Klipsch R-15m vs RP-150m linearity

[yepimonfire]

I recently upgraded my fronts from the R-15ms to the RP-150m, while the sound quality is more refined and detailed with the Premier series, I was curious whether or not they were much more accurate than the R-15m, so I took measurements at 1m.

The 150hz hump is ue to the fact the R15m is near the sidewall, as it's been placed in surround duty. I recently treated my room acoustically, so it can be assumed everything above 400hz is likely accurate. (no bass traps). Mic still refuses to pickup past 16khz. Rolloff is likely due to close proximity not accurately capturing the ports addition, as I have measure -3dB at 50hz with both models.

Surprisingly, they are very similar, they do sound similar subjectively, the RP-150m sounds a tiny bit brighter, and has tighter imaging with a much wider sweet spot compared to the R-15m. While I haven't included the graph, the distortion is also a lot lower, and port noise even at high spl below the tuning frequency is non existent thanks to the tractrix port. I also noticed the Premiers still have a bit of authority down to about 40hz -6dB at the MLP, where the R-15ms take a nosedive in sound quality and useful output below 50hz, giving way to port noise and cone breakup.

 

[JRT3]

Thank you for you tests and comparison!

 

[everettT]

Might be better to take a close mic measurements.

 

[TheWarrior]

What thickness/quantity of absorption did you just add? The midrange looks to be better complimented by diffusers rather than having more of its energy absorbed. Or you went nuts with 2" rigid fiberglass.

 

[yepimonfire]

What thickness/quantity of absorption did you just add? The midrange looks to be better complimented by diffusers rather than having more of its energy absorbed. Or you went nuts with 2" rigid fiberglass.

I actually just used 2" Auralex wedgies. I don't really have any major issues with bass, I was mostly concerned with the flutter echo and smearing of imaging from first reflections, which the Auralex solved.

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[TheWarrior]

I actually just used 2" Auralex wedgies. I don't really have any major issues with bass, I was mostly concerned with the flutter echo and smearing of imaging from first reflections, which the Auralex solved.

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I would strongly recommend adding diffusers to try and lessen the huge swings seen in those measurements. Your midrange is 10 dB lower from 500hz (upper bass) until the speakers try to go into a breakup mode with that big upswing above 10khz.

Using 2" absorbers for first reflections only serves to absorb some of the high break up modes which would be better handled by tone controls to minimize the break up mode all together rather than let it propagate and have to then be absorbed. First reflections add significantly to perceptions of envelopment and apparent source width.

Food for thought!

 

[shadyJ]

You sure that 10 kHz stuff is breakup? With that tractrix horn, I would want to see off-axis measurements to make determinations. Its behavior isn't really known, at least publicly.

 

[yepimonfire]

You sure that 10 kHz stuff is breakup? With that tractrix horn, I would want to see off-axis measurements to make determinations. Its behavior isn't really known, at least publicly.

I don't believe its breakup, otherwise it would show up in distortion measurements. Checking the measurements again, at 10khz the THD is 0.56% at 12.4khz where the peak centers, distortion is 0.86%. It's probably just the horn itself.

I have some off axis measurements I can post. Out to about 70° the response compared to on axis is similar. The response is pretty much flat +-45° off axis. After 45° everything above 1.5khz is attenuated evenly by about 3dB, but follows the same curve, indicating that the horn is evenly dispersing at all frequencies. After about 65°, frequencies above 12.4khz begin rolling off, with the high frequency response being +-3dB from 1.5khz-12khz, and -6dB at 16khz. Vertically, it follows the same pattern measured above the woofer, but displays a stronger HF roll off measured below, likely due to interference at the xover point.

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[yepimonfire]

I would strongly recommend adding diffusers to try and lessen the huge swings seen in those measurements. Your midrange is 10 dB lower from 500hz (upper bass) until the speakers try to go into a breakup mode with that big upswing above 10khz.

Using 2" absorbers for first reflections only serves to absorb some of the high break up modes which would be better handled by tone controls to minimize the break up mode all together rather than let it propagate and have to then be absorbed. First reflections add significantly to perceptions of envelopment and apparent source width.

Food for thought!

Comparing the response to one peak is pointless. Measured 9' away on axis the 12khz peak disappears, with and without room treatments. The worst variations with room treatments occur below 500hz, with some peaks and dips. Using an equalizer to trim 12.4khz 9dB so that it measures flat at 1m causes it to measure -9dB at the listening position, and it sounds veiled like the eq has obviously made it worse. I believe the horn starts becoming directional at 10khz, giving way to beaming at 12.4khz, which could cause those close measurement spikes. If the horn is picking up the sound below 12.4khz, and dispersing it in a 90° pattern, the total energy is going to be spread along that pattern, whereas 12khz is going to be a narrow beam, that's the only explanation I can think of to explain why it measures like that close up, it also explains the off axis behavior, with the rolling off at 12khz but remaining flat below 10khz. I can tell you a 10dB spike at 12.4khz normally would be painfully bright, yet these don't sound bright at all. I have a pair of Polk OWM3's that display a 5dB spike at 12khz, which shows up both at close range and at the seating position, and it actually does sound bright in comparison.

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[TheWarrior]

You sure that 10 kHz stuff is breakup? With that tractrix horn, I would want to see off-axis measurements to make determinations. Its behavior isn't really known, at least publicly.

In my best Obi Wan voice, "That's no horn, its a dome tweeter with a wave guide."


@yepimonfire
All speakers become directional as frequency increases. The advantages of horn loaded speakers is to increase the distance traveled before those millimeter wave lengths succumb to propagation loss - the roll off any speaker shows at high frequency.

A single measurement is only one piece to the puzzle of your room, yes. I didn't go in to bass because that is entirely controlled by the room below 200 hz. Above that, I still maintain diffusers are the way to go based on the variation in sound level through the frequency range.

Going in to more detail would require more info on the room and arrangement. I've been reading a lot and trying to practice so that anyone's room becomes a puzzle to solve, I really enjoy it.

Thank you for sharing your measurements. Just trying to help!

 

[yepimonfire]

In my best Obi Wan voice, "That's no horn, its a dome tweeter with a wave guide."


@yepimonfire
All speakers become directional as frequency increases. The advantages of horn loaded speakers is to increase the distance traveled before those millimeter wave lengths succumb to propagation loss - the roll off any speaker shows at high frequency.

A single measurement is only one piece to the puzzle of your room, yes. I didn't go in to bass because that is entirely controlled by the room below 200 hz. Above that, I still maintain diffusers are the way to go based on the variation in sound level through the frequency range.

Going in to more detail would require more info on the room and arrangement. I've been reading a lot and trying to practice so that anyone's room becomes a puzzle to solve, I really enjoy it.

Thank you for sharing your measurements. Just trying to help!

I'm confused whether you're saying the breakup is due to the driver or to the room, room treatments cannot fix driver break up. My point was that the peak is only observed near field, using an equalizer to smooth it out causes a large dip at a distance, and it sounds bad. The response anywhere else in the room is much different.

It doesn't matter if the driver is a dome or not, its still a horn speaker. Never heard of a dome compression driver? From Red Spade Audio:

A compression driver (CD) is a professional loudspeaker driver usually intended for mid or high frequency use with waveguides or horns. They can be thought of as similar to hifi dome tweeters in that they have a dome diaphragm and a motor. The main physical difference is that the dome is coupled to an exit tube via a phase plug where the dome is large than the exit. Hence it has a compression ratio, defined as the ratio of the area of the dome to the exit.

As you can see in the picture, the 1" diaphragm sits behind a phase plug, which has a (roughly) 1/4" exit that is coupled to the horn via a circular throat.

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[TheWarrior]

I'm confused whether you're saying the breakup is due to the driver or to the room, room treatments cannot fix driver break up. My point was that the peak is only observed near field, using an equalizer to smooth it out causes a large dip at a distance, and it sounds bad. The response anywhere else in the room is much different.

It doesn't matter if the driver is a dome or not, its still a horn speaker. Never heard of a dome compression driver? From Red Spade Audio:

As you can see in the picture, the 1" diaphragm sits behind a phase plug, which has a (roughly) 1/4" exit that is coupled to the horn via a circular throat.
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Break up mode was alluding to the rise in amplitude before rolling off around 14khz. More on that later....

Diffusers, well placed, could smooth out your mid range response - is really all I wanted to suggest for further improvement.

But of course I go too deep/off topic:





From the same site, this is the anatomy of a compression driver. Please note how the diaphragm is placed behind the magnet and pole pieces, and then the throat is placed at the front to connect to a horn. (It is confusing because the beginning of a horn is called the throat as well) Energy is multiplied within this chamber and then released following the geometry of the horn ensuring a greater distance can be covered before high frequencies lose energy/relative sound level. This is a completely different design than using a dome tweeter and placing a waveguide/horn in front of it which can still yield increases in efficiency. (which is perfectly legitimate as a means to modify directivity of a HF transducer before summing with mids/woofers)

That Propagation Loss I mentioned earlier really comes in to play with larger venues where those high frequencies with tiny wave lengths really suffer dramatic roll off, as measured in a commercial theater, as a result of distance from speaker to ear/mic.

Back to that break up mode, one thing I forgot about was that if you are using Audyssey, it seems to have a tendency to cause a rise in amplitude before steeply rolling off. This stems from their design approach of basing research on the old cinema 'X-Curve' which attempted to describe an objective target performance for large commercial cinema's. The unfortunate result of basing a home room correction system on that is you impose an unnaturally steep roll off (propagation loss of a commercial theater rather than that of a domestic living room) which can seriously limit the extension of high quality tweeters.
For more info: 'The Measurement and Calibration of Sound Reproducing Systems'

In case you can't tell, I don't often get to 'chat' with people about this boring stuff. Hope I didn't impose too much, and I am glad you enjoy your new speakers!

 

[yepimonfire]

Break up mode was alluding to the rise in amplitude before rolling off around 14khz. More on that later....

Diffusers, well placed, could smooth out your mid range response - is really all I wanted to suggest for further improvement.

But of course I go too deep/off topic:





From the same site, this is the anatomy of a compression driver. Please note how the diaphragm is placed behind the magnet and pole pieces, and then the throat is placed at the front to connect to a horn. (It is confusing because the beginning of a horn is called the throat as well) Energy is multiplied within this chamber and then released following the geometry of the horn ensuring a greater distance can be covered before high frequencies lose energy/relative sound level. This is a completely different design than using a dome tweeter and placing a waveguide/horn in front of it which can still yield increases in efficiency. (which is perfectly legitimate as a means to modify directivity of a HF transducer before summing with mids/woofers)

That Propagation Loss I mentioned earlier really comes in to play with larger venues where those high frequencies with tiny wave lengths really suffer dramatic roll off, as measured in a commercial theater, as a result of distance from speaker to ear/mic.

Back to that break up mode, one thing I forgot about was that if you are using Audyssey, it seems to have a tendency to cause a rise in amplitude before steeply rolling off. This stems from their design approach of basing research on the old cinema 'X-Curve' which attempted to describe an objective target performance for large commercial cinema's. The unfortunate result of basing a home room correction system on that is you impose an unnaturally steep roll off (propagation loss of a commercial theater rather than that of a domestic living room) which can seriously limit the extension of high quality tweeters.
For more info: 'The Measurement and Calibration of Sound Reproducing Systems'

In case you can't tell, I don't often get to 'chat' with people about this boring stuff. Hope I didn't impose too much, and I am glad you enjoy your new speakers!

Hey I always am up for more learning. BTW that driver doesn't roll off at 14k, my mic does. I don't use audyssey.

I do agree diffusion mixed in with absorption would help, but to be honest I actually prefer a nearly dead room, in small rooms, I've never experienced early reflections adding anything to the sound stage except confusion. Before adding treatments it was so bad I couldn't even achieve a phantom center image in two channel mode. In rooms properly designed for acoustics, maybe, but a majority of living rooms are really a crap shoot. For example, on the left side of my room I have a completely bare wall except for a sofa, on the right side of the room I have a recessed window with mini blinds that add some diffusion. The frequency response of my left speaker and right speaker are vastly different because of this, and the sound stage sound left heavy. Equalizing out the variations is pointless because moving a few feet will change the response again. 90% of the time, the size of the soundstage is already determined by the mix. Movies mixed for cinema are mixed to be played back in an acoustically treated environment, I don't see why it should be different at home.

For music, things like classical already contain spatial information, for every thing else, I just use Dolby Surround, which does a much better job of increasing the sense of space than a 12' wide room with unpredictable reverb.

Does diffusion actually solve the above mentioned problems?

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[TheWarrior]

Hey I always am up for more learning. BTW that driver doesn't roll off at 14k, my mic does. I don't use audyssey.

I do agree diffusion mixed in with absorption would help, but to be honest I actually prefer a nearly dead room, in small rooms, I've never experienced early reflections adding anything to the sound stage except confusion. Before adding treatments it was so bad I couldn't even achieve a phantom center image in two channel mode. In rooms properly designed for acoustics, maybe, but a majority of living rooms are really a crap shoot. For example, on the left side of my room I have a completely bare wall except for a sofa, on the right side of the room I have a recessed window with mini blinds that add some diffusion. The frequency response of my left speaker and right speaker are vastly different because of this, and the sound stage sound left heavy. Equalizing out the variations is pointless because moving a few feet will change the response again. 90% of the time, the size of the soundstage is already determined by the mix. Movies mixed for cinema are mixed to be played back in an acoustically treated environment, I don't see why it should be different at home.

For music, things like classical already contain spatial information, for every thing else, I just use Dolby Surround, which does a much better job of increasing the sense of space than a 12' wide room with unpredictable reverb.

Does diffusion actually solve the above mentioned problems?

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GIK Acoustics 'Polyfusor'
GIK Diffusors

As you can see there are many different ways to 'scatter' sound. Ultimately the objective is provide a more diffuse environment for all listeners. If you're going to treat a room, a mix of scatter and absorption is recommended. But the general rule is, if you're going to absorb it, you have to absorb it all: meaning everything from boomy bass to piercing highs. And the products that do each of those things are very different in size. Obviously you can go nuts buying dozens of panels, but for those of us less well heeled individuals, measurements around the room go a long way to identifying ideal locations for absorption/diffusion.

The top method is one I learned about from Harman. I had not seen this type of device before. It allows for equal scattering of all frequencies while also absorbing some of the highs and mids, something I think would be of particular interest to you, and also my answer to your question.

Another very basic type of scattering device is a bookshelf. Having a few of those around would not hurt either!

Back to your room and set up: You mention things changing if the speaker moves. Inches matter! But the human ear is a remarkable measurement device that is worth trusting. Get your Front LR spread apart and toed in so that the sound is similar at every seat. You don't need a mic for this. Keeping them too far from the wall behind can also produce midrange cancellations as out of phase energy bounces off the wall behind and recombines with the direct sound before reaching the ears, thereby canceling it out.

What you do need a mic for (and one that can at least do 20 hz- 20khz) is locating overly excited wall reflections (which can be predicted on paper too, FYI) as well as Listening Position measurements that provide a map of troubled frequencies that need treatment beyond tone controls. That requires a lot of time as well as reading to understand exactly what you are trying to do. Most people don't seem to want to go that far and will either live with it, or pay someone.