vent into the large room? Or does that go against the whole idea of IB, that the rear wave needs to be 'trapped' in a separate room. I suppose if they were in the half wall, I'd have a giant OB, rather than true IB.

W/ IB installs, do you run into issues of the whole wall resonating?

I'm not sure if I misunderstood Isaacs reply, but the Merlins are not dipole.

I'll try to post a pic of the room later today.

playntheblues · « **Reply #10 on:** 31 Oct 2008, 11:16 am »

Here is an interesting design
http://www.tektondesign.com/openbaffle.htm
And here is one on ebay, the price seems rignt

http://cgi.ebay.com/Tekton-Design-12-inch-Open-Baffle-12-Subwoofer-NEW_W0QQitemZ250316746923QQcmdZViewItem?hash=item250316746923&_trkparms=72%3A1240|39%3A1|66%3A2|65%3A12|240%3A1318&_trksid=p3911.c0.m14

EARGASM · « **Reply #11 on:** 31 Oct 2008, 01:36 pm »

All I can say is my "SUB CHASE" is over! GR Research has a paper cone version of the 12" Rythmik Audio Direct Servo Sub that is nothing short of stellar. So fast and controlled... The OB version has all the bass without loading the room. I have (3) of the FR 12" in a "W" baffle setup working right now. Just love it. Love it!

GR has it in 3 versions. 4 ohm, 8 ohm and FR for open baffle configurations. You can dial the amps in to play flat pretty much to 20 HZ. Sincerely outstanding!

TomS · « **Reply #12 on:** 31 Oct 2008, 01:45 pm »

Quote from: EARGASM on 31 Oct 2008, 01:36 pm

All I can say is my "SUB CHASE" is over! GR Research has a paper cone version of the 12" Rythmik Audio Direct Servo Sub that is nothing short of stellar. So fast and controlled... The OB version has all the bass without loading the room. I have (3) of the FR 12" in a "W" baffle setup working right now. Just love it. Love it!

GR has it in 3 versions. 4 ohm, 8 ohm and FR for open baffle configurations. You can dial the amps in to play flat pretty much to 20 HZ. Sincerely outstanding!

Eric - love to see a pic of your 3 GR Servo subs in the "W" OB setup aa

zybar · « **Reply #13 on:** 31 Oct 2008, 01:52 pm »

Quote from: TomS on 31 Oct 2008, 01:45 pm

Eric - love to see a pic of your 3 GR Servo subs in the "W" OB setup aa

Me too!

I am thinking of trying to build a few for the HT this winter.

George

drphoto · « **Reply #14 on:** 31 Oct 2008, 01:55 pm »

Yeah Eric, show us a pic! Thanks for your post. This might be the ideal solution, sound wise, as well as price wise.

EARGASM · « **Reply #15 on:** 31 Oct 2008, 02:05 pm »

Hey Guys,
The housekeeper is here is morning. I'll post some pix of it this afternoon. Wife will kill me, or worse, if I post pix of a dirty home.

Bob in St. Louis · « **Reply #16 on:** 31 Oct 2008, 05:17 pm »

Quote from: drphoto on 31 Oct 2008, 10:58 am

Hey Bob, the sound system is in a balcony that is 20x25x8 overhanging a room that is 60x20x20 (which includes the balcony)

Could the woofs go in the half wall of the balcony and vent into the large room? Or does that go against the whole idea of IB, that the rear wave needs to be 'trapped' in a separate room. I suppose if they were in the half wall, I'd have a giant OB, rather than true IB.

W/ IB installs, do you run into issues of the whole wall resonating?

I'll try to post a pic of the room later today.

- I don't believe the rear wave should enter the listening space at all. Despite the fact your room is SOOOO huge, it's still in the listening room. I hope I'm corrected if I'm wrong, but I doubt it will be as efficient as it should be if it was separate. Otherwise, yes, just what you said about having a giant OB. Which, now that I think about it might be interesting. Kinda of a hybrid OB/IB thing. Hmmmm

- Regarding the wall resonating. Yes, if they're bolted straight to the wall, the drivers will try their best to make the wall move, just like the cones. {Remember, for every action there is an equal and opposite reaction} It also depends on how you build the IB structure. If you build it like a five sided box (one end open for the "throat"), the drivers movements wil cancel each other. If you build what looks like a OB 'array' of drivers and mount them in a wall then they will all act together to try their best to shake your wall apart.
The way I did mine was to make the box extremely ridgid, solid enclosure, but sealed against the wall/floor/ceiling with a thick foam gasket to cushion the vibration. That way the wall won't enter the picture, acoustically speaking. Plus, I've got two drivers 'pushing' and two drivers 'pulling' (but wired to work together).

- I'd love to photo's of the room! aa

Bob

drphoto · « **Reply #17 on:** 31 Oct 2008, 06:47 pm »

Here's a quick snapshot of my listening area. I didn't feel like dragging out lighting equipment or even a tripod to make a pro quality shot.

Those are the Onix Ref 1's that are standing in for my Merlins, which are back at the factory for an upgrade. The boxes on the top of the rack and the second shelf are the Stan Warren Aiwa XC-35/MSB Dac combo. Not the last word in transparency but very nice analog like sound. On the left is my pride & joy, a '57 Strat reissue, which of course is my avitar. On the floor is Buddy.

I'm thinking about putting everything in the corner, where the crazy lamp is located, basically rotating everything 45º left. Not only would this look nice, it might sound good too.

zybar · « **Reply #18 on:** 31 Oct 2008, 07:15 pm »

drphoto,

Can you take a picture of just the subs?

Thanks,

George

Bob in St. Louis · « **Reply #19 on:** 31 Oct 2008, 07:24 pm »

Oh ok. Now I've got the picture.
OB most definitely. No doubt about it.
I thought you where trying to fill that ENTIRE space with sound, not just the balcony.

Yes. Open Baffle. aa

Bob
p.s. That's a couple nice racks you have by the way......Both of them.