Adding woofers to 2-way cabs

[loafeye]

I have a spare pair of (passive) 2-way speakers. I'd like to add the use of the woofers in the spare set to the passive 2-way speakers I have in service now.
I don't want to break into the sealed enclosures of either set to re-wire them with new 3-way crossovers (bad idea as drivers not optimized for such- I'm known to myself as a not-a-speaker designer).
If I had a pair of passive sub-woofer crossover filters, I could run the speaker-out cables from my amp to the sub crossover and through it, so I'd be using the woofers in one speaker pair and the other speaker pair would get all the frequencies above the sub crossover frequency, whether it's 80,100,120,200 Hz, whatever.

This is just a lark, where the spare 2-way speakers are currently useless, and I might realize improved sound by carving up the frequencies between the two woofers, in a sense, making one of them a "mid-woofer" and using the tweeter in the same cabinet. If I don't like the result, I can just disconnect the spare pair and continue to use the speakers as I have now, which would be fine.

The trick is, I can't find a passive sub-woofer crossover, and I'm incapable of designing one. If I at least had a schematic and the parts were available, I could probably solder the chokes, resistors, and caps together to get the job done, but a known-to-work-already-built crossover would probably be the smarter move on my part.
My thanks for any suggestions.

 

[gab]

Not knowing anything about your current passive 2 way speaker setup, you might want to study Jeff Bagby's (RIP) woofer add-on designs available from Meniscus Audio:

Kairos Woofer Module Kit | Meniscus Audio

1 Pair Woofer Modules

meniscusaudio.com

PDF writeup at the bottom

 

[fpitas]

Passive subwoofer filters are like hen's teeth, because they're the size of a small car and expensive. DSP is generally used now, although there are a few line-level op-amp solutions available.

 

[loafeye]

PDF writeup at the bottom

This is excellent; thank you.

 

[loafeye]

Passive subwoofer filters are like hen's teeth, because they're the size of a small car and expensive. DSP is generally used now, although there are a few line-level op-amp solutions available.

Thank you for the lead-in/pointer. For the purpose I'm asking after above, to use a DSP it seems I'd need a second 2-channel amp for the passive speaker pair I want to add, and then be restricted to using a volume control upstream of the DSP.

 

[hchrist]

Hi there, I'm new to this forum so not sure if this is the right place to ask this question or request for help, but becuase I have Jeff Bagby's Kairo's and this forum talks about them, I thought it would be a good place to start.

I built a pair of JB's Kairo 2-way bookshelves and then I also bought the add on Bass woofer kit (all from Meniscus audio) back in 2020. I have been running these speakers from an Emotiva XPA-200 2-channel power amp and a Yamaha WXC-50 MusicCast Streaming Pre-Amplifier to stream my music in a 2nd music listening room.

I have recently bought 2 x Fosi audio class D, ZA3 amps, which I am wanting to run in mono mode to power the Kairo 2-way's with (the top bookshelf speakers). And then I want to use the Emotiva XPA-200 to power the 2 bass cabinets (which are passive and are the 3-way part of the 3-way speaker set up) so that the subs have independant power.

So essentially 2 mono blocks running each Kairo 2-way bookshelf and then the 2 channel power amp to run the bottom bass cabinets. But I'm not sure how I'm supposed to connect this up. Currently, the 2 RCA outputs run from the Yamaha streamer DAC from the Aux out into each channel of the Emotiva XPA-200. How do now get the RCA signal from the emotiva (which I want to run the bass cabinets (bottom speakers of the 3-way Kairo set up)), and also into the Fosi Audio inputs to run the 2-way bookshelf top half of the speakers? Do I need a Y splitter to split the signal coming from the streamer, and if so, is this the only way and if it is the only way, do I reduce the quality of the signal by doing this?

Also, the way that Jeff Bagby designed his 2-way Kairos, with the add on bass cabinets, is that he has 2 terminals in the top bookshelf, 2 terminals in the top of the bass cabinets (so you can connect from the 2-way Kairo bookshelf to the bass cabinet), and then another set of terminals that run from the bottom of the bass cabinets into the power amp speaker terminals. Inside the bass cabinets, are the crossovers for when the Kairo top bookshelf 2-way speaker connects to the bass cabinet, it then knows to reduce certain lower frequencies from the above 2-way Kairo bookshelves. And it also reduces the higher frequencies in the bass cabinets below the 2-way Kairos that are sitting on top.

So theres another part to my question - If I am to run the speaker cables directly from the 2-way Kairos, into a power amp (or 2 fosi audio ZA3 mono's), and then, run the bass cabinets into the Emotiva XPS-200 2 channel power amp, even if I DID split the RCA signal, the 2-way Kairos, would be running the midrange drivers at full range, and not reducing the bass being sent to the mid driver, because they won't be connected to the bass cabinets, which contain the high pass filter/crossover that determines the frequencies to send to each speaker.

Oh also, I'm looking at upgrading my Yamaha streamer to one with XLR outputs, as both my Emotiva XPA-200 and the Fosi Audio ZA3's have XLR ins.

I hope all of this make sense. Please help? Any suggestions?
Any questions, please fire away.

 

[RickS]

While we could parse terms, Jeff's bass module is really just a passive subwoofer with a high pass filter to connect the Kairos.

Here is a my quick take on what I would do in your situation. Split the WXC-50's subwoofer out and connect to the Emotiva amp for each bass module. Move the high pass circuit out of the bass module and connect it to the back of the Kairos as Jeff shows below...

Connect the pre-outs to the Fosi's and connect to each high pass filter to power the Kairos. Unless you have a measurement mic or SPL meter, set the voule on the Fosi's to get a good match with the bass module level and you are done.

This might sound somewhat better than the previous stereo setup. To really improve, would need to replace the passive crossover with a minidsp or other active crossover.

 

[hchrist]

While we could parse terms, Jeff's bass module is really just a passive subwoofer with a high pass filter to connect the Kairos.

Here is a my quick take on what I would do in your situation. Split the WXC-50's subwoofer out and connect to the Emotiva amp for each bass module. Move the high pass circuit out of the bass module and connect it to the back of the Kairos as Jeff shows below...

View attachment 380035
Connect the pre-outs to the Fosi's and connect to each high pass filter to power the Kairos. Unless you have a measurement mic or SPL meter, set the voule on the Fosi's to get a good match with the bass module level and you are done.

This might sound somewhat better than the previous stereo setup. To really improve, would need to replace the passive crossover with a minidsp or other active crossover.

Hi Rick, Thank you so much for your advice. Much appreciated.

Yes I had a sneaky suspicion I might have to move the high pass filter from the bass cabinets, out, in order to reduce the lower frequencies from the mid driver in the 2-way Kairos - Very annoying and not really something I want to do. But you mention the other option is to 'replace the passive crossover with a minidsp or other active crossover".
That would mean I don't have to remove the high pass filter in the bass cabinets, correct? And I could still connect the terminals from the 2-way Kairos, to a minidsp or active crossover and do the same as you have suggested, as well as connect the bass cabinets as they are into the Emotiva and the crossover in those cabinets would still remove the high frequencies from the bass cabinets. right? If all of that is correct, do you have any suggestions an active crossiver I could use? Thanks again.

 

[RickS]

If you went with an active crossover, the existing passive parts would need to be bypassed or removed entirely.

 

[hchrist]

If you went wih an active crossover, the existing passive parts would need to be bypassed or removed entirely.

Ah ok fair enough. Thanks again for your reply. Much appreciated.

But if I went with a minidsp, I wouldn’t need to remove the passive crossovers?

 

[RickS]

Ah ok fair enough. Thanks again for your reply. Much appreciated.

But if I went with a minidsp, I wouldn’t need to remove the passive crossovers?

I would remove them but you could you could just disconnect them and wire the woofer directly to the binding posts.

 

[hchrist]

I would remove them but you could you could just disconnect them and wire the woofer directly to the binding posts.

Thanks again for your input and advice. Much appreciated.

 

[Ktacos]

I pursued this very thing and even parsed the bagby article that sent to me by a few people. Ultimately this isn't even something I'd attempt to approach passively, it's really a job for active filtering. I ultimately disliked the end result for a few reasons and now the bass modules are just subs and the speakers are on stands. Granted I was running my woofer up to 350-400 and things can get tricky there in terms of room excitement.

 

[hchrist]

I pursued this very thing and even parsed the bagby article that sent to me by a few people. Ultimately this isn't even something I'd attempt to approach passively, it's really a job for active filtering. I ultimately disliked the end result for a few reasons and now the bass modules are just subs and the speakers are on stands. Granted I was running my woofer up to 350-400 and things can get tricky there in terms of room excitement.

Thanks for your feedback and response. So did you convert the bass modules to active by adding amps to them? Can you send me some more info on what you did and how you have them connected, running them with what, any changes u made/parts removed etc please? Thank you

 

[Ktacos]

They got their own amp (crown xli800) and I do my dsp in the computer via the onboard 5.1 spoofed into 6 channels for 3 channels per side. Plenty of other options for hardware dsp out there both low cost all the way up to the price of a car.

 

[hchrist]

They got their own amp (crown xli800) and I do my dsp in the computer via the onboard 5.1 spoofed into 6 channels for 3 channels per side. Plenty of other options for hardware dsp out there both low cost all the way up to the price of a car.

So you removed all the passive crossovers inside the bass module/cabinets? Or left them inside and connected to the internal terminals? And now you run a dsp to control what frequencies to send to the woofers?

 

[Ktacos]

So you removed all the passive crossovers inside the bass module/cabinets? Or left them inside and connected to the internal terminals? And now you run a dsp to control what frequencies to send to the woofers?

No passive components in any of my speakers, everything is filtered actively, but ultimately you'd just totally remove the passive components and wire straight to the amp.

 

[hchrist]

No passive components in any of my speakers, everything is filtered actively, but ultimately you'd just totally remove the passive components and wire straight to the amp.

Sorry but I’m still confused/lost. All this passive/active/dsp talk is a bit over my head.

Are you saying your speakers have no crossovers in them at all and a crown xli800 amp powers and runs them, but then some software on your computer talks to the crown amp and tells it what frequencies to play out of the woofers? Does the software connect to the crown amp and upload the information?

And I’m also a little confused because all 2-way, 3-way factory bought non powered (passive) speakers come with crossovers inside them - so if someone buys a dsp (which my understanding is a piece of equipment/software that can control what frequencies to send to what speakers), I can’t see how people would be removing the crossovers from these factory speakers?

Sorry if I’m not understanding correctly. Just trying to understand how all this dsp active stuff works.
Thanks again for your input/advice and help. Much appreciated.

 

[DVDdoug]

In case you don't know this, the standard-everyday solution is an AVR which has a built-in crossover ("bass management"), connections for passive main speakers, and a low-level output for an active sub or a separate sub amplifier. My DIY subs are passive and I'm using an "extra" amplifier that I already had.

Parts Express sells passive (and active) crossovers, high-low-pass crossover "modules", components, and boards if you want to solder-on your own components.]
Or there are "pro" active crossovers, or the miniDSP is popular.

DSP means digital signal processing. Audio effects used in audio production (compression, reverb, EQ, etc.) are usually DSP. Active crossovers can be digital or analog. The advantage of digital is that it's highly and easily configurable and adding a dip, bump, or notch, etc., is simply a matter of re-programming. And making a steep filter is just a matter of software and processing power. With analog it gets complex. You don't usually NEED that with a crossover so often analog is fine.

I can’t see how people would be removing the crossovers from these factory speakers?

Probably most people doing that build their own speakers. Some speakers have separate high-low frequency connections for bi-amplifying, but you can't bypass the internal crossover.

I've seen pro setups for live sound or DJ use with separate horns & subwoofers. The midrange MIGHT be handled by a full-range speaker with an internal passive crossover for
its internal drivers.

I have a tri-amped system in my van. Originally, I had an active crossover and 3 stereo amplifiers. But I occasionally had trouble with it so how I have a 5-channel amp with built-in crossovers.

 

[hchrist]

In case you don't know this, the standard-everyday solution is an AVR which has a built-in crossover ("bass management"), connections for passive main speakers, and a low-level output for an active sub or a separate sub amplifier. My DIY subs are passive and I'm using an "extra" amplifier that I already had.

Parts Express sells passive (and active) crossovers, high-low-pass crossover "modules", components, and boards if you want to solder-on your own components.]
Or there are "pro" active crossovers, or the miniDSP is popular.

DSP means digital signal processing. Audio effects used in audio production (compression, reverb, EQ, etc.) are usually DSP. Active crossovers can be digital or analog. The advantage of digital is that it's highly and easily configurable and adding a dip, bump, or notch, etc., is simply a matter of re-programming. And making a steep filter is just a matter of software and processing power. With analog it gets complex. You don't usually NEED that with a crossover so often analog is fine.


Probably most people doing that build their own speakers. Some speakers have separate high-low frequency connections for bi-amplifying, but you can't bypass the internal crossover.

I've seen pro setups for live sound or DJ use with separate horns & subwoofers. The midrange MIGHT be handled by a full-range speaker with an internal passive crossover for
its internal drivers.

I have a tri-amped system in my van. Originally, I had an active crossover and 3 stereo amplifiers. But I occasionally had trouble with it so how I have a 5-channel amp with built-in crossovers.

Thanks again for your detailed explanations and help. Much appreciated.

Ok so my Jeff Bagby Kairos 2-way bookshelves with add on bass cabinets (that turn them into 3-ways), already have all the passive crossover components wired inside the cabinets.

I don’t want to mess with that current set up.

Obviously Jeff has designed his Kairo crossovers to be perfect for the SB acoustic drivers he has selected, and when adding the sub cabinets he’s also created crossovers to reduce midrange drivers bass and crossovers go the sub modules to handle only bass frequencies.

I’m also not use an AVR or not using a big pre amp with all those capabilities.
I’m strictly using this is a stereo set up for music listening.

I have a 2 channel power amp with a dac/streamer being used as the pre-amp.

I’m thinking, all I really need is possibly a dsp or another external passive crossover to connect to the 2-ways, so I can just reduce the bass that is being sent into the 2-way Kairo’s midrange driver. Because the crossover inside the bass module will handle lower frequencies and the. Crossover in the 2-ways handles what is being sent to the tweeters. Right?

Then I can use the Fosi Audio ZA3 mono blocks to power the 2-way Kairos and the 2 channel Emotiva power amp to power the bass cabinets.

Isn’t it as simple as that? And as mentioned above, I just need to send via RCA’s from the sub out on the streamer into the Emotiva power amp to get the signal to those speakers?

If all that makes sense and is correct, I’ll have a look at the link (thank you) you provided for the crossovers at parts express. Thanks again.