Do tiny speakers with the same sensitivity really draw the same power as bigs?

[2Sunny]

I found this same question going as far back as 2003 so obviously nothing new here, and therefore my apologies if there is a recent thread on the same issue. The real issue is which speakers to hook up to an amp. Logically the tendency for me would be to place the towers and center on my amp, but in my case my towers are the most efficient with sensitivity ratings of 90 dB/2.831V/m whereas my heights have listed sensitivity of 87 dB/2.831v/m and the bookshelves are 86 dB sensitivity. I'm thinking it actually makes the most sense to put the system's least sensitive or hardest to drive speakers on the amp and leave the efficient towers on the AVR.

Does it make sense in my 5.2.4 system to put the center plus 2 bookshelves plus 2 heights on the amp and leave the towers and 2 heights on the AVR? Does it really matter?

Do those tiny heights really draw more power than the towers?

 

[Sokel]

I found this same question going as far back as 2003 so obviously nothing new here, and therefore my apologies if there is a recent thread on the same issue. The real issue is which speakers to hook up to an amp. Logically the tendency for me would be to place the towers and center on my amp, but in my case my towers are the most efficient with sensitivity ratings of 90 dB/2.831V/m whereas my heights have listed sensitivity of 87 dB/2.831v/m and the bookshelves are 86 dB sensitivity. I'm thinking it actually makes the most sense to put the system's least sensitive or hardest to drive speakers on the amp and leave the efficient towers on the AVR.

Does it make sense in my 5.2.4 system to put the center plus 2 bookshelves plus 2 heights on the amp and leave the towers and 2 heights on the AVR? Does it really matter?

Do those tiny heights really draw more power than the towers?

You should wonder what heights are playing, to what extend, range and level.

 

[2Sunny]

You should wonder what heights are playing, to what extend, range and level.

Exactly. I tried to find any information on what sounds heights are really emitting. In my experience so far it's been bullets, rain, babies passing through dimensional portals, and other low volume sounds so part of me thinks they very likely have a miniscule power draw so I SHOULDN'T put them on the amp, but I was thinking maybe someone out there has identified a movie scene that spiked heights and if so I'd love to hear about that.

 

[Sokel]

Exactly. I tried to find any information on what sounds heights are really emitting. In my experience so far it's been bullets, rain, babies passing through dimensional portals, and other low volume sounds so part of me thinks they very likely have a miniscule power draw so I SHOULDN'T put them on the amp, but I was thinking maybe someone out there has identified a movie scene that spiked heights and if so I'd love to hear about that.

I would narrow it down to bass/mid-bass effects.
As long as they don't play that anything else needs nothing in terms of power.

 

[Old_School_Brad]

babies passing through dimensional portals,

That's a strangely specific reference..

 

[JSmith]

That's a strangely specific reference..

Probably Doctor Strange... it's a multiverse of madness.


JSmith

 

[Clmrt]

Are the heights sent a full range signal?

 

[2Sunny]

That's a strangely specific reference..

2:41 in . . . one of my favorite Atmos testing scenes

 

[Old_School_Brad]

2:41 in . . . one of my favorite Atmos testing scenes

Great movie.

 

[Steve Dallas]

My surrounds and heights are mostly just low-level noisemakers from what I have heard from them. In my small home theater, they are probably using <1-3W continuously most of the time. For the occasional loud effects, the subs are doing most of the work, and 1 or 2 of the others are momentarily peaking at 10 to 20W most likely.

You can tell by looking at the gain settings for each speaker after running the setup routine. Even though I have a menagerie of different impedances among my speakers, they are all set within 4dB of each other by the software. Yes, it takes 2x power to increase SPL 3dB, but considering how little content those speakers play at such low SPL, it is all still well within the ability of the onboard amps.

Therefore, I run my front 3 on separate amps and just let the AVR handle the rest. I seriously doubt giving them any more power or headroom would make any audible difference at all.

Of course, room size, listening distance, listening level all factor in, so YMMV.

 

[2Sunny]

Very interesting related find. I tried to find the reference material, but no luck. I am willing to believe the info is correct because when queried as to the source of the information the poster had what sounded to be reliable intel.

I also downloaded the NIOSH app which shows dB at my MLP, and I discovered that for me anything registering over 85-90 dB and I'm not enjoying it . . . so . . . the implication is I REALLY do NOT need an amp. Funny enough mine is out for repairs at the moment so I watched a couple movies using just the Sony AVR and it sounds great. I'll probably keep the amp just to be sure, but I also think I'll try running without for a while.

Do some people actually listen to movies or music at 105 dB? I get that subs can put out some big numbers, but what kind of "normal" sounds could possible reach the plus 100 dB level. Certainly not music; at least not in a normal sized room or maybe if you're trying to hit "concert" levels of sound, but then I always brought ear plugs to every concert I ever attended - I know - what an old fuddy-duddy.

Maximum possible dynamic peaks in movie soundtracks are as follows:

LCR channels - 20dB = 105dB at reference
Bed surrounds - 17dB = 102dB at reference
Height channels - 14dB = 99dB at reference
LFE channel - 30dB = 115dB at reference

So all other things being equal, Atmos channels need 25% of the power of LCRs, surrounds need 50% of the power of LCRs, subwoofer(s) needs 10x power of LCRs.

That's interesting, though not something I've come across before: I'd aimed for 105db for all speakers (115db for the subs) when I designed my set up, though I tend to listen 10dB below anyway.

What is the source for those figures? (Not being argumentative, but I know someone who might be).

Three sources:

1. Anthony Grimani (ex-Dolby, ex-THX, CEDIA trainer and custom installer to the rich and famous) in various Youtube videos, one of which I linked you to the other day.

2. Brian Vessa (Director of Digital Audio Mastering at Sony Pictures) in a Youtube interview with Scott Wilkinson of AVS. He also explains that in many domestic mixes the 20dB LCR peaks are also pulled down to 17dB.

3. Dolby - in their Atmos mixing room specification guide. This is available to download online.

Using this SPL calculator: SPL Calculator

My system works out as only needing the following (taken the furthest distance where appropriate for a worst case calculation):

FWIW I had a 230 watts per channel power amp running 7 of the above channels, so you can see how completely OTT it was even for a reasonably large room (6.5 x 4 metres).

 

[userPaul]

Probably Doctor Strange... it's a multiverse of madness.


JSmith

some people just want control

 

[Steve Dallas]

Very interesting related find. I tried to find the reference material, but no luck. I am willing to believe the info is correct because when queried as to the source of the information the poster had what sounded to be reliable intel.

I also downloaded the NIOSH app which shows dB at my MLP, and I discovered that for me anything registering over 85-90 dB and I'm not enjoying it . . . so . . . the implication is I REALLY do NOT need an amp. Funny enough mine is out for repairs at the moment so I watched a couple movies using just the Sony AVR and it sounds great. I'll probably keep the amp just to be sure, but I also think I'll try running without for a while.

Do some people actually listen to movies or music at 105 dB? I get that subs can put out some big numbers, but what kind of "normal" sounds could possible reach the plus 100 dB level. Certainly not music; at least not in a normal sized room or maybe if you're trying to hit "concert" levels of sound, but then I always brought ear plugs to every concert I ever attended - I know - what an old fuddy-duddy.

That IS interesting, but about what I expected. My family is a mid-70dB kind of group, so I wasn't far off with the heights using < 3W most of the time and the surrounds using not much more. I guess we listen way below reference.

FWIW, the only reason I use an external amp on my LR is I can turn those amps off in the AVR and reduce heat and power supply stress, hopefully extending the life of the AVR. I also happen to own the amp, and its resale value is low. Should it ever die, I will just run the AVR's LR amps and move on. We way over-think this stuff.

 

[jcarys]

Your inclinations are right. If you are going to use an external amp, put it on the fronts and center where it's important. These three are putting out 80-90% of the total sound in a surround movie. (I'm assume it's a powered sub.) Your AVR can handle the surrounds and heights without breaking a sweat. The last time I borrowed an external amp to try at home, it was won of those "classic" designs with VU meters. I was rather dismayed to find out that when I was playing the stereo at ear bleed levels, the amp was sitting at 50 watts. Live and learn...

 

[kyuu]

I was rather dismayed to find out that when I was playing the stereo at ear bleed levels, the amp was sitting at 50 watts. Live and learn...

Even at ear bleed levels, I would be surprised to see an amp putting out an average of 50W. Unless you're outside or in a very large room listening from fairly far away. Or if the speakers are really inefficient.

 

[AnalogSteph]

When your amp says 50 W average on music, it may well be near or even beyond clipping unless it really is unusually powerful. Even material with a mere 6 dB crest factor (which is quite low) would mean it has to be good for 200 W peaks, and it's all up from there. By 12 dB we're talking 800 W, and we're not even at '80s CD dynamics yet. To say nothing about the speakers' opinion of all this.

VU meters also tend to be too slow to give an accurate representation of short peaks. Digital all the way.

 

[Chrispy]

Depends at what distances/levels as well as sensitivity differences in speakers. Post up specifics of the whole setup....

 

[Old_School_Brad]

Very interesting related find. I tried to find the reference material, but no luck. I am willing to believe the info is correct because when queried as to the source of the information the poster had what sounded to be reliable intel.

I also downloaded the NIOSH app which shows dB at my MLP, and I discovered that for me anything registering over 85-90 dB and I'm not enjoying it . . . so . . . the implication is I REALLY do NOT need an amp. Funny enough mine is out for repairs at the moment so I watched a couple movies using just the Sony AVR and it sounds great. I'll probably keep the amp just to be sure, but I also think I'll try running without for a while.

Do some people actually listen to movies or music at 105 dB? I get that subs can put out some big numbers, but what kind of "normal" sounds could possible reach the plus 100 dB level. Certainly not music; at least not in a normal sized room or maybe if you're trying to hit "concert" levels of sound, but then I always brought ear plugs to every concert I ever attended - I know - what an old fuddy-duddy.

Which value is it you refer to in the NIOSH app when you speak of dB? -That's really, really important.

 

[jcarys]

Even at ear bleed levels, I would be surprised to see an amp putting out an average of 50W. Unless you're outside or in a very large room listening from fairly far away. Or if the speakers are really inefficient.

50 watts were the peaks. And yes, AnalogSteph, VU meters were perfectly capable of showing dynamic output, particularly when they had a peak hold function. The amp I was using was rated at 200 watts to 4 ohms. My point was that the external amp was never working hard in my home setup, although I have always used efficient speakers.

 

[kyuu]

50 watts were the peaks.

Oh gotcha. Misunderstood, sorry about that. 50W peaks I can see.