hi
i did not read any of the posts above but i can highly recommend concrete subwoofer i once made one about 15-18 years ago still works great and i never surpassed it will all the other subwoofers i built afterwards pitty is i had to leave it behing in czechoslovakia since i moved to us many sobwoofers i have built since than but none like that one it was designed with four 12" woofers in two pairs arranged as two isobaricks per side in push pull or bipolar application by single switch four highly efficient woofers made in old socialistic czechoslovakia were great the enclosure was a square box made of tiles holded together by a thick concrete wall whole enclosure was one concrete block called monolith i still have that article i followed the enclosure was so heavy i could not move it myself i had to call my brother to move it to final place still there after all those years see ya all good buy good luck with more concrete subwoofers i highly recommend
ed
i did not read any of the posts above but i can highly recommend concrete subwoofer i once made one about 15-18 years ago still works great and i never surpassed it will all the other subwoofers i built afterwards pitty is i had to leave it behing in czechoslovakia since i moved to us many sobwoofers i have built since than but none like that one it was designed with four 12" woofers in two pairs arranged as two isobaricks per side in push pull or bipolar application by single switch four highly efficient woofers made in old socialistic czechoslovakia were great the enclosure was a square box made of tiles holded together by a thick concrete wall whole enclosure was one concrete block called monolith i still have that article i followed the enclosure was so heavy i could not move it myself i had to call my brother to move it to final place still there after all those years see ya all good buy good luck with more concrete subwoofers i highly recommend
ed
I use 12 gallon Cortico plastic boxes to make my concrete woofers. However, it takes about a week to make all 6 sides, but the technology is much simpler... A front panel made of plywood with many screws (steel reinforcement), bolts for speakers are glued by epoxy.
There are woofers, 12 inch drivers, for frequencies 30-160 Hz. Subwoofer is under the floor, a concrete horn buried in sand, with a grill that opens to the room. It works down from 30 Hz shaking sofas. Very impressive!
There are woofers, 12 inch drivers, for frequencies 30-160 Hz. Subwoofer is under the floor, a concrete horn buried in sand, with a grill that opens to the room. It works down from 30 Hz shaking sofas. Very impressive!
Here is the mouth of the subwoofer that works below 30 Hz. The whole construction reminds Patephone, there was such a compact gramophone with a horn inside of a box. Unlike a gramophone, it shakes sofas very effectively... A peace of wall above is made of 2 inch MDF covered by memoryfoam & vinyl.
hi wavebourn,have any more pics?or info?
you said in your post that it took a week to finish 6 sides.does that mean you poured 1 side at a time? and how did it hold up?i ask because i find that new concrete does not bond that well with already set concrete.did you use rebar or a bonding agent?regular 3000 psi concrete?
being a mason for almost 20 years , this is a concept i've always been interested in and have my own ideas about.more info and impressions would be great
thanks
glen
you said in your post that it took a week to finish 6 sides.does that mean you poured 1 side at a time? and how did it hold up?i ask because i find that new concrete does not bond that well with already set concrete.did you use rebar or a bonding agent?regular 3000 psi concrete?
being a mason for almost 20 years , this is a concept i've always been interested in and have my own ideas about.more info and impressions would be great
thanks
glen
I know Glen that monolithic box would be more robust than made such a way, but it is DIY and I made it from materials in hands using "Made In USA Garage" technology. However, foundry under a pressure similar to ancient Egyptian technology would be nice to have...
I used a cheap Quickrete mix from Ace Hardware
I used a cheap Quickrete mix from Ace Hardware
One more idea: a steel basket inside of a plastic form. My brother is a construction engineer and he used to build towers such a way (25 store round hotel and 19 store building of a complex form)
After Chernobyl catastrophe both projects were frozen because all cement was going to Ukraine for the sarcophagus, after that Perestroika happened and government did not want to spend money on that projects anymore... I should definitely call him and ask his professional opinion about speakers.
After Chernobyl catastrophe both projects were frozen because all cement was going to Ukraine for the sarcophagus, after that Perestroika happened and government did not want to spend money on that projects anymore... I should definitely call him and ask his professional opinion about speakers.
hi wavebourn,i would also use reinforcing steel, and a single pour.the plan in the back of my mind is is to make the walls 2.5-3 inches thick with lots of steel, possibly round enclosure.rather that regular concrete i would use none shrink grout(available at home depot) with gravel.regular concrete is usually between 300-5000 psi,but this stuff is over 10,000 psi.my concern is weather the higher strength is better or worst as it may ring more that lower psi concrete.
how would you compare your concrete box to mdf?
another idea is to build a brick box.i was thinking of using a softer brick with a hard mortar which might help to dampen the box.the bricks are 4"deep,thus walls that are 4" thick.and maybe the top/bottom would be concrete.some with would have 3 different strenghs: brick-500 psi,mortar-1800psi and concrete -500-10000 psi.
just some thoughts.
how would you compare your concrete box to mdf?
another idea is to build a brick box.i was thinking of using a softer brick with a hard mortar which might help to dampen the box.the bricks are 4"deep,thus walls that are 4" thick.and maybe the top/bottom would be concrete.some with would have 3 different strenghs: brick-500 psi,mortar-1800psi and concrete -500-10000 psi.
just some thoughts.
There are many additives for cement/concrete. A "plasticis(z)er" is liquid designed to allow concrete to shrink in the cold without cracking, and makes it slightly rubbery, so reduces chance of cracking if speaker dropped and helps to stop ringing.
Alternatively - adding pellets of plastic or rubber would have the same effect. I tried to get some of that rubber used for kids playgrounds.I could not find anything suitable at time so just used plasticiser.
I used steel reinforcing (only because i could!!) In hind-site i dont think it was nessesary, Its not like its taking any weight or being stressed.
If its thick enough - no ringing
I agree a tube is the optimum design, and not too difficult to achieve.
Alternatively - adding pellets of plastic or rubber would have the same effect. I tried to get some of that rubber used for kids playgrounds.I could not find anything suitable at time so just used plasticiser.
I used steel reinforcing (only because i could!!) In hind-site i dont think it was nessesary, Its not like its taking any weight or being stressed.
If its thick enough - no ringing
I agree a tube is the optimum design, and not too difficult to achieve.
If it is ringing it is ringing on frequencies far away from what it reproduces. Subwoofer is not a military fortification; nobody is going to bomb it. Temperature variations inside of the house is not enough to damage it...
Speaking of tubes, you may go further and make a Church Organ. Tubes resonate well.
Build one and check, it is much more productive than discuss theoretically forever...
Speaking of tubes, you may go further and make a Church Organ. Tubes resonate well.
Build one and check, it is much more productive than discuss theoretically forever...
woolly said:
Hint: glue several levels of linoleum to surfaces if you are afraid of ringings... Anyway walls and furniture around will ring much-much louder. But it is not necessary bad: shaking sofas impress guests when they watch movies in my house (ringing floor) more than quality of sound itself...
Here is one of 2 woofers that are standing under my in-wall line arrays. They work from 40 to 200 Hz (Fs = 35 Hz). They are heavy and solid like a rock, so surfaces don't vibrate at all, only speaker cones treated by a composite material are pumping. Very fast and soft bass. I will never ever use wood or plywood or any plastic for stationary speakers. Fireplaces and speakers have to be built in-house.
i whas thinking of a concept, i wanted to make one cabinet out of serveral layers like this.
its like a floorstanding speaker but then cut vertical in piecs like 10 cm only the piece where the driver is,is of one piece ofcource.
so you have a bottom a top ,a piece with the driver, and a piece blank with no holes just to add volume to the enclosure.
now you can arrange then as you wish also you can increase and decrease the internal volume so you can make monitors with the same molds as well as floorstanders just ad more or less blanks in between
you can then put al the pieces on top of each other as you wish and in between some kind of rubbery substance like kit (or any substance that could acoustical decouple), now the pieces have an evan higher resonace frequency as when the thing was pored in one piece. if the rubbery substance does his work really really good you should end up with the resonacy frequency of one of the pieces wich is extremely high. (ofcourse this substance wont exsist)
this way you end up with something like the matrix (B&W)system as for resonances. i believe sonus faber uses something like this with there wooden cabinets, they use lots of layers on top of each other to form te cabinet with some kind of stuf in between.
the rubbery stuf in between has to decouple the vibrations between the pieces.
Phoeee well thats out, im walking around with this idea for over 2 years now, maybe ill gone do some poring tomorow to look if i can make small walls of concrete, because if the technic works you dont need concrete contraptions of 400 kilo.
tell me what you guys think.
its like a floorstanding speaker but then cut vertical in piecs like 10 cm only the piece where the driver is,is of one piece ofcource.
so you have a bottom a top ,a piece with the driver, and a piece blank with no holes just to add volume to the enclosure.
now you can arrange then as you wish also you can increase and decrease the internal volume so you can make monitors with the same molds as well as floorstanders just ad more or less blanks in between
you can then put al the pieces on top of each other as you wish and in between some kind of rubbery substance like kit (or any substance that could acoustical decouple), now the pieces have an evan higher resonace frequency as when the thing was pored in one piece. if the rubbery substance does his work really really good you should end up with the resonacy frequency of one of the pieces wich is extremely high. (ofcourse this substance wont exsist)
this way you end up with something like the matrix (B&W)system as for resonances. i believe sonus faber uses something like this with there wooden cabinets, they use lots of layers on top of each other to form te cabinet with some kind of stuf in between.
the rubbery stuf in between has to decouple the vibrations between the pieces.
Phoeee well thats out, im walking around with this idea for over 2 years now, maybe ill gone do some poring tomorow to look if i can make small walls of concrete, because if the technic works you dont need concrete contraptions of 400 kilo.
tell me what you guys think.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.