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OLLO S5X Headphone Review

Rate this headphone:

  • 1. Poor (headless panther)

    Votes: 32 25.2%
  • 2. Not terrible (postman panther)

    Votes: 59 46.5%
  • 3. Fine (happy panther)

    Votes: 25 19.7%
  • 4. Great (golfing panther)

    Votes: 11 8.7%

  • Total voters
    127

amirm

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This is a review, listening test and measurements of the OLLO Audio S5X open back headphone. It is on kind loan from a member and costs US $449.
Ollo Audio S5X headphone semi open back headphone review.jpg

The S5X looks nice and differentiated. Comfort was very good. Alas, the sample I received had a pretty crushed left cup (on top) which made it harder to get matching channel response. Company advertises it as: "Reference class, open back, dynamic headphones with flat frequency response for binaural/immersive mixing made in the EU." Let's see if it does that.

Ollo S5X Measurements
We start with our usual frequency response measurement:
Ollo Audio S5X headphone frequency response measurement.png

Response is kind of flat but something is causing that opposing kink between 200 and 300 Hz. For our use which is enjoyment of music, it likely is deficient in both bass and lower treble which images spatial qualities. High frequency seems to comply with our target with all the peaks reaching the target.

Relative response to our target shows a complex shape:
Ollo Audio S5X headphone relative frequency response measurement.png

It will be interesting to see if I can develop a set of filters for it to flatten that curve.

When it comes to distortion, that kink in frequency response manifests itself in a lot of impairment:
Ollo Audio S5X headphone relative THD distortion measurement.png

Ollo Audio S5X headphone THD distortion measurement.png

It seems that the industry is so focused on frequency response that such simple distortion measurements are not performed to catch what is clearly a flaw.

It is so bad that even our group delay shows it:
Ollo Audio S5X headphone group delay measurement.png

And even impedance measurement!
Ollo Audio S5X headphone Impedance measurement.png


Sensitive is better than average though so it should be an easy drive for most sources:
Most Sensitive efficient headphone review 2023.png


OLLO Audio S5X Headphone Listening Tests and Equalization
First impression was a sound that was inoffensive and not exciting. So I decided to apply EQ:
Ollo Audio S5X headphone semi open back reference headphone equalization.png


It took some trial and error to optimize the highest frequency filter. I was amazed how much difference that filter at 213 Hz made. I think the harmonics of that distortion were polluting the spectrum above above.

With all of these filters in place, the sound was delightful courtesy of angled drivers that provided neat spatial effects. There was plenty of bass and the sound was much more open due to higher frequency boosts.

Conclusions
The S5X has a clear flaw in upper bass area which manifests itself in a lot of distortion. Its frequency response is as claimed ("flat") but that is not what we like as audiophiles. Fortunately it is fairly fixable in EQ and as is typical, transforms the experience in a dramatic way. You can now sit back and really enjoy your music. At the same time, if you have to use it without EQ in some other secondary situations, the sound is not bad.

I can't recommend the OLLO Audio S5X as is. With EQ it gets much better.

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As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
 
I have to say tough, It is quite rare to see a dynamic drivers open back with bass extension all the way to 20 Hz with no real significant roll off and while still maintaining distortion in check in the 20-60 Hz area. Just for that it's interesting in term of driver advancement. That 300 Hz Oddity is a concern tough.
 
index.php


For some reason the frequency response looks closer to what I measured with felt mod. (stock)
red-stock-s5x-teal-1mm-felt.png

Note that my preference nor target is Harman in the bass. While impressive I belong to the 25% that desires a few dB less bass elevation.

Below stock.
fr-s5x.png

No smoothing applied.

Note the wiggle right channel only at 250Hz, left at 300Hz.
The light 'bump' in the lower mids gives the sound some 'body/warmth'.
I get no distortion at 92dB (400Hz) it actually dips at that resonance frequency.
dist-90db-r-percent.png

Also I see no compression even at 100dB.

Group Delay:
gd-s5x.png

R shows a small resonance at 250Hz and L at 350Hz and a small short lived one at 3.8kHz. This is around a frequency where the ear 'resonates' as well.
csd-s5x.png


The 250/350Hz resonance also shows up in the step response.
step-s5x.png


Been using it as my main headphones (but with a small modification)
sounds very similar to a nearfield monitor which actually is its purpose. It is designed for studio usage.
I like it a lot but needs the felt (just like the DCA headphones with inserts need it not to sound too sharp).

I don't listen at high SPL and sounds distortion free and 'smooth' (with felt) to me.

I have to say tough, It is quite rare to see a dynamic drivers open back with bass extension all the way to 20 Hz with no real significant roll off and while still maintaining distortion in check in the 20-60 Hz area. Just for that it's interesting in term of driver advancement. That 300 Hz Oddity is a concern tough.

That is because this is a semi-open headphone. As such it needs a perfect seal to extend well.

seal-s5x.png


My main concern is comfort and fit.
While the headband and tilt/swivel system is improved over the S4R and S4X in order to get a good and comfortable fit I had to resort to bending the headband in strategic places otherwise it would have too little pressure on the bottom side and too much on the top side due to the too small 'tilt' range of the cup design.
 
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Ollo makes this statement in their marketing materials:

The ex-centric and angled speaker in a conical radiation chassis with an optimal sound stage for the spatialization of objects in the binaural renderer.

Is this just marketing speak to take advantage of the current Atmos/Spatial craze, or is there actually something to this?
 
The angle is just 6° and IMO does not do much.
driver-front-s5x.jpg

The slight offset driver reminds me of a tiny bit of 'Ultrasone' ideas.
Ultrasone+Pro+550+Headphones+Audio+Drivers.jpg
[
Note: the lack of rear porting, this is responsible for the bass extension. On the right side a necessary pressure equalization hole (covered with acoustic paper).

I get no 'HD800' spatialization. The dip around 3kHz can give some people the impression of a bit more depth.
Spatial effects on binaural (and regular music) do nothing special for me. Admittedly binaural doesn't work for me, not even with HD800. My brain does not seem to be wired for that but weirdly enough do get a very good 3D image using (electrostatic) speakers using regular well made recordings.
 
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The angle is just 6° and IMO does not do much.
driver-front-s5x.jpg

The slight offset driver reminds me of a tiny bit of 'Ultrasone' ideas.
Ultrasone+Pro+550+Headphones+Audio+Drivers.jpg
[
Note: the lack of rear porting, this is responsible for the bass extension. On the right side a necessary pressure equalization hole (covered with acoustic paper).

I get no 'HD800' spatialization. The dip around 3kHz can give some people the impression of a bit more depth.
Spatial effects on binaural (and regular music) do nothing special for me. Admittedly binaural doesn't work for me, not even with HD800. My brain does not seem to be wired for that but weirdly enough do get a very good 3D image using (electrostatic) speakers using regular well made recordings.
That’s awesome, thanks for the photos and information.

I finally broke down and did some Atmos mixes using headphones in Logic. To get an accurate take on what was happening I had to use Apple headphones, my HD800S didn’t work very well. I thought perhaps the Ollo would be better, but it doesn’t appear that way.
 
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After the DCA AEON 2 Noire another headphone I wished measured better. It looks like an interesting company and heaphone, though. Yet the distortion level and especially that 230 Hz peak are pretty concerning
Yes, but solderdude unit don't have that 230 Hz distortion spike. Maybe Amir got a defective units, especially with the mention "the sample I received had a pretty crushed left cup (on top)" Not sure what that mean, I don't see that in the picture.
 
Would we use another target for studio/mixing use ?.
I don't have a definitive answer for you. I do know that a speaker in a room generates far warmer bass response than a headphone with flat response.

One of the neat things about headphones is that to go way down in frequency, down to 10 Hz and even lower! Use flat response though and almost all of that goes to waste. Boost it per Harman curve and it comes alive, beating any speaker I have heard in how clean and deep the bass becomes! You won't feel it in your gut but what plays in the ear is incredible.
 
I have to say tough, It is quite rare to see a dynamic drivers open back with bass extension all the way to 20 Hz with no real significant roll off and while still maintaining distortion in check in the 20-60 Hz area. Just for that it's interesting in term of driver advancement. That 300 Hz Oddity is a concern tough.
That was my thought as well. Let's keep this company on our radar. It seems that this project is a few tweaks from being great.
 
One of the neat things about headphones is that to go way down in frequency, down to 10 Hz and even lower! Use flat response though and almost all of that goes to waste. Boost it per Harman curve and it comes alive, beating any speaker I have heard in how clean and deep the bass becomes! You won't feel it in your gut but what plays in the ear is incredible.
I have the same feeling.
The (usually) much lower distortion of headphones are also of great benefit.

What you need for mixing is a balanced FR, similar to an ideal speaker (although it's known to be risky to rely solely on headphones for mixing).

(Of course, it's also a matter of habit. Some mixers, I've heard, are used to studio monitors "zooming", as an example, on mids. But they know how to deal with that.)

Given your sentence in the review, I just wanted to check if there is any different/specific theory behind this.
 
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The audio production and reproduction transducers should have the same perceived response in order to avoid the circle of confusion. See Dr Sean Olive's article here:
 
The audio production and reproduction transducers should have the same perceived response in order to avoid the circle of confusion. See Dr Sean Olive's post here:
Exactly.
Thanks for the quote.
 
I've been using them for more than 3 months now and I really appreciate them. The first headphone since HE-4xx that don't kill my ears with exagerrated highs. Also tried Avantone Planar before S5X. I loved the sound but it was way too heavy on my head.

I wonder about this high distortion issue, perhaps it's indeed a defective unit.
 
Thanks for the review.

Would we use another target for studio/mixing use ?.
Sonarworks is pretty much ubiquitous for headphone correction in studios. Their target is similar to Harman but with a bass shelf that starts roughly 1-1.5 octaves lower.
 
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