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DT880 600ohm BS - Page 10  

post #136 of 352
Quote:
Originally Posted by chinesekiwi View Post

However of course the problem of digital attenuation is that the noise level stays the same. There's an article from an electronic engineering magazine that goes into this and why analog is preferred sound quality wise that I'll find later.

 

 

 

you should want the noise level to stay the same - inaudible

 

 

good analog, good digital can be source limited

 

bad analog and bad digital do exist but the best of either can exceed the requirements of normal music listening 

 

 

people strongly complained about "breathing" noise modulation in dynamic range companders working in the analog domain, tape hiss is often heard in digital remasters

 

50-100 KOhm volume pots can introduce white noise above that of most active electronics - with peak added noise at 6dB attenuation, decreasing as you turn volume up or down from that point

 

most real musical event recordings will have room and microphone noise well above that of properly gain structured playback electronics

 

 

today the majority of recordings are mixed, mastered in the digital domain which involves digital gain/attenuation of every mic feed


Edited by jcx - 9/7/10 at 7:45am
post #137 of 352

"today the majority of recordings are mixed, mastered in the digital domain which involves digital gain/attenuation of every mic feed"

 

In 32 bit float that is so I don't think that's a problem.

post #138 of 352

as I mentioned above expanding compressed audio formats results in more than 16 bit output - any standard core dsp processor used for DAP is going to be at least byte oriented so 24 bit internal representation would be the minimum with 32 probably the default if you're using Arm or similar

 

some players accept 24 bit resolution audio files - any further processing like eq requires extended wordlength too - I think its safe to assume most DAP do have >16 bit internal resolution

 

early DAP used 24 bit DAC - when we could still identify the part before custom chips became the norm - again it seems likely many manufacturer's would just tweak the existing 24 bit DAC IP for the custom DAP DACs 

 

I really don't think "good" digital volume control is beyond current DAP technology - the "bit loss" criticism should be a dead issue

post #139 of 352
Thread Starter 


 

Quote:
Originally Posted by nikongod View Post

whats with updating the whole OP?

 

No joke its uncool.

 

Threads are not tech-papers, they are conversations. It is supremely uncool to edit info out of old posts even if to add new info elsewhere. 

 


Err..um.  Are you supposed to be the consultant of that which is or isn't cool?  I don't propose to be cool, and thus I don't abide by the traditional cool rules. 

 

It's my thread, and I felt that a summary of the contributions would be useful to first time viewers, rather than stick a synopsis on the 8th page.  I'm sure many head-fiers appreciate a summary of all of the postings.


Edited by Catharsis - 9/7/10 at 3:45pm
post #140 of 352
Quote:
Originally Posted by Catharsis View Post

 Are you supposed to be the consultant of that which is or isn't cool? 


It may be your thread, but get over it.   nikongod is the god of cool!  

 

USG

post #141 of 352
Thread Starter 
Quote:
Originally Posted by upstateguy View Post




It may be your thread, but get over it.   nikongod is the god of cool!  

 

USG

 

I thought he was the god of nikon, and coolgod was the god of cool.  My mistake.....
 

post #142 of 352
Quote:
Originally Posted by Catharsis View Post



 

I thought he was the god of nikon, and coolgod was the god of cool.  My mistake.....
 


LOL,  it is confusing, isn't it?

post #143 of 352

I appreciate you started this thread catharsis, good infos.

post #144 of 352

Beyerdynamic USA was kind to send me a set of DT880 600 ohm to measure and compare against my 250 ohm set. I measured both using my B&K microphone in a simple fixture which holds the earcups apart approximately the same distance as the width of the average human head. I powered them from a hi-fi power amp with near 0 ohm output impedance. I then added a 100 ohm resistor in series to see how this affects the frequency response.

 

First, here's the comparison coming straight from the power amp with near 0 ohm source impedance. The dotted yellow curve is 250 ohm; solid green is 600 ohm. This is a relative measurement - not absolute SPL. The 250 ohm version has greater voltage sensitivity, so I offset the 250 ohm's curve to match the midrange SPL of the 600 ohm curve. Notice the curves are very similar but differ by a few dB in the treble.

 

DT880 comparison 0 ohm source.tif

 

 

I then measured them with 100 ohm resistor added in series. Again, the dotted yellow curve is 250 ohm; solid green is 600 ohm.This is a relative measurement - not absolute SPL. I offset the 250 ohm's curve to match the midrange SPL of the 600 ohm curve. Besides the difference in treble, notice the divergence now in the bass with the 250 ohm version having more energy in 40-50Hz range. It's difficult to measure low frequency SPL accurately due to ambient environmental noise, but there was consistently a difference.

 

DT880 comparison 100 ohm source.tif

post #145 of 352

Thank you very much for the actual data!

 

I wish I had the stuff sitting around to do this kind of thing myself

post #146 of 352


 

Quote:
Originally Posted by Donald North View Post

Beyerdynamic USA was kind to send me a set of DT880 600 ohm to measure and compare against my 250 ohm set. I measured both using my B&K microphone in a simple fixture which holds the earcups apart approximately the same distance as the width of the average human head. I powered them from a hi-fi power amp with near 0 ohm output impedance. I then added a 100 ohm resistor in series to see how this affects the frequency response.

 

First, here's the comparison coming straight from the power amp with near 0 ohm source impedance. The dotted yellow curve is 250 ohm; solid green is 600 ohm. This is a relative measurement - not absolute SPL. The 250 ohm version has greater voltage sensitivity, so I offset the 250 ohm's curve to match the midrange SPL of the 600 ohm curve. Notice the curves are very similar but differ by a few dB in the treble.

 

 

 

I then measured them with 100 ohm resistor added in series. Again, the dotted yellow curve is 250 ohm; solid green is 600 ohm.This is a relative measurement - not absolute SPL. I offset the 250 ohm's curve to match the midrange SPL of the 600 ohm curve. Besides the difference in treble, notice the divergence now in the bass with the 250 ohm version having more energy in 40-50Hz range. It's difficult to measure low frequency SPL accurately due to ambient environmental noise, but there was consistently a difference.

 


Interesting data.

 

Just a few of questions-

 

-  what are your conclusions?

 

-  are the differences in the plots audible? 

 

-  is adding a 100 ohm resistor to an amp that is designed to have an output impedance of 0 ohms, sonically the same as an amp that is designed to  have an output impedance of 100 ohms?

 

USG

post #147 of 352

@ Donald

 

Couldn't the minor differences in treble from the first graph be more an issue with tolerances and yield than an actual distinct difference caused by the impedances?

post #148 of 352
Quote:
Originally Posted by upstateguy View Post


 


Interesting data.

 

Just a few of questions-

 

-  what are your conclusions?

 

-  are the differences in the plots audible? 

 

-  is adding a 100 ohm resistor to an amp that is designed to have an output impedance of 0 ohms, sonically the same as an amp that is designed to  have an output impedance of 100 ohms?

 

USG



Yes, as I have mentioned in previous posts the 2 versions of the headphone do sound different. To me, the 250 ohm versions sounds like it has more vocal presence and cymbal energy when playing rock. I also hear more bass from the 250 ohm version when powered by an amplifier with 100-120 ohm output impedance and prefer this tonal balance - it sounds more even to me.

 

From these measurements it's not obvious to me that one model is superior to the other. In my opinion it comes down to personal taste - go with the one you prefer.

 

A 0 ohm output impedance amplifier with 100 ohm resistor added on the output should perform theoretically the same as an amp designed with 100 ohm output impedance. However to achieve this in practice may require different circuit topologies which may yield slight sonic differences. I personally don't own 2 such amplifiers to comment.
 

Quote:
Originally Posted by Shike View Post

@ Donald

 

Couldn't the minor differences in treble from the first graph be more an issue with tolerances and yield than an actual distinct difference caused by the impedances?


The difference in treble ranges from 2.5 - 5dB which is significant and in my opinion is not due to manufacturing tolerances. I tested the 2 versions before using the same 250 ohm set and a different 600 ohm set and the treble difference was still there. If they were closer, like 1dB, then one could argue it's due to manufacturing tolerances.

post #149 of 352

Can you make some graphs of each headphone separately with and without the resistor?

 

I would also be interested in seeing data using an amp with a higher output impedance, as that would (I think?) have a noticeable affect on damping factor, although I'm not sure if that would show up on an SPL graph.

post #150 of 352
Quote:
Originally Posted by Donald North View Post
A 0 ohm output impedance amplifier with 100 ohm resistor added on the output should perform theoretically the same as an amp designed with 100 ohm output impedance. However to achieve this in practice may require different circuit topologies which may yield slight sonic differences. I personally don't own 2 such amplifiers to comment.

 


Really? I thought it would add a virtual 100 ohm load to the headphones.

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