High WAF Dynamic Speaker System Build

[dr suad]

Hi,

This is a build thread of a speaker system for my living room built on the unitized image wavguide design from Patrick Bateman: https://www.diyaudio.com/community/threads/unitized-image-control-waveguide.319698/page-16

The waveguide being used is constant directivity and offers about 360Hz-20khz range at 96db/w/m using 4 midranges and one tweeter. I went off this design because one of the best speakers I ever heard were the Lambda Acoustic Unity's (licensed from Tom Danley). They did everything right, so this design has similar performance in a smaller waveguide.

- I need the bass cabinet to be dynamic, loud, crisp and have a wide sweet spot. My musical tastes are all over the place, rock, fusion, synthwave, jazz, etc.. Metal is the most demanding as it needs to have crisp kicks and snare along with the wide bandwidth of the rest of the instruments. To find out what freqeuncies need special attention, I took a spectrum analysis of a demanding track "God's Equation" by Pagans Mind as shown below:

As you can see, a substantial amount of musical energy is focused in between about 350hz to 40hz. Kick drums range in 40 to about 100Hz, snare peaks around 193hz, with activity up to around 425hz. Toms focus around 105 to 158hz. This explains why I always liked a higher crossover frquency in my car and never liked the 80hz, it crosses over in the middle of the kick drum. The good news as the around 300 - 400 hz, there seems to be less peaks for various types of msuic of that style, so a crossover can go right there.

- The speakers need to fit both sides of the fireplace in these areas for the WAF to be high (Wife Acceptance Factor) and would be disguised to look like a radiator (like on the left) or a cabinet of some sort. I have a space of up to about 32" long x 18"deep x 25"high. It could be up to 30" if the design has to use that height. The idea is to have the horn sit in it's own box on the top, which brings it to about 30" anyway.

That being said, these are the constraints and objectives:

1. Bass bin that covers 40hz to 400hz,
2. High sensitivity around 97+ db/w/m. Why? I don't know why, but for some reason big speakers sound more dynamic, even at lower volume levels despite the math showing the same output level.
3. Fit within an area of up to about 32" long x 18"deep x 25"high (81cm x 45cm x 64cm). That a volume of 8-10 cu. ft (235L - 283L) Must be box-shaped, this will look like a cabinet or radiator cover with paint and "creativity".
4. MiniDSP, FIR filters, Active Filters are all ok for the bass cabinet. The waveguide would ideally remain passive.
5. The waveguide and be a part of the cabinet or separate.
6. I am knowledgeable in work working to cut and glue panels.
7. sound dynamic at both lower and high volume levels. I typically listen around 85db-90db. I don't plan on blasting concert levels, but want the option.
8. I am open to any and all ideas to achieve the objectives above, breaking conventional rules is ok.

Some ideas that I have been thinking about for a while:

• Open baffle with two SB Audience Bianco-15OB350 15" Open Baffle Woofers per side. Maximum distance I can keep drivers from wall (at the baffle) would be 18". *I have tried this approach about 12 years ago with early 15" Acoustic elegance dipole woofers on sale. I remember good clean bass with one 15" woofer, so much that it occurred a single one woofer would have been ok, even being close to a wall. That was the "rule breaker" concept as it had the best bass I ever heard in terms of quality. I don't remember regarding dynamics. I had used DSp at the time with a Behringer feedback destroyer unit.
• Sealed cabinet with a 6ft. space using a single SB Audience Bianco-15OB350 15" Open Baffle Woofer Joseph Crower had good success with this, as it showed good promised with critical damping. https://josephcrowe.com/blogs/news/...y-15-2-way-monitor-using-sb-audience-products I was thinking adding resonant chambers inside to damp the impedance peaks like the Hegeman enclosure design from this thread: https://www.diyaudio.com/community/threads/3d-printed-metamaterials.360739/page-5
• Front loaded horn similar to the University Classic, but would need to be reshaped to fit the 18" depth, not sure this is practical for 40hz-400hz. Maybe something like William Cowan's Horn Sub Jr., but with a side scoop to make it front firing: https://www.cowanaudio.com/hornsubjr.html
• Karlsonator / Karlson cabinet of some sort. Freddi speaks highly of these cabinets, but it would need to lay on it's side. They don't simulate well, but I hear lots of praises for it's sound.
• Front loaded bass refelx like Altec A7, but not so large. Joseph Crowes awesome 1798 cabinet looks VERY promising to work off of, but it's too big for my space. However, maybe squashed down/ isobaric loading and with Onken Style vents / passive radiators could do it in the volume I have to work with: https://josephcrowe.com/blogs/news/bass-cabinet-no-1798 I could integrate the waveguide into the top part of the woofer horn.
• Slot Loaded open baffle, or slot loaded closed - Brings down distortion, but concerned with frequency response about 250hz (maybe not an issue?).
• Something Wild and Different - Hybrid Front loaded horn with tapped horn aka Cyclops style tapped horn? 6th/8th order band pass? Front loaded Horn with woofer feeding a Paraline lens that goes into a conical horn?

I'll be going over some simulations to see what may be possible. I would greatly appreciate anyone's input - any and every suggestion would be greatly appreciated!

 

[CinnamonRolls]

In the waveguide thread you said this:

"The midwoofers will be 4xFaital Pro 6FE100's in a sealed cabinet and narrow the beamwidth with the DNA concept."

I have a terrible memory but I think @Patrick Bateman may have said rubber surrounds fall apart in multiple entry horn applications. I think he suggested paper surrounds instead because they can withstand the abuse. Don't trust my memory on anything, ask Patrick if those Faital Pros are ok in that application.

Also, your listening room is beautiful. Anything you put in there will sound great because the environment is so cool.

 

[GM]

Altec A7 load to ~342 Hz, but Tom used TH, so if you can find some 40 Hz Fs, (40*2/400 = 0.2 Qt) drivers you can too.

 

[dr suad]

In the waveguide thread you said this:

"The midwoofers will be 4xFaital Pro 6FE100's in a sealed cabinet and narrow the beamwidth with the DNA concept."

I have a terrible memory but I think @Patrick Bateman may have said rubber surrounds fall apart in multiple entry horn applications. I think he suggested paper surrounds instead because they can withstand the abuse. Don't trust my memory on anything, ask Patrick if those Faital Pros are ok in that application.

Also, your listening room is beautiful. Anything you put in there will sound great because the environment is so cool.

Thanks! I consdiered using the 6FE100's based on Bwaslo's SmallSyns suggestion, except for 4 instead of two to use the DNA concept and raise the efficiency. I gather for good reproduction in the 40-400hz range, I need minimum phase and flat response. I remember Lambda acoustics (later aespekaers ) had GOT12 concept (God of Thunder). It used a 12" woofer with two 18" passive radiators tuned to around 20 hz. In theory, this pushed the group delay down low. I remember hearing lambda's version with two 12" woofers and the two passive radiators. What struck me was the quality of the upper bass, which is where the concept of crossing over at 300hz caught my attention. However, on demanding double bass tracks, the bottom felt a bit sloppy - maybe it was from the sheer mass of those passive radiators.

Anyway, here are my sims with (4) 6fe100's using a linkwitz transform and 35hz tuning for 5 cu. ft box. Passive radiators would have to be used. Max amplifier load is 65w, phase shift occurs 180 around 32 hz. Max SPL around 112db. In theory this should do what I want, but maybe there is something I am overlooking. The plus for this is the DNA style spacing I could use to control the beamwidth lower.

 

[dr suad]

Altec A7 load to ~342 Hz, but Tom used TH, so if you can find some 40 Hz Fs, (40*2/400 = 0.2 Qt) drivers you can too.

Not quite following this - an Altec A7 Tapped horn? My waveguide will go to 342hz already. Perhaps a 40hz-300hz tapped horn?

 

[GM]

No, was just posting some pertinent A7 FLH tuning. If wanting a TH to only 300 Hz, then driver Qt can be higher.

 

[dr suad]

Here's an Altec VOTT A7 style front loaded horn with bass reflex. Driver for this would be the 15" Faital Pro 15FH520 - 4. System Volume would be 169L, which is under the 283L requirement. Horn Mouth is 2975 cm^2, which is under the 5000 cm^2 I have to work with. The horn depth is 30cm, plus the 18cm for the driver, making it right at the 45cm depth requirement. I may find a driver that is a little narrower. Seems like it would fit the job, unless I am missing something?

 

[Baffless]

I think WAF factor should become rating in loudspeakers specsheets. Just how do define it ? 😂

 

[dr suad]

Good point! As far as WAF - it should look like there are no speakers, match the color scheme and enhance the look of the room, the latter being subjective of course! I have some aesthetic tools as disposable, acosutically transparent grills, speaker cloth, even speaker cloth that looks like materials. See the wood radiator covers as some ideas I have.
One idea I have it that I keep the white radiator cover that is on the left and get another, which I have in the attic. Hook it up so that a scissor platform could lift it up and the top of the radiator cover flips back. A flatscreen TV tv lift could be an option too.

 

[dr suad]

Sealed enclosure options - Joseph Crowe's website shows impressive performance from a single 15" SB Audience Bianco-15OB350 .

https://josephcrowe.com/blogs/news/...y-15-2-way-monitor-using-sb-audience-products

Using a small EQ boost, the requirements for frequency response would be satisfied. One woofer gives amazing performance, so why not two? Each cabinet is 76L, or 152L total. That is under the 283L requirement. Critically damped 1.7ms transient response. Total sensitivity would be 98 db/w/M. One woofer gets 121db at 400W, xmax 11mm. No wild phase changes at crossover. I may be able to space the woofers to narrow the midbass directivity to match the waveguide. It seems so ideal on paper, yet so simple.
If I had a corner, I would build that enclosure, but since I want two woofers and have my space constraints, I would need to build my own. (If I did, I'd buy his plans anyway if I used that concept).

 

[dr suad]

I forgot to include power conversion efficiency on the Altec Style horn with the Faital driver. I am guessing that efficient electrical to sound power conversion would be an important factor for dynamics, with minimum cone movement and high sound output to help maximize transients.

 

[GM]

Yes, but need to understand that it's the inductance that governs transient response.

 

[dr suad]

Here's a 0.75x scaled University Classic, this fits the dimensional constraints. Would be 30"x22.5"x18". Uses the 18Sound 12NDA520. F10 about 53hz so I would have to to bite the bullet and use a crossover with a tapped horn. That would have to be hidden in a coffee table or do the multiple sub approach...
The efficiency is over 30%! At least the horn would be front firing. As far as phase, well it's a zig zag. Maybe the phase is not too much to worry about in reality?

 

[GM]

Look at unwrapped phase.......

 

[mayhem13]

For highly dynamic chest thumping midbass, nothing beats an 18 and you’re fortunate enough to have the space required for them. A side by side pair of 12”s would also be an excellent choice……a parallel pair of 8ohm drivers per side would give you crazy efficiency.

Thats a relatively small space from your photos so I would expect some significant modes. The fact that placement won’t be flexible, your primary concern should be how you’re going to flatten things out 120hz and below. Use extensive DSP control of the bass modules. This will require a microphone and some time and understanding to dial in. You can use the DSP for the low pass filtering as well.

For the WAF, use the tilt up pocket garage door approach where your screen/cover tucks away out of sight.

Make sure you build these on legs with a bit of clearance from the floor though…..your still going to need to keep your house warm and the convection currents created by the window above on the left will still need air to be drawn in and over the radiator. If not you’ll crush what little efficiency you have already…….and heat ain’t cheap these days not to mention the poor WAF of a chilly room. A 3-4” silent computer fan would solve the issue for about $20 sucking air in under the box and blowing towards the radiator….that will keep the updraft current created by the cold window panes going.

When you build the face cover, if you plan on the historically correct punched metal, make sure to laminate it to the substrate or it’s going to rattle and resonate. Personally, I’d wrap and panel with a period correct fabric to avoid the problem completely. Get your wife involved…..let her choose the pattern and color. It doesn’t need to be acoustical in nature at all…..you’re going to tilt them up and away when listening anyways.

Not sure what your plan is going to be for the Unity’s concealment though……i suppose a tilt up and fwd type of mount could be used where the unity folded away into a compartment built in to the bass bin…….you certainly have the volume needed available. Some clever engineering could make it a one action system…..lifting the Unity could also create the pull for the bass module cover with a cable and some pulleys.

Pop Up is another solution that would work…..that could be done remotely with linear actuators…..they’re certainly cheap enough these days. My bedroom tv pops up from a slot built into the bed’s footboard…..cost me about $125 and the actuator came with the limit switches and the remote.

Good luck with your build. Sounds like a fun one for sure.

 

[Kravchenko_Audio]

Sealed enclosure options - Joseph Crowe's website shows impressive performance from a single 15" SB Audience Bianco-15OB350 .

https://josephcrowe.com/blogs/news/...y-15-2-way-monitor-using-sb-audience-products

Using a small EQ boost, the requirements for frequency response would be satisfied. One woofer gives amazing performance, so why not two? Each cabinet is 76L, or 152L total. That is under the 283L requirement. Critically damped 1.7ms transient response. Total sensitivity would be 98 db/w/M. One woofer gets 121db at 400W, xmax 11mm. No wild phase changes at crossover. I may be able to space the woofers to narrow the midbass directivity to match the waveguide. It seems so ideal on paper, yet so simple.
If I had a corner, I would build that enclosure, but since I want two woofers and have my space constraints, I would need to build my own. (If I did, I'd buy his plans anyway if I used that concept).

An interesting design. The 6 db of EQ is no small request. That driver needs to make 4 times the excursion at those frequencies to pull this off.

 

[dr suad]

For highly dynamic chest thumping midbass, nothing beats an 18 and you’re fortunate enough to have the space required for them. A side by side pair of 12”s would also be an excellent choice……a parallel pair of 8ohm drivers per side would give you crazy efficiency.

Thats a relatively small space from your photos so I would expect some significant modes. The fact that placement won’t be flexible, your primary concern should be how you’re going to flatten things out 120hz and below. Use extensive DSP control of the bass modules. This will require a microphone and some time and understanding to dial in. You can use the DSP for the low pass filtering as well.

I am completely fine with using DSP and Amplifier Power but want to get the basics on a good and sound design. I explored a bass reflex using an 18" based on your suggestion. In my area (Nashville) there are always deals to be had for prosound drivers. One is a pair of JBL E155-4 18's. I modeled a bassreflex using this. It has a hump, but I figure I can EQ that down. Interesting that the efficiency as much high in HornResp than WinISD, it looks attractive to use - by design. (BTW - if radiator is replaced, I will move it to a different location, considering under-floor heating retrofit)

 

[dr suad]

An interesting design. The 6 db of EQ is no small request. That driver needs to make 4 times the excursion at those frequencies to pull this off.

That is true, sealed are far less efficient than a horn, but you get more bandwidth. According to his tests, EQ didn't affect the already low 0.07% IMD at 90db for one woofer, adding two, I halved the required boost to each driver for the same gain. I ran some sims on HornResp for (2) 15OB350's with the EQ. Impedance went in half with two woofers in parallel. The impulse response looks about like his measurement. On design, 1w easily gets over 100db at 40Hz with 0.8mm excursion. This looks good to me and I haven't even factored in a second enclosure. Am I missing something in my sim??

 

[mayhem13]

I am completely fine with using DSP and Amplifier Power but want to get the basics on a good and sound design. I explored a bass reflex using an 18" based on your suggestion. In my area (Nashville) there are always deals to be had for prosound drivers. One is a pair of JBL E155-4 18's. I modeled a bassreflex using this. It has a hump, but I figure I can EQ that down. Interesting that the efficiency as much high in HornResp than WinISD, it looks attractive to use - by design. (BTW - if radiator is replaced, I will move it to a different location, considering under-floor heating retrofit)

Forget about the 5db bump……you’ll need to start your lowpass at 200hz or so to derive a target where both 1/4 wave distance and power compression make sense for 6” midwoofers. From 150hz down, room gain will take over….likely 6db per octave but could be more depending on construction, openings, shape and volume. Your actual in room response of your model is much flatter and more extended than the Hornresp sim.

 

[Kravchenko_Audio]

I am completely fine with using DSP and Amplifier Power but want to get the basics on a good and sound design. I explored a bass reflex using an 18" based on your suggestion. In my area (Nashville) there are always deals to be had for prosound drivers. One is a pair of JBL E155-4 18's. I modeled a bassreflex using this. It has a hump, but I figure I can EQ that down. Interesting that the efficiency as much high in HornResp than WinISD, it looks attractive to use - by design. (BTW - if radiator is replaced, I will move it to a different location, considering under-floor heating retrofit)

If you have figured out how to use Hornresp, leave WinISD at the road side. It has too many gremlins.