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# FR graphs - neutral, yet below 0 dB?

Alright, so lets say one headphone has a frequency response graph that shows a generally neutral tone while generally being close to 0. (lets say MDR-V6)

And another headphone has a much flatter frequency response, BUT the line is below 0 for the part where its flat. (lets say RE-272).

Now going purely by the graphs, which would be considered more neutral? This is something that has been digging at my brain for a while now. I mean one headphone isn't as flat, yet is closer to reference, but the other is flatter but at a further distance from reference.

Any help is appreciated. Thanks.

Just thought of adding these two datasheets from Innerfidelity to better explain my question:

http://www.innerfidelity.com/images/SonyMDRV6.pdf

http://www.innerfidelity.com/images/HiFiMANRE272.pdf

You're interested in the shape (flatness), not where it's placed in terms of vertical position on the graph.  Shift the entire curve up or down in your head if it makes you feel better.

Actually, I have no idea how he's placing those plots.  I've seen others normalize all their graphs so the reference point of 0 dB is always the level at 1 kHz, but I don't see any convention to what's at InnerFidelity. Maybe I'm missing something?

But isn't it true that the further above/below reference the line is the more over/underemphasized a particular frequency is?

Quote:
Originally Posted by Siva108

But isn't it true that the further above/below reference the line is the more over/underemphasized a particular frequency is?

Yes but the zero on the y-axis is arbitrary, one simply has to turn up the signal amplitude to move the curve up.

The exact shape however will likely change slightly (and drastically as you approach the SPL limits, I would expect). Having a convention of providing sufficient input power for a response of x dB (or pascals, whatever) at y Hz would be a good idea.

Edited by joeyjojo - 8/6/12 at 7:05am

I'm sorry mate, could you please put that in layman's terms?

What I understood from that is that the further below 0 a FR is, the more it will benefit from amping? Is that right?

To put it simply, the vertical positioning of the curve as a whole has no importance whatsoever, what matters is simply how range x compares to range y in the graph, it's ALL ABOUT THE BALANCE of the amplitudes of the frequencies AGAINST each other in the same graph only, not if headphone A has the amplitude something vs headphone B which has another amplitude at the given frequency range. To understand what's concidered recessed or emphasized in a headphone's graph you need to introduce an "average frequency amplitude" for the graphs which is simply the average amplitude value which I'll show an example of in a few mins in the given FR graphs you posted above.

Edited by RPGWiZaRD - 8/6/12 at 7:42am

Thanks man. :)

So how would one go about comparing FR of different headphones then?

Btw, wouldn't this make IEMs like most Etys and the Re272 and the like utterly destroy pretty much every full size headphone available in terms of neutrality?

Edit: Just saw your edit, awaiting eagerly. :D

Edited by Siva108 - 8/6/12 at 7:53am

Limegreen line represents the "average frequency amplitude". I don't find any use of taking into account below 20Hz and above 20kHz as it may just skew the results, especially for open headphones which usually lack bass extension versus closed.

On V6 it has probably among the most flat measuring headphones I've seen with the most neutral "tonality" I've seen, probably why it's found in so many recording studios. Due to the slight dip after 50Hz as well as around 6kHz area (but should be mentioned Tyll's measurement almost always shows a dip in this area so it may just be something limited to this specific equipment/test procedure of his and might even be quite straight in reality which is my guess due to almost all headphones showing this dip) the line should be drawn slightly under the rather straight FR plot in the 50 - 5kHz or so range. Well if you want to be extremely picky you could perhaps make the line possibly ever so slightly upwards tilting due to the bass extension roll-off and 9~10kHz spike but that would be such a small tilted angle I just preferred drawing it straight in this case. Anyway it looks like there's like ever so slight emphasis around midrange and even smaller so in the 50-150Hz or so range but from my experience a 3dB variety in the FR graph isn't really going to stand out and will still sound pretty flat to our ears, might be more closer to 5dB or so variances when it becomes noticable, the peak at 9~10kHz is probably slightly noticable. Anyway this is probably the most flat measuring headphone in its price class by far, with only a slight roll-off below 50Hz and above 10kHz (I'm not convinced enough about Tyll's 6kHz dip as it's so frequently showing up and I've seen some other plots where it wasn't the case either so)

HE272 then again has a slight warm tilt in tonality (line is tilting forwards) versus the V6 with a more significant midrange spike in-between the 1000 - 2500 Hz range which is most likely audible for a more experienced ear probably with certain female vocals for example. It also has a relatively similar spike around 9kHz as V6 (well most headphones have a slight emphasis in this area and this is more the norm than an exception and a 5dB spike here isn't anything unusual at all). But yea it's fairly flat in the bass range overall and has an emphasis in the 1000 - 2500Hz range and recessed/rolled-off slightly around 2500 - 8kHz range and above 10kHz.

Edited by RPGWiZaRD - 8/6/12 at 8:29am

Thanks a lot my friend.

Can you please explain how you determined the average frequency amplitude in the graphs? This is really confusing me.

Oh and just to see if I get how to read these charts, am I right in thinking the Shure SRH440s (http://www.innerfidelity.com/images/ShureSRH440.pdf) are more neutral than the V6s?

Edit: Is this how to draw the average frequency amplitude line?

Edited by Siva108 - 8/6/12 at 8:53am

WOOT I tried drawing the average frequency amplitude line on the MDR-V6 graph without looking at yours and it came out the same. I GOT IT.

I really should have taken math for my final year in school lol. :p

Thanks a lot bro. You cleared all my doubts and made it so much easier to compare frequency response.

Edit: One other doubt, is there any reason why sites like Innerfidelity don't include this with the datasheets?

Edited by Siva108 - 8/6/12 at 9:40am
Quote:
Originally Posted by Siva108

WOOT I tried drawing the average frequency amplitude line on the MDR-V6 graph without looking at yours and it came out the same. I GOT IT.

I really should have taken math for my final year in school lol. :p

Thanks a lot bro. You cleared all my doubts and made it so much easier to compare frequency response.

Edit: One other doubt, is there any reason why sites like Innerfidelity don't include this with the datasheets?

Well there's no written in stone rule about this, but since FR is really about balance (you make one part more recessed and the rest of the range will automaticly get louder/more present as a result or vice versa) it makes sense to compare to an average amplitude of some sort, but unsure what's the proper way of doing it calculation wise etc, I just measure roughly with the eyes.

Oh and the starting position is probably a bit awkward on the 2nd graph for the HE272 I showed (should maybe be like 2dB lower or so) but yea at least it gives you an idea.

I'd say that's roughly it as you drew it.

Edited by RPGWiZaRD - 8/6/12 at 10:03am

One other doubt that just arose.

So once you draw this line, can you just look at how straight this line is and compare headphones? Like if one headphone has a straight line while another has a downward sloping line, the one with the straight line would be more neutral?

Or is this line simply the reference point, from where how much a particular frequency is recessed/overemphasized can be assessed?

No, there can be headphones which has FR graphs which looks like a rollercoaster and have like 10dB varieties yet the line could perfectly straight as the dips and peaks could be equally large and therefore averaging out themselves so the result is still a straight line but what I think it does is that it gives a hint of a headphone's "tonality", is it warm or bright sounding headphone. I'd say already rather straight line tend to sound relatively bright such as the V6 to most people's ears already.

downwards = warm

upwards = bright

Edited by RPGWiZaRD - 8/6/12 at 10:18am

Alright confused again. :p

Are you saying it doesn't matter if the line is downwards sloping or flat or upward sloping, it'll be neutral either way (but sound 'warm' or 'bright' depending on the angle of the line)?

But wouldn't that make every headphone out there neutral since the line will come out as straight anyway?

Thanks for the patience. :p

Edited by Siva108 - 8/6/12 at 10:55am
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