Hi all,
I am new to the DIYaudio-forum and would like to introduce myself with this thread.
After having built my first DIY-Loudspeakers with multiple layers of MDF (see thread on homecinema-fr.com in FRENCH ) I rapidly wanted to validate the assembly method with threaded rods on a bigger loudspeaker.
At this moment the loudspeakers are built up, run in (around 250 hours I guess) and waiting for their paint-job before getting a new home in my parents living-room.
They were actually a present for my father's birthday on September 8.
I decided on going with a pair of 3-way loudspeakers "inspirated" by the PMS-project from Troels Gravesen using SEAS Prestige speakers.
Have a look at his PMS-project here.
I want to thank Mr. Gravesen for putting his excellent work online, making it available to all of us.
I started designing the cabinets on my return from holidays on August 2 and it took me about 15 hours to complete (i.e. 3 "night shifts" beside my everyday daylight job), machining has been done on August 6 & 7.
The loudspeakers were put in service one month later, the day before his birthday, having taken care to start running in all the speakers on the first completed cabinet. Mono sound in the workshop...
As for the first set of speakers (see link above) the cabinets are designed of multiple layers of MDF (exclusively CNC-machined) and assembled with the help of threaded rods.
When realizing the SA2K-Clone I had noticed several points that could be optimized referring to both machining and assembly.
Modifications for the PMS concerned milling cutter types, assembly tolerances on the front-plates, anticipation of dilatation and some more.
The speakers used are CA22RNX, MCA15RLY and the well-known T27TFFC, the cross-over will be as per Mr. Gravesen's layout.
All cross-over parts have been chosen with a fair quality in order to keep costs in the budget... audyn cap KP-QS 630V, IT air core 14/10 and 10/10. Only RC and RLC are fitted with bi-polars and "cheap" stuff.
Enough talking, here are the first pics:
View on the working CNC-machine
Giving you an idea of the layout plan
The scrapings after machining one board (3 bins of 70 liters in total)
MDF-Fishbones
Who said "sexy" ?
First box full of puzzle-pieces
Another view
All of them... which will have to get brushed to get all the dust out
Although the pic is dark you can see that the central slot is totally clogged
I am new to the DIYaudio-forum and would like to introduce myself with this thread.
After having built my first DIY-Loudspeakers with multiple layers of MDF (see thread on homecinema-fr.com in FRENCH ) I rapidly wanted to validate the assembly method with threaded rods on a bigger loudspeaker.
At this moment the loudspeakers are built up, run in (around 250 hours I guess) and waiting for their paint-job before getting a new home in my parents living-room.
They were actually a present for my father's birthday on September 8.
I decided on going with a pair of 3-way loudspeakers "inspirated" by the PMS-project from Troels Gravesen using SEAS Prestige speakers.
Have a look at his PMS-project here.
I want to thank Mr. Gravesen for putting his excellent work online, making it available to all of us.
I started designing the cabinets on my return from holidays on August 2 and it took me about 15 hours to complete (i.e. 3 "night shifts" beside my everyday daylight job), machining has been done on August 6 & 7.
The loudspeakers were put in service one month later, the day before his birthday, having taken care to start running in all the speakers on the first completed cabinet. Mono sound in the workshop...
As for the first set of speakers (see link above) the cabinets are designed of multiple layers of MDF (exclusively CNC-machined) and assembled with the help of threaded rods.
When realizing the SA2K-Clone I had noticed several points that could be optimized referring to both machining and assembly.
Modifications for the PMS concerned milling cutter types, assembly tolerances on the front-plates, anticipation of dilatation and some more.
The speakers used are CA22RNX, MCA15RLY and the well-known T27TFFC, the cross-over will be as per Mr. Gravesen's layout.
All cross-over parts have been chosen with a fair quality in order to keep costs in the budget... audyn cap KP-QS 630V, IT air core 14/10 and 10/10. Only RC and RLC are fitted with bi-polars and "cheap" stuff.
Enough talking, here are the first pics:
View on the working CNC-machine
An externally hosted image should be here but it was not working when we last tested it.
Giving you an idea of the layout plan
An externally hosted image should be here but it was not working when we last tested it.
The scrapings after machining one board (3 bins of 70 liters in total)
An externally hosted image should be here but it was not working when we last tested it.
MDF-Fishbones
An externally hosted image should be here but it was not working when we last tested it.
Who said "sexy" ?
An externally hosted image should be here but it was not working when we last tested it.
First box full of puzzle-pieces
An externally hosted image should be here but it was not working when we last tested it.
Another view
An externally hosted image should be here but it was not working when we last tested it.
All of them... which will have to get brushed to get all the dust out
An externally hosted image should be here but it was not working when we last tested it.
Although the pic is dark you can see that the central slot is totally clogged
An externally hosted image should be here but it was not working when we last tested it.
Some more pics
Bits 'n pieces...every piece gets some brushing and a quick grind with abrasive paper..getting tanned at the same time
What it looks like once cleaned up
Bits 'n pieces...every piece gets some brushing and a quick grind with abrasive paper..getting tanned at the same time
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
What it looks like once cleaned up
An externally hosted image should be here but it was not working when we last tested it.
Here we go, having a closer look at the different parts.
First the floor-stand assembly.
Connecting plates from speaker bottom-plate to the floor plate , giving the PMS a 5° tilt backwards
Speakers bottom-plate with grooves for the connecting plates above and holes for the vents
Floor-plate with grooves for connecting plates
Dry assembled bottom-plate of the speaker
The whole floor-stand assembly
More to come...
First the floor-stand assembly.
Connecting plates from speaker bottom-plate to the floor plate , giving the PMS a 5° tilt backwards
An externally hosted image should be here but it was not working when we last tested it.
Speakers bottom-plate with grooves for the connecting plates above and holes for the vents
An externally hosted image should be here but it was not working when we last tested it.
Floor-plate with grooves for connecting plates
An externally hosted image should be here but it was not working when we last tested it.
Dry assembled bottom-plate of the speaker
An externally hosted image should be here but it was not working when we last tested it.
The whole floor-stand assembly
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
More to come...
Going on with the other parts.
The Front-plate which will receive the midrange-driver MCA15RLY and the tweeter T27TFFC. Design goals were flush-mounting both of the drivers and backside ventilation of the mid.
Front-side view
Back-side view
Same story for the woofer CA22RNX
and the back-side view
The Front-plate which will receive the midrange-driver MCA15RLY and the tweeter T27TFFC. Design goals were flush-mounting both of the drivers and backside ventilation of the mid.
Front-side view
An externally hosted image should be here but it was not working when we last tested it.
Back-side view
An externally hosted image should be here but it was not working when we last tested it.
Same story for the woofer CA22RNX
An externally hosted image should be here but it was not working when we last tested it.
and the back-side view
An externally hosted image should be here but it was not working when we last tested it.
Construction layout of the speakers is, as mentioned in the header, piling up multiple layer of MDF, commonly called trans-lamination/stack-lamination as stated by Brett earlier in this thread.
In order to create the volume for the midrange and to strengthen the speaker construction certain parts are designed so that they cover the whole periphery of the speaker, actually like a (more or less) full slice.
Others parts, in order to optimize raw material consumption (see layout plan in the very first pictures of this thread) are designed as 1/2 or 1/4. The pics will show it better than words.
The top layer sealing the cabinet
The layer used to seal the volume for the mid, 2 per cabinet, i.e. upper and lower enclosure.
The layer used to create the volume for the mid. Design is "rounded" in order to minimize standing waves. Only the layers forming the upper and lower enclosure(see above) have parallel faces, making it 2 compared to 6 in a more classic square cabinet.On top of the picture you can clearly see the notch for the insertion of the front-plate.
There's a total of 10 of those layers per cabinet, 7 to form the enclosure for the mid, 2 behind the woofer and finally 1 in the upper part of the cabinet used for bracing.
The layer bracing the woofer on the upper and lower side. 2 used per cabinet, the LPF will be fixed to the lower one.
That's it for the peripheral parts.
In order to create the volume for the midrange and to strengthen the speaker construction certain parts are designed so that they cover the whole periphery of the speaker, actually like a (more or less) full slice.
Others parts, in order to optimize raw material consumption (see layout plan in the very first pictures of this thread) are designed as 1/2 or 1/4. The pics will show it better than words.
The top layer sealing the cabinet
An externally hosted image should be here but it was not working when we last tested it.
The layer used to seal the volume for the mid, 2 per cabinet, i.e. upper and lower enclosure.
An externally hosted image should be here but it was not working when we last tested it.
The layer used to create the volume for the mid. Design is "rounded" in order to minimize standing waves. Only the layers forming the upper and lower enclosure(see above) have parallel faces, making it 2 compared to 6 in a more classic square cabinet.On top of the picture you can clearly see the notch for the insertion of the front-plate.
An externally hosted image should be here but it was not working when we last tested it.
There's a total of 10 of those layers per cabinet, 7 to form the enclosure for the mid, 2 behind the woofer and finally 1 in the upper part of the cabinet used for bracing.
The layer bracing the woofer on the upper and lower side. 2 used per cabinet, the LPF will be fixed to the lower one.
An externally hosted image should be here but it was not working when we last tested it.
That's it for the peripheral parts.
Picture regrouping the different parts not being peripheral.
On top one of the elements forming the rear of the cabinet.
Then one element forming the front of the cabinet.
And last the elements for the front where the front-plates for the drivers are situated.
On top one of the elements forming the rear of the cabinet.
Then one element forming the front of the cabinet.
And last the elements for the front where the front-plates for the drivers are situated.
An externally hosted image should be here but it was not working when we last tested it.
Let's finish the floor-stand:
The bottom-plate with 2 alloy brackets that will help to securely fix the floor-plate assembly to it
Connecting plates in the grooves of the bottom-plate, hold in place by 4 x 4mm screws
The finished assembly, grooves filled with a mixture of glue and woodsaw (had some left actually
), alloy brackets in place
First binding post
And both of them
The bottom-plate with 2 alloy brackets that will help to securely fix the floor-plate assembly to it
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Connecting plates in the grooves of the bottom-plate, hold in place by 4 x 4mm screws
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
The finished assembly, grooves filled with a mixture of glue and woodsaw (had some left actually
), alloy brackets in placeAn externally hosted image should be here but it was not working when we last tested it.
First binding post
An externally hosted image should be here but it was not working when we last tested it.
And both of them
An externally hosted image should be here but it was not working when we last tested it.
Some pics of the crossovers:
Caps in // with ferrit core selfs
Caps in // with ferrit core selfs
An externally hosted image should be here but it was not working when we last tested it.
Yes, MDF is 25mm is this case but not restrictive at all, thicker plates can be used. Dimensional stability has been taken into account, as an example I might quote "front-plate adjustments" ...
Creating component sub-assemblies for the mid-tweet crossover
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Installation of the cross-over components on the perspex boards. Holes are drilled to hold the components in place with zip ties.
Placement and orientation of the coils are as per the observation of Troels on his website. Have a look here:Placement of coils in crossover networks:
Figure 6 applies for the central coil to the 2 outer ones and figure 1 for the outer ones to each other.
Cutting the perspex board and drilling the holes
Holes drilled
Some parts installed
All of them installed
Placement and orientation of the coils are as per the observation of Troels on his website. Have a look here:Placement of coils in crossover networks:
Figure 6 applies for the central coil to the 2 outer ones and figure 1 for the outer ones to each other.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Cutting the perspex board and drilling the holes
An externally hosted image should be here but it was not working when we last tested it.
Holes drilled
An externally hosted image should be here but it was not working when we last tested it.
Some parts installed
An externally hosted image should be here but it was not working when we last tested it.
All of them installed
An externally hosted image should be here but it was not working when we last tested it.
Every cleaned up (more or less) for soldering the cross-overs
First one done
Some hot melt glue helps holding wires and parts in place
Finished cross-over
The other one. Looks just the same, besides the white colored tape (no particular reason, I only ran out of black one)
An externally hosted image should be here but it was not working when we last tested it.
First one done
An externally hosted image should be here but it was not working when we last tested it.
Some hot melt glue helps holding wires and parts in place
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Finished cross-over
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
The other one. Looks just the same, besides the white colored tape (no particular reason, I only ran out of black one)
An externally hosted image should be here but it was not working when we last tested it.
Waveflex, it looks like you're doing wonderful work. Seems like pre-stressed concrete in a way once you tighten down the threaded rod?
But it appears you have weakened the loudspeaker where it needed strength the most: at the baffle openings. Perhaps there is bracing to compensate? (I understand that you were trying to improve airflow.)
(The same might apply to removing material from the center of the angled legs?)
But it appears you have weakened the loudspeaker where it needed strength the most: at the baffle openings. Perhaps there is bracing to compensate? (I understand that you were trying to improve airflow.)
(The same might apply to removing material from the center of the angled legs?)
Thanks for your appreciation of the project Tosh.
I will post the assembly of the different parts shortly, as mentioned earlier in this post there's indeed some bracing. Honestly airflow was not really an issue as far as the legs are concerned...
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