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Beyerdynamic T90 Discussion and Support Thread - Page 114

post #1696 of 4019
Quote:
Originally Posted by atomicbob View Post

Your Valhalla is capable of outputting 420mW into 300 ohms at full volume. The dt770 have a sensitivity of 96dB/mW. When turned to max volume on the Valahalla you are getting 122 dB SPL on the peaks. That is pretty LOUD by the way. Now the T90 have a sensitivity of 102 dB/mw which means they reach their maximum volume of 125 dB SPL peak much faster, at 200mW. I would guess that the Valhalla may reach 200mW somewhere around mid volume. That is pretty LOUD by the way. The drivers in the T90 are being overdriven above that volume and will sound terrible. That is my guess.

Ahhh ok, thank you so much for your response. Forgive my ignorance, I am new to this whole thing and still learning smily_headphones1.gif That makes a lot of sense. I'll just play them at a volume before distortion.
post #1697 of 4019

Please be careful!!

 

Your ears are very sensitive and loud volumes will cause hearing loss over time.....

 

A.

post #1698 of 4019
Quote:
Originally Posted by adydula View Post
 

Please be careful!!

 

Your ears are very sensitive and loud volumes will cause hearing loss over time.....

 

A.

What adydula said!!!!!

 

Probably time for a reminder. From the US Occupation Safety and Health Agency:

 

        TABLE G-16 - PERMISSIBLE NOISE EXPOSURES (1)
______________________________________________________________
                            |
  Duration per day, hours   | Sound level dBA slow response
____________________________|_________________________________
                            |
8...........................|                    90
6...........................|                    92
4...........................|                    95
3...........................|                    97
2...........................|                   100
1 1/2 ......................|                   102
1...........................|                   105
1/2 ........................|                   110
1/4  or less................|                   115
____________________________|________________________________
 Footnote(1) When the daily noise exposure is composed of two or
more periods of noise exposure of different levels, their combined
effect should be considered, rather than the individual effect of
each. If the sum of the following fractions: C(1)/T(1) + C(2)/T(2)
C(n)/T(n) exceeds unity, then, the mixed exposure should be
considered to exceed the limit value. Cn indicates the total time of
exposure at a specified noise level, and Tn indicates the total time
of exposure permitted at that level. Exposure to impulsive or impact
noise should not exceed 140 dB peak sound pressure level.

 

Headphone usage makes it very easy to expose oneself to VERY LOUD sounds. Hearing damage usually is permanent.

I was fortunate enough to meet an aide to the person that provided the input from their hearing research which was responsible for those limits. Latest research shows that those number are approximately 5 dB TOO LIBERAL. So the researcher would lower those numbers by 5 dB if you really care about your hearing.

 

Here is my personal sound level safety chart:

        PERMISSIBLE NOISE EXPOSURES - AtomicBob
______________________________________________________________
                            |
  Duration per day, hours   | Sound level dBA slow response
____________________________|_________________________________
                            |
8...........................|                    85
6...........................|                    87
4...........................|                    90
3...........................|                    92
2...........................|                    95
1 1/2 ......................|                    97
1...........................|                   100
1/2 ........................|                   105
1/4  or less................|                   110
____________________________|________________________________
post #1699 of 4019
Good info! But how does one go about applying it in practice? I'm quite conservative with the volume as I want to protect my hearing, but the problem is I have no clue as to how loud any given Db level is. How do you ensure you abide by the levels in your chart?
post #1700 of 4019

This is what I use:

 

 

The square device on the right is a Bruel & Kjaer 4231 microphone calibrator which I keep ISO-17025 calibrated via Scantek.

The Sound Level Meter was off 0.5 dB upon receipt and I brought it into tighter cal with the 4231.
Here is the website that was my inspiration and has construction details:

 

http://home.hccnet.nl/joop.nijenhuis/headwize/hpdbmtre.htm

 

Here is a closeup of my external auditory meatus located microphone mounting:

 

The material used for mechanical isolation is a soft durometer Poron product.

post #1701 of 4019

I'd be curious to know some techniques too. I don't have an actual sound level meter but there are Android apps in the play store. I've put the phone mic right next to the driver with a full 2K sine wave to check level but I'm sure that's not totally accurate. The readings I get are usually in the 70-80 range at normal listening volume.

 

How much does the sound level increase with the cups seals on one's head?

 

Edit: Musta posted that awesome setup right as I was asking the question :) How much did it cost to make that?


Edited by FunyunBreath - 2/14/14 at 11:02am
post #1702 of 4019

Here are the components I used (all in USD):

 

1. Velleman AVM2050 - $41 at Amazon

2. Styrofoam wig head - $5 at Amazon

3. Wood base - $10 from a craft store

4. Dowel - $2 from a craft store

5. Poron isolator - made from some sample material I received from a local distributor

 

The AVM 2050 will be close enough in calibration for general use. I'm obsessive about sound measurements, given my work in my sound lab. I also created a BlockHeadTM for use with my precision measurement microphones, but that is beyond the scope of this post. The BlockHead allows me to make NIST traceable ISO-17025 calibrated measurements. For those interested, that system uses an ACO Pacific 7046 mic capsule on a Josephson C617 mic body.


Edited by atomicbob - 2/14/14 at 11:27am
post #1703 of 4019
Quote:
Originally Posted by adydula View Post

Please be careful!!

 

Your ears are very sensitive and loud volumes will cause hearing loss over time.....

 

A.


Incidentally, I just got out of my doc's office for a hearing test after experiencing some ringing (for about a month now). According to the results, I have the ears of a 15yr old. So pheww!

It did start around the time I purchased my T90. lol

Sent from my SCH-i705 using Tapatalk
post #1704 of 4019
Quote:
Originally Posted by FrZ-Fi View Post


Any thoughts?

I'm using a Vahalla in combination with a bitfrost and I'm not experiencing any bass issues. 

post #1705 of 4019

What songs are you hearing the bass distortion on?

 

I'm amping my T90's with a bottlehead crack and I've heard some distortion in the bass and high end on a few songs at super loud volumes. I don't usually listen super loud but hey.. new headphones you gotta see just how clear and loud they can be :)

 

Specifically I can hear distortion in the beginning of Daft Punk's "Give life back to music" every time the kick hits in the first 16 seconds . Not sure if the distortion is being caused by overdriving the T90's or if they're just so revealing I'm hearing digital clipping in the recording.

 

Anyone else wanna run a little test with this track and lemme know if you get the same results?

post #1706 of 4019
Thanks guys for all your info. I don't listen to volume maxed out or even close, but I do like it loud especially with techno. Also I don't listen to my music for long durations The songs I hear bass distortion with are animals by Martin garrix and tsunami by DVBBS These are two techno flac songs I use to test the amp so far on top of some hip hip albums also in flac. On those two techno songs when the bass hits, it's distorted above a certain volume. Also I am using a Modi connected to my desktop.

When I get back from work I'll try that daft punk song.

Budhhahacker are you able reach high volumes or max volumes with out bass disortion on the t90? Can you try one of the songs I mentioned? Thanks smily_headphones1.gif
post #1707 of 4019
Quote:
Originally Posted by FrZ-Fi View Post

Guys, I got my replacement T90s in today, and I seem to still have the bass distortion issue. Above about medium volume the bass rattles and sounds garbled. I got a pair of dt 770 250ohm and they work fine even to max volume. I'm using a Modi/Valhalla combo. Any ideas?

 

I was wondering how the T90's compare in sound to the DT770's besides the bass issue you seem to be having? Which one do you think sounds better with Rock and Electronic music?

post #1708 of 4019
Quote:
Originally Posted by Matrixnobu View Post

I was wondering how the T90's compare in sound to the DT770's besides the bass issue you seem to be having? Which one do you think sounds better with Rock and Electronic music?
Quote:
Originally Posted by Matrixnobu View Post

I was wondering how the T90's compare in sound to the DT770's besides the bass issue you seem to be having? Which one do you think sounds better with Rock and Electronic music?

I havnt been able to really compare them. Will probably have a better chance this weekend.

I will say this though, the dt770 for the price is absolutely phenomenal. I have throughly enjoyed them the last two weeks, and still find it hard to believe they cost $150-$175
post #1709 of 4019

Yeah. I really am enjoying them also. Great headphones.

post #1710 of 4019

FYI, T90 for $409 with free shipping on ebay.  Bought mine from this seller.  More details in the Deals thread:

 

http://www.head-fi.org/t/692119/the-deals-discussion-thread-read-the-first-post/2985#post_10271554

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