Bigger speakers = smaller sound? - AVS Forum
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post #1 of 16 Old 12-19-2013, 09:59 AM - Thread Starter
 
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I've recently replaced my B&W CM2's with CM9's in my 2ch room. The CM9's sound great, but at the same volume they're quite a bit softer than the CM2's. I'm assuming this is because the CM9's require more power to drive more drivers or something along those lines?

The main thing I'm trying to figure out here is, if I buy a power amp, will that fix the issue? Seems logical to me?

Current amp is a Marantz SR6003, 110W, 7.1 channels, of which 5.1 are currently hooked up.

Any advice?
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post #2 of 16 Old 12-19-2013, 10:38 AM
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Did you calibrate the speakers?

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post #3 of 16 Old 12-19-2013, 10:43 AM
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Is something keeping you from turning the volume control up?
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post #4 of 16 Old 12-19-2013, 11:03 AM
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Quote:
Originally Posted by OllieS View Post

I've recently replaced my B&W CM2's with CM9's in my 2ch room. The CM9's sound great, but at the same volume they're quite a bit softer than the CM2's. I'm assuming this is because the CM9's require more power to drive more drivers or something along those lines?

The main thing I'm trying to figure out here is, if I buy a power amp, will that fix the issue? Seems logical to me?

Current amp is a Marantz SR6003, 110W, 7.1 channels, of which 5.1 are currently hooked up.

Any advice?

Both the CM2 and CM9 speakers have 89 dB/W sensitivity which means that they should be equally loud with equal power.


There are also B&W CM2 speakers in the Concept 90 line which are different. Which CM2s do you have?
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post #5 of 16 Old 12-20-2013, 10:33 AM
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The 110W spec is ONLY for the case where ONLY 2 channels are driven. Any idea that it can deliver 110 watts to all five or 7 channels is a fantasy. It ain't gonna happen.

When driving 5 speakers, it should be able to provide around 50-60 watts per channel or so. Maybe.

That's not the problem though. The impedance of the CM9 speakers goes as low as 3 ohms at some frequencies. The Marantz 6003 is not designed for that type of load and is struggling.

Using the preout jacks for the front two channels, you should buy a Marantz MM7025 power amplifier and use it to drive the CM9 front speakers.

That will take care of your problem nicely. Its two channels have more speaker drive capability than your whole receiver.

It can drive the CM9 speakers properly, and then the receiver will only have to drive the other 3 speakers.

Or, for the same money, you could get the Emotiva XPA-3 amplifier, and use it to drive the front 3 channels, and the receiver would only drive the other two (it has 200 watts per channel, so that would be very nice).
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post #6 of 16 Old 12-20-2013, 11:06 AM
 
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That's not the problem though. The impedance of the CM9 speakers goes as low as 3 ohms at some frequencies. The Marantz 6003 is not designed for that type of load and is struggling.

Makes sense. Thanks for the advice!
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post #7 of 16 Old 12-20-2013, 11:24 AM
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Quote:
Originally Posted by commsysman View Post

The 110W spec is ONLY for the case where ONLY 2 channels are driven. Any idea that it can deliver 110 watts to all five or 7 channels is a fantasy. It ain't gonna happen.

When driving 5 speakers, it should be able to provide around 50-60 watts per channel or so. Maybe.

That's not the problem though. The impedance of the CM9 speakers goes as low as 3 ohms at some frequencies. The Marantz 6003 is not designed for that type of load and is struggling.

Using the preout jacks for the front two channels, you should buy a Marantz MM7025 power amplifier and use it to drive the CM9 front speakers.

That will take care of your problem nicely. Its two channels have more speaker drive capability than your whole receiver.

It can drive the CM9 speakers properly, and then the receiver will only have to drive the other 3 speakers.

Or, for the same money, you could get the Emotiva XPA-3 amplifier, and use it to drive the front 3 channels, and the receiver would only drive the other two (it has 200 watts per channel, so that would be very nice).

WRONG!! Since you so often base your reviews on what you READ and not on actual use I'm surprised you
Missed this from "Sound & Vision"


http://www.soundandvision.com/content/marantz-sr6003-av-receiver-page-2
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post #8 of 16 Old 12-20-2013, 12:59 PM
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Quote:
Originally Posted by commsysman View Post

The 110W spec is ONLY for the case where ONLY 2 channels are driven. Any idea that it can deliver 110 watts to all five or 7 channels is a fantasy. It ain't gonna happen.

When driving 5 speakers, it should be able to provide around 50-60 watts per channel or so. Maybe.
And the only time an AVR will be required to output full power on all channels at the same time will be when testing for this using tones or noise. Under normal operating conditions it is a furphy.
Even if there were a rare event where all channels did output a full level signal simultaneously, then 110 to 60W is just under 3dB and unlikely to be heard as a transient condition.
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post #9 of 16 Old 12-20-2013, 01:55 PM
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Quote:
Originally Posted by commsysman View Post

The 110W spec is ONLY for the case where ONLY 2 channels are driven. Any idea that it can deliver 110 watts to all five or 7 channels is a fantasy. It ain't gonna happen.

Let us be frank about this. This entire test is not representative of what the AVR will do with music since music always has a much higher crest factor than the pure sine waves used for this particular test.
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When driving 5 speakers, it should be able to provide around 50-60 watts per channel or so. Maybe.

Again only true for sine waves into a resistive load on a test bench. With speakers and playing music the power output during muscial peaks will be much more.
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That's not the problem though. The impedance of the CM9 speakers goes as low as 3 ohms at some frequencies. The Marantz 6003 is not designed for that type of load and is struggling.

Same problem as above. The Marantz may struggle when delivering pure sine waves to resistive loads, but real world 4 ohm speakers are far easier to drive.

If you ever compare how an amplifier works when driving peak power into speakers to load resistors, you will find that the speakers take a lot less "grunt" to drive than speakers. Obvioiusly, you haven't because of the questionable information that you are posting.

I don't happen to have CM9s right here, but I do have Primus P363s that share the characteristic of an impedance curve that drops below 4 ohms at some frequencies in the mid-bass. About the same efficiency, too. They just aren't a problem for my garden variety AVR, a Denon 1913.
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post #10 of 16 Old 12-20-2013, 01:56 PM
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Quote:
Originally Posted by Heinrich S View Post

Quote:
That's not the problem though. The impedance of the CM9 speakers goes as low as 3 ohms at some frequencies. The Marantz 6003 is not designed for that type of load and is struggling.

Makes sense. Thanks for the advice!

Actually, it makes no sense. See my other post, above.
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post #11 of 16 Old 12-20-2013, 02:03 PM
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Originally Posted by FMW View Post

Is something keeping you from turning the volume control up?

Funny, but very relevant question. Seems that even though both speakers have the same sensitivity spec, they are not equally sensitive in your room. So why not just turn the volume up a little more?

For every new thing I learn, I forget two things I used to know.
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post #12 of 16 Old 12-20-2013, 02:36 PM
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Originally Posted by arnyk View Post

Actually, it makes no sense. See my other post, above.

+1
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post #13 of 16 Old 12-21-2013, 03:21 PM
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Originally Posted by arnyk View Post

Both the CM2 and CM9 speakers have 89 dB/W sensitivity which means that they should be equally loud with equal power.

If only it was that easy.

Yes the "ratings" maybe the same-but where did the ratings come from?

Is it with the same input signal ( either 1 watt or 2.83V?) That could make a difference-DON'T ASSUME it was the same input.

Next what does the number actually mean? Is it an average across the freq range or some peak in the response? That could also make a big difference in how loud the different speakers "appear" to be.

A simple number will result in a easy to understand WRONG answer. You HAVE to look at a MEASURED response curve to get a real idea of what the ACTUAL SPL is.

That-and knowing what the drive signal is.

I prefer the 2.83V input because you CANNOT drive a loudspeaker with 1 Watt. If you look at the impedance cure you will see that the ACTUAL power will be all over the map with the same input VOLTAGE.
The 1 W rating comes from a 2.83V input into an "assumed" 8 ohm loudspeaker. If the speaker is not exactly 8 ohms (they are not-despite what the spec sheet says), the the actual power will be different.

Just sayin' that it is not always that simple.

So between possibly a different input voltage and where the response was measured, you could have very different actual SPL.

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post #14 of 16 Old 12-21-2013, 04:06 PM
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Quote:
Originally Posted by Ivan Beaver View Post

Quote:
Originally Posted by arnyk View Post

Both the CM2 and CM9 speakers have 89 dB/W sensitivity which means that they should be equally loud with equal power.

If only it was that easy.

Yes the "ratings" maybe the same-but where did the ratings come from?

Manufacturer's spec sheets oh his web site, roughly contemporaneous
Quote:
Is it with the same input signal ( either 1 watt or 2.83V?) That could make a difference-DON'T ASSUME it was the same input.

If memory serves, 2.83 was the reference for both speakers.
Quote:
Next what does the number actually mean? Is it an average across the freq range or some peak in the response? That could also make a big difference in how loud the different speakers "appear" to be.

One would think that the vendor would be consistent.
Quote:
A simple number will result in a easy to understand WRONG answer. You HAVE to look at a MEASURED response curve to get a real idea of what the ACTUAL SPL is.

The vendor has a reputation for being able walk and chew gum at the same time...

These aren't exactly white van speakers!
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post #15 of 16 Old 12-21-2013, 08:45 PM
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Originally Posted by OllieS View Post

I've recently replaced my B&W CM2's with CM9's in my 2ch room. The CM9's sound great, but at the same volume they're quite a bit softer than the CM2's. I'm assuming this is because the CM9's require more power to drive more drivers or something along those lines?

The main thing I'm trying to figure out here is, if I buy a power amp, will that fix the issue? Seems logical to me?

Current amp is a Marantz SR6003, 110W, 7.1 channels, of which 5.1 are currently hooked up.

Any advice?

Call B&W customer service and ball them out.

Just kidding. I would be surprised if an objective measure revealed any difference between the speakers. Could very well be your imagination.

Given the lower frequency capability of the CM9 floor standing model (30Hz) as opposed to the CM2's bookshelf (65hz), midrange and high frequencies may seem softer due to the presence of deeper bass.

If not a perceptual inaccuracy the lower volume could be attributed to AVR EQ adjustments

Might be useful for recommendations to know if a sub is used, and the crossover setting, but, not nearly as useful as a SPL measurement.
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post #16 of 16 Old 12-22-2013, 06:07 AM
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Originally Posted by arnyk View Post

Manufacturer's spec sheets oh his web site, roughly contemporaneous
If memory serves, 2.83 was the reference for both speakers.
One would think that the vendor would be consistent.
The vendor has a reputation for being able walk and chew gum at the same time...

These aren't exactly white van speakers!
I was not so much talking about the specific speakers in the post (although it may have sounded/looked like that), but making more "general" comments about specs and how they are presented from manufacturers.

You could take the same measured graph of a single product, and give it to a number of different people and come up with pretty different "specs". It just depends on what information the person in trying to present. Is it a marketing guy or a guy (like me) who tries to give useful information as to what the customer could expect out of the product, and the user would be able to get the same results in their own backyard-not using some specilized test gear/test tones etc.

The nice thing about standards is that there are so many to choose from
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