Bi-amped dual mono or Bridged dual mono setups

[Zappa]

Hi all

I am new to the mystical art of Bi-Wiring, Bi-Amping, Mono Blocs and all the other terms which I do not completely understand.

I have watched and read countless posts/YouTube Videos on the subject, but I still don't get it, hence the post, so apologies if this has been asked before.

My current system is all Cambridge Audio.

2 x Azur 851W Amplifiers (1 x 851W not currently setup)
(Power output – stereo/mono
200W per channel into 8 Ohms 350W per channel into 4 Ohms

Power output – bridged mono
500W 8 Ohms 800W 4 Ohms)

1 x 851N Network streamer and DAC (I have this set as a digital pre-amp)
1 x 851C CD Player & DAC

In an ideal world I would also have the 851E (Pre-Amplifier) but I cannot find one

Speakers are Mission Floor standing 782SE's

Closure Type – 3-way reflex loaded
Frequency Response +-3dB 48Hz to 20Hz
Cross over Frequency 195Hz & 2.5Hz
Impedance 8 Ohms
Recommended Amplifier 5-200—W/Ch

Speaker cables are Van Damme with banana connectors of which I have 4 pairs

I am interested in the dark art of Bi-amping and based on what equipment I have, would like to know which is the preferred method.

Cambridge Audio tell me I can configure the 851W's in either Bi-amped dual mono or Bridged dual mono setup which I am assuming is.

Vertical bi-amping = One stereo amp per side. One channel for high frequencies and one for low or Horizontal bi-amping = One amp for low frequencies. One channel for left one channel for right. One amp for high frequencies etc:

Room Size is 8m x 5m

Any suggestions on which option or any other scenarios would be the best setup appreciated

Thanks

 

[Sergeauckland]

I'm not surprised you don't get it, as there's nothing to get!
Passive bi-amping, i.e. where you retain the passive crossovers in the loudspeakers is completely pointless, and is only a ruse to sell more power amps and cables.

It CANNOT do anything, as each power amp is still seeing the same voltage and as long as the power amp can support the load, then splitting LF and HF does nothing.

For why, look up The Superposition Principle. Briefly, this states that in a linear system (and modern power amps are very linear), current drawn at one frequency have no effect on currents drawn at other frequencies.

If you're bi-amping with active crossovers, i.e. removing the passive crossover in the loudspeakers and putting an electronic crossover before the power amps, then there are real benefits in terms of maximum loudness, reduction in intermodulation distortion (although this is small) reduction in harmonic distortion, improvements in smoothness of frequency response and off-axis behaviour because of steeper crossover slopes.

Passive bi-amping has been on the biggest cons in HiFi, and deserves to be roundly condemned.

S.

 

[Zappa]

Thanks for your comments and I know which side of the fence you stand.

However like with any good debates, there are plenty of others stood the other side who say otherwise, you only have to search on YouTube and you will find both sides of the story and most are not amplifier manufacturers.

My situation is different however, as I already have the hardware, having had it left to me from a late Uncle, I would rather he still had it, but we are where we are, so selling the equipment is not an option.

Therefore, given the current hardware I have, what would be the best way to connect to give the optimum performance, for a newbie there is a plethora of conflicting information out there, hence my original question.

I am not interested in volume, its loud enough already and from what I have read the increase in decibels is minimal, I am more concerned on the quality and richness of the sound.

I can understand the debate that the difference in a bi-amp setup is minimal and therefore not worth the expense of going out and buying an identical stereo amp, I am not in that scenario.

Regards

Z

 

[Sergeauckland]

Regardless of the debate, (I only debate technical matters, not of anecdote and opinion) as you won't be making any changes to the loudspeakers, however you passively biamp, vertical or horizontal, the result will be the same, you choose, whichever makes the cabling easier.

There may be some small (inaudible) benefit to keeping one power amp for left and the other for right as then crosstalk is minimised and one can site each power amp next to the loudspeaker it's feeding, and have very short loudspeaker cables.

S

 

[Zappa]

Thanks for the advice, appreciated.

Regards

Z

 

[Zappa]

For anyone interested I now have had the chance to test the different combinations of my 2 851W's in a Bi-Amp Mono setup.

There is definitely an audible difference when in Bi-Amp mode, ie. one amp looks after the left speaker, the other the right.

I tested with one amp in normal mode (Stereo), same song same volume 63% and in single stereo mode decibel meter read a maximum 79.6 playing Chris Rea Road to Hell for reference (other songs tested as well)

Then tested same volume & song but in Bi-amp mode (two amps connected) and decibel meter read maximum 85.2

Meter was read same distance away each time, only difference was whether I was in Single Stereo mode or twin amp mono mode.

The sound is also much fuller in Bi-amp mode, so for me I'll be keeping my amps in Bi-amp mode

Z

 

[Sergeauckland]

Fascinating.

I'd like to know more about the settings. Are you sure the amps weren't in mono (i.e. bridged) mode?
It's suspicious that you report something very close to 6dB increase in output when there's no reason for it whatsoever. I would expect no increase in output, as each amplifier is still seeing exactly the same input voltage whether being used in stereo or bi-amped.

S.

 

[yespsb]

Interesting post and replies, I hope others will chip in as its a subject I am interested in but have no experience of

 

[KC²]

Hi Zappa,
After reading about your experience with CA851w I decided to test my own and wired it as mono/bridge to one of my b&w 603. I have to say wow, they literally came to life. The difference is staggering, on the same volume sound open up and I can feel/hear a lot more of bottom end. On Christmas I was considering adding subwoofer to my setup to get that extra zing and thank god my wife stop me . I think buying another 851w will do me more good then a sub. Thanks m8.

 

[Arkless Electronics]

In fact passive bi amping can make an improvement but don't expect any vast difference. Horizontal bi amping will often (but not always. See below and suck it and see as they say!) be best as then the amp handling the top end is not seeing any real load at bass frequencies where the greatest power demands are and hence the top end is coming from its own amp which is "just idling" and not under any stress. The amp driving the woofers would have to drive a pair of woofers anyway if you were not bi amping so no great loss there (but see below). Another advantage to bi amping is that if "giving it some welly" (that's a technical term) to the extent that the bass amps run out of power and clip then the tweeters don't see the clipping as they are powered from another amp/channel which is just loping along and should therefore not be damaged.

OTOH an advantage to vertical bi amping is that each amplifier is near as damn it then using the entire PSU just to power one bass driver via one amp channel (on typical programme material the woofer will be taking >80% of the power and the tweeter a fairly negligible amount).