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

[Raxumit]

Assembling and electronic work I am well acquainted with. However, I am new to from-scratch speaker builds. I do not have the facility or accommodations to do woodworking currently. Where would be the best place to get the panels cut?

I've cut a bunch of speakers completely myself, but baffles continue to be frustrating for me, so I eventually decided I would go CNC.

I approached a local maker space so I could use their CNC, but they had gotten rid of their CNC. But, they hooked me up with a local small manufacturer with a commercial grade CNC who has cut a number of baffles for me, and a few cabinets as well. I'm definitely NOT saving much money this way, if any, but I still do get the pride of my sloppy finishes.

 

[williamwally]

I wonder what the chances of getting Parts Express or Madisound to create a knock down kit for this speaker are?
How does that process work?

 

[617]

I wonder what the chances of getting Parts Express or Madisound to create a knock down kit for this speaker are?
How does that process work?

https://www.speakerhardware.com/ will probably make a kit. They've done 1 offs for me.

 

[Rick Sykora]

I wonder what the chances of getting Parts Express or Madisound to create a knock down kit for this speaker are?
How does that process work?

Madisound does not do and PE wants MOQs over 1000. If not speakerhardware.com, you can find local shops with small CNCs.

 

[bluefuzz]

Can I buy it as a ready-made loudspeaker?

I do not have the facility or accommodations to do woodworking currently

Seriously? Has everyone lost the use of their hands?

Any DIY/home improvement centre can cut plywood to size. Even without that there is nothing here that couldn't be acheived with a couple of cheap tools on the kitchen table. Have a little faith in your own ingenuity ...

 

[Inertiaman]

there is nothing here that couldn't be acheived with a couple of cheap tools on the kitchen table. Have a little faith in your own ingenuity ...

How exactly would you cut precisely-dimensioned, rabbet-edged holes using cheap tools on a kitchen table?

 

[Zaireeka]

How exactly would you cut precisely-dimensioned, rabbet-edged holes using cheap tools on a kitchen table?

With a newbinette of course!

Fabrication de ma newbinette

Afin de percer les emplacements de hauts-parleurs dans des caissons d'enceinte que je suis en train de réaliser je me suis confronté à un pr...

flolebricolo.blogspot.com

 

[bluefuzz]

How exactly would you cut precisely-dimensioned, rabbet-edged holes using cheap tools on a kitchen table?

Depends on how cheap you want to be.

You need to be able to drill two holes: one in the centre of the circle and one near the perimeter. That can be done with a simple hand-drill or brace - available at any flea market or home improvement shop's 'bargain bin'. Then you need to draw and cut a circle. A simple and accurate circle jig (AKA compass) can be made with an X-Acto knife blade through some scrap wood centred on the drill bit you used to drill the centre hole. Once the outer diameter is marked, the outer rabbet can be cut with same X-acto knife a little at a time then chiselled out. Again, a single cheap chisel, preferably a little wider than the rabbet can be had at any flea market or DIY emporium. Plywood has a built in 'depth gauge' so you know when to stop. The through-hole can then be cut with a compass saw or fretsaw. Clean up with sandpaper.

Obviously there are many other ways one could do this depending on the tools you do or don't have. Use your imagination ...

And before you say this is unrealistic, I made a pair of speakers as a teenager using pretty much the above method. They turned out fine and I used them for many years.

 

[moonlight rainbow dream]

For the DIY first-timers, consider buying and assembling the Parts Express C-note kit and use Xmechanik's mechano22 crossover. Add a simple crossbrace and some damping to the cabinet while you're at it. I think you'd end up with a similarly impressive resulting project.

 

[letspla13]

Seriously? Has everyone lost the use of their hands?

Any DIY/home improvement centre can cut plywood to size. Even without that there is nothing here that couldn't be acheived with a couple of cheap tools on the kitchen table. Have a little faith in your own ingenuity ...

You place far too much faith in home improvement centers . IF they have anyone who can unlock the saw , and IF they can find a tape measure , typically they will say they can only make cuts to within 1/8" accuracy , which when I've witnessed it that is more like 1/2" accuracy .
I also know someone who has had to go to the emergency room 3 different times for almost cutting off part of a finger chopping vegetables . There are people who should not use sharp or pointy things , so building cabinets should be left to others for them .

 

[Maiky76]

...or use a PR and there will be no port resonance, SBAcoustics for example offers PRs with twice the Sd of the woofer - but this increases the price...

I could not find a viable solution with the SB PRs (their fs are too low).
However I think I found ways that could work out for those who already built the speaker with minimal change.

@XMechanik, please correct me if I am wrong but the 8L specified seems to be the internal volume of the cabinet without removing the volume occupied by the Driver/Port/Xover. A rough estimation tells me that about 0.6L should be removed

#1 idea is to

1. use two Monacor ports extended to their maximum length (210mm)
2. double the thickness of the front panel (glue another 18mm baffle on the existing one), it can also help with the vibrations of the cabinet.
It is critical to significantly increase the diameter driver hole in the existing from baffle to avoid resonances
The volume added this way should be partially to compensating for the added port.
The internal box depth of the cabinet is 227mm and the front baffle is 18mm thick, with a port 210mm long this only provides (227-210+18 =) 35mm clearance from the wall.
This is not enough, but by doubling the front baffle thickness we get (35+18 = ) 53mm which is still a bit short but better.
3. optional, chamfer or round over the now 36mm thick baffle to maybe decrease the the diffraction of the cabinet (smoother response)

The ports are not fully meeting the targets but close enough and should provide ample headroom at anything but the maximum SPL capabilities of the driver...

#2 idea is to

1. use one MBR-50 Monacor port extended to 224mm (MBR-50, internal diameter 51mm, length 150 to 280 mm, Sv=20,4 cm2)
2. double the thickness of the front panel (glue another 18mm baffle on the existing one), it can also help with the vibrations of the cabinet.
It is critical to significantly increase the diameter driver hole in the existing from baffle to avoid resonances
The volume added this way should be partially to compensating for the added port.
The internal box depth of the cabinet is 227mm and the front baffle is 18mm thick, with a port 224mm long this only provides (227-224+18 =) 21mm clearance from the wall.
This is not enough, but by doubling the front baffle thickness we get (21+18 = ) 39 mm which is still a bit short but better.
3. optional, chamfer or round over the now 36mm thick baffle to maybe decrease the the diffraction of the cabinet (smoother response)

The port is not fully meeting the targets but close enough and should provide ample headroom at anything but the maximum SPL capabilities of the driver...

If I were to start from scratch I would redraw the box to have indeed 8L net tuned to 51-53Hz but with a larger port that meets the 5% of speed of sound criterion even at max excursion.
The cabinet would have to be larger, the depth would definitely need adjusting to both accommodate the longer port and achieve the 8L target.
Height (increased towards the "bottom") could also be adjusted if required be adjusted with minimal impact on the response.
The port surface area is the minimal viable value to meet the 5% of speed of sound criterion that would need to be adjusted to the nearest standard PVC pipe and the length recalculated.

Or alternatively use the same MBR-50 port with 8L at +/-52Hz

Side note, it simple to understand with the execution simulations why I always add a high pass filters to my EQ to prevent bottoming the driver at high SPL... Q.E.D.

 

[Inertiaman]

The internal box depth of the cabinet is 227mm and the front baffle is 18mm thick, with a port 224mm long this only provides (227-224+18 =) 21mm clearance from the wall.
This is not enough, but by doubling the front baffle thickness we get (21+18 = ) 39 mm which is still a bit short but better.

I'm not understanding how adding thickness to the front baffle will increase port-to-wall clearance?? If the port were placed on the front baffle, then added front thickness would shift the port away from the rear wall. But the port is on the rear, so adding thickness to the exterior of the front will do nothing for the interior clearance to the port tube edge, no??

Also, the limiting factor for port length with the current port position is the backside of the tweeter, not the backside of the front baffle. The tweeter extends 27mm past the interior of the front baffle. Adding baffle thickness would reduce that by 18mm to 9mm, but still "in the way".

If one were to start from scratch, and wasn't concerned with build complexity, then perhaps a front slot port below the mid/woofer, combined with increased cabinet depth, could provide sufficient cross-sectional area and length to achieve your port objectives? (interior panels create a "tube" across the bottom and partially up the rear).

 

[Gringoaudio1]

I'm not understanding how adding thickness to the front baffle will increase port-to-wall clearance?? If the port were placed on the front baffle, then added front thickness would shift the port away from the rear wall. But the port is on the rear, so adding thickness to the exterior of the front will do nothing for the interior clearance to the port tube edge, no??

Also, the limiting factor for port length with the current port position is the backside of the tweeter, not the backside of the front baffle. The tweeter extends 27mm past the interior of the front baffle. Adding baffle thickness would reduce that by 18mm to 9mm, but still "in the way".

If one were to start from scratch, and wasn't concerned with build complexity, then perhaps a front slot port below the mid/woofer, combined with increased cabinet depth, could provide sufficient cross-sectional area and length to achieve your port objectives? (interior panels create a "tube" across the bottom and partially up the rear).

Agree. That made no sense. Language barrier perhaps?
If Port length is an issue maybe it could run vertically and exit on the bottom and the speaker sit on rails that space the bottom of the speaker off of whatever surface it sits on?
I added depth to the box for some bookshelves for scanspeak revelators by adding a compartment for the crossover at the back. The long port then ran through that compartment to the back wall. So the volume taken up by the port didn’t caculate into the volume of the box portion the woofer occupied. And the length issue was hidden from view.

 

[Maiky76]

Sorry brain fart!
I started last night writing about the minimal port area thinking, it's DIY, so people are free to adjust the dimensions…
Then this morning reading the comments about the difficulties to get the job done I though I should try to find something with a minimal amount of modifications.
I got distracted...

Still, the idea is to add one panel on the back not necessarily just 18mm, 22mm (or more) works too,
Then relocating the ports might work even if it means cutting a bit of the plastic flange.

This the front view but the ports are at the back, the two circles are 45mm in diameter
They would need to move towards the center line of the speaker by a small amount in real life.
The length is OK with the added thickness, by hollowing out a good portion of the existing back panel the volume stays about the same.

Someone would have to double check though as I have been known to make mistakes.

Anyways, I’d rather redo the box to have a better port and LF performance.

 

[mga2009]

Sorry brain fart!
I started last night writing about the minimal port area thinking, it's DIY, so people are free to adjust the dimensions…
Then this morning reading the comments about the difficulties to get the job done I though I should try to find something with a minimal amount of modifications.
I got distracted...

Still, the idea is to add one panel on the back not necessarily just 18mm, 22mm (or more) works too,
Then relocating the ports might work even if it means cutting a bit of the plastic flange.

This the front view but the ports are at the back, the two circles are 45mm in diameter
They would need to move towards the center line of the speaker by a small amount in real life.
The length is OK with the added thickness, by hollowing out a good portion of the existing back panel the volume stays about the same.

Someone would have to double check though as I have been known to make mistakes.


View attachment 367348

Anyways, I’d rather redo the box to have a better port and LF performance.

What about a sealed alignment and use a small SW??

 

[Hifihedgehog]

https://www.speakerhardware.com/ will probably make a kit. They've done 1 offs for me.

Who'd be interested in a group buy to get the price down? I'd love me some quality cabinets from them!

 

[Fred H]

I'm interested.

 

[S=klogW]

What about a sealed alignment and use a small SW??

I love the rich seam of possibilities Mechano23 offers. Many thanks to @XMechanik for generously sharing his knowledge and experience with us all. I am a total novice when it comes to loudspeaker design but I've really be fired by this project. I too would like to pair Mechano23, but my preference is with separate left and right sub-woofer cabinets handling the 35Hz to 80Hz and with one Mechano23 sitting on top of each sub - essentially making a pair of three-way speakers. I found a site that calculates whether your speaker should be in a sealed or ported enclosure and this SB Acoustics 5″ SB13PFCR25-4 Paper driver, with its Fs=44Hz and Qes=0.33 (for reasons I don't yet understand) is calculated to be firmly in the ported camp. I don't know though, if this result is saying that a sealed enclosure is a no-go for the SB driver or that sealed is still viable, just not optimum in terms of getting the best from the driver when it isn't augmented by subs.

https://www.diyaudioandvideo.com/Calculator/SealedVsPortedSpeakerBox/

 

[S=klogW]

Sorry brain fart!
I started last night writing about the minimal port area thinking, it's DIY, so people are free to adjust the dimensions…
Then this morning reading the comments about the difficulties to get the job done I though I should try to find something with a minimal amount of modifications.
I got distracted...

Still, the idea is to add one panel on the back not necessarily just 18mm, 22mm (or more) works too,
Then relocating the ports might work even if it means cutting a bit of the plastic flange.

This the front view but the ports are at the back, the two circles are 45mm in diameter
They would need to move towards the center line of the speaker by a small amount in real life.
The length is OK with the added thickness, by hollowing out a good portion of the existing back panel the volume stays about the same.

Someone would have to double check though as I have been known to make mistakes.


View attachment 367348

Anyways, I’d rather redo the box to have a better port and LF performance.

Hi, @Maiky76 I find myself wondering whether for certain the great god of Acoustics long ago decreed that all bass-reflex ports absolutely have to run in straight lines. If the exit holes for the two Monacor MBR-35 tubes you are cleverly proposing were instead to both be located low on the back baffle and then two of these* were surgically inserted into them (using hacksaw; pvc pipe weld glue) wouldn't the extra freedom of a diagonal route mean the clash with the drivers could be avoided?

these* = https://www.screwfix.com/p/floplast-push-fit-obtuse-bend-white-135-45-40mm/17596

 

[G|force]

Hi, @Maiky76 I find myself wondering whether for certain the great god of Acoustics long ago decreed that all bass-reflex ports absolutely have to run in straight lines. If the exit holes for the two Monacor MBR-35 tubes you are cleverly proposing were instead to both be located low on the back baffle and then two of these* were surgically inserted into them (using hacksaw; pvc pipe weld glue) wouldn't the extra freedom of a diagonal route mean the clash with the drivers could be avoided?

these* = https://www.screwfix.com/p/floplast-push-fit-obtuse-bend-white-135-45-40mm/17596

There was at least one vintage Pioneer speaker that used a cardboard port with a 45 degree bend in it.