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Old 12th July 2012, 12:48 PM   #21
DrDyna is offline DrDyna  United States
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Quote:
Originally Posted by john k... View Post
There is another issue with IB bass that should be considered. It is ofter discussed that OB bass, or dipole bass, doesn't excite room modes ascross the room or in the vertical direction. The thing is, that can be an advantage for a single woofer. But if you go IB and use 4 woofers you can (should, IMO) position the woofer so that two are 1/4 of the room height off the floor and two are 1/4 of the room height from the ceiling. In the horizontal direction there should be two woofers 1/4 of the room width from the left wall and two 1/4 of the room width from the right wall. In this manner many of the lower frequency modes in the vertical and horizontal directions will either cancel between woofers or not be excited at all. Axial modes in the lengthwise direction will, however, be excited to the maximum with wall mounted, IB woofers, but this can be countered by correct choice of seating position. But you are limited to a single row of seats for best bass.
This is diamonds, thanks John. One of the things I had been thinking about is where I'm actually going to mount the subs. I was planning 2 fi ib318s but it looks like I might be better off with 4 of them.

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However you are making a home theater and not setting up a dedicated stereo music system. I would think the video based application ( unless it is mainly for music video's !) will work very well with IB's.
You do not have much to do to get your IB going. So do it ! If you find it great then stick to it until you get to hear a dipole and determine if that is required for your application.

Going dipole now when you are almost finished with the IB doesn't seem to make sense. Starting on dipoles will lead to much more time spent and MUCH more testing and added parts than what's going on now.
Well, my plan originally was to just do IB subs as an addition to some of my existing subs (I love effortless, extended bass) and the idea of trying some of my main speakers in the same arrangement was an afterthought that popped in my head. The idea to compare it to a dipole came about while I was looking at Troels' page and his OBL-11, considering it's almost the size of a wall anyway, when there's 2 of them together. I realize that the IB being closed wouldn't be dipolar, so a lot of his description of the sound probably wouldn't apply quite the same, except for "there's no box".

It was more like "well, in a few months I'm going to be putting subs in that wall, I wonder if the benefits of that would translate into the main speakers as well....and it would look drop-dead awesome to boot!"

As far as theater vs stereo system, I'm very much more concerned with 2 channel audio. I've kinda tacked-on the theater stuff as an "extra" for watching movies but my primary concern will always be having a great 2 channel system.

Thanks for all the advice, I'm a tinkerer at heart and a lot of the time I don't think things all the way through before I start cutting scrap wood to experiment with In the end, I guess I'd just like to use this space I have here to the maximum potential, as I can do pretty much whatever I want to it, no matter how terrible the WAF ends up being, even if it's something like... 4 ficar18s and 7x OBL-11s, even though I'd be saving up for a few years to build them all, lol.
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Old 12th July 2012, 01:28 PM   #22
Bigun is offline Bigun  Canada
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If you're looking for votes, I'd say keep going with the IB. Seems a shame however not to allow for use of low Fs drivers in the IB (if I understood correctly your in-wall drivers only go down to 70Hz Fs). I have found HT benefits from speakers with some 'punch' and deep bass because this is how a lot of movies have been mixed and if you can arrange that the front and surround speakers have good bass extension it works much better than a single large sub. I use large floorstanders for my HT system.

Then you can try something separate for your stereo, whether OB or a box speaker. I find stereo music benefits from having speakers that you can move around with some flexibility for positioning and even a pair of Frugal Horns may be what you end up with here instead of large OBs.
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Old 12th July 2012, 01:49 PM   #23
DrDyna is offline DrDyna  United States
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Originally Posted by Bigun View Post
If you're looking for votes, I'd say keep going with the IB. Seems a shame however not to allow for use of low Fs drivers in the IB (if I understood correctly your in-wall drivers only go down to 70Hz Fs).
I'd only ask them to go down that far, my HT receiver crosses over to my sub amp at 80 hz, and when I use the 2 channel rig, I have passive sub crossovers that are ~80 hz as well. If I put the mains in the wall they'd only have to go down that far.

I'm using a pair of Paul Carmody's ZX Spectrums as my mains right now, which I love, however I've been flirting with building new mains (aren't we all?) for quite a while, one of which is the Cryolite because I adore the Neo3 PDR. One of the ideas that floated across my mind was "Hey, maybe when I do the IB subs I could try to modify a mains design that would work well in IB."

I have a couple of my surrounds and center in the wall right now (you can see em in my video sorta), but there's never much musical information coming out of them so it's tough to gauge what to expect out of IB mains.
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Old 12th July 2012, 02:02 PM   #24
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Looks like you could build really big transmission lines in that space. Or, really big folded horns.
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Old 12th July 2012, 02:12 PM   #25
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Looks like you could build really big transmission lines in that space. Or, really big folded horns.
Interestingly, that's one of the things I considered, building something behind the wall that just vented forward. My T-TQWT subs almost ended up behind the wall with just the mouth section showing covered by a hvac register type vent.

This is all what got me thinking about IB, or OBL-11s while I was daydreaming about Cryolites. I was like...well, I've got the space...why not go big.
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Old 12th July 2012, 02:41 PM   #26
Paul W is offline Paul W  United States
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Having built several 2-channel OB systems, I really enjoy the way they can "light up" a room, provided I get the speakers 4-6' out from any walls.

Currently, the IB configuration provides me terrific clarity and articulation without diffraction/reflections from nearby surfaces.

If I were a 2-channel purist, I'd go OB. Otherwise, multichannel IB where you have adjustable room contribution.



PS: Definitely go with the 1/4 height and width subwoofers. Go easy with the surround level as it is easy to overdo...I am not inclined to ping-pong surround and use one of the matrix modes.
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Old 12th July 2012, 02:56 PM   #27
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Originally Posted by Paul W View Post
Having built several 2-channel OB systems, I really enjoy the way they can "light up" a room, provided I get the speakers 4-6' out from any walls.

Currently, the IB configuration provides me terrific clarity and articulation without diffraction/reflections from nearby surfaces.

If I were a 2-channel purist, I'd go OB. Otherwise, multichannel IB where you have adjustable room contribution.



PS: Definitely go with the 1/4 height and width subwoofers. Go easy with the surround level as it is easy to overdo...I am not inclined to ping-pong surround and use one of the matrix modes.
Wow, that room on your site is impressive, I only wish I could click the pictures for larger versions! I love your idea of crossovers on the side of the wall where you can get to them.

I'd love to do something like this, I just need to hit the lotto first, lmao.

I don't usually use any surround modes for music listening. The HTR is set so it comes out of however many speakers the track has. Even that I have plans to upgrade at some point to a unit that makes it easier to siamese my 2 channel rig into it, perhaps a pre-pro / multichannel amp combo. I've only got a couple of multichannel recordings, BT's This Binary Universe dvd (highly recommended) and Roger Waters.

I haven't read all of what you've written on your page yet, but it's very impressive indeed and it's giving me some cool ideas.
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Old 12th July 2012, 04:13 PM   #28
Bigun is offline Bigun  Canada
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What I've read is that with HT the sub is really just an LFE - 'low frequency effects' channel. It has been pointed out a fair bit on this forum that multiple subs are better than one large one for good l.f. response for music.

My experience in using large surounds and large front speakers is that you get low frequency response for everyone in the room so when you have a movie with explosions (don't all movies have them nowadays?) you get a much better sound field than just relying on a single sub.

When I used a single sub, placed at the front, even crossed over at 80Hz, I could still localize it to some extent. It sounds much better to my years to have large surrounds.

I found this out by accident. My original HT design had smaller box speakers for suround and a large sub because I thought on paper this should work well. I was given a pair of big floorstanders (for free) that I didn't have another use for so I put it into my HT system. It was a nice upgrade. Of course, some movies have poor surround sound, there's a large variation between movies.


p.s. paradoxically, I'm moving to mono for music
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Last edited by Bigun; 12th July 2012 at 04:19 PM.
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Old 12th July 2012, 04:22 PM   #29
DrDyna is offline DrDyna  United States
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Originally Posted by Bigun View Post
What I've read is that with HT the sub is really just an LFE - 'low frequency effects' channel. It has been pointed out a fair bit on this forum that multiple subs are better than one large one for good l.f. response for music.

My experience in using large surounds and large front speakers is that you get low frequency response from several places in the room and when you have a movie with explosions (don't all movies have them nowadays?) you get a much better sound field than just relying on a sub.

When I used a single sub, placed at the front, even crossed over at 80Hz, I could still localize it to some extent. It sounds much better to my years to have large surrounds.
The setting in my HTR for the lfe channel indicates that it's just routed to the subwoofer outputs, along with everything below 80 hz for every channel. I have 4 subs at the moment, 2 t-tqwts at the back and my old trusty corner loaders at the front. In the center of the room, bass just seems to "be a part of the room" which is how I like it.

Once the IB subs go in, they're going to be all that's driven from the subwoofer outputs. I'll move my corner loaders to the back with passive crossovers hooked up to R and L surround and the t-tqwts on the front L and R with passive crossovers as well, and set all the HTR controls for "large / no hpf".

Hopefully, all that will coincide with a new pre/pro and separate amplifiers.

Buuuut, I'm off on a tangent again. I guess at some point in the future if I can put something truly huge and impressive together like Paul W's Octagon, it'll probably be worth it, but with small drivers the mains are probably best kept boxed for now.
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Old 12th July 2012, 04:36 PM   #30
Bigun is offline Bigun  Canada
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With 4 subs you're all set !

It's a bit OT, but maybe the next step after the IB isn't more speaker building but room treatments.
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