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post #91 of 98 Old 08-19-2017, 08:13 AM
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Originally Posted by Mark Seaton View Post
Again, it comes back to a question of what would be subjectively beneficial vs just intellectually interesting. Again, you would want a room with some very significant acoustic control to the space before attempting such a thing.
What? DIRECTIONAL BASS in the 5+width plus 4 tops FEED positions: As indispensable as food, air, water, and hot babes (preferably full body tattooed) You will thank me, this is not some hypothesis this is 20% of the addictive factor here at the HIX Lab.

No treatments here bubba, nearfield works wonders. Near Field/medium field is good not only for multidirectional bass, but it tends to keep them buggering excess seats out of the room that prevent the upper half atmos imaging extravaganza that is 40 percent of the most addictive epicurean thing in the history of man. I did not know what I had here until Taker put it on video and I invited the owner of the firm representing the best 7 waterfront properties going up in Miami. I asked him, so does it feel like from 30 years in the future and he said yes, you have outdone yourself, bring the system into town and you will meet my patrons. Of course the kaleidescape helps. Kit without curated content is chinola.Having the only true great audio and hdr wcg source in the world is crucial where your 3 year old son can put together best atmos hdr scenes playlists ( wow i stole Atmos Rave Award last year from the big boys). Ya hear me Europa? When there is a will there is a way. Laziness is foolishness in this case.

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post #92 of 98 Old 08-19-2017, 09:36 AM
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Originally Posted by Mark Seaton View Post

The primary hurdle is attacking the room acoustics, subwoofer placement, and listener location to allow such groupings to still deliver desirable response to more than a few seats in 1 row. Once you accomplish that, then you have to evaluate if there is audible benefit and actual directional sensations. In my experience, the room acoustics and how the location of the bass source interacts with the acoustics can have as much or more effect on any subjective, directional perceptions at low frequencies than where the source actually is vs. the listener. Reducing strong modal interactions resulting in big peaks and nulls through the room greatly reduce the bizarre effects sometimes heard during a low frequency sine-sweep where the apparent source can appear to be swimming or rolling back and forth in the room.
Good point take your planned 20 seat theater and put two sofas behind one another, BE SELFISH, let the other leaches seat in bean bags. Fewer seats is your best friend.

You do not sacrifice directional bass for anyone one, kin or not. Can you keep bass directionality in an 8 seater, it's time to ditch any consideration past 8 seats which is stretching the recommended max 6 seater layout, for atmos envelopment around your head and now I cannot overemphasize DIRECTIONAL BASS for the trough the torso Gravity Premiere selfish bastard seminal event..
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post #93 of 98 Old 08-19-2017, 10:47 AM
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Originally Posted by Mark Seaton View Post
I do believe what you describe could be made to work, albeit a little trickier to insure the blend and balance of the VLF sub vs the zoned arrays. You would have to assign a high pass to all of the zoned subs at say 40Hz, and then low pass the VLF subs at 40Hz. You would then want to route the bass of each speaker to both the selected zones and the VLF subs to cover the full bass range. You would then ideally also want to feed the .1 LFE channel to all of the zoned subs along with the VLF subs.
Mark your brain is uniquely capable to switch lobes, unlike most of our dearest engineer friends. Just shut off everything below whatever the venue threshold is 40, 34, 48. Whatever just determine the lowest note that conveys direction in that space for no more than three rows of three. In marks case a sofa, so perfect. Then fire up the low sub channel, bring crossover up at the point you start losing directionality, dial back a notch then work on the balancing and level etc of the lower sub channel. You may lose some of the famous seaton signature sound where your subs cover monochannely up to higher frequencies but I trust you can take this to recreate the through the torso from every angle highly addictive experience from the gravity premiere and now the HIX.

Are you up to the task at Marks? We are not mice our kin.
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post #94 of 98 Old 08-19-2017, 11:22 AM
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Originally Posted by maikeldepotter View Post
Yes, but with a sensitivity of only 86 dB it is doubtful if it can handle the 300W you need to reach reference level (105 dB) at 2 meters distance.
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Do you mean that the Gem2 will be required to handle 300W continuous, 600W peak or?

How did you arrive at the 300W value?

Will the Gem2 be excursion or power dissipation limited?
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Originally Posted by maikeldepotter View Post
Doubling the distance requires adding 6 dB, and every 3 dB increase requires doubling the power. So to get from 86 dB at 1 m (1 W) to 105 dB continuous at 2 meter you need (19+6)/3= a little over 8 of those doublings. This gets you to about 300 W. The 3 dB head room on top of that may be covered by boundary gain as this is a wall-mounted speaker. So 150 W continuous and 300 W peak should do it.

This calculator can be helpful: http://myhometheater.homestead.com/splcalculator.html

I don't know, but what surprised me was not being able to find any specification on the power handling of this speaker.

SPL typically drops off at 3 to 4 dB per doubling of distance in a room. 6 dB is more appropriate for a 4 pi space without boundaries.


Your calculations are for required amplifier power, and don't relate directly to how much power the Gem2 can handle. The crest factor of movies or music mean that a speaker won't be handling even close to the full power of the amplifier for any significant amount of time. Your original claim was that the Gem2 couldn't handle the power to meet the requirements of home theater, but after bad mouthing the speaker, you haven't offered support for that position.


Looking at the calculator, the 1st line of text on the calculator website is:

"This calculator will compute the predicted maximum sound pressure level (loudness) at the listening position."

This isn't a promising start since SPL and loudness are two very different things. SPL is a repeatable measurement. Loudness is related, but is based on human perception.

SPL: https://en.wikipedia.org/wiki/Sound_...pressure_level
Loudness: https://en.wikipedia.org/wiki/Loudness

pressing on...

Here is a description from the site of how distance is calculated:

"3. The distance from the speaker to the listening position. Expressed in feet. If you know the distance in meters, divide by 3 to get an approximation in feet."

A meter is longer then a foot, about 3.3 times longer. Dividing meters by a number greater than one is not a good start. It's an elementary school mistake. Here is a length converter that appears to be accurate for future use:

http://www.rapidtables.com/convert/l...er-to-feet.htm

The author of the site clearly doesn't understand basic distance measurements or sound level measurements. It's hard to give credibility to the remainder of the site given these errors.
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post #95 of 98 Old 08-19-2017, 03:38 PM
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Originally Posted by bigguyca View Post
SPL typically drops off at 3 to 4 dB per doubling of distance in a room. 6 dB is more appropriate for a 4 pi space without boundaries.
True.

Quote:
Your calculations are for required amplifier power, and don't relate directly to how much power the Gem2 can handle.
I don't know how much it can handle. Do you?

Quote:
Your original claim was that the Gem2 couldn't handle the power to meet the requirements of home theater
I merely expressed my doubt on its power handling, as I could not find it specified on manufacturers web site nor anywhere else.

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but after bad mouthing the speaker,
I missed that, where did I do that?

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you haven't offered support for that position.
What position? That I have doubts about a specification that is not published?

What would your suggestion be for the required continuous/peak power handling of a speaker with this sensitivity, given this room and reference level requirement?

A good idea and understanding lies at the basis of every successful project.
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post #96 of 98 Old 08-20-2017, 12:49 AM
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Quote:
Originally Posted by Mark Seaton View Post
I do believe what you describe could be made to work, albeit a little trickier to insure the blend and balance of the VLF sub vs the zoned arrays. You would have to assign a high pass to all of the zoned subs at say 40Hz, and then low pass the VLF subs at 40Hz. You would then want to route the bass of each speaker to both the selected zones and the VLF subs to cover the full bass range. You would then ideally also want to feed the .1 LFE channel to all of the zoned subs along with the VLF subs. I believe this is possible, but I haven't tried the exact config. Of course you will quickly use up channels with a minimum of 4 required to experiment with it, where you might want as many as 10 outputs to play with.

Again, it comes back to a question of what would be subjectively beneficial vs just intellectually interesting. Again, you would want a room with some very significant acoustic control to the space before attempting such a thing.

Quote:
Originally Posted by CINERAMAX View Post
Mark your brain is uniquely capable to switch lobes, unlike most of our dearest engineer friends. Just shut off everything below whatever the venue threshold is 40, 34, 48. Whatever just determine the lowest note that conveys direction in that space for no more than three rows of three. In marks case a sofa, so perfect. Then fire up the low sub channel, bring crossover up at the point you start losing directionality, dial back a notch then work on the balancing and level etc of the lower sub channel. You may lose some of the famous seaton signature sound where your subs cover monochannely up to higher frequencies but I trust you can take this to recreate the through the torso from every angle highly addictive experience from the gravity premiere and now the HIX.

Are you up to the task at Marks? We are not mice our kin.
Without significant acoustic bass control, you could also take the "design follows function" route to the extreme, and find a way to position the VLF subs diagonally at the intersection of the 2nd order width and 2nd order length modes (eliminating all 1st and 2nd order lenght and width modes in the room), and distribute the remaining zoned subs as shown below (green arrows showing the bass management routing, dotted green arrows showing some additional/recommended? options for dual or triple subs per channel, blue arrows showing the 'average' direction of attack towards MLP). Then follow Peter's suggested approach for determining the optimal crossover point between the VLF and zoned subs, and Mark's suggestion to feed the LFE channel to both VLF subs and ALL of the zoned subs. All main speakers (including LCR) can now be identical and 'small' (e.g crossing over at 100-120 Hz).

Who's going to take the plunge first?
Thomas, are you still with us? Save your coins on those big LCRs and put them in subs!

PS Relocated wides and side surrounds to IMO more optimal positions ...

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Last edited by maikeldepotter; 08-21-2017 at 01:32 AM.
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post #97 of 98 Old 08-20-2017, 09:17 AM - Thread Starter
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Originally Posted by maikeldepotter View Post
Thomas, are you still with us? Save your coins on those big LCRs and put them in subs!
I'm still there, but I'm missing the time to respond.

I'll come back here and publish a bunch of posts as soon as I have the time!

Greetings!
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post #98 of 98 Old 08-21-2017, 03:39 AM
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Originally Posted by bigguyca View Post
Looking at the calculator
Yes, I only referred to the calculator (as in: can be helpful), not to the site, let alone the author.

Apart from the fact that the reverberant sound field (of a sinus wave or pink noise) causes the SPL to decrease with less than 6 db per doubling the distance, there is nothing inherently wrong with the math behind this calculator. It still can give good ballpark ('safe side') figures for those concerned with the ability of a speaker to deliver (maximal continuous) reference level at the listening position.

As for the estimation of 150/300 W power requirement:
- the room diagram shows distances up to 3 meter from surround speaker to listener instead of the 2 meter I used
- I applied 3 dB wall gain which is probably exaggerated for a bass managed surround speaker

So again: If you assume the reverberant sound field to be as strong as the direct sound at 1 m distance from the speaker, you need about 37.5 W amplifier power to get from 89.4 dB (=86.4+86.4) to 105 dB at 1 meter. If tripling the distance gives not 10 db but let's say 6 dB SPL decrease because of this same reverberant sound field, you will still need a total of 150 W amplifier power, with 3 dB headroom gives 300 W. Same result.

PS It should be noted that full reinforcement of the direct sound by the reverberant sound field takes a short period of time (like 100 ms or so). A lot of sounds contain dynamic peaks that fall within that time frame (e.g. gun shot, piano, 'attack' on a electric guitar, etc), which can have a great impact on the sense of realism. It is therefore mostly the direct sound from the speaker that can produce such dynamics, and in that sense the minus 6 dB per doubling the distance might still be a good measure.

If this speaker we were talking about can truly handle 150-300 W of amplifier power and produce at least 108-111 dB at 1 m (anechoic) without risking damage to its dome tweeter and/or exhibit serieus power compression/ audible distortion, I don't understand why the manufacturer does not specify it. That is why I expressed my doubts. Now if you know more than what I can google, please enlighten us with that information. And rest assured, I will not accuse you of bad mouthing this speaker if you can't find those specs either...

A good idea and understanding lies at the basis of every successful project.

Last edited by maikeldepotter; 08-24-2017 at 11:20 PM.
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