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Headphones sensitivity, impedance, required V/I/P, amplifier gain - Page 2

post #16 of 58

Oooo, sweet thread.

 

Could you add Audio Technica's ATH-AD900X? 

 

Thanks.

post #17 of 58
Thread Starter 
Quote:
Originally Posted by ab initio View Post

Couple quick thoughts

 

1) First and foremost, thank you for this reference! 

beerchug.gif

This is extremely helpful (see below) and *should* be linked to very very often in the future.

 

2) If you are from an english-speaking country:

sed '/[0-9]\,/s/\,/./g'

 I spent 20 minutes trying to figure out how the heck the HE-6s needed 3 kW to reach 110 dB!!!

I knew they were inefficient, but I didn't think they were that bad! wink_face.gif

You're welcome and I'm sorry. Yeah the comma is our decimal separator and I totally missed it. Will change it asap.

 

 

Quote:

6) I think 110 dB is a little bit high for a reference loudness, especially since 90dB is the typical threshold for hearing damage. Because this data is especially useful for guiding newer enthusiast in their search for headphone nirvana, I think it's a little dangerous to give the impression that they should be listening at 110dB SPL with any regularity. Perhaps you could put a disclaimer in the original post warning against prolonged exposure to  >= 110 dB. Of course I'm just picking nits here.

 

110 dB is what the peaks may come near to if you turn up the volume to the max. The RMS amplitude of music is always lower than a full-scale sine wave. How much lower depends on the type of music you're listening to.

I'm still working on verifying the loudness calculations in my previous post, and I will also put up a warning.

post #18 of 58

There's something wrong there, surely the PX200s don't pull double the current of the K701s...

post #19 of 58
Thread Starter 
Quote:
Originally Posted by KamijoIsMyHero View Post

 

why? I never heard of this ideal placement for a volume pot

All analog pots suffer from some degree of channel imbalance.

Especially at low volume the imbalance is bigger, gradually decreasing with increasing volume. At 10 o'clock, if you're unlucky, you can still have 1 dB imbalance but in that case I'd consider switching the pot.

 

Rod Elliot writes:

Quote:
The gain structure of the preamp is correct when the pot spends the vast majority of its time between the 10 and 2 o'clock positions. If the volume is often below or above this range, consider changing the preamp gain.

 

If the volume control is not an analog pot and does not suffer from channel imbalance it still makes sense to have such a broad usable volume control range, because higher gain will just add more noise, distortion. The volume control will also become touchy, so turning it a bit too far in the wrong direction could hurt your hearing.

Stepped attenuators, for example, have fixed steps which you want to be able to use. Too high gain and you'll probably be forced to use some close to zero positions which are far apart in terms of step size.

With digital attenuation you will reduce the effective number of bits quite a bit. Again higher noise etc.

post #20 of 58
Thread Starter 
Quote:
Originally Posted by Meremoth View Post

Oooo, sweet thread.

 

Could you add Audio Technica's ATH-AD900X? 

 

Thanks.

I don't have measurement data on the X version, but added it based on manufacturer specifications.

 

Quote:
Originally Posted by Wildstar View Post

There's something wrong there, surely the PX200s don't pull double the current of the K701s...

You are right. I still haven't had time to double check all the numbers. The problem with the PX200 seems to be low frequency leakage and high distortion at higher levels. Changed measurement frequency to 1 kHz.

 

All these quirks are pointed out in the last "Notes" column.

post #21 of 58
Quote:
Originally Posted by xnor View Post

All analog pots suffer from some degree of channel imbalance.

Especially at low volume the imbalance is bigger, gradually decreasing with increasing volume. At 10 o'clock, if you're unlucky, you can still have 1 dB imbalance but in that case I'd consider switching the pot.

 

Rod Elliot writes:

 

If the volume control is not an analog pot and does not suffer from channel imbalance it still makes sense to have such a broad usable volume control range, because higher gain will just add more noise, distortion. The volume control will also become touchy, so turning it a bit too far in the wrong direction could hurt your hearing.

Stepped attenuators, for example, have fixed steps which you want to be able to use. Too high gain and you'll probably be forced to use some close to zero positions which are far apart in terms of step size.

With digital attenuation you will reduce the effective number of bits quite a bit. Again higher noise etc.

I'm not entirely convinced that argument is enough to have an ideal placement of 10 to 2. I might be missing some extra assumptions of the kind of amp that this ideal placement should be true of but a decent hi-fi amp shouldn't have this problem past 8-8:30 assuming 7 is the starting position.

 

For the bolded part, my amp has 2 gains available http://www.audio-gd.com/Pro/Headphoneamp/Compass%202/Compass384EN_Specs.htm and I don't hear any audible noise that changes the music. I experimented with 16 vs 24 bit and I did hear an audible difference, a bit less with 24 vs 32 bit. So based on my experiment, I think this has to do with what the DAC is like as much as the amp, I set mine to 32-bit to minimize the noise as much as possible.

post #22 of 58
Thread Starter 

If it works for you I guess it's fine.

 

The suggestion still stands though. The volume control should have a wide usable region, closer to max is better than closer to zero for reasons mentioned above.

 

I know that many headphone amps have way too high gain. That's one reason I started this thread in the first place.

post #23 of 58
Quote:
Originally Posted by xnor View Post
I know that many headphone amps have way too high gain. That's one reason I started this thread in the first place.

 

No such thing as too much gain. Gain is good. Tarzan want gain. biggrin.gif

 

se

post #24 of 58
You're dating yourself wink.gif
post #25 of 58
Thread Starter 

Sure, nothing wrong with driving PX100's with monoblocks with ~27 dB gain. 50 volts of headroom really make this headphone shine and sound better than an HD800!

post #26 of 58
Quote:
Originally Posted by vertical View Post

You're dating yourself wink.gif

 

Why not? I'm a cheap date and I put out. very_evil_smiley.gif

 

se

post #27 of 58
Quote:
Originally Posted by Steve Eddy View Post

Why not? I'm a cheap date and I put out. very_evil_smiley.gif

se
Well, I hope to never partake in the experiment to prove those claims, but am happy to attest to your sense of humor...yes, I know, a subjective opinion
post #28 of 58
Quote:
Originally Posted by Steve Eddy View Post

 

Why not? I'm a cheap date and I put out. very_evil_smiley.gif

 

se

 

"When you give to the poor, do not let your left hand know what your right is doing"

-Matthew 6:3

 

I do not mean to blaspheme in the science forum, but it was too funny I couldn't help myself!

post #29 of 58
Can you add the following headphones?

Audio Technica ATH-ANC7B (noise cancelling)
Skullcandy Aviator
Skullcandy Crushers
Skullcandy Mix Master Mike
Somic MH463
Sony MDR-XB700
Sony MDR-XB1000
Superlux HD669
Takstar Hi 2050
V-Moda Crossfade M100

The impedance of the Bose QC15 is very high...

If you don't mind me asking, how was the gain calculated? It seems to be 104 - S@1V.
Edited by HalidePisces - 6/17/13 at 9:28pm
post #30 of 58
Quote:
Originally Posted by HalidePisces View Post

If you don't mind me asking, how was the gain calculated? It seems to be 104 - S@1V.

 

The gain calculation assumes a source output voltage of 2 Vrms. For lower voltage (portable) sources, obviously more gain is needed.

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