RXV2700 Auto Setup

[jeremy4130]

Another question i have is when i ran the auto setup it assigned my fronts as small and my center and surrounds as large. I ve ran it several time and sometimes it will assign the center as small too. I have B&W CM series fronts, center and surrounds. The front are full range, so i dont understand why it thinks they are small. the center and surrounds are just tweets and mids, so i dont understand why it thinks these are large. Its also assigning a crossover frequency at 160hz (i think), this is also confusing to me. Im pretty new to this stuff, only been in it for about 3 years. I know the auto set up isnt the be all end all of how the system should be set up. Im just curious why it would think these things.

 

[Pyrrho]

It is very common for the automatic setup to mistakenly call a "small" speaker a "large" one, but not so common for it to make the opposite mistake. My guess off the top of my head is that there may be a dip in the frequency response, possibly due to room placement, at just under 160 Hz for your main speakers.

What I recommend, after you make sure you have everything where you want it, is to "correct" the errors in the manual setup after having run the automatic setup (making sure the microphone is positioned in accordance with the manual's instructions). When I do the auto setup with mine, it "decides" that all my speakers are large, sets the crossover at 40 Hz, and sends the bass to both the front and the subwoofer. I change this to have every speaker set to small, move the crossover up to 60 Hz (and am thinking about setting it at 80 Hz), and send the bass only to the subwoofer. It does, however, seem to get the delay (distance) right and the level seems good, so I am glad to have the automatic setup.

Just to be clear, you have the CM7, CM1, and CM Centre, right? Oddly, according to B&W's web site, the front CM7 speakers have the -3dB point at a higher frequency for the bass than the smaller CM1! In your case, I would set the crossover at 80 Hz, and make sure that all the speakers are set to small. If B&W's web site is right, there is something odd that they are doing with those front speakers.

And one more thing: A speaker whose -3 dB point is at 62 Hz is not what should be called "full range", so your front speakers are properly "small" in the receiver settings. It is not a question of how big the speakers are physically, it is a question of how low they go before the sound starts to trail off that determines whether a speaker is "large" or "small" in the settings.

 

[jeremy4130]

actually its an older CM series. The CM4 the CMC and the CM2's. As long as the system sounds good, i dont care how I have to set the speakers. I had assumed (i guess incorrectly) that because the fronts had a tweeter, a midbass, and a woofer, it was a full range. The cross over was confusing to me, setting it at 80hz sounds reasonable.
thanks for your input.

 

[Pyrrho]

In that case, I would set it at 80 Hz for the sake of the center and rear speakers. If all of your speakers were like your front ones (judging from the specifications at B&W's web site), you could set it at 60 Hz, but since they are not, you should select 80 Hz (or above).

Still, from what your receiver is doing, it seems there must be some sort of dip in the frequency response of your front main speakers somewhere just below 160 Hz, if that is the setting your receiver selected for them. You might want to consider moving them slightly and rerunning the automatic setup, but that may not be practical depending upon what kinds of arrangements are possible in your room.

Basically, the function of the crossover settings is to limit the frequencies that are sent to the "main" speakers (i.e., all non-subwoofer speakers) because they cannot handle all frequencies, and send the frequencies that are too low for them to the subwoofer. (It is much cheaper to do things this way, instead of having 5 truly full range speakers to deal with it all.) So, you want your crossover set at a frequency that is higher than the lowest frequency that your main speakers can handle well. Since your rear and center speakers are at -3 dB at 65 Hz, you need to set the crossover above that to get all the sound and limit distortion caused by asking speakers to reproduce frequencies that they are not capable of adequately doing. This also takes some stress off of the power amplifiers in the receiver, as this means that the amplifiers will not be trying to put out power in those lower frequencies; it will leave those frequencies for the subwoofer to deal with.

What I forgot to mention in my previous response is that the reason why your receiver may confuse a small speaker for a large one is that it does not check frequencies below a certain point (I cannot remember off the top of my head what the frequency is, so I will not say a particular number presently), so if the speaker can do that frequency, it is "thought" by the receiver to be full range. That is what is happening with my speakers, which are rated to have a -3 dB point at 50 Hz, and are capable of some output below that.

If you wish, you can also tell your receiver to not bother with the automatic crossover setting in its automatic mode. Take a look at the manual to see how that is done with the RX-V2700, if you don't want it to reset the crossover frequencies every time you run the automatic setup.

 

[jeremy4130]

i am home now, and i will set it up the way you suggested and see how it goes.