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Small 2-way speakers with linear on-axis and power response characteristics (Scan Speak and SB Acoustics drivers). H&V off-axis measurements included

wineds said:
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Small 2-way speakers with linear on-axis and power response characteristics (Scan Speak and SB Acoustics drivers). H&V off-axis measurements included

Okay, finally got all my parts in. Would appreciate it if anyone could verify my crossover wiring. Arrows just indicate left or right wire of each component . Thanks in advance! The wiring looks ok, except the place marked with question mark. It seems that tweeter coil (0.39mH) is shorted an...
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Click to expand...
thank you for the PCB
 
Ossian said:
Thanks! Many good tips here, some of it I don't fully understand but I will read again and try to understand and ask if I have any question.
Click to expand...
One more tip.
I've printed the router baseplate on my custom needs, it is really cheap method. You just need to screw a countersunk head screw and use it as a centre.
 

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onmumucm said:
One more tip.
I've printed the router baseplate on my custom needs, it is really cheap method. You just need to screw a countersunk head screw and use it as a centre.
Click to expand...
Sorry I don't understand, do you mean according to your custom needs or is 'custom needs' some kind of machine (3d printer?)? Looks like the red part is made on a 3d printer but the yellow part I'm not sure. English is not my native language.

Do you mean the countersunk screw which is not attached in your picture? Is this baseplate able to cut variable diameter circles by itself or would it need a round cutting jig attached? Thanks for the help!
 
Ossian said:
Sorry I don't understand, do you mean according to your custom needs or is 'custom needs' some kind of machine (3d printer?)? Looks like the red part is made on a 3d printer but the yellow part I'm not sure. English is not my native language.

Do you mean the countersunk screw which is not attached in your picture? Is this baseplate able to cut variable diameter circles by itself or would it need a round cutting jig attached? Thanks for the help!
Click to expand...
Both parts are made on 3d printer, here is a photo to explain what exactly I mean how to use screw as a center to cut. The position on photo is for making a hole Ф78mm.

1735648856713.jpg
English is not my native language too.

Also finally, I finished my speakers, as my DIY hybrid amp too. I applied very old and thick veneer on speakers. Decorative speaker terminals holders is made of steel on laser cut CNC and powder painted. Bass-reflex tubes were made on 3d printer. (sorry for dust on speakers and amp)

1735550512280.jpg
 
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I could use a little bit of help from the members.

I am using 3/4 inch mdf 19.05mm for the build.

Assuming 8L, I believe I would have to change the total box depth to 271.5mm. I would keep the height and width the same. This assumes the port and drivers take up no volume.

I cannot get the monacor ports in my area I settled for https://www.solen.ca/en/products/solen-pt-2ex-50mm-adjustable-length-port-tube Speaker Cabinet Adjustable Port Tube 50mm x 160~280mm L (2"x6~11"). So this would be similar to the monacor 50. Internal diameter is 50 mm vs 51 mm. The initial port thickness is 2mm, and the part that goes on to extend length is 2.61mm wide.

When I crunch some numbers factoring in the port area for 53hz tuning. The box jumps up to 284.6mm in total depth. The Port seems only to need a 213mm length. Sub box pro/vs winISD

1735844636324.png

1735844687474.png


WinIsd does not factor in the area the port takes up, correct? Or does it?

A quick workaround I am using is a sub-box pro
https://subbox.pro/en/

1735844926005.png


1735844963763.png





I cut up MDF sheet for 10 speakers total using the original dimensions. I then re-read the thread and relized the port is small for its size. I was going to buy two smaller monacor ports, but they were sold out. I figured going with the bigger port allows me to save some time and hassle vs two.

Now im stuck with a lot of MDF, and the mbr 50 equivalent port. But no idea what to set the port length to because I'm not exactly sure how each software calculates it.

TLDR: What is the length of the port when using the MBR 50 without having to double or triple the rear panel to get the optimal tuning?
 
HighFutility said:
WinIsd does not factor in the area the port takes up, correct? Or does it?
Click to expand...
No it does not, it's a very basic calculation there.

But I would mostly not stress out about the tuning here; even if you end up tuning it to 63Hz instead of 53Hz it's still perfectly acceptable. In fact, there's an argument for somewhat higher tunings to address the drop between 100-200Hz in the original design as measured by Amir.

For the parameters you gave (50mm ID of port, 8l net internal volume) 53Hz works out to 224.8mm and 63Hz to 148mm. So anything in between is good. But one reason to keep on the longer side is that if you over-estimated the net volume available, you will get a higher tuning frequency than expected. So I'd say just make sure there's 50mm of space between the end of the port and any walls/tweeter and then do as long as feasible. I would not really recommend stacking MDF panels just to get a longer port.

As for the surplus MDF - might as well make some bracing for the box to keep the resonances down.
 
Probably stupid question. Is there any benefit customize them with passive radiator like this one link ?
 
See the PR-discussion, I selected the SB15SFCR and made some measurements


www.audiosciencereview.com

Mechano23 Open-source DIY Speaker Review

Congratulations to Jarek/ @XMechanik for this excellent work. IMO this is a benchmark in price/performance ratio! And many thanks to Amir for testing this device and taking this contribution to the ASR front page. I think, this is a wonderful opportunity to give DIY-people a constructive...
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the relevant post:

www.audiosciencereview.com

Mechano23 Open-source DIY Speaker Review

Congratulations to Jarek/ @XMechanik for this excellent work. IMO this is a benchmark in price/performance ratio! And many thanks to Amir for testing this device and taking this contribution to the ASR front page. I think, this is a wonderful opportunity to give DIY-people a constructive...
www.audiosciencereview.com www.audiosciencereview.com
 
Pardon my ignorance.

What is the rationale behind having the rear port not aligned with the tweeter>? This is more of an OCD thing for me. Is it okay if I mount my port at the 66mm mark instead of 55?

1735959713141.png
 
HighFutility said:
Pardon my ignorance.

What is the rationale behind having the rear port not aligned with the tweeter>? This is more of an OCD thing for me. Is it okay if I mount my port at the 66mm mark instead of 55?

View attachment 418473
Click to expand...

Designer specifies no polyfil in port area. So if you move it then you would alter the polyfil coverage. Also if you adhere to the design as is you can be confident that it measures as per Amir's results.
 
HighFutility said:
I could use a little bit of help from the members.

I am using 3/4 inch mdf 19.05mm for the build.

Assuming 8L, I believe I would have to change the total box depth to 271.5mm. I would keep the height and width the same. This assumes the port and drivers take up no volume.

I cannot get the monacor ports in my area I settled for https://www.solen.ca/en/products/solen-pt-2ex-50mm-adjustable-length-port-tube Speaker Cabinet Adjustable Port Tube 50mm x 160~280mm L (2"x6~11"). So this would be similar to the monacor 50. Internal diameter is 50 mm vs 51 mm. The initial port thickness is 2mm, and the part that goes on to extend length is 2.61mm wide.

When I crunch some numbers factoring in the port area for 53hz tuning. The box jumps up to 284.6mm in total depth. The Port seems only to need a 213mm length. Sub box pro/vs winISD

View attachment 418158
View attachment 418159

WinIsd does not factor in the area the port takes up, correct? Or does it?

A quick workaround I am using is a sub-box pro
https://subbox.pro/en/

View attachment 418163

View attachment 418164




I cut up MDF sheet for 10 speakers total using the original dimensions. I then re-read the thread and relized the port is small for its size. I was going to buy two smaller monacor ports, but they were sold out. I figured going with the bigger port allows me to save some time and hassle vs two.

Now im stuck with a lot of MDF, and the mbr 50 equivalent port. But no idea what to set the port length to because I'm not exactly sure how each software calculates it.

TLDR: What is the length of the port when using the MBR 50 without having to double or triple the rear panel to get the optimal tuning?
Click to expand...
Did you already buy the 50mm ports? Else you have the option to go slightly smaller like 40mm PVC and cut it to length. Or get the passive radiator like @Chris*42 mentioned. Port volume and magnet volume should be substracted from the box volume to get the net volume of the box.
 
BossBunos said:
Did you already buy the 50mm ports? Else you have the option to go slightly smaller like 40mm PVC and cut it to length. Or get the passive radiator like @Chris*42 mentioned. Port volume and magnet volume should be substracted from the box volume to get the net volume of the box.
Click to expand...
I already bought the ports, but after running simulations in Winisd, I think it was the right decision. The stock configuration's port velocity quickly exceeds 34m/s. Adding two ports would be the ideal solution, or running a single bigger port.

The 8L volume of the cabinets doesn't factor in the port, X-over, or drivers. If you add bracing down the middle, it shrinks it even more. Since I built my cabinet out of 3/4 MDF and kept the same dimensions, I'm already working with 7.71L before adding the aforementioned. Most likely, I'm going to tune the box to ~60hz plus, which is okay with me given I'm running multiple subs.

My final spec will have a 7.38L volume left over, factoring in a 177 mm-long port and 50mm internal diameter. This still doesn't include the tweeter, which protrudes into the cabinet space, bracing, or x-over.

Below is the original design, with a port length of 150mm tuned to 45hz and input power of 20W. The port is already at 30 m/s. I ran the other suggested options of running 2 Monacor 35 ports with a slightly higher turning due to the volume of space the ports take, and it seems the way to go if you want to run the speakers at a higher SPL and keep port velocity down.

Dislcaimer: I am a total noob.


EDIT: is the x max of the driver 4.5 or 5 mm?
1736182767253.png
 
XMechanik said:
'Linear coil travel (p-p) 9 mm' (link) so Xmax is 4.5mm
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Thank you for your prompt reply. As I am a newcomer to audio, there may be errors in my calculations. I am trying to absorb and learn as much as possible from experts like yourself.
 
Talking about ports, while working on a previous build, i had to use a lot of glue/sealant (hybrifix super7) and ended up with very sturdy 20cm long, 45mm inside diameter tubes.
tube.jpg
isd.jpg

Perfect for 50Hz tuning of Mechano23 8L box and using a nose to tail approach :)
The only question left is, is it ok for the port to end about 4.5 from the front panel and moved to where in would not interfere the drivers?
port-l.jpg
 
rokr said:
Talking about ports, while working on a previous build, i had to use a lot of glue/sealant (hybrifix super7) and ended up with very sturdy 20cm long, 45mm inside diameter tubes.
View attachment 419842 View attachment 419845
Perfect for 50Hz tuning of Mechano23 8L box and using a nose to tail approach :)
The only question left is, is it ok for the port to end about 4.5 from the front panel and moved to where in would not interfere the drivers?
View attachment 419847
Click to expand...
I like the resourcefulness and re-use!

As drawn, the tube is in the same space as the side panel thickness, so that exact location isn't viable. But generally speaking, I don't see any problems with having the port off-center.

Maybe consider placing it centered horizontally left/right, and vertically just above the woofer magnet? Although the top ~ 1/3 of the port would then "overlap" the back of the tweeter, even that overlap portion would still clear the tweeter magnet by 18mm. Seems like such partial "blockage" wouldn't meaningfully inhibit air flow to the port.

EDIT: looking more closely at the driver dimensions, there is > 55mm distance between the woofer magnet and tweeter magnet. So the port would fit there, and have pretty good clearance to the front panel, but overlap a bit of the woofer chassis.

Maybe the best option is centered between the driver magnets vertically, and then offset only ~ 3cm left or right? That should provide ample clearance to the side panel (and any damping material there), as well as both driver chassis.
 
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