what hertz should i start with for RSW-15 with RF-7's?

[Klipsch RF7]

Hi Guys,

What hertz frequency should I set a RSW-15 subwoofer, they are going with my RF-7's which are my mains. What do you guys set the subwoofer to?

[KiNNi C P]

i believe that the RF7 hit down to the low 30s. I would set the sub to handle everything below the 40's, or maybe the 50s, and run the RF7 as large for music listening.

For movies, i will cut off the RF7 at 50-60, and let the sub handle everything below the 80s for movies, but becareful with the placement, make sure that none of the bass cancels out.

[nicholtl]

THX recommends setting the crossover frequency at 80hz, but I like to keep the cutoff at 100hz. Allows for the sub to play more "musically," in my opinion. Everyone has a different flavor...some go as high as 120hz.

Quick question - does your receiver/preamp have an electronic cutoff frequency option? If so, you are going to want to utilize THAT instead of your RSW-15's cutoff switch. Granted, the RF-7's hit down to the mid-40's, but that doesn't mean they necessarily should. Especially since you own a fine sub...might as well let your sub handle the LFE duty, which is solely what it was designed for. Furthermore, setting the sub between 80hz-120hz relieves a lion's share of the stress placed on your amplifiers (the ones driving your RF-7's), and some even contend that it allows for the RF-7's to play clearer and smoother, as they are not having to struggle as much.

After setting your desired LFE crossover via your receiver/preamp, bring the frequency all the way up on the RSW-15. Because the crossover somewhat 'blends" in with where your mains will leave off, as opposed to cutting it off sharply like a butcher knife, you're going to want to allow as much headroom as possible for the mix, so as to not allow for any hollow spots in the LFE spectrum.

[Klipsch RF7]

Well, my current stereo system consists of mono bloc tube amps with a tube preamp, the tube preamp just has volume and input selector. It has 2 sets of main outputs, I have the amps going to one of the outputs and there is another set of left and right outputs that i will run to the subwoofer. I listen to 2 channel music 90% of the time and would like to add more bass and slam to my music CD's. So, I am going to want to set the sub to 80hz to start with correct? and have the Lowpass filter set to on?

[nicholtl]

Just a heads up - next time it would have helped if you stated your setup from the get-go.

Why not just start from the very lowest hz frequency on your sub, sit back and listen, and then proceed to up it in 10hz intervals until you find one to your liking?

[Klipsch RF7]

That is not a bad idea at all NicholT, That is what i will do then. I will start from the bottom and work my way up and find the sweet spot!

[Frzninvt]

While the RF-7's can go low I have found like Nicholtl stated that most DVD soundtrack's are mixed at the 80Hz THX standard and I do lose some output setting the subs at 60Hz vs. 80Hz. I leave them at 60Hz however since they can generate substantial bass even at that frequency. I set the mains to "Large" why because they are! In addition, my NAD has a special option that compensates if so desired when all speakers are set to "Large" unlike most receivers.

Since you are mostly a music listener alot of the above is a moot point, I think the 10Hz increments until it meets your liking is the way to go.

[MrMcGoo]

The best frequency to cross over to the subwoofer is a fucntion of:

1. Whether or not there is a global crossover, or a different crossover is available for center and each pair of channels.

2. The settings available on the processor or receiver.

3. The power output capability of the amp or receiver.

4. Personal prefernces.

5. Room acoustics and subwoofer location.

6. Use of a BFD or similar equalizer.

Persoanlly, I set all speakers to small and and set my global crossover at 80 Hz due to the bass limits of the other Reference speakers. Speakers should be capable of good output one full octave below the crossover point so that the speakers can blend with the subwoofer.

Bill

[Deang]

There are two ways you can go, and I've had success with both. Which works best will be determined by the placement of the RF-7s, and how bass behaves in your room.

1) Use both main outs on the preamp. One set goes to the Dynacos to push the RF-7s full range, the other set goes to the sub. Set the sub's crossover to 40Hz (the knob controls the low pass filter). Try to get the RF-7s at least a foot or more away from the walls or corners. The magic number for me was about 18". Turn the sub all the way down, and put on something with some good bass. Slowly bring up the volume on the sub until you just begin to hear the bass come in -- stop -- that's where you want it. Now do some listening and start tweaking. You will end up juggling between 40Hz and 50Hz, and with the volume.

2) Only use one set of main outs on your preamp: Run a set of interconnects from the preamp to the sub's low level inputs (left and right, RCAs), and then use another set of interconnects to run from the low level outputs on sub, back to the amplifiers (left and right). Now you are making use of the sub's high pass filter. You are sending the full signal to the sub, and letting the sub's crossover split the signal. On all of the subs I have seen, this filter is not adjustable, and is preset. I'm only guessing, but Klipsch probably used either 60Hz or 80Hz. I have no idea what the slope would be. Most subs are 6db/octave, and there is quite a bit overlap between the sub and the mains.

#1 involves more tweaking (much more), but once you get it dialed in -- it's absolute bliss. In two cases, it took me almost a week to get it "right". The advantage with doing it this way is that you are not running the full range signal through the high pass filter first, before it gets to your amps -- and the sound tends to be much cleaner through the high frequencies. So, if you like to listen at high volumes, there will be less to set the ears off. This method isn't true biamping, you are simply using the sub to reinforce, and extend the bottom -- which is more times than not what I ended up doing.

#2 is much more straight forward, and placement issues with the RF-7s won't be near as critical. Using the sub's high pass filter means the RF-7s are alleviated from reproducing most of the bass, and generally speaking, it's much easier to get good integration between the mains and the sub. This method is also "true biamping", since the signal is "split" between the sub and the mains. Another plus is that since the woofers of the RF-7s aren't doing much bass anymore -- they will do a better job at reproducing the critical midrange. There is both less intermodulation and harmonic distortion -- and it's very easy to hear at higher volumes.

Something to consider in your decision is the fact that you run tube amps, and sending a partial signal (nothing below 80Hz) to the Dynacos, changes the behavior of the amplifiers. They weren't designed to run this way. OTOH, everyone does it -- so WTF do I know.

I say since you aren't pushing the RF-7s in a huge room with 200wpc, work #1 the best you can. The highs will be cleaner, the Dynacos will be happier, and you'll have great bass too -- but you have to work it.

[Klipsch RF7]

Dean,

Thanks for the detailed write up! very well done, i have the subwoofed placed right next to the right channel RF-7, it is about a foot away on the left side of the speaker towards the back, the RF-7s are 2 feet off the back wall and less than a foot from the side walls. I am running method #1, sub going to main outs and amps on the other set of Main outs on the preamp. The sub is set to 50hz on the dial and so far it sounds pretty well blended, ill keep playing with it and tweak it here and there, but it has filled the bottom end void indeed!

Thanks!

[colterphoto1]

" Why not just start from the very lowest hz frequency on your sub, sit back and listen, and then proceed to up it in 10hz intervals until you find one to your liking?"

Excellent advice, just keep sneakig it up (with a variety of source material) until it starts sounding 'honky' or 'tubby'. Remember to play with placement as well. Then back off a little, and make sure you overlap your crossover points with full-range system a bit. I might advise staying away from the 120Hz as a xover point, there is a ton of information right around there, it is fairly common for engineers to put a 'bump' here so a little kick drum slap is heard on even the cheapest of radios and car systems.

Remember that it's a logarithmic scale, so 20-40 is an octave, 40-80 is an octave, etc. so don't expect too much mid-bass and transient response out of a heavy 15" woofer. I tend to let the full range speakers take as much as they can without overextending them. Remember RF7 is a pretty big 3-way system that can move lots of air on it's own.

Agree with using slightly diff theories for HT vs 2ch setups. Good thread!

[colterphoto1]

clarification, I know the RSW15 is ceremetallic cone so is light with good transient attack, but I meant relative to the other drivers in main system. Klipsch specs show RSW15 good to 120Hz +/- 3 dB so I wouldn't ask it to xover above 80 Hz or so. Remember the crossover point is the BEGINNING of the low pass curve, depending on your electronics, it's still putting out say -6 or -12 one octave up, -12 or -24 two octaves up, it's not a very sharp cutoff on most systems. Same goes for Hi-pass filter network for full-range system. The overlap area is critical.

[cjgeraci]

RF7:

On a some songs, I still run without subs in two-channel. However, I have begun incorporating the subs more and more back into my musical mix. I currently have my setup similar to Dean's #1 scenario. My Peach does not have two sets of main outputs. Notwithstanding, I split one of the main outputs, sending one signal to my SVS PB2-ISD. I have played around with it and have also found 50hz to be an ideal cutoff on my SVS for the RF-7s. Early on, I tried limiting the bass frequencies going to my RF-7s. I know, less distortion, strain, etc. However, with both of my preamps (tube and SS), the sound is so much fuller when feeding them full bass response, that is where it will stay. Since you have the amps to give them the nice stuff, I would continue to run them that way. Again, it really depends on what amps people run with these RF-7s, and you have that well-covered. Glad to hear you got them back after the mods.

I run my HSU sub for the SS preamp. My Classe pre/amp handles the SACD/DVD-Audio duties (and some small amt of redbook), and its does the crossover work for my HSU VTF-2. I have the Classe crossed over at 60HZ for the HSU only because I get somewhat of a slightly thinner-sounding bass response with SS (vs. the tube pre-amp). This also accounts for the difference in assigning which sub to which preamp (SVS vs. HSU- different sounding bass).

Completely different settings for HT. Set at 80hz for movies.

Carl.