[hdshark]

The new Panasonic SA-XR70 appears to support bi-amping (in addition to bi-wiring which is also supported by SA-XR50) according to the link to the User's Manual which was posted on another thread here.


I could not find any info in the user manual about whether the XR70 supports some kind of an active crossover function. If I understand it correctly, signals are kept in the digital domain until the final amp stages in this receiver, so implementing some kind of a digital filter to provide a programmable active crossover would be rather easy. They could even have templates for many of the popular speaker brands that support bi-amping.


Without a built-in active crossover, I don't see how the bi-amp option would be useful on this device.

 

[hdshark]

Isn't there anyone out here who is interested in using an XR70 in biamp mode?

 

[AkaStp]

Try this...

http://www.avsforum.com/avs-vb/showt...4&pagenumber=6


and this...

http://www.avsforum.com/avs-vb/showt...4&pagenumber=2


A search might turn up more.

 

[hdshark]

I have read through all the XR50 and XR70 threads on this forum as well as the XR50 and XR70 manuals. XR50 only supports biwire config, it does not support biamp mode. The XR70 supports biamping by internally wiring two of the surround sound amps to the B speaker outputs in this mode. However, I haven't been able to find any info about the details of the biamp function in the XR70 - specifically if any type of active crossover functionality is available.


The general question I have is, without an active crossover, what would be the benefit of biamping? If you have a passive crossover in the speaker, it may be useful in driving a lower impedance speaker (for example a 4-ohm speaker which is not officially supported according to the Panasonic datasheet).


If I understand correctly, the real useful case for biamping is when the passive crossover in the speakers are removed and the signals going to the woofers and tweeters are driven by separate amps. This is not likely to give good results unless an active crossover is used before the final 4 amplifier stages to low-pass filter the signals going to the woofers and high-pass filter the signals going to the tweeters.

 

[gpshumway]

The biggest benefit of biamping without an active crossover is doubling the available power. Of course you use up four amplifier channels on only two speakers.

 

[hdshark]

So with the proper speakers, the result of using the SA-XR70 would be the configuration shown below. I can see how this can increase the total power output as the woofers and tweeters will be driven by separate amps. I guess the assumption is that the high-pass and low-pass filters that are in the loop will help isolate the associated amplifiers mostly drive the high and/or low frequency range.

 

[SoftwireEngineer]

hdshark,

You have it right now.

An advantage in having the crossover in the amplifier is that you dont have to have one in the speaker. Just need the drivers.

If the amplifier is operating in digital domain, like these digital receivers, this should be easy to implement. I think this is what you want.

Since most speakers are sold with the crossover anyways, such a feature is not a requirement for the consumer market. Surely pros and serious diy audiophiles will like it.

Newform Research sells speakers without crossover or a way to go around the crossover and suggest using a Behringer digital crossover and using 4 of the 6-channel DVD input in the Panasonic.