what is crossover?

[admin_exported]

Can someone explain in a cat sat on the mat style what crossover is?

It sounds like its something to do with speakers and subwoofers. But maybe I'm wrong?

Pardon my ignorance but you guys are so helpful.

I must admit since i plugged in my sub a few years ago I havent a clue what half the settings do and apart from telling my (soon to be dissapearing) amp that I have a amp connected and to send the LFE frequency to both the main speakers and the sub I've done nothing else.

Ignorant of Barnsley.

 

[Big Chris]

A crossover is a little box of electronic components which filters off certain frequencies (Coils for low frequency & Capacitors for High frequency...... Or could be the other way round)

So a stereo speaker will have a crossover to send only high frequencies to the tweeter, and mid/low frequencies to the woofer.

A sub usually has a dial for adjustment of the crossover, allowing you to dictate how much of your soundtrack it's dealing with. The higher the number (eg 150hz as opposed to 80hz) the further into the upper bass/lower mid region your sub will be playing.

A sub partnered with smaller speakers (such as my MT-30 system) will have to be set to play slightly higher up the frequency range, as the smaller speakers will tend to 'roll off' earlier.

If you have large speakers for your front pair, you won't need the sub to be playing as far up the frequency range.

I can go into slopes if required.

 

[Anonymous]

Main hifi speakers are designed to transmit most of the frequency spectrum that we hear, which satisfies most of the CD or movie soundtrack you listen to.

But very low bass may be beyond the capability of such speakers. A sub woofer, being a purpose built speaker, can reproduce lower bass sounds than conventional speakers.

The crossover is the point at which the main speakers 'run out of puff' producing the bass, and the subwoofer takes over.

For example: if your main speakers go as low as 70Hz, then you will set the crossover point on your AV amp at 70Hz. This means that any part of the audio signal below 70 Hz is re-directed to the subwoofer. So your main speakers reproduce everything 70hz or above and the sub is reproducing everything below 70Hz down to the lowest limit of the sub.

In theory this set up produces even more of the total audio spectrum - especially bass which requires a lot of power because more air needs to be moved; hence the large cones in the design.

If you have an AV amp in which you set up the sub crossover (also called LFE crossover) then the sub's own crossover setting on the back is by-passed (ignored).

If you wanted to set up a sub with main stereo speakers with a conventional stereo amp, you will use speaker wire connections to the sub and you will have to then set the sub's own crossover at 70 Hz or whatever, as hifi amps don't have crossover configuration built in.

Hope this helps!

 

[Anonymous]

Big Chris & Shreddy - Thank you very much for that.

Can i clarify

My next step is to find out how low my main speakers go, find the setting in the home cinema amp to ensure it sends the lfe signal lower than this to the sub. A very quick search on google tells me the speaker delivers a "frequency response" of betwen 45hz and 22 hz, So I set it to 22?

My sub has a "frequency response" knob which goes between 35hz and 200hz,

Does this mean my main speakers can handle a lower bass signal than my sub? (22 is less than 35)

That cant be right surely?

Thank you & sorry if i'm not following

 

[Andrew Everard]

No, your speakers will do 45Hz - 22kHz. So you should theoretically set the crossover to 50Hz, but then speaker bass response figures tend to be both optimistic and measured in a flattering fashion, so I'd suggest a setting of around 60Hz would be more on the money.

 

[Anonymous]

The lowest frequency is always stated first, as Andrew points out.

You will not need to set the crossover dial on the sub itself - some people say you set it to max in case it is not bypassed as I mentioned earlier. You will set the suggested 60 Hz on your home cinema amp (Yamaha).

Another thing to bear in mind is that you may not want to ask your main speakers to go as low as they can since the sub is a 'bass specialist'. So taking some of the audio strain off the main speakers can imrpove the overall sound, hence Andrew's suggestion of 60Hz is a good starting point.

 

[beater]

I have set my system up using the amp set-up mic, when i went into speaker configuration on my amp it had set my speakers as follows: (do they look about right?)

sub yes / fronts 150hz / centre 80hz / surround 60hz / surr back 150hz / surr back ch 2ch / lpf of lfe 80hz.

panasonic 50px70 / panasonic bd30 / panasonic ex87 / onkyo 606 / kef iQ5se's / kef iQ2c / kef iQ1's on atacama stands / 1005's for back surrounds / bk xls200 mk2 sub.

 

[Anonymous]

Ideally your two fronts and centre should match in terms of crossover whereas yours are very uneven. Also the fronts and centre tend to be the largest speakers with the greatest frequency range as they handle most of the movie soundtrack.

Yet your surrounds seem to be outputting the lowest bass!

I would consider swapping your surrounds with your front stereo pair if these figures are anything to go by.

Your LFE (sub) seems to have been set to match the centre at 80hz, but it might be better to match them with your fronts.

In summary, these are strange, unbalanced settings and some swapping of speakers might yield better results.

What does it sound like?

 

[beater]

Thanks for the reply shreddy, i think it sounds quite good, but as you have said they are very uneven, don't quite get how you are telling me to set my speakers up, is it something like this.

fronts 60hz / centre 60hz / surrrounds 150hz / surr backs 150hz / lfe 60hz.

 

[Anonymous]

Hi beater.

Your auto set up has set these, but they do not always do a decent job and this might be worth tinkering with.

Can you tell me exactly which speakers you have?

I set mine up using the auto set up but I had already previously configured them using a soundmeter, a laser distance measure and a test disc. My settings were nothing like the auto ones and the auto function sounded bloody awful.

I can suggest some settings and you can at least restore them to your original settings if you don't like it

Your amp should tell you how loud it has set each speaker (in db); can you post them too?

 

[beater]

Hi shreddy.

My speakers are kef iQ5se's / kef iQ2c / kef iQ1's for surrounds / kef 1005's for back surrounds and a bk xls200 mk2 sub all run by a onkyo 606 amp.

I set mine up with the auto set-up as well, then i used a sound meter for speaker levels and a tape measure for distance.

 

[Anonymous]

Chris, Shreddy & Andrew. ÿThank you all once again.

I thought that if the number was low then the bass was low, then I re-read all your posts and it all makes sense now.

Amp re-set and sounding good. While doing I noticed i had the rear speakers set to small. ÿI changed it to large and I now get a much better sound field.

I'll have it all to do again if my LX81 ever arrives.ÿ

 

[Big Chris]

Glad it's working out Dave.

 

[Big Aura]

useful thread.

I my fronts go to (as I recall) 49hz and rears to 55hz. I have set the amp to cross over at 60 all around (the alternative is 40, there's nothing inbetween). I've set the sub to come in at 80. And set it up as LFE only (rather than LFE + Main). Anyone think that's wrong?

Do I need to fiddle with the knobs on my sub - presume the sub will deal with whatever is thrown its way, if the amp is set like that?

Cheers

 

[Big Chris]

I know with my sub, the crossover dial is only used with the high level/speaker inputs. When using the phono/RCA input, the sub crossover is bypassed. The receiver dictates the frequency.
Different subs may well (and probably do) function differently though.

B.A. If your surrounds are rolling off at 60hz, sub at 80hz seems sensible with the small overlap. You could roll the surrounds off at 80, but as they're a decent size, it makes sense to get as much meat out of them as possible. I'd stick with what you have.

 

[Tom Moreno]

shreddy:
Ideally your two fronts and centre should match in terms of crossover whereas yours are very uneven. Also the fronts and centre tend to be the largest speakers with the greatest frequency range as they handle most of the movie soundtrack.

Yet your surrounds seem to be outputting the lowest bass!

I would consider swapping your surrounds with your front stereo pair if these figures are anything to go by.

Your LFE (sub) seems to have been set to match the centre at 80hz, but it might be better to match them with your fronts.

In summary, these are strange, unbalanced settings and some swapping of speakers might yield better results.

What does it sound like?

Shreddy,

One thing to note is that the Auto Calibration takes measurements of the speakers in the room, Beater's system as being measured probably is more to do with placement of the speakers in the room. I would venture to guess that the fronts are out and away from the wall in order to allow them to breath and that the surrounds might be close to the wall producing an enhanced bass via proximity effect. Beater what kind of split would you say your listening habits are Music/Movies wise? If you, as am I, are a more predominantly movies man, I would suggest using the THX standard crossover of all channels at 80 Hz. If your speakers are properly calibrated then this should provide even bass and good low end extension while allowing you to hear the film as it was mixed and as the cinemas that screen it are set up as well. You'll find that some Disney films that were mixed on the in-house stages in Burbank aren't actually mixed in 5.1 but 5.0. This is because for quite a while the sound services department had an ethos that all systems that are correctly set up are crossed over at 80Hz anyway so any information below that frequency would be correctly routed to the sub in that fashion.

Obviously if you have smaller lifestyle type speakers the crossover will inherently need to be set higher but in general film sounds the most authentic and accurate (and this what we are usually striving for isn't it?) when all channels are crossed over at 80Hz.

 

[beater]

Hi Tom Moreno, i watch movies 95% of the time so i will give your suggestion a go to see how it sounds.

 

[Anonymous]

Hi Tom Moreno and yes you are right in pointing out the calibration is picking up perhaps room interaction and the frequencies posted are not necessarily the limitations of the speakers.

Since I did not know what the speakers were, I though that maybe the rears had a greater frequency range than the fronts, but I suspect your speculation is right.

Anyway, it sounds good apparently, and that's what matters.

There is no harm in manually trying to match the sub a little more with fronts to see; perhaps with some lowering of the front db levels and dropping the crossover of these?

 

[Anonymous]

Hi Beater.

You may well know these figures but here we go:

your speakers have these bass frequency limits

Fronts (iQ5SE) 40 hz Centre (iQ2c) 70 Hz Surrounds (iQ1) 50 Hz Surr Rears (1005) 120 hz

Apart from the 1005's , the above were sold as a home cinema package by KEF and therefore well matched in terms of voicing and frequencies.

Tom's other advice regarding starting with 80 Hz as the crossover is 'sound' (forgive the pun!) since this is the THX standard and all of your main speakers will cope. You will then need to sit with your sound meter and adjust the db level of each speaker. If your main fronts seem too boomy, then you may be getting too much overlap from the sub, the fronts and the room i.e. the frequencies which the room emphasises more than others.

You will need to 'live' with the settings for a while before evaluating so you can test different soundtracks - unless you have a test disc with a frequency tone sweep. You can then maybe pick up on which part of your system keeps being noticably emphasised.

And if you preferred it the way it was - restore your settings.

I'm sorry I can't offer any more help and your system may be just fine. Happy listening!

P.S. I also have the Onkyo 606 and Sony SS-L speakers + REL Strata II sub. The auto set up was awful - too boomy and the rears were set too high. I listen to 75% movies 25% 5.1 music SACD's and DVD-A 's.

 

[beater]

Thanks for your time and all your advice guys, I've taken on board what you've said and set the fronts, centre, sub and surrounds at 80Hz whilst leaving the back surrounds on 120Hz. I shall watch a few movies ( fitting round the wife and kids!) and see how it sounds.