Crossover / Bandpass for LS50 "Bass Stands" and HT/SYN

[john61ct]

To try to keep my "Budget tall mid-bass to sub speaker, to act as stand for LS50s" thread

C

Post in thread 'Budget tall mid-bass to sub speaker, to act as stand for LS50s'

Sep 7, 2025

The HF version makes tradeoffs that will give lower distortion, but IIRC requires a larger cabinet. Both are good drivers which will be a step up from the TB 6.5" mini-sub.

"Boomy" bass is a function of speaker + room combined: if the room has a big 50Hz peak, anything that reaches down to 50Hz will sound boomy. People often blame bass-reflex designs for "boomy" bass, but that's because they tend to be designed to be approximately flat into the LF, which means any room modes are strongly activated. A sealed box might sound "tight" because it's -12dB@50Hz, so that peak might get the LF...

• ChrisG

limited to OTS products like Rythmik FM8, or on the DIY side, driver selection and enclosure issues.

As pointed out there, my Outlaw ICBM will let me set a "high" crossover of 120Hz between the LS50s and these stereo bass stands, which is OK I guess so long as placement happens to work out wrt room modes.

If not, I will really want to bandpass the bass stands and use mono sub(s) for the lower ranges that can be placed to suit, making the bass stands pretty much "mid bass" only.

The SYN 80Hz fixed LFE is fine for the mono sub(s) but Outlaw ICBM can only do "one side" of the bass stands.

I also wanted to maybe experiment with HPFing the LS50s a bit higher than 120Hz so using the Outlaw ICBM for the bottom side of the stereo bass stands might be better?

Can you suggest reasonably priced (not miniDSP) methods for accomplishing bandpassing or a more flexible "top side" crossover?

Ideally passive or at least DC powered?

analog filters?

car audio something like SOUNDSTREAM PROX4.1 ?

Rolls SX21 / SX45 ?

i won't let such solutions touch the LS50s unless advised SQ is not compromised, leave the Outlaw ICBM for all the "full-range" SYN channels.

Sorry for the brain dump

 

[Sokel]

Here to spoil the party, but...

Adding a real third way has nothing to do with adding a sub or two.
The addition must be treated as mains+bass module, a whole brand new speaker.
The reason probably that the market is not flooded.

For that alone you will need 4 independent channels, a flexible way to integrate them and of course a gazillion of (anechoic or gated,outside) measurements and spins.
If you're not ready to do the above it might be better to just add some subs and call it a day, plenty of "guides" around it.

If you stay under 120Hz it may be ok but then it misses the whole point of relieving the limited SPL Kef's and their distortion up to 200-300Hz or so.

Want impact? I would forget this, save as much as I can, sell the Kef's and go to a 3-way with enough size and juice.

 

[john61ct]

Thanks for that POV but...

Nope, the KEFs are the north star of my whole system, for portability.

Most of the rest will stay with the kids in the S&B once I go nomad in the next year or two.

Meantime I'm enjoying cobbling this HT / bass management project together on the cheap, in future hopefully getting into room correction etc.

Incremental improvements over time.

The learning process journey being fun! and more important than any destination, and above all realizing I won't ever get perfection.

 

[Sokel]

Thanks for that POV but...

Nope, the KEFs are the north star of my whole system, for portability.

Most of the rest will stay with the kids in the S&B once I go nomad in the next year or two.

Meantime I'm enjoying cobbling this HT / bass management project together on the cheap, in future hopefully getting into room correction etc.

Incremental improvements over time.

The learning process journey being fun! and more important than any destination, and above all realizing I won't ever get perfection.

It's the limitation you put that worry me.
The ironic thing is that you could go simple and cheap for an x-over there but AFTER you have spend much more to determine where and how.

You could do it with a cheap 2 channel in-4 channel out solution and PC software until you settle but that would mean that Kef's should stay in the equation at the whole process and as you value them enough you should know that it wouldn't be safe.

So...

 

[Ricardojoa]

It looks like the oulaw bass management doest have the distance/delay adjustment , ic that is try how are you integrating the sub or bass unit properly?

 

[john61ct]

Also Wiim Ultra models. In fact I have not seen any reasonably priced bass management that fit my needs, that include timing features.

I welcome any suggestions.

 

[john61ct]

It's the limitation you put that worry me.

Sorry which one specifically?

> You could do it with a cheap 2 channel in-4 channel out solution

Define cheap, any specific units that you reco?

I will parse that thread, thanks much for linking.

> but AFTER you have spend much more to determine where and how

?? I'm trying to gather the info required to prevent doing too much of that, getting lots of help from those members willing to help - gratitude to you and others!

> PC software

I don't have any working computers currently, can borrow temporarily if needed, but hoping to avoid dedicating such to audio service. For streaming my FLAC collection would likely spin up a VPS rather than self-hosting my own server(s)

but in future happy to consider anything that makes sense financially.

> Kef's should stay in the equation at the whole process and as you value them enough you should know that it wouldn't be safe.

Wut? I haven't come across any concepts that seem actually dangerous? Do you mean, like blowing out their cones or actually burning down the house? :-O

 

[kemmler3D]

If you are up for a challenge rather than just spending the money on MiniDSP or something, you can cobble together a few units like this: https://alitools.io/en/showcase/ada...-end-to-balance-very-low-noise-10000090227951

But

I don't have any working computers currently, can borrow temporarily if needed,

Will be a challenge when it comes to programming any DSP at all.

I was using a small mini-PC for EQ duties for a while, they can be had for (apparently) $60 on eBay and are totally adequate (in terms of CPU) for this kind of work. https://www.ebay.com/itm/187503326100?_skw=lenovo+mini+pc

The expensive part would be the multi output audio interface, but again looking for one used you might be able to get it done without going crazy.

Then you can run the whole crossover, EQ, etc with EQAPO. You can go as deep as you want with that, including with FIR, so your ability to integrate the speakers will be limited only by your patience and ability to measure output.

 

[Sokel]

Sorry which one specifically?

> You could do it with a cheap 2 channel in-4 channel out solution

Define cheap, any specific units that you reco?

I will parse that thread, thanks much for linking.

> but AFTER you have spend much more to determine where and how

?? I'm trying to gather the info required to prevent doing too much of that, getting lots of help from those members willing to help - gratitude to you and others!

> PC software

I don't have any working computers currently, can borrow temporarily if needed, but hooing to avoid dedicating such to audio service. For streaming my FLAC collection would likely spin up a VPS rather than self-hosting my own server(s)

but in future happy to consider anything that makes sense financially.

> Kef's should stay in the equation at the whole process and as you value them enough you should know that it wouldn't be safe.

Wut? I haven't come across any concepts that seem actually dangerous? Do you mean, like blowing out their cones or actually burning down the house? :-O

First of all you will need a PC and a measuring microphone for integration, there's no way around that, plus some time to learn how to measure (that's the learning part and it's fun! )

If you go the PC+software route you can get away with gear as @kemmler3D linked to you and with some caution you will avoid accidents (no, you won't burn the house but can promise about the Kef's, anyone messing with things like the ones you want to try knows what I'm talking about.

In general, you can't go "by ear" to something like this.
IMO, a measuring mic and the way to use it is the best thing you can do about your audio, in general.

So better find some cheap, sacrificial speakers for practice.

 

[john61ct]

OK, but DSPs for sure will need to wait. Before that I'll eventually set up REW etc

Is that specifically what is dangerous, the measurement process?

For now, spending $20 here $40 there on passive and/or even just analog tech is where I want to start. And yes, just playing it by ear.

Feedback on the examples I listed above would be much appreciated, as in, Does it do what it claim? Is it pretty clean, not interfere with the signal much?

That is BTW one of my issues with DSP also in general, especially for the main front pair when just listening to music.

Harrison Labs FMOD inline filters seem to have a good rep, do they have direct competitors?

 

[john61ct]

If you are up for a challenge rather than just spending the money on MiniDSP or something, you can cobble together a few units like this: https://alitools.io/en/showcase/ada...-end-to-balance-very-low-noise-10000090227951

Thanks but that does not look like a frequency filter?

I'm only looking for crossover related gizmo's - HPF, LPF and bandpass. Any others in that category? Ideally stereo, but of course can treat each side separately if needed...

Not just randomly trusting Ali sources, looking for specific recommendations from members here, ideally links.

BTW can a decent bandpass be created by just putting an HPF and LPF together somehow? Just wire in series?

 

[kemmler3D]

Is that specifically what is dangerous, the measurement process?

No, the danger is mostly from possibly making a mistake in the DSP settings and blasting a speaker with full output from the wrong frequency range and breaking it. Sometimes the volume control might reset without you noticing, etc.

The thing I linked to is based on a very well known chip and Wondom units are said to have very good analog performance for the money.

Active crossover boxes like the ones you've linked to should more or less work, but IMO there's a pretty low ceiling on the quality of integration compared with doing it digitally and with measurements.

The thing about DSP boxes or a PC is you can get dozens of filters going for the price of one of those analog boxes, with less noise and distortion and vastly more control. Band pass, but also every other kind of filter you can think of.

And fwiw yes you can effectively make a bandpass by combining HP and LP.

 

[Flaesh]

and bandpass

For what? You need HPF for KEFs and LPF for "bassstands"; and some PEQs may be usefull, especially for arbitrary homemade design.
p.s.: I think I'll put a winking smiley. Here it is

 

[john61ct]

The stereo basstands need both sides if mono sub(s) comes into the picture.

 

[john61ct]

Well quite the rabbit hole!

WRT damage issues (if I do get into DSP) why not put signal limiters in place as a precaution? They are easily bypassed when not needed, but even while in operation, are not supposed to affect SQ so long as gain remains below the threshold?

Seems like a good idea even "in production" when I'm not supervising, given my teenagers are constantly having friends over hanging out.

 

[john61ct]

I need to pay for at least one Wiim Ultra anyway, now thinking about using the Amp version as an external Power Amp for each pair, both LS50s and the basstands. Crossover functionality built in, also per speaker-pair EQ correction.

J

Post in thread 'Wiim announce WiiM Amp Ultra'

Sep 8, 2025

> when using it as a power amp for outside source signals

The included EQ feature could handle crossover filtering separate for each speaker pair, right?

How to connect the multiple Wiim's in the same room / system? Analog patches or

digital Linkplay over Ethernet, Group Lead handles the source, rest are Followers.

• john61ct

 

[john61ct]

For room correction and per-speaker correction MEASUREMENT, can REW on a PC do everything Dirac can?

Other than automating the actual EQ to be applied...

Dirac is just user-friendlier?

To be clear, not talking about having the PC tied into playing audio full-time, just for occasional cycles of measurement, ongoing EQ / correction itself handled by other devices...

 

[Flaesh]

sub(s)

Sorry, I missed it.
But the "bass stands" themselves for use with or without subwoofers are not the same thing..
For example, my subs work up to 80+ hertz, and the drivers in the waveguides from 666 hertz; therefore, my "bass stands" are designed for this range..

 

[JohnnyNG]

For room correction and per-speaker correction MEASUREMENT, can REW on a PC do everything Dirac can?

Other than automating the actual EQ to be applied...

Dirac is just user-friendlier?

To be clear, not talking about having the PC tied into playing audio full-time, just for occasional cycles of measurement, ongoing EQ / correction itself handled by other devices...

Here's a decent overview:

https://www.minidsp.com/applications/digital-room-correction/dirac-live-vs-rew

 

[john61ct]

the "bass stands" themselves for use with or without subwoofers are not the same thing..
For example, my subs work up to 80+ hertz, and the drivers in the waveguides from 666 hertz; therefore, my "bass stands" are designed for this range..

Well my current thinking is, that EQ crossover can start out letting the basstands go down as low as they go, if they only IMO partially substitute for subs, I get real subs later and then filter the basstands so they don't overlap too much.

Obviously they will be filtered to not step on the LS50s, in either case