Using my Topping D10B as a headphone amp!!!

[fatoldgit]

Couldnt be shagged buggering around with the power plugs in my office to setup a "full stack" headphone amp on my desk so plugged in my spare D10B running this puppy.

I use Linux in my office (in fact everywhere) and was surprised that the pulseaudio volume control wasnt in the path (it is when outputting to the headphone output on my motherboard) meaning the D10B was at full output (even after trying the various available D10B sinks)

But as I have sox in my pipeline doing upsampling (with normalization), I just changed the normalization attenuation from -4 to -20 (after a bit of testing) and bingo, a nice level.

Sounds fine driving HD650's... wasnt sure if headphone amps have any special secret sauce (aside from volume and source selection) so at least in this case, doesnt seem so.


Peter

 

[Veri]

Sounds fine driving HD650's... wasnt sure if headphone amps have any special secret sauce (aside from volume and source selection) so at least in this case, doesnt seem so.

Well actually you are using line level amplification to drive a headphone load. DAC output can be easily 100Ω or much more, while a headphone amp should have near 0Ω output impedance which can heavily impact the sound. Also, depending on what you're driving you might be clipping the poor little DAC output.

So no it's a pretty bad idea. Sure it might work with some headphone you're testing, but the point of a headphone amp is to have a reliable output to use with headphones, earphones/IEMS, planar magnetics alike. So be wary of what you're doing.

 

[fatoldgit]

Well actually you are using line level amplification to drive a headphone load. DAC output can be easily 100Ω or much more, while a headphone amp should have near 0Ω output impedance which can heavily impact the sound. Also, depending on what you're driving you might be clipping the poor little DAC output.

So no it's a pretty bad idea. Sure it might work with some headphone you're testing, but the point of a headphone amp is to have a reliable output to use with headphones, earphones/IEMS, planar magnetics alike. So be wary of what you're doing.

agree and I was surprised.

With the amount of attenuation I am using I dont think I will overtax the DAC and after a couple of hours listening to my suite of test tracks that I use for subjective evaluations I cant hear any thing amiss.

My music tastes (Blues and Jazz) means I dont venture into bass heavy music which I am sure a real headphone amp would be expected to handle. Plus I am not listening at loud levels.

As I say, I expected this little experiment to end in tears but so far so good.

Peter

 

[staticV3]

Not only are you overloading the Line output with a load it's not designed for, you're also shorting out L- and R- which depending on your music could lead to permanent damage of the DAC's output.
Please don't do this.

If you want a simple, small, All-in-one DAC+Headphone Amp, take a look at the DX1.

 

[Veri]

Not only are you overloading the Line output with a load it's not designed for, you're also shorting out L- and R- which depending on your music could lead to permanent damage of the DAC's output.
Please don't do this.

If you want a simple, small, All-in-one DAC+Headphone Amp, take a look at the DX1.

Oh yes good point, I thought it was the D10s not the D10b.

 

[fatoldgit]

Not only are you overloading the Line output with a load it's not designed for, you're also shorting out L- and R- which depending on your music could lead to permanent damage

In my defense, Your Honour, I present the following facts:

1- The DB10B has a stated max output of 4.2Vrms@0dBFS
2- The HD650 has a "Tested By Amir" impedance curve of 320 (20HZ) to 480 (20khz)
3- The DB10B has a stated output impedance of 88
4- My music is attenuated by 20DB (-20db)

This means:

1- even if I have some music that hits 0dBFS(extremely rare... I have checked all 5000 albums for such events), that peak will in fact register -20dBFS
2- My math tells me (correct my if I am wrong) that 4.2V@0dBFS is something less than 0.4V due to my attenuation
3- Thus, even in the worst case of hitting 0dBFS (but relative to my -20db attenuation) , I still have ~3.8V of unused headroom (i.e. I am not taxing the opamps at all)
4- While the output to input impedance of ~4X is not ideal (when compared to what the DB10B would see when compared to a pre-amp), it is impossible for to invert (i.e. go bad)
5- Yes the opamps are dealing with a reactive load in the form of the HD650's but again the opamps are never being stressed due to the level of attenuation involved
6- With regard to shorting (which is a legitmate concern), again I think that the lack of stress the opamps are under effectively negates this as a concern
7- If it all turns to custard, It doesnt matter... I got the DB10B as a throw away item for some testing I was doing and so rather than having it sit in a box for the rest of its life, lets give it a purpose.

Peter

 

[Veri]

3- Thus, even in the worst case of hitting 0dBFS (but relative to my -20db attenuation) , I still have ~3.8V of unused headroom (i.e. I am not taxing the opamps at all)
4- While the output to input impedance of ~4X is not ideal (when compared to what the DB10B would see when compared to a pre-amp), it is impossible for to invert (i.e. go bad)
5- Yes the opamps are dealing with a reactive load in the form of the HD650's but again the opamps are never being stressed due to the level of attenuation involved
6- With regard to shorting (which is a legitmate concern), again I think that the lack of stress the opamps are under effectively negates this as a concern
7- If it all turns to custard, It doesnt matter... I got the DB10B as a throw away item for some testing I was doing and so rather than having it sit in a box for the rest of its life, lets give it a purpose.

All of those voltages will be halved though, since you are shorting two TRS plugs into a single/single-ended connecting to your headphones. Other than that, for a throwaway if it works, sure..

 

[charleski]

Archimago tested what happens if you run the D10B into a single-ended load, tying L- and R- together. SINAD drops to 84.5dB. It really is meant to be run balanced.

I think you’re getting away with it because your headphones are high impedance, I wouldn’t plug in anything that needs a lot of current.