Bi Amplification of speakers

GeorgeV

Standard Member
Anyone out there with experience on biamplification?
I would like to know if there are real or perceived differences b/w biamplification or not.
If you were to bi amplify a speaker with 4 binding posts would you need to delve inside the innards of the speaker to disengage the crossover? Or do you just connect to the four posts as you would when you bi wire? I understand you would have to use an external active cross over b/w the pre and the power amp.
Plesae let me have your comments and thoughts.
George.
 
B

bobbypunk

Guest
To Bi-amp you connect a suitable pair of amps whether suitable intergrated and additional power amp (pre out to main in), or pre amp and two power amps (pre out1 to amp1, pre out2 to amp2)(if only 1 pre out just split the signal).
They connect as standard but amp 1 connects to HF and amp 2 connects to LF, The bar that connects LF and HF must be removed (these are external).
That is it!
The difference in my experience is quite big not necescerily twice as good but always been better.

Memories flood back of the testing the differences, especially the Rotel Pre - 3 x Power Tri wired into Acoustic energy AE509s
Yes it definately makes a difference IMHO.
 

MarkE19

Moderator
Ditto the above :smashin:

Yes it is as easy as just removing the external link between the 2 binding posts and running 2 sets of speaker cable back to the amps. I would also say the improvement made the cost worthwhile.

Mark.
 

GeorgeV

Standard Member
Does this not still leave the passive crossover inside the speaker still actice and causing interference with the signal?http://sound.westhost.com/bi-amp.htm The article here I found and is quite detailed but perhaps too technical for my understanding. It would seem that you have to disconnect the internal crossover and use an active external crossover too. Thoughts on that? If that were the case, how do you disconnect the internal crossovers? In this case B&W CDM 9NT's.
Could an X 30(paradigm do this)?
George.
 

Nic Rhodes

Distinguished Member
Biamping uses the speakers internal 'passive' crossover, it sounds better because of reduced IM distortion (like a bigger amp).

Removing the internal crossovers and replacing with active ones is not biamping but active. It is potentially the best way to do things.

Biamping is 'in the middle and easily done'
 

Nic Rhodes

Distinguished Member
A bi wired speaker separates out bass and treble crossovers (in the speakers) and you run two speaker cables from a common amp. Many including me think it is rubbish if your cross over is well designed.

The crossover in the speaker uses big capacitiors, resistors and inductors to filter the various frequencies being sent to woofers, mid and tweeter etc and level balance the speaker levels.

A bi amped speaker uses the same crossovers as above but has two amps driving the speakers bass and treble units separately. This means there is less InterModulation distortion (IM). The bass signals use up most of the amps 'headroom' for want of better term quicker than the treble signals. This means that the treble signals which ride along with the bass signals also get distorted normally (see biwiring and ordinary wiring speakers) even though they are not clipping themselves, it is just the action of the bass signals 'effecting' the treble signals. Biamping greatly reduces this IM and ‘ball park’ is much like significantly increasing you amp power if you had a single bigger amp. There is a 4 dB advantage here.

The crossovers for the above both work at power levels (power rating of speakers), say 10 to 400w. They do however produce significant distortion which at non bass frequencies is all too audible.

Active speakers remove this 'power' crossover. This greatly reduces Total Harmonic Distortion (THD) which the above crossover produces. (x% down to 0.001% THD) A new crossover circuit does the same job to filter the various frequencies being sent to woofers, mid and tweeter etc and level balance the speaker levels. BUT this time, rather than at ‘power level’, it does it at line levels (those tiny power signals being sent down the RCA connectors we all love). Then separate amp power the separate drive units AFTER the crossover rather than before in the bi amping. The crossover is BEFORE the amp now rather than after it.

Bi amping reduces IM

Active speakers reduces THD and IM

Bi wiring is tosh

Active speakers are the BEST I know, I would dearly love some new ones but money and young family…….I have been using active speakers with my PC for 15 years now  They have been turned off twice for two moves

Bluesky, Mackie, Genelec produce some stunning speakers for pro (but brilliant for AV / HIFI as well). ATC, NAIM, LINN and other have always advocated this approach but it can get silly money as my local Linn dealer scared me with on Monday. But active is the best technical solution I know, BUT they also sound the best.

Bluesky and many others however make speakers with amps in the £275 to £375 per active speaker, this is generally two channels of amps and speaker. Their performance is awesome but to get the most out you need a sub but most AV enthusiasts have this already but don’t realize what they can do. This is the best way forward IMHO and reduces many amplifier boxes as well. Important to many.

Full range signals need significantly more power than we normally use for AV and Hi Fi currently. Most of our full range amps are grossly under powered for full range signals. Cost thing purely. To solve this either use a 450w amp and bigger or hive off the amp grabbing signals elsewhere (bass). An active bass unit (subwoofer) which most of use already in AV accomplishes this and leave the rest free to use the best options. However we still insist in shooting ourselves in the foot in Hi fi and AV by setting our speakers to full range and not using an active sub where ever we can. It is daft and makes no sense other than people don’t know what they are doing.

Amps need to do two things:

1. They need to be of the quality we want (distortion and all that)
2. They need to be able to drive the speaker we have, to the level we want in the room we have.

THESE THINGS ARE SEPARATE

Most people cock up either 1 and / or 2. It costs them money. Fortunately like wires, subs and many other issues it is not difficult to do correctly.
 

GeorgeV

Standard Member
Thanks.
I need some clarity on the crossovers inside the speakers.
My intention(pls.inform me if I am making sense or not), Run my normal sub out from the processor(A1SR), to myactivesubs(two servo 15's). Then the L & R pre outs to an X 30(active crossover), from which I will output the sub outs into the power amps and then to the low frequencies of the speakers, and from the 120Hz high pass(allows frequencies above this) to the high frequencies of the speakers. This way I split the signals before getting to the power amps(2x proceed amp 2,s) and then to the speakers(connections b/w the binding posts removed).
Do I still have to go into the speaker and separate the crossover internally? or just by removing the connection have I done that?
By using exactly the same amps, have I taken care of issues aroung "gain".
Thanks.
 

GeorgeV

Standard Member
Sorry, missed out sth else.
If I were to replace my existing fronts(B&W CDM 9NT's) with the 1NT's and set them to small thus routing the lows to the subs, would I be better off?
 

Nic Rhodes

Distinguished Member
I do something 'similar' but you will have to go into the speaker to remove the crosover. Do remember that cross overs do may things, not just splitting the freq spectrum. Things like equilization (drive units have different sensitivity), phase correction, notch filyer etc etc.What you are suggesting is not trivial to do 'properly'.
 

GeorgeV

Standard Member
Probably not something a newbie/untechnical person should attempt on my own. Though that would be the real way to bi amp properly.
If one did not do that but simply connected to the binding posts from the split signal(coming from the active Xover) would that give some sonic benefit, or would th passive xover still in the speaker still"interfere"?
Sryy for what may seem basic questions to some, but I guess thats what a forum is for.
 

Nic Rhodes

Distinguished Member
You would be going through two crossover (well actually two analogue and one digital) which is not good. Wost of both worlds. What your best compromise is bi amp or use bigger amps
 

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