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Speaker crossovers

plumberstrummer

plumberstrummer

Supporting Member
Jun 11, 2025
129
369
#1
Hello everyone! Ideally, I would like to get a couple of pretty robust speaker crossovers, dividing the speaker signal from the power amplifier above and below 200 Hz give or take. I can find this in car audio systems, but I’m not sure if this is potato potatoe. If anyone can point me to accompany (or away from a company) I’m all ears. Most importantly, I need to protect one set of speakers from the sub 200 Hz range. It can be an outboard unit, or something that I can build with soldering and all that. Any direction would help…
 
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#2
Beware of typical iron core inductors, when they saturate at low frequencies they can look like almost a short circuit (defeating their purpose). Air core is the preferred choice because they don't really saturate, but they are much bigger and require a lot more copper.

You will find that iron core inductors are typically used in the cheapest products, it's POSSIBLE to design around them but they tend to grow in size, weight and cost when you do it correctly.
 
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#3
agedhorse said:
Beware of typical iron core inductors, when they saturate at low frequencies they can look like almost a short circuit (defeating their purpose). Air core is the preferred choice because they don't really saturate, but they are much bigger and require a lot more copper.

You will find that iron core inductors are typically used in the cheapest products, it's POSSIBLE to design around them but they tend to grow in size, weight and cost when you do it correctly.
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thank you, man, as always :)
(now, I have to find some air core inductors!)
 
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#5
Redbrangus said:
It sounds like what you really want is a simple high-pass filter rather than an actual crossover. This is doable without inductors at all.
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Only if you are willing to accept mediocre first order results, and even then the series cap needs to handle a lot of ripple current with a high dissipation factor... this is harder than it appears IME.
 
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#6
plumberstrummer said:
Hello everyone! Ideally, I would like to get a couple of pretty robust speaker crossovers, dividing the speaker signal from the power amplifier above and below 200 Hz give or take. I can find this in car audio systems, but I’m not sure if this is potato potatoe. If anyone can point me to accompany (or away from a company) I’m all ears. Most importantly, I need to protect one set of speakers from the sub 200 Hz range. It can be an outboard unit, or something that I can build with soldering and all that. Any direction would help…
Click to expand...

How about a used dbx crossover? What's the project you have brewing?

Riis
 
#7
agedhorse said:
...this is harder than it appears IME.
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I agree that doing this with passive components is difficult. I'm suggesting that it's a task better and more easily accomplished at the signal level.

For the OP -- is this a bass cab with both bass and guitar speakers in it? Or is it a cab you'll be playing both guitar and bass through?
 
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#8
Redbrangus said:
I agree that doing this with passive components is difficult. I'm suggesting that it's a task better and more easily accomplished at the signal level.

For the OP -- is this a bass cab with both bass and guitar speakers in it? Or is it a cab you'll be playing both guitar and bass through?
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This is a speaker cabinet for a unique bass amp that I have which does a particular sound that is very distorted. I have been running into some issues with most of the cabinets I own, and have played sounding way too harsh or way too dark.

I found a guitar speaker which has just the right balance, but can’t handle sub 125hz frequencies. After a lot of research, and very generous A+ wisdom from a lot of you guys on here (especially @agedhorse; I cannot say enough words of gratitude to him) it has become glaringly clear that Bass frequencies are profoundly complicated and I am in way over my head with this.

That said, I now have a fully engineered 412 cab design for the Bass speakers at least! I do still hope to try and use the guitar speakers I want with these speakers, but it does appear that I may end up scrapping the Guitar speaker aspect. At this point, that may be OK. Either way, I have a plan A and Plan B.

Plan A is to (essentially) have a 212 Guitar cabinet protected by crossover to only see above 200 Hz, and a 212 Bass cabinet to cover the under 200hz.

Plan B is: as long as the bass speaker Cab, I’ve had Engineered sounds good enough, I will cut the top end and dial in the sound I want with it however it is.

Ultimately, I already have a bi-amp rig which works and was the inspiration for this amp and cabinet design in the first place. Now that I know what I’m doing, I can dial that in better in front of the two amplifiers, using the right cabinets. I’d hoped I could get closer with one head and one cabinet, but I can’t argue with physics. I’m happy to submit to God’s law, however the chips may fall on this.
 
#10
I like the suggestion of dividing up the signal prior to the power amplification stage for a few reasons. There are off the shelf devices like the Rolls that OnlyFlats mentioned above, and other similar devices from Ashly, Berhinger, Dbx, and other companies that provide the capability to make adjustments to suit different circumstances.

Filter networks designed to be placed between the power amp and speaker are usually fixed as far as frequency and slope are concerned and you must have a good idea of what your intended response needs to be while taking into account the characteristics of the high frequency driver component of the speaker system. A variable filter network after the power amp that allows the user to tune the response on the fly is possible but the cost is greater than that of a fixed filter network.

We used to use Altec outboard fixed crossover filter networks feeding separate power amplifiers powering Gauss horns enclosed in separate boxes that sat on top of the huge EV mains back in the days when dinosaurs roamed the earth. Later we upgraded to Dbx programmable crossovers, and still have them in some unused amp racks. They worked great at the time but I don't miss them one bit. We are after all living in the twenty-first century.

You mention building your own. I don't recommend it but If I was going to do so I might start by reading what Howard M. Tremanie wrote about the subject in various books: Howard M. Tremaine | Open Library

These days if you are willing to spend the money you can buy smaller lighter louder much better sounding and more tunable equipment rather than messing around with fixed passive speaker level filter networks and bi-amplification.
 
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#11
Definitely best to do it active before the amps, if you intend to keep it bi-amped.

Passively, I don't think will be your friend unless you really know what your doing. There's a lot more to it than just inductors and capacitors.
 
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#12
If you Google ‘band-pass passive cross over’ you’ll see plenty of products available as naked or enclosed.

Assuming you’re not fussy about slopes and willing to try a few things you’ll find things like:
(180Hz is close-ish)
Might be junk, might be just the ticket. I’d not believe the stated power handling (nor any of the other specs tbh!!)

1772805113574.png
 
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#14
JamesGrant said:
If you Google ‘band-pass passive cross over’ you’ll see plenty of products available as naked or enclosed.

Assuming you’re not fussy about slopes and willing to try a few things you’ll find things like:
(180Hz is close-ish)
Might be junk, might be just the ticket. I’d not believe the stated power handling (nor any of the other specs tbh!!)

View attachment 7446911
Click to expand...
Thank you! This is basically what i was looking for, but is not available in USA anyway… :rolleyes: Murphy law is the law of the land over here.

In any case, I am going to take @agedhorse lead and build a box just like this with Air Core Inductors. Hopefully it’ll sound good, but like i said I’m prepared for it either way.
 
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#15
6thplanet said:
Definitely best to do it active before the amps, if you intend to keep it bi-amped.

Passively, I don't think will be your friend unless you really know what you’re doing. There's a lot more to it than just inductors and capacitors.
Click to expand...
Thank you - I know what i can do for the bi-amp version of this rig, the issue is the single amp one. For the signal coming out of one head, i just want to protect my guitar speaker cab from the lowest frequencies. Hopefully, i can do so well enough with air core inductors, capacitors, some high quality wire, solder and jacks.
 
#17
6thplanet said:
Just be aware speakers are not resistors, and 8ohm speaker isn't 8 ohm throughout its frequency response. We're hinting to there's more to it than just picking an inductor and capacitor from an online calculator. Good luck on your project.
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Thank you for the warning. I’m happy to take some direction on this, if you can point me to some reading material.

Here is the diagram that was drawn up for me by the supplier i’m working with. Hopefully this is correct, as i’m trusting they know what they are doing… if it is completely off, i’m happy to adjust. My one plan is to get the parts they suggested, use the air core inductors, and high quality parts. I do plan on building well past my watt needs. In this diagram, he has it wired directly to the speakers, but I’ll be making an outboard box.
IMG_8388.jpeg
 
#18
plumberstrummer said:
Thank you for the warning. I’m happy to take some direction on this, if you can point me to some reading material.

Here is the diagram that was drawn up for me by the supplier i’m working with. Hopefully this is correct, as i’m trusting they know what they are doing… if it is completely off, i’m happy to adjust. My one plan is to get the parts they suggested, use the air core inductors, and high quality parts. I do plan on building well past my watt needs. In this diagram, he has it wired directly to the speakers, but I’ll be making an outboard box.View attachment 7447059
Click to expand...
If the top woofer fails short circuit, your amp will likely fail as well because of the resulting capacitive load.

A 2 layer voice coil (like what’s used in most guitar speakers) can fail short circuit fairly easily when thermal limits are reached.

I think you will discover that the cost and size of appropriately rated parts will be “staggeringly” high.

You man not want to low pass the bass speakers either, or your results will be worse than a middle of the road combo.
 
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#19
agedhorse said:
If the top woofer fails short circuit, your amp will likely fail as well because of the resulting capacitive load.

A 2 layer voice coil (like what’s used in most guitar speakers) can fail short circuit fairly easily when thermal limits are reached.

I think you will discover that the cost and size of appropriately rated parts will be “staggeringly” high.

You man not want to low pass the bass speakers either, or your results will be worse than a middle of the road combo.
Click to expand...
thank you. So, if I go for the air core inductor I should avoid the likelihood of a short circuit due to thermal limit issues? happy to not do the low pass thing either…

I am prepared to get the appropriately rated parts, this is just a one off thing anyway… Any companies you like to work with and trust for something like this?
 

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