A multi-way speaker design around the EXAR 400 horn

[Vineethkumar01]

I have got the EXAR 400 horns made for experimentation purposes.
In this thread, I plan to discuss the multiway speaker system design that evolves around this horn..

As per current plan

Drivers for horn: BMS 4550, Rosso 65 CDN-T with a custom 3D printed 1inch adaptor
Driver for Mids: Faital Pro 15PR400
Driver for Sub duty: SB audience NERO SW800

 

[Vineethkumar01]

Details about the EXAR 400 horn/waveguide

ATH - Advanced-Transition Horns

Advanced Transition Horns

www.at-horns.eu

 

[Vineethkumar01]

My version of the horn built by @sadik

Horn 3D printed in ABS in pieces


Steps in assembling and finishing the horn





And finally




Thanks a lot to @sadik for this

 

[Vineethkumar01]

Here is a pic of the waveguide resting on top of a cabinet housing 2 x Satori WO24P 9.5inch woofers (just for scale)..
Ultimately, these horns will not be used with the above mentioned drivers handling the low end.

For that, I will be using a 15PR400 driver from around 100Hz to 600-700Hz and an SB audience NERO 15SW800 driver handling subwoofer duties https://www.sbaudience.com/index.php/products/subwoofers/nero-15sw800/

Proposed modular system bass & mid cabinets looking something like this (at least to start with) (Ignore the colors. They have changed)



So that I can always flip them around if needed..

 

[Vineethkumar01]

Some measurements of the BMS 4550 CD on EXAR 400 horn
Measurements taken 1m away from horn mouth (gated at 4.1ms)

On axis frequency response and impedance measurement together

VituixCAD plots
Normalized directivity computed with reference axis as 10 degrees off axis

 

[Vineethkumar01]

Here is the data for SB audience Rosso 65CDN-T 1.4inch exit CD on the EXAR 400 with a 3D printed throat insert to make it a 1inch exit

In below plots, please ignore the absolute SPL levels. The seem low around 50 to 60dB SPL in plots since I had not done SPL calibration for the mic (ISEMcon EMX-7150). In reality they should be hanging around at least 80+ dB

Angular measurements upto 90 degrees

On axis response + impedance curve

VituixCAD plots

I just wish that break up was a bit milder.. (Obviously, not because I can hear it, but just so that it might look nicer to the eyes )

 

[Vineethkumar01]

But here is a performance comparison between my measurements of the Rosso 65CDN-T and the BMS 4550 driver on the EXAR 400 horn.

Measurement set up: The aim was to measure different parameters so that both the drivers when attached to the horn, are producing about the same SPL level around the 1-2kHz region. So, I adjusted the input to the drivers such that it resulted in 86dBSPL at 1m, resulting in the following frequency response curves produced at 40cm away from the horn mouth.

Raw frequency responses

BMS 4550: Distortion plot

Rosso 65CDN-T: Distortion plot

Responses after drivers are EQd flat from 700Hz up (no additional high pass filter added)

BMS4550: Spectrogram once EQd flat

Rosso 65CDN-T: Spectrogram once EQd flat

Based on the above data, I think both drivers are good on this horn. They can be crossed over steeply around 600Hz I think. But the low end performance especially below 1kHz looks better on the Rosso 65 CDN-T. There is no distortion hump for it like the BMS. The top end performance above 13kHz looks marginally better on the BMS in the spectrogram since the breakup resonance seems a tiny bit more subdued comapred to the Rosso. But in actual listening, I doubt whether that will matter to some one. In fact people may even like it..

 

[rwnano]

Very good engineering

 

[sadik]

You are doing great job @Vineethkumar01

 

[prem]

Awesome. Looks really interesting. How efficient do you estimate the speaker to be?

 

[Vineethkumar01]

Awesome. Looks really interesting.

Thanks..

How efficient do you estimate the speaker to be?

I guess you are referring to final speaker sensitivity number.
This speaker will most probably be DSP crossovered. So overall sensitivity will not be much of an issue..

But in the case of a passive crossover, the sensitivity will be determined by the bass+mid driver given that the CD has close to 110dBSPL/2.83V/1m. On this horn, due to equalization, we will lose about 10dB of it. So the final CD on horn sensitivity will be above 95dBSPL.

It is probably not a good idea to cross over the subwoofer around 80 to 100Hz with passive components. So the sub will anyway be active.

Now the overall efficiency is determined by the faital pro 15pr400 driver that has 99dB sensitivity on paper. Assuming full baffle step compression, the final speaker sensitivity will hopefully be above 93 dB

 

[Yelamanchili manohar]

@Vineethkumar01 ...this project and the proposed speaker are looking gorgeous...and the measurements are excellent too. Please keep updating this thread with lots of build pics to drool upon. I bet it will be one beautiful speaker to both look and listen too

All the very best

 

[Vineethkumar01]

I had been kept out of audio activities again due to work and family health issues.
But this morning I got some free time, and I quickly cobbled up a quick system out of my Satori WO24P-8 woofers & the SB audience Rosso 65CDN-T.
DSP active two-way with DSP and amp duties handled by the Zoudio board (https://zoudio.com/)

Here is a quick view of the specs (ignore the amp gains on the crossover pic below)



How does it sound like..?

Here are two quick video clips shot on my mobile phone from close to MLP
Please be careful with volume )

I hope this at least gives a vague idea of the system's performance.
In real-life listening, the system blows the socks and then some other things off even at low volumes (as in the video).
The system is just cruising and has incredible dynamics and clarity.
Just mindblowing
Well, I may need to take care of some room modes and a bit of fine-tuning.. but that is work for another free day. As of now, I am really enjoying what I am hearing

 

[Vineethkumar01]

Speaker response around MLP after a bit of room EQ.

I have not yet gone and done any all out room EQ through, keeping in mind that this is a temporary set up and due to lack of time.
But I have been listening to the system for short durations eatleast once in two days.
With this EQ, it sounds even better than before and my overall opinion about the sound haven't changed. It is awesome..

This is mostly pointless but here is a sample recording just for fun

 

[Decadent_Spectre]

Why is your room not covered from floor to ceiling in glasswool? Honest question as this should help you.

 

[Yelamanchili manohar]

I had been kept out of audio activities again due to work and family health issues.
But this morning I got some free time, and I quickly cobbled up a quick system out of my Satori WO24P-8 woofers & the SB audience Rosso 65CDN-T.
DSP active two-way with DSP and amp duties handled by the Zoudio board (https://zoudio.com/)

Here is a quick view of the specs (ignore the amp gains on the crossover pic below)
View attachment 83851
View attachment 83852

How does it sound like..?

Here are two quick video clips shot on my mobile phone from close to MLP
Please be careful with volume )

I hope this at least gives a vague idea of the system's performance.
In real-life listening, the system blows the socks and then some other things off even at low volumes (as in the video).
The system is just cruising and has incredible dynamics and clarity.
Just mindblowing
Well, I may need to take care of some room modes and a bit of fine-tuning.. but that is work for another free day. As of now, I am really enjoying what I am hearing

Sounding lovely,,,even over the mobile phone microphone and youtube compression on top, the vocals still seem very pure with excellent clarity and separation. Was not one of those simple easy audiophile tracks played at shows. There was quite a bit going on in the track, and it was all very coherent in the end. Bet it sounds a lot lot better in person ...enjoy

 

[Decadent_Spectre]

Just had a look at the youtube clip. What is the system frequency and phase response when this clip was made?

 

[Yelamanchili manohar]

Just had a look at the youtube clip. What is the system frequency and phase response when this clip was made?

Vineeth did post graphs for frequency and phase response in his above post.

 

[Decadent_Spectre]

Vineeth did post graphs for frequency and phase response in his above post.

In the most recent post with the youtube clip I see only a frequency response graph. I am clarifying if the posted graph is applicable to the youtube clip.

 

[Vineethkumar01]

Thanks @Yelamanchili manohar & @Decadent_Spectre and others for all the comments and suggestions.

First of all, I live in rented accommodation, and the speakers are placed in the living room, which is as good as an acoustical nightmare.
Instead of the left-side wall, there is a full glass panel (in my latest recording the sound of glass shaking can be heard during the initial bass drop.. ), the size of a wall. On the right side, the wall is about 4m+ away, So there is no scope for room treatment here, except something that can be placed in the wall behind the sofa where I sit.
I don't like this at all, and it makes my speakers sound worse compared to their true capabilities. However, I have to make do with it for now.

Secondly, regarding the validity of the frequency response for the recording position, here is a comparison of frequency responses (trying for SPL match around the 1kHz region) at at two different locations about 2 feet apart, while sitting on the couch (but moving more off-axis to the horn)


The recording mic was positioned somwhere in between the above mentioned 2 locations. Therefore I estimate the frequency response at the recording loction to be something in between the above two responses.

This system is not yet complete. The 15PR400s and the SB NERO 15SW800s haven't got their final boxes made yet. This current system was cobbled up so that I could experience how these horns sound like..
The objective of the final system is to have directivity control (at least to some extent) starting right from100Hz (cardioidish radiation pattern) achieved using DSP EQ dual woofer system, meets the horn around 600 to 700 Hz after which the directivity control aspect is taken over by the horns. The horns have a relatively narrow beamwidth (about 70 degrees max) compared to the current trend of having speakers with 100+ degrees of beamwidth. What this does is it controls the direct-to-reflected sound ratio in the room to some extent. Here are some comparisons using measurements of the horn and woofer systems

Pic showing horn beamwidth across the spectrum

Pic showing the beamwidth that can be achieved using cardioidish radiating 15inch dual woofer system


Now, compare the above plot to the beamwidth of my current Satori dual woofer system below


Comparing the above two graphs, we see that in the top plot (for dual 15-inch woofers), significant attenuation of the radiation happens beyond 120 degrees due to nulls forming in the 100 to 350Hz region. Notice that the attenuation is of the order of about 15dB+ for this radiation towards the back. This is the trick to be used for getting the front wall interference significantly down compared to my current system

How does the directivity blend happen between the dual 15inch woofer system and the EXAR 400? Here is a pic showing that

Notice the wide overlap between the green curve and the red curve.. That gives a lot of flexibility with crossover..
They were really made for each other..

Adding more room treatment to the region where the horn is doing its duty might even be detrimental to soundstage-related aspects. Here is a spectral decay plot from the MLP. Above 4kHz or so, we already have energy decayed enough due to the high directivity of the horn but below that, some room treatment should help (if it was feasible) with more decay and reducing peak energy spread due to reflections. So a delicate balancing has to be done with this system + room treatment to not loose too much treble extension while making right/get rid of some of the junk down below


All these workarounds using directivity tricks might help improve system performance but probably never achieve 100% of what a dedicated treated room can do.. All that room "noise" reduction including all the flutter echo and the reflections. Taming down the bass to some extent etc etc..
Alas, room treatment is out of the picture for now. Someday, when I have my own home, I shall have a dedicated listening room.. Till then I have to make do with all kind of tricks and band aid tweaks...

All that said, how does the system sound in this bad room at the moment. They are amazing.. Best system I have had so far.. I love it to bits..
(Biological signal processing done by our ear-brain system does a lot of work at that.. )