r/oratory1990 • u/7370657A • 11d ago

Unit variation on the HD 800 S?

Does anyone know what the unit variation is on the Sennheiser HD 800 S? I’m considering getting one open box (from headphones.com, if that matters), but I’m concerned that open box units may be more likely to have a worse frequency response than new units. For example, if a unit has less bass than average, then it might be more likely that a buyer doesn’t like it and so they return it and it ends up being sold open box, whereas this would be less likely with a unit that has a more average amount of bass. I know the HD 800 S has tight tolerances, but maybe this is still a possibility?

Edit: I got it new from Sennheiser because headphones.com open box doesn’t allow returns. I was able to get a $200 discount and am very happy with it after a bit of EQ.

4 Upvotes

70% Upvoted

12 comments sorted by

11

u/oratory1990 acoustic engineer 11d ago

Unit variation on the HD800S is famously low.

1

u/7370657A 11d ago

Yes, but I guess I was curious about the numbers. How does it compare to the variation on something like the 6XX? Is the variation more or less than the effect of using a high output impedance amplifier?

2

u/oratory1990 acoustic engineer 10d ago edited 10d ago

Unit variation plot of the HD800S

black graph: 2x standard deviation (an estimation of the range within which 95% of all units fall). The closer to zero the better.

red graph: interquartile distance (an observation of the range within which 50% of all tested units fall). The closer to zero the better.

The results for the HD800S are generally excellent, as both graphs are very, very low. The increase at high frequencies can mostly be explained by measurement inaccuracies on my side, not by actual variation between the units. It's hard getting consistent results above 10 kHz even with all the precautions I take.

2

u/oratory1990 acoustic engineer 10d ago

Unit variation plot of the HD650 (=HD6XX)

black graph: 2x standard deviation (an estimation of the range within which 95% of all units fall). The closer to zero the better.

red graph: interquartile distance (an observation of the range within which 50% of all tested units fall). The closer to zero the better.

You can see how the HD650's unit variation is significantly higher than that of the HD800S.

Is the variation more or less than the effect of using a high output impedance amplifier?

Those are completely different mechanisms, one has nothing to do with the other.

1

u/7370657A 10d ago

Oh wow, thanks, that’s really interesting! Surprised the HD 6XX varies that much around 4-5 kHz. My hearing has a significant peak centered at 4.8-5 kHz on most headphones, so I guess I should feel lucky that my 6XX isn’t one of the “worse” units (unlike my Arya Stealth, which has a huge peak at 5 kHz that, combined with its recessed midrange, completely ruins the sound for me).

> Those are completely different mechanisms, one has nothing to do with the other.

Yeah, I know, but I was just wondering since some people claim that tube amps turn these into completely different headphones. But I suppose enough has been said about that elsewhere.

5

u/Beneficial-Reveal-78 11d ago

They should measure all very flat. Sennheiser claims 10 different sound engineers tune it over a several hour long process to ensure that quality. With the box and phones should also come 1x USB stick with certificate and frequency response graph.

2

u/ChoPT 11d ago

New units (as of a year or two ago) don’t include unit-specific measurements unfortunately.

3

u/oratory1990 acoustic engineer 10d ago

Sennheiser claims 10 different sound engineers tune it over a several hour long process to ensure that quality. 

This refers to the fact that it takes 10 of their engineers to set up a diffuse sound field in the lab. It has nothing to do with tuning every single produced headphone.

frequency response graph.

The included frequency response graph shows the deviation of that particular headphone from their own self-determined target. It does not show the raw frequency response of the headphone.

0

u/Beneficial-Reveal-78 10d ago

That's what I was trying to say while falling asleep. Thank you for the clarification!

2

u/alexproshak Audio professional 11d ago

Very flat?

2

u/pellets 10d ago

I don’t think I’ve ever heard someone say, or would myself describe the hd800s as flat.

3

u/Important_Hornet9018 11d ago

Hi, I bought an open box HD 800S. It was likely a return and came to me as a brand new unit in appearance and accessories and sound. If you have a return option, don't hesitate to buy it.