active crossover(make or buy one?)

ShinAce

I have my breadboard sitting here with the left channel of a second order L-R crossover ready to go(2-way).

I can whip out another LM1458 and get the right channel going, then I thought I can probably buy an adjustable x-over cheaper than I can build one.

I found:
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=245-862

$ 100. Variable 2 way crossover with sub output. I do not need a sub output as my subamp has a built in variable crossover section. This premade xover is 24 dB/oct to boot.

Should I continue building the one I have now(get some connectors), or just buy the ART x-over? Anybody have experience with these or ideas on making an electronic xover adjustable on the cheap(no switches, bi**hes).

Systems

I seen that Art unit and it looks like a good for the money but I think I would opt for the Behringer CX2310 instead.http://www.behringer.com/CX2310/index.cfm .I have read several good reports about it and its even cheaper.:D


I have built actives on perfboards but by the time you add up the cost of chassis, power supply connectors, etc. it may end up costing more than the Art or CX2310.

Early B.

Sid is not too keen on most Behringer gear, but I'm interested in his thoughts on the build quality of the CX2310.

Sid?

ben62670

Don't forget those Pro Actives are balanced, So don't forget the adapters. I know this isn't going to get much applause from the audience, but you can get a car audio old school Alpine for $50-$80, and have a great XO. Add a 12v wall wart, and you are done. I have done this just to play around to decide where I want to build my passive XO's at, and the performance was stupendously impressive. BTW I know wall warts get a bad rep, but an auto XO is designed to deal with ugly power.

Systems

Early B. wrote: »

Sid is not too keen on most Behringer gear, but I'm interested in his thoughts on the build quality of the CX2310.

Sid?

Who 's Sid?I had my doubts about Behringer as its Chinese made (though German designed).A gentleman on another forum uses one (CX2310)to add subs to his Magnepans.He compared it to a higher end unit with premium op amps and passive parts and said the Behringer sounded just as good.I have read other good reports about this specific unit as well.IMO for $89 I think either the Behringer or the ART units would be much preferable to the perfboard DIY construction.If going the DIY route I would snag some PC boards from Marchand or Linkwitz Labs.

If you want to get serious buy one of these.http://www.bryston.ca/10b_m.htmlI use one of the 10LR 's.

Early B.

$89, you say? Wow. Let's build some speakers that use a active crossover. I'll start another thread for it.

Systems

Early B. wrote: »

$89, you say? Wow.

Yep but don't expect Krell build quality.:D

Let's build some speakers that use a passive crossover.

don't you mean active?
Im using currently using a DIY pair of active speakers.

ben62670

I like active. No worries about difficult impedance curves. No worries about which caps, and inductors, and resistors. Independent level adjustment. Only downfall I have had is 2 amps for 2 ways. I do however recommend a cap to protect the tweeters with a 6db slope 250-500 hz below the HP point.

Face

What do you do about peaks?

Systems

Face wrote: »

What do you do about peaks?

If the peak has a fairly narrow bandwith such as the break up mode in a metal woofer cone ,then you could use an active notch filter tuned to that specific frequency.But this this would only be possibile with a custom DIY active xover as commercial units don't have notch filter options.

The best approach is to use drivers that have smooth response to begin with so that you don't have nasty peaks to deal with.

jakelm

GV#27 wrote: »

If the peak has a fairly narrow bandwith such as the break up mode in a metal woofer cone ,then you could use an active notch filter tuned to that specific frequency.But this this would only be possibile with a custom DIY active xover as commercial units don't have notch filter options.

Or passive XO such as what Polk uses.

The best approach is to use drivers that have smooth response to begin with so that you don't have nasty peaks to deal with.

+1

Ben and I both know why some XO's are so complex. And its not because of a complex system. Its because of cheap drivers. So your best bet, in any DIY design, is to choose good drivers. A good enough driver, wont need but 1 inductor, 1 cap and maybe a resistor or 2.

Face

My current speakers have 6 caps, 5 resistors, 2 inductors, and a autoformer per crossover, scratch that idea.

jakelm

Face wrote: »

My current speakers have 6 caps, 5 resistors, 2 inductors, and a autoformer per crossover, scratch that idea.

It depends on the speaker smart **** I mean Face!!:rolleyes::p

ShinAce

The Behringer appears to have balanced inputs only.

To provide more info on the DIY route. I have caps, I have resistors, I can etch the board. I even have a spare chassis and the parts to build a regulated dual rail power supply. The only thing I will need to buy will be RCA jacks and possibly new value caps+resistors. It's the labor that will run me $ 100 worth.

Systems

ShinAce wrote: »

The Behringer appears to have balanced inputs only.

Yes but you only need a few 1/4" to RCA adaptors to rectify that.part #090-285 in pe catalog.

To provide more info on the DIY route. I have caps, I have resistors, I can etch the board. I even have a spare chassis and the parts to build a regulated dual rail power supply. The only thing I will need to buy will be RCA jacks and possibly new value caps+resistors. It's the labor that will run me $ 100 worth.

Well if you have all these goodies then DIY ing might be the way to go.I have built a few actives from scratch so if I can be of any assistance I would be glad to help.I have a listing for parts values and xover frequencies for 4th order LR 's so I can save you some math.

ShinAce

The test setup I still have not tried out is using 0.1 uF caps and 470 ohm resistors for a crossover frequency just a bit above 3K. It is a 2nd order Linkwitz-Riley.

I will probably proceed with the home-made one and upgrade the opamps to NE5532s if it works well. I already have a 15-0-15 volt transformer (200 mA), 100mA regulators(78l12 and 79l12), chassis and copperclad board.

I'm also getting a bonus from work in March that I may use to buy a new amp and the crossover. I was planning on using an older stereo receiver to power the tweets for this test.

jakelm

I refuse to subject myself to a 4th order xover. If you cant get by with a 2nd order xover, then buy better drivers...:p:D

ShinAce

I wouldn't mind using a 4th order, but that's just gonna add parts that I don't need. My goal is to test out the performance difference between the passive crossover and active crossover with all other specs the same. I'd also be a bit paranoid of the 4th order not meeting exactly at the crossover point and causing unwanted dips or peaks. More parts and they have to be precision? Nuts to that.

I'm pretty sure that a 4th order is good for phase response.

Systems

jakelm wrote: »

I refuse to subject myself to a 4th order xover. If you cant get by with a 2nd order xover, then buy better drivers...:p:D

Some very good speakers(with excellent drivers) use 4th order xovers such as Linkwitz's Orion,Aerial,Snell,Revel,KEF and several others.While the steep rate of attenuation can be benificial in reducing problems in a drivers response there is more to it than that.Other benifits include reduced lobing and off axis response problems,the tweeter will be afforded higher power handling and less distortion.

Systems

ShinAce wrote: »

My goal is to test out the performance difference between the passive crossover and active crossover with all other specs the same.

That should prove to be an interesting comparison.;)

I'm pretty sure that a 4th order is good for phase response.

Yes if it is designed correctly the drivers will be exactly in phase.

ShinAce

GV#27 wrote: »

Other benifits include reduced lobing and off axis response problems,the tweeter will be afforded higher power handling and less distortion.

To add to this comment, I must point out the fact that an active crossover isolates the drivers. If the woofer amplifier is driven to clipping, no distortion should find its way to the tweeter. This dramatically increases the lifespan of the tweeter. This also means tube amps can be used more freely when combined with active crossovers.

I love active but I must admit, I am afraid. What am I afraid of? I don't know.

Okay, so when I get some time, I'll check the crossover I am building for correct operation(12 dB slope at the correct cutoff fre), harmonic distortion, phase(polarity in this case) and bandwidth. Once that is done, I build the real thing. Once that is built, I will buy the ART xover and compare its 24 dB versus my 12 dB slope.

The woofer is a Pioneer C16LU20-51F. The tweeter is the Audax TM025F1. Resonance of the tweeter is at 1,090 Hz and it handles 60 WRMS. I don't expect to have to baby this tweeter. I will start with the xover at 3-4 KHz and work my way down to 2 KHz if I can.

It's too bad I gave away my scope. I might just have to make one for PC.

ShinAce

GV, do you know if I need to reverse tweeter polarity on a 2nd order 2 way active?

I no longer have a scope so I can't really test polarity that well. Listening only.

Systems

ShinAce wrote: »

GV, do you know if I need to reverse tweeter polarity on a 2nd order 2 way active?

Theoretically yes ,but other factors play a part and you may well find that the drivers will sum together better with normal polarity connection.

How close the crossover point is in relation to the natural rolloff of the tweeter and woofer will affect the phase relationship between the two.As well if drivers are mounted together on a flat baffle(ie not slanted backwards to time align them)then the tweeters acoustic center will be closer to the listener than the woofers.This will also alter the phase relationship between them. So it depends ,try both ways and compare,the wrong polarity should be audible, imparting a hollow sounding character to the midrange.
If you have an SPL meter and some test tones then you could verify it that way.

Joe08867

I have two of the Behringer crossovers for my PA System. I use them in a three way setup. Highs (Compression Drivers) Mids-Midbass(8" Mid Driver or 12" Driver) and Subs (18" Yamaha Sub x 2) It works quite well. And at $89.00 it is pretty darn cheap.

I have found the Behringer stuff to be pretty good overall. Not the sturdiest but decent sound. No it isn't the best stuff out there but for the price it is hard to pass up. I would never use there Amplifiers though. Very thin sounding. Sorry gone off track.

ShinAce

I tried out the active I built, but it turns out I've got an intermittent connection somewhere.

Once I get it debugged, I'll be back.

soiset

I've had great results with the used Rane AC-22's I've used. Very solidly built, very adjustable. The sound is significantly improved over passives. You can get them for about $70-80 on ebay. Except for the need for a second amp, I can't see why anyone would DIY speakers with passive crossovers.

ShinAce

Cost and simplicity. Passives are a one and done.

Actives just seem to be so much more fun and better performing.

soiset

Forgot to mention: make sure you use a high value cap in line with the tweeter to protect against amp thump. I use some 27 uFarad dealies. They don't affect the sound.

ShinAce

The amps have a delay mute when turning on, I don't know about turn off though.

soiset

ShinAce wrote: »

The amps have a delay mute when turning on, I don't know about turn off though.

At the least, it's cheap insurance against a blown (and expensive) tweeter.