2.5-way DSP crossover - help

2234rew

Member
Thread Starter
Joined
Nov 24, 2020
Messages
233
Hi @juicehifi Bernt

Can you help with setting up DSP crossover for this 2.5-way speakers.

It is only 2-channel full-range, and no subs - which simplifies things !

Wiring to only 3 drivers in total, as per photo below. There are 2 passive radiators

There is coaxial midrange (LMF) and tweeter (HF).

You can see what it looks like below but someone's description of how to setup the crossover (which i want to replicate in Audiolense) is:

The way this speaker works is that the LF has a 1st order low pass at around 300Hz (from memory) and at the same frequency you have a shelf filter on the LMF driver to raise it by ~6dB.
If you do this carefully you will end up with LMF and LF both working below 300Hz, LMF only working above 300Hz, and a flattish frequency response from the summation.
Then you need to do the crossover to the HF at around 2kHz. Apply the 2kHz low pass filter to both LMF and LF too. Can use a 2nd order but in active I'd recommend you go 4th order.
I'm confused how to do these shelf filter?
And how to apply both low pass and shelf to the midrange (LMF)?
And 2kHz low pass for both LMF (midrange) and LF (woofer)?

52230


52232
 
Last edited:

kevinzoe

Registered
Joined
Jun 10, 2022
Messages
3
My AV System  
Preamp, Processor or Receiver
PrimaLuna DiaLogue Premium preamp
Main Amp
PS Audio BHK Signature 250 stereo amp
Additional Amp
Valve Amplification Company 30/30 Renaissance
Computer Audio
JRiver
DAC
exaSound e48 (8 channels)
Front Speakers
Acoustic Zen Crescendos
Subwoofers
Pair of Rythmik F15's
Other Equipment
Cables by: TEO Audio, Cardas and AudioSensibility
The way someone has told you how to construct the XO shows that the LF has 2 low-pass filters applied to it - one at 300Hz and another at 2Khz. This seems odd to me . . . If it were me, I'd ignore the low-pass filter at 2KHz for the LF bass driver as it's already been taken care of by the 300Hz one. If a second low-pass filter is needed by the LF driver then try reducing the width of the XO instead.

Regarding the shelf filter, I would think that the correction filter will boost the LMF automatically to try and match it to your target curve. Alternatively, if your speaker is tri-ampable and you are using 3 amps then turn up the LMF volume or turn down the vol of the other two amps.
 

2234rew

Member
Thread Starter
Joined
Nov 24, 2020
Messages
233
The way someone has told you how to construct the XO shows that the LF has 2 low-pass filters applied to it - one at 300Hz and another at 2Khz. This seems odd to me . . . If it were me, I'd ignore the low-pass filter at 2KHz for the LF bass driver as it's already been taken care of by the 300Hz one. If a second low-pass filter is needed by the LF driver then try reducing the width of the XO instead.
Hi, this is the advice from one of the best speaker designers on the planet and how the speaker was designed with passive components.

He gave me this great starting point on how to approach DSP crossover but I don't want to bother him too much.

It was private message, so I've kept it anonymous out of respect for him helping me.

And at the end of the day, he doesn't use Audiolense anyway so I need some help from Audiolense community

Yes the 2 low pass filters which is why it is considered 2.5-way I believe

Any advice on how to achieve what I have quoted above, would be appreciated

I am happy to experiment after first trying the designers advice
 

brombo

Member
Joined
Sep 1, 2021
Messages
14
My AV System  
Main Amp
Emotiva XPA-4
Additional Amp
2 x Dayton Audio SPA1000
Computer Audio
htpc+"Pulseaudio Crossover Rack"
DAC
Xonar STX ii 7.1
Universal / Blu-ray / CD Player
Kodi+MakeMKV
Front Speakers
CBT36K
Subwoofers
2 x Dayton Audio 18" Reference Series HO Subwoofer
Video Display Device
Optoma UHZ65 Projector
Screen
Elite 120 inch
Remote Control
MX3 Air Mouse
Streaming Equipment
Google Chrome + Kodi
Streaming Subscriptions
Amazon Prime Video, MHz Choice, MPT Passport
Other Equipment
2 x HDHomerun Prime cable card tuner
What are you using for a DSP crossover (hardware/software)?
 

2234rew

Member
Thread Starter
Joined
Nov 24, 2020
Messages
233
What are you using for a DSP crossover (hardware/software)?
I have 10 channel Focusrite and Audiolense XO and Audiolense Convolver, so that is covered. I already have 3-way DSP DIY speakers.

I just need some assistance with:

1. how to do these shelf filter?
2. And how to apply both low pass and shelf to the midrange (LMF)?
3. And 2kHz low pass for both LMF (midrange) and LF (woofer)?

In Audiolense XO obviously.

It's a bit more complex than I'm used to.
 

brombo

Member
Joined
Sep 1, 2021
Messages
14
My AV System  
Main Amp
Emotiva XPA-4
Additional Amp
2 x Dayton Audio SPA1000
Computer Audio
htpc+"Pulseaudio Crossover Rack"
DAC
Xonar STX ii 7.1
Universal / Blu-ray / CD Player
Kodi+MakeMKV
Front Speakers
CBT36K
Subwoofers
2 x Dayton Audio 18" Reference Series HO Subwoofer
Video Display Device
Optoma UHZ65 Projector
Screen
Elite 120 inch
Remote Control
MX3 Air Mouse
Streaming Equipment
Google Chrome + Kodi
Streaming Subscriptions
Amazon Prime Video, MHz Choice, MPT Passport
Other Equipment
2 x HDHomerun Prime cable card tuner
I am afraid I am only familiar with programming a mindsp openDRC-DA8 or Camilla software using a sound card (ASUS Xonar Essense STX ii 7.1) on a linux pc. I also use REM to measure the speaker response. I abandoned Windows long ago although these days Apple has taken its place as the Evil Empire. I guess you would call my system a 2.3 system configured as stereo with each speaker having a 3-way dsp crossover. The tower speakers are CBT36K's designed by Don Keele for Part-Express (no longer in production). Here is a link to Don Keele's web site for the theory - Don Keele - Constant Beamwidth Transducers

hometheater.jpg
 

juicehifi

Audiolense
Staff member
Joined
Feb 5, 2018
Messages
424
You can either do this with very wide crossovers ... or you could do it with driver overlap enabled ... where you can lowpass at at a high frequency and high pass at a lower. I believe a combination of the two should get you there. Audiolense will level it out no matter what.

Me personally I prefer regular crossovers where high pass and low pass have the same properties. They match up perfectly in the time domain. You will get a perfect global result also with driver overlap and different slopes on high pass and low pass, but the drivers will not work as perfect together as with a regular xo. This scenario is the same with analog crossovers, btw, but the time domain behavior is rarely emphasised as much there as it is here. And it is NOT a big deal, but big enough to give it a chance.

So if I were you , I would try to just get in the ball park of the speaker designer's idea by using a wide crossover.... at least as a starting point. If that doesn't turn out as planned ... opt for a driver overlap solution.
 

jjazdk

Member
Joined
Aug 17, 2018
Messages
72
It is not odd, but a common way to construct a 2.5 way passive loudspeaker. Often a shelving filter is not neccessary, as the lowpass filter for the bottom woofer (with the lowest frequency range) is chosen such that it accounts for the baffle step of he enclosure.

The way someone has told you how to construct the XO shows that the LF has 2 low-pass filters applied to it - one at 300Hz and another at 2Khz. This seems odd to me . . . If it were me, I'd ignore the low-pass filter at 2KHz for the LF bass driver as it's already been taken care of by the 300Hz one. If a second low-pass filter is needed by the LF driver then try reducing the width of the XO instead.

Regarding the shelf filter, I would think that the correction filter will boost the LMF automatically to try and match it to your target curve. Alternatively, if your speaker is tri-ampable and you are using 3 amps then turn up the LMF volume or turn down the vol of the other two amps.
 

brombo

Member
Joined
Sep 1, 2021
Messages
14
My AV System  
Main Amp
Emotiva XPA-4
Additional Amp
2 x Dayton Audio SPA1000
Computer Audio
htpc+"Pulseaudio Crossover Rack"
DAC
Xonar STX ii 7.1
Universal / Blu-ray / CD Player
Kodi+MakeMKV
Front Speakers
CBT36K
Subwoofers
2 x Dayton Audio 18" Reference Series HO Subwoofer
Video Display Device
Optoma UHZ65 Projector
Screen
Elite 120 inch
Remote Control
MX3 Air Mouse
Streaming Equipment
Google Chrome + Kodi
Streaming Subscriptions
Amazon Prime Video, MHz Choice, MPT Passport
Other Equipment
2 x HDHomerun Prime cable card tuner
If you are still interested in understanding shelf filters here is a good reference -
Shelf Filters
One of the confusing things about shelf filters is you can specify a Q or a slope to define the filter. The highest Q you want to use is 0.707. Any higher and you get peaks in the filter response instead of a shelf.
 

juicehifi

Audiolense
Staff member
Joined
Feb 5, 2018
Messages
424
If you are still interested in understanding shelf filters here is a good reference -
Shelf Filters
One of the confusing things about shelf filters is you can specify a Q or a slope to define the filter. The highest Q you want to use is 0.707. Any higher and you get peaks in the filter response instead of a shelf.
Thank you but not so interested ( no pun intended) All those public eq filters are special versions ov biquads, which are IIR filters with four coefficients. Some 10 years ago I coded a gui where I could make peaking filters, dipping filters, XO-s and anything inbetween, below, over, left or right. There is a lot of possibilities outsude what is surfacing in even advanced GUIs, but I found absolutely nothing there that extended the opportunities to do something interesting.
I am confident that your speaker designer will agree with me if or when (s)he takes the time to get on top with FIR based correction.

Audiolense is not designed to mimic biquad behaviour in any shape. Life is too short.
 

brombo

Member
Joined
Sep 1, 2021
Messages
14
My AV System  
Main Amp
Emotiva XPA-4
Additional Amp
2 x Dayton Audio SPA1000
Computer Audio
htpc+"Pulseaudio Crossover Rack"
DAC
Xonar STX ii 7.1
Universal / Blu-ray / CD Player
Kodi+MakeMKV
Front Speakers
CBT36K
Subwoofers
2 x Dayton Audio 18" Reference Series HO Subwoofer
Video Display Device
Optoma UHZ65 Projector
Screen
Elite 120 inch
Remote Control
MX3 Air Mouse
Streaming Equipment
Google Chrome + Kodi
Streaming Subscriptions
Amazon Prime Video, MHz Choice, MPT Passport
Other Equipment
2 x HDHomerun Prime cable card tuner

Ofer

New Member
Joined
Mar 15, 2021
Messages
69
My AV System  
Preamp, Processor or Receiver
miniDSP 4x10hd
Main Amp
Emotiva XPR200 midrange amp
Additional Amp
Crest audio 2001A bass amp
Other Amp
Rotel RA930ax twitter amp
Computer Audio
Sony Bravia android TV
DAC
miniDSP 4*10HD
Front Speakers
Andromeda MkII
Screen
Sony bravia 65XF9005
Streaming Subscriptions
Deezer HiFi
Other Equipment
Marantz original 5E CD
Thank you but not so interested ( no pun intended) All those public eq filters are special versions ov biquads, which are IIR filters with four coefficients. Some 10 years ago I coded a gui where I could make peaking filters, dipping filters, XO-s and anything inbetween, below, over, left or right. There is a lot of possibilities outsude what is surfacing in even advanced GUIs, but I found absolutely nothing there that extended the opportunities to do something interesting.
I am confident that your speaker designer will agree with me if or when (s)he takes the time to get on top with FIR based correction.

Audiolense is not designed to mimic biquad behaviour in any shape. Life is too short.
If you could eloborate on the xover filter design it would be greatly appreciated. A lot of "common" xover filters are likwithz reihly (or others) Xdb/octave (12db, 24db etc). In the help file the AL filters are designated just as x_octave. 1octave, 0.5octave, 3octave and so on. How is that translated to the slope of the octave. For example how many db/octave slope is a 1octave slope in AL?
Thanks
 

brombo

Member
Joined
Sep 1, 2021
Messages
14
My AV System  
Main Amp
Emotiva XPA-4
Additional Amp
2 x Dayton Audio SPA1000
Computer Audio
htpc+"Pulseaudio Crossover Rack"
DAC
Xonar STX ii 7.1
Universal / Blu-ray / CD Player
Kodi+MakeMKV
Front Speakers
CBT36K
Subwoofers
2 x Dayton Audio 18" Reference Series HO Subwoofer
Video Display Device
Optoma UHZ65 Projector
Screen
Elite 120 inch
Remote Control
MX3 Air Mouse
Streaming Equipment
Google Chrome + Kodi
Streaming Subscriptions
Amazon Prime Video, MHz Choice, MPT Passport
Other Equipment
2 x HDHomerun Prime cable card tuner
Camilladsp does implement FIR filters but you would need a separate program to calculate the coefficients -

Camilladsp Filters
 

juicehifi

Audiolense
Staff member
Joined
Feb 5, 2018
Messages
424
If you could eloborate on the xover filter design it would be greatly appreciated. A lot of "common" xover filters are likwithz reihly (or others) Xdb/octave (12db, 24db etc). In the help file the AL filters are designated just as x_octave. 1octave, 0.5octave, 3octave and so on. How is that translated to the slope of the octave. For example how many db/octave slope is a 1octave slope in AL?
Thanks
The al filter does not have constant slope. They are very shallow towards 0 dB and very steep towards silence. Therefore, they are described by width instead of slope.
 
Top Bottom