What is the highest crossover frequency for the sub that you can set a pre/pro or receiver before the sub becomes localized or one can hear where the sub is located? Is 120hz too high?

IMHO, yes, 80Hz is reasonable but a lot depends on the arrangement of speakers and listening position.

depends on the whole setup. i've had subs where 80hz was easy to localize but with my current sub i have it crossed at 80hz and it disappears.

If the sub is in the front of the room, between the mains, in most rooms it will be hard or impossible to localize with a 120 hz crossover assuming 4th order cross, and a decent sub that can handle the upper frequencies, and a good setup.

If the sub is far from the mains, say near field behind the listener, it will be easier to locate.

Also keep distortion in mind that while 120 hz is not easily located, if you have stray output at 240 or higher (harmonic distortion) it could easily give the sub away. Same goes for port noise, buzzing, rattles, and any other noises.

I've got my subs sitting just inside the mains and center channel. I have set the xo to 120hz to get more punch in the midbass. I am still waiting to see how I like it.

there should be a thread with a poll on either the 1st or 2nd page here all about crossover settings. check it out.

IMHO, yes, 80Hz is reasonable but a lot depends on the arrangement of speakers and listening position.

Thanks for responding. I have been working so hard that I forgot I made this post.

If the sub is in the front of the room, between the mains, in most rooms it will be hard or impossible to localize with a 120 hz crossover assuming 4th order cross, and a decent sub that can handle the upper frequencies, and a good setup.

If the sub is far from the mains, say near field behind the listener, it will be easier to locate.

Also keep distortion in mind that while 120 hz is not easily located, if you have stray output at 240 or higher (harmonic distortion) it could easily give the sub away. Same goes for port noise, buzzing, rattles, and any other noises.

First, my sub is a Velodyne HGS-18. However, I found out that my center channel is rated from 80Hz to 20,000Hz, but the specs don't say if its plus or minus 3db. However, the specs do rate the center channel at -2db at 120Hz, so I am assuming that I need to crossover the sub at 120Hz in order to keep from losing the frequencies because it may be down -6db at 80Hz. Thats why I was wondering if one could hear the location of the sub at 120Hz.

If the sub is in the front of the room, between the mains, in most rooms it will be hard or impossible to localize with a 120 hz crossover assuming 4th order cross, and a decent sub that can handle the upper frequencies, and a good setup.Or even higher as far as the front and center channels are concerned. But in that location, localization of rerouted surround info is still possible. That said, even with the surrounds crossed that high (or even higher), there is still a lot of info that is shared (or spread) across the surrounds and sub and our ears can often very easily be fooled into non-localizing the sub in this circumstance.

120 with 2 subs maybe, but I think you will hear the difference and feel 80 works better. If you cross at 80, it will still give a wee bit of 100. it will roll off as the mains roll and the sum should be fairly flat when the sub is eq'd in.

i just got an Epik Sentinel. i have it between my left main and center. i have it at 80hz and have no issues at all with localization. especially after messing with the distance measurement and EQing it. it blends right in and sounds very transparent.

120 with 2 subs maybe, but I think you will hear the difference and feel 80 works better. If you cross at 80, it will still give a wee bit of 100. it will roll off as the mains roll and the sum should be fairly flat when the sub is eq'd in.

I can't crossover at 80Hz because my center channel is -2db at 120Hz and -10db at 80Hz. I would loose too much sound from from my center channel at 80Hz. I have determined that my best crossover frequency with my setup is 115Hz hoping that the center channel is only -2.5dbs at that frequency.:D

I can't crossover at 80Hz because my center channel is -2db at 120Hz and -10db at 80Hz. I would loose too much sound from from my center channel at 80Hz. I have determined that my best crossover frequency with my setup is 115Hz hoping that the center channel is only -2.5dbs at that frequency.:D

you established this conclusion from an actual in room frequency response measurement or just based off of the manufacturers specs?

you established this conclusion from an actual in room frequency response measurement or just based off of the manufacturers specs?


In a surround sound setup, you have to set your sub crossover base on the highest lower frequency your speakers will play. (I know I'm saying this wrong) In my setup, while my main front left and right speakers are -3db at 32Hz, my center speakers are -2db at 120Hz and my surrounds are -3db at 90Hz. So, my crossover frequency should be based on the lowest frequency of my center speaker.

In a surround sound setup, you have to set your sub crossover base on the highest lower frequency your speakers will play. (I know I'm saying this wrong) In my setup, while my main front left and right speakers are -3db at 32Hz, my center speakers are -2db at 120Hz and my surrounds are -3db at 90Hz. So, my crossover frequency should be based on the lowest frequency of my center speaker.

you established this conclusion from an actual in room frequency response measurement or just based off of the manufacturers specs?

John

What John H is saying, gbaby, is that your speaker MAY perform better than those specs if your room somehow reinforces the lower frequencies that the speaker produces. Or that the specs may be wrong. Still, for most people, using the published specs as a guide for choosing their crossover settings is probably the most prudent thing to do. And you do seem to have a good grasp of the issues involved, here.

What AVR do you have? Does it have an autoCAL/EQ? If so, you should use it. It will measure your speakers' actual in-room frequency responses and set the crossovers appropriately.

If not, then you will have to go about choosing the crossover setting(s) yourself based upon the information you have at hand. In this case it is the speaker's published specs. If you have the means, you can try to measure the speaker's actual in-room response around its low-end roll-off just to see if you are perhaps getting some reinforcement of those frequencies at and below that point.

You never answered regarding the location of your subwoofer.

What AVR do you have? Does it have an autoCAL/EQ? If so, you should use it. It will measure your speakers' actual in-room frequency responses and set the crossovers appropriately.

I have far less faith in auto configs.

The low end frequency response of most speakers varies with the output level. Just because the speaker can play flat to 80 hz with 75 db test tones does not mean it can with 105 db reference level peaks. Ideally, you want to measure at or near max listening levels.

FWIW, this is why people with good subs may prefer a XO set higher than 80 even if their speakers are rated down to 40. It all comes down to which unit can play the frequency range better, and for a lot of setups the sub can handle the 80-120 midbass range with more output and better quality than the mains/center can. Emphasis on quality, because no auto EQ system on the market can tell which sounds better. I don't believe any of them test FR at reference either, so maybe I should have bolded quantity too.

Manually measure with a tool like REW (DO NOT run 105 db sweeps into the tweeter range if you like your speakers) or use the cheapest yet most effective measurement tool out there...your ears.

One more thing. At the crossover frequency the sub and the mains are each contributing half the sound, in other words each is down -6 db and the signals sum to flat. Above the XO, the sub level keeps dropping off, and the main signal increases. Vice versa on the down side. That means your mains need to keep playing relatively flat (that is what non-THX crossovers are expecting) somewhat below the XO point, and the sub has to play somewhat above.

One more thing. At the crossover frequency the sub and the mains are each contributing half the sound, in other words each is down -6 db and the signals sum to flat. Above the XO, the sub level keeps dropping off, and the main signal increases. Vice versa on the down side. That means your mains need to keep playing relatively flat (that is what non-THX crossovers are expecting) somewhat below the XO point, and the sub has to play somewhat above.

i think each would be -3 at the crossover point, not -6.

Consider that the sub is mono, and reproduces sound that is mostly non directional. Your mains go low enough, yet the centre goes not as low. Do you really want the sub producing bass from the information on the center channel?

Would there be information on the center channel at 100hz that would be "isolated just to the center channel? I would think that at 100hz the information would be a part of the left and right channels too. Meaning if the sub is crossed at 80, and the mains go low, what could possibly come out of the center channel that would need the "help" of the sub.

If the sub is crossed to put information out for the center channel...I bet your sub will become directional and not so hidden.

Do a listening session, and find what works best. There are so many variables at play that going off the specs of that cener channel speaker might not be giving you the effects you want in a 5.1 system.

Your logic works fine for a 2.1 system agreed.

Time to experiment.

i think each would be -3 at the crossover point, not -6.

Second try posting this....

When you double amp power you get a 3 db gain, but when you double drivers or add two sources like sub plus main, you get 6 db.

Here is a "standard" 80 hz crossover with 24 db per octave slopes.

http://www.m-fine.com/80hzxo.jpg


The target level is 78 db and at the XO the sub and mains each contribute 72 db.

What John H is saying, gbaby, is that your speaker MAY perform better than those specs if your room somehow reinforces the lower frequencies that the speaker produces. Or that the specs may be wrong. Still, for most people, using the published specs as a guide for choosing their crossover settings is probably the most prudent thing to do. And you do seem to have a good grasp of the issues involved, here.

What AVR do you have? Does it have an autoCAL/EQ? If so, you should use it. It will measure your speakers' actual in-room frequency responses and set the crossovers appropriately.

If not, then you will have to go about choosing the crossover setting(s) yourself based upon the information you have at hand. In this case it is the speaker's published specs. If you have the means, you can try to measure the speaker's actual in-room response around its low-end roll-off just to see if you are perhaps getting some reinforcement of those frequencies at and below that point.

You never answered regarding the location of your subwoofer.

My pre/pro is an Arcam AV9 and it does not have auto calibration but has crossover frequencies at 5db increments. I don't think I would use it if it did have auto calibration as I think manual is better and more precise. I have no choice but to use the manufacturers speaker specification because the speaker company is reputable (Infinity Compositon Prelude), and I do not have the equipment to measure them myself. But, I can tell you that I honestly feel that I am about 12 years too late in changing the crossover frequency that I normally set at 80 or 90Hz. Now at 115Hz, I can hear sound (I should say frequencies) that heretofore eluded my speakers in surround mode. Now, my center speaker sounds effortless with no strain, and playing DD IIx sounds just as good, if not better than playing 2 channals using the analog inputs of the processor and the analog outs of the source component. My speakers were designed pre THX (which is a bunch of junk anyway) so they (my center and surround speakers) are not THX certified to play using an 80Hz crossover frequency. And, it was just by casual reading that I read my center channel only extended to 120Hz @ -2db. In fact there are two specs to my center channel. One states it is 80Hz to 20,000Hz but down -10db at 80Hz. But the most accurate spec states the center channel is -2db at 120hz which is the reason I used 120Hz as a starting point for the crossover. My speakers have never sounded so good, and somethings I experience transcendental moments while listening.:D Incidentally, my sub is located on a wall about 2 feet in front of my main front speakers. Even at 115Hz crossover frequency, I am still unable to localize the sub and it sounds as if its coming from the front and sometimes on surround programs, the low frequencies sounds like its coming from the rear, and then sometimes it sounds omni-directional.:cool:

My pre/pro is an Arcam AV9 and it does not have auto calibration but has crossover frequencies at 5db increments. I don't think I would use it if it did have auto calibration as I think manual is better and more precise. I have not choice but to use the manufacturers speaker specification because the speaker company is reputable (Infinity Compositon Prelude), and I do not have the equipment to measure them myself. Hmm. You think manual settings are better even though you have no equipment to do any in-room measurements. That is simply illogical.

Hmm. You think manual settings are better even though you have no equipment to do any in-room measurements. That is simply illogical.

I have had Krell pre/pros and a Denon with auto calibrations, and I was not impressed because I could use my Radio Shack calibration meter and get more accurate results. I believe simplicity is best and I do not cater to frills and thrills of the latest generation of equipment. If you notice, the best audiophile oriented equipment have almost no features with some not even having tone controls. Features and gadgets on a pre/pro or receiver are distractions for the uninformed to play with while suffering from inferior designed products. The best way to get a flat response from your room is speaker placement, and room treatment. Sub equilization is better than these auto calibration features. I do own a Velodyne SMS-1, but I took it down once I purchased the Arcam AV9 as I found it unnecessary. This is logic at work.:)

... And you do seem to have a good grasp of the issues involved, here.



Thank you very much. It is certainly reassuring to me. :)

Here is a "standard" 80 hz crossover with 24 db per octave slopes.Unfortunately things are complicated by the fact that the filters in the digital crossover of most AVRs have asymmetric slopes. The low-pass is usually 24dB/ octave but the high-pass is usually 12dB/octave (i.e. THX slopes even when not THX certified or with non-THX modes).

And you do seem to have a good grasp of the issues involved, here.Thank you very much. It is certainly reassuring to me.Well, remember that "too much knowledge is a dangerous thing". Don't overthink this.

I have had Krell pre/pros and a Denon with auto calibrations, and I was not impressed because I could use my Radio Shack calibration meter and get more accurate results. I believe simplicity is best and I do not cater to frills and thrills of the latest generation of equipment. If you notice, the best audiophile oriented equipment have almost no features with some not even having tone controls. Features and gadgets on a pre/pro or receiver are distractions for the uninformed to play with while suffering from inferior designed products. The best way to get a flat response from your room is speaker placement, and room treatment. Sub equilization is better than these auto calibration features. I do own a Velodyne SMS-1, but I took it down once I purchased the Arcam AV9 as I found it unnecessary. This is logic at work.:)I cannot question your preferences but I do question your attributing them to accuracy. BTW, while I do agree that positioning and acoustical treatments are the best way to a flat frequency response, how do you assess the flatness of your response? The RS meter alone cannot do it (even for subEQ) without support of a sophisticated measurement system (such as REW) capable of handling multiple measurement sites and analysis of time issues in addition to FR.

BTW, the "best audiophile equipment" is a very subjective term and that field is dominated by (1) analog equipment and (2) small companies without the resources for keeping at the cutting edge of digital technology. All that is changing, albeit slowly.

Unfortunately things are complicated by the fact that the filters in the digital crossover of most AVRs have asymmetric slopes. The low-pass is usually 24dB/ octave but the high-pass is usually 12dB/octave (i.e. THX slopes even when not THX certified or with non-THX modes).

Well, I put "standard" in quotes for a reason ;) I don't know which receivers behave badly and which don't but I know there is some variation. REW is your friend here.

I don't know which receivers behave badly.............Almost all do. :(

Hmm. That is simply illogical.

I knew it.....Kal Rubinson is just a pseudonym.;)

http://daisydownunder.com/images/M-spockA.jpg

I knew it.....Kal Rubinson is just a pseudonym.;)

http://daisydownunder.com/images/M-spockA.jpgNote the ears. ;)

i just got an Epik Sentinel. i have it between my left main and center. i have it at 80hz and have no issues at all with localization. especially after messing with the distance measurement and EQing it. it blends right in and sounds very transparent.


Wish I could have my sub set for 80hz again. It distorts badly at any setting over 40hz since I hada new driver installed. Sounds good, but not doing it's intended job. Wonder what caused it?

regards,
Red

I cannot question your preferences but I do question your attributing them to accuracy. BTW, while I do agree that positioning and acoustical treatments are the best way to a flat frequency response, how do you assess the flatness of your response? The RS meter alone cannot do it (even for subEQ) without support of a sophisticated measurement system (such as REW) capable of handling multiple measurement sites and analysis of time issues in addition to FR.

BTW, the "best audiophile equipment" is a very subjective term and that field is dominated by (1) analog equipment and (2) small companies without the resources for keeping at the cutting edge of digital technology. All that is changing, albeit slowly.


The bottom line is that my inquiry was whether or not a crossover frequency of 120Hz would make the sub localize, i.e., you can hear the location of the low frequency. In my setup even at 115Hz, I cannot localize the sub. I am not concerned with auto calibration, its accuracy or techniques one can use to make the room flat. I do not and did not want a debate on calibration accuracy of equipment or semantics.

The bottom line is that my inquiry was whether or not a crossover frequency of 120Hz would make the sub localize, i.e., you can hear the location of the low frequency. In my setup even at 115Hz, I cannot localize the sub. I am not concerned with auto calibration, its accuracy or techniques one can use to make the room flat. I do not and did not want a debate on calibration accuracy of equipment or semantics.OK. I was just responding to your post. Over and out.

The bottom line is that my inquiry was whether or not a crossover frequency of 120Hz would make the sub localize, i.e., you can hear the location of the low frequency. In my setup even at 115Hz, I cannot localize the sub.So, if that is the case in your room with your subwoofer placement, why would the additional 5Hz from 115Hz to 120Hz makes a difference?


What is the highest crossover frequency for the sub that you can set a pre/pro or receiver before the sub becomes localized or one can hear where the sub is located? Is 120hz too high?There is no one simple, correct answer to your query. A 120Hz crossover may cause the sub to be localizable in one person's setup but not in another's. What contributes to localization as well as what can help to reduce or mask it has been discussed in the thread. The crossover setting at which a sub becomes localizable depends upon many factors including the location of the sub in the room and its relative location to the other speakers, the treatment and/or acoustic dampening present in the room, the room's FR, etc., etc.. So, it is probably best to answer your own question empirically.

The bottom line is that my inquiry was whether or not a crossover frequency of 120Hz would make the sub localize, i.e., you can hear the location of the low frequency. In my setup even at 115Hz, I cannot localize the sub. I am not concerned with auto calibration, its accuracy or techniques one can use to make the room flat. I do not and did not want a debate on calibration accuracy of equipment or semantics.
It always amazes me whenever I read a thread in which someone asks a question and then argues with the subsequent responders by claiming to have had the answer all along. WTF? Cognitive dissonance, perhaps... (well that and a bad attitude).

OK. I was just responding to your post. Over and out.

We are still alright, though.:)

So, if that is the case in your room with your subwoofer placement, why would the additional 5Hz from 115Hz to 120Hz makes a difference?


I really think that 120Hz is too high and I've never set it that high. The only reason that I chosed 115Hz is that my center channel is rated -2db at 120Hz so I speculated that maybe at 115Hz, it the center speaker is -2.5db.:) I'm really guessing, but the end result is that it sounds damn good in Dolby Digital IIx. In fact I can hear sound that were previously masked in recordings that I am familiar with playing. It is a sound that is not better than 2 channel, but it is different and very pleasant. I am revisiting my music collection now.:D

It always amazes me whenever I read a thread in which someone asks a question and then argues with the subsequent responders by claiming to have had the answer all along. WTF? Cognitive dissonance, perhaps... (well that and a bad attitude).

What?:eek: I think Kal can handle himself.

The reason the other items were discussed is because setup/calibration/integration can make a big difference. They are relevant. If you can not localize 115 you won't localize at 120 either. The wave lenghts are still quite large and a 5 hz step is a small fraction of an octave.

If you can not localize 115 you won't localize at 120 either. The wave lenghts are still quite large and a 5 hz step is a small fraction of an octave.

Thats why I backed it down to 115Hz. I was trying to stay within that +/- 3db range if you know what I mean.

It always amazes me whenever I read a thread in which someone asks a question and then argues with the subsequent responders by claiming to have had the answer all along. WTF? Cognitive dissonance, perhaps... (well that and a bad attitude).I really think that 120Hz is too high.............Thats why I backed it down to 115Hz. I was trying to stay within that +/- 3db range if you know what I mean.I'd put a smiley face but it's not even funny. :(

If you can not localize 115 you won't localize at 120 either. The wave lenghts are still quite large and a 5 hz step is a small fraction of an octave.Hell, it's a TINY fraction of an octave. An octave up from 115Hz is 230Hz.

I'd put a smiley face but it's not even funny. :(

If you revisit this thread, you will see that I was trying to set my crossover frequency to get the maximum sound from my center channel. I normally set the crossover to 80Hz, but my center channel again is -10db @ 80Hz. It is -2db @ 120Hz. My mains are full range, but when you set a crossover frequency for you small speakers (center and surrounds) you need to work within the paremeters of their frequency repsonse. Ideally, your center and surrounds need to be 80Hz to 20kHz +/- 3db. Unfortunately, my center and surrounds don't meet this spec and I can see why Infinity upgraded them to Infinity MTS. These speakers have surrounds that are 80 to plus 20k +/3 db.

It always amazes me whenever I read a thread in which someone asks a question and then argues with the subsequent responders by claiming to have had the answer all along. WTF? Cognitive dissonance, perhaps... (well that and a bad attitude).I really think that 120Hz is too high.............Thats why I backed it down to 115Hz. I was trying to stay within that +/- 3db range if you know what I mean.I'd put a smiley face but it's not even funny. :(If you revisit this thread, you will see that I was trying to set my crossover frequency to get the maximum sound from my center channel. I normally set the crossover to 80Hz, but my center channel again is -10db @ 80Hz. It is -2db @ 120Hz. My mains are full range, but when you set a crossover frequency for you small speakers (center and surrounds) you need to work within the paremeters of their frequency repsonse. Ideally, your center and surrounds need to be 80Hz to 20kHz +/- 3db. Unfortunately, my center and surrounds don't meet this spec and I can see why Infinity upgraded them to Infinity MTS. These speakers have surrounds that are 80 to plus 20k +/3 db.Laugh. :rolleyes:

Here's what I did,,,,

Played around with the settings until I found the one that I liked.

I now have mine crossed over at 100hz and all my bass goes to the sub.

Try a lot, find what you like. Leave it alone.

FYI - if you go below 80hz for LFE you'll loose bottom end for sure.

Laugh. :rolleyes:

What am I missing?:confused: I'm too old to get insulted so be frank.

What am I missing?:confused: I'm too old to get insulted so be frank.You are STILL doing exactly what monomer accused you of doing.

We are still alright, though.:)Sure. I can accept that we disagree.

I have had Krell pre/pros and a Denon with auto calibrations, and I was not impressed because I could use my Radio Shack calibration meter and get more accurate results. I believe simplicity is best and I do not cater to frills and thrills of the latest generation of equipment. If you notice, the best audiophile oriented equipment have almost no features with some not even having tone controls. Features and gadgets on a pre/pro or receiver are distractions for the uninformed to play with while suffering from inferior designed products. The best way to get a flat response from your room is speaker placement, and room treatment. Sub equilization is better than these auto calibration features. I do own a Velodyne SMS-1, but I took it down once I purchased the Arcam AV9 as I found it unnecessary. This is logic at work.:)
It's funny that you lecture the guy who writes for the magazine[Stereophile] and use it's talking points you just repeated here in order to make your point. If you think RS meter is more accurate then the mikes included with the Denon's Audessey then the adjective you used "uninformed" seems to come back and hunt you very quickly. While I would agree that room treatments are great, you would have to hire a professional to do it right, unless you wanna use some computer program with a calibrated mike, to acoustically map the room yourself. Oh yeah the new AS EQ1 from Audessey will run circles around the aging SMS-1. ;)

It's funny that you lecture the guy who writes for the magazine[Stereophile] and use it's talking points you just repeated here in order to make your point. If you think RS meter is more accurate then the mikes included with the Denon's Audessey then the adjective you used "uninformed" seems to come back and hunt you very quickly. While I would agree that room treatments are great, you would have to hire a professional to do it right, unless you wanna use some computer program with a calibrated mike, to acoustically map the room yourself. Oh yeah the new AS EQ1 from Audessey will run circles around the aging SMS-1. ;)

There seems to be some miscommunication, and I will take the blame. Maybe you guys are too smart for me. But, the only thing I use a Radio Shack meter for is to set the level of my speakers to get the correct surround level. Thats it. And, my point with these auto calibration that I've tried in my home is that I got better and more accurate results setting my own levels. Correct me if I'm wrong, but when you set your crossover frequency for your sub in your processor, you have to consider the frequency response of your speakers. In my case my left and right mains are 32Hz to 20kHz +/- 3db. My center channel is 120Hz to 20kHz +/- 3db and my rears are 90Hz to 20kHz +/-3db. So I assume that for surround, you get the crossover correct first and work on the flattening the frequency response second. True or false?:confused: The only reason that I asked initially if 120Hz was too high and could make the sub become localized is that I thought there was some hard and fast rule regarding this and I could get a quick answer that would save me time. I did not change the crossover at the time I made the initial inquiry so I did not know if it was too high, but apparently it is assumed that I did know.

When you double amp power you get a 3 db gain, but when you double drivers or add two sources like sub plus main, you get 6 db.

As a sidebar, the extra 3db you get from doubling the drivers is dependant on those drivers being co-located. Two drivers are generally considered to be co-located when they are within 1/4 wavelength of each other. At 80hz, 1/4 wavelength ≈ 42". At 120hz, that'd be about 28". If your sub isn't close to the speakers it is being crossed with, then the figure ends up being closer to 3db rather than 6.

Also, boundary reinforcement is also dependant on a combination of the frequency and distance to the boundaries. The "direct" sound and reflected sound should be within 1/4 wavelength (for the same reason), so it is often recommended to place subs within 1/8 wavelength of the highest frequency they will produce from wall behind it. The higher you go in crossover frequency, the harder it is to maintain these goals. But the flip side is, the same issues affect the mains, so crossing higher may put that load on a sub which you can place more freely. That's one of the reasons why it's flawed to depend on manufacturer's specs for low frequency performance. How close to walls is their number based on? How closely does your room match their test layout? I have three identical speakers for my LCR. But my system is corner mounted, so the center speaker is much further away from walls than the L & R. Audyssey detects my L & R as "full range", but wants to set the crossover for my center around 100hz, IIRC. Never underestimate the effects of rooms and placement.

There seems to be some miscommunication, and I will take the blame. Maybe you guys are too smart for me. But, the only thing I use a Radio Shack meter for is to set the level of my speakers to get the correct surround level. Thats it. And, my point with these auto calibration that I've tried in my home is that I got better and more accurate results setting my own levels. Correct me if I'm wrong, but when you set your crossover frequency for your sub in your processor, you have to consider the frequency response of your speakers. In my case my left and right mains are 32Hz to 20kHz +/- 3db. My center channel is 120Hz to 20kHz +/- 3db and my rears are 90Hz to 20kHz +/-3db. So I assume that for surround, you get the crossover correct first and work on the flattening the frequency response second. True or false?:confused: The only reason that I asked initially if 120Hz was too high and could make the sub become localized is that I thought there was some hard and fast rule regarding this and I could get a quick answer that would save me time. I did not change the crossover at the time I made the initial inquiry so I did not know if it was too high, but apparently it is assumed that I did know.


IMO, no hard and fast rules as everything is based on the situation. Even if I cross over at 150hz, my sub would be tolerable (Localized though)

You need to set different cross over points and listen to your system for a week or so to decide what you really like.

I would also suggest this, find a cd that has a nice standup or bass guitar track on it. Make sure this bass line crosses multiple octaves. Set your cross over up and listen to how well the speakers and the sub blend as the music moves through the low end range. Find a setting that is pleasing to your ear and then CRANK IT UP!!

Another thing that may be helpful would be playing a simple sine wave sweep, and listen to how the different crossover settings affect the various nulls, localization, and other issues.

I had my crossover at 150 with no localization. This was due to haveing the true subs (dual HSU 3.3's) nearfield behind the seat with a crossover of 50 hz down. Then having HSU MBM-12's (dual next to the mains) at 50 to 180 hz. The subs blended with the mains without any issues. The only thing that I noticed was that the center sounded a little lifeless without the lower bass and I ended up changing the crossover to 100.

Bill

You could also teach your better half on how to set the cross over point. Then have her randomly change the setting for the next month and see what you notice.

As a sidebar, the extra 3db you get from doubling the drivers is dependant on those drivers being co-located. Two drivers are generally considered to be co-located when they are within 1/4 wavelength of each other. At 80hz, 1/4 wavelength ≈ 42". At 120hz, that'd be about 28". If your sub isn't close to the speakers it is being crossed with, then the figure ends up being closer to 3db rather than 6.

Also, boundary reinforcement is also dependant on a combination of the frequency and distance to the boundaries. The "direct" sound and reflected sound should be within 1/4 wavelength (for the same reason), so it is often recommended to place subs within 1/8 wavelength of the highest frequency they will produce from wall behind it. The higher you go in crossover frequency, the harder it is to maintain these goals. But the flip side is, the same issues affect the mains, so crossing higher may put that load on a sub which you can place more freely. That's one of the reasons why it's flawed to depend on manufacturer's specs for low frequency performance. How close to walls is their number based on? How closely does your room match their test layout? I have three identical speakers for my LCR. But my system is corner mounted, so the center speaker is much further away from walls than the L & R. Audyssey detects my L & R as "full range", but wants to set the crossover for my center around 100hz, IIRC. Never underestimate the effects of rooms and placement.


I'll admit to being a little lost. I thought that if a speaker was rated for example 90Hz to 20kHz +/3db that the +/- 3db was referring to the fact that the frequency would be either up or down 3db at either the low end (90Hz) or the high end (20kHz).:confused:

I thought the if a speaker was rated for example 90Hz to 20kHz +/3db that the +/- 3db was referring to the fact that the frequency would be either up or down 3db at either the low end (90Hz) or the high end (20kHz).:confused:
What that is supposed to communicate is that between that range, the response will not vary more than 6db from the highest peak to the deepest valley. That doesn't necessarily mean that the extremes will be at the ends of the range they are measured. But even IF the manufacturer has honestly reported the response, that still doesn't tell you HOW that response was measured. Generally speaking, as wavelengths become large relative to the size of the drivers, and even the baffles they are mounted in, their output becomes less and less directional. Speaker manufacturers will even boost low end output of their speakers to compensate for the fact that much of the lower frequency output "leaks" to the sides and rear of the speaker, relative to the higher frequencies. If you take x amount of energy and focus the output in a cone out the front of the speaker at 20khz, that same amount of energy radiating in a sphere at 90hz is going to result in much less relative output directly in front, but more in other directions. But not all that lower frequency output in other directions is necessarily lost.. some of it can be recovered in boundary gain depending on the orientation and distance to nearby walls. So a given speakers performance is going to vary greatly depending on the room and orientation in that room, particularly in the lower frequencies.

You speakers might produce 90-20000hz +/- 3db in their measurement chamber. What they do in your room, in the specific positions in your room, is an unknown until you measure it. And as suggested much earlier in the thread, even once you know the response at a given output, that doesn't take in to account things like headroom, distortion, etc. There are a LOT of variables, and testing is the only way to figure out what works best. But basing a crossover point on manufacturer's published response curves is better than choosing a crossover point randomly with your eyes closed.

... But basing a crossover point on manufacturer's published response curves is better than choosing a crossover point randomly with your eyes closed.

I guess this is where I am at the moment. Thanks for your response. :cool: