k-401 horns

[RandyH000 5947]

On 11/15/2020 at 4:28 AM, SpeedLimit said:

 perhaps you are ?

OUI -

[WMcD 760]

When I was doing this sort of thing many years ago:  I had a bit of a form with a temporary central piece of 3/4 ply following the curve of the side but a tad smaller.  For the side pieces I had three or four layers of what was sold to me as bending ply which was just very thin ply.  Then slathered a thin layer of yellow glue into the many touching surfaces of the flat sandwich. Like mayo on a triple deck wish sandwich.

 

Then starting at the throat I used drywall screws with washers under the head driven into the curved form to pull the sandwich into shape.  Quite a bit of force necessary.

 

The overall project required quite a bit of triming and patching the screw holes.   It all held together  when the  glue cured. 

 

OTOH I still worried that sometime in the future the internal stresses would cause  the horn to explode into a pile of toothpicks.

 

WMcD

[WMcD 760]

13500/(2.75 x 18.1) =  271.   The K-400 paper by PWK says it doubles in area every 2.75 inches and that means the fc is 271 Hz.  The cut-off wavelength is 18.1 times the length in which area doubles and 13500 in/sec is the speed of sound.  That number might be for the protype and I'm not quite sure that goes for the production model.  But is probably close.

[SpeedLimit 41]

5 hours ago, WMcD said:

13500/(2.75 x 18.1) =  271.   The K-400 paper by PWK says it doubles in area every 2.75 inches and that means the fc is 271 Hz.  The cut-off wavelength is 18.1 times the length in which area doubles and 13500 in/sec is the speed of sound.  That number might be for the protype and I'm not quite sure that goes for the production model.  But is probably close.

Thank's , it's interesting .. i didn't know that.

[SpeedLimit 41]

7 hours ago, WMcD said:

When I was doing this sort of thing many years ago:  I had a bit of a form with a temporary central piece of 3/4 ply following the curve of the side but a tad smaller.  For the side pieces I had three or four layers of what was sold to me as bending ply which was just very thin ply.  Then slathered a thin layer of yellow glue into the many touching surfaces of the flat sandwich. Like mayo on a triple deck wish sandwich.

 

Then starting at the throat I used drywall screws with washers under the head driven into the curved form to pull the sandwich into shape.  Quite a bit of force necessary.

 

The overall project required quite a bit of triming and patching the screw holes.   It all held together  when the  glue cured. 

 

OTOH I still worried that sometime in the future the internal stresses would cause  the horn to explode into a pile of toothpicks.

Yes, i should begin with thinner piece of MDF or plywood ..

[geoff. 775]

This is the kind of thread that could inspire a guy to make his own horns...

 

 

 

 

[SpeedLimit 41]

very hard to bend 6 mm MDF and then maintain in place .. I think i will try with 3 mm MDF for the first layer

 

[SpeedLimit 41]

it easier to bend 3mm MDF

 

i let the glue be dry and will see what it get

 

 

[SpeedLimit 41]

The horns are dry, well rather the glue. I removed the clamps.

It remains to cut the sides of the horns in excess and to sand.

Afterwards, it will be necessary to make the part to connect the driver to the horn.

[mustang_flht 657]

Hello @SpeedLimit

 

Are you making a pair of speakers with a subwoofer in addition to your Cornwall IVs, or is it to put the 401 on it?

 

🙂

 

 

[SpeedLimit 41]

No, mustang_flht, it is for another pair of speakers .. i wanted to try the La Scala. I have already the AL-3 crossovers, i have the pd-5vh atlas sound driver, a pair of b&c de250, a pair of Eminence 15" woofer (kappa 15A), i know it's not the best replacement speakers but perhaps i will try with activ crossover.

 

I would have like to find a pair of k-401 horns but i only see ones in the USA and to ship them to Reunion Island, it is over than 3 times the cost of the parts.

 

in the same time ... i have advanced on my horns

[mustang_flht 657]

Ah! yes I now remember your La Scala project with the Kappa 15A 🙂

 

If you are in active threading you will have no problem with the 15A. The 15C is in 4 ohms and it is used to have the correct level with the Horns in passive filtering, but in active tone 15A 8 Ohms a little less strong will go very very well in my opinion 😋

 

 

[SpeedLimit 41]

if i build the La Scala, perhaps i will buy a pair of Eminence 15C and the B&C DE120or DE10, if i remermber, i have read that they are better working in a clone of the La Scala.

 

but i have also read that the la Scala have a really sound of horn in the basses, something like "nasal" sound ..

[Marvel 5429]

2 hours ago, SpeedLimit said:

but i have also read that the la Scala have a really sound of horn in the basses, something like "nasal" sound ..

 

I believe what you describe is caused by two things. One being vibration from the side walls, and the other from the other from where the two side pathways have parallel sides for ten or so inches (not near mine at the moment). You can stp the physical resonane with a brace or thicker sides. The doghouse sides are solid enough.

 

I've never really noticed it much but I don't play at very high SPLs.

 

Your horns are looking great. You could have made some fine tractrix horns just as easily, but very nice work.

 

Bruce

[RandyH000 5947]

2 hours ago, SpeedLimit said:

No, mustang_flht, it is for another pair of speakers .. i wanted to try the La Scala. I have already the AL-3 crossovers, i have the pd-5vh atlas sound driver, a pair of b&c de250, a pair of Eminence 15" woofer (kappa 15A), i know it's not the best replacement speakers but perhaps i will try with activ crossover.

 

I would have like to find a pair of k-401 horns but i only see ones in the USA and to ship them to Reunion Island, it is over than 3 times the cost of the parts.

 

in the same time ... i have advanced on my horns

 

great work - now they need to be finished ----varnish -stain -or paint

[SpeedLimit 41]

Thank you RandyH000,  my girl friend just painted them .. just the outside.

 

but i am not so proud about my horns. They are not specially well done.

 

i hope it will make the work.

 

Now i have to build the throats

[SpeedLimit 41]

42 minutes ago, Marvel said:

I believe what you describe is caused by two things. One being vibration from the side walls, and the other from the other from where the two side pathways have parallel sides for ten or so inches (not near mine at the moment). You can stp the physical resonane with a brace or thicker sides. The doghouse sides are solid enough.

 

I've never really noticed it much but I don't play at very high SPLs.

i have read that, i have never eard la Scala speakers, so i do not know if what i have read on forums is real or not.

 

44 minutes ago, Marvel said:

Your horns are looking great. You could have made some fine tractrix horns just as easily, but very nice work.

 

oh, oh ... those are my first horns .. and perhaps the last ones. I have no place to work finely. I make that outside my house, near my garage.

I have to carry my tools from up to down my flat .. really not easy and simple.

 

i will do the throats and listen if the horns sounds good with the atlas sound drivers .. if not, i will wait until i find a pair of k-401, or k-400 or speakerlab h350 horns.

[RandyH000 5947]

29 minutes ago, SpeedLimit said:

Thank you RandyH000,  my girl friend just painted them .. just the outside.

 

but i am not so proud about my horns. They are not specially well done.

 

i hope it will make the work.

 

Now i have to build the throats

some people veneer the MDF horns with exotic woods ,  being the MDF is so flat ,------I think they look better than my metal K400 ---Wood has a much better tone and the sound is  natural -

[geoff. 775]

I think those are a fine first foray into DIY horns. Certainly worth the effort and experience. Very inspiring.

 

Something just occurred to me looking at the pictures a couple posts back...

 

If the excess side walls were left untrimmed in a set of DIY horns they might serve as stands? 

[SpeedLimit 41]

14 minutes ago, RandyH000 said:

some people veneer the MDF horns with exotic woods ,  being the MDF is so flat ,------I think they look better than my metal K400 ---Wood has a much better tone and the sound is  natural -

Yes i would have prefered exotic woods but on my little island, wood is very expensive. This is why i did make them with MDF.

and i was no sure to be able to make them 😀