DIY Three Way System w/ Integrated Sub

[PGansz]

I will be building a custom three way and I've settled on integrating a sub into the same tower with a plate amp and DSP. Outer box size will be: 50-52in x 14-15in x 16-17in (HxWxD).

Initially I started out modeling and sketching SATORI textreme drivers, but I just couldn't get the low-end I wanted and the value proposition seems quite low. But I do love cars and racing and those drivers would make a cool racing livery schema. Anyway...

I think I've settled on a Dayton RSS315HF-4 sealed 70L box for the bottom end of the three way. In this process I've begun looking at medium to large coaxials for ease of implementation and all the other benefits. All the TB speakers have high distortion and seem a little wonky FR-wise. The best I've seen is W8-2123, but is rare, etc.

Can anyone recommend a linear FR, low distortion, high-enough power handling coaxial? Target is 95db at 4-5m, 1% or less distortion.

I've been perusing the 8in variety from Beyma at Parts Express - they look great but I can't find any independent measurements so far.

Any help would be great appreciated.

 

[ppataki]

I will be building a custom three way and I've settled on integrating a sub into the same tower with a plate amp and DSP. Outer box size will be: 50-52in x 14-15in x 16-17in (HxWxD).

Initially I started out modeling and sketching SATORI textreme drivers, but I just couldn't get the low-end I wanted and the value proposition seems quite low. But I do love cars and racing and those drivers would make a cool racing livery schema. Anyway...

I think I've settled on a Dayton RSS315HF-4 sealed 70L box for the bottom end of the three way. In this process I've begun looking at medium to large coaxials for ease of implementation and all the other benefits. All the TB speakers have high distortion and seem a little wonky FR-wise. The best I've seen is W8-2123, but is rare, etc.

Can anyone recommend a linear FR, low distortion, high-enough power handling coaxial? Target is 95db at 4-5m, 1% or less distortion.

I've been perusing the 8in variety from Beyma at Parts Express - they look great but I can't find any independent measurements so far.

Any help would be great appreciated.

If you are looking for low distortion I am not sure if coax drivers would be the best choice
Additionally, an 8" coax likely won't have a nice directivity curve either

I would rather consider a separate tweeter (ribbon for lowest distortion) and midwoofer using directivity-matched active digital crossover (and digital delay for time alignment)

If you stick to 8" coax, you can check out the Sica and SB options too

 

[PGansz]

If you are looking for low distortion I am not sure if coax drivers would be the best choice
Additionally, an 8" coax likely won't have a nice directivity curve either

I would rather consider a separate tweeter (ribbon for lowest distortion) and midwoofer using directivity-matched active digital crossover (and digital delay for time alignment)

If you stick to 8" coax, you can check out the Sica and SB options too

Yeah - I even considered an option of buying a Kef THX Ultra architectural unit meant for in-wall to ensure quality and reliability.

My issue with ribbon or planar tweeters is the high crossover point. Because I'm using a sub to anchor low-end in the three way design I need a mid that can play low distortion down to 150hz. Any mid that plays low can't cross up at 2.5k without directivity issues and/or high distortion.

Aesthetics matter in this build as well so I'm also looking for unity and color-ways between drivers.

Active is on the table. I am prepared to use miniDSP if required. Although originally preferred passive.

 

[ppataki]

H

Yeah - I even considered an option of buying a Kef THX Ultra architectural unit meant for in-wall to ensure quality and reliability.

My issue with ribbon or planar tweeters is the high crossover point. Because I'm using a sub to anchor low-end in the three way design I need a mid that can play low distortion down to 150hz. Any mid that plays low can't cross up at 2.5k without directivity issues and/or high distortion.

Aesthetics matter in this build as well so I'm also looking for unity and color-ways between drivers.

Active is on the table. I am prepared to use miniDSP if required. Although originally preferred passive.

Have you considered going 4 ways?
2x3 ways in the front speakers + 1 or multiple sub(s)
That is what I am doing too and that allows for greater flexibility

 

[PGansz]

I did initially but then I figured with a good A/V processor I would prefer to control subs separately for HT/LFE use.

A four way with decent size drivers plus a sub is just not going to fit in two speaker boxes. So, back to three way plus sub in lower section.

Here's a link to the coaxial I was looking at. The directivity looks good enough to EQ out a lot of those bumps.

NEW Beyma 8CX300Fe 8" Coaxial Loudspeaker 8+16 Ohm

Beyma 8CX300Fe 8" Coaxial Loudspeaker 8+16 Ohm8CX300Fe 8" Coaxial Loudspeaker 8+16 OhmThe 8CX300Fe's substantial power handling capabilities and high sensitivity enable it to deliver clear and dynamic sound output, making it suitable for demanding audio applications. The 2.5" voice coil in the...

www.parts-express.com

 

[jaakkopetteri]

Additionally, an 8" coax likely won't have a nice directivity curve either

What makes you think so?

 

[3ll3d00d]

Here's a link to the coaxial I was looking at. The directivity looks good enough to EQ out a lot of those bumps.

I have the neo version of that driver, I think the behaviour is v similar to the Fe one. The published curves are reasonably accurate albeit on a 120dB wide scale so looks much flatter than it is, it's naturally a pretty messy response due to the horn sitting in the woofer like that (but then most coax's look like a mess when measured). It's a perfectly decent driver, personally I couldn't live it with in a main system (I use it in a games room for casual tv/gaming use) as there's something a little odd about it sounds to me but ymmv. I have some radian 5208 coaxes as surrounds (which I also trialled as mains at one point) and that makes a much more pleasant sound imo. A small coax is also commonly paired with woofers above and below btw so you may want to consider that design rather than the one shown.

Results of a passive xo shown below for the beyma, not sure if you're doing it active or not but can post the xo if you want it as it's not exactly an easy driver to work with (or can show similar for the radian)

 

[ppataki]

What makes you think so?

When I was contemplating on this project I was also considering using 8" coax drivers and I was looking at various models, like:

https://sica.it/wp-content/uploads/2024/12/Z005209P-88.pdf

7½″ SATORI MT19CP-8 / paper - Sbacoustics

PRODUCT COMPARISON

sbacoustics.com

https://doc.soundimports.nl/pdf/brands/SB%20Audience/ROSSO/ROSSO-8XC250/ROSSO-8CX250-datasheet.pdf

To me the on/off-axis/polar graphs were not very appealing, hence I went for a smaller size (and then switched to separate drivers)
But of course, there might be exceptions, as always

 

[Digital_Thor]

I found a set of KEF coax from KEF R3 non Meta, model SP1753AA. They work great crossed at 2.2kHz.
Crossed at 400Hz to dual Satori WO24P-8 in closed 75 liter cabinet.
All with IRR LR24dB filters. No HP on the Satori, so that I have minimum phase challenges to my 4 subwoofers.
Usually you need to buy the Meta version to have a lower cross-over point, but I found that the non Meta 2018 R-version seems to cross lower just fine.
I would even buy a set of used R3's to just take the coax and use for my DIY, simply because I like the look and freedom to use larger woofers, to extend the response to around 60Hz in closed cabinets, rather than buying ready made KEF speakers, even though they might be fine - I did consider the R7... but DIY is also fun. You'd have to go Blade 1 to get bigger woofers

Measurements are gated just before the floor bounce and made from 0 to around 60 degrees, to get a feel of my DIY active filter work.

 

[jaakkopetteri]

To me the on/off-axis/polar graphs were not very appealing, hence I went for a smaller size (and then switched to separate drivers)

How exactly were they not appealing? All of those are great apart from some inaudible on-axis dips

 

[PGansz]

I found a set of KEF coax from KEF R3 non Meta, model SP1753AA. They work great crossed at 2.2kHz.
Crossed at 400Hz to dual Satori WO24P-8 in closed 75 liter cabinet.
All with IRR LR24dB filters. No HP on the Satori, so that I have minimum phase challenges to my 4 subwoofers.
Usually you need to buy the Meta version to have a lower cross-over point, but I found that the non Meta 2018 R-version seems to cross lower just fine.
I would even buy a set of used R3's to just take the coax and use for my DIY, simply because I like the look and freedom to use larger woofers, to extend the response to around 60Hz in closed cabinets, rather than buying ready made KEF speakers, even though they might be fine - I did consider the R7... but DIY is also fun. You'd have to go Blade 1 to get bigger woofers
View attachment 501449

View attachment 501450
View attachment 501451
Measurements are gated just before the floor bounce and made from 0 to around 60 degrees, to get a feel of my DIY active filter work.
View attachment 501453

This is exactly what I had in mind earlier is robbing some used Kef reference coax second or third hand. Excellent work!

I'm really torn between this type of design and a separate driver, three to four way system.

 

[PGansz]

I have the neo version of that driver, I think the behaviour is v similar to the Fe one. The published curves are reasonably accurate albeit on a 120dB wide scale so looks much flatter than it is, it's naturally a pretty messy response due to the horn sitting in the woofer like that (but then most coax's look like a mess when measured). It's a perfectly decent driver, personally I couldn't live it with in a main system (I use it in a games room for casual tv/gaming use) as there's something a little odd about it sounds to me but ymmv. I have some radian 5208 coaxes as surrounds (which I also trialled as mains at one point) and that makes a much more pleasant sound imo. A small coax is also commonly paired with woofers above and below btw so you may want to consider that design rather than the one shown.

Results of a passive xo shown below for the beyma, not sure if you're doing it active or not but can post the xo if you want it as it's not exactly an easy driver to work with (or can show similar for the radian)

View attachment 501446

Thank you for providing that information. I'm not super concerned with ruler-flat FR, if it can be digitally EQ'd I'm OK with a few bumps.

However, some of your more subjective thoughts are concerning. I'll take your advice and abandon the concept - they're aren't the prettiest drivers either.

Edit: I was originally doing passive but now considering active since it is just more accurate. Choices!

 

[Digital_Thor]

This is exactly what I had in mind earlier is robbing some used Kef reference coax second or third hand. Excellent work!

I'm really torn between this type of design and a separate driver, three to four way system.

Thank you.
I do want to make the cabinets nicer. This was my first build with this driver, and I had to make a quick test cabinet to see if I could actually make it play as I wanted it, and get the same smooth frequency response as KEF officially do, like you see on spinorama, and with Amir and Erin.
My goal was to build something close to KEF R900, which is the last "big" KEF speaker they made. Then I wanted a bit better drivers and from 2018 and onwards, KEF made the newer 12 gen R series, which in my view really refined the their coax to something really good.
I think you can come close with the Sica 5" coax, which I've heard in DIY, and it is good. But since I'm a little fiddly with my likings, I just had to find a KEF, since they are really technically superior in design, just look at that smooth response
Further, I think, that the coax design has given me some of the smoothes sound overall in my room. Having that slightly better controlled dispersion, really seem to play "through" the room a bit more than conventional midrange/tweeter designs, especially when it comes to dispersion at all angles.

 

[Devnull]

Have you looked at FaitalPro? They've got some nice coaxials. I've got a 8HX150 to play with, just haven't had the time.

 

[Digital_Thor]

Have you looked at FaitalPro? They've got some nice coaxials. I've got a 8HX150 to play with, just haven't had the time.

You just have to wonder whether the given response is flush mounted or what? Because it only shows one on axis and beamwidth.
Further, it has an annoying shape to fit in a "hole"
https://faitalpro.com/en/products/Coaxial_Loudspeakers/product_details/index.php?id=351030100

 

[PGansz]

I have only a little. They just don't provide much data on their products and I won't buy something without it. I have a hard enough time with SB bc they don't give xmax data. It just doesn't make sense.

 

[Devnull]

You just have to wonder whether the given response is flush mounted or what? Because it only shows one on axis and beamwidth.
Further, it has an annoying shape to fit in a "hole"
https://faitalpro.com/en/products/Coaxial_Loudspeakers/product_details/index.php?id=351030100

It really wasn't that bad to make the hole. That's an 8PR200 sunk below flush with a round over. Hard part was getting the depths set to allow for the tweeter flange to overlap the midwoofer.

 

[Digital_Thor]

It really wasn't that bad to make the hole.

Oh yeah, it can be done. Usually they mount from the inside of the cabinet or use a cover/flange to hide screws a make the driver flush with a slight camfer.
Pro drivers also tend to aim at an audience that is much more forgiving towards little errors, in contrast to typical HIFI or studio monitors.
Actually KEF needs to have their shadow flare/flange quite snug and flush, to have the smoothest response.

 

[Waxx]

The caox drivers used in speakers like Kef and Genelec are not for sale, and that quality in coax drivers in general is not avalleble for the general (diy) public. I don't know who makes the KEF drivers, but the Genelec coax'es are OEM made by PHL (France), but using seas tweeters. PHL does sell some Coax drivers themselves trough THPL (French distributor) but off course not the model (or even the tech) they use for Genelec, who is one of their main OEM customers.

From what i hear (I don't use coax cone drivers myself) SB and Radian makes the best coax availeble for the diy market right now. PHL is not so known in the diy market their so it can be that they are not regarded by many diy'ers altough. I would more lean towards coax compression drivers (like the B&C DCX464) in a MEH today, not cone coax drivers as like that you avoid a lot of the issues those have. But for those you need a big wavguide or horn which may defeat your goal off course.

 

[3ll3d00d]

I still use a radian 5208, you can see measurements in https://www.avsforum.com/threads/su...2104738/page-2?post_id=38398305#post-38398305 , it's similarly rough but tbh it sounds fine once you get the xo right (I recall going too low sounded really bad on certain female vocals)