how to account for room size when matching amp to speakers?

[dukehoops]

Hello,

I recently bought a pair of Focal Aria 948s and am researching matching integrated amps. I read up on the basics of speaker->amp matching and played with an SPL calculator. However, I can't find any advice on how to account for room size when sizing up an amp. ie assuming one fixes everything but room size:
* placement in the room: distance between speakers and between speakers and listening position,
* same speakers
* same listening level

how, if at all, would amp power requirements change as room size changes? I am assuming larger room --> more powerful amp needed? but by how much? is there a rule of thumb or a calculator?

thanks,

-nikita

 

[lovinthehd]

Why an integrated amp particularly?

Still depends on the spl desired and sure the boundaries will have an effect, but generally at your listening position you're mostly concerned with your distance from the speakers, but the sub(s) has more to do with the entire volume of the room.

Consider it takes a doubling of power to gain 3dB spl generally, so relatively small differences won't mean a lot in that respect....but if you want more amp get a lot more amp rather than try and only get a certain amount...and likely a pre amp/power amp gives you more power choices.

 

[AcuDefTechGuy]

Yeah, how LOUD do you listen and how FAR do you listen from?

 

[MalVeauX]

Hello,

I recently bought a pair of Focal Aria 948s and am researching matching integrated amps. I read up on the basics of speaker->amp matching and played with an SPL calculator. However, I can't find any advice on how to account for room size when sizing up an amp. ie assuming one fixes everything but room size:
* placement in the room: distance between speakers and between speakers and listening position,
* same speakers
* same listening level

how, if at all, would amp power requirements change as room size changes? I am assuming larger room --> more powerful amp needed? but by how much? is there a rule of thumb or a calculator?

thanks,

-nikita

Hi,

Room size really is just a relationship of the distance of your speaker(s) to the listening position(s). So to account for it in the calculator, you simply enter the distance of speaker to your listening position. That's the relationship. The more distance, the more power you'll need to maintain whatever target SPL you want at the listening position. Smaller rooms have less distance from speaker to listening position, so they're more efficient on power needs due to the proximity. Larger rooms tend to have more distance from speaker to listening position, but not always (you could have a huge room but sit 3 feet from the speakers for example, that's your choice).

Very best,

 

[Pogre]

Consider it takes a doubling of power to gain 3dB spl generally, so relatively small differences won't mean a lot in that respect....but if you want more amp get a lot more amp rather than try and only get a certain amount...and likely a pre amp/power amp gives you more power choices.

Yup. My rule of thumb is if you're adding amplification you should double what you have currently for any meaningful gain.

What are you wanting to know that the SPL calculator isn't telling you? Distance is what matters most with speakers. Room volume comes into play with subwoofers. Audioholics has a subwoofer/room volume formula of sorts.

Bassaholic Subwoofer Room Size Rating Protocol

This article outlines our test procedure in determining a subwoofers room size recommendation based on its max CEA SPL output while making room size and subwoofer distance assumptions.

www.audioholics.com

 

[Eppie]

Yup. My rule of thumb is if you're adding amplification you should double what you have currently for any meaningful gain.

What are you wanting to know that the SPL calculator isn't telling you? Distance is what matters most with speakers. Room volume comes into play with subwoofers. Audioholics has a subwoofer/room volume formula of sorts.

Bassaholic Subwoofer Room Size Rating Protocol

This article outlines our test procedure in determining a subwoofers room size recommendation based on its max CEA SPL output while making room size and subwoofer distance assumptions.

www.audioholics.com

Maybe a description of some SPL reference levels? Is that in the SPL Calculator FAQ? For a lot of people, I imagine that SPL levels are just a bunch numbers with little meaning. What are the SPL levels for a typical bar band, movie theatre or stadium concert? I've seen it posted in the forums but too lazy to look it up.

 

[Pogre]

Maybe a description of some SPL reference levels? Is that in the SPL Calculator FAQ? For a lot of people, I imagine that SPL levels are just a bunch numbers with little meaning. What are the SPL levels for a typical bar band, movie theatre or stadium concert? I've seen it posted in the forums but too lazy to look it up.

If you scroll down they have a list of examples and exposure time to compare with spl numbers.

 

[dukehoops]

howdy folks and thanks for all the responses. perhaps i phrased my original question poorly so I will try to rephrase: does room size alone affect amp power requirements? it sounds like the answer is "only for base / subwoofer frequencies" but let me make sure I am understanding correctly:

Example
Let's assume we have two rooms where speakers, positioning and target SPL at listening position are the same:
* target SPL of 85 db sustained / 105 db peak at listening position
* 2.0 setup with speakers: Focal Arias 948 x2. 8ohm nominal, 2.5ohm min; sensitivity: 92.5 dB SPL (1 W/1 M); recommended power range 50-320W
* distances: between speakers = 9ft; between either speaker and listening position = 14 ft

No suppose we have two rooms:
* A: 16ft x 20ft
* B: 24ft x 30ft (wall lengths 50% greater vs room A)

Will room B require a more powerful amp than room A to attain the above SPL? If so, how much more / is there a way for approximate?

For example, using Crown's amp power required calculator I get required amp power of:
* 314W with 20db headroom
* 198W with 18db headroom



...but, again, no mention whether a much larger room would drive up required power for the same target SPL?

 

[Pogre]

...but, again, no mention whether a much larger room would drive up required power for the same target SPL?

Distance is what matters most with speakers. Room volume comes into play with subwoofers.

What more are you asking?

 

[Pogre]

I mean, if you sit further from your speakers (distance) because the room is bigger (volume) then yes you'd factor it (the distance) to figure out your power needs for your speakers.

Room volume comes into play with subwoofer frequencies, not so much mid to upper frequencies for speakers.

 

[dukehoops]

Ahh missed the below initially. Ok, yes, answers my question. Thank you.

Distance is what matters most with speakers. Room volume comes into play with subwoofers.

 

[Pogre]

howdy folks and thanks for all the responses. perhaps i phrased my original question poorly so I will try to rephrase: does room size alone affect amp power requirements? it sounds like the answer is "only for base / subwoofer frequencies" but let me make sure I am understanding correctly:

Example
Let's assume we have two rooms where speakers, positioning and target SPL at listening position are the same:
* target SPL of 85 db sustained / 105 db peak at listening position
* 2.0 setup with speakers: Focal Arias 948 x2. 8ohm nominal, 2.5ohm min; sensitivity: 92.5 dB SPL (1 W/1 M); recommended power range 50-320W
* distances: between speakers = 9ft; between either speaker and listening position = 14 ft

No suppose we have two rooms:
* A: 16ft x 20ft
* B: 24ft x 30ft (wall lengths 50% greater vs room A)

Will room B require a more powerful amp than room A to attain the above SPL? If so, how much more / is there a way for approximate?

For example, using Crown's amp power required calculator I get required amp power of:
* 314W with 20db headroom
* 198W with 18db headroom
View attachment 47034


...but, again, no mention whether a much larger room would drive up required power for the same target SPL?

Heres an example. Your speakers' dispersion patterns are like flashlight beams, compared to a subwoofer which is like a naked light bulb. It doesn't matter as much how big the room is for speakers. It's the distance from the source of the "beam". A sub tries to "light up" the whole room.

 

[dukehoops]

Heres an example. Your speakers' dispersion patterns are like flashlight beams, compared to a subwoofer which is like a naked light bulb. It doesn't matter as much how big the room is for speakers. It's the distance from the source of the "beam". A sub tries to "light up" the whole room.

That’s a great analogy to help understanding!

 

[Pogre]

That’s a great analogy to help understanding!

Why thank you. I thought it was pretty clever myself.

 

[lovinthehd]

Some speakers have a more focused "beam" than others, too...but not particularly spl related.

If you want to consider boundary gain (if placed accordingly) this spl calculator may help out a bit, and the Crown calculator isn't accounting for two speakers.

howdy folks and thanks for all the responses. perhaps i phrased my original question poorly so I will try to rephrase: does room size alone affect amp power requirements? it sounds like the answer is "only for base / subwoofer frequencies" but let me make sure I am understanding correctly:

Example
Let's assume we have two rooms where speakers, positioning and target SPL at listening position are the same:
* target SPL of 85 db sustained / 105 db peak at listening position
* 2.0 setup with speakers: Focal Arias 948 x2. 8ohm nominal, 2.5ohm min; sensitivity: 92.5 dB SPL (1 W/1 M); recommended power range 50-320W
* distances: between speakers = 9ft; between either speaker and listening position = 14 ft

No suppose we have two rooms:
* A: 16ft x 20ft
* B: 24ft x 30ft (wall lengths 50% greater vs room A)

Will room B require a more powerful amp than room A to attain the above SPL? If so, how much more / is there a way for approximate?

For example, using Crown's amp power required calculator I get required amp power of:
* 314W with 20db headroom
* 198W with 18db headroom
View attachment 47034


...but, again, no mention whether a much larger room would drive up required power for the same target SPL?