Small active 3-way floor stander with a punch

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Hello everyone!

FIRST OF ALL:
As some of you know I was originally planning on building a 3-way ScanSpeak, (mostly) Revelator active floor stander. This is the thread regarding that design:
https://www.diyaudio.com/forums/multi-way/322048-18w-12m-r3004-active-3-a.html

Long story short - that plan turned out to be destined to fail.
Some of you also stated in that thread that it wouldn’t be good use of the 18W’s. I am glad you did because it made me do thorough testing which I otherwise wouldn’t have done. So, thanks to all of you who helped with that design, sorry it didn’t go anywhere. I hope you guys will also help me with this new design. I have learned a lot from what you said in the old thread and this is what the new design is based on.


I am still gunning for a small 3-way floor stander in the sub-30L size. I am still using the new Hypex FA123 to make them active. I have now used one of these modules for the testing done on the previous design and they are amazing!. I really like them.
I am still using my ScanSpeak R3004/662000 tweeters. To my ears they sound awesome and I was surprised how they measured in my old cabinets which aren’t exactly well designed with regards to diffraction – maybe I was lucky.
I decided to start all over with the remaining drivers to be able to choose ones that are better suited for my needs here and now. This sadly means selling my 18W’s -all 4, and my two new 12M (which btw. also sound very good to my ears!).
A lot of you guys recommended the SATORI line from SB’acoustics. (some used price as an argument I don’t see why, the price of a 18W is roughly the same as a 7” SATORI). I never heard these drivers, but considering where they are coming from and all the warm words, I have decided to try them (they are also much less demanding with regards to cabinet size. So far I am going for the SATORI MW19P-4. Now I will be using it as my lower midrange/upper bass driver. My simulations show that the 4 Ohm will be happy (Qtc of 0,620) in 13,4L. In such a sealed cabinet they should have a natural roll off with a F3 between 80 and 90Hz. The 8 ohm version would be able to go a little deeper, but would have a Qtc of 0,71. Not exactly sure which would be better for this build.
I have read that my tweeter should be able to perform well to 1700Hz, covering most of the area we are most sensitive too. This means that the larger driver will not harm midrange dispersion.
Then I have also learned that there is no substitute for membrane area in the deep. Soo I have decided to go hunting for a 10” dedicated Subwoofer driver to handle the lowest frequencies. The 10” means that the driver will have to be side mounted. As far as I have read this means, I should cross to this woofer at 80Hz or below. This suits well with the natural roll off of the 7” SATORI. So I guess this design will mostly be a small 2-way with a build in Subwoofer. I have been looking at a couple of different 10” drivers, mostly:
Vifa NE265W – 4 and 8 ohm version
SB-Acoustic SW26DBAC76 – Both 4, 8 ohm and dual voice coil verison.

So far I have chosen the NE265W in the 4 ohm version. This driver should achieve a Qtc of 0,713 in only 15,7L !! :O It also have a sensitivity and power handling better suited for my FA123 than the SB driver. At 100W one of these Vifa drivers should deliver 95dB (1m) at 30 HZ! And if I compare with the single 18W I made some tests with then this driver has a little more than twice the membrane area and 40% more travel at 100W. The numbers say it will perform better than 2 18W in less volume than one 18W would need!. I am very excited over this driver! …. At least it’s numbers.

My new design can be seen on the first four pictures.
Another new thing is that the design is actually just a 2-Way active bookshelf with an extra Sub output, which is then stacked on top of a passive Subwoofer. The fifth picture show what the 2-Way would look like alone (with a different front and rear plate and side covers of course). The sixth picture show what the Subwoofer would look like without the 2-Way on top.

This will give me some flexibility for the future. I can rebuild the Sub without having to redo the whole thing and Vice-Versa.
 

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First Questions

So of course, I have some questions!

Does anyone have experience with using the 7” SATORI in a sealed 13-14L cabinet down to 80Hz? Would you go with the 4 ohm for a Qtc of 0,62 or the 8 ohm for a Qtc of 0,71.

Would my design with the aperiodic vent work? The channel has the same cross section as the vent itself, and with no damping material it shouldn’t obstruct the frequencies let through by the vent, or? Would it have some kind of port effect? The image is trying to ilustrate the intended airflow.

Does anyone know the Vifa NE265W-04? Have anyone used it in a sealed subwoofer? I have read that Michael Chua (a member in here) have build a subwoofer with this driver back in 2011. He seemed very happy with it, but he didn’t give much details on it. Remember I will be using my DSP to boost it in the low frequencies That is why I can go sealed.

Are there any other 10” driver out there that would be even better for a small 16l sealed sub? Or will I get better results with a smaller 8”?




And as always, general design inputs are always welcome! Even though I tried to incorporate as much as possible of what you told me in the old thread.
 

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Hi Danner

Interesting thread. I have read through your previous one too.

I am on a very similar path (Smallish 3 way, sealed) except that I have mentally invested in a minidsp MiniShark approach.

My drivers are all Revelators:
R29-7000
15M4531
22W8861

I am beginning to think of a different approach and am likely to sell the off some of the drivers before I start, so that I can build something slightly smaller and more stylish. Am thinking MTWW, using
15M4531
602010 small frame tweeter
15W4531
15W4531
 
Hi Dublin,

Also sounds like an interesting and compact build with the 3 revelators! INteresting to see how they can perform!
The 22W still needs above some 25L won't it?


Hi Bushmeister,

HAHAHA! I love the name of your speakers!
Ceritanly also an interesting build! Cool use of ikea products :p
Okay good to hear you like the SATORI driver! I just skimmed your build thread, will read it closer tomorrow! But it ceritanly is also some mean subs you build there! Sad i dont have the power and room for those woofers, they look mean! I would also love to have to push push woofers, but don't know of any suitable 8" woofers where two would fit in sub 20L.. :/

Do you think it will be directly bad with one side mounted 10" driver? It is not the heaviest driver membrane.
 
Hi Danner

Interesting thread. I have read through your previous one too.

I am on a very similar path (Smallish 3 way, sealed) except that I have mentally invested in a minidsp MiniShark approach.

My drivers are all Revelators:
R29-7000
15M4531
22W8861

I am beginning to think of a different approach and am likely to sell the off some of the drivers before I start, so that I can build something slightly smaller and more stylish. Am thinking MTWW, using
15M4531
602010 small frame tweeter
15W4531
15W4531

Very nice. Salad bowls.

Having a peak at the build link now.
 
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Hi Danner, for music a single 10" woofer/sub should be fine as long as it has reasonable x max. Also as long as your cabinets are solidly constructed and heavy, dual opposed is not essential - but it sure is nice!

My subs are overkill for most stuff, but with some music and most movies they really shine!
 
Bushmeister# Okay, good to hear. I know i am not building the perfect speaker, but i am hoping that i am building the best speaker for my situation.. Would you think a side mounted 10" is better or worse than a side mounted 7" in both sides(push push)? The surface area will be rougly the same, but x-maks won't and BL wont.

Is there a thing as overkill in speakers? :p Isn't it always ideal to have as much headroom as possible ? :)
 
Hi Danner - that really depends on the drivers!
I will say the the dual opposed configuration completely cancels all driver induced vibrations from passing into the speaker cabinet.

This is particularly important if you are putting the subs into the same enclosure as the mid and tweeter. You want to minimize cabinet coloration as much as possible.

The 10" subs I used - alpine SWR 10D2- can be used in as little as 11 litres per driver. So if you have 20 litres to play with you are almost there sealed. They also have 20mm X-max, with 70mm X-mech - so really decent displacement and safety margins!

I would recommend DSP for the low end - but I think DSP is essential for decent sub performance - the ability to manage in room response from listening position average measurements for <100hz is one of the best uses of DSP in my opinion. Unless you have an amazingly treated room, and can place your subs in the ideal position (both of which is unlikely) or you have 4+ subs (also usually unlikely), DSP is a fantastic tool.

Of course it has to be used properly - cut peaks, do not boost dips, use averages for the whole listening area - not single point measurements, and follow trends rather than chasing down absolutely flat in room responses.
 
Yeah i know the dual driver is the ideal, it was also my initial thought. I did look at those subs, they truly look mean, but they also require a lot of power and room inside the cabinet don't they?
I am very limited in size though. My cabinet is only 250mm wide on the widest spot, The subs have to be slightly submerged from that point not to stick out anywhere. So the largest drivers i can put back to back will be 7".
If i put one driver higher than the other, i may be able to have 8" or 10" but this wont be ideal either, right?

I am definitely going to use DSP. My speakers will be 100% digital with the FA123. All crossovers will be DSP controlled, no analog crossovers.
Thanks for the tips on room correction!
 
Hello bushmeister,

I have briefly been looking at that driver as well, but my simulations in winisd yielded 14L pr driver(Unibox says 10 can do with heavy stuffing).
Do you have any experience with this driver yourself? Or Dayton in general?
I haven't looked further at it because I thought it wasn't a "HiFi" subwoofer. Are those flat subwoofers capable of delivering decent sound quality and not just boom?
 
Thank you for the link!

There is either something wrong with their specs or i am unable to do simulations.. He is writing that 12,7L gives a Qtc of 0,7 wheras my sim say 19L. But if it is true that they only need 12,7L then it may be a good solution.
I am planning on cutting them at 80 Hz.
 
Okay so i have been looking on subwoofer drivers again. Considering your advice on back to back woofers I think i ditched the Vifa and is back with flat drivers. However, I have compared the Dayton to my original SB choice and I think I will be going with the SB driver:
"SW26DBAC76-3-DV"

I somehow trust it more, and the simulations are better. Two of these SB'drivers will fit in 20L with Qtc of 0,685 whereas two daytons would have a Qtc of 0,852 in 20L.
I laso talked to Hypex on how much power the amps can deliver at different ohm loads as this was important for mi choice of the Dual Voice coil version of the SB woofer. Two SB woofers should deliver 97dB @ 30Hz and the two Daytons will deliver 93dB @ 30Hz.

I will start out by buying two of the SB drivers, one for each speaker and the possibility to test the benefit of having two drivers in one cabinet. If I can hear it is worth it then I will buy two more. The cabinets will be designed for two drivers mounted back to back.
Also the cabinet design will change again.. I will just make it as one combined unit, this will allow me to move the Amp down to the bottom of the speaker, simpler design and more volume for the Sub's.
 
It would be best to physically join the backs of the subs - with a brace or something- this is what allows the force cancelling to work.

In my subs the enclosure is a cylinder so the frame of each driver is directly connected to the other by the cylinder, but I also had threaded tensioning rods too. This results in a solid driver-driver coupling and complete force cancellation as a result.
 
Hmm.. I reconsiddered my bracing and I just changed the design of the bracing structure slightly. Now i think my cabinet and barcing will act almost like your cylinder cabinet.
Since my woofers are sliightly off angle i cannot use threaded rods through them, but i am convinced that this design will give a pretty solid woofer to woofer connection.

The red lines on the first image show how the woofers are connected top and bottom. The second image shows where the connections are - also the front and rea plate connect the woofers.

This is a square "cylinder" with holes.. Of-course not as strong as a full cylinder, but i am sure it is strong enough!
 

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Hi Danner, for music a single 10" woofer/sub should be fine as long as it has reasonable x max. Also as long as your cabinets are solidly constructed and heavy, dual opposed is not essential - but it sure is nice!

My subs are overkill for most stuff, but with some music and most movies they really shine!

I just yesterday started playing with my "sub". I am using a single "9 inch" SB model SB23MFCL45-4 4 Ohm subwoofer driver with a Hypex DS 2.0 plate amplifier. Currently, I am trying this in a closed box about 0.85 ft.^3 (24 L). I have some more work to do yet but I think this small, closed box will be plenty good enough for my smallish listening room. NOTE: My amplifier sub-out jack is at a fairly low level; the Hypex wasn't getting loud enough (175 Watts into 4 Ohms is plenty of power!) so I had to add an in-expensive (15 dB gain max with a variable/level control) pre-amp between the sub-out jack and the Hypex low level inputs. MUCH better; now I am getting full output! I listened to some pipe organ music and also used some free test tones; I have plenty of SPL down as low as 16 Hz! The nice thing about this Hypex is that it has an infra-sonic filter FIXED at 12 Hz. If you have a small to medium small room, this is a good combination, not too expensive or large. The SB sounds great; realistic, not like those cheap big box store HT subs that are just glorified boom boxes! Cheers! (PS, my Hypex model is now apparently discontinued!)
 
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