Looking to replace Basic Passive Crossover

K

Kip Conner

Junior
Mar 13, 2011
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Athens, GA
I have several floor monitors (15" & 1.5") that I am thinking about replacing the crossovers when I put them back in passive mode. As a back story I took the crossovers out and mounted them in aluminum project boxes from Fry's to make for easy Bi-Amp to Passive applications. The monitors don't get much use and when they do they seem to go in the passive form these days.

I'm looking for some inexpensive crossovers that are passively crossed around 1600 cycles and pass roughly 300 watts.

By inexpensive and I don't mean cheap... thoughts?
 
Re: Looking to replace Basic Passive Crossover

Kip Conner said:
I have several floor monitors (15" & 1.5") that I am thinking about replacing the crossovers when I put them back in passive mode. As a back story I took the crossovers out and mounted them in aluminum project boxes from Fry's to make for easy Bi-Amp to Passive applications. The monitors don't get much use and when they do they seem to go in the passive form these days.

I'm looking for some inexpensive crossovers that are passively crossed around 1600 cycles and pass roughly 300 watts.

By inexpensive and I don't mean cheap... thoughts?
Click to expand...

First thought would be to read this thread, particularly the part about passive crossover design.

Mac
 
Re: Looksgto replace Basic Passive Crossover

As Mac hints, what you want is not going to be easy. There is no off-the-shelf crossover that is going to work properly with your specific driver and box. In fact, as that thread mentions, even variations between the same driver will mess things up.

The cost of developing and building a passive crossover to work in your boxes will probably make new speakers look like a better option...

Why would you want to replace the existing crossovers? Something wrong with them?
 
Re: Looksgto replace Basic Passive Crossover

They work fine other than them having a gnarly phase shift that occurs from 2k to 4kHz, which by all means isn't a big deal since the shift doesn't propose any trouble to the crossover point. I figured if I was going to spend the time resoldering these guys back in to the boxes that there might an upgrade that I could get at a reasonable price. The manufacturer of the box is located here in town and they might have something that I could stick in there. Everything that I own is bi-amped for obvious reasons so I just wasn't sure if there was a basic crossover out there that could be purchased based on various speaker specifications. Something like this generic piece...

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=290-634

I couldn't tell you if this qualifies as cheap or inexpensive since I have never purchased anything like it before.
 
Re: Looksgto replace Basic Passive Crossover

Kip Conner said:
They work fine other than them having a gnarly phase shift that occurs from 2k to 4kHz, which by all means isn't a big deal since the shift doesn't propose any trouble to the crossover point. I figured if I was going to spend the time resoldering these guys back in to the boxes that there might an upgrade that I could get at a reasonable price. The manufacturer of the box is located here in town and they might have something that I could stick in there. Everything that I own is bi-amped for obvious reasons so I just wasn't sure if there was a basic crossover out there that could be purchased based on various speaker specifications. Something like this generic piece...

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=290-634

I couldn't tell you if this qualifies as cheap or inexpensive since I have never purchased anything like it before.
Click to expand...

The gnarly phase shift is possibly a peak from the woofer that's coming through out-of-band (or supposedly, who knows where the acoustic crossover is) and interfering with the HF driver. Of course, it's not easy to phase align a box with a passive crossover. This is where all that expensive R&D comes into play.

Something like, maybe:
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Re: Looksgto replace Basic Passive Crossover

Silas,

You seem to know an awful lot about the phase performance of a box that we haven't seen a measurement for. Since when is Gnarly an internationally accepted unit of measurement? Your 5dB response peak (and I'd be willing to bet my car the driver doesn't measure like that in real life) is surely not causing phase shift on the order of "gnarly".
 
Re: Looksgto replace Basic Passive Crossover

Of course he's quoting me on the Gnarly thing, in reality the shift occurs in the portion of the display that reverses in a typical 2-3way system. The shift is a 90 degree turn between 2-4k occurs in an otherwise 45 angular degree leading trace. These are times that I wish I was smart with an oscilloscope and I could give better descriptions. The description above is based on the law of averages between the original stock and a known flat(ter) response 2-way speaker system from Berkeley. I understand it's not a great way to get results, but it's there.

I'm not looking to do anything more than to go passive with these boxes since they are being used for a cover act that can't pay for anything else. While I take enough pride in my work to give them the better bi-amped option and I can't take the financial liability on sending out omnidrives and more amplifiers, not to mention the weight of a bi-amped rack. I'll send the 12am's when they are ready to pay for them! Until then, they get these fabulous mid 90's OAP 15" cabinets from the C System.
 
Re: Looksgto replace Basic Passive Crossover

Kip,

Buy some cheap powered plastic boxes. Proper passive crossover design is way more difficult than proper active crossover design, which is not exactly kid stuff.

Silas should know better than to come here and spout nonsense. Since I know him and not you, I was making fun of him and not you. The phase shift you observe is probably due to the crossover.
 
Re: Looksgto replace Basic Passive Crossover

Kip Conner said:
Until then, they get these fabulous mid 90's OAP 15" cabinets from the C System.
Click to expand...
If OAP designed the crossovers for the speakers, they will probably be better than anything you can buy "off the shelf".
The minor problems you have mentioned could require an additional half dozen parts in a passive crossover to fix.

Generic passive crossovers are usually designed considering the drivers as a resistive load, when used with real speakers, the acoustic crossover can be an octave (or more) off with bizarre slopes, which may offer little protection for the HF driver.

Design of a proper passive crossover starts with the specific parameters of the drivers, horns and orientation, and ends with testing of those components with real capacitors, inductors and resistors, and substituting parts until the acoustic results match the desired slopes.

Art Welter
 
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