Active bi-amp - Which electronic crossover?

[rhapsodee]

Hey guys,

I have been thinking of trying out active bi-amp, currently have a passive bi amp system.

However, don't seem to be a lot of options on how to go about doing so? I will need an active electronic crossover, but there are not many available in the hi-fi market. I am aware of some pro-audio active crossovers, and also read about some DIY projects.

What would be the best way to get started? Not too keen on DIY, think will be too much for me at this point.

Thanks and appreciate the advise.

[Dr.EM]

This:

http://sound.westhost.com/project09.htm

may make a nice starting point, though there is often more to a practical crossover system. Read here for more details:

http://www.linkwitzlab.com/filters.htm


What speakers are you using? Presumably commercial ones with built in crossovers? Bear in mind you'll have to by-pass these to take advantage of an active setup and that without driver responses, designing a suitable crossover will be very difficult to do well. There is the possibility to make the existing crossover as an active unit though

[Moondog55]

Use a cheap pro-audio unit to start with, put a query in the trading post section for a Behringer CX 2310.
Do an online search for the item and you will find a lot of opinions on this unit, I use them and I'm happy ; so long as I keep the XO frequency below 250/300 Hz i can't hear the noise and distortion claimed by some users
Here in Melbourne they go on sale for AUD$99- every now and then, paid that for my last unit.

Good way to get your feet wet for relatively cheap price, then you can go on the buy or build good quality units if you need to.


Regards

[rhapsodee]

Dr EM: Thanks for the links. I have read the westhost site before, that was the main reason that got me interested in active crossovers. Actually i was planning to use the Recession Kit for the mid+high, and another set of dual 6 or 8 inch woofers for the low. Planning to use the active crossover at 250-300Hz for this.

Am rather intimidated by the option of DIY for my first project though.


Moondog: Thanks for the link on the Behringer. Unfortunately, i don't think they are easily available in Singapore. I have also come across an Ashly pro-audio crossover. However, they all seem to use balanced or XLR connectors. how would i connect that to home audio RCA plugs?

What about the Reckhorn S-1 as an electronic crossover for the 250-300Hz split between the woofers and the recession buster kit?

Another side question, would i have to remove the baffle step correction in the recession buster crossover, since i am only using it to about 250-300Hz?

Oh, the woofers will go down to about 60 Hz, will also be having an active sub, using the O Audio plate amp.

Thanks!

[Mr Evil]

A basic active crossover is very easy to build, it will be fine as a first DIY project. You can literally put one together on a breadboard in a couple of minutes.

[eplpwr]

When you've tried bi- or even tri-amping with a decent filter, you'll never go back to passive again.

It simply sounds better. Much, much better.

I was inspired by Rod Elliott and I think his no-nosense writing is what got me on track. After a lot of work with DIY speakers and low-level electronics (preamp / XO) I was in for my first listen. After a couple of seconds of listening I was completely sold on the concept of active crossovers / multiple amps. It literally rocks!

[Drew Eckhardt]

Originally posted by Dr.EM
[B]This:

http://sound.westhost.com/project09.htm

may make a nice starting point, though there is often more to a practical crossover system. Read here for more details:

If you're going to DIY something permanant:

Siegfried Linkwitz sells boards with better topologies (notch filters, shelving filters for baffle step/dipole/driver equalization, all-pass for phase alignment), tweaks to avoid RF problems (low-pass filters for RF on the input and op-amp feedback loops), proper power supply decoupling at the op-amps, etc.

They're dead quiet (at least the Phoenix boards which evolved to the ASP and Pluto boards).

The ASP boards allow for a 3-way with out-board amplification:

http://www.linkwitzlab.com/pcb.htm

The Pluto boards are 2-way with an LM3886 for one channel and bridged LM3886s for the second:

http://www.linkwitzlab.com/Pluto/supplies.htm

A solderless breadboard will do for prototypes.

[Moondog55]

Almost all pro crossovers use Cannon (XLR ) balanced connectors, however an XLR to RCA cable is very easy to make, just involves a small cable bridge from shield to common/earth.

[gainphile]

If you are experimenting, then breadboards are the way to go.

Cost only about $10 and you can pretty much do anyting quickly.




That picture is 3-way, 24db/oct xo.


If this is your 1st time, build a 12db LR. Only need 3 TL072 op-amps for a two-ways. 1 buffer and 2 for the actual xo.

Then move on to 24db/oct.

Download the calculator tool from this link. It's a real time-saver.

http://sound.westhost.com/project09.htm

[MJK]

I am using a dBx DriveRack PA active crossover which you can find at Parts Express or on E-Bay. It will handle two or three way set-ups, has independently adjustable slopes and crossover frequencies, it has EQ, and you can boost or cut the levels to the different drivers. It is a very powerful crossover that can be adjusted on the fly to dial in the sound of your system. It does use XLR connectors and cables which is no big deal for me since my preamp and amps have that option. Once you get the hang of it, it is really easy to use.

I think the Behringer DCX 2496 does a lot of the same things but has an additional advantage of a computer interface that can be used to program the adjustments. Being able to sit in your listening spot and adjust the crossover to dial in the sound of your system would be a real advantage.