The Endgame: PureBliss Multiway Loudspeaker System

[Vineethkumar01]

I have been at this loudspeaker designing/making game for a while now..
Have been through quite a few 2 way, 3 way, 2.5 way, 3.5way, and 4 way loudspeaker systems with varying amounts of controlled directivity.

In my experience so far, the speaker configuration that sounded the best in my place in a nearfield application is my 3-way cardioid system with Sica 5.5inch coaxial driver + Wavecor 8inch subwoofer system.

W.r.t farfield listening I have two choices,
1) A 3 way system dual 15 inch cardioid bass-low mid system partnered to a relatively narrow horn above 900Hz. I like this system for its dynamics capabilities. It is an intense experience. This system is still evolving and may end up having bigger horn tops in future

2) A 4 way system with the same bass module as above (dual 15inch cardioid) but partenered at the top by a 2 way top module containing the SB15CAC midwoofer + SB26CDC tweeter.. This is a relatively wide radiating system that is fun to listen to and allows relaxed listening sessions..

All the above systems in various configurations have been documented in different threads on this forum..

Now that it is a new year, I thought of a new project..
In this one, I am going to apply everything that I have learned over the years w.r.t loudspeaker design and more importantly what I have learned about my preferences w.r.t music choices/genres that I listen to and the kind of presentation that I like... A very slow process of treating the room appropriately is also going on in parallel with all this.

By now I have 4 x 15inch woofers (2 x 15PR400 and 2 x SB audience NERO SW800) and 4 x 9.5inch Satori WO24P woofers competing for playing bass and low-mid range in my place. So the mids and highs will be the focus of this new system. So for that part, I decided to skip to the (my) end game..

I call this the PureBliss (Purifi + Bliesma) system partly because of the drivers involved in this project
For the mids, I chose the following driver: https://ptt.purifi-audio.com/shop/p...,4120,4121,4122,4123,4124,4125,4126,4127,4128

I think I need not speak more about this driver. But for the sake of completeness, it is an ultra-low distortion, relatively high sensitivity midrange driver

For the highs, I chose the following driver: https://hificompass.com/en/reviews/bliesma-t34a-4-34mm-alumag-dome-tweeter

It is the reigning king in large dome tweeters with a wide radiation pattern and very high breakup for a non-beryllium diaphragm..

I could have gone for a beryllium tweeter from Bliesma but I chose this one because it has some very special properties. The most important is that it can be put in a very shallow waveguide with an ultra-wide, controlled directivity configuration.

Here are some pics:

 

[Vineethkumar01]

I have already designed the waveguide.. Here is the predicted polars from BEM simulations:
This is a 140mm diameter 16mm deep waveguide for this specific tweeter


Now comes the highlight: A total double-sided beamwidth (6dB beamwidth) of 140+ degrees..

 

[Vineethkumar01]

The cabinet design (size/shape) is being studied for the best performance with these driver choices so it is not yet finalized.
But this 2-way system will be crossed over below 200Hz, most probably to the 4 x 15inch woofer system radiating in cardioid mode..
The 2way top module will most probably have a passive crossover and will be powered by (most probably) a Purifi Eigentakt amplifier..
The crossover between the top module and the 15inch woofers below will be active..
However, all these details are evolving at the moment so I will update this thread as and when the system design reaches significant milestones.
Those interested, watch this space..

 

[Yelamanchili manohar]

Wow.... the choice of drivers is out standing . Both the purifi and Bliemsa are current State of the art drivers. Even the Satori WO24P is an out standing driver if utilised in this build. And the Nero is a proper beast

So I guess the plan is to have the purifi 6.5 Incher from 200 hz upwards, but any reason why not from 400hz. And use the WO24P from say 80 to 400hz. A bigger driver doing the upper bass and lower mid range might be more fuller sounding with more body and dynamics. Just trying to pick your stream of thought thats all

And finally the wave guided Bliesma T34 is showing some excellent directivity. Never seen anything that steady from 1 khz onwards. Guess your goodselves will have a lot of liberty crossing over the purifi to the tweeter then.




Coming to the purifi eigentakt modules, are you going to get the power supplies and the amp modules and then build them yourself. Or is the plan to procure a multi channel purifi amp from the likes of buckeye or VTV.

Too many questions due to my half baked knowledge...but I will hold on till later . But please keep posting your choice of drivers and crossover points and cab design along the way, so that folks like me with an interest in DIY can also learn something along the way

Iam subscribed to this build @Vineethkumar01 . Please keep us posted with the progress and all the very best

 

[Vineethkumar01]

Thanks @Yelamanchili manohar
I may use the WO24Ps as well in this build.. It is just that the bass portion of this build is not decided yet. Regarding crossing the purifi over at 200Hz, it is tentative and the actual crossover might happen somewhere around 300+ Hz as well depending upon directivity matching etc.. But the purifi is a very capable driver which I think can handle 110dB SPL/1m with a second-order highpass at 200Hz..

Regarding amp, my two choices are Hypex Nilai 500 and Purifi Eigentakt. Both are costly (for me) and have similar power output and other specs .. So, I am slowly identifying my own requirements and finding out which one I should get.. the amp procurement will be only done in the last stage of this project (I don't know when it will happen ). So I hope I will know better before buying one. At this point, my thoughts are that the amp will not be a complete DIY build. It can be a full kit that can be easily assembled as from here: https://www.diyclassd.com/products/diy-amplifier-kits/nilai500diy-250w-stereo-power-amplifier-kit
or a fully built eigentakt from here: https://www.audiophonics.fr/en/power-amplifiers-c-6306.html/s-44/brand_2-audiophonics
Buckeye and VTV may also be better choices but I haven't finalized on anything yet..

 

[theaudioproject]

I just wanted to say how much I appreciate your thread on diyaudio. Your insights and detailed explanations are truly inspiring.
As someone who's keen on exploring and learning more about speaker design, I would love the opportunity to connect.
If you're ever open to it, I'd be thrilled to meet and discuss more about your projects and perspectives.

 

[Vineethkumar01]

I just wanted to say how much I appreciate your thread on diyaudio. Your insights and detailed explanations are truly inspiring.
As someone who's keen on exploring and learning more about speaker design, I would love the opportunity to connect.
If you're ever open to it, I'd be thrilled to meet and discuss more about your projects and perspectives.

Hi..
Thanks..
Sure we can connect offline.. You can PM me if needed

 

[sadik]

Hats off to your dedication Bro .... My Salute to you.

 

[Yelamanchili manohar]

Thanks @Yelamanchili manohar
I may use the WO24Ps as well in this build.. It is just that the bass portion of this build is not decided yet. Regarding crossing the purifi over at 200Hz, it is tentative and the actual crossover might happen somewhere around 300+ Hz as well depending upon directivity matching etc.. But the purifi is a very capable driver which I think can handle 110dB SPL/1m with a second-order highpass at 200Hz..

Regarding amp, my two choices are Hypex Nilai 500 and Purifi Eigentakt. Both are costly (for me) and have similar power output and other specs .. So, I am slowly identifying my own requirements and finding out which one I should get.. the amp procurement will be only done in the last stage of this project (I don't know when it will happen ). So I hope I will know better before buying one. At this point, my thoughts are that the amp will not be a complete DIY build. It can be a full kit that can be easily assembled as from here: https://www.diyclassd.com/products/diy-amplifier-kits/nilai500diy-250w-stereo-power-amplifier-kit
or a fully built eigentakt from here: https://www.audiophonics.fr/en/power-amplifiers-c-6306.html/s-44/brand_2-audiophonics
Buckeye and VTV may also be better choices but I haven't finalized on anything yet..

Thanks for sharing your thoughts. I did consider purifi eigentakt modules for a multi channel power amp ( I read that the filter setup for hypex amps had a learning curve, but I could be wrong, so over looked them ). But finally decided in favour of using 6 Fosi V3 mono blocks for a start. Will be easy to move them on, for not much loss should I feel the need to upgrade. But I feel they are very decent for a start, the modest price not with standing.

I will be waiting with a lot of interest, to see how the bass end shapes up, with that enviable collection of drivers vying for a place . If both the WO24P and Nero are 4ohms version, I'd be very tempted to use twin WO24P from 80 to 300 hz and twin nero below 80 hz. Though it might be an overkill depending on room size of course. But then this sounds like a "Go big or Go home" build

 

[Vineethkumar01]

@Yelamanchili manohar : The goal/theme with this system is wide controlled directivity with ultra low distortion and high dynamics capability.
The advantage of my dual 15inch woofer module is that it gives cardioidish directivity all the way down to 100Hz.. Unless I build a brand new concept and bass module using WO24Ps, I wont be able to get that level of directivity control with this system..
Dont believe me?
Here is the concept overall 4 way system using real polar measurements of my dual 15inch system (15PR400 & NERO SW800) + simulated polars for the waveguided tweeter and purifi mid all stitched together with a prototype crossover.




It is all about balancing energy radiated into space, if we allow for abrupt changes in directivity over a short range of frequencies especially above 400Hz, it will make itself known/present allowing one to not focus on other parts of the spectrum while playing music.
This has been my experience with high directivity horns partnered with direct radiating dual Satori woofers. There was a 5ish dB change in directivity over and range of about 400Hz to 2 kHz in that system... The result was extra detailed vocals but not allowing one to focus on the fine details in upper treble during music playback.. It will all be there in the music, but it is hard to notice/hear it because the brain gets locked on/focusses to the more energy sprayed out in the other range of frequencies. Or at least this is my hypothesis.

This is the reason why I am trying to make the Sound Power DI in above CTA 2034 curve as smooth and as much "jump" less as possible/slowly climb up (the inevitable DI climb up with these kind of drivers).. If you check above plot, it is hardly a 2dB change from 150Hz to 20 kHz.

Now compare that with the sound power DI in the below system (Dual Satori WO24P + EXAR 400 horn)


But all that said this system design is not yet frozen so changes may come w.r.t overall configurations..

 

[Vineethkumar01]

Regarding box design,
Let us start with this..
Firing up the BEM simulations for the woofer and tweeter..

 

[Yelamanchili manohar]

@Yelamanchili manohar : The goal/theme with this system is wide controlled directivity with ultra low distortion and high dynamics capability.
The advantage of my dual 15inch woofer module is that it gives cardioidish directivity all the way down to 100Hz.. Unless I build a brand new concept and bass module using WO24Ps, I wont be able to get that level of directivity control with this system..
Dont believe me?
Here is the concept overall 4 way system using real polar measurements of my dual 15inch system (15PR400 & NERO SW800) + simulated polars for the waveguided tweeter and purifi mid all stitched together with a prototype crossover.
View attachment 88577
View attachment 88578
View attachment 88579

It is all about balancing energy radiated into space, if we allow for abrupt changes in directivity over a short range of frequencies especially above 400Hz, it will make itself known/present allowing one to not focus on other parts of the spectrum while playing music.
This has been my experience with high directivity horns partnered with direct radiating dual Satori woofers. There was a 5ish dB change in directivity over and range of about 400Hz to 2 kHz in that system... The result was extra detailed vocals but not allowing one to focus on the fine details in upper treble during music playback.. It will all be there in the music, but it is hard to notice/hear it because the brain gets locked on/focusses to the more energy sprayed out in the other range of frequencies. Or at least this is my hypothesis.

This is the reason why I am trying to make the Sound Power DI in above CTA 2034 curve as smooth and as much "jump" less as possible/slowly climb up (the inevitable DI climb up with these kind of drivers).. If you check above plot, it is hardly a 2dB change from 150Hz to 20 kHz.

Now compare that with the sound power DI in the below system (Dual Satori WO24P + EXAR 400 horn)
View attachment 88580

But all that said this system design is not yet frozen so changes may come w.r.t overall configurations..

Thanks got your point and what you are trying to achieve here

That is awesome directivity control from 100 hz onwards. I did read in your previous build about the cardoid bass directivity. Very impressive indeed. Now I will just sit in the audience and watch the build, without further interruptions

 

[Vineethkumar01]

So this is what is possible with both the Purifi 6.5inch and the Bliesma T34 in a shallow waveguide (150mm diameter, 16mm deep).


Cabinet dimensions: Width x Depth x height = 270mm x 200mm x 394mm
The height dimension can be reduced to 344mm by reducing the rounding at top and bottom to 30mm each instead of 50mm in the current pic. It will definitely have a minor impact on the vertical directivity.

At least the width dimension & 50mm rounding are needed for proper edge termination of the waveguide & avoiding midrange narrowing with the waveguide.

Tweeter in waveguide raw response curves (ignore the peaks around 1164Hz. It would be a simulation issue):



Woofer in waveguide raw response curves (ignore the peaks around 1164Hz. It would be a simulation issue):



The full speaker response with a prototype crossover






What is missing in the modeling is the purifi driver mid break up region and the EQ required to tame it..
But it very manageable with this driver

 

[Vineethkumar01]

I think I couldn't have asked for better response curves with this driver combo..
So ideally the next step would be to get a prototype cabinet & some measurements I guess..

 

[grindstone]

It's not a race, you are entitled to cogitate a while (unless you are driven to do it--then it is a race). No offense, but your meshes are a lot better, now . From appearances, you have really gone through the money on this stuff--my wish for your new year is that you find a way to keep on your path but to do so more economically.

 

[Vineethkumar01]

Hi @grindstone
Wishing you too a very happy new year..
Yes.. These drivers have cost me more money than I ever wanted to spend on audio. But I had to get them..
I have been planning to write about some of the non-technical aspects/complex reasons behind this project as well.
Now I am writing down a few below..

1) I wanted to have a reference system for myself in terms of the quality of drivers/amplification that I would use in a project. This is also to establish/understand a benchmark in system performance achievable. These references might change in a few years' time as technology moves on, but I don't know if I will be doing speaker projects at this pace by that time due to personal reasons..
One thing I really want is to have a nice system to play some music on every day after work for something like 30 minutes at relatively low volumes.

2) I started the speaker-making journey with the direct radiating 3-way speaker. Due to the relatively not best driver/waveguide choices for the concept speaker I had in mind at the time, it didn't turn out to be the speaker that would make me stop making speakers for a while.. I went on and on.. modifying the concept by including/replacing them with coaxial drivers, short waveguides, relatively deeper, bigger waveguides, and more recently with MEHs, and cardioid radiating concepts etc.. I have implemented/measured all these to the best of my knowledge, abilities etc.. Made tens of iterations for driver combinations and crossovers for each speaker and then measured them again and again
All this time, I have been listening to these as well and have identified a few strengths and weaknesses of each of these concepts, especially in my space.

3) From the above race in making speakers, I have identified the following as my preferences regarding/characteristics in loudspeakers I might like the best.
a) I like cardioid(ish) radiating speakers in terms of how they sound in my room.

b) I have liked the sound from short waveguides (eg: ST26KVAR with BMS 4550 & SB26CDC on small augerpro waveguide) and direct radiating bass drivers in sealed cabinets.

c) I hated the sound from ported alignments I have tried (well, I should say that I haven't heard very big horns but they are anyway not practical for my space so I am not exploring that direction).

d) I like direct radiating metal cone tweeters but not when the complete tonality of the speaker changes (especially identifiable in vocals) when I move to the side by about 20-30 degrees off-axis (eg: My Qacoustics 2020i).

e) I like those EXAR400 horns + dual 15inch woofer system when I really want to turn up the volume and just enjoy music at relatively higher volumes and when no one is at home as others at home are sensitive to the sound from that horn while they like the 4way system I made from the same bass module + a 2way top using SB15CAC + SB26CDC driver combo

f) I don't like the (relatively) lessened sense of spaciousness from my EXAR400 horns at low volumes but like the system's imaging

g) I like relaxed-sounding speakers even when the volume increases. This I was able to achieve with the above-mentioned 4-way system but not with the EXAR horn-based system. I was also able to get something similar from the ST260KVAR-based system years back.

h) MEH design needed more effort/time to be put in fine-tuning a lot of aspects that I have postponed it for a while.

i) One of the fundamental problems that I have faced with all these speakers is that I haven't had the greatest help from the acoustics of the spaces that I have put all these speakers in.. So now I am putting in a little bit of effort in that direction as well.. Now I am trying to do whatever possible w.r.t room treatment..

j) I have liked (the cheaper ones I have tried) Class D amplifiers driving the speakers playing bass but not when they drive compression drivers/tweeters at higher volumes

I have noted down these observations over some period of time hearing all these systems and have been pondering about it.. This is what drove me to choose the drivers for this project.. Based on prior experience, I have this feeling that this speaker will match my own preferences for sound for the kind of music I most frequently hear (obviously overall power response and directivity targets will play a role in this as well but I am not elaborating on it further now)..

This speaker, once done well, is what I hope will be my break from speaker projects for a while and just sit down and enjoy music..

Regards
Vineeth

 

[sadik]

This speaker, once done well, is what I hope will be my break from speaker projects for a while and just sit down and enjoy music..

The Bug has gone deep into your veins...You may need help from Scarlet Witch to get it out.

 

[Vineethkumar01]

I did try out creating a mono speaker out of this system for listening impressions and study the performance both objectively and subjectively. I am yet to get the waveguide printed so the Bliesma tweeter is currently used in direct radiating configuration in a shaped cabinet.
Here are some pics and latest crossover configuration details:

Prototype cabinet with Purifi and Bliesma drivers forming a 2-way top module for the dual 15inch subwoofer-woofer system.
The 2way top cabinet is 3D printed.




Next steps would be to print and test the waveguide.
If I like it, I will create the other speaker as well for stereo experience.
And maybe think about a nice final cabinet for the 2way top as well

To summarize the subjective listening experience. I really like this system so far.
For nitpicking any faults, there are a couple of places to improve, like getting rid of the high-frequency diffraction with the waveguide and lowering the excess group delay around 100Hz to less than 2ms.