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Old 3rd February 2004, 06:23 PM   #1
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Default 20hz-20Khz

A month ago I bought a set of Labtec headphones. On the package it read: "Frequency Response: 20hz-20Khz". Now headphones aren't like speakers where you can kind of tell by looking at them, what they're going to sound like, so I bought them. I plugged them in and played a song, there was NO low end at all. I had to turn up the equalizer +20dB @ 60hz to get any kind of bass out of them and even then, they couldn't hit 40hz for anything. Also, the ground wire came loose in the headphone. How do manufacturers get away with lying so blatantly? I'm a bit wary when I see "20hz to 20Khz" on anything. It seems that's what consumers are looking for so mfg's just stamp that on the box. It strikes me as a little odd that different speakers with different characteristics all have the same frequency response. I'm more likely to buy something that says "23hz to 24Khz (-3dB)" because to me that means the product was actually tested. Now on a more positive note, I bought a set of titanium diaphragm headphones from RadioShack with a frequency response of "15hz to 25Khz" and I was thoroughly impressed. Car manufacturers aren't allowed to publish false horsepower figures so why are makers of "subwoofers" the size of lunchboxes allowed to claim they can hit 20hz? I just sent a complaint letter to Labtec, I'm waiting for a response.
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Old 3rd February 2004, 06:33 PM   #2
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The answer is:

Labtec

Sure, it "responds" at 20Hz but not at a level you can hear. Isn't that like drivers that have a LF rating below the Fs?
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Old 3rd February 2004, 06:42 PM   #3
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I know Labtec isn't known for it's audio but that's why we have specs. The frequency response should be -3dB. NOBODY should be able to claim specs like that unless they're true.

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Sure, it "responds" at 20Hz but not at a level you can hear. Isn't that like drivers that have a LF rating below the Fs?
Well I am designing a ported box for a sub with an FS of 30 and it will have an F3 of 22hz, so it's possible sometimes. You'll definately be able to hear that. Actually in sealed boxes, the F3 is WAY above Fs.
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Old 3rd February 2004, 08:02 PM   #4
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Quote:
I know Labtec isn't known for it's audio but that's why we have specs. The frequency response should be -3dB. NOBODY should be able to claim specs like that unless they're true.
I agree. Unfortunately there's more deceptive marketing in audio than most others.

Quote:
Well I am designing a ported box for a sub with an FS of 30 and it will have an F3 of 22hz, so it's possible sometimes. You'll definately be able to hear that. Actually in sealed boxes, the F3 is WAY above Fs.
I'm thinking "free air" FR ratings. It's possible I'm thinking the wrong way here but it seems odd to rate the FR of a driver as lower than the Fs. Sure the driver responds but is it usable?
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Old 3rd February 2004, 08:44 PM   #5
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Sennheiser defines what they mean by frequency response as follows:
"Frequency response (headphones) The frequency response of a pair of headphones is given within limits defined by the manufacturer."

hehehe unfortunately they don't define what the limits are. BTW: they claim the FR of the HD650's are 10-39500 Hz.

The HeadRoom site shows measurements for a variety of headphones. Though it may be more confusing--there are graphs using various sample rates and smoothing, etc.

http://headroom.headphone.com/layout.php?topicID=10

HD600 (with heavy smoothing of the data)
Click the image to open in full size.

I've seen unsmoothed and lightly smoothed data (it looks like a roller coaster ride--same with all the other headphones, Sonys, etc.).

AKG does refer to industry standards for headband pressure and SPL rating.
http://www.akg.com/products/powersla...iew,specs.html

But no standard for FR or THD. hehehe...if anyone has a clue what usefullness 0.05% THD means (with out a specified frequency--this is for Sennheiser and yes, it's probably 1khz), I'd like to know. Is this 0.05% at only one frequency? Headphones and speakers mfgs are a bit slippery with the specs...


JF
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Old 3rd February 2004, 08:44 PM   #6
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Quote:
I'm thinking "free air" FR ratings. It's possible I'm thinking the wrong way here but it seems odd to rate the FR of a driver as lower than the Fs. Sure the driver responds but is it usable?
Well, for example, this sub's Fs is 30hz. In a sealed box, the F3 point is 55hz. In a ported one, it's about 22hz. At 22hz and 250w, the ported box should produce 121dB (8x as loud as the sealed box at that frequency), I'd say that's quite usable.

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I agree. Unfortunately there's more deceptive marketing in audio than most others.
Such blatant lies wouldn't be tolerated in any other industry, why audio then? Just because nobody complains? This isn't the first time I've been burned by false audio specs. I put together a computer system for my uncle and I bought an amplified speaker system based on specs. What I bought was supposedly 25wx2 speakers + 50w sub. The "sub" was no bigger than a chinese take-out container and couldn't hit 150hz to save its life.

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hehehe unfortunately they don't define what the limits are.
Well, RadioShack did: "15hz-25Khz (-3dB)" I'm listening to them right now and they sound great.
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Old 3rd February 2004, 09:15 PM   #7
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Quote:
Originally posted by johnferrier
Sennheiser defines what they mean by frequency response as follows:
"Frequency response (headphones) The frequency response of a pair of headphones is given within limits defined by the manufacturer."

hehehe unfortunately they don't define what the limits are. BTW: they claim the FR of the HD650's are 10-39500 Hz.
JF
I can see where the guy who purchased the Labtec's would be disappointed. Regarding the Sennheiser's, I scored a very comfortable pair of brand-new HD 470's on Ebay for less than $20. Euro-made even (Ireland). They have some pretty punchy bass for an open design. The people in the next cube over have had comments about the noise!
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Old 3rd February 2004, 10:07 PM   #8
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Quote:
Originally posted by Timn8ter
Isn't that like drivers that have a LF rating below the Fs?

The entire Bag End line of subwoofers is sealed boxes operating below the woofer's resonant frequency. Frequency response of the box/woofer is very predictable that way, and their crossovers are EQ'd to compensate...

Peace
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Old 4th February 2004, 01:57 AM   #9
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Default Re: 20hz-20Khz

Quote:
Originally posted by Solid Snake
[...] Car manufacturers aren't allowed to publish false horsepower figures so why ...
Oh but car manufacturers do lie about horsepower. I've got a car (2002 Camaro) that the manufacturer rated at 320 horsepower. They rated the same engine at 345 horsepower in a Corvette. This year's Corvettes have the same engine, but now the rating is 350 (which is about right). Next year 360?

Don't matter none to me. It still go zoom.
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Old 4th February 2004, 02:20 AM   #10
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Having the same displacement does not mean that they have the same cam or fuel and timing curves. You can buy a new computer chip to increase the power of your car.
Not necessarily a lie that the Corvette has more power.
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