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Quote:
Originally Posted by localnet /forum/post/17954501


Here is what I use for my XPA-2 and 3...

http://www.audioadvisor.com/prodinfo...II%20%20BLKSIL

http://www.audioadvisor.com/prodinfo...II%20%20BLKBLK


They work and look pretty good. And the above was about the cheapest I found in this model.



Lowes has something similar but only costs $20 total (in my case), made of wood and can hold the XPA-5. You can get the wood in Black, blonde and stained. The legs are either silver or black and come in 4" 8" and 16" IIRC.


It's modular so you can build on to it shelf by shelf. It looks really good too.


I got the idea from someone's post in the Home Theater Construction forum.


Here are pics of a full shelf (stock photo).





I only have the bottom shelf at the moment.


 

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Hi, I am going to purchasing my first Emotiva amp (actually my first amp ever) in the near future. I have a rather novice question; I read here on AVS people often describing certain speakers as either "efficient" or "not the most/not very effecient", etc. I understand what there are referring to, however how would one determine what catagory their speakers would fall into?


I would speculate that my speakers, Boston VR970s (front L/R), would fall into the efficient catagory. Can any speaker gurus confirm this?


BTW, the amp I have decided on is an XPA-3 for the Boston VR970s and VR910 center, then let my Yamaha RX-V665 power the 4 Boston DSi-450 in-wall surrounds. Does this set-up make the most sense?


Advice, comments, etc. most welcome. Thx!
 

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Quote:
Originally Posted by KSE /forum/post/17959779


I read here on AVS people often describing certain speakers as either "efficient" or "not the most/not very effecient", etc. I understand what there are referring to, however how would one determine what catagory their speakers would fall into?

Your manufacturer should publish the efficiency in dB in the speaker's specifications.
 

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Quote:
Originally Posted by KSE /forum/post/17959779


Hi, I am going to purchasing my first Emotiva amp (actually my first amp ever) in the near future. I have a rather novice question; I read here on AVS people often describing certain speakers as either "efficient" or "not the most/not very effecient", etc. I understand what there are referring to, however how would one determine what catagory their speakers would fall into?


I would speculate that my speakers, Boston VR970s (front L/R), would fall into the efficient catagory. Can any speaker gurus confirm this?


BTW, the amp I have decided on is an XPA-3 for the Boston VR970s and VR910 center, then let my Yamaha RX-V665 power the 4 Boston DSi-450 in-wall surrounds. Does this set-up make the most sense?


Advice, comments, etc. most welcome. Thx!

Speakers specs are reported usually with a "sensitivity" such as 87dB or 93dB, which really means the sound pressure level at a distance of 1 meter with 1 Watt of power input.


So what does that mean? Well, keep in mind that you have to double the power input to the speaker to get an additional 3dB of sound pressure.


So, for example, if my speakers have a sensitivity of 92dB and yours have a sensitivity of 86dB, how much more power would you need for your speakers to get the same level of sound as mine?


If you double the power to your speakers, you get an additional 3dB, bringing yours to 89dB.


If you double the power again (for a total of four times the power) you get an additional 3dB, bringing yours to 92dB.


So in this example, you would need four times the power as I would to get the same level of sound output. So if you liked the volume of my system at 100 watt per channel, you would need 400 watt per channel for yours.


Sorry for the long explanation, but it will help you somewhat.


Speakers with sensitivities above 90dB are considered efficient. You need to find out the sensitivity specs for your speakers.
 

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pmd918, wow thank you. That was an excellent explanation. I just looked up their sensitivity, 91db.
 

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I too have been waiting for a good / great explanation on what makes an efficient speaker...PMD918 - Thank you!
 

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I think it's a 6 dB loss per doubling of distance. Not 20 dB.
 

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Quote:
Originally Posted by MichaelJHuman /forum/post/17961718


I think it's a 6 dB loss per doubling of distance. Not 20 dB.

Judging by the number of your posts, I'm going to assume that you are right. But that's not what I was taught.


Sound pressure drops with distance squared, so double the distance and that's 1/4 the sound. And 1/2 the sound is 10dB, so that would mean 20dB total.


But I admit I never tried it with an SPL meter
 

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Quote:
Originally Posted by MichaelJHuman /forum/post/17961718


I think it's a 6 dB loss per doubling of distance. Not 20 dB.

It should be 6dB. Radiated power drops as the square of the distance for just about everything, so doubling the distance gives you a quarter of the effective power.
 

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Quote:
Originally Posted by pmd918 /forum/post/17961754


Judging by the number of your posts, I'm going to assume that you are right. But that's not what I was taught.


Sound pressure drops with distance squared, so double the distance and that's 1/4 the sound. And 1/2 the sound is 10dB, so that would mean 20dB total.


But I admit I never tried it with an SPL meter

Half of the sound energy is 3db. Half of the human perceived sound volume is 10db.
 

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Quote:
Originally Posted by RoboRay /forum/post/17961763


It should be 6dB. Radiated power drops as the square of the distance for just about everything, so doubling the distance gives you a quarter of the effective power.

You guys are right - i don't know what I was thinking. Deleted the post, and will come up with better example when I'm not half asleep!
 

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Quote:
Originally Posted by RoboRay /forum/post/17961763


It should be 6dB. Radiated power drops as the square of the distance for just about everything, so doubling the distance gives you a quarter of the effective power.

Yes, but a normal listening room will retain a lot of energy which you will be hearing, so the perceived loss is not as high as it would be if you were listening outside in the middle of the desert for example.
 

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Quote:
Originally Posted by Pultzar /forum/post/17961784


Half of the sound energy is 3db. Half of the human perceived sound volume is 10db.

I'll have to take your word for that. I'm an electronics guy, not a physiology one.
 

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Quote:
Originally Posted by Pultzar /forum/post/17961784


Half of the sound energy is 3db. Half of the human perceived sound volume is 10db.

That's where I was taught wrong - I was told by more than one person that half the sound volume is 10dB.


Thanks for the correction - now I'll climb back into my hole
 

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10 dB SPL IS a perceived difference of twice (or half) the volume.
 

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Quote:
Originally Posted by pmd918 /forum/post/17959936


Speakers specs are reported usually with a "sensitivity" such as 87dB or 93dB, which really means the sound pressure level at a distance of 1 meter with 1 Watt of power input.


So what does that mean? Well, keep in mind that you have to double the power input to the speaker to get an additional 3dB of sound pressure.


So, for example, if my speakers have a sensitivity of 92dB and yours have a sensitivity of 86dB, how much more power would you need for your speakers to get the same level of sound as mine?


If you double the power to your speakers, you get an additional 3dB, bringing yours to 89dB.


If you double the power again (for a total of four times the power) you get an additional 3dB, bringing yours to 92dB.


So in this example, you would need four times the power as I would to get the same level of sound output. So if you liked the volume of my system at 100 watt per channel, you would need 400 watt per channel for yours.


Sorry for the long explanation, but it will help you somewhat.


Speakers with sensitivities above 90dB are considered efficient. You need to find out the sensitivity specs for your speakers.
Quote:
Originally Posted by pmd918 /forum/post/17961451


No problem. This stuff can get confusing when you get into the math.


Here's lesson #2:


In order for the sound level perceived by your ears to double, you have to increase the sound pressure level by 10dB.


And as you move away from your speakers, every time the distance doubles the sound pressure level drops 20dB. So consider this example.


Your speakers have a sensitivity of 91dB (at 1 meter and 1 watt). And let's say that you want to listen to your system at the reference level of 75dB at 12 feet away (approx 4 meters).


So at 1 watt at 1 meter (~3 ft) the sound level is 91dB. Double the distance to 6 feet and it drops to 71dB, double it again to your listening distance of 12 feet and it drops to 51 dB.


You want 75 dB at that listening distance, so you need to boost the sound level 24dB (75dB - 51dB). How much power do you need?


Well, for every 3dB louder, you need to double the power. You need to double the power eight times (24dB needed divided by 3dB). So you would need:


1 watt x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 = 256 watts


Now this isn't exact because there are multiple speakers, but you get the idea. You should also start to get the idea why the difference between an amp with 75 watts per channel and 100 watt per channel is virtually meaningless.


A bit off topic for this thread, but it should give folks an idea of how amp power impacts volume.


Edit: Just wanted to add - now suppose you had inefficient speakers at 85dB sensitivity instead of 91dB. You would need another 6dB to reach your reference level, which means doubling the power two more times to 1,024 watts! Now do you understand how important speaker sensitivity and amp power are, and how they relate?

Thank You for the 411.... pmd918


Printed out both posts for my notes to fall back on.... I have an entry level AVR Denon 2307CI and am looking into using the pre-outs to upgrade the amps looking for cleaner more power, lower distortion. The 2307CI, is listed as .08%THD. My speakers are Definitive Technology: (Fronts) BP2000TL rated 91db, (Center) C/L/R 3000 rated 91db, (Side Surrounds) BPVX rated 90db and (Rear Surrounds) BP2X rated 90db.


Been reading up and down this thread on EMOTIVA Brand... Love the warranty on them and the input from all the posters have been great. I have my eyes on the XPA-1 for the fronts,center and side surrounds and an XPA-2 for my rear surrounds. I thought about using the XPA-2 for the fronts and the XPA-5 for the center and surrounds but every post here talking about the XPA-1 just makes me have a
...


Steve
 

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Quote:
Originally Posted by Steve Carr /forum/post/17961957


Thank You for the 411.... pmd918


Printed out both posts for my notes to fall back on.... I have an entry level AVR Denon 2307CI and am looking into using the pre-outs to upgrade the amps looking for cleaner more power, lower distortion. The 2307CI, is listed as .08%THD. My speakers are Definitive Technology: (Fronts) BP2000TL rated 91db, (Center) C/L/R 3000 rated 91db, (Side Surrounds) BPVX rated 90db and (Rear Surrounds) BP2X rated 90db.


Been reading up and down this thread on EMOTIVA Brand... Love the warranty on them and the input from all the posters have been great. I have my eyes on the XPA-1 for the fronts,center and side surrounds and an XPA-2 for my rear surrounds. I thought about using the XPA-2 for the fronts and the XPA-5 for the center and surrounds but every post here talking about the XPA-1 just makes me have a
...


Steve

Read the last few posts - my second example was wrong.


But it still illustrates the impact of speaker efficiency.
 

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Quote:
Originally Posted by pmd918 /forum/post/17962018


Read the last few posts - my second example was wrong.


But it still illustrates the impact of speaker efficiency.

I try not to get that technical with HT. Don't need to know how the transmission works... just need to know how to work the transmission...



Steve
 

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Quote:
Originally Posted by Steve Carr /forum/post/17961957


Thank You for the 411.... pmd918


Printed out both posts for my notes to fall back on.... I have an entry level AVR Denon 2307CI and am looking into using the pre-outs to upgrade the amps looking for cleaner more power, lower distortion. The 2307CI, is listed as .08%THD. My speakers are Definitive Technology: (Fronts) BP2000TL rated 91db, (Center) C/L/R 3000 rated 91db, (Side Surrounds) BPVX rated 90db and (Rear Surrounds) BP2X rated 90db.


Been reading up and down this thread on EMOTIVA Brand... Love the warranty on them and the input from all the posters have been great. I have my eyes on the XPA-1 for the fronts,center and side surrounds and an XPA-2 for my rear surrounds. I thought about using the XPA-2 for the fronts and the XPA-5 for the center and surrounds but every post here talking about the XPA-1 just makes me have a
...


Steve

I own and love Emotiva amps....but I think most here will agree than XPA-1's for the surrounds would be overkill. Better that money be put into another component.....


Then again if you want to make the ultimate statement you should wait for Emotiva's 400 watt 7 channel XPR-7 amp due to be released sometime this year.
 
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