AudioCircle
Audio/Video Gear and Systems => Enclosures => Topic started by: mix4fix on 26 May 2023, 12:56 am
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https://www.parts-express.com/speaker-components/crossover-components/assembled-passive-crossovers
When it comes to pre-made passive crossovers, which brand would you use from Parts Express?
Dayton?
Parts Express?
Eminence?
PRV?
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Do you choose by brands?
I have seen people who choose by price.
Some are two way other three ways.
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I'm talking about brands as build quality, or how it sounds.
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Two way are preferable over three ways,
air core are better than iron cores or reels.
These crossovers are all different.
What freq cuts do you need?
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There's more to crossover design than just the crossover freq.
A drivers' impedance curve affects the crossover filter's output function, so the parts need to be custom selected to match the driver to create the desired acoustic roll off.
Two different midrange drivers will need different crossover parts to achieve the same filter function on the acoustic output, because of the different load impedance curves and different frequency response curves of different drivers.
Making two drivers blend together is more than just picking xo frequency, they must also sing together in time to avoid phase cancellation and crossover has a big part in that phase coherence because the slope of the filter changes the rate of rotation of the phase per freq.
The box size and shape also affects the diffraction frequencies and bass extension and thus the crossover design.
None of these aspects are considered in the premade crossovers, unless they specify the speaker the crossover is designed for. It's really a sucker play, offer for sale the hard part of speaker design that most hobbyists don't know how to do, so they feel confident to buy the expensive drivers. But it will sound bad.
Sometimes sounding bad is OK as long as it's cheap, like garage band PA monitors or GenZ beach boom box/drinks cooler. Parts express is not just for audiophiles.
Not to sound snobby because I'm very frugal, but I do have a good ear and I must normally spend about the same money on a single good tweeter cap as those whole premade crossovers cost. They are made with very cheap parts that sound bad by audiophile standards. But the filters function correctly on a frequency response curve even with cheap parts, and the price is right. But not intended for audiophiles.
It's fine to buy a premade crossover that's intended to work with specific speaker design - say as part of a kit, or as an upgrade to replace the stock crossover in a certain commercial speaker. But usually the crossover is custom designed towards the end of the design process to make the rest of the speaker parts work together to sound good. A designer may even start out with certain crossover ideals as design criteria, like 1st order slopes, or minimal parts count, or no resistor on the tweeter, and then design the speaker around those ideals, but the parts values will be chosen by ear or by computer simulation after the rest of the speaker is assembled and measured. Pretty much impossible to do it backward, choosing drivers and box to match a premade xo.
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This is just playing around with pair(s) of crappy speakers. It will never sound good no matter what expensive parts get used.
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The Dayton polyproplene caps are decent. If the 2 way xo is higher, they are polyproplene. For the lower xo frequencies they tend to use electrolytic. All the parts express XO look like they use electrolytic caps. For a cheap speaker project I would choose the Dayton Audio. That said, you could likely rebuild the XO you have in the speakers for about the same price using similar or better spec parts.
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It looks like buying the matching seperate high pass and low-pass would be cheaper than the two way. Thoughts?
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This is just playing around with pair(s) of crappy speakers. It will never sound good no matter what expensive parts get used.
:thumb:
It looks like buying the matching seperate high pass and low-pass would be cheaper than the two way. Thoughts?
The two way xo is just two separate filters in parallel on same board. You would wire two separate boards in parallel anyway so it would be electrically the same as two way board. Whichever fits best or convenience.
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Any impedance issues?
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Inserting a random crossover into a speaker is like inserting a random piston into an engine.... it's not going to work. If you already have the drivers, do a search to see if there might be someone's DIY plan for them.
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Any impedance issues?
Two main issues related to impedance:
1. If your drivers are low impedance and wired in parallel through the premade xo they might offer an impedance that is too low for your amplifier. A well designed custom xo avoids low impedance to the amplifier.
2. The load impedance on the crossover filter determines the filter's output function.
Example: the same crossover filter on an 8 ohm driver will roll off at a different corner frequency than on a 4 ohm driver. And driver impedance is a curve that varies with frequency on any driver. A custom crossover can flatten the load impedance of a driver so the filter will function as expected, but a premade xo has no impedance correction.
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Two main issues related to impedance:
1. If your drivers are low impedance and wired in parallel through the premade xo they might offer an impedance that is too low for your amplifier. A well designed custom xo avoids low impedance to the amplifier.
2. The load impedance on the crossover filter determines the filter's output function.
Example: the same crossover filter on an 8 ohm driver will roll off at a different corner frequency than on a 4 ohm driver. And driver impedance is a curve that varies with frequency on any driver. A custom crossover can flatten the load impedance of a driver so the filter will function as expected, but a premade xo has no impedance correction.
I meant using seperate high and low pass filters versus the two-way.
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No difference wrt impedance, separate or 2way
All things being equal, the 2way filters are wired in parallel on the same PCB.
The single filters are stand alone on their own PCB, but you wire them together in parallel.
Electrically same circuit.
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One of the pairs being worked on is a budget speaker kit I received with parts missing. I bought missing drivers to complete the assembly. The crossover point is around 1600Hz. I'm like OK: 1600HZ for those, and another 1600Hz, 1800Hz or 2000Hz for the other pairs to keep it simple.
Some of these other passive crosovers have high-pass as high at 4000Hz, 5000Hz, or 6000Hz. Some have a much lower high-pass at 500Hz. 700Hz, or 800Hz. What would you even use those for?
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If you have a 6 ohm driver, is it better to use a 8 ohm or 4 ohm passive crossover in a pinch?
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The crossovers they are selling with a high pass between 500-800 hz, indicating a two way, are possibly intended for something like a horn speaker where there's a 12"-15" woofer and a compression driver mounted on a horn. Many feel keeping the crossover point out of the critical midrange frequencies (say 800hz-4khz) is a desirable thing.
If the 500-800hz crossover point is a low pass, then it's a 3 way crossover and will have a high pass crossover point likely in the 3kz-5khz range. As above, this keeps the critical midrange on 1 driver and keeps both crossover points out of that critical range.
If it's a 2 way crossover with a high pass at 4khz-5khz (unusual) it's likely meant to be used with a 'full range' driver that will cover the bass and midrange frequencies and then hand off to a tweeter, again, keeping the crossover point out of the critical midrange.
Since you can't take measurements, why don't you reach out to Parts Express with the names/models/impedance of your drivers along with the box volume (internal dimensions) and let them recommend the crossover they think will best fit your needs. They probably have a driver database and can make a better educated guess.
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If you have a 6 ohm driver, is it better to use a 8 ohm or 4 ohm passive crossover in a pinch?
Xovers dont have impedance per se.
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Don't forget baffle step!
Lot's of considerations...
I think this is ok to share here, right?
Danny Richie talking about the process high level... great foundation for questions like these, imo:
https://www.youtube.com/watch?v=lS-hbRziWtE