# AV Receiver: use as bi-Amp?



## charles_b (May 10, 2010)

Hi there!

I am wondering if it probably would pay off to use a 5.1 Receiver as an advanced machine for Bi-Amping.

My idea is to put the frequency deviding network (2-way-speaker-system) in front of the inputs of the 5.1-input.
Thus the low frequencies may got to speaker A (for instance) and the high frequencies may go to speaker B. 

The advantage would be to amplify the two parts of the spectrum separately. In addidion, the Recievers compensate for the distance of the A-pair and the B-Pair from the listener. Therefore some playing around with the time base (and shift) should be possible between lower and higher frequencies. 

Does anybody in here tried that before? How would one have to select the frequency dividing network? Do I need additional protection agaings "wrong" frequencies in the tweeter (not to kill it with low f)?
Any experience with the spatial variations one gets playing with the time-shift?


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## Dale Rasco (Apr 11, 2009)

I think I am confused. Are you asking what device to use to divide the frequencies of a single channel?


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## charles_b (May 10, 2010)

I would like to connect the 2 tweeters to the output of speaker-pair A, the woofers shoud connect to the outlets from B.

To make sure the tweeter gets only the high-f and the woofer the low-f my idea is to hook up a frequency dividing network (coils, capacitors and resitors) in FRONT of the inputs - with the effect that the amplifier for A would have to deal only with the higher frequencies.

The networks in the speaker itself are designed for 4 oder 8 Ω - which is not the input impedance of the Receiver. So part of my question is, yes, how would I have to set up the deviding network.

On the back of my Rec there ia a MULTI CH INPUT with six cinch-sockets: Left Front, Right Front, Left Souround, Right Sourround, Sub, Center.
I will not use the Sub and the Center but only the first 4 inputs. 
Left Front should get only the high f from the left channel, and so on.


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## Dale Rasco (Apr 11, 2009)

Ok, I think I know what you are saying, but the terminology you are using is throwing me a bit so let me try repeat it back to make sure I understand.



You want to split the frequencies so that the high range plays the higher frequencies and the mid plays the mid range frequencies. One of the problems with doing this is that your speakers are already designed to only produce a certain spectrum of frequencies. If you want to prevent the midrange speakers from producing the higher frequencies then you will need to incorporate some sort of manual crossover device. Additionally, trying to send multi-channel signal directly to the speaker without first running to a power amp will not work as there is no power going to the speakers.

Let me know if I missed something and I'll be happy to flesh it out a bit more.


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## charles_b (May 10, 2010)

I am sorry for mixing up the language. I made a drawing of my idea - hope it helps.


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## Dale Rasco (Apr 11, 2009)

Aha! Now I understand. Thanks for putting up the pic Charles, that helps. Two questions:


Does your receiver allow you to set the crossover?
Why exactly are you doing this?


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## charles_b (May 10, 2010)

Dale Rasco said:


> Aha! Now I understand. Thanks for putting up the pic Charles, that helps. Two questions:
> 
> 
> Does your receiver allow you to set the crossover?
> Why exactly are you doing this?


Hi Dale!
1. The Receiver has several Options for Input. One of them ist the Multi-stuff-field. The manual says that the Receiver will override any sound programms and so on if this input is chosen so the signals are more or less just amplified and forwarded to the speaker outputs. 

the crossover would have to be an extra box (maybe just a capacitor in series should do to cut out the low frequencies)


2. My idea was to build a quasi-active speaker system. If it works I could adjust the volume of low or high frequencies indepently. I could also play around with the time-shift option of the receiver, which allows to compensate for the different distances of the speakers with respect to the listener. (In fact, one has to enter the distance in meter or feet, but the effect is that the signals are delayed).

Of course, what it will sound like if only the highs ( or the lows) are delayed with respect to the other part of the spectrum - I have no idea how that will sound. On the other hand I have seen speaker systems where one could adjust the tweeter in the range of several centimeters back and forth with respect to the woofer. They claimed to be able to achieve a very good sound picture.


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## Kal Rubinson (Aug 3, 2006)

Your terminology is still wrong. The output amp terminals on a 5.1 receiver are FR/FL/C/SR/SL/Sub. The A and B terminals, if there are any, come off the *same *amps, so there is no biamping possible with them. Also, there are no settings for distance/level that differentiate between A and B outputs.

Also, if you use the multichannel input for your 4 channels as you have diagrammed, most receivers will bypass all level/distance processing.


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## charles_b (May 10, 2010)

Thanks for the hint. Of course you are right. A and B are parallel and get their signal from the front channels. So "front" and "rear" is correct.

I will check out what can be influenced when the Mutli-Ch-Input is used. If everything is fixed my idea may be not so goog then.

Let me post my results in a few days!


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## mozez (Aug 6, 2011)

Just curious, if I want to biamp, would it make a difference in home theater, will I need 7.1, any help, thanks. I wanna be able to give my fronts more power without getting separates but I wanna maintain the "surround sound" any help


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## Kal Rubinson (Aug 3, 2006)

mozez said:


> Just curious, if I want to biamp, would it make a difference in home theater, will I need 7.1, any help, thanks. I wanna be able to give my fronts more power without getting separates but I wanna maintain the "surround sound" any help


You would need a 7.1 AVR that permits biamping when in a 5.1 setup. It will make as much difference as in a stereo setup which, imho, is nil. Still, it is free and you can judge for yourself.


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## RTS100x5 (Sep 12, 2009)

To simplify the quest for bi-amp in a 5.1 system I am considering using these*** "active crossovers" which would, obviously require some additional amplifiers - but seems to me to be the lesser of 2 evils - that being inline crossovers (adding distortion and anomalies) VS active crossovers which introduce less distortions but significantly increase the cost of the system 

****http://www.newclassd.com/index.php?page=60

This company also makes some top end amplifiers / opamps / voltage regs and the like for the DIY's


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## Kal Rubinson (Aug 3, 2006)

RTS100x5 said:


> To simplify the quest for bi-amp in a 5.1 system I am considering using these*** "active crossovers" which would, obviously require some additional amplifiers - but seems to me to be the lesser of 2 evils - that being inline crossovers (adding distortion and anomalies) VS active crossovers which introduce less distortions but significantly increase the cost of the system
> 
> ****http://www.newclassd.com/index.php?page=60
> 
> This company also makes some top end amplifiers / opamps / voltage regs and the like for the DIY's


You should compare these with the established line from Marchand. I've used these with excellent results.
http://www.marchandelec.com/


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