Using A Active Crossiver With Speakers That Have A Built In Crossover

[Dan allanthemsdisco 0]

Hello Dj friends!!

I am wondering, if i am using a active crossover, but my speakers have crossovers in them, will this reduce quality / loose power output?

I am also wondering if a surge protection plug strip adapter will be a good idea in the disco context. IE will it cut everything out if the amp suddenly draws loads of current when the bass comes in? Sorry if it sound stupid but i want to be sure there is no disadvantage or risk of loosing power if it cuts everything out for no reason!!

Many thanks

DJ Dan -Wishing he was DJing!! instead of staying in

[superstardeejay 0]

First of all the surge protector sockets. They protect the equipment from voltage surges caused by 'spikes' or 'overvoltage' on the mains incoming. They contain components that 'clamp' any momentary spikes, and blow completely (and cut off the power) if the mains rises to a dangerous level for a prolonged (more than a few milliseconds) period. Either way, they protect your equipment..or are supposed to.

 

They arent affected by the current drawn from the outlets so a bass note wont affect them.

 

Your active crossover is designed essentially to split frequencies between cabinets to allow bi-amping (using two amps) for say a pair of bass bins and a pair of mid-high (top) cabs, unless you have very elaborate tri-amping plans which i doubt. The top cabs will have their own passive crossover to split the signal again between the woofer and tweeter (if so equipped) and this should be left alone and in-situ. The Bass cabinets may well have a low-pass crossover which causes the bins to react mostly to the music at which they are the most efficient, and it will have been designed with the cabinet and driver in mind. Purists say you ought to remove this crossover if you have an electronic external one; in reality though, you can leave it in since the cabinet is unlikely to give much better response outside of the frequencies it was designed for and your new electronic crossover will simply enhance it further.

 

 

[Bouncy Dancefloor 0]

in addition to superstardeejay, i would say bypass the internal crossover in the bass speakers. I read a report which said that if you pump 500watts into a bass cab, due to the physical crossover, you are only getting approx 400watts of bass being produced, if you bypass the physical crossover in the cab and use the Active one, then you get a pure 500watts of bass , at the frequencies you require

[Dan allanthemsdisco 0]

in addition to superstardeejay, i would say bypass the internal crossover in the bass speakers. I read a report which said that if you pump 500watts into a bass cab, due to the physical crossover, you are only getting approx 400watts of bass being produced, if you bypass the physical crossover in the cab and use the Active one, then you get a pure 500watts of bass , at the frequencies you require

 

This makes sense, as i know the reason an active crossover is used it because a passive one is not powered and so it causes loss of power but wanted to double check here. Why is it that speakers dont have a input for both i dont know.

I suppose if i wish to ill have to unscrew the speakon panel, bypass the crossover and that will do it, just a matter of time now, but i know i want the best sound possible so i probably will do it.

Thank you fboth for your replies & once i know that surge protector power strips are not a problem i will be incorporating them.

Thanks again!!!

 

[TonyB 0]

First thing I do when I get a pair of bass bins is take the passive crossover out. I usually listen to one with and one without to see how much difference it makes and usually it is noticeable. The driver gets the full damping effect from the amp without the passive crossover and they do need less power to drive them.

[Dan allanthemsdisco 0]

brilliant info guys thanks. Im gonna remove mine because at the end of the day its an active system and that should not be hindered by a un needed crossover. Hopefully this will be useful to many others.

 

[TonyB 0]

I would emphasise that I only take them out the bass bins. Taking them out of the tops can cause damage to the tweeter. I have one set up that doesn't have passive crossovers in the tops but they have high pass filters for the tweeter.

 

Also be careful of the power you push into speakers without passive crossovers as they often provide protection against being overdriven. A limiter would be a good idea.

Edited April 12, 2009 by TonyB

[superstardeejay 0]

if you pump 500watts into a bass cab, due to the physical crossover, you are only getting approx 400watts of bass

 

This isn't how crossovers work. If this was the case, you'd be losing 100W of power in the cabinet somewhere!!!

 

Passive crossovers simply alter their impedance so that frequencies from the amp that are out of the range of the crossover just cause the cabinet to increase its overall impedance and the speaker stops drawing so much power. This increases the efficiency of the speaker and puts less strain on the amp, allowing you to push it harder.

 

I re-iterate, I wouldn't bother opening up the bass bin and ripping out the passive crossover..at least not for the power levels used by the average mobile disco.

Some larger speakers do have either a crossover bypass switch or seperate socket for direct connection but it's rare.

 

 

 

 

[TonyB 0]

Power loss caused by passive crossovers is called "insertion loss" and is typically around 20%. A Goole search for "passive crossover insertion loss" and "passive crossover damping effect" will explain the effect a passive crossover has on sound quality.

[milhouse 0]

in addition to superstardeejay, i would say bypass the internal crossover in the bass speakers. I read a report which said that if you pump 500watts into a bass cab, due to the physical crossover, you are only getting approx 400watts of bass being produced, if you bypass the physical crossover in the cab and use the Active one, then you get a pure 500watts of bass , at the frequencies you require

 

Agreed. I have a Mackie S218s Bassbin, that (had) an internal crossover. It was housed in a nightclub.

 

Initially we fed a full signal into it from an amp. The bass bin sounded ok, but I felt it wasnt putting out its potential volume, it just did not sound right. Eventually the internal crossover actually fried itself, and the unit stopped working.

 

So I opened up the unit and ripped the crossover out. I wired the cone directly to the cables coming into the back of the unit, and used an active Phonic crossover before the QSC amp.

 

And boy does it sound different - much better quality sound and the bin is performing well. The difference in reproduction of lower bass is superb.

Edited April 14, 2009 by JonWhittaker

[Kingy 0]

Agreed. I have a Mackie S218s Bassbin, that (had) an internal crossover. It was housed in a nightclub.

 

Initially we fed a full signal into it from an amp. The bass bin sounded ok, but I felt it wasnt putting out its potential volume, it just did not sound right. Eventually the internal crossover actually fried itself, and the unit stopped working.

 

So I opened up the unit and ripped the crossover out. I wired the cone directly to the cables coming into the back of the unit, and used an active Phonic crossover before the QSC amp.

 

And boy does it sound different - much better quality sound and the bin is performing well. The difference in reproduction of lower bass is superb.

 

I have to ask....why do you think Mackie go to the expense of installing that cross over then if it could be just hard wired to an amp?? Surely it is there to limit the frquencies that those drivers and that cab can utilise??

[TonyB 0]

I have to ask....why do you think Mackie go to the expense of installing that cross over then if it could be just hard wired to an amp?? Surely it is there to limit the frquencies that those drivers and that cab can utilise??

 

I think you missed the bit that said "...and used an active Phonic crossover before the QSC amp" i.e. it wasn't hard wired to an amp but via an active crossover. They probably didn't got to a lot of expense as a quality passive crossover would cost as much as an active one. Instead cheaper components are used that are "adequate" to split the sound between highs and lows.

 

The power loss is in the form of "heat" and as Jon mentioned, when too much heat is created, it can fry the crossover.

[superstardeejay 0]

Y'know a basic passive low-pass crossover usually consists of an inductor in series (and possibly a capacitor in parallel) with the bass driver. The impedance of an inductor increases (and a capacitor decreases) with the frequency of the signal. This impedance change is known in the trade as 'wattless' because, unlike a resistor, inductors and capacitors dont dissipate energy in the form of heat. The big resistors in a 2-way passive crossover are there to limit the power supplied to the tweeter and it is this part that can overheat if the cabinet is overdriven..or the capacitors that split due to overvoltage for similar reasons. A passive low-pass crossover dissipates little heat at all apart from the slight volt-drop in the coil. By the time this thing melts, you're usually well on your way to frying the driver anyhow.

 

A Goole search for "passive crossover insertion loss

 

I did this and came up with this (first hit)

 

The most significant power loss occurs with low-pass filters, since their key components – inductors (see below) – incorporate many turns of wire that have a small but measurable DC resistance. This resistance will reduce the amount of power delivered to the speaker, but in most cases it is not significant.

 

As far as disco speakers are concerned, the DC resistance of a low-pass filter is measured in fractions of milli-ohms...considerably less than the speaker leads that connect the cabinet to the amp!

 

 

 

Edited April 14, 2009 by superstardeejay

[Kingy 0]

I think you missed the bit that said "...and used an active Phonic crossover before the QSC amp" i.e. it wasn't hard wired to an amp but via an active crossover. They probably didn't got to a lot of expense as a quality passive crossover would cost as much as an active one. Instead cheaper components are used that are "adequate" to split the sound between highs and lows.

 

The power loss is in the form of "heat" and as Jon mentioned, when too much heat is created, it can fry the crossover.

 

No I didn't.

Surely it goes Mixer-crossover-amp-speaker and therefore the speaker is directly across the (uncontrolled) output of the amp. The active crossover would be pre-amplifier surely.

[TonyB 0]

No I didn't.

Surely it goes Mixer-crossover-amp-speaker and therefore the speaker is directly across the (uncontrolled) output of the amp. The active crossover would be pre-amplifier surely.

Yes you are correct, I was having a senior moment :)