So, I want to build some small full range speakers and they need to be 8ohm. I found the Mark Audio CHN-40 so I ordered a pair. They have some box designs on the product page, and I like the "Compact Mass-Loaded Horn".
When Looking at the dimensions, it looks to me like it doesn't quite work with the driver being 40mm from the inside top. This would put the chamfer behind the driver cutout partly into the face to top joint. I decided to quickly draw up the box in Fusion360 and it confirmed my suspicions. I also think it looks a bit funny way up there.
If the design is anything like the BiB box, then I would also suspect the internal baffle should be 64mm from the top, and not 40mm, which might might be a better distance down. They have a similar design for the CHN-50 and this is the case.
Any ideas on this? is this a typo on their end? I'm a decent builder, but no designer by any means.
When Looking at the dimensions, it looks to me like it doesn't quite work with the driver being 40mm from the inside top. This would put the chamfer behind the driver cutout partly into the face to top joint. I decided to quickly draw up the box in Fusion360 and it confirmed my suspicions. I also think it looks a bit funny way up there.
If the design is anything like the BiB box, then I would also suspect the internal baffle should be 64mm from the top, and not 40mm, which might might be a better distance down. They have a similar design for the CHN-50 and this is the case.
Any ideas on this? is this a typo on their end? I'm a decent builder, but no designer by any means.
The sketch isn't (visually) to scale, just representative of the overall layout & to provide the dimensions.
Yes, I understand that, but my 3D design is to scale and it puts the chamfer on the speaker hole into another panel which seems wrong (and kind of defeats the purpose of the chamfer).
Also as far as I've seen in other designs, generally a folded horn doesn't shrink at the fold does it? (76-76-76 in the CHN-50 design)
Here is the same named design but for the CHN-50. In this design, the driver is placed 1/2 the depth - the thickness of the baffle down.
Also as far as I've seen in other designs, generally a folded horn doesn't shrink at the fold does it? (76-76-76 in the CHN-50 design)
Here is the same named design but for the CHN-50. In this design, the driver is placed 1/2 the depth - the thickness of the baffle down.
Scott,
Since the driver has a diameter of 78.4mm, a 40 mm distance from the inside of the top would put the driver right at edge, and looks like the OP has a concern with that, as it can lead to early reflections by placing the back of the cone so close to an internal surface.
Since the driver has a diameter of 78.4mm, a 40 mm distance from the inside of the top would put the driver right at edge, and looks like the OP has a concern with that, as it can lead to early reflections by placing the back of the cone so close to an internal surface.
As noted, the sketch is intended as a simple visual representation of the dimensions, no more. An internal chamfer is not necessary, although you can add some if desired. The baffle position is a functional part of the design (I know it appears asymmetric relative to the front-rear plane; this is deliberate). The two enclosures being compared above are individual designs rather than scaled variations of each other, so they have slightly different features, with different tap locations for the drivers & vents, a slightly different internal configuration, and different target alignments.
Last edited:
Thanks for the information and clarification everyone. I will build it with the internal dimensions as per the drawing.
Another question, if I choose to make the face taller so the driver is perceived to be lower from the top (purely for aesthetics), will this effect sound quality? I just find it "looks" so close to the edge of the top. I know this is subjective.
Another question, if I choose to make the face taller so the driver is perceived to be lower from the top (purely for aesthetics), will this effect sound quality? I just find it "looks" so close to the edge of the top. I know this is subjective.
I often draw boxes that have the inside chamfer doing as you describe.
Instead of the sketch here is the drawing. http://wodendesign.com/downloads/CHN40-Compact-ML-V.pdf
dave
Instead of the sketch here is the drawing. http://wodendesign.com/downloads/CHN40-Compact-ML-V.pdf
dave
An ML-Voigt is designated by length, taper, cross-section, restricted terminus, terminus placement and the driver offset (Zd determine the line’s performance. If you move the driver you startgetting more ripple in the bass.
If you are worried, double the top.
dave
If you are worried, double the top.
dave
Many thanks for the drawing, Dave! 🙂 Much better than my lousy sketches (I suppose I should fill you with dread & start plaguing you with new designs again that I've been stacking up... 😉 
)
As Dave says, with these enclosures the physical proportions are functional; doubling the top is a good plan; if I get chance I can see about a new enclosure for the driver.
)As Dave says, with these enclosures the physical proportions are functional; doubling the top is a good plan; if I get chance I can see about a new enclosure for the driver.
Wow Dave, thanks for the extra drawing!
and thank you @Scottmoose for extra explaining. I think I will do as Dave suggested and add another 12mm to the top (double thick). as well as only for a 6mm chamfer. I have modeled it in CAD and I think it looks good!
and thank you @Scottmoose for extra explaining. I think I will do as Dave suggested and add another 12mm to the top (double thick). as well as only for a 6mm chamfer. I have modeled it in CAD and I think it looks good!
Last edited by a moderator: