As a new owner of the 950/7100 I have found this forum to be very helpful in getting my system set up as it is more difficult (Or more choices/flexibility) than my plug in play HK AVR 300. So, here is another question for all you pros out there.
How do I determine what crossover frequency to use to set up my system. I use no sub and have Klipsch KLF 20 as the L/R mains where I derive my serious bass. The KLFs are reported to be plus/minus 3db from 38-20,000Hz. Do I set at 40,60,80,100.
The reason for my question is that with A/B testing between my old HK and the Outlaws the bass seems to be "tighter" with the HK. This is a big disappointment as the HK was a lot cheaper 3 years ago. I am using the same CD player and CD to test this. So, I guess I am questioning the stereo ability of the Outlaws. The HT portion of the Outlaws is wonderful. By the way, I have tried the bypass in the above tests. Am I missing something in the setup or are the Outlaws just average for stereo. Could it be possible that a $400 receiver could beat the Outlaws in this area?
Thanks to all for helping me out with all my questions. Just seeking musical nirvana.

I would use whatever setting that sounds the best to you - not lacking in bass, not boomy, no obvious peaks or dips in the bass response etc. I would start at 60Hz and see how 80Hz compares. Given the low frequency cutoff of your speakers, one of those frequencies is about right.

As soundhound suggests, I'd try 60Hz and 80Hz and see how both sound. If you have no sub, though, you should make sure the sub is disabled and the mains are set to "large" -- that way, the 950 will ignore the crossover point for the mains and will redirect data from the surrounds and center to the mains.

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gonk -- Saloon Links | Pre/Pro Comparison Chart | 950 Review

Maybe I'm missing something here. His speakers go down to 38 Hz, and the 950 supports a crossover of 40 hz, yet two people have suggested 60 hz or 80 hz? Since he has no sub, doesn't that mean that the 950 will nuke all frequencies below 60 hz or 80 hz respectively?

Unless I'm missing something, I'd suggest that he use a crossover of 40 Hz.

Jeff

I too would not discount the 40Hz setting. When matching up crossover settings with speakers, previously with an ICBM, and now with a 950, I've liked the next crossover point up from the -3dB low frequency cut-off the best.

Soundhound: as a proponent of stereo subs, and since this fellow does not have any sub(s), I would have at least thought that you would have gone for the 40Hz extended "stereo" bass as well? Or am I missing some finer detail here?

Jeff Mackwood

Congrats Soundhound,

You've managed to confound two Jeffs in one thread.

Sanjay




[This message has been edited by sdurani (edited July 13, 2003).]

It's typically best to use a crossover freq that's one octave above the -3 dB point. If the -3 dB point is 38 Hz, that's close to 40 Hz, so one octave up is ... 80 Hz.

Think of it this way: if the -3 dB point is 38 Hz, that means the freq response is already dropping by that point. If you choose a crossover of 40 Hz, you're effectively *adding* the slope of the crossover to the natural roll off of the speakers, and effectively increasing the slope of the crossover. You could end up with a "hole" in the response, and you will get some nasty phase issues as a result. But your ears have to be the judge.

Hmmm. I never knew that!! Are you certain? I mean, -3dB is not an awful lot; barely perceptible, in fact.

Jeff

Also, 80 hz is somewhat localizable. I'd really hate to have a speaker that extends comfortably down to 40 hz still have to relegate the bass to a subwoofer.

I can't imagine crossing my Aerials over at 80 dB! All that lost bass!!

Jeff

Kevin,

I disagree.

Raider has no sub. Less of nothing is still nothing. Better to cross over as low as possible - which would be 40Hz given his speakers' rated -3db point.

Even if he had a sub I'd still start my serious listening / comparing at 40Hz - unless there he's seriously short of amp power or speaker power handling / dynamic capbility, and needs to redirect to the sub to relieve some of the burden.

Sanjay,

At least neither of us is a "Geoff".

Regards.

Jeff Mackwood

Jeff, Are you sure? From everything I've read, 80Hz is a pretty safe choice because frequencies below that point are extremely difficult (if not impossible) to localize.

That said, I think Bob Stuart (of Meridian) claimed that while we can't perceive direction we can sense bass envelopment down to something like 40Hz. By 'envelopment' I mean the mono in-your-head bass vs externalized sounding bass that seems to surround you. This is probably why Lexicon's Bass Enhance processing works on frequencies below 80Hz.

Sanj

Moderately sure. I know that it's been said by many of the cognescenti of the SMR forums in the past. But no, I haven't verified the information myself.

Jeff

Jeff- Actually, with no sub you are quite correct. But if I didn't have a sub, I'd just go full range. That's what people did for years with just plain old "stereo".

Everything I have read (and heard), particularly Dolby and THX info, also says that 80 Hz and below isn't localizeable. In fact, I had a Yamaha receiver for a while with a 90 Hz crossover, and I didn't find a problem with that either. Very specific test tones tests and controlled conditions, maybe, but watching a movie with audio and visual input to the brain, I think that 80 Hz and below is pretty safe. That's why, for example, the official THX crossover setting is 80 Hz.


[This message has been edited by Kevin C Brown (edited July 15, 2003).]

Yes, and it's also why THX has often come under fire for its choice of the 80 hz crossover: many experts claim that it's too localizable and that THX should have chosen a lower crossover point.

Jeff

I think I missed the point that he didn't have subs - my mistake!

Maybe it is just a curse for me, but I can definately sense the pressure direction even below 20Hz (and I'm not just hearing harmonics or room noises). I think some of this is that I have 2 18" subs per side seperated by 22 feet, and they can really move the air with some authority.

Jeff, I think there are relatively few "experts" that claim THX should have chosen a lower crossover point. Bob Stuart, THX, Bose, Dolby, M&K and others have actually put trained ears to the test and found that it is extremely rare for people to be able localize the bottom two octaves. I got a practical demo of this when I visited the facilities of M&K Speakers a few years ago (I used to live near them in Culver City). I'll have to agree with Kevin: 80Hz is a pretty safe crossover point.

Sanj

I thought of a potential bad thing with using a crossover with no sub.

I *think* I remember Bossobass saying that the way that the 950 low passes the LFE channel, is that it applies the same crossover as the mains. So, for example, if you set the 950 up as mains = small, and then no sub, it will effectively eliminate the LFE signal. If you say mains = large and no sub, it will reroute the LFE to the mains. I guess the question would be: potential poor quality bass (distorted) vs no bass, in terms of the LFE channel.

I have the Axiom M80Tis whose Freq Resp is +/-3dB (Hz) 34-22K and +3dB/-9dB (Hz) 25-22K and I cross them over at 80 Hz to my home built Shiva sonosub and it sounds best at this crossover. It's difficult to explain. I don't have the technical lingo. I just trust my ears. At 40 or 60, the bass didn't have that distinct punch, but at 80 there is magic! And my Shiva sonosub rocks. I have it pushed by 400 watts mono. The other 5 speakers are driven by my 770.

"With a 24 dB/octave crossover network a good rule of thumb is to set the crossover point at least 1/2 to 1 octave away from the cutoff frequency of the speaker. Thus a satellite with a cutoff of 5o Hz at the low end that is used with a subwoofer requires a crossover frequency of 75-100 Hz. The subwoofer should then have a range extending 1/2 to 1 octave above the crossover frequency..." Dr. Phil (Marchand)

The variable in HT setups is that the HP is 12 dB/octave to mate with a sealed satellite which has a natural rolloff of 12 dB/octave. The combination sums to a 24 dB/octave slope to mate with the LP of 24 dB/octave applied to the sub.

If your satellites are vented (which have a natural rolloff of 24 dB/octave) the 12 dB/octave HP sums to result in a 36 dB/octave slope, while the LP remains 24 dB/ octave. This means that they do not sum to unity at the crossover point.

Add to this that the 'Q' of the HP is not known nor adjustable and can effect the response of the satellite at crossover, usually by causing a hump or a dip at the crossover point.

Conclusion: Pre-pros should have a selectable slope in the selectable crossover point menu because the majority of satellites are vented. The 'Q' of the HP should be adjustable. Speaker manufacturers should include a recommended HP filter 'Q' value in their specs.

In answering the original question of this thread, I agree with the venerable Gonk. There should be no HP applied to the mains, which should be set to 'large' and sub to 'no' so that the LFE is re-routed to the mains. Adding a HP to the mains causes the rolloff to be much sharper and possibly introduces a damping ('Q') problem at the HP point.

A thought on the 950's bass being less 'tight' than the HK's: I have a 'no dot' version 950 and have always thought the bass to sound very tube-like. Though I almost never listen to stereo CDs, the bass in SACD and movie formats through the 950 is excellent. Given the above posts, some tweaking to optimize your setup's low freqs is no doubt necessary to reach "sonic nirvana", so don't give up...I assure you the 950 will deliver it's part of the equation.

I have a list of "ideal" attributes for a pre/pro. Among the list, is being able to set individual HP and LP frequencies for each speaker, *and* being able to pick the slopes for each as well. Someday maybe!

Hi,

Im also a new user of the 950/7100 combo and Im just begining to try to configure the crossover,etc.

One question:

Bossobass wrote:
"With a 24 dB/octave crossover network a good rule of thumb is to set the crossover point at least 1/2 to 1 octave away from the cutoff frequency of the speaker. Thus a satellite with a cutoff of 5o Hz at the low end that is used with a subwoofer requires a crossover frequency of 75-100 Hz. The subwoofer should then have a range extending 1/2 to 1 octave above the crossover frequency..." Dr. Phil (Marchand)


I have mainspeakers with a cutoff around 40Hz, so following this advice I should set up the 950 crossover at 80Hz, right?
My subwoofer has a variable filter ranging from 40Hz to 160 Hz. Again, following this advice, should I set it up to 160Hz (so its 1 octave above the 950 crossover)???

I know that the ears are the final judge, but just wanted to understand if this is what they are suggesting.

Thanks!
Nestor

I have noticed excellent bass response with High Rez sources while also experiencing somewhat anemic bass with regular CDs. Source resolution and level withstanding, I do not understand why I lose bass impact on CDs at full range settings.

I have powered towers, Boston VR975, (with both speaker and line level connections). I wonder if somehow I am getting a phase cancellation between the speaker level and RCA level inputs. I have never found out just how those speakers are wired. The woofer will run on just speaker level.

I don't feel I have lost definition, just level.

NS:

The quote states that if you select 80Hz (for example), then your sub should have a response to 1/2 to 1 octave above that. In other words, if you select 80 Hz as a crossover point, the low pass and the high pass filters of the crossover are 80 Hz.

The filters are not brick wall. They rolloff at a rate of 24 dB/octave. They overlap the mains and the sub so that there is unity of signal across all frequencies in the overlap region. So, the sub should be capable of response to at least 1/2 octave above 80 Hz, or 120 Hz.

bossobass:

Thanks, so I guess its what I understood...


Mains cutoff around 40Hz, so the 950 crossover should be between 60 and 80 Hz (1/2 - 1 octave above) and the subwoofer should reproduce at least up to 120 Hz (or higher)

Will start my listening tests with 80Hz for the 950 and the subw open up to 160Hz, and trying varations from there...

thanks again!
Nestor

NS: You definitely got it...let us know what x-over point you end up liking the best.