High Pass Filter, better at speaker in or at line out?

Thinking of integrating a high pass filter into my system. Couple of questions for the brain trust.

  1. Theoretically which would be the more “pure” a line out filter from the preamp to the amp or a a filter at the speaker lead going into the speaker?

  2. Not to get crazy over a an active/passive discussion but the only reason I’m looking at passive is that I simply don’t know what my active options are. All I’m looking for is a way around my preamp not having a sub out high pass out circuitry built in.

  3. and I guess most importantly, how much am I leaving on the table by having a full signal being fed into my speakers? This would be for use with a pair of Philharmonic Audio BMR speakers. The increased power handling as a byproduct would be a nice secondary bonus.

This is the guide I’ve been looking at. I also have a high pass whitepaper that I can use to come up with the specific values I’ll need for my speakers.

Thoughts welcome.

at the speaker terminal. while i have not personally used one, everything i have read and seen, has said to mount it at the speaker terminals.

the biggest thing about not low passing your speakers, is low end energy. if you let them play low end, they will use a lot of the juice just for that. if you restrict them to 40/60/80/100 or whatever, they can use the energy for mids and highs better. in theory they will sound better and play louder(the sound better is debatable, but the volume is real)

edit: you can also pop a driver off and add it inside the speaker box. when using a physical low pass, and not digital, you are adding in another xover component.

edit2: you can also build it its own mini box to add behind your speakers. i personally just don’t like components out in the open. they get more moisture and potential damage easier.

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I hadn’t thought about just putting it right at the woofer. Would do the same job as if it was outside, I like that suggestion.

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that site has a lot of good info on it, and xover calculators.

on a side note, while your figuring out your low pass point, if you plan on trying a couple different points, mount them outside for ease until you find your final point.

edit: and buy cheap parts initially if you plan on testing a few points. cheap parts are really really cheap, but work for testing. then buy better parts for final build as quality xover parts can be pricey. and the phil harmonics are good speakers. don’t want to use cheap xover parts.

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what subwoofers do you use with them out of curiosity? a lot of mid to higher end subs have built in filters.

It’s a Rythmik L12. Love the sub but no high pass out. Yeah, I’ll do some testing with cheap caps first. The site is pretty good just wondering whether or no it’s worth the effort but given the relatively cheap cost if I go inside the speaker right as the woofer. It’s worth it to try it out.

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yeah testing is only a few $ for cheap parts.

edit: lol shipping will most likely be more then the part cost for testing purposes

im jealous lol. thats my next major audio purchase. pair of rythmik drivers. i want to build my own enclosures. they will look like end tables :slightly_smiling_face: i own 1 sub i don’t use atm because the wife hates looking at it. so its in its box stored away lol.

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HA! Thankfully my wife has a high audio equipment approval rating. I’m lucky. :wink:

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It’s all about implementation. You can make (or buy) a simple RCA level filter like this: Line Level Crossovers or put it at the speaker. If you put it at the speaker, it will always be there regardless of the electronics you put in front of it. Also there are way more parts available for speaker crossovers so you can choose level of component parts much easier. Another benefit of putting it at the speaker is that you can add a sub without having cut the bass from the low level signal before hand.


My alternative would be something like this. I’d have to put it between the pre out and then feed to the sub and the speaker amp.


Mini DSP also makes a pro version that would go between my streamer and DAC with the sub out directly from this. SHD Studio - All Digital Processor

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This might be the simplest (and cheapest) place to start. Basically to see if I like the sound. Easy to put between the preamp and amp.

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Researching, ran across this from dbx

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Never been a fan of the cheap pro audio stuff. If you want a quality crossover without braking the bank, look at the Audio Control mobile stuff. They no longer make them but there are plenty used very cheap. But, you will need a 12V power supply.

After much reading… Figure I might as well ask. Seems that the cleanest solution for me will be a high pass at the woofer will install inside the speaker. So if you’d be so kind… I can put a 800 μf capacitor inline, the woofer is 4 ohm and that will give me a simple high pass at 50Hz.


Reading that a more effective high pass will be a 2nd order high pass that will give a steeper 12 dB per octave slope. But I’ve not been able to take the results of the online calculators and turn that into the parts I’d need to order.

Would you be so kind?

4 Ohm Woofer

What capacitor value on the + into the woofer.
What resistor value bridging the + and - the woofer.

It’s a bit more complicated than that. For a proper filter you need to know the frequency response of the driver in the cabinet. But, to keep things simple, you can use this:

Put whatever in the woofer box, 4 ohms in the tweeter box, 50Hz or whatever in the frequency box and choose “2nd order Linkwitz-Reily” filter in the dropdown. From the results just use whatever is given for the tweeter part of the crossover. You’re using tweeter values because you want the high pass part of the network.

DBX makes solid equipment.
Main issue with their gear is the learning curve as the manuals are not great. So just trial & error to success.

Since DSP and Speaker Management Systems are so common in PA now, the “ol’ chonky” crossovers no longer exist. So unless you want to hunt old gear and overhaul it completely, the DBX stuff is the best you get.

General word about PA-gear at home:
While all the hardware knobs and lack of flimsy nonsense may be very appealing, I am guilty of giving PA-gear those looks myself, you need to know remember the vastly different uses cases for Hi-Fi and PA equipment!

Crown XLS amps that bad ? Because theyre cheap and have crossovers.

Eww, yes. :wink: