SB acoustics Sasandu speaker build

[davewantsmoore]

double post.

Edited February 4, 2024 by davewantsmoore

[playdough]

Hi

If you put up the  Electro mechanical parameters of the drivers, volume of enclosure and the port dimensions I can have a crack at running WIN ISD and generate a few graphs.

 

[JD1]

Guys thanks for the posts. I have been busy. Dave thanks for that correction. I was going round in circles trying to figure which way is right. I think I have it figured out now. Gene I don't know if I have that data but will have a look. I think if all else stays the same but the diameter I just have to tweak the length. Am going to contact Wagners to see if they sell the port.

[BioBrian]

21 hours ago, davewantsmoore said:

If you lengthen the port (which you will need to do to compensate for the reduced diameter, to keep the volume the same)

 

Dave, I think this needs editing too. A longer port will need to be a larger diameter, to be tuned to the same resonant frequency.

 

In the case of this build, going down from 75 to 68 mm diameter would need recalculation in WinISD, and would result in a shorter port.

[BioBrian]

I found the TSPs from the driver datasheet, but wonder if other info on this design is for public knowledge, like as @playdough has suggested, box volume, vent size, etc.

[BioBrian]

BAAH! I got all excited about WinISD, but having recently "upgraded" to a 4k monitor, the text in WinISD is so tiny, I can't read it. Another one in my ever-expanding too-hard basket. (Fix, anyone, please?)

[JD1]

I could do a calc on the box size if this will help. I am at the stage though where I think that the ratio of the areas multiplied by the length of the original tube may be close enough. If you can calc it on WinISD easy I can easily get the volume. I am an ex surveyor so volumes and areas are not hard. Thanks for the input. 

[BioBrian]

37 minutes ago, JD1 said:

I am an ex surveyor

 

Good luck getting your tripod inside those woofer holes, haha... Yes, the volume of just the woofer compartment would make the effort worth-while, and should be easy.

 

It's a bit of a performance getting WinISD to cooperate - it's quite frustrating for wannabe speaker designers like me. If you feel inspired to have another go, delete the file you started, and try entering the TSPs in this order:

 

Mms, Cms, Rms, Xmax (it's 6.7, being half of P to P), Sd, Bl (7.5 Tm), Re, and Pe (70 W). Make sure you have the units exactly right, eg 1.52 mm/N for Cms. That should be enough for it to fill in the other fields.

 

Who knows, we might end up with half a dozen perfect designs here.

 

37 minutes ago, JD1 said:

I am at the stage though where I think that the ratio of the areas multiplied by the length of the original tube may be close

 

Not so sure. And you want to be sure, after all the great effort you've put in so far. Just one more little wafer...

Edited February 5, 2024 by BioBrian
forgot a few bits

[JD1]

Can set my tiny Tripod up inside and do and scan of the inside. Can get the volume but that is all. What sort of accuracy is needed here. There is Dacron inside which is probably not a factor. Port volume will not be included. I tried WinISD but it won't run in Apple. In saying that I probably would not be able to drive it.

[BioBrian]

Compared with the world of a theodolite, acoustics is a rather blunt instrument. To the nearest litre would be fine.

 

The Dacron does change the effective volume, but for now I think we ignore it, at this level of operation.

 

The vent dimensions would also be useful to some of us.

[JD1]

Box Volume = 163 litres. Original port was tapered 75 with a 100 mm diameter cutout hole and 100 mm long paper tube. This port is not available but comes only with the kit. The one I have is a 68 mm tapered tube with a 98 mm cutout. Hope this is enough info to calc what I need. From what I can see about 82 mm puts me in the ballpark.

[playdough]

Ok, so internal volume of the enclosure is, haven't seen anything else with regard to the small parameters of the driers @BioBrian may have ?

2 hours ago, JD1 said:

Box Volume = 163 litres

With regard to the port, my 10c worth of is to try make a tube to the exact dimensions, prescribed in the instructions, after all, that's the successful design and any change is a re design and needs to be simulated

I'm unsure if the port dimensions include a tapered tube ?

 

A suggestion is to make a plug out of pine or similar on a lathe, then lay up fibre glass to fabricate the tube/tapered tube, to the mm if possible. It would not be overly difficult, but does require a lathe of some sort and a little fiberglass work.

 

Would still like to run a model in Win ISD if I can get it running   I did use it a few months ago for an Acoustic Elegance TD18+ driver.

 

 

[playdough]

2 hours ago, JD1 said:

Box Volume = 163 litres. Original port was tapered 75 with a 100 mm diameter cutout hole and 100 mm long paper tube. This port is not available but comes only with the kit. The one I have is a 68 mm tapered tube with a 98 mm cutout. Hope this is enough info to calc what I need. From what I can see about 82 mm puts me in the ballpark.

 To be accurate to the actual design, would be preferable, however at some point the speaker would need to be measured. If this won't happen, it's probably better to go to a little trouble, for the outlay and time in building up this cool speaker set. 

Either way a small departure from design especially port volume and length, would need either need a simulation before or measurement for tuning after the build.

Yea, it's in the ball park, might be ok although it may not measure up exactly correctly. Probably would sound reasonable.

[BioBrian]

I found the Sasandu Drawings by Googling just that.

 

The driver datasheet can be downloaded easily too.

 

The box volume looks to me to be more like 63 litres, not 163. Would that be as typo, I wonder @TP1?

 

I tried to paste the TSPs here, but the format went nonsensical. Sorry, but with my aforementioned screen resolution problem, I'm unable to invest further into this at the moment.

 

I think with the vent problem, the best/easiest way to find out is to get someone to bring DATS (and a non-Mac computer) around and measure the impedance of the whole caboodle when finished. The vent needs to match the resonant frequency of the driver in-box, and I have no faith in modelling being the last word in decision-making in this case.

[JD1]

Sorry Brian I did the volume early this morning and rushed it and realised when I was out I had botched it. 70 litres. 

[afa]

According to the info of the kit here.
https://www.madisoundspeakerstore.com/3-way-speaker-kits/sb-acoustics-sasandu-kit
the vented volume is 50.5 litres
and 18.1 litres for the sealed volume
port tuning frequency is 32Hz
50.5 ltres vol, 32 Hz tuning, 68mm (straight) vent dia gives a length of about 150~168mm (dependent on end termination, ie. no flare, one flare,  flares both ends)
tapered vent tubes are hard to model, so you might have to try trial and error to get the 32 Hz tuning
If you are out a few Hz no big deal in the scheme of things, your room acoustics and location of speakers and listener will swamp a few Hz difference in tuning (which varies slightly anyway with temperature and air pressure changes, driver excursion etc.. along with port compression effects)

E&OE

Edited February 6, 2024 by afa
add text

[JD1]

Project is progressing steadily. Have the cabinets painted and will post a picture when I get them mounted on the bases. The crossovers are done. I have zip tied them better than the photo with at least two ties to each inductor and some glue on a couple. My soldering leaves a bit to be desired but connectivity seemed good. Will use terminals to connect to the drivers as not confident in my ability to solder the wires on., particularly the tweeter. The drivers are still on the way from Asia and about a month away. Slow boat from China. Looking forward to hearing the end result.

 

Cheers

Jon

Edited March 1, 2024 by JD1
Added photos

[Type 1]

Nice work!

A fair bit of complexity with the cross over!!

Nasty when stock won’t arrive on time….. that’s our world at the moment!

Good thing that you have patience!!!

[JD1]

Slightly further along the production line, cabinets with paint, on the base and crossovers finished.

[JD1]

Have speakers working and very happy. Sound awesome. At present have gold plated quick connect terminals on the drivers and the wire is silver plated so there is no corrosion. Is soldering a better option. I read so many differing opinions but it seems the biggest angst with terminals is the corrosion and danger of coming loose. Solder is a poorer conductor and probably less surface contact. Im not game to trust my soldering particularly on the tweeter so if I solder will have to pay someone which kind of wrecks the DIY feeling and claim.

 

These are the best sounding speakers I have heard not that I have heard a lot. The highs are beautiful mids clear and the bass is good. Hearing so much more in my music and can play music softer and still enjoy. I can't really give a good review as not experienced with a lot of other gear. Main thing is happy in the end. Making these things and and having them turn out a success is really a great feeling. Only about 10 hours on the clock so I think there is still room for improvement. Have to say thanks for the help I have received here. 

 

Cheers

Jon

Edited March 11, 2024 by JD1
Added photo

[Grimmie]

What a great result, they turned out looking beautiful well done @JD1. They every bit the equal of commercial speakers and I'm pleased you love the sound.

[JD1]

Thanks so much for that Grimme. I'm as pleased as with the result. The sound improvement is quite noticeable. Im hearing lots of little things in music I've listened to for years that I've never heard before.

[Type 1]

Hi Jon!

I was expecting Black, but that colour is a bit easier to get along with!!!

Just something that I’ve noticed… your speakers are in front of windows… sadly so are mine… I found some cheap 2nd hand acoustic panels on Facebook marketplace and I think that the sound is just a bit nicer!! ( panels behind the speakers)

Sadly you live too far away to drop in for a listen…..

Thanks John D

Ps… your soldering question is out of my league…. Sorry  

[JD1]

Hi John

I felt black was to hard to paint as it showed the flaws but when I did the bases they came up better so I may redo them, but the white does look good with the black cones.

I close the curtains which helps with sound reflections and hang a blanket ov the the TV as it interferes with the stereo imaging. I do intend to make some room treatment some time. Maybe next project. Or will it be home made subs and surround sound. I may have caught a bug.

[rhale64]

I just read this entire thread. Great work and great sounding speakers. I would know.