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Discussion Starter · #1 ·
Im trying to learn how to properly match speakers... where does freq response fit in? Should every speaker (front, center and surround) have the same? What is an acceptable difference? In the system Im looking at, the center has 100-20,000 Hz (-3dB), while the fronts have 48-24,000 Hz (-3dB).
 

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The FR specs you get from the manufacturers are grossly inadequate for matching.


Kal
 

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Discussion Starter · #3 ·
Well, is there some difference threshold I should look for even with their "grossly inadequate" numbers? :)


The speakers are all the same brand (in this case, Polk).
 

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If you are matching for timbre, the numbers won't help you. What are you trying to achieve?


Kal
 

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Discussion Starter · #5 ·
I was curious as to if the freq response nummbers did matter for one.


Timbre is another thing Im curious about, not sure how to go about matching that.
 

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Quote:
Originally Posted by aegisx
Im trying to learn how to properly match speakers... where does freq response fit in? Should every speaker (front, center and surround) have the same? What is an acceptable difference? In the system Im looking at, the center has 100-20,000 Hz (-3dB), while the fronts have 48-24,000 Hz (-3dB).
aegisx,


The LFE will be brick walled at 120hz, and the surronds in a ideal setup will be full range/

or good midfield monitors. All should be identical make/model.


The LFE uses a offset in (dolby) specs. without bass managment will add 10db effective headroom with 115 dBspl peak info. The (5) surrounds 105dBspl peak.


Also dolby specs. the (5) in 5.1 at 85dBspl or 79dBspl for film released mastered DVD's

I think the (-3dB) you are refereing to is the mix manager or offset that is used on the pro encode side that becomes the meta data your DD decoder uses to scale the sounds level ie [-20dBsfs=0VU=+4dBu] or (-10dBV) for consumer (RCA CNN) on analog output .


editing/
 

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Discussion Starter · #7 ·
Thanks for the reply, sadly most of it was above my head.


These are all the same make (Polk). Their freq response differs... so Im trying to learn what is an unacceptable difference, so that I can easily weed out certain ones.
 

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The difference isnt that important.


You do want good frequency response *in general*.


My better speakers tend to go down to around 50hz or 60hz , and up to 20 Khz or 30khz
 

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Aegisx,

Here is you correction numbers for the Radio Shack Meter..

Hope this helps.

Lee


10Hz add 20dB

12Hz add 16.5dB

16Hz add 11.5dB

20Hz add 7.5dB

25Hz add 5dB

31.5Hz add 3dB

40Hz add 2.5dB

50Hz add 1.5dB

63Hz add 1.5dB

80Hz add 1.5dB

100Hz add 2dB

125Hz add .5dB
 

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aegisx, the only way to ensure that your speakers are timbre matched is to use exactly the same speaker in all positions. The next best way is to get all your speakers from the same manufacturer. Speakers with differing shapes and internal volumes, such as your typical setup of main speakers, center channel speaker, and surround speakers, are going to sound different from each other. But if they come from the same manufacturer, you may assume that he has matched the voicing (timber matched) as closely as is possible. Close enough that any small differences which remain will not be distracting.


I suppose it is possible to timbe match speakers from different manufacturers, but I sure wouldn't know how to go about it. I don't think you can use frequency response alone to do it.
 

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aegisx, the only way to ensure that your speakers are timbre matched is to use exactly the same speaker in all positions. The next best way is to get all your speakers from the same manufacturer. Speakers with differing shapes and internal volumes, such as your typical setup of main speakers, center channel speaker, and surround speakers, are going to sound different from each other. But if they come from the same manufacturer, you may assume that he has matched the voicing (timber matched) as closely as is possible. Close enough that any small differences which remain will not be distracting.


I suppose it is possible to timbe match speakers from different manufacturers, but I sure wouldn't know how to go about it. I don't think you can use frequency response alone to do it.
 

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Frequency response is an indication of the speaker's ability to reproduce the complete range of audio frequencies which is roughly 20 Hz to 20 kHz. Ideal speakers would be able to reproduce the entire range without variation in loudness at any frequency. If you graphed its frequency response, it would be a horizontal, straight line. For many reasons, this is impossible. So manufacturers give frequency response with a range of loudness, i.e. plus or minus so many dB. The smaller this number, the flatter the frequency response, the better. If you were to graph a real speaker's response, it would typically look like a ragged curve, not a straight line.


Two different model speakers with the same frequency response numbers generally will not sound the same. They are an infinite number of ways to draw a ragged curve between 20 Hz and 20 kHz if the curve can vary in amplitude by plus or minus, say, 3 dB. The difference in the frequency response curves translates into a difference in what is called timbre, or voice. Suffice it to say that differences in components, materials and design will make difference speakers sound different. For a good match, it is generally necessary to use speakers from the same manufacturer and line. At the risk of over simplifying, they pretty much need to use the exact same, tweeter, squawker, crossover network, and a woofer that is similar if different in size to have the same timbre.


The big question is how sensitive are you to differences in timbre. I find small differences noticeable and annoying in my HT system. Some folks report that they don't notice much larger differences.


BTW nowadays, just about all decent speakers will reproduce 20 kHz without a problem. And most folks cannot even hear a frequency that high anyway. The area in which many speakers lack is the low end. However, if your speakers are down by no more than, say, 3 dB at 80 Hz, you are fine. Just add a good subwoofer.
 

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Discussion Starter · #13 ·
THX says (as I mentioned in another post) that they can process a signal so the timbre will be the same for front and rear. Is this just hype or does it actually help?
 

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Quote:
Originally Posted by aegisx
THX says (as I mentioned in another post) that they can process a signal so the timbre will be the same for front and rear. Is this just hype or does it actually help?
I think you are refereing to the speaker "size" setting..this option does work. One must consider if he/she is using bass managment.


Also, I correccted my earlier post, I meant to say it's the LFE with the +10dB gain added to the sub woffer. Check dolby's web site for they explain the "speakers size"

condition as it relates to bass managment>


thomas
 

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Timbre matching is something that is most easily done by your own ears. When you have a pink noise test signal that switches around the room from one speaker to the next, it will be painfully obvious when speakers have different timbre from one to the next. Typically, as long as you buy speakers from the same model line of a manufacturer, timbre matching isn't that big of an issue. Some manufacturers do it better than others but most competent speaker manufacturers these days will have fairly well matched timbre for their front and center speakers. Rear speaker timbre matching is not as easily done since many manufacturers design their rear surround speakers differently from their front speakers. Placement is also a big issue, since rear speakers are placed in a completely different part of the room where the room accoustics can be very different from where the front speakes are. However, it's good that timbre matching between rear and front speakers are not as critical and you are likely listening to the rear speakers off-axis anyway.


So just buy speakers that are from the same model line, try out as many practical speaker placements as possible to get the most even timbre across the speakers. Other than that, cross your fingers and hope for the best.
 

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Discussion Starter · #16 ·
From what I read, it sounds like the matching is most important with the fronts and center... and not as with the surrounds. Would this be a correct thought?
 
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