measuring my P/A speakers

[stoneeh]

I've measured these on-axis (between mid en high driver, aimed with my laser to be shure the mic was on the correct hight!). Measured at 1m, 2m and 5m distance (the REW screenshots are from the 1 meter measurement). I've used my calibrated Isemcon on REW on my MacBook, nothing in between. The curve didn't flatten out while going from 1 tot 5 meters, the accuracy of the measurement did however... Compression / limiting of the DSP was off while measuring, and when pushed towards 90% level only the distortion level in low mid en mid went sky-high..... the frequency curve did not change. Off course I realize that P/A speakers don't measure ruler flat like Hi-Fi or studio monitors. but most of my other P/A speakers measure within reasonable margin " flattish"... my point is that there is a factory preset on these Speakers (called Linear 5!!!) that's named "flat" and it's not! the discussion of how a P/A speakers should measure for a good reference is very interesting! IMHO, a P/A speaker should measure "flat" from 1 to 5m on axis out of the box (near/midfield) so it's predictable and reliable and easy to setup. Maybe not important, but when mixing a band (random band on a random stage) you LPF/HPF, EQ, gate, compress, limit, FX etc... each channel individually; there you make the mix. Setting up the system, before the soundchecks, starts with Arta / pink noise en some sweeps for time delay/phase... also you want to disable the feedback: if a speaker has it;s own Curve / boosted highs and mids, then Feedback suppression is a big pain in the ass! if you mixing several bands in one night on the same stage, and someone brings on their own soundguy and plug-in the Yamaha DM7 or DiGiCo mixer, the whole preset is instant unusable due to the curved FR!

The only info that's missing now is basic measurement setup, meaning GPM, 4pi (on stand), etc. It's often possible to discern this from the curves themselves, but here I'm at a loss - the measurement contains too many ripples where they shouldn't be for a GPM, and too much low frequency information / resolution for a gated 4pi.

If it's 4pi, please name the measurement height and gate length. Also describe the setup in detail, meaning what kind of stand / tripod you were using, etc. Also, and this would go for a GPM also, how far the nearest reflective object (wall, car, ...) was from the measurement setup.

You've gotten some lackluster advice from users obviously lacking knowledge and/or experience regarding near field vs. far field. Speakers this size are already essentially in the far field at 1m distance, and even below. Frequency response indeed won't change much from 1 to 5 meters. The only factors really able to cause a difference are smaller angles of the individual drivers to the mic at larger distances (but that's negligible in that case), and air dampening at high frequencies (also still negligible at 5 meters).

Some active PA speakers have (documented & switchable, like for example Yamaha D-Contour, or entirely undocumented and out of user control) adaptive EQ, meaning EQ depending on level / volume - but since you already measured at various levels and discovered that the response didn't change, that can obviously be ruled out as the cause of the uneven frequency response.

 

[Toni Mas]

The vast majority of amplified pa speakers with DSP currently sold offer similar presets that offer ready to use non flat responses to adapt to different use cases. I admit that It is strange and confusing that HK calls flat something that obviously is not flat. But as It is an advanced product that allows advanced users full customization of the presets according to their needs and taste, why bother with a preset you do not find useful for you? According to the manual these presets are mere suggestions and you are totally free to make whatever change you consider useful.

Did you try to use their DSP software to check what this "flat" preset is exactly made of?

 

[Arbr4]

The only info that's missing now is basic measurement setup, meaning GPM, 4pi (on stand), etc. It's often possible to discern this from the curves themselves, but here I'm at a loss - the measurement contains too many ripples where they shouldn't be for a GPM, and too much low frequency information / resolution for a gated 4pi.

If it's 4pi, please name the measurement height and gate length. Also describe the setup in detail, meaning what kind of stand / tripod you were using, etc. Also, and this would go for a GPM also, how far the nearest reflective object (wall, car, ...) was from the measurement setup.

You've gotten some lackluster advice from users obviously lacking knowledge and/or experience regarding near field vs. far field. Speakers this size are already essentially in the far field at 1m distance, and even below. Frequency response indeed won't change much from 1 to 5 meters. The only factors really able to cause a difference are smaller angles of the individual drivers to the mic at larger distances (but that's negligible in that case), and air dampening at high frequencies (also still negligible at 5 meters).

Some active PA speakers have (documented & switchable, like for example Yamaha D-Contour, or entirely undocumented and out of user control) adaptive EQ, meaning EQ depending on level / volume - but since you already measured at various levels and discovered that the response didn't change, that can obviously be ruled out as the cause of the uneven frequency response.

Hi,

As you know, near field measurement and farfield measurements have different protocols. The graphs on the sites of most (not all) P/A audio companies display the On-axis response (and then 15-30-60 degr. slopes). Your GPM/4Pi 3D measurement is more suitable for larger P/A systems (like my 32x L'accoustics line array system for big festivals >10.000 people). I use Arta for these concerns and sometimes up to 16 mics to get the correct null filling, phase and time correction and coverage. For this smal system, a triple setup with REW does the trick to define the actual Frequency response (to determine if flat is really flat).

Back to the measurement. Nearfield measurement are don on axis at exact 1 meter distance with the measurement mic. pointed exact between LF and HF driver. To exclude most reflections, the speakers is placed in free space (meaning nog objects within a radius > 20m) and 2m above ground level (as well does the mic). So to get back to the lackluster advice from users who lack knowledge; let's compare apples with apples and not apples with oranges of whatever.

 

[Arbr4]

The vast majority of amplified pa speakers with DSP currently sold offer similar presets that offer ready to use non flat responses to adapt to different use cases. I admit that It is strange and confusing that HK calls flat something that obviously is not flat. But as It is an advanced product that allows advanced users full customization of the presets according to their needs and taste, why bother with a preset you do not find useful for you? According to the manual these presets are mere suggestions and you are totally free to make whatever change you consider useful.

Did you try to use their DSP software to check what this "flat" preset is exactly made of?

It bothers me that the stating point "flat' is misleading because it's not flat. like I said before, most other comparable boxes of other brands are more ore less flat. I did use the DSP and did try to find out how the standard presets are tweaked and I did make a flat preset... I've mentioned this quit a few times. When tuning to real flat, the sound of the did fall apart; it seems like there's a fault in the time alignment between the drivers (high is behind mids; you can hear this in articulation). So HK is masking a design error by boosting highs and lows (so the FIR filter error isn't that obvious). Or they made a decision that's misleading; calling their speaker "linear" and calling their preset "flat".

 

[Toni Mas]

When tuning to real flat, the sound of the did fall apart; it seems like there's a fault in the time alignment between the drivers (high is behind mids; you can hear this in articulation).

Mmmm... Sorry but I don't understand this. If It is tuned to real flat, It should both measure and sound flat...

Did your measurements confirm that the response was actually flat?

PD: in fact with no eq applied most pa speakers do not sound flat. They rather sound thin because diffractions losses (baffle step) are not corrected to preserve max SPL in the midrange that is the usual priority. PA and Hifi have diffrrent priorities.

 

[ChrisG]

I have hands-on experience with those speakers, and others from that manufacturer. Haven't been particularly impressed with anything from them that I've tried. The smiley-face sound will probably impress on a quick demo in a shop.

FWIW, I'd keep the flattened response curve you've worked out, and call it good. It looks like their "LF boost" profile provides a LOT of boost and really extends the LF, so you could probably push yours for flat down to 70-80Hz without too much concern.

Also, there are a lot of misconceptions about PA speakers in this thread. To the commenter above, the baffle-step losses would show in the frequency response measurements. They have been accounted for.

 

[Toni Mas]

Also, there are a lot of misconceptions about PA speakers in this thread. To the commenter above, the baffle-step losses would show in the frequency response measurements. They have been accounted for.

Looks like misunderstood...Of course baffle step losses are accounted for by the "flat" preset. But It also goes farther adding some boost at both frequency extremes. As explained in their web page, this preset is intended for users that would use these speakers without subs and would apreciate this boost. After all as any 12 incher, without some eq It will sound kind of bass shy. It seems obvious that this preset is not intended for use with subwoofers, but as i said, calling this preset "flat" may cause confusion. But i dont think It is a reason for blaming HK. After all most speakers with DSP offer now these smiley presets, even if they won't match anybody's taste and needs. If you don't like them, simply ignore or customize them. And when It comes to customize, i find that HK's software offers huge flexibility.