Hi everyone, full disclosure this is my first post in DIYAudio
I'd like to share a project I'm working : building a reasonably good sounding BeoLab look-alike.
I started by downloading every picture I could find on these speakers but there was surprisingly very little description of the drivers/enclosure details.
I found these pictures and later on found a pdf from B&O that is vector graphic, allowing me to zoom in, scale and take measurements.
In the next few posts (please forgive me this project is going slowly) I'll take you along my build.
I'd like to share a project I'm working : building a reasonably good sounding BeoLab look-alike.
I started by downloading every picture I could find on these speakers but there was surprisingly very little description of the drivers/enclosure details.
I found these pictures and later on found a pdf from B&O that is vector graphic, allowing me to zoom in, scale and take measurements.
In the next few posts (please forgive me this project is going slowly) I'll take you along my build.
Attachments
BO 18 - part 1 - Body
So I decided to scale the Beolab 18 a bit in order to help with driver selection.
At the early stage of the project, I had still no clue what drivers to use for this project (mid range or tweeters) so I wanted to have maximum versatility.
The original Beolabs use 4" mid range and the body itself seems to be 4". I purchased online a 8 foot long aluminum tube of 5" OD, 1/4" wall (from onlinemetals.com).
I cut the tube in half then mounted it on my wood lathe with my bed extension and was able to sand and polish it to a quite mirror-like finish. It isn't perfect but it will same me tons of time at the end.
I then build a jig to rip and cross cut the tubes on my table saw in order to accommodate a flat panel (also 1/4" aluminum). I wanted to keep a round section (37mm / about 1.5") in order to help mount the tweeters later.
So I decided to scale the Beolab 18 a bit in order to help with driver selection.
At the early stage of the project, I had still no clue what drivers to use for this project (mid range or tweeters) so I wanted to have maximum versatility.
The original Beolabs use 4" mid range and the body itself seems to be 4". I purchased online a 8 foot long aluminum tube of 5" OD, 1/4" wall (from onlinemetals.com).
I cut the tube in half then mounted it on my wood lathe with my bed extension and was able to sand and polish it to a quite mirror-like finish. It isn't perfect but it will same me tons of time at the end.
I then build a jig to rip and cross cut the tubes on my table saw in order to accommodate a flat panel (also 1/4" aluminum). I wanted to keep a round section (37mm / about 1.5") in order to help mount the tweeters later.
Attachments
DIY Beolab 18 - part 3 - the legs
Onto the legs, the original Beolabs have an aluminum leg cut on the CNC lathe.
I initaly contemplated casting the legs in aluminum and then finishing them on the lathe but my metal lathe is manual and I these speakers will stay in our living room so wood was preferred over aluminum.
I glued up 3 sections of 8/4 hard maple and mounted them on a face plate on my wood lathe.
I turned the outside profile to my liking (very subjective but I like the slight s-profile rather than a straight taper).
I then bored a 3" hole 6" deep that I plan to fill with metal to add mass. Boring this hole on the lathe with a forstner bit was pretty difficult.
I then finished the legs on the lathe with several coats of clear lacquer to keep the light maple color.
I then turned a 3" diameter, 6" long piece of mild steel on my metal lathe and drilled it to accommodate the 1/2" threaded rod
Onto the legs, the original Beolabs have an aluminum leg cut on the CNC lathe.
I initaly contemplated casting the legs in aluminum and then finishing them on the lathe but my metal lathe is manual and I these speakers will stay in our living room so wood was preferred over aluminum.
I glued up 3 sections of 8/4 hard maple and mounted them on a face plate on my wood lathe.
I turned the outside profile to my liking (very subjective but I like the slight s-profile rather than a straight taper).
I then bored a 3" hole 6" deep that I plan to fill with metal to add mass. Boring this hole on the lathe with a forstner bit was pretty difficult.
I then finished the legs on the lathe with several coats of clear lacquer to keep the light maple color.
I then turned a 3" diameter, 6" long piece of mild steel on my metal lathe and drilled it to accommodate the 1/2" threaded rod
Attachments
DIY Beolab 18 - part 4 - the feet
For the feet, I got a very nice piece of 12/4 hard maple, milled it to dimensions and then cut a large bevel on all faces of the top.
I then routed a recess in the bottom, 1-1/8" deep and about 8"x6" wide.
I inserted a plate of steel - 8"x6"x1" for stability and welded the threaded rod on this plate.
The threaded rod (1/2" ) is welded to the metal plate, goes thru the foot, the leg and will go thru a plate to attach the tube body.
For the feet, I got a very nice piece of 12/4 hard maple, milled it to dimensions and then cut a large bevel on all faces of the top.
I then routed a recess in the bottom, 1-1/8" deep and about 8"x6" wide.
I inserted a plate of steel - 8"x6"x1" for stability and welded the threaded rod on this plate.
The threaded rod (1/2" ) is welded to the metal plate, goes thru the foot, the leg and will go thru a plate to attach the tube body.
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DIY Beolab 18 - part 5 - Attaching the leg/foot/body
To attach the body to the threaded rod coming form the foot, I planned to weld a plate at the bottom.
I purchased a piece of 1" thick aluminum plate, traced, cut and sand it on the belt sander until it fit inside the tube.
I then tried to weld it to the body. Only to realized that I couldn't weld aluminum to save my life. I have a friend come over to troubleshoot my welder and give me pointers (hats off to Chris at Specialized Industrial Services LLC in Orange City Florida - amazing welder and fabricator)
I was then able to "weld" the bottom plates and the tabs that will hold the face. Of course anyone looking at my welds will laugh for hours but it seems to hold !
At this point the speakers are floor standing and I could focus on driver selection !
To attach the body to the threaded rod coming form the foot, I planned to weld a plate at the bottom.
I purchased a piece of 1" thick aluminum plate, traced, cut and sand it on the belt sander until it fit inside the tube.
I then tried to weld it to the body. Only to realized that I couldn't weld aluminum to save my life. I have a friend come over to troubleshoot my welder and give me pointers (hats off to Chris at Specialized Industrial Services LLC in Orange City Florida - amazing welder and fabricator)
I was then able to "weld" the bottom plates and the tabs that will hold the face. Of course anyone looking at my welds will laugh for hours but it seems to hold !
At this point the speakers are floor standing and I could focus on driver selection !
Attachments
No I have never heard them. However my dad has a pair of the older 800.
The principle is the same -TMM- but of course the BeoLab18 have a distinctive acoustic diffuser for the tweeter.
I did a very detailed sketchup drawing (can't upload it here unfortunately)
Only when I had the details figured out on sketchup did I look for material and start the build,
DIY Beolab 18 - part 6 - Driver selection
So the original B&O speakers are 4" diameter body, housing 2x 4" mid range and 1x 3/4" tweeter on top.
Reading many forums I believe B&O uses custom specified ScanPeak drivers and I did contemplated purchasing these but like I mentioned I have more latitude in driver selection because the body is not 5" diameter.
I calculated the raw volume of the body to be 9.74 litres/ 0.34 cu ft so I looked for mid range that would take advantage of large volume. With a help of a friend, we settled on the Morel EM428 mid range and EM338 tweeters
Morel EM 428 4" DPC Cone Midrange
and tweeters:
Morel ET 338 1-1/8" Soft Dome Tweeter Matched Pair
I postponed any work on the body until I received the actual parts and make my own measurements (dome width and height,...)
So the original B&O speakers are 4" diameter body, housing 2x 4" mid range and 1x 3/4" tweeter on top.
Reading many forums I believe B&O uses custom specified ScanPeak drivers and I did contemplated purchasing these but like I mentioned I have more latitude in driver selection because the body is not 5" diameter.
I calculated the raw volume of the body to be 9.74 litres/ 0.34 cu ft so I looked for mid range that would take advantage of large volume. With a help of a friend, we settled on the Morel EM428 mid range and EM338 tweeters
Morel EM 428 4" DPC Cone Midrange
and tweeters:
Morel ET 338 1-1/8" Soft Dome Tweeter Matched Pair
I postponed any work on the body until I received the actual parts and make my own measurements (dome width and height,...)
Attachments
Last edited:
DIY Beolab 18 - part 7 - Tweeter holder
So I needed a holder for the tweeters that will keep them facing up, with the dome as close as possible to the surface.
The top surface must also be super flat to later on accommodate the acoustic diffuser (I plan to 3D print and cast the acoustic diffuser in aluminum)
I chucked up a piece of 5 1/2" by ~ 4" long aluminum rod and turned on my metal lathe a recess that will accommodate the tweeter and a tenon so that they will slip into the body top.
I wanted the dome to come as close as possible to the top surface and had to settle for ~3mm because the tweeters came with 3 screws on top that protrudes ~1mm. I had to cut a groove in the underside so couldn't thin the top any further.
Part turned great - I still need to turn the second one !
So I needed a holder for the tweeters that will keep them facing up, with the dome as close as possible to the surface.
The top surface must also be super flat to later on accommodate the acoustic diffuser (I plan to 3D print and cast the acoustic diffuser in aluminum)
I chucked up a piece of 5 1/2" by ~ 4" long aluminum rod and turned on my metal lathe a recess that will accommodate the tweeter and a tenon so that they will slip into the body top.
I wanted the dome to come as close as possible to the top surface and had to settle for ~3mm because the tweeters came with 3 screws on top that protrudes ~1mm. I had to cut a groove in the underside so couldn't thin the top any further.
Part turned great - I still need to turn the second one !
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That's a very ambitious build. Looks amazing, keep the pics coming.
I wish a had a shop outfitted as well as yours 🙂
Why did you pick this particular design ?
I wish a had a shop outfitted as well as yours 🙂
Why did you pick this particular design ?
Ambitious for sure. I simply like the design a lot and being an amateur woodworker I was looking for a design of speaker that would highlight wood without the obvious "burl veneer" in your face that you mostly see in high end enclosure.
The design incorporate wood, metal, aluminum and should fit nicely in our living room.
And last but not least I got MA (Management Approval) by my wife 🙂
The shop is the result of >10yrs of tool collecting in woodworking and I just recently started to add metal working tools - can't wait to have a CNC mill (one day !)
Long overdue update - top acoustic diffuser
With our kids turning 3 and 1yo - nights have been busy and not really shop-busy.
However today I will walk you thru the design and realization of the top acoustic diffusers. Their purpose is to send to the listener the high range coming from the tweeters as they are facing up.
I originally printed them on my 3D printer to get a feel and tweak the design and dimensions.
But I know I wanted them in aluminum to match the rest of the body.
So I setup to make a lost-PLA mold with the intend to cast them in aluminum. I'll spare you the details but that was never successful then I tried making a wax part out of a silicone mold with the hlep of a friend. Again not very successful.
Then I bought a CNC, took about 4 month to learn CAD/CAM (Fusion360) and after many broken end mills and a few crashes - I was able to get these 2 beauties
With our kids turning 3 and 1yo - nights have been busy and not really shop-busy.
However today I will walk you thru the design and realization of the top acoustic diffusers. Their purpose is to send to the listener the high range coming from the tweeters as they are facing up.
I originally printed them on my 3D printer to get a feel and tweak the design and dimensions.
But I know I wanted them in aluminum to match the rest of the body.
So I setup to make a lost-PLA mold with the intend to cast them in aluminum. I'll spare you the details but that was never successful then I tried making a wax part out of a silicone mold with the hlep of a friend. Again not very successful.
Then I bought a CNC, took about 4 month to learn CAD/CAM (Fusion360) and after many broken end mills and a few crashes - I was able to get these 2 beauties
Attachments
vertical acoustic diffuser
The 2nd acoustic diffuser (for the midrange/woofers) are a little bit easier to do.
I 3D printed brackets to hold the wooden slats. Then 3D printed retention clips that will hold the brackets onto the speaker face plate.
Finally I milled and fitted the wooden slats into the brackets. I added a curve going from center to edges add the bottom for esthetic purpose.
Last but not least the first and last slats will be help in place with magnets (haven't done that yet)
The 2nd acoustic diffuser (for the midrange/woofers) are a little bit easier to do.
I 3D printed brackets to hold the wooden slats. Then 3D printed retention clips that will hold the brackets onto the speaker face plate.
Finally I milled and fitted the wooden slats into the brackets. I added a curve going from center to edges add the bottom for esthetic purpose.
Last but not least the first and last slats will be help in place with magnets (haven't done that yet)
Attachments
Bonus post - when you have a lathe...
When you have a lathe there is no shortage of projects...
For instance I could have purchased some terminals for the speakers but I guess the perspective of turning them from solid brass was very tempting.
A nice evening in the shop
When you have a lathe there is no shortage of projects...
For instance I could have purchased some terminals for the speakers but I guess the perspective of turning them from solid brass was very tempting.
A nice evening in the shop
Attachments
The part where I need your help
Hi folks, one of the reason I posted this project here - beside sharing the fun - is to ask for some advise on the crossover design.
With the mechanical part of the build almost done, I'll be turning my attention to the cross-over design and realization.
I have selected these midrange/woofers
Morel EM 428 4" DPC Cone Midrange
and these tweeters
Morel ET 338-104 1-1/8" Soft Dome Tweeter Matched Pair
Before you suggest other speakers, please consider the fact that the mechanical design of the enclosures is custom fitted to these parts and I do not want to change them right now.
Having said that it seems to me - looking at the spec that the natural crossover point for these components should be 3kHz but I'd like your opinion on lower it to say 2.5 or even 2Khz in order to better use the tweeters.
I'm considering buying off the shelf crossovers like this one
Dayton Audio XO2W-3K 2-Way Speaker Crossover 3,000 Hz
Would you recommend against it and would I get better performance with custom made one ?
Last burning question, the original design from B&O is vented with a port in the front of the speaker (there is a funnel connecting the opening below the bottom mid range and the front of the speaker - see first post for picture). Do you think this is a good idea - I have a larger volume to start with but I can easily 3D print a port as well.
Hi folks, one of the reason I posted this project here - beside sharing the fun - is to ask for some advise on the crossover design.
With the mechanical part of the build almost done, I'll be turning my attention to the cross-over design and realization.
I have selected these midrange/woofers
Morel EM 428 4" DPC Cone Midrange
and these tweeters
Morel ET 338-104 1-1/8" Soft Dome Tweeter Matched Pair
Before you suggest other speakers, please consider the fact that the mechanical design of the enclosures is custom fitted to these parts and I do not want to change them right now.
Having said that it seems to me - looking at the spec that the natural crossover point for these components should be 3kHz but I'd like your opinion on lower it to say 2.5 or even 2Khz in order to better use the tweeters.
I'm considering buying off the shelf crossovers like this one
Dayton Audio XO2W-3K 2-Way Speaker Crossover 3,000 Hz
Would you recommend against it and would I get better performance with custom made one ?
Last burning question, the original design from B&O is vented with a port in the front of the speaker (there is a funnel connecting the opening below the bottom mid range and the front of the speaker - see first post for picture). Do you think this is a good idea - I have a larger volume to start with but I can easily 3D print a port as well.
After all that work you definitely can do better than buy a generic crossover. It would take (probably many) measurements though. Using a program like X-SIM would allow you to get it right. It would be a shame not to do it right.
Awesome fabrication skills, you could move to digital processing to do crossover work, get some DSP capable amplifiers to compliment this set. It might even allow a Linkwitz Transform so you don't need a port. How low do you want these to play? I guess they will get some support from subwoofer(s)?
A port should really be simulated to get it close (enough) to where it should be. Usually that happens before the build 😉.
I am surprised you get so little response, I really like your work here! 🙂
Fantastic project, but with your skill i would reconsider the bottom wooden cone and base and diffusors for an all aluminum enclosure
I though about it as well but wait until you see the vertical wooden acoustic diffuser - they complement the wood very nicely - should be able to post a picture soon.
Thanks for your comment
Thanks a lot for the suggestions - I can definitely simulate the crossover, I wasn't sure where to start as far as loading the actual speaker impedance but I'm going to have a look at your suggestions - many many thanks for your inputs.
Pierre
Pierre