Looking for help with passive sub low pass filter

[SmellyOldMan]

Hi everyone, first post here.

I've been lurking here for a while now and I'm in need of help.
I am looking for a simple low pass filter for my Braun LW1 passive subwoofer.

At the moment its simply connected to the amp with 2 pairs of speaker cable, along with a set of regular speakers.
Channel A is for the regular speakers, channel B for the sub, meaning the sub receives a full range input.
The sub clearly produces higher tones than just bass which muddies the sound of the regular speakers.
My amp is old like the subwoofer, so no dedicated sub out.

I'd like to have a simple filter that I can just connect to speaker cable inputs on one end and speaker cable outputs on the other end.
Something that looks like those ground loop isolaters, or like an optical to analog converter box, just a simple box with inputs and outputs.
However, this turned out to be more difficult to find that initially anticipated.
All I can find are weird, bare little boards or inline RCA plugs.

Does a complete low pass filter exist as a finished product? One with a nice little enclosure that takes regular speaker wire?

Or, if this doesn't exist, could anyone recommend any of the bare board filters?
And how would those RCA filters work in this scenario, purchase some speaker-cable-to-rca-adapter-plugs for both ends?

Thanks in advance for any help!

Edit - I think I'm looking for an adjustable external crossover.... controller? Amp? something external, plug n play, adjustable. I've found a couple of devices that look sort of what I think I need, but those are 200+ bucks which I find a little expensive for a complete gamble.

 

[OldGman]

I would imagine there would be an internal crossover of some sort in there....a simple board with an inductor and cap to cut off higher frequencies.
Where that is who knows? 150 hz-200hz ?
Many "vintage "passive subs had no crossover control and set too high ( frequency wise) for my taste.

Failed cap/caps perhaps effecting its performance?

 

[billyz]

In my experience a steep slope crossover is less muddy. Probably want 24db slope.
The steeper the slope the more complex and phase becomes an issue. A really good one is very speaker specific. You need to know quite a few of the parameters of the speakers involved. And these usually need to be measured first, if not published already. The components can be expensive when considering the Wattage and specific frequency, lower frequencies are much more expensive. And then it is just an experiment and may need to adjusted for the room , etc. In the end many opt for an Electronically adjustable outboard component. IE, more expensive.

 

[SmellyOldMan]

I would imagine there would be an internal crossover of some sort in there....a simple board with an inductor and cap to cut off higher frequencies.
Where that is who knows? 150 hz-200hz ?
Many "vintage "passive subs had no crossover control and set too high ( frequency wise) for my taste.

Failed cap/caps perhaps effecting its performance?

Well, it's doing the low frequencies, but also much higher ones. So I don't think its broken or in need of service, its just an old passive sub. It reaches nowhere near as high as the regular speakers so its at least filtering something already, but its just too much of the higher frequencies for my taste.

As its a passive sub it indeed doesn't have any external controls. Maybe internally but its literally also a saloon table and completely sealed, no way to disassemble it non-destructively.

 

[SmellyOldMan]

In my experience a steep slope crossover is less muddy. Probably want 24db slope.
The steeper the slope the more complex and phase becomes an issue. A really good one is very speaker specific. You need to know quite a few of the parameters of the speakers involved. And these usually need to be measured first, if not published already. The components can be expensive when considering the Wattage and specific frequency, lower frequencies are much more expensive. And then it is just an experiment and may need to adjusted for the room , etc. In the end many opt for an Electronically adjustable outboard component. IE, more expensive.

The sound quality isn't amazing anyway so I'm not looking for the absolute best quality solution. I'd just like to optimize it a little without spending too much, but it looks like I'm looking for a strange unicorn device in the audio world that for some reason just doesn't appear to exist.

 

[OldGman]

That's crazy how there would be no access to the internals via one of the woofer cutouts for servicing.
I looked up the Braun and found this. Extremely hard to read if even legible.
Obviously way above my pay grade to ask but could one (with test equipment) change out inductors/caps etc to lower the cut off without effecting the impedance and output too much ?
I know........probably too many variables and cost.
Yet I ask out of curiosity .

Sorry I'm no help to the OP.

 

[SmellyOldMan]

That's crazy how there would be no access to the internals via one of the woofer cutouts for servicing.
I looked up the Braun and found this. Extremely hard to read if even legible.
Obviously way above my pay grade to ask but could one (with test equipment) change out inductors/caps etc to lower the cut off without effecting the impedance and output too much ?
I know........probably too many variables and cost.
Yet I ask out of curiosity .

Sorry I'm no help to the OP.
View attachment 3508654View attachment 3508655

There might be a way to get in through the front, but there's a mesh thats sort of pressure fit in. I tried getting it out before to clean it but it was not cooperating.

I would like to avoid modding it anyway, hence my search for an external solution.

 

[kmagnuss]

They have many frequencies to choose from:

Parts Express 80 Hz Low Pass 4 Ohm Crossover

Parts Express 80 Hz Low Pass 4 Ohm CrossoverConvenient crossovers that work great in any application requiring economical and flexible filtering. Also for use in car stereo installations with component speaker systems. Low pass, band pass, and high pass models complement woofers, midranges, and...

www.parts-express.com

 

[Dr. Beaker]

Marchand makes a plug and play passive line level crossover that might work for your application. They also have speaker level crossovers (XM48).

XM46SB

XM48

 

[SmellyOldMan]

They have many frequencies to choose from:

Parts Express 80 Hz Low Pass 4 Ohm Crossover

Parts Express 80 Hz Low Pass 4 Ohm CrossoverConvenient crossovers that work great in any application requiring economical and flexible filtering. Also for use in car stereo installations with component speaker systems. Low pass, band pass, and high pass models complement woofers, midranges, and...

www.parts-express.com

Thanks, I also found many of these type of filters but these are all meant for internal use right? Like for people building their own speakers? I could DIY something with this but I am looking for a plug n play solution, ideally adjustable too.

 

[SmellyOldMan]

Marchand makes a plug and play passive line level crossover that might work for your application. They also have speaker level crossovers (XM48).

XM46SB

XM48

Thank you for the suggestion, are these normal prices for a device like this? I find 190 bucks, let alone 550, a little steep, especially since the sub itself was rather cheap.

 

[kmagnuss]

Thanks, I also found many of these type of filters but these are all meant for internal use right? Like for people building their own speakers? I could DIY something with this but I am looking for a plug n play solution, ideally adjustable too.

It's pretty darn easy to use... just crimp some spade terminals on your speaker wires and hang it off the back of the speaker. Shouldn't take 5 minutes.
Anything adjustable is going to be for a powered amp or really expensive.

 

[SmellyOldMan]

It's pretty darn easy to use... just crimp some spade terminals on your speaker wires and hang it off the back of the speaker. Shouldn't take 5 minutes.
Anything adjustable is going to be for a powered amp or really expensive.

Hmm maybe you're right. I have managed to get it open from the front in the mean time, looks pretty simple inside. There's literally nothing more than this, and its exactly the same on both sides. The rest of the box is empty apart from the isolation stuff and a divider in the middle.