Need Help Choosing An Active Crossover

CJWessing

Standard Member
Hello,

I have a pair of Kef XQ5's that I'd like to bi-amp, but I'm having trouble finding many active crossovers out there. Can you please recommend some active crossovers that I should be looking at? There doesn't seem to be many options.

The low frequency crossover on my Kef's is 300Hz, so I'd like to find a crossover that can provide a setpoint of 300hz.

The only one that I've found so far is a Dahlquist DQ-LP-1 which can be set from 40-400Hz, but they are a bit expensive (~$400).

Thanks,
Chris
 

alexs2

Distinguished Member
Hello,

I have a pair of Kef XQ5's that I'd like to bi-amp, but I'm having trouble finding many active crossovers out there. Can you please recommend some active crossovers that I should be looking at? There doesn't seem to be many options.

The low frequency crossover on my Kef's is 300Hz, so I'd like to find a crossover that can provide a setpoint of 300hz.

The only one that I've found so far is a Dahlquist DQ-LP-1 which can be set from 40-400Hz, but they are a bit expensive (~$400).

Thanks,
Chris

Firstly,I'll say this.........This idea wouldn't be my choice of solutions for biamping or anything like that,and I have had a couple of fully active systems previously.

As far as I know,the Q5 is bi-wireable,so by removing the bridging links you would be able to use 2 separate amps,one for the bass and the other to cover the upper ranges,but you would need to confirm this either with KEF or by your manual.

Finding,and setting up a suitable active crossover is not the simplest task....there are a good number of relatively cheap and cheerful devices aimed at the pro-market but whilst cheap,most will not be of a good standard.

The Behringer model is likely to be the best cheap solution at around £80-90 but you will need to disconnect your speaker's internal crossovers and replace the relevant wiring,before even starting on the job of frequency and level matching the drive units.
The Behringer offers variable frequency,slope and delay to give a degree of phase correction also.

http://www.behringer.com/CX3400/index.cfm?lang=ENG

Your Kef has bass,mid and HF crossover points to be set,plus the slope and level for each.

You would need to be able to accurately measure the frequency response at the very least with a decent real time analyser,an accurately calibrated microphone and a good room,otherwise you could easily end up with something that sounds awful.

In the higher price bracket Bryston make a very versatile one as well,but I don't think this will be anywhere near your chosen price level.
 

CJWessing

Standard Member
Thanks for the reply, Alex. I wasn't planning to replace all of the crossovers in my speakers (300hz, 3khz, 15khz). I was just planning to remove the connection between the binding posts on the back, and then run low frequencies to one pair, and highs to the other pair. This would essentially remove the 300hz crossover, but keep the upper two crossovers to protect the tweeter and hypertweeter. Then all I'd need is a simple stereo 2-way 300hz active crossover, right? Or would I still need to remove some crossovers/filters/wiring inside the speaker?

Here's the Dahlquist I'm looking at:
AudiogoN ForSale: Dahlquist DQ-LP1
 

alexs2

Distinguished Member
Thanks for the reply, Alex. I wasn't planning to replace all of the crossovers in my speakers (300hz, 3khz, 15khz). I was just planning to remove the connection between the binding posts on the back, and then run low frequencies to one pair, and highs to the other pair. This would essentially remove the 300hz crossover, but keep the upper two crossovers to protect the tweeter and hypertweeter. Then all I'd need is a simple stereo 2-way 300hz active crossover, right? Or would I still need to remove some crossovers/filters/wiring inside the speaker?

Here's the Dahlquist I'm looking at:
AudiogoN ForSale: Dahlquist DQ-LP1

If you plan on simply removing the bridging link,then you would not need external crossovers.
 

CJWessing

Standard Member
The point of the external crossover (active) is to split the frequencies prior to the amplifier, right? Would anything be gained by using a active crossover, bi-amping my kef's by simply removing the bridging link on the speaker?
 

alexs2

Distinguished Member
OK....the advantages of an active crossover are...

1.Greater overall efficiency as there are no power losses in a passive crossover.

2.The ability to tailor the crossover points and slopes very accurately(although this can be achieved with passives as well).

3.The ability to adjust phase response.

4.Ease of adjusting bass/mid/treble levels independently.


The disadvantages are cost,need for several amplifiers,and time in setting up properly,plus the need for a speaker system suitable for active use.

Personally,I would say that implementing an active croosover system from scratch is quite an undertaking if you want to get it right.

KEF will have spent quite a while tailoring the passive network in your speakers,and with considerably greater resources.

I had 2 fully active Linn systems prior to making the move back to a passive crossover system......there is no doubt that done properly,an active system can have superb transient response and with suitable amps,a very large headroom available,but it is a costly solution.
 

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