sholling

sholling

Audioholic Ninja
I've been shopping subwoofers and talking to several manufacturers and one (who will remain nameless) came back with a statement that threw me. His claim is that no receiver actually has multiple crossover points. He claims when I set the crossover point for my mains at say 40hz and the crossover point for my surrounds at say 80hz that the receiver only uses the lower (40hz) figure for the crossover. That the separate crossover points for other speakers are merely a low pass filter (in this case 80hz) for the surrounds and center so that they don't receive any signal too low for them to play. But he says the sub is not covering the lows for the surrounds. That the crossover only covers the lows for all 5 or 7 speakers if they are all set the same. This goes against everything that I've read and heard. Thoughts?

I'm using an Onkyo TX-NR906 but he claims that this goes for any receiver.
 
j_garcia

j_garcia

Audioholic Jedi
I had never heard that, but would be very curious to hear if someone could confirm this. Fortunately all my speakers are the same so I use one x-over.
 
TLS Guy

TLS Guy

Seriously, I have no life.
I had never heard that, but would be very curious to hear if someone could confirm this. Fortunately all my speakers are the same so I use one x-over.
I don't see how you could engineer it any other way.

Actually the other speakers will be a high pass crossover.

So if you set the mains to 40 Hz, and sub to 40 Hz that will be the crossover. Any other speakers set above that will play down to the the point of crossover, and then there will be a gap to the sub. However the trade off I suspect in practice is not that great as long as there is no gap with the mains.

Basically the best solution if you are not using full range speakers is to set the crossover point at the point of the speakers that require the highest crossover.

This is another reason why I believe if possible all speakers should be highly capable.

On Blue Ray disc I notice a lot more power put to the surround and back speakers.

One movie my grandson brought down, was Men in Black. The kids just loved it on this rig and all speakers got an a good work out. Sound effects were just great fun and the grandchildren had to watch it through twice!

By the way that is a movie that kids seem to really enjoy.
 
sholling

sholling

Audioholic Ninja
I don't see how you could engineer it any other way.
Yes back when crossovers were a simple circuit, but these days with modern digital processing it wouldn't be difficult at all. It's all just bits until it leaves the preamp section. It's a simple matter of writing an algorithm to apportion the signal to the sub. It might be a couple of dollars more expensive than a dumb variable filter (also digital) as described by the subwoofer guy but not much.

Actually the other speakers will be a high pass crossover.
A high pass for the sub and a low pass for the surround speakers

So if you set the mains to 40 Hz, and sub to 40 Hz that will be the crossover. Any other speakers set above that will play down to the the point of crossover, and then there will be a gap to the sub.
That would sure get me riled up at the manufacturer.

Basically the best solution if you are not using full range speakers is to set the crossover point at the point of the speakers that require the highest crossover.

This is another reason why I believe if possible all speakers should be highly capable.
I fully agree with you. It's a big part of why I ruled out Axiom's M22 and companion pieces when I was looking at speakers for my bedroom. Besides not wanting rear bass ports I did not want a system with a center and surrounds that would have to be crossed over at 100hz. Instead I'll be going with 5 identical speakers.
 
Y

yepimonfire

Audioholic Samurai
i don't see any reason why that's not possible and i also don't see why a mfg. would do that seeing as it is a bad idea. all processing is done by a computer in the receiver, it can do anything it is designed to do, i can set my fronts to 80hz x-over and my surrounds to no x-over and only get the x-over on the fronts, the surrounds will remain full range. i can do this with any combination of speakers i want. i once was crossing over my center and surrounds into the fronts with no issues at all. the possibilities digitally are endless, there is absolutely no reason why each channel cannot be individually processed. this discussion can be ended by playing multi-channel music and playing with the x-over points and observing what happens.
 
Y

yepimonfire

Audioholic Samurai
also, forgot to add, i always cross over all my speaker at 80hz, even if they are bass capable because of the benefits this has, first off, with bookshelf speakers, even though they can extend down to 55hz, let's face it, 5.25 inch woofers are nothing more then good mid-range and mid-bass drivers, they are not able to cleanly reproduce bass frequencies let alone sub-bass frequencies (below 40hz). they just sound much more open and clear with that high x-over point rather then forced with a lower one, and, your saving amp power and giving yourself more headroom. secondly, with larger three-way speakers, you are in essence creating a four way system loosely following the 3 octave rule with the woofers covering only the mid-bass sections and the sub handling the lower bass section. it just sounds better to me.
 
sholling

sholling

Audioholic Ninja
I'm not convinced that the gentleman was correct. It's a great way for an electronics manufacturer to alienate customers if word got out. But I have no information. Fortunately everything in my family room will comfortably play down to 60hz (40hz for my mains). I just prefer to have the mains handle music as low as possible.

Everything in my office crosses over at 80hz and my master bedroom system when finished will all be set for 70hz.
 
TLS Guy

TLS Guy

Seriously, I have no life.
Yes back when crossovers were a simple circuit, but these days with modern digital processing it wouldn't be difficult at all. It's all just bits until it leaves the preamp section. It's a simple matter of writing an algorithm to apportion the signal to the sub. It might be a couple of dollars more expensive than a dumb variable filter (also digital) as described by the subwoofer guy but not much.
The crossovers are analog after the DAC. There are IIR digital filters that are approximations of analog filters, but not as good and the same rules apply. The there are finite infinite response filters, that require a huge amount of processing power. They have linear phase response but huge delay, which would be problematic in a receiver. A full digital FIR crossover with delay correction would probably increase the cost of a receiver at least ten fold, may be more. I doubt you wold be able to put amps in the same case for heat reasons

There are very few FIR filters around.

The crossover in all HT gear I'm aware of are electronic analog filters. That is why the highest order is fourth and usually on the low pass crossover, the high pass filter is generally second order.
 
j_garcia

j_garcia

Audioholic Jedi
I have seen it on the Harman Kardon receivers. You can set different x-over poitns for types of speakers (mains, surround, etc...) based on their capabilities. It is tough to detect a gap, but I suppose that if it is using the lowest point for the low pass to the sub and whatever setting you chose for the surrounds, there would be a gap there. For example, if you had mains good to 30Hz, you could cross them at say 60Hz. Surrounds that are good to ~50 crossed at 80. If what is being said here is correct, everything will be fine for the mains but there will be a gap in the lower midrange for the surrounds. I don't see why it would be difficult to implement, but I do see that the processing to handle it would go up quite a bit, so I am curious how HK has done this since they offer this capability.
 
TLS Guy

TLS Guy

Seriously, I have no life.
I have seen it on the Harman Kardon receivers. You can set different x-over poitns for types of speakers (mains, surround, etc...) based on their capabilities. It is tough to detect a gap, but I suppose that if it is using the lowest point for the low pass to the sub and whatever setting you chose for the surrounds, there would be a gap there. For example, if you had mains good to 30Hz, you could cross them at say 60Hz. Surrounds that are good to ~50 crossed at 80. If what is being said here is correct, everything will be fine for the mains but there will be a gap in the lower midrange for the surrounds. I don't see why it would be difficult to implement, but I do see that the processing to handle it would go up quite a bit, so I am curious how HK has done this since they offer this capability.
There is no problem having different high pass crossover points as they are going to individual amps.

However the LFE is one output, and in the analog solution you have to thoroughly buffer the different crossovers if you are going to combine them. That is complex and expensive.

I have a the upper 10" drivers in my mains driven by an amp fed from two active crossovers. It is not easy to implement.

At the price range of receivers such implementation would be prohibitive.

The leader in digital crossovers is this outfit. At the current time their technology is expensive, and I don't believe a receiver manufacturer has yet taken out an license or included OEM product.
 
darien87

darien87

Audioholic Spartan
My Emotiva UMC-1 is supposed to have this feature, and that is actually one of the reasons I bought it. But I do indeed have my subs crossed over at 80hz, the same as my rears because I didn't want there to be a gap. My mains are crossed over at 40hz and the center at 65hz.
 
TLS Guy

TLS Guy

Seriously, I have no life.
My Emotiva UMC-1 is supposed to have this feature, and that is actually one of the reasons I bought it. But I do indeed have my subs crossed over at 80hz, the same as my rears because I didn't want there to be a gap. My mains are crossed over at 40hz and the center at 65hz.
That probably is your best solution. It is always good to keep in mind that you can use crossover gaps to your advantage to smooth in room response. Sometimes you can use overlap to advantage to smooth nulls. It is always worth the time to experiment.

Everything is now geared the way it is with sealer sub combinations. Truly integrated speaker systems for HT are complex and costly to engineer. As you know I have done. The results are truly worth the time expense and effort.
 
M Code

M Code

Audioholic General
I've been shopping subwoofers and talking to several manufacturers and one (who will remain nameless) came back with a statement that threw me. His claim is that no receiver actually has multiple crossover points. He claims when I set the crossover point for my mains at say 40hz and the crossover point for my surrounds at say 80hz that the receiver only uses the lower (40hz) figure for the crossover. That the separate crossover points for other speakers are merely a low pass filter (in this case 80hz) for the surrounds and center so that they don't receive any signal too low for them to play. But he says the sub is not covering the lows for the surrounds. That the crossover only covers the lows for all 5 or 7 speakers if they are all set the same. This goes against everything that I've read and heard. Thoughts?

I'm using an Onkyo TX-NR906 but he claims that this goes for any receiver.
For inexpensive AVRs , often only a single X-over is available and is global applied to all loudspeakers set to Small..

But in name brand AVRs selling for >$399 they typically have the capability to have different x-over frequency points for each loudspeaker set.
For example..
  • Front L/R could be 80Hz
  • Center may be 100Hz
  • L/R Surrounds 150Hz

In the above example, the frequencies above (high pass fitered) would go to the respective loudspeaker and the frequencies below (low pass filtered) would be summed together (Front L/R + Center + Surround L/R) merged with the LFE track (.1) and sent to the Subwoofer. Also note that all of these tasks are done digitally within the audio DSP processor chip...

Just my $0.00... ;)
 
P

PENG

Audioholic Slumlord
I fully agree with you. It's a big part of why I ruled out Axiom's M22 and companion pieces when I was looking at speakers for my bedroom. Besides not wanting rear bass ports I did not want a system with a center and surrounds that would have to be crossed over at 100hz. Instead I'll be going with 5 identical speakers.
Crossover at 80 hz is not always a bad idea even if your surrounds competent down to 20 hz. Low frequencies produced by so many speakers in the same room can be problematic.
 

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