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Bi-amping With Active Crossover & Eq


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Eyup,

although I've been a mobile dj for about a million years, I've never tried bi-amping before & I could do with some advise. I've recently acquired some more gear and so here is what I've got to play with:

Gemini GX 400 speakers, D-Class CD15N Bins

3 amps: Kam KXR1500, Kam KXR1000,Synq Dig3K6

Kam KX050 Crossover, Kam KEQ152 Graphic and a BehringerVMX100 mixer (which also has an adjustable mono output for subs)

Any advice on matching amps & speakers and also wiring it all up would be gratefully received. Thanks (in advance) Deano

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Hi mate!

 

simple!

 

Do something along the lines of this:

 

Out of your mixer (Stereo Main)

 

Into you Eq then Out of your Eq

 

Into the Active Crossover

 

Then! Use the KXR1000 to power the tops and the KXR1500 to power the subs. Set the crossover freqency to anything between 90 - 120. Anything above 125HZ is NOT technically bass frequencies so keep it within these limits. I would suggest 100Hz as a starting figure. DO NOT use the crossovers inside the subs and link to the tops as these sub corssovers are pants! Trust me unless you spend mega bucks they are naff! You will get alot of leakage through them. Remember to always keep your amp gains at 100% and just level the bass and tops from the active crossover otherwise you get a form of harmonic distortion when turning the amp gains down.

 

This system should get you rocking and with an active crossover make the whole system about 10 times more efficient. And efficiency = loudness!

 

Have fun.

 

Billy :pizza:

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otherwise you get a form of harmonic distortion when turning the amp gains down.

 

Care to expand on this one then? I'm intrigued to know where this may have come from and what foundation it has in reality.

 

Could you be referring to the fact people tend to drive the mixer harder with amp gains down thereby causing the mixer to distort? If so, I wouldn't really consider that a function of having the amp gains down...

Edited by norty303

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Care to expand on this one then? I'm intrigued to know where this may have come from and what foundation it has in reality.

 

Could you be referring to the fact people tend to drive the mixer harder with amp gains down thereby causing the mixer to distort? If so, I wouldn't really consider that a function of having the amp gains down...

 

Hi norty303

 

Yeah brief explanation you hit on 1 of them already, but with most common amps like the kxr range although good budget amps the detented gain pots are quite cheap and on some amps have found that if the gain pot is turned to lets say 75% or 3 O'clock a third harmonic distortion can be heard on vocals. This has been proven myself on Berhinger and my KAM hire stock and other budget amps. It's something to do with the setup of the actual gain pot which is beyond my comprehension, however I have witnessed this on test. You don't even need a scope to see the audio signwave change it can be heard by anybody who can tell whn harmony is being used (which I would assume is most people). Was told by my partner who's an pa sound audio nerd for a living that this is a common feature on most budget or lower range amps. And yes the other one you got. Some people out there think cutting the amp gain you cannot get 100% power from the amp. As you know this isn't soo.

 

However for the budget end the KXR 600, 1000, 1500 and 2000 are cracking reliable pieces that do what they were designed to do.

 

I forgot to say. It's not a total loss at 75% it won't be noticed I should think when playing normal music. However it can clearly be heard if you are listening to a simple vocal or single note at reasonable listening levels. However for me just knowing it would do that is enough for me to leave the amp gains alone at 100% open despite it only being overly noticed on single notes.

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I hope you'll forgive my scepticism about that, particularly the specifics of the 3rd order harmonics.

 

Also, can you define 'leakage' in relation to passive filters? In my experience, they are what they are, with a slope as defined by the components. More expensive components will usually only make them more reliable and able to take more power, not change the characteristics of the crossover point/slope.

DIY plans and pro audio related technical discussions

www.speakerplans.com/forum

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Before being too derogatory about passive crossovers inside speaker cabs, many electronic crossovers, particularly the digital ones, have modelling software that simply reproduces the response curve of a passive one; because many people believe an analogue or passive crossover gives a more rounded, musical response; for example Butterworth, Bessel, Linkwitz-Riley (L-R) etc. An electronic crossover just gives you a large element of adjustment and many other features such as limiters, gain adjustments and EQ.

 

A poorly set-up electronic crossover will sound 10 times worse than a basic passive crossover that has, after all, been computer-designed with the drivers and cabinets of the speaker setup already put into the equation; especially if it's a so-called '4-box' set from the same manufacturer.

 

I really think this talk about amp gains set to less than 75% will introduce 3rd harmonic distortion is just so much nonsense.

 

 

Edited by superstardeejay

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Before being too derogatory about passive crossovers inside speaker cabs, many electronic crossovers, particularly the digital ones, have modelling software that simply reproduces the response curve of a passive one; because many people believe an analogue or passive crossover gives a more rounded, musical response; for example Butterworth, Bessel, Linkwitz-Riley (L-R) etc. An electronic crossover just gives you a large element of adjustment and many other features such as limiters, gain adjustments and EQ.

 

A poorly set-up electronic crossover will sound 10 times worse than a basic passive crossover that has, after all, been computer-designed with the drivers and cabinets of the speaker setup already put into the equation; especially if it's a so-called '4-box' set from the same manufacturer.

 

I really think this talk about amp gains set to less than 75% will introduce 3rd harmonic distortion is just so much nonsense.

 

Oh really?! :drama: :ads:

 

Ha! :wacko:

 

No nonsense at all proof is in the pudding all I say is try it with a budget amp you'll be suprised at the degrdation on some! Same for passive hi pass filters on subs for "leakage". Not got time for people who believe in using the subs crossover it's in-efficient - FACT! However. Simply cannot be bothered for "busybodies" trying to re-evaluate what I have given in advise to the original poster. Take it or leave it couldn't care less.

 

As for the original post hope you enjoy your new kit mate! :dukesy:

 

E'nuff said! :msn-wink:

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im curious as to how you suggest NOT using the crossovers in the subs, im not talking about the mid/high output here, im talking about the input on the bass cabs. The crossover included with the Class D's will have been selected for its suitability for that speaker and therefore should be the one thats used, unless you are suggesting that the OP bypasses the crossover internally. By using a Crossover before the bass amp, you are, in effect using 2 crossovers at the same time for the same thing

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  • 2 weeks later...
Oh really?!

 

Ha!

 

No nonsense at all proof is in the pudding all I say is try it with a budget amp you'll be suprised at the degrdation on some! Same for passive hi pass filters on subs for "leakage". Not got time for people who believe in using the subs crossover it's in-efficient - FACT! However. Simply cannot be bothered for "busybodies" trying to re-evaluate what I have given in advise to the original poster. Take it or leave it couldn't care less.

 

The problem I have with this is that I have yet to hear anything remotely similar from anyone, anywhere, despite having the collective knowledge of many decades and emminent speaker and amplifier designers knowledge and experience to hand.

 

What is a more common occurrence is for people to come to DJ forums and claim 'superior ears' with wild claims that they refuse to substantiate when called on it.

 

Noisy pots or crackly pots, particularly as they age - yes. 3rd order harmonics - not yet I'm afraid.

 

 

yes, passive crossovers do soak some power (re: inefficient statement) and I'm the first to advocate going fully active for improved sound quality and level, but 'leakage'? 12db/oct is 12db/oct however you read it, unless its designed as a lower or higher order, or the company mis-represent it (I know, we'll tell everyone its 12db/oct but really we'll put in those 18db/oct ones)

 

unless you are suggesting that the OP bypasses the crossover internally

 

Just for completeness in the thread, yes, if the cabs give you no external way to bypass the passive x-over then you should rewire direct to the driver if you are going to use an active crossover, or you'll start to suffer all sorts of phase anomaolies from the combination of shift providing by competing orders and frequencies

Edited by norty303

DIY plans and pro audio related technical discussions

www.speakerplans.com/forum

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Eyup,

although I've been a mobile dj for about a million years, I've never tried bi-amping before & I could do with some advise. I've recently acquired some more gear and so here is what I've got to play with:

Gemini GX 400 speakers, D-Class CD15N Bins

3 amps: Kam KXR1500, Kam KXR1000,Synq Dig3K6

Kam KX050 Crossover, Kam KEQ152 Graphic and a BehringerVMX100 mixer (which also has an adjustable mono output for subs)

Any advice on matching amps & speakers and also wiring it all up would be gratefully received. Thanks (in advance) Deano

:dukesy: Cheers, all.

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