front vs center channel speaker sensitivity

[mwhit]

How close do the sensitivity ratings need to be for the front vs. center channel speaker? I am considering using a 89db sensitivity rated speaker for the center channel, that would be matched up (same brand, similar drivers, etc) with 92db sensitivity rated fronts? Thanks.

 

[mwhit]

Please help....does anyone have any thoughts on this? Thanks.

 

[markw]

They should be pretty close, but if they are from the same manufacturer, same line, you should be fine. That's why receivers allow you to make adjustments to these levels. ...to keep the levels close.

 

[GranteedEV]

The important thing is a center that's tonally matched (same crossover frequency and drivers) and ideally you want it to be the exact same speaker, but...

As long as it has Auto-calibration, your surround receiver or prepro will set channel trims based on the distance and sensitivity.

So if your center is 3db too quiet at 12 ft away compared to your L/R, it will set a +3db trim so that your center gets a slight bit more voltage going to it.

Hell, never mind sensitivity, some people

1) Have their centers hooked up to the receiver's amp and the L/R mains hooked up to a separate receiver (although I'd personally look for a 3ch amp for the whole front soundstage)
2) have a tonally matched center with much lower impedance. IE Usher S525 (4 ohm nominal) and S520(8ohm nominal).

That center is 88 dB @ 1 watt / 1m
86 dB @ 1 watt / 1m

However that so-called sensitivity spec above as it is written is an efficiency spec, not sensisitivy (which would db/ 2.83V rms / 1 m).

In other words, the stereo pair is getting a current of 0.35 amperes for a power of 1 watt in order to get 86 db and the center is getting a current of .50 and a voltage of 2.0 V to get 88db. On THAT note though, the above sensitivity could just be improperly labeled. In that case, it should have been in db/2.83V rms / 1m in the first place.

OTHERWISE, when the receiver sends a test tone to each speaker, the center will probably sound reasonably louder than the stereo pair, however it will also put more stress on the receiver's amp section in the process.

That's why some amps might be listed at 200w @ 8 ohm and 400w @ 4 ohm - the output voltage would be the same though! Er I just went off on a tangent there.

My point is, even identically matched center speakers can vary significantly from the mains and surrounds in the same line - but level matching solves that. Just make sure that every speaker you plan to use - not JUST the mains - has a nominal impedance your receiver/amp can handle.

 

[jp_over]

a bit farther

The important thing is a center that's tonally matched (same crossover frequency and drivers) and ideally you want it to be the exact same speaker, but...

As long as it has Auto-calibration, your surround receiver or prepro will set channel trims based on the distance and sensitivity.

So if your center is 3db too quiet at 12 ft away compared to your L/R, it will set a +3db trim so that your center gets a slight bit more voltage going to it.

Hell, never mind sensitivity, some people

1) Have their centers hooked up to the receiver's amp and the L/R mains hooked up to a separate receiver (although I'd personally look for a 3ch amp for the whole front soundstage)
2) have a tonally matched center with much lower impedance. IE Usher S525 (4 ohm nominal) and S520(8ohm nominal).

That center is 88 dB @ 1 watt / 1m
86 dB @ 1 watt / 1m

However that so-called sensitivity spec above as it is written is an efficiency spec, not sensisitivy (which would db/ 2.83V rms / 1 m).

In other words, the stereo pair is getting a current of 0.35 amperes for a power of 1 watt in order to get 86 db and the center is getting a current of .50 and a voltage of 2.0 V to get 88db. On THAT note though, the above sensitivity could just be improperly labeled. In that case, it should have been in db/2.83V rms / 1m in the first place.

OTHERWISE, when the receiver sends a test tone to each speaker, the center will probably sound reasonably louder than the stereo pair, however it will also put more stress on the receiver's amp section in the process.

That's why some amps might be listed at 200w @ 8 ohm and 400w @ 4 ohm - the output voltage would be the same though! Er I just went off on a tangent there.

My point is, even identically matched center speakers can vary significantly from the mains and surrounds in the same line - but level matching solves that. Just make sure that every speaker you plan to use - not JUST the mains - has a nominal impedance your receiver/amp can handle.

Outstanding post. Can we take this a bit farther while still staying somewhat in line with the OP's question? Say for instance using the B&W 802D & the HTM4D. The 802D can handle up to 500 watts & the other up to 120 watts. Regardless of sensitivity, how can one overcome the vast difference in power handling (short of purchasing a bigger center in the 800 series)? Or is this a silly question since one should use a center with closer wattage rating from the same line?

Thanks!

 

[3db]

How close do the sensitivity ratings need to be for the front vs. center channel speaker? I am considering using a 89db sensitivity rated speaker for the center channel, that would be matched up (same brand, similar drivers, etc) with 92db sensitivity rated fronts? Thanks.

As long as your with the same manufacturer and possbibly the same line, there will be no issue as most AVRs now have auto room correction firmware built in that will compensate for frrquency and level discrpeancies caused by speaker room intercatrion. Even if your AVR is not blessed with the auto setup feature, you'll be able to manually set the output level for the center channel to match tht of your left/right mains.

 

[j_garcia]

Yes, what 3dB said - the speaker sensitivity doesn't matter if you are calibrating, because they will all be set to the same output level for your listening position.

 

[TLS Guy]

Outstanding post. Can we take this a bit farther while still staying somewhat in line with the OP's question? Say for instance using the B&W 802D & the HTM4D. The 802D can handle up to 500 watts & the other up to 120 watts. Regardless of sensitivity, how can one overcome the vast difference in power handling (short of purchasing a bigger center in the 800 series)? Or is this a silly question since one should use a center with closer wattage rating from the same line?

Thanks!

No its not a silly question.

As I have so often stated before, the center speaker is a huge problem. Unless you use a transparent screen and projector, your space for a center is limited. Yet the speaker is called on for heavy duty and must be an excellent speaker with good voice clarity. In my view it also needs a cone dispersion patter over the listening area so as not to interfere with the mains.

In addition the speaker must create a good coherent sound source and lock the voices to the screen.

It is a really tall order. It is not surprising that most centers come up way short of the mark.

 

[tom67]

Center

How close do the sensitivity ratings need to be for the front vs. center channel speaker? I am considering using a 89db sensitivity rated speaker for the center channel, that would be matched up (same brand, similar drivers, etc) with 92db sensitivity rated fronts? Thanks.

Surprised, usually same brand (assuming same series also) have the same DB or center 1DB higher...I experimented with large Klipsch center and Kef fronts that were 7DB apart and no problem, but had to reduce center volume considerably...I would think it would be more of a problem with music than HT....In any event, not the ideal...I'm assuming you can get a real good deal to consider this...

 

[zumbo]

Outstanding post. Can we take this a bit farther while still staying somewhat in line with the OP's question? Say for instance using the B&W 802D & the HTM4D. The 802D can handle up to 500 watts & the other up to 120 watts. Regardless of sensitivity, how can one overcome the vast difference in power handling (short of purchasing a bigger center in the 800 series)? Or is this a silly question since one should use a center with closer wattage rating from the same line?

Thanks!

Separate 2-channel amp for the 802D. Recalibrate system.

5-channel amp for all three speakers. Bi-amp the 802s with 4-channels, and use the fifth for the center. Recalibrate.

 

[j_garcia]

Outstanding post. Can we take this a bit farther while still staying somewhat in line with the OP's question? Say for instance using the B&W 802D & the HTM4D. The 802D can handle up to 500 watts & the other up to 120 watts. Regardless of sensitivity, how can one overcome the vast difference in power handling (short of purchasing a bigger center in the 800 series)? Or is this a silly question since one should use a center with closer wattage rating from the same line?

Thanks!

My guess is that center probably doesn't NEED that much power to achieve the same SPL as the 802s. Presumably we are talking about the 802s wanting that kind of power when run full range, but with them set to small with a sub, they probably don't require that much power either to achieve good SPLs.

The discrepancy between what they can handle is also sort of irrelevant unless you are planning on actually hooking up 500W to the center and playing at 100% output. Just because a speaker says it can handle 500W doesn't mean you need 500w to drive it all the time.

At the same time, for a seemless stage, the center should be a timbre match for the mains so it should already be from the same product line ideally, irrespective of power requirements.

 

[jp_over]

Thanks for the responses friends.

It sounds like what I need to do is demo the 802D with the HTM4 to see if it's a good match with some prerecorded media of choice (news, movie clips, etc). If I choose this set up, I believe an Emotiva XPA 3 would be a good compromise on power / power handling understanding that the receiver would give some ability to make adjustments.
I would love to have 3 x 802s to provide the ultimate match-up as Dr. Mark recommends and I know this is the best choice.

Yet I only want the center to match sound/output for medium to low-level, uber-clear dialogue, TV/news watching. Plus of course center channel size is a factor such that it will fit in the entertainment center. Otherwise, I’d look more closely at the HTM2 & perhaps mount the TV to the wall giving me the ability to put the center on top of the entertainment center.

For music (a bit louder listening at times), I would use the L & R only (don't plan on purchasing surrounds at all). Being military, I can’t factor room size/acoustics since we move every 3 years or so. Ah, decisions.

Hope I didn’t derail the OP’s post too much!

 

[Theresa]

Don't need rating

Don't be fooled by sensitivity ratings, they are inaccurate more often than not. The level can be adjusted for all channels on most receivers/pre-pros. I have L/Rs DIY with the woofer rated at 87db for the center and the R/Ls 89db. I do use electronic/DSP crossovers though and have tweaked most parameters a lot. They end up being almost exactly the same sensitivity. Can you believe that 90% of speakers are 90db/2.83v? I don't, they use vastly different drivers in different configurations. Its just marketing. Most are quite a bit less than their rating.

 

[Pyrrho]

How close do the sensitivity ratings need to be for the front vs. center channel speaker? I am considering using a 89db sensitivity rated speaker for the center channel, that would be matched up (same brand, similar drivers, etc) with 92db sensitivity rated fronts? Thanks.

The relative sensitivity does not matter at all, as long as your receiver/preamp can adjust sufficiently to compensate for the difference.

 

[j_garcia]

Don't be fooled by sensitivity ratings, they are inaccurate more often than not. The level can be adjusted for all channels on most receivers/pre-pros. I have L/Rs DIY with the woofer rated at 87db for the center and the R/Ls 89db. I do use electronic/DSP crossovers though and have tweaked most parameters a lot. They end up being almost exactly the same sensitivity. Can you believe that 90% of speakers are 90db/2.83v? I don't, they use vastly different drivers in different configurations. Its just marketing. Most are quite a bit less than their rating.

Huh? While different manufacturers may measure differently, the reported sensitivity of a speaker is far from marketing hype.

 

[zieglj01]

Huh? While different manufacturers may measure differently, the reported sensitivity of a speaker is far from marketing hype.

I have owned and listened to a lot of speakers, and they seem
to be real close, with their stated sensitivity specs.

 

[zumbo]

.

Man, what has happened to the forum? I have been out-of-pocket due to all the bad post. Decided to check-in, and it seems to have gotten a whole lot worse.

Since when can someone measure sensitivity by listening?

 

[TLS Guy]

Man, what has happened to the forum? I have been out-of-pocket due to all the bad post. Decided to check-in, and it seems to have gotten a whole lot worse.

Since when can someone measure sensitivity by listening?

You have that right. We have been awash in nonsense lately.

However there are two ways of specifying sensitivity and they are not the same unless the speaker presents an almost resistive 8 ohm load.

We have ratings at 1 watt 1 meter and 2.8 volts 1 watt one meter. 2.8 volts delivers 1 watt into an 8 ohm load, but obviously more into a lower impedance.

 

[lsiberian]

No its not a silly question.

As I have so often stated before, the center speaker is a huge problem. Unless you use a transparent screen and projector, your space for a center is limited. Yet the speaker is called on for heavy duty and must be an excellent speaker with good voice clarity. In my view it also needs a cone dispersion patter over the listening area so as not to interfere with the mains.

In addition the speaker must create a good coherent sound source and lock the voices to the screen.

It is a really tall order. It is not surprising that most centers come up way short of the mark.

Are co-axials the best drivers for a center in most situations?

 

[TLS Guy]

Are co-axials the best drivers for a center in most situations?

Probably. However a center is a good indication for a three way, like the B & Ws. I would like to get my hands on the modified ATC mid dome for PMC and make an active center. That mid can handle the entire speech discrimination band with ease, and power to spare.