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published: Jan-24-2016

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NO SMOOTHING is applied to the shown plots. Most measurement sites have some smoothing applied which ‘irons flat’ sharp peaks and ‘wiggles’. I do not use smoothing because some info about sound quality is lost when plots are smoothed.

Aside from a small correction of the microphone itself also some correction in the lowest frequencies is applied to the plots to compensate for the perceived loss of bass when using headphones. This is described HERE in more detail.
A ‘horizontal‘ frequency response curve on the shown frequency response plots on this website thus indicates a perceived ‘flat’ tonal signature.

ALL measurements are made with a good SEAL on a flatbed measurement rig.
shape of your head, bone structure, pad size, pad ‘softness,  (compliance), hair or no hair and or wearing glasses may (drastically) change the frequency response of some headphones, so… your personal experience may differ substantially from these plots.

Frequency response (tonal balance) is the most sound-determining aspect of headphones. A horizontal line shows audible neutral response in the plots on this website. Deviations in different severities at different frequency bands have an effect on the sound character.
The bigger the deviation the stronger the effect.

Below an aid to help determining the sound character of headphones with relation to the frequency response.


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Ausdom M05


The Ausdom M05 is a rather cheap (around $60.-) bluetooth headphone of above average build quality in this price range. It appears to be well made and has a luxurious appearance.
The bluetooth part works well. It can also be connected to a normal headphone jack (3.5mm TRRS) via a thin cable that comes with it. The tests below are all made using this cable. Performance of the bluetooth connection may differ somewhat in sound quality (did not test this).
When the bluetooth part isn’t used or the battery is empty the headphone can still be used with the 3.5mm TRRS jack which is a good feature.

The sound signature is quite a bit on the ‘dark side’. On top of this it sounded quite ‘cuppy/honky”.
Real deep bass was lacking and the bass image shifted from left to right when positioning the headphone or moving around.
This was caused by the seal issue mentioned in THIS modfication guide.
Below a frequency plot that clearly shows what happens even when the seal is just slightly broken (much less than the pictures above).

seal broken-b

Stock M05 with perfect seal, stock M05 with seal slightly broken.
The bass is lowered and a 10dB peak around 600Hz makes the sound thin and ‘hollow/cuppy’.
When you get a
good seal the stereo image was correct.
There were lows but not well defined. Also it did not do deep subbass rumbles very well.

The mids still sounded ‘cuppy’. A bit like the singers were singing into a large plastic cup.
Treble was there … and smooth but much too subdued, just like the clarity is.

I can imagine young folks playing low quality streamed pop music may even like the stock sound.Bassy, subdued highs and no ‘harshness’.

Below the frequency response of the stock M05 (left, right)

FR M05

Way too much lows and above all lower mids. These cannot be called hi-fi headphones.
Some small channel imbalance, nothing to worry about in this price class.

Below the CSD of this headphone (Left and Right superimposed)


Everything above 2kHz isn’t all that bad, no dealbreaking resonances or too jagged response. Below 2kHz … it’s a bit messy and resonating.

Below the distortion plots of the  right channel (below).

DIST stock M05
These modifications aren’t very difficult to do but do ask some soldering and modification experience though.

Once modified the headphone becomes MUCH better sounding without any of the ‘cuppy’ sound and ‘muddy’ lows.

The difference between the stock and the modified headphone is shown below.

modified vs stock M05 (R)

The warm and bassy character has remained, the cuppy sound is gone and the tonal balance is MUCH better.

below the frequency response of the modified version (left, right)

FR modified M05

CSD of the modified M05 (left, right superimposed)

CSD modified M05

Quite an improvement below 2kHz.

Distortion also is greatly reduced as can be seen in the plot below. (right channel)
When this is compared to the stock version (see above) it is obvious the distortion between 100Hz and 1kHz got much less as well.

DIST modified R

Below the squarewave and impulse response plots of the stcok M05 on the left side and the modified version on the right side.

ausdom SQR

The square-wave response plots show substantial improvements, The impulse response also became much, much better.

The sound of the modified version is much improved and once a good seal is obtained (not easy) the sound is actually quite good, A smooth and still somewhat warm sound without any sibilance or harshness to it.

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