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Re: Ideas on 31'L x 23'W room for fronts, 7.1 back
davekro #247434 02/17/09 06:47 PM
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 Originally Posted By: davekro
 Originally Posted By: dewd
Dave, Here is a neat calculator to show SPL from various watts/distances. Just plug in the specs from your amp, the speakers, and your room. According to some quick entries, you will be able to get over 100DB (way above reference) using the M60's with your AVR.

http://myhometheater.homestead.com/splcalculator.html

PS - Be sure to add to the watts entry and recalculate to see the effect....


Dewd,
Thanks for the calculator. I ran across it a few days ago and forgot to back and 'use it'. ;o)
That said, I do not understand what these terms translate too:
1) dB gain from amplifier?
(going from 90wpc to 130wpc only raises this from 19.5 to 21.1dB)

2) dB Loss due to dispersion (distance)?
(Using 12' dist. this remains constant at -11.3dB)

3) dB Gain from sonic reinforcement (multi speakers)?
(constant at 8.5dB)

I get your point on the Sound Pressure Level changing from 109.7db @ 90wpc to 111.3dB @ 130dB. I assume this means my 90 wpc amp has headroom above what I might listen to a loud action movie at.

In their calculator, all the above is based on avg 8ohm imped. The other power hang up ;o) I have had was that my 1909 could not handle the 4ohm M80's. The 1909's specs read:
6 - 16 ohms
90 wpc (8ohms, 20Hz-20kHz, with .08%THD)
120 wpc (6ohms, 1kHz with .7%THD)
I'm not sure but I think these specs say THD increases almost 9 fold when dropping to just 6ohms. I assume distortion increase would even much worse if the 1909 saw a 4ohm load, not to mention a 4 ohm load being detrimental to the 1909. Do I have this correct.
tks


I'm at work right now and do not have links to everything, but a quick search will yield 1000's of results.

Real quick basic knowledge.... It takes double the amount of power (watts) for each 3db increase. So if you get 100db with 90 watts, you will need 180 watts to get 103db. For reference, 3db is generally considered the first "noticeable" increment, with +10 db being perceived as double the volume.

So you can see that with your current AVR producing hearing loss levels at your primary seat, you would have double your power for just 3 db more (you will be deaf either way, so save your money for hearing aids). \:\)

Last edited by dewd; 02/17/09 06:48 PM.
Re: Ideas on 31'L x 23'W room for fronts, 7.1 back
dewd #247452 02/17/09 07:37 PM
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Now that is a convincing sales pitch for 5.1. "Get 5.1 or go deaf, your choice." I like it. Or, he could use the analog output from his recevier to power a Bryston or Krell 250/c external amp to drive the rear speakers to match the dB of the fronts at the seat - just don't get caught standing near the rear speakers when a helicopter flies over at 120db at the back wall/center of kitchen!
Seriously, if you really want 7.1 have you considered in-ceiling speakers at a distance much closer than 16'. There are some decent models with aiming tweeters to get the axis off of horizontal. The other benefit is the 7.1 music is still spread to your kitchen area without the WAF problems of putting big speakers in the back. Just a thought.

Last edited by Zimm; 02/17/09 07:38 PM.

Panny 3000 PJ, 118" Carada, Denon 3300, PS3, Axiom QS8, PSB 5T, B&W sub, levitating speaker wire
Re: Ideas on 31'L x 23'W room for fronts, 7.1 back
Zimm #247453 02/17/09 07:40 PM
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Or QS-8s ceiling mounted?


::::::: No disrespect to Axiom, but my favorite woofer is my yellow lab :::::::
Re: Ideas on 31'L x 23'W room for fronts, 7.1 back
MarkSJohnson #247458 02/17/09 07:53 PM
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 Originally Posted By: MarkSJohnson
Or QS-8s ceiling mounted?

My mental image of his room made that option unworkable. Now that I have formed that image, I can't agree with QS8s on the ceiling. Just ignore Mark, he is wrong.






\:D


Panny 3000 PJ, 118" Carada, Denon 3300, PS3, Axiom QS8, PSB 5T, B&W sub, levitating speaker wire
Re: Ideas on 31'L x 23'W room for fronts, 7.1 back
Zimm #247464 02/17/09 08:00 PM
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Statistically speaking, you're likely correct! \:\)


::::::: No disrespect to Axiom, but my favorite woofer is my yellow lab :::::::
Re: Ideas on 31'L x 23'W room for fronts, 7.1 back
MarkSJohnson #247472 02/17/09 08:08 PM
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\:D \:o \:\)


Panny 3000 PJ, 118" Carada, Denon 3300, PS3, Axiom QS8, PSB 5T, B&W sub, levitating speaker wire
Re: VP100's as 7.1 back speakers OK?
MarkSJohnson #247482 02/17/09 08:32 PM
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Mark,
I have already seen your, um, 'ported' rear. No need to repost! ;o) ANd as was mentioned before, PLEASE do not post your front (this is a family thread;o).

Watching Wall-E yesterday was great. It had a lot of extended 7.l tracks to be able to move around the room to see how well my current small bookshelves filled the rear space. Specs wise thes Bic V52's are very similar to the M2's, except V52's have a smaller twtr at 1/2" (vs. 1").
Audyssey on my Denon 1909 had set:
FL +6; FR +5.5; C +4.5; SW +3; SL +6; SR +6.5
SBL +4.5dB; SBR +6.0
The backs were weak at list. pos. at this setting.

To keep the same balance between L&R, I raised both by +6dB to max (for SBR):
SBL +10.5; SBR +12

As mentioned earlier, this felt like it 'almost, but not quite' enveloped the list. pos. from the rear.

In your opinion, (if I am not able to upgrade to your 'rears'), the upgrade to the following would be marginally better by?:
M2's?
M22's (on sides)?
VP100's (oem x-over at 2.7kHz)?
VP100's (∆ to M22's 3.5kHz x-over a no go per Brent at Axiom)*

*I heard back from Brent at Axiom.


Dave

"In theory, practice and theory are the same. In practice they're not."
Re: Ideas on 31'L x 23'W room for fronts, 7.1 back
dewd #247489 02/17/09 08:44 PM
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Thanks Dewd,
I'll Google those terms.

I'm sorry. Would you repeat that? I didn't hear you... ;\)


Dave

"In theory, practice and theory are the same. In practice they're not."
Re: Ideas on 31'L x 23'W room for fronts, 7.1 back
Zimm #247493 02/17/09 08:56 PM
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 Originally Posted By: Zimm

Seriously, if you really want 7.1 have you considered in-ceiling speakers at a distance much closer than 16'. There are some decent models with aiming tweeters to get the axis off of horizontal. The other benefit is the 7.1 music is still spread to your kitchen area without the WAF problems of putting big speakers in the back. Just a thought.


Zimm, in ceiling 7.1's never even crossed my mind. (amazing because it is a relatively short distance!) I like the idea of not trying to send the rear sound from so far back. Wow, this time I really do respect your position. (though my vision is is not quite back yet) ;\)

You are aware, I will now need to search for or start a whole new thread on what kind and the absolute MOST perfect location for ceiling mounted 7.1's. A ton more research. I'm tellin' my wife, heh... talk to Zimm, it's not my fault! (attaches back of hand to forehead with Velcro...already in place, as head tilts back slightly, eyebrows raise beseechingly)


Dave

"In theory, practice and theory are the same. In practice they're not."
Re: Ideas on 31'L x 23'W room for fronts, 7.1 back
Zimm #247505 02/17/09 09:42 PM
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 Originally Posted By: Zimm
 Originally Posted By: MarkSJohnson
Or QS-8s ceiling mounted?

My mental image of his room made that option unworkable. Now that I have formed that image, I can't agree with QS8s on the ceiling. Just ignore Mark, he is wrong.


Given his avatar, his dislike of protrusions may be lees than your and mine Zimm. (Mark, "not that there's anything wrong with that!") He, who didn't love Jimmy Durante! ;\)


Dave

"In theory, practice and theory are the same. In practice they're not."
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