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Beyerdynamic T90 Discussion and Support Thread
Feb 14, 2014 at 6:36 PM Post #1,711 of 4,487
funyunbreath said:
  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?
Click to expand...

What tubes are you using for the 12AU7 and 6080 or 6as7? Where is the volume knob set using an analog clock face as a reference from 7 o'clock to 5 o'clock? What DAC?
 
T90 on my Crack, RCA clear top 12AU7, Osram A1834, Daft Punk GLBtM first 16 seconds measures as follows:
 
o'clock
 8:00   78 dBC   68 dBA  - this is where I would normally listen
 9:00   90 dBC   80 dBA  - this was as loud as I could handle
11:00   98 dBC   88 dBA  - really LOUD
 
Now the above is only part of the information. To compare you also need to know the signal level sent by the DAC to the amp when either a 440 or 1000 Hz, 0 dBFS sine is played. In my case that has been set as follows:
 
1.005 Vrms
2.842 Vpp
2.257 dBu
 
All three mean the same thing but are different ways to represent the signal level.
 
I only listen to DP  a little, and usually with the volume much lower than others listen.
Here are some screen shots from the Digital Audio Workstation for the first 20 seconds of DP GLBtM:

Above you can see the kick hitting near the digital limits

Zoom in to see how much time is at the digital limits

Zooming in again and the left channel, while technically a few samples below the limit, does have multiple samples that are flatline. This is self imposed clipping just below the digital limits so an analysis will show no clipped samples, which indeed the DAW stats showed no clipped samples. But there is clipping below the digital limits.
 
Feb 14, 2014 at 9:50 PM Post #1,713 of 4,487
Dude! Thanks for taking all those measurements and screencaps 
beyersmile.png

 
So on my Crack I'm using a Sylvania 6SN7GT (The VT-231 military version) and a Tung Sol 5998. I also rolled a Tung Sol Mouse Ear 6SN7GT and Toshiba/Matsu****a 12au7 to see if they had the same results. All the driver tubes revealed the same distortion in the kick and cymbal hits.
 
For my DAC I'm using a Ross Martin build with a Texas Instruments PCM1794 chip. It has 2 sets of outputs (RCA and balanced) and the balanced outputs are set at 1.23 Vrms. I have no idea what the level on the RCA outs are set at but they're definitely hotter then the balanced outs.
 
I modified my Crack with a 100K 23 step attenuator so I can't be quiet as precise with the volume dial but I went LOUD just to see if it was the cans distorting. At a little past 12 o'clock there is definitely a slight bit of distortion on the kick's attack, but where you can really hear distortion is at 12 seconds in when the cymbal hits really loud. However, after the 16 second intro the kick and cymbals are as clean as can be.
 
Just for kicks I used a different DAC too - my little Aune T1 and heard the same distortion, although not quite as clearly because it's definitely not as revealing as the Ross Martin.
 
Also forgot to mention, the version I have of the album is the Qobuz Studio Master in 24/88.2 FLAC.
 
Feb 14, 2014 at 11:19 PM Post #1,714 of 4,487
Ok, I did some looking around at 6SN7 vs 12AU7 datasheets. I have a question for you. If you were to listen at a lower sound level than your customary setting, say 11:00 o'clock, does does the cymbal hit still sound distorted at 12 seconds? How about 10:00 o'clock? If you still hear the distortion then it is due to the internal clipping of the wavefile as noted in the screen shots. If the perceived distortion goes away then there is something distorting downstream. But given the gains I've seen on the datasheets and your description of the Ross Martin unbalanced output, you may be listening VERY LOUD.
 
Feb 14, 2014 at 11:41 PM Post #1,715 of 4,487
Yeah at my normal listening volume (8-9 o'clock) it's much less noticeable but still there so it's most likely the recording. I did have the amp cranked crazy loud too for a few seconds while I was testing. 12 o'clock is obnoxiously loud and listening at that level for more than a few minutes would be bad news.
 
Feb 16, 2014 at 5:31 AM Post #1,717 of 4,487
This is the a very detail headphone with very bright highs. I believe that it is much better than the hd700 which is not as neutral and detail. Such headphone should be highly praised and the price of this is very reasonable. Beyerdynamic can well sell this for over a thousand dollars with competitors such as the LCD 2. This headphone is consider a bargain when you compare to the others.
 
Feb 17, 2014 at 10:14 AM Post #1,718 of 4,487
I want to run the T90's with a Crack amp, but got no idea which DAC is suitable for it. I hear these headphones are very sensitive about the equipment that's used to run them, so I want to get the right one. Would a Schiit Modi cut it, maybe something in that price range?
 
Feb 17, 2014 at 10:19 AM Post #1,719 of 4,487
The Modi is good for the price; Bifrost is better, and uber Bifrost even more. With the T90 and Crack, you'll find that there's quite a bit of 'headroom' - allowing you to hear the difference with a better DAC. With DAC's do your research and get the best you can afford. If/when you upgrade your DAC later, your T90 will likely present even more detail.
 
Feb 17, 2014 at 1:31 PM Post #1,721 of 4,487
jamesng45678 said:
  This is the a very detail headphone with very bright highs. I believe that it is much better than the hd700 which is not as neutral and detail. Such headphone should be highly praised and the price of this is very reasonable. Beyerdynamic can well sell this for over a thousand dollars with competitors such as the LCD 2. This headphone is consider a bargain when you compare to the others.
Click to expand...

 
I've never heard the LCD2. You think it's roughly comparable?
 
Feb 17, 2014 at 3:07 PM Post #1,724 of 4,487
Ooh. I want to buy more headphones all of a sudden.
 
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