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santiu
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Joined 2005
2023-03-23 9:50 pm
#1
- 2023-03-23 9:50 pm
- #1
hey all, in the never ending adventure to both have nice sound and WAF, i'd like to try to build a speaker for corner placement, which will mostly be behind a chair in the corner. This is for mono playback, so there's no second speaker, just one speaker in one corner. I'm currently listening to a linkwitz pluto, but although i like the sound the omni pattern and it works well with mono-playback, it really wants a closer listening position and i don't want to keep dragging the speaker out from the wall every time i want to listen.
The whole thing will use minidsp for crossovers/eq. Primary seating position is about 16 feet away from the corner (see attached poorly drawn room layout). Right now unless the Pluto is close (<9ft away or so), there's too many reflections going on in a bad way (expected but worse than i had envisioned).
so here's what i'm thinking to try to play well with the corner:
highs (>1250hz): B&C DE250-8 compression driver paired with either a HM17-25 or H6512 horn (horn and xover point to be decided upon testing/listening)
mids(300-1250hz): Dynavox LY302F 3.5" tucked right into the corner as close as i can get it
Lows (40-300hz): Dayton RSS210HO 8" woofer
see attached bad sketch of how i would arrange the drivers. view is at a 45deg section of the corner. I neither enjoy nor excel at woodworking, so i was hoping to just use the denovo knockdown cabinet for the 8" woofer. so all i'd have to build is a simple box to house the midrange. Unclear right now if i'd just mount the midrange box onto the wall, or have legs that go down to the woofer box.
I've seen Wayne's PI corner speakers and if i had the space i might just buy that. but they too big to pass the WAF test.
all thoughts, comments, criticisms, better ideas welcome! Thanks!!!!
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Lojzek
Member
Joined 2012
2023-03-23 10:53 pm
#2
- 2023-03-23 10:53 pm
- #2
No, this is wrong. You should be able to win by reassessing your strategy.
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santiu
Member
Joined 2005
2023-03-23 11:31 pm
#3
- 2023-03-23 11:31 pm
- #3
Lol, I should have been more explicit. The never ending adventure of experimenting with non-traditional speaker designs and convincing the family to let them live in the living room for long periods of time 😉.
Lately I’ve been on a kick of listening to old mono jazz LPs through a single mono speaker. Call me crazy, I think it’s a fun challenge to see how great I can make these 70 year old spinning plastic discs sound. Hence the mono speaker project. It’s all in good fun
I agree I could try to convince the other half to make/buy furniture speakers (although un-likely that I’d be able to displace the carefully selected credenza). But they tend to be very traditional designs which aren’t as much fun to me. The image you suggested looks like a basic bookshelf speaker that’s annoyingly close to the back wall (not close enough to ignore/work with, not far enough to be less of an issue). I feel like there might be other options in the solution space.
AllenB
diyAudio Moderator
Joined 2008
Paid Member
2023-03-24 2:55 am
#4
- 2023-03-24 2:55 am
- #4
It's difficult to ascertain your purpose or requirements. A typical corner speaker would, at higher frequencies, be trying to stay off the walls. Your choice of horns with their smaller 5"-6" dimensions is not going to do too much below a few kHz. In any case, a 3.5" is going to be so wide down there that it might just collaborate, but to what end?
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santiu
Member
Joined 2005
2023-03-24 4:22 am
#5
- 2023-03-24 4:22 am
- #5
Yeah that was the idea. Use some sort of waveguide until the 1/4 wavelength was greater than the distance that I could get the midrange to the walls. With a 3.5” midrange that would be about 2khz, so I figured if I used a waveguide to keep the high frequency reflections from the adjacent walls minimized, then below 2khz the midrange would be close enough the the boundaries that the first reflection from the corner could be ignored. Since at 2khz the 3.5” would be nearly Omni anyways then I was hoping to have a nice clean polar pattern from there downward with no reflections from the two adjacent walls. Does that make sense or am I being an idiot?
The goal was to have a single speaker fill the room as uniformly as possible while minimizing early reflections. It seems like those early reflections make a big difference as their amplitude is relatively high compared to the direct sounds since the source is so far away.
But then the 3.5” can’t play that low hence 3-way
In retrospect the HM17-25 isn’t a great choice. But the 12” wide H6512 seems like it might do the trick? I’d love to use a JBL 2384 but I think it would get kicked out of the room quickly
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santiu
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Joined 2005
2023-03-24 4:39 am
#6
- 2023-03-24 4:39 am
- #6
Oh, here’s the directivity plot from the Econowave mini s-8 which uses that smaller HM17-25 horn, and it’s being crossed at 2khz I believe. Seeing it still control horizontal dispersion to <90deg above 2khz is what led me to think it might work to minimize those initial reflections from the corner placement
https://techtalk.parts-express.com/filedata/fetch?id=1131975
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AllenB
diyAudio Moderator
Joined 2008
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2023-03-24 4:43 am
#7
- 2023-03-24 4:43 am
- #7
It's good to see you're asking the right questions.
It's not always possible to keep 1/4 wavelength but it's not always necessary. In a waveguide system you rarely have the luxury in the vertical or depth dimensions, and it's not a dealbreaker for a number of reasons. Waveguide performance is important.
santiu said:
below 2khz the midrange would be close enough the the boundaries that the first reflection from the corner could be ignored.
This particular compromise is one of the more significant when designing a corner speaker. It can be made a non-issue with much care and calculation, but at 2kHz I suspect it will still be a compromise. Not saying that you shouldn't continue, a compromise is a considered action and that's OK.
santiu said:
But the 12” wide H6512
The smaller dimension is the trouble spot. See here - https://www.diyaudio.com/community/threads/is-it-best-to-use-a-non-axisymmetric-waveguide.375799/
santiu said:
Seeing it still control horizontal dispersion to <90deg above 2khz
You may be right, I'm not sure. It's not normalised to power and it's blurry. Perhaps it's lower directivity is being controlled by diffraction and it's difficult to see that in the measurement.
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picowallspeaker
Member
Joined 2007
2023-03-24 6:00 am
#8
- 2023-03-24 6:00 am
- #8
Nice thread you opened, Allen!
I liked post #14, though I don't recall that guy (he knows Geddes...) to post that often..
So it's a very difficult matter...I'd avoid them, or Better, use the 90° angle corner as It Is, a horn.
Idea!! Excavate in the Wall !! Just a tiny hole to place a bare 1"dome.
Woofer would then Need to be delayed, I Guess...
The thing that 'sounds' unnatural to me it's the need to digitize the signal, since the source Is a turntable.
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santiu
Member
Joined 2005
2023-03-24 5:10 pm
#9
- 2023-03-24 5:10 pm
- #9
AllenB said:
This particular compromise is one of the more significant when designing a corner speaker. It can be made a non-issue with much care and calculation, but at 2kHz I suspect it will still be a compromise. Not saying that you shouldn't continue, a compromise is a considered action and that's OK.
The smaller dimension is the trouble spot. See here - https://www.diyaudio.com/community/threads/is-it-best-to-use-a-non-axisymmetric-waveguide.375799/
Do you think the XT1086 would be a better choice? any other ideas for horns for this application? the ME464 seems maybe a decent choice but that's really pushing the limit of WAF acceptable size (pretty sure if i painted the XT1086 white and made a nice natural maple shelf to support it that that would be acceptable).
Better, use the 90° angle corner as It Is, a horn.
Idea!! Excavate in the Wall !! Just a tiny hole to place a bare 1"dome.
i'm not opposed to this idea actually! my main concern is how to properly blend the hole to the walls (which then makes the "damage" to the walls much bigger should the idea not work out). also this would not have any vertical control compared to using a horn in the corner.
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AllenB
diyAudio Moderator
Joined 2008
Paid Member
2023-03-24 11:50 pm
#10
- 2023-03-24 11:50 pm
- #10
I'm of the thought that there is no commonly available horn that does what I want and I have to DIY it. There is a tendency for commercial horns to be designed for loading, or for small vertical spacing or small vertical angle, or intended for pro use where drivers are crossed high... but not for lower frequency waveguiding performance. Maybe the XT1086 is closer than some and may be a step forward in your journey, just make sure you understand it's limitations, find it's useful lower frequency and don't expect more than it is designed for.
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