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Where do you crossover your Klipschorn and subwoofer for 2 ch. (plus sub) music?


Rudy81
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I just finished setting up my new RSW-15. This is one nice sub for music! I am wondering where you Khorn experts crossover your Khorn to the subwoofer? I took some ETF readings of my system once it was calibrated with ETF and then Audyssey. I currently have the Khorns crossed over at 60Hz. but it looks like I may have to crossover a little higher. As you can see by this plot, there is a bit of a response drop once the Khorns are on their own. Ideas?

post-10337-13819512506898_thumb.jpg

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I have a REL subwoofer and crossover by 'ear' as recommened by REL. It will probably disturb you to hear that my crossover point is 28hz. Too many factors to do it by a calculation. The room being the biggest one. I think most folks have them crossed over way too high and that is why they 'boom'. Most of the time I cannot tell if my sub is even on. It is very subtle and blends well.

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I just figure there must be a point at which a Khorn is better than a sub and vice versa. Subs are designed to go low and the right sub will do that well. I'm guessing there must be point in the bass bin's performance where a sub will do a better job of reproducing a particular frequency.

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You should set the crossover about 1 octave above the lower limit of the main speaker. I think you are looking at a sub set too loud and some destructive cancellation. I had a similar (or the same) problem with my La Scalas. A horn delays the phase about 90 degrees from a direct radiator.

Turn your sub down a bit and play with the phase control. I'll bet you can eliminate part of that dip. However, the K-horn has a double dip between 80 and 100 Hz. See the AES paper I've attached.

AES_Preprint_re_LaScala.pdf

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You should set the crossover about 1 octave above the lower limit of the main speaker. I think you are looking at a sub set too loud and some destructive cancellation. I had a similar (or the same) problem with my La Scalas. A horn delays the phase about 90 degrees from a direct radiator.

Turn your sub down a bit and play with the phase control. I'll bet you can eliminate part of that dip. However, the K-horn has a double dip between 80 and 100 Hz. See the AES paper I've attached.

Thank you for all the information. Unfortunately, the one shortcoming of the RSW is that it only has a 0 or 180 phase control. It is not selectable as other subs are. I will just have to play with various options and levels and see which is best.

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John:

In looking at the plots from the paper, it is easy to see where both the Khorn and the La Scala start losing dB pressure near the 100 Hz. point. Yes, the Khorn can go down to 30 or so Hz, but at a greatly reduced pressure level. (Please correct me if my impressions are incorrect.) My goal is to have a relatively flat response across the majority of the spectrum. This is what has led me to beleive that brining the sub crossover up is the way to go.

BTW, when I ran some readings on the sub vs. the Khorn, I found that the phase at 0 best fit the Khorn woofer. At 180 it was clear they were fighting each other. I will post that graph later today.

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Rudy81,
Well, I have your RSW15 sub and Klipschorns, as well as a Belle Klipsch Center for "wide stage stereo"....

I'm in a different room, and tastes differ, but, after listening to the system with crossovers all over the map, for music (80% classical, big orchestras, 20% Jazz, pop, film), adjusting it by ear, I really prefer crossing it over at 40 HZ, because the Khorns sound so much better (tighter, cleaner, better transients) than the sub above that.
For some classical music, I actually turn the sub down a bit. In addition, on some of the SACD re-dos of old master tapes from the 1950s & '60s, there is a powerful room rumble from the original locale --- even audible on Khorns alone. With the sub, the room rumble is quite annoying, so the sub gets turned down even more when we are playing those disks.
Obviously, seating position and the room can make a powerful difference. In our old house in California, from the listening area, ONE Khorn had a dip centered at about 80Hz, going from just below 70 to about 90, and the other one DIDN'T! When I finally got around to switching them, the dip stayed with the corner, and didn't travel with the Khorn! It was something about that corner. The room was symmetrical, except for furniture, which included two big file cabinets. In both Khorns, there was a moderate peak at 40 - 50, and another one at 125 - 200. We had the floor super braced with Stonehenge like lintels (as recommended by an article in either High Fidelity or Stereo Review), and the low end below 70 was not only smooth to 31.5, it was actually boosted there. We lost that boost when we moved to Oregon.
In our present house, from listening position, with the RSW15 tested with each Khorn separately, we tolerate a dip at 80, in the name of the cleanliness described above. The sub goes down to 25 easily, and 20 with slight attenuation. Both Khorns have a peak at 40 - 50, the aforementioned dip, and a peak at 150. In this room, they go down to 35, then fall rapidly. The Belle center has a peak at 60, then drops out below that.
We're in the middle of a room transition right now, after which I'll access
Room EQ Wizard and see what happens. The data above was produced with both a corrected RadioShack meter, and an Audio Control Spectrum Analyzer ... they read similarly in the bass, but not at all in the treble!
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If you measured this with a sweep in an anechoic chamber stop reading right here.

If not, then what you are seeing is either room node cancellation, phase cancellation between the K-Horns & sub or more likely a combination of the 2. I know I'm back on my hobby horse but if you search my user name for previous posts you can see my opinions (& data) on why subwoofers disapoint with Klipschorns.

You cannot make accurate plots at these frequencies in the typical home environment the best you do is run prediction software. Here's a good place to start -

http://www.marktaw.com/recording/Acoustics/RoomModeStandingWaveCalcu.html

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Thanks to all of you for your input and ideas. I am constantly learning about this audio hobby. I am pleased to say that my system is darn good right now, with the many changes I have made over the years. From, different tweeters, drivers, horns crossovers etc. The sound is amazing to me. I'm at this point trying to get that last little bit out of the system.

What I am finding out during these more scientific runs is that in my room, in my current setup, the Khorns are performing extremely well in the bass department. Today I once again ran the sub with and without the Khorns, changing the phase to see what results I got. The plot with the the Khorn only was so 'good', that I had to go back and look at old plots of just my khorns. I never really noticed that although there is a rolloff approaching 20 Hz. it is not a very drastic drop. These things perform darn well for a full range speaker.

Below, the red line is the Khorn only, the green line has the sub phase set at 0 and the blue line has the phase set at 180. There is no perfect solution due to room modes and phase changes. I left the phase set a 0. I set my crossover at 40 Hz since the Khorns perform so very well in low frequencies.

post-10337-13819512520566_thumb.jpg

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You cannot make accurate plots at these frequencies in the typical home environment the best you do is run prediction software. Here's a good place to start -

Why do you feel that somewhat accurate measurements can't be made in a home environment? Won't a calibrated mic of reasonable quaility be able to measure what is there, warts and all?

I have used all sorts of room mode calculators since DOS was the latest OS. However, with some decent software, microphone and sound card, you should be able to take some relatively close measurements of what the mic is 'hearing' at a particular part of the room.

Audyssey hardware and software does this exact thing to flatten room response. I can tell you that it works very well.

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Why do you feel that somewhat accurate measurements can't be made in a home environment? Won't a calibrated mic of reasonable quaility be able to measure what is there, warts and all?

I have used all sorts of room mode calculators since DOS was the latest OS. However, with some decent software, microphone and sound card, you should be able to take some relatively close measurements of what the mic is 'hearing' at a particular part of the room.

Audyssey hardware and software does this exact thing to flatten room response. I can tell you that it works very well.

Yes but what the mic is hearing at that point in the room is not going to help with your overall response throughout the room and is not enough of a representation to derive conclusions from. You are making a measurement that is completely dependent on exact frequency & exact location. It does not give a real indication of how the speaker is performing in the room, only how the room is interacting with the speaker at that exact point & time.

The best the Audessy (or any other processor) can do is quesstimate how that reading will translate throughout the listening environment and adjust accordingly. If you happen (for example) to place the measurement mic in a location that, due to room nodes, is 6dB louder at say 60Hz, the Audessy will happily pull that frequency down by 6dB even though 60Hz may be fine at other points in the room.

PJK neatly addressed the bass response problem by placing his speakers in the corners. As the simulation below shows, this is a very easy way to achieve smooth bass response throughout an environment.

Picture1-16.png

Compare this with the room LF response of speakers placed along a wall -

surfaces.png

My HO, through years of doing this for entertainment & a living is that the K's low end work's brilliantly just the way the man designed it. If "boom's" your thing, great, add a sub but don't confuse it with an enhanced or accurate low end.

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I set my crossover at 40 Hz since the Khorns perform so very well in low frequencies.

Good conclusion. Professionally, we almost never allow 2 speaker enclosures to operate in the same frequency band for all the reasons your 1st plot illustrated (that & drivers being cranked into failure becasue the mixer cannot hear the true low due to cancellations). What you have now is a true subwoofer set up (emphasis on sub) where the natural roll off of the K's is complimented by the RSWs.

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Why do you feel that somewhat accurate measurements can't be made in a home environment? Won't a calibrated mic of reasonable quaility be able to measure what is there, warts and all?

I have used all sorts of room mode calculators since DOS was the latest OS. However, with some decent software, microphone and sound card, you should be able to take some relatively close measurements of what the mic is 'hearing' at a particular part of the room.

Audyssey hardware and software does this exact thing to flatten room response. I can tell you that it works very well.

Like I said earlier - Use your Ears and forget the calculators. I'd set the Sub at 30hz and then go LOWER from there.

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phillipbarret: You are correct. The mic can only get readings from one specific point in space. Of course, if the mic is moved, the readings will change due to room modes, high and mid frequency reflections etc. My goal by taking readings is to at least be able to have an idea of the room's interaction with my speakers at the sweet spot. Granted, it is not perfect, but making the attempt is certainly better than not trying to do anything at all to improve perceived response.

I feel that properly treating rooms, primarily in the bass area, goes a long way in helping to achieve a better, smoother sound than not doing anything. All rooms have acoustic problems that affect what we hear regardless of how good speakers and components are. So, any efforts made to reduce the worst effects of room modes and reflections can only help.

I can tell you from personal experience, that my current room sounds a heck of a lot better than the same room with no acoustic treatmetns. Same speakers, same components. Like I said earlier, my efforts now are aimed at getting every last bit of good 'sound' from my system/room environment.

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I have a REL subwoofer and crossover by 'ear' as recommened by REL. It will probably disturb you to hear that my crossover point is 28hz. Too many factors to do it by a calculation. The room being the biggest one. I think most folks have them crossed over way too high and that is why they 'boom'. Most of the time I cannot tell if my sub is even on. It is very subtle and blends well.

I also have REL subwoofer and I did the same thing, although I am using with RF-7s (sadly, no Khorns yet.) I think I have mine around 28hz as well, and noticed just how musically accurate it really is. Seems like it is just a natural extension of the main speakers.

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I feel that properly treating rooms, primarily in the bass area, goes a long way in helping to achieve a better, smoother sound than not doing anything.

Amen Brother! Nothing frustrates me more than folks spending $1,000s on cables, convertors & the like then sticking them in rooms that sound like...er...well not very good.

One hundreth of what you laid out on that stuff spent on some simple DIY acoustic treatment will yield far superior results. Plus, these days there is so much help out there on the web.

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I also have REL subwoofer and I did the same thing, although I am using with RF-7s (sadly, no Khorns yet.) I think I have mine around 28hz as well, and noticed just how musically accurate it really is. Seems like it is just a natural extension of the main speakers.

Same reason, the natural roll off is complimented by the subs. In live sound I tend to cross my subwoofers (generally front loaded 2 x 18s) over at around 60 - 70Hz with an 18dB slope BUT my main cabinets are also high passed at around 120Hz/12dB per octave. Bear in mind these subs have a seperate mix of certain instruments feeding them directly (kik drum, bass guitar, keyboards etc.). This allows me to mix a clean powerfull bass without over-exerting the main system yet the blend between the 2 is pretty seamless.

BTW, all this tuning is done by ear & some favorite songs.

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