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JohnJohn

To Bi-amp or not to Bi-amp

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that is the question. I always have Bi-amped my Pioneer receiver to big old Klipsch speakers, whether it makes any audible improvements I'm not sure? But now I'm hooking up this https://www.intl.onkyo.com/downloads/product_info/pdf/tx-8390_euex_leaflet.pdf to these https://www.klipsch.com.au/products/rp-6000f-floorstanding-speaker - a 200w/ch classAB amp [I think] to 125w rated small floor standers. Perhaps bi-amping is unnecessary as the amp is rated well above the speakers??? Thanks in advance for your comments.

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Just looking at your amp, it’s a two-channel amp. So I think if you are connecting both pairs of terminals up to your speakers you’ll be bi-wiring rather than bi-amping. So you won’t actually be getting any more power. 
 

lots and lots of discussion to be had about whether that makes any difference.  Maybe give it a go and see for yourself. 

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1 hour ago, JohnJohn said:

that is the question. I always have Bi-amped my Pioneer receiver to big old Klipsch speakers, whether it makes any audible improvements I'm not sure? But now I'm hooking up this https://www.intl.onkyo.com/downloads/product_info/pdf/tx-8390_euex_leaflet.pdf to these https://www.klipsch.com.au/products/rp-6000f-floorstanding-speaker - a 200w/ch classAB amp [I think] to 125w rated small floor standers. Perhaps bi-amping is unnecessary as the amp is rated well above the speakers??? Thanks in advance for your comments.

 

Perhaps you need to get onto Rod Elliott's most informative web-site and read up about "bi-amping"?  :)

 

Are you aware there is "active bi-amping" ... and "passive bi-amping"?

 

Active bi-amping is where you remove (or bypass) the spkr's internal passive XO and use 2 channels of a receiver (or a stereo amp) to drive the woofers and another 2 channels (or a stereo amp) to drive the tweeters.  To make this work, you also need an active XO which provides the LP and HP filters that the internal passive XO used to provide.

 

Passive bi-amping is where you simply remove the metal connectors between the woofer binding posts and the tweeter binding posts - so you continue to use the internal passive XO but you drive the speakers with 4 amplifier channels, instead of 2.

 

It's generally agreed that passive bi-amping is a doubtful proposition ... in terms of sonic benefit.

 

Andy

 

 

 

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I don't see any point of bi-amping in your case. 

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1 hour ago, sir sanders zingmore said:

Just looking at your amp, it’s a two-channel amp. So I think if you are connecting both pairs of terminals up to your speakers you’ll be bi-wiring rather than bi-amping. So you won’t actually be getting any more power. 
 

lots and lots of discussion to be had about whether that makes any difference.  Maybe give it a go and see for yourself. 

ah yes, you are correct - it supports bi-wiring, not bi-amping - stupid of me....

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Bi-amping - it depends.

If the system does not have enough detail there will be no audible difference in bi-amping. However if the system can retrieve a lot of detail the difference is audible. IME ( 35 years as a technician early years with Marantz) bi-wiring make Zero difference.

 

My system is bi-amped I use Rod Elliot's active XO between the preamp and power amps. The system is detailed enough that it is audible. Measurements via REW THD was lower at 1kHz.

 

The biggest advantages are, amp connected directly to the drivers so any damping is not via passive components, and reduced IMD in some cases.

 

 

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10 minutes ago, Warren Jones said:

Bi-amping - it depends.

If the system does not have enough detail there will be no audible difference in bi-amping. However if the system can retrieve a lot of detail the difference is audible. IME ( 35 years as a technician early years with Marantz) bi-wiring make Zero difference.

 

My system is bi-amped I use Rod Elliot's active XO between the preamp and power amps. The system is detailed enough that it is audible. Measurements via REW THD was lower at 1kHz.

 

The biggest advantages are, amp connected directly to the drivers so any damping is not via passive components, and reduced IMD in some cases.

 

 

thanks so much!

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49 minutes ago, Warren Jones said:

Bi-amping - it depends.

If the system does not have enough detail there will be no audible difference in bi-amping. However if the system can retrieve a lot of detail the difference is audible. IME ( 35 years as a technician early years with Marantz) bi-wiring make Zero difference.

 

My system is bi-amped I use Rod Elliot's active XO between the preamp and power amps. The system is detailed enough that it is audible. Measurements via REW THD was lower at 1kHz.

 

The biggest advantages are, amp connected directly to the drivers so any damping is not via passive components, and reduced IMD in some cases.

 

 

 Bi-amping using an active crossover (as you do) makes a substantial difference. 
With a passive crossover this is not so clear - or at least has been the subject of much heated debate on hifi forums for years

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On 25/12/2019 at 4:40 PM, sir sanders zingmore said:

 Bi-amping using an active crossover (as you do) makes a substantial difference. 
With a passive crossover this is not so clear - or at least has been the subject of much heated debate on hifi forums for years

 

On 25/12/2019 at 3:47 PM, Warren Jones said:

Bi-amping - it depends.

If the system does not have enough detail there will be no audible difference in bi-amping. However if the system can retrieve a lot of detail the difference is audible. IME ( 35 years as a technician early years with Marantz) bi-wiring make Zero difference.

 

My system is bi-amped I use Rod Elliot's active XO between the preamp and power amps. The system is detailed enough that it is audible. Measurements via REW THD was lower at 1kHz.

 

The biggest advantages are, amp connected directly to the drivers so any damping is not via passive components, and reduced IMD in some cases.

 

 

There is an innate advantage regardless (to genuine bi-amping) regardless of everything else... power increase. 

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1 hour ago, furtherpale said:

 

There is an innate advantage regardless (to genuine bi-amping) regardless of everything else... power increase. 

Sorry, it's not 100% clear to me what you are saying.

If you are saying that bi-amping with an active (but not a passive) crossover delivers a power increase, then I agree.

If you are saying that bi-amping with either active or passive crossover delivers a power increase, then I disagree.

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8 hours ago, sir sanders zingmore said:

Sorry, it's not 100% clear to me what you are saying.

If you are saying that bi-amping with an active (but not a passive) crossover delivers a power increase, then I agree.

If you are saying that bi-amping with either active or passive crossover delivers a power increase, then I disagree.

If you leave the bus pins in on a speaker, and run a 100 watt mono block into the speaker, you’re feeding it 100 watts.

 

If you take the bus pins out and run 2 x 100 watt mono blocks, you’re feeding it 200 watts.

Edited by furtherpale

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17 minutes ago, furtherpale said:

If you leave the bus pins in on a speaker, and run a 100 watt mono block into the speaker, you’re feeding it 100 watts.

 

If you take the bus pins out and run 2 x 100 watt mono blocks, you’re feeding it 200 watts.

 

But your 2x 100w monoblocs still clip at 100w.  Rod Elliott explains it all.  :)

 

Andy

 

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22 minutes ago, andyr said:

 

But your 2x 100w monoblocs still clip at 100w.  Rod Elliott explains it all.  :)

 

Andy

 

Do you have a link? (Sorry - don’t know where to start searching that one).

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1 hour ago, andyr said:

 

But your 2x 100w monoblocs still clip at 100w.  Rod Elliott explains it all.  :)

 

Andy

 

This is correct - and to add the bass/woofers will use most of the power. To clip 100w power amps either you have no hearing or the speakers are very inefficient.

 

I am not a fan of using power figures anyway as it's meaningless by its self.  To give an example my speakers are 96db/w at 1m so they do not need any more than 5watts to shake the house. My amplifiers are 25w/ch at 1V input but my preamp is passive so input is less than 500mv so the amps will not make 25w and they CANNOT clip.

 

start here

https://sound-au.com/bi-amp.htm

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My understanding is ...

 

In a non-active bi-amp system ....

 

  • The speakers still have a passive XO albeit split by the removal of the "bridge/bar/jumper" thing.
  • Assume XO at about 300Hz ie. 50% power for each half. [Bass and mid-range+treble power are normally split 50/50 at about 300Hz, not that that matters.]
  • Both 100w amps are still each powering the full frequency range.
  • This full range is being sent to the "woofer" part of the passive XO by one amp.
  • This XO then throws away the other part of the freq range, (the mid and high freq bit).  So half of that amp's power is discarded (as heat? or to earth? in the XO).
  • The same for the XO that the "mid+treble" amp is powering; it is throwing away the bass portion.

 

So even though 2 amps, only half the power of each is being used.

2 x 1/2 = 1 or

1/2 + 1/2 = 1 or

0.7 + 0.3 = 1 or whatever depending on the XO frequency

 

The situation is different when the XO-ing is done before the power amps ie, active bi-amping.

 

Active bi-amping is the much preferred method if the speakers allow it or if one is prepared to disconnect/modify the passive XO.  Passive bi-amping and bi-wiring are considered ineffective by many including Elliott.

Edited by aechmea
easier to read

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1 minute ago, Warren Jones said:

This is correct - and to add the bass/woofers will use most of the power. To clip 100w power amps either you have no hearing or the speakers are very inefficient.

 

I am not a fan of using power figures anyway as it's meaningless by its self.  To give an example my speakers are 96db/w at 1m so they do not need any more than 5watts to shake the house. My amplifiers are 25w/ch at 1V input but my preamp is passive so input is less than 500mv so the amps will not make 25w and they CANNOT clip.

 

 

WJ, you would seem not to agree with the commonly-held 'rule' that you need to provide 10x 'normal' power usage, to be able to deliver transients cleanly?  In your case, if you're "shaking the house" at 5w ... that would be 50w.  :)

 

And as regards clipping:

  1. I distinctly remember visiting an SNAer's house about 10 years ago, who had a device (a 'response-shaper' - there's a better name for them ... which I forget!  :( ) which had vertical rows of LEDs for the different frequency bands.  The more LEDs that lit up ... the nearer you were to max power delivery.  With the music he was playing, the tweeter LEDs were consistently more lit up than the bass LEDs!
  2. I am about to start building some new amps for my mids & ribbons, in my 3-way active system (so 4 channels of amplification in all).  These amps are designed with a 'clip LED' - which comes on when the output voltage gets to the DC rail voltage.  I will be most interested to see how often these clip LEDs come on, on the ribbon amps.

 

Andy

 

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It depends on the signal you're amplifying as to whether actively crossed over speakers are getting more power...

 

If you are feeding a 20Hz signal and amplifying that maximally out of a single 100W amplifier you get 20dB of amplification out of it

If you are feeding a 20kHz signal and amplifying that maximally out of a single 100W amplifier you get 20dB of amplification out of it

If you are feeding a combined 20Hz + 20kHz signal and amplifying that maximally out of a single 100W amplifier you get 20dB of amplification out of it - ie you cannot get 20dB of bass and 20dB of treble out of it.

If you are feeding a 20Hz signal and amplifying that maximally out of two biamped 100W amplifiers you still only get 20dB of amplification out of it

If you are feeding a 20kHz signal and amplifying that maximally out of two biamped  100W amplifiers you still only get 20dB of amplification out of it

However

If you are feeding a combined 20Hz + 20kHz signal and amplifying that maximally out of two biamped 100W amplifiers you get 23dB of amplification out of it - ie it acts like having a single 200W amplifier.

 

But, most music content is exponentially less dense in energy as the frequency rises, so you will virtually never get as much energy at 20kHz as you get at 20Hz, so for the vast majority of the time, a single 100W amplifier is equally loud as 2x100W biamped amplifiers.

 

EDIT: Passive still needs to amplify everything regardless and doesn't benefit from this. I made a typo in the original post.

Edited by Ittaku

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21 hours ago, andyr said:

 

WJ, you would seem not to agree with the commonly-held 'rule' that you need to provide 10x 'normal' power usage, to be able to deliver transients cleanly?  In your case, if you're "shaking the house" at 5w ... that would be 50w.  :)

 

Andy

 

I know my views are somewhat at odds to what is bandied about in the forums, but I have been a tech for 40years starting my life at Marantz and ending in a Military Cal Lab. I have repaired and performance tested a lot of different equipment so my views are based on my experience.

 

I have measured the peak voltage at the speakers with music using a peak hold on my Fluke to ensure the amps never clipped. At slightly higher than normal listening level, peak voltage on the speakers never went above 6vRMS well below the +-28v rails

 

Transient response is directly related to voltage. As long as the transient does not exceed the amps voltage rails your good. If it does then the rails will collapse because the power supply cannot supply the current to drive the speaker at that voltage level. Yes I know IV is power but 50W can be be 50amps 1V or 2amps 25V both = 50Watts, so I would rather know what the voltage rails are more than what power the amp can supply.

Edited by Warren Jones

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Bi wiring seems like a waste of speaker cable.. I still do it for my second setup. Mainly because its longer run cables so my theory was it may lose less power by bi wiring

 

I would like to try active bi amping. What I have done in the past is had two power amps which were identical and I had identical equalisers running from my pre outs through the equalisers and then into the power amps, one for lows and one for mid highs, that was some fun playing around with.. 

Far too much power for my needs considering the power amps were 350watt into 8ohm each. Now I use one for my main speakers, they have a relay output for another amp so I use that to the second one which powers my outdoor speakers. 

 

If you have good speakers with good crossovers.. I wouldn't worry about bi amping. 

The way I did mention works beautifully though, you get a real idea of how speaker separation works

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