Topping L50 Headamp Review and Measurements: Another One Bites The Dust

20-ohms maybe from -10 to -30dBu as I see reasonable. The super lower impedance headphones seem to be more sensitive.

Anyway will take measurements of this with what I'm currently doing with the distortion surfaces at 29-ohms (and high-gain) for now.

 

With a 100k load (basically nothing), the voltage high-gain of the L50 is almost x5, which translates into 14db. I left this as is because I wanted to give the L50 the benefit of the doubt with the L and R channel disparity. It happens. Stuff happens. I unplugged everything and plugged everything back in. Even redid the same 29-ohm high-gain measurements with the Pietus amp and a new set with the Magni Unity.

This is 0dBu into 29-ohms. Not as punishing as the 26.4-ohm load at 8.23dBu or 2Vrms.


There's still a disparity between the two channels.

Since the gain of the high-gain setting is similar to that of the other amps I've measured recently, I will go about with distortion surface measurements anyway using a 29-ohm load with 90kHz bandwidth to keep things apples-to-apples.

 

Topping L50 Headphone Amplifier

• HIGH-GAIN
• 29-ohm load
• 90kHz bandwidth
• APx555 "cheat" HPSA mode on
• Volume knob of headphone amp was set for unity gain
• Gen level to amp inputs set on the APx555 to arrive at desired output from amp
• APx555 "cheat" HPSA mode on

H2


H3


H4-10


This is with the R channel that performed worse, The distortion starts to rise a higher output levels with H2 starting to rise earlier than H3. Still, the results are still utterly fantastic! Note how low the third harmonic is that it goes below the graph floor! Distortion is even from lows to highs.

I can't take anything away from Topping. Kudos to Topping from a measurement perspective!

Notes:
H2, H3, and H4+ above do not include noise
H2 and H3 tend to be dominant over the higher orders, additional graphs will be added if this is not the case
H2 and H3 do sound different from each other, as to how, that's another discussion
H4+, the higher order distortions can be considered to be "crap" factor
There is thought that higher order distortion may have an outsized negative affect on sound quality
THD+N does include the noise component as well as THD (sum of H2, H3, and H4 and above)
Distortion is signal that is not supposed to be there
H2 or second order at 100Hz means there is a signal at 200Hz that is not supposed to be there
H3 or third order at 100Hz means there is a signal at 300Hz that is not supposed to be there
This graphs tells us how loud the distortion is at that harmonic
Distortion that lands in the ultrasonic region matters, if SOTA chip companies like TI care, then so should you.
0dBu (0.775Vrms) output level on most headphones will cause hearing damage after a few minutes of exposure
0dBu output level may burn out the voice coil on sensitive headphones with extended use

 

THD (no noise component)


THD+N


Excellent. Again, this is from the less perfect R channel, otherwise we would continue to see THD go down with increasing output instead of leveling off.