GM-416-8B MLTL Corner Cabinet

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Originally Posted by VolvoHeretic

Ok, how about this. :)

Attachment 3199

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Hi VolvoHeretic,

This is exactly comes to the measurement, thank you so much for the drawing.

-Sri

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Originally Posted by GM

Glad you mentioned this........ This project has had many 'blind alleys', discussing other's builds, etc., over several months and combined with me juggling more 'balls' than my mostly MIA memory can cope with, clean forgot about his room details, so when he said he wanted something similar to Billfort's '45' corner cab, away I went.


Now looking back at my notes, this is what I'd initially planned back at the beginning because with a floorplan with multiples of 2, it's not much better than a square one, so ideally want to stay in its near-field, so to speak.


This meant a ~10-12 ft listening distance [LP] from the sound wall, so when he said it was fixed at 17-20 ft, I scrapped it in favor of a 40" wide MLTL to allow the option of dual woofers and when that didn't pass the WAF test, but Billfort's would, I 'campaigned' again for the 40" as not being all that 'room dominating' in a corner.


At 45 deg, the speakers would be over-toe'd about perfect at ~10 ft, so obviously not at the ~20 ft next acceptable point, so that means what? 22.5 deg included?


This makes a much bigger cab, so would need to be truncated more to both shrink it and allow same/more positioning flexibility.


GM

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GM,

Sorry for the initial confusion and referring to many materials to educate myself. Thanks for the additional details. Sounds like this changes the current calculation/dims. If it helps, I will work on moving the listening position. Currently, the furniture is fixed (with its attachments) at ~17 ft from the corner speaker position. If it can eliminate some constraints, I can work on moving this to 12-14ft distance. Please suggest.


Thank you,
Sri

Here is the 15'x30' floor plan with the 45 and 30/60 speakers showing the preferred listening positions. Both speakers are the same area. I will later show a 22.5/67.5 degree.

If the horn is placed in its own enclosure, it could be pivoted separately for finer adjustment.

Attachment 3202

Quote:

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Originally Posted by VolvoHeretic

Here is the 15'x30' floor plan with the 45 and 30/60 speakers showing the preferred listening positions. Both speakers are the same area. I will later show a 22.5/67.5 degree.

If the horn is placed in its own enclosure, it could be pivoted separately for finer adjustment.

Attachment 3202

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VolvoHeretic,
Thanks for the drawing, this is really helps to see the arrangement visually.

-Sri

FWIW, better to measure off the room as a function of odd harmonics, 3rds, 5ths, 7ths is enough with 1st of course being at the end wall.

Also, this has gone far enough that we ideally need a lot more details about the room as doorways, furniture, wall hangings, etc., come into play, so would like to see some pics and basic dimensioned floor plan if not too much hassle.

GM

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Originally Posted by srivenkat

Sorry for the initial confusion

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You're welcome!


No biggie, it's pretty rare for a pm/thread related to audio in general and speaker design in particular, to be narrow focussed and why so many leave in frustration once it becomes obvious that it's no trivial pursuit to do it at least reasonably right.


In retrospect, I should have requested you make several threads and it would be nice to at least do one for the A5 and follow it through as they're a perennial favorite here, especially WRT XO choices.


Well, sitting up relatively close to a horn speaker isn't my first choice, though what co/tri-axes are designed for, especially when the LP is < speaker spread, which might leave a 'hole in the middle' of some recordings even with over-toe'd speakers, i.e. normally means aiming the left speaker at the far right LP and vice versa.


The main thing is that they cross in front of the 'sweet spot' with the gap being a personal choice, though by and large, ~1.5 ft seems to work well.


Anyway, at this point and all things considered [so far :rolleyes2:], the ~20 ft/3rd harmonic mark is it.


edit:

All things considered, are you up for making half round speakers? Then they would fit at any angle plus would disperse any near wall reflections.


GM

Not sure I know what I'm drawing or why. :)
Srivenkat's Corner Speaker-Floor Plan-2

Attachment 3204

Quote:

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Originally Posted by GM

FWIW, better to measure off the room as a function of odd harmonics, 3rds, 5ths, 7ths is enough with 1st of course being at the end wall.

Also, this has gone far enough that we ideally need a lot more details about the room as doorways, furniture, wall hangings, etc., come into play, so would like to see some pics and basic dimensioned floor plan if not too much hassle.

GM

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GM,


In retrospect, I should have requested you make several threads and it would be nice to at least do one for the A5 and follow it through as they're a perennial favorite here, especially WRT XO choices.

Well, sitting up relatively close to a horn speaker isn't my first choice, though what co/tri-axes are designed for, especially when the LP is < speaker spread, which might leave a 'hole in the middle' of some recordings even with over-toe'd speakers, i.e. normally means aiming the left speaker at the far right LP and vice versa.


The main thing is that they cross in front of the 'sweet spot' with the gap being a personal choice, though by and large, ~1.5 ft seems to work well.

Anyway, at this point and all things considered [so far :rolleyes2:], the ~20 ft/3rd harmonic mark is it.


GM

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Thanks a lot, I sent you an email with room layout also couple of pictures. As, I just started setting this room there are no wall hangings and I was thinking of using sound treatment material depending on the need. Once I get my status to add pictures here, I will add the room measurement diagram.

Sure, I will start a thread on A5/A7 shortly and share my experience WRT XO.

I am with you in terms of sitting close to any speaker, I always prefer to stay little away from the sweet spot. So, its perfectly fine with your suggested distance or even more from sweet spot.

Thank you,
Sri

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Originally Posted by VolvoHeretic

Not sure I know what I'm drawing or why. :)
Srivenkat's Corner Speaker-Floor Plan-2

Attachment 3204

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VolvoHeretic, This pictures looks more detailed, couple of basic questions - how did you define the 'harmonic' lines and its distance? Any standard way to define these?

Thank you for the diagram.

-Sri

Srivenkat, I sure could be wrong, but if I understand harmonics correctly, the first harmonic is the total distance of the wall, 2nd is dividing the room in half, 3rd is dividing the room in thirds, 4th is dividing in fourths... I think that at these locations the sound waves are getting canceled out and you don't want to sit there. I was going to hang tennis balls at these spots, at forehead height, embedded with razor blades. :) I would like to know how wide these nulls are, 6", 4", 1"?

Thanks! We only want room mode peaks, so only odd harmonics shown please. The speakers will be ~at the sound wall [fundamental/1st harmonic], so ideally we want to listen from a peak, or at least that's going to give us the best overall room response of the lower half of the power spectrum in the horizontal plane.

GM

Ok.
Attachment 3205

Thanks, and a quick sketch with a protector [sic] says I guessed right at 22.5 deg/20 ft..

GM

edit: make that 'protractor'