Equalizing loudspeakers based on anechoic measurements (community project)

[ernestcarl]

My intention is to remove the 2.5kHz part of the sound power peak at 3.2kHz without hurting the direct sound to much compared to the original tuning.
Compared to the auto EQ yes I want to lower the direct sound peak and get a slight dip at 2.5kHz since it sounds much less harsh and is more enjoyable with most speaker of such kind.
compromises.

Ah, I think I got it.

Besides all that extra fine surgical anechoic EQ, ~1 db reduction at 3.2 kHz is what you really think makes the biggest difference in reducing mid-HF "harshness" of this speaker.

Eh, color me skeptical... I mean, seriously, you got to be kidding me.


FDW 6 cycles ("Early" FR response)

It appears I didn't even bother EQing out that minuscule upper mid peak. Although, I did cut out some of the bass port resonance (~1.6 kHz) that seems to be leaking out (and just happens to be oddly emphasized) in my own nearfield in-room measurements as shown above.


Full frequency response ~vs~ "Late" FR response (20 ms trace)

 

[aarons915]

Even if the post is quite old I like to add some thoughts of the KH120. I also don't like the speaker because of its "uncomfortable" "harsch" sound. IMHO there are multiple reasons one of the main reason is the wave guide which provides to much energy in the very critical region of 2.5kHz to 3.5kHz. If you have a look at the sound power and sound power di you can clearly see the problem.

Measurements for speaker Neumann KH 120A

www.spinorama.org

This frequency band from about 1kHz to 4kHz is very important and smaller deviations are much more audible due to the much higher "resolution" of the human hearing.

A slight dip around 2.5kHz reduces and a slight peak increases the harshness respectively. But if the speaker starts to beam less at 2.5kHz there isn't much you can do even with an eq since the difference between the direct sound and the diffuse sound seems to be wrong for the human brain. IMHO the difference in tonality perception of direct sound vs. diffuse sound caused by the head related transfer functions is the main cause of the importance of this frequencies.

In addition the tweeter with its diffusor didn't sound well for younger ears. Around 15kHz the frequency response is a mess and you got many peaks and dips which shift with the angle. It is a trade of they wanted a wider beam but you have to pay with a wiggly frequencies response with some peaks and dips under some angles. You also got audible distortions which are caused by the hard membrane of the tweeter in these frequencies. For older people this shouldn't be a problem. For younger people it adds a bit of harshness.

So over all the KH120 sounds to harsh for me and is IMHO not a good speaker since it has these problems which made listening quite unpleasant.

Sorry I didn't see this until now. I know there is disagreement about these speakers not fatiguing everyone and I believe this is mostly due to different setups and how prominent the vertical reflections are in a particular setup. It won't be a problem in a near field setup but in a living room setup with short ceilings is where I think the problem occurs. You can check the horizontal directivity and see it's very well behaved but the verticals show dips around 2 and 4k which creates a peak centered around 3k that shows in the room response. I tried EQ'ing the peak, messed with the treble rolloff sliders on the back of the speaker, nothing worked so I believe it was simply the mismatch between the direct sound, sidewall reflections and vertical reflections that caused them to fatigue me. Note that I'm used to coaxials so I'm not sure if that had something to do with it but I don't think so, I've had other line source speakers and that's never happened before. Here's my in room MMM response that matches the early reflections very well:

 

[ernestcarl]

... I believe this is mostly due to different setups and how prominent the vertical reflections are in a particular setup.

One's room setup is a factor which is why I would prefer to see detailed measurements and a description of the complaining party's speakers in-room. The KH120 is primarily designed with nearfield studio monitoring applications in mind.

 

[aarons915]

One's room setup is a factor which is why I would prefer to see detailed measurements and a description of the complaining party's speakers in-room. The KH120 is primarily designed with nearfield studio monitoring applications in mind.

That's why I always say they are great studio monitors and if my issue was in fact due to vertical reflections, I realize that isn't their intended use case. There is no reason why "near field" monitors can't work for a stereo setup though, speakers are speakers and plenty of people use studio monitors for a home setup.

 

[Robbo99999]

That's why I always say they are great studio monitors and if my issue was in fact due to vertical reflections, I realize that isn't their intended use case. There is no reason why "near field" monitors can't work for a stereo setup though, speakers are speakers and plenty of people use studio monitors for a home setup.

I think studio monitors are great in a home general setup, based on my experience with JBL 308p Mkii monitors. I think they're good both nearfield & farfield. My farfield is nearly 4m. My nearfield is about 1.4m (same room / different listening positions).

 

[test1223]

@ernestcarl
You most likely have some early reflections which cause some of dips and peaks. There might be (a bigger?) or another problem if you have some kind of strong early reflections. Have you tried the eq I suggested? If yes what are your thoughts?

@aarons915
Thank you for your feedback. In the set-up I was testing there where almost no early reflections besides the floor an ceiling reflections. I couldn't find a clear peak in the in room response. I get the same feeling of harshness as you described which can't be EQed without destroying the mids. The frequency range which stands out to be the cause of the not good midrange was around 2.5kHz which I tested by swapping an eq up and down. Later I came across the sound power measurement which is atypical, since it implies harshness therefore my conclusion was that the harshness I was hearing was caused by that.

I think studio monitors are great in a home general setup, based on my experience with JBL 308p Mkii monitors. I think they're good both nearfield & farfield. My farfield is nearly 4m. My nearfield is about 1.4m (same room / different listening positions).

From my experience you have one optimal listening distance for a speaker in a room. And with all not very big speakers you don't get a good response at 3 or 4m since they provide not enough direct sound. It might sound better with a good near filed monitor compared with another small speaker but I don't think it is optimal.

 

[Robbo99999]

From my experience you have one optimal listening distance for a speaker in a room. And with all not very big speakers you don't get a good response at 3 or 4m since they provide not enough direct sound. It might sound better with a good near filed monitor compared with another small speaker but I don't think it is optimal.

For sure my 4m listening position is not optimal as it's not an equilateral triangle listening position with the speakers, but the 1.4m listening position is my optimal equilateral triangle listening position. I really do think they sound great at both distances, just you don't get the proper stereo seperation/integration at my 4m listening position because the speakers are too close together for that listening position (not equilateral triangle with listening position). I do use an Anechoic EQ (using Amir's measurements, which you can approximate anyway by just running the HF Trim Switch on the back of the speakers at -2dB), and also RoomEQ, and my RoomEQ is different for both listening positions of course. No, but I have zero complaints re the their abilities at 1.4m and also 4m. I think studio monitors make great home hifi speakers, but this might well be dependant on choosing one that has good horizontal and reasonable vertical directivity......in which my 308p excels re good directivity as proven by Amir's measurements, very good wave guide. They sound very consistent throughout the room.

(JBL 308p Mkii that I have are the largest of the 300 series, 8" woofer).

 

[ernestcarl]

@ernestcarl
You most likely have some early reflections which cause some of dips and peaks. There might be (a bigger?) or another problem if you have some kind of strong early reflections. Have you tried the eq I suggested? If yes what are your thoughts?

Just about every desk setup suffers from reflections and modal issues. What (unaddressed) problem are you concerned about?

With regards to your posted EQ, no, I have not tried it yet. Although, of that set, a 1dB 3.2 kHz reduction perhaps could work in terms of adding to what EQ I already have currently active -- but, I don't have the energy to A/B such small changes right now. Hmmmn... I think, quite realistically, I do not have any big expectation that it will reduce "harshness" in the way you think it will at my nearfield MLP. Because, well, my ears aren't hurting from excessive harshness or anything like that...

 

[Bugal1998]

I've been trying to track down and eliminate a bit of upper midrange harshness in certain tracks. It's a new development in my recently completed and more lively room which I never used to experience with the same JBL M2s in my prior over damped space.

The approach I used to resolve the issue was to turn-off first reflection compensation in the Trinnov Optimizer settings and set the in-room target curve to the Harman preference curve (see post 165 by @Maiky76). Using anechoic data from Erin's Audio Corner I added 0.5db to the target curve where the speaker dispersion is slightly narrower than average (800-1200hz) and ramping up starting around 8500hz added 2db-2.5db extra by 20khz where dispersion has significantly narrowed. Most impactfully, the target curve was reduced by 1-1.5db where the dispersion is wider than average (1500-4000hz).

Speakers are toed in ~10° from straight ahead, and positioned approximately 55° apart.

It's all subtle, but the bit of harshness is gone, spaciousness and delineation between instruments slightly increased, and overall timbre is improved. Again, subtle but very important improvements for me.

This approach isn't exactly the same as EQing the anechoic response since it's applying anechoic compensation to an in-room target, but it happened to give pleasing results in my situation.

 

[test1223]

Just about every desk setup suffers from reflections and modal issues. What (unaddressed) problem are you concerned about?

The 800Hz dip and 1.5 peak is a bit unusual for a speaker which should provide the opposite judging form the sound power.

With regards to your posted EQ, no, I have not tried it yet. Although, of that set, a 1dB 3.2 kHz reduction perhaps could work in terms of adding to what EQ I already have currently active -- but, I don't have the energy to A/B such small changes right now. Hmmmn... I think, quite realistically, I do not have any big expectation that it will reduce "harshness" in the way you think it will at my nearfield MLP. Because, well, my ears aren't hurting from excessive harshness or anything like that...

From my experience smaller changes in the 1-4kHz region are more important than bigger changes at other frequencies. Especially if you change the balance between these frequencies since the relative difference gets bigger.

 

[ernestcarl]

Doesn't really seem all that unusual -- to me. Over the years, I've seen many in-room Neumann and Genelec setup measurements that have many more seemingly "severe" random bumps and peaks.

The dip is largely caused by the desk. Remove the desk and away it disappears. The port resonance peak is... probably from the port -- alternatively, and/or a box depth resonance. Dominikz was the first to point that one out to me. I believe of the five (?) units of KH120s he measured it was much worse in one unit -- and similar to what I posted above. Perhaps, I could have (through the years) exacerbated the issue by stuffing the port several times which may have loosened the foam surround bits around the port hole. I have not investigated further.

KH120 nearfield in middle of room + BR port

*Measured two years ago

https://www.hifi-selbstbau.de/testberichte/fertiglautsprecher/470-neumann-kh-120a (original web link seems to have died. Perhaps relocated?)

 

[test1223]

Doesn't really seem all that unusual -- to me. Over the years, I've seen many in-room Neumann and Genelec setup measurements that have many more seemingly "severe" random bumps and peaks.

The frequencies where the peaks / dip are is a bit unusual. They shift with listening distance and vertical head position therefore it is hard to solve such a problem...

The dip is largely caused by the desk. Remove the desk and away it disappears. The port resonance peak is... probably from the port -- alternatively, and/or a box depth resonance. Dominikz was the first to point that one out to me. I believe of the five (?) units of KH120s he measured it was much worse in one unit -- and similar to what I posted above. Perhaps, I could have (through the years) exacerbated the issue by stuffing the port several times which may have loosened the foam surround bits around the port hole. I have not investigated further.

Okay interesting. In it's original state there shouldn't be a visible peak in the room curve but you might never the less hear the problem. I'm no fan of bass reflex designs in general but I also don't like bass shy speakers...

 

[thewas]

https://www.hifi-selbstbau.de/testberichte/fertiglautsprecher/470-neumann-kh-120a (original web link seems to have died. Perhaps relocated?)

Yes, they have changed a bit their website, here is the new one https://www.hifi-selbstbau.de/index.php/fertiglautsprecher/neumann-kh-120a

 

[ernestcarl]

The frequencies where the peaks / dip are is a bit unusual. They shift with listening distance and vertical head position therefore it is hard to solve such a problem...

Okay interesting. In it's original state there shouldn't be a visible peak in the room curve but you might never the less hear the problem. I'm no fan of bass reflex designs in general but I also don't like bass shy speakers...

Thank you… but, for the sake of my sanity and that of others, I try not to make mountains out of molehills.