... the dodecahedron..
Not often i get to post a build in full range 🙂
Eleven 4fe35's on all the faces except for the bottom face, which has the pole mount and four 2" diameter vent ports.
Has strong response down to 60Hz...time to play with port length etc.
Put a quick and nasty tuning on it...kinda suprised how decent it sounds.
And I've truly never heard anything so even anywhere/everywhere in the room.
Time will tell, work to do....
Not often i get to post a build in full range 🙂
Eleven 4fe35's on all the faces except for the bottom face, which has the pole mount and four 2" diameter vent ports.
Has strong response down to 60Hz...time to play with port length etc.
Put a quick and nasty tuning on it...kinda suprised how decent it sounds.
And I've truly never heard anything so even anywhere/everywhere in the room.
Time will tell, work to do....
that's it...i'm selling my woodwork tools and i'm going to take up knitting...all my projects wind up looking like industrial Frankensteins !
seriously nice work!
if they "fill" the room is there a point or reason for a second for stereo?
seriously nice work!
if they "fill" the room is there a point or reason for a second for stereo?
Beautiful woodwork Mark! Can you share build photos of the insides? How is it wired with 11 drivers?
Beautifully done Mark. 
Indeed this speaker does go to 11.
I'm surprised that you are getting 60 Hz out of the 4fe35 driver. Well done.
Indeed this speaker does go to 11. I'm surprised that you are getting 60 Hz out of the 4fe35 driver. Well done.
Oh Wow guys, thanks for all the kind comments...!!!!!
Like said, just fired her up...will post details, meas, wiring etc, asap
Like said, just fired her up...will post details, meas, wiring etc, asap
My college roommate and best friend for a time got his ME Masters working with a speaker like that. He used it as an omni sound source to measure sound attenuation over snow, grass, blacktop. It used these Altec speakers with little aluminum dust caps. I remember he said it was omni up to a certain point, then it "beamed". Probably early 80s, AFAIR.
Nice work! What will you use it for?
Nice work! What will you use it for?
weird I have been thinking omni as well but in the opposite direction using only one small Tannoy DC driver firing up and then play pool with the top end reflections to achieve best results at my seating location. early experiments doing this with a Revolution XT Mini have resulted in impressive stage and image with a realism I have not achieved with direct radiation. not at all an intuitive result but what ever works is good for me.
For some reason I feel like playing D&D with my mates....
Hope they sound as stunning as they look
Hope they sound as stunning as they look
Hi folks, and big thx to all for the kind words.
Here's some followup for those who asked questions..
@ turk182
Don't throw your tools away ! Lol
It wasn't really a very hard build ...i just followed this excellent tutorial
031 How to Build a Dodecahedron - YouTube
Biggest problem with the project was getting drivers...but PE came through
I don't know why I'd make another one for stereo, the way it fills a room..
@ xrk971,
Here's photos of the base and then the inside.
Pretty simple really.
I've wired it using two amp channels. All are 8 ohms.
One channel gets 3 strings in parallel, of 3 drivers per string in series. So 3P, 3S in hornresp speak. The other amp channel gets two drivers in parallel.
I close mic'ed a single driver from each channel to set relative gains.
See a better way to handle 11 drivers?
@Pano,
Yeah, i was happily surprised to see 60 Hz too.
Although I had made the dodo bigger than was needed to simply mount the drivers, trying to get a little over 4 liters per driver for some bottom end extension..
Here's hornresp with the ports i have in the base face.
Here's the first measurement i took yesterday in green, that made me think the 60 Hz goal was accomplished. But now I'm not so sure. The blue trace is a moving mic average of about 3 minutes duration.
Heck, I'm not sure of any measurements right now. I have 3 mics all around dodo, averaging, comparing etc.
This may be a speaker that I throw away measurements and just start tuning by ear 😀
@ jjasniew,
I'm hoping to use it measure room acoustics better. It's never been meant for listening really. Funny, seems your college roommate saw it as a tool too.
Here's some followup for those who asked questions..
@ turk182
Don't throw your tools away ! Lol
It wasn't really a very hard build ...i just followed this excellent tutorial
031 How to Build a Dodecahedron - YouTube
Biggest problem with the project was getting drivers...but PE came through
I don't know why I'd make another one for stereo, the way it fills a room..
@ xrk971,
Here's photos of the base and then the inside.
Pretty simple really.
I've wired it using two amp channels. All are 8 ohms.
One channel gets 3 strings in parallel, of 3 drivers per string in series. So 3P, 3S in hornresp speak. The other amp channel gets two drivers in parallel.
I close mic'ed a single driver from each channel to set relative gains.
See a better way to handle 11 drivers?
@Pano,
Yeah, i was happily surprised to see 60 Hz too.
Although I had made the dodo bigger than was needed to simply mount the drivers, trying to get a little over 4 liters per driver for some bottom end extension..
Here's hornresp with the ports i have in the base face.
Here's the first measurement i took yesterday in green, that made me think the 60 Hz goal was accomplished. But now I'm not so sure. The blue trace is a moving mic average of about 3 minutes duration.
Heck, I'm not sure of any measurements right now. I have 3 mics all around dodo, averaging, comparing etc.
This may be a speaker that I throw away measurements and just start tuning by ear 😀
@ jjasniew,
I'm hoping to use it measure room acoustics better. It's never been meant for listening really. Funny, seems your college roommate saw it as a tool too.
"I don't know why I'd make another one for stereo, the way it fills a room.."
I presume they wouldn't image well anyway?
I presume they wouldn't image well anyway?
i wasn't going to toss me woodworking tools....i hoped to sell them and convert that to scotch for my sorrows...
would 11 LM1875's be crazy...that's what i would want to power a dodacahedron...just to see if shading or beam steering would be possible, maybe....
would a 10:1 transformer work, all drivers in series for 88 ohms
would 11 LM1875's be crazy...that's what i would want to power a dodacahedron...just to see if shading or beam steering would be possible, maybe....
would a 10:1 transformer work, all drivers in series for 88 ohms
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That's my presumption too.
But, despite being omni, they do have a very localized sound.
Aargh...almost makes we want to build another just to see how stereo would sound ...
Yeah, i was just jokin about the 'tossing tools part'....
....although any conversion into scotch sounds like a good trade !!😀
I kinda think the whole purpose of a dodecahedron is to get the geometric omni dispersion.
How/why would you go about any kind of beam steering? Not following your goal...
I also have this gut feel that the angles that exist between faces wouldn't really allow for any steering.
But like said, not visualizing where you may be driving...
(Transformer idea is an interesting solution)
I think it would depend on the size of the space, if the reflections are late and low enough it might work.
Yeah, that makes sense.
And i am listening, in a fairly big space with high vaulted ceilings.