Understanding specs... - AVS Forum
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post #1 of 15 Old 04-10-2012, 03:35 PM - Thread Starter
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I`m not certain what to make of this,

Enclosure Type: 2-Way reflex, loaded
Frequency Response -6dB: 35Hz - 20kHz
Sensitivity SPL/M @ 2.83V: 91dB
Impedance: 8 ohms, min. 4.6 ohms
Bass/Mid Unit: 2 x 5.9in
Frequency Response Curve: 35Hz - 20kHz
Audio Sensitivity: 91 dB
Impedance: 8 ohm

Could somebody elaborate on the bold character, is this good or bad?

cheers
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post #2 of 15 Old 04-10-2012, 03:52 PM
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Quote:
Originally Posted by jproy13 View Post

Frequency Response -6dB: 35Hz - 20kHz

Frequency response numbers mean nothing without the +/- dB range. This means that the response rolls off by more than 6 dB as you go below 35 Hz and higher than 20 KHz. 35 Hz is solid response (not sub-like, but solid for a speaker). The numbers lacks a + number on that dB range.

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post #3 of 15 Old 04-10-2012, 06:31 PM - Thread Starter
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Quote:
Originally Posted by psgcdn View Post

Frequency response numbers mean nothing without the +/- dB range. This means that the response rolls off by more than 6 dB as you go below 35 Hz and higher than 20 KHz. 35 Hz is solid response (not sub-like, but solid for a speaker). The numbers lacks a + number on that dB range.

thanks. kind of what I was thinking, just wasn't sure why the "+" would have been omitted. Thought it meant something different.

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post #4 of 15 Old 04-10-2012, 06:46 PM
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I have a different interpretation of that spec. I think it means that the response between 35 and 20kHz varies between 0 and -6db off of the max. Or in other words any trough would be no more than -6db from the max.
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post #5 of 15 Old 04-10-2012, 07:26 PM
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Quote:
Originally Posted by C0rk View Post

I have a different interpretation of that spec. I think it means that the response between 35 and 20kHz varies between 0 and -6db off of the max. Or in other words any trough would be no more than -6db from the max.

I doubt that. It would be described as +0db/-6db to define the envelope. The original spec has no such envelope and simply means that the speaker is down 6db at 35Hz and at 20kHz with respect to an undefined (but usually 1kHz) reference frequency and under undefined conditions (anechoic?). Some of the other specs are redundant. Overall, not particularly informative, even in a category (speakers) where specs are usually not particularly useful.

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http://www.stereophile.com/category/music-round

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post #6 of 15 Old 04-11-2012, 04:25 AM
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Some are redundant, but it's nice to see the minimum impedance listed.

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post #7 of 15 Old 04-11-2012, 07:31 AM
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The -3db point is usually considered the "roll-off" point, because that is the "half-power" point, where the speaker output is only half of what it would be in the nominal operating frequency range.

The -6db point would be one-fourth power, which is pretty far down. I would look at that spec and assume that the speaker starts to roll off at about 50 Hz; that would be its approximate low frequency operating limit for linear response.

A manufacturer that gives a -6db spec is one that is not giving a standard spec, and to me that tells me they are trying to fool the unwary with that number. I would look for something from a company that gives a standard +-3db spec. for frequency response.

Where did you get those specs?






Quote:
Originally Posted by jproy13 View Post

I`m not certain what to make of this,

Enclosure Type: 2-Way reflex, loaded
Frequency Response -6dB: 35Hz - 20kHz
Sensitivity SPL/M @ 2.83V: 91dB
Impedance: 8 ohms, min. 4.6 ohms
Bass/Mid Unit: 2 x 5.9in
Frequency Response Curve: 35Hz - 20kHz
Audio Sensitivity: 91 dB
Impedance: 8 ohm

Could somebody elaborate on the bold character, is this good or bad?

cheers

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post #8 of 15 Old 04-11-2012, 07:51 AM
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Myself I would not consider a speaker with a +/- 6db spec. I believe the industry standard is +/-3 db for an acceptable rating.
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post #9 of 15 Old 04-11-2012, 08:25 AM
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Sensitivity SPL/M @ 2.83V: 91dB
using this method makes the sensitivity higher than what it actually is, using 2.83V adds 3db to the SPL, 1m/1w it would only be 88db.
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post #10 of 15 Old 04-11-2012, 01:26 PM
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Quote:
Originally Posted by gtpsuper24 View Post

Sensitivity SPL/M @ 2.83V: 91dB
using this method makes the sensitivity higher than what it actually is, using 2.83V adds 3db to the SPL, 1m/1w it would only be 88db.

No, it's 1 watt if the load is 8 ohms.

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post #11 of 15 Old 04-11-2012, 04:05 PM - Thread Starter
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^^^^^^
thank you everybody for your inputs. Your various inputs is the reason I asked the question. I was also weary of these type of specs and my gut feeling told me to ask first.

@commsysman, they're the specs of the Mission MV line which is discontinued I believe.

Like I've said in another thread, the only "real" speakers I've ever owned are the ones I have now (Athena Audition series, F2, F1, B1 & the C1) and I'm just playing with the idea.

I think I will abandoned the idea of these particular ones.

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post #12 of 15 Old 04-11-2012, 04:55 PM
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Quote:
Originally Posted by gtpsuper24 View Post

Sensitivity SPL/M @ 2.83V: 91dB
using this method makes the sensitivity higher than what it actually is, using 2.83V adds 3db to the SPL, 1m/1w it would only be 88db.

Actually the voltage spec is a better way of specing sensitivity.

No manufacturer delivers "constant power" to a loudspeaker. They only deliver a constant voltage. The actual wattage would be different at different freq. due to the different impedances at different freq.

The "wattage" could be figured out any of different ways. Do you use the rated 8 ohm impedance? or the minimum impedance? Or some sort of "average"? impedance.

The 1 watt spec (while a standard-kinda) is often interesting.

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post #13 of 15 Old 04-12-2012, 08:39 AM
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That is incorrect. There is no 3db addition.

2.83V across an 8 ohm speaker results in One Watt of power being delivered to the speaker. Do the math.

(The formula to calculate that is; POWER = V squared divided by Z.)

If the speaker is NOT 8 ohms, then a different voltage must be used to test it at one watt of power. For a 4 ohm speaker, 2.0 V is the required voltage to apply one watt of power.

The standard test measurement is to apply one watt of power to the speaker and measure the SPL at a distance of one meter from the speaker; xx db/w/m.

Since 1 KHz is usually used, one should know the exact impedance of the speaker at 1 KHz and use that to calculate the exact voltage required for one watt of power.



Quote:
Originally Posted by gtpsuper24 View Post

Sensitivity SPL/M @ 2.83V: 91dB
using this method makes the sensitivity higher than what it actually is, using 2.83V adds 3db to the SPL, 1m/1w it would only be 88db.

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post #14 of 15 Old 04-12-2012, 03:56 PM - Thread Starter
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^^^^
sooooo, we're saying that the speakers with these particular specs are krap?
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post #15 of 15 Old 04-12-2012, 04:08 PM
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Quote:
Originally Posted by jproy13 View Post

^^^^
sooooo, we're saying that the speakers with these particular specs are krap?

No. At least "we" shouldn't be. You can't say that based upon those specs alone. And to argue that they are crap simply because they state a -6dB point instead of a -3dB point is more than a stretch.

"All men are frauds. The only difference between them is that some admit it. I myself deny it."
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