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Speaker/Room Measurement Witchcraftery

S-Man, Your in room measurements I assume were taken from the listening position. first, use 1/12 smoothing.

Your sub should be brought at least 5db down imo. Your trying to compensate the 40hz dip with the sub but clearly you should find another placement for your subs . As you can see, you have a serious dip at from 35hz to 50hz. since you cross the sub around 80hz, due to how long those frequencies wavelenght are, as long as your sub are within 3.5 feet from the mains, the subs are <<time aligned>> with the mains. the rule is 1/4 wavelenght. 80hz wavelenght is 14 feet. 14/4 is 3.5 feet.


My experience with subs have been constant, they measure easily flat, at the LP, up to 60hz/80hz if you place them on the front wall, as close as you can from the front wall. this placement helps to remove dips at the LP because it bring the cancellation from the front wall up in frequencies. you should try it at least.

secondly, you have a serious dip at 100hz which is probably easy to deal with by moving your mains around. the 100hz is a cancellation from the front wall or maybe your listening position in relation to the back wall. try either to move your listening position, the 38% rules helps. do not place your LP at the 50% of the room length, nor the 25%!

good luck

Some very good points. Unfortunately I don't have any stands for the LS50.
In the past, when I did have stands but no microphone, I tried the boundary loading thing and didn't like the audible result.
I suspect my LP is around 38% from the back wall/window.

BTW, Lee from Stricktly Stereo considered my room to be a "good sounding room". That was using the current speaker positions for both Kii3 and CAOW1/ZRB.
He commented that he could "hear the room" but it was not intrusive. I totally agree that the 30Hz peak is audible. Lee was sat off axis, where the 30Hz lump is more audible than the hot spot.

LS50/ZRB at my friend's house with a much larger room sounds better. Actually I put it in the "best systems ever" thread. That's why I had to have a pair of LS50s.
Mine ought to sound even better because I don't have to look at orange drive units :D
 
Some very good points. Unfortunately I don't have any stands for the LS50.
In the past, when I did have stands but no microphone, I tried the boundary loading thing and didn't like the audible result.
I suspect my LP is around 38% from the back wall/window.

BTW, Lee from Stricktly Stereo considered my room to be a "good sounding room". That was using the current speaker positions for both Kii3 and CAOW1/ZRB.
He commented that he could "hear the room" but it was not intrusive. I totally agree that the 30Hz peak is audible. Lee was sat off axis, where the 30Hz lump is more audible than the hot spot.

LS50/ZRB at my friend's house with a much larger room sounds better. Actually I put it in the "best systems ever" thread. That's why I had to have a pair of LS50s.
Mine ought to sound even better because I don't have to look at orange drive units :D
get yourself stands :)
 
BTW, Lee from Stricktly Stereo considered my room to be a "good sounding room". That was using the current speaker positions for both Kii3 and CAOW1/ZRB.
He commented that he could "hear the room" but it was not intrusive. I totally agree that the 30Hz peak is audible. Lee was sat off axis, where the 30Hz lump is more audible than the hot spot.

I thought that the Kii Three sounded great in your room and that was without getting out the microphone or experimenting with positioning. I only had a brief listen to the CAOW1/ZRB combo. Your room has the potential to sound very good indeed, not least because its length, width and height are all rather different, so the major modal frequencies are spread out somewhat. With the Kii Three placed in the same spot normally occupied by your CAOW1/ZRB, there was some audible "purring" during louder passages when I sat off to the side. I would have pegged that at closer to 50Hz, but it was months ago now and my ears are by no means golden. This sort of thing is to be expected at boundaries and I doubt that moving the speakers will help with this. It was not intrusive and I have certainly heard much worse. I am confident that you can achieve better results than your charts suggest.
 
I would be interested to see waterfall plots and perhaps spectrograms (all available using your mdat files of the measurements in REW).

These will tell is about timing - how long the sound takes to die down, or even if there is some external sound, such as traffic.
 
I think there is a lot more to it that just FR. Compare my CAOW1 (DIY) speakers to LS50s (red), nearfield:
IIRC this is with ports blocked and active crossover in place. Also, until I figure out gating, there's loads of room mixed in, so please take with a pinch of salt:

LS50_red_versus_Murphy.jpg


From the above I would assume the LS50s sound a bit brighter due to the increase in the presence region. But of course this is only the on-axis response.
In reality the pivotal difference is that the LS50 sound cleaner and faster... brass instruments sound brassy instead of slightly fuzzy. Maybe this is attributable to less box colouration (the LS50s are remarkably dead on the knuckle rap test) or maybe it's lower distortion (I've always wondered if the OW1 can really handle a 2nd order acoustic crossover at 2.5KHz) or both? Whatever it is, I doubt my rudimentary measurements are going to show it.

Most of what you describe is high frequency related, partly due to the LS50 tweeter being 2 or 3dB too hot, which is why you see the shelving in the FR above 1.5kHz:

fr_listeningwindow.gif

Listening window 20Hz - 20kHz (measured @ 2m, plotted @ 1m) (anechoic)
Response curve is an average of five measurements: on-axis, 15 degrees left and right off-axis, 15 degrees up and down off-axis
https://www.soundstagenetwork.com/i...&catid=77:loudspeaker-measurements&Itemid=153

But the waterfall is very clean meaning no cabinet nor driver resonances, which can affect clarity:

1212KEF50fig9.jpg

KEF LS50, cumulative spectral-decay plot on HF axis at 50" (0.15ms risetime). (gated)
Read more at https://www.stereophile.com/content/kef-ls50-anniversary-model-loudspeaker-measurements
 
REW really is rather wizzy!

I have just found the room simulation thingy and it would appear to tally very well with my measurements. I have aligned the x axes:

Simulation_versus_measurements.jpg


My LP is ~37% from the back wall/window.

My conclusion is that my speakers are so damned accurate at LF that they can be used to measure the room! :cool::D
 
Maybe. Perhaps you could explain the correct way to measure speakers In room, so I can correct my friend?

If he wants to give me a call, I would be happy to help. Probably of more use to him are the step-by-step guides I found on the Internet a while back. I have the links saved somewhere. I will try to dig them up.
 
Most of what you describe is high frequency related, partly due to the LS50 tweeter being 2 or 3dB too hot, which is why you see the shelving in the FR above 1.5kHz:

I think its a little hot as its a coaxial driver and drops a fair bit off axis. They certainly don’t sound over-bright with a typical toe-in so they are crossing a fair bit behind the listening seat IME. No one listens to anything on axis at a metre!
 
I think its a little hot as its a coaxial driver and drops a fair bit off axis. They certainly don’t sound over-bright with a typical toe-in so they are crossing a fair bit behind the listening seat IME. No one listens to anything on axis at a metre!

According to Soundstage the measurement above, taken at 2 metres, "Averages five frequency response measurements and plots them as a single frequency response. The five frequency response measurements that are averaged for the Listening Window are: on-axis, 15 degrees left and right off-axis, 15 degrees up and down off-axis."

The following plot, with measurements at 2m, shows that the tweeter response is still exaggerated at 15º:

fr_on1530.gif

Frequency response 20Hz - 20kHz (measured @ 2m, plotted @ 1m)
Top curve: on-axis response
Middle curve: 15 degrees off-axis response
Bottom curve: 30 degrees off-axis response
https://www.soundstagenetwork.com/i...&catid=77:loudspeaker-measurements&Itemid=153
 
I think the LS50 is a bit hot around 2.5KHz. My pal actually uses a budget vintage analogue graphic equaliser to take them 2 or 3 dB down at that frequency.
in his system they undoubtedly sound much better that way versus bypassing the graphic equaliser.
In my system, I didn't find the ALSAmixer software equaliser helped in the same way. I prefer to tune the mid forwardness with careful choice of cables :eek::eek::eek::eek::eek:
 
as we can see the forwardness is the ls50 when listened on axis. when 30 degree off axis, it make the whole 2khz to 10khz flat. when I had my kef ls50, i preferred the ls50 with no toe in as well. but the metallic tonality was still apparent even if it measured flat off axis.
 
Interesting. I do like the LS50, but I’ve only heard them in a very high-end system (Conrad Johnson etc). I didn’t notice anything odd or metallic about them at all, very open and natural on the jazz material I favour with a surprising sense of scale and impact for such a tiny speaker.
 
I heard the LS50 at Dave's place with the ZRB some time ago; I had a pair then and took them around for comparison. I was amazed at how clean they sounded with the ZRB. I would like to hear a pair of LS50s again; perhaps I'll end up buying some for a third time! I still cannot quite account for the treble performance. On the one hand they have this forward presence region, which does not offend me - perhaps it is forward in the right part of the presence region for my ears (I do have issues, however, with a peak at 3Khz with my current speakers). On the other hand, I am going to have to repeat myself and mention that trumpet problem again. Well, Ayya has mentioned the metallic issue again, and we've already been through that discussion a year or two ago (Dave and I heard it once, then never heard it again, as far as I remember). I've still not heard any explanation as to why the LS50 cannot convey Freddie Hubbard in full reach or Miles with harmon mute, and certainly nothing in the measurements explains it. However I believe Dave has heard much better results from trumpet recordings since.

Regarding measurements, just an aside, but I was recently looking through all the various measurements of speakers I've taken over the last 2 or 3 years, and I noticed two or three things. One was that measurements taken with REW do not correlate very precisely with those taken with Dirac. The second is that I have certain room mode characteristics that are the same for virtually all speakers (e.g. 40Hz peak followed by big trough at 63ish). The third is that some of these speakers sounded completely different when their FR was almost identical in all but the presence region.
 
I think that quite gross one-off "colouration" we heard must have been an aberration. I have never heard anything like it from my new LS50s (mind you, the new black drivers obviously sound much calmer than those orange ones :)) or any others. I wonder if AK's "metallic issue" is perhaps what others hear as forwardness?

On your 2nd para...
The REW room simulator is quite enlightening and can certainly save a lot of moving and measuring - or buying of speaker stands. I urge anyone to try it out and "drag" the sub(s) around and it soon becomes apparent that the room peaks are troughs are only modestly affected by the sub position(s). The only arrangement that seems to defeat the room modes is the "Move subs to wall midpoints" one, but this would totally destroy any time alignment and I have no idea what effect it would have with stereo bass (like mine). So far I haven't found any reason to change my opinion that putting a "flat" signal into a real room sounds better than eq'ing the signal to counteract the room effects. OTOH I have heard a system with gentle eq that sounded superb, so I guess it's all a question of balance and moderation.



I will not be able to take any more measurments for few days.
 
The "metallic" coloration is probably brightness. When swapping my atc scm7v3 and p3esr and the kef ls50, they all measured almost precisely the same (proof that in room response FR trumps any small anechoic difference in the speaker "built in FR").

however, the atc scm7v3 and p3esr had very similar sound. The kef ls50 imo sound edgy in comparison, like overly crisp. Impressive at first, but not as musical to me, too analytical. Without talking about the boomy bass that adds 10% THD at 100hz when driven at 85db. Imaging is very good, but I heard a distinct colouration in The timbre of instruments, every sounds had that sort of coloration, making everything sound the same. In 3 different room, with different front end, it was obvious that the p3 and scm7 shared very much the same sound, and the kef ls50 was brighter.
Spend money to make the measurements better and the sound (most likely) worse :confused:
how can you find the best speaker placement without stands?

why do you think when you have better measurements you have worst sound?
 
I urge anyone to try it out and "drag" the sub(s) around and it soon becomes apparent that the room peaks are troughs are only modestly affected by the sub position(s).
ok. Then you need to look at your Listening position (where your mic is) which is directly in a room mode.
as a experiment, place each sub against the front wall, behind each speaker. then move your mic (listening position) around. you should be able to find a area that give the flattest result. then, dont move the mic (LP) around anymore. now take each sub and move them around to find the best Frequency Response.

So far I haven't found any reason to change my opinion that putting a "flat" signal into a real room sounds better than eq'ing the signal to counteract the room effects.
problem with trying to EQ room problems, especially dips like yours that are 15db deep which is clearly a room mode,its well known that room eq can help to reduce peaks, not really helpfull to improve dips.

Digital room correction is a great in untreated rooms, but Id do everything I can to at least deal with your 40hz dip and also the 70hz and 100hz dip.
 


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