So the stands are going to be unique. They needed to be adjusted vertically. I initially thought studs mounted to each side of each speaker, then cutting out slots in the stands. But this was too restrictive...
In the end I chose 1/4"x6" bar stock stainless 6ft tall x4. 2 per side.
Then 32 neodymium magnets, 2 per enclosure. This will allow great flexibility, although at 1 helluva cost.
In the end I chose 1/4"x6" bar stock stainless 6ft tall x4. 2 per side.
Then 32 neodymium magnets, 2 per enclosure. This will allow great flexibility, although at 1 helluva cost.
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Terrible explanation in my previous post, sorry. I just envision each speaker (5lbs) in between columns of steel and 2 N52 magnets on both sides of each speaker so they can slide and be positioned wherever the user desires within a 6" horizontal as the columns of steel are 1/4" x 7' beams @ 6" wide.
Today I got in the (Qty=32) 1"x.5" N52 Neodymium magnets. Measured them right @ .999" with a micrometer. Very tricky with that N52 Neodymium!...
Now I have 2 tools to drill the holes for the magnets. The one on the left, a 1" hole saw drilled a hole approaching 1.030". Not good. Then I used the spade 1" bit on the right. It produced a much tighter tolerance. I measured near 1.009", but still not tight enough for an extreme magnet. I was hoping to press fit it into the wood.
Today I got in the (Qty=32) 1"x.5" N52 Neodymium magnets. Measured them right @ .999" with a micrometer. Very tricky with that N52 Neodymium!...
Now I have 2 tools to drill the holes for the magnets. The one on the left, a 1" hole saw drilled a hole approaching 1.030". Not good. Then I used the spade 1" bit on the right. It produced a much tighter tolerance. I measured near 1.009", but still not tight enough for an extreme magnet. I was hoping to press fit it into the wood.
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I used much smaller magnets to mount grills before. The magnets will still work well through a small amount of wood or filler so they are not visible. You will need to glue them in with epoxy or something similar unless you mount them blind from the inside as the force of moving the metal will pull them out of the those holes no matter how tight they are.
Try a forstner bit and drill press for drilling in MDF - will give you a much cleaner and more precise hole, and a dab of white glue, or if really concerned - as fluid notes epoxy- will guarantee the pieces to never come loose. Of course, be very wary of maintaining polarities - I've seen many neos come with a small telltale paint dot to help with that.
Here in the states we have something called gorilla glue. It's a bubbling mess when it starts to dry but extremely strong I've found in other projects, so that's what's I'll be using with the 1" spade bit.
Tomorrow the 1/4" thick 6" wide 7' tall bars come in. 35lbs each.
4 bars have been ordered, but I'm really hoping I can get away with 1 bar and 1 magnet per 5lb+ box. Otherwise, each stand will approach 100lbs.
Will report back tomorrow. I don't expect too much flex from the 1/4" bar stock, but I do have reinforcements ready to weld in JIC.
Tomorrow the 1/4" thick 6" wide 7' tall bars come in. 35lbs each.
4 bars have been ordered, but I'm really hoping I can get away with 1 bar and 1 magnet per 5lb+ box. Otherwise, each stand will approach 100lbs.
Will report back tomorrow. I don't expect too much flex from the 1/4" bar stock, but I do have reinforcements ready to weld in JIC.
The metal came in. It is just abit flimsier than I thought, so the side supports will have to be welded onto the main structure. The great news is that just one of the magnets can support close to 13lbs. So just one 7' bar per side is going to work. While very impressive, the pull effect of the magnet on direct contact with the steel is very 'potentially' dangerous not to mention while sliding the magnet on the surface of the steel, it gets scuffed pretty bad. So...
I had some .070" thick teflon sheet laying around from a previous project and put it in between the mag and the steel. It could barely support 5lbs, but the extreme magnetism + ability to slide is making me look more closely at a plastic type of isolator sheet with an appropriate thickness to support the weight of each speaker. Teflon is very expensive tho, but it can also take a hit without cracking... Any ideas for other isolator candidates besides teflon?
Here is the heavy metal for 1 stand: 13lb+13lb+13lb+36lb=75lb
I had some .070" thick teflon sheet laying around from a previous project and put it in between the mag and the steel. It could barely support 5lbs, but the extreme magnetism + ability to slide is making me look more closely at a plastic type of isolator sheet with an appropriate thickness to support the weight of each speaker. Teflon is very expensive tho, but it can also take a hit without cracking... Any ideas for other isolator candidates besides teflon?
Here is the heavy metal for 1 stand: 13lb+13lb+13lb+36lb=75lb
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I clculate a bit over 6 litre. To get a vent the size you spec i have tio tune really high and there is a large bump in response at the bottom (~10 dB). Tuning it much lower i get a calulted vent of 5cm D (~2") x 36 cm long, and F6 ~50 Hz, F10 40 Hz.
dave
Dave, can I pick your brain? Tomorrow I start construction/modification of current 8 boxes to make 16, 8 per side. The internal measurements will be 6"x4.5"x10". I was thinking sealed. Can you tell me what you see? or even better, what you would recommend?
EDIT: Acoording to Madisound for a .15cu.ft. sealed box, the F3 is 100Hz and F6 is 77Hz.
EDIT: Acoording to Madisound for a .15cu.ft. sealed box, the F3 is 100Hz and F6 is 77Hz.
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I never did get around to modifying the current 8 boxes yet. Currently, they are all effectively sealed as I stuffed the vents with rags and have been very pleased with the sound.
What I have been working on are the 7ft x 6" x 1/4" steel stands. Yesterday, I welded the 6.5ft x 2" x 1/4" supports. That was some work on a 110V welder. It did not penetrate well. And the warping of the metal was unexpected... Well obviously I'm not an experienced metal worker, but I do have resources at work to weld 16 gauge steel. Maybe I should have stuck with that thickness!
But the 1" x 1/2" neodymium magnets I've chosen are over-the-top powerful, and can easily support at least 20lbs PER magnet when exposed to the bare A36 steel beam. The magnet is rated at 70lbs pull force.
Today, I was working on the base...
Some pics soon...
What I have been working on are the 7ft x 6" x 1/4" steel stands. Yesterday, I welded the 6.5ft x 2" x 1/4" supports. That was some work on a 110V welder. It did not penetrate well. And the warping of the metal was unexpected... Well obviously I'm not an experienced metal worker, but I do have resources at work to weld 16 gauge steel. Maybe I should have stuck with that thickness!
But the 1" x 1/2" neodymium magnets I've chosen are over-the-top powerful, and can easily support at least 20lbs PER magnet when exposed to the bare A36 steel beam. The magnet is rated at 70lbs pull force.
Today, I was working on the base...
Some pics soon...
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I'm reminded of the movie, 2001: A Space Odyssey when I see the speaker stands. The Monolith. Was not my original plan, just happened that way.
If you look close you can see the bow, due to the heating of the metal. The pic of the weld will be towards the rear of the listener. That nasty won't be visable. Definately need 220V welder for heavy duty work...
If you look close you can see the bow, due to the heating of the metal. The pic of the weld will be towards the rear of the listener. That nasty won't be visable. Definately need 220V welder for heavy duty work...
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Yes. Next pic will be 8 P7's on 1 stand, with AMT in the middle, and 4 subs on the bottom. The subs will help with the balance as well. All .15cu.ft. 5lb boxes will be attached to the stand by the magnets.
The stands are weighing in @ 53lbs ea. I'm sorta worried about the stand transferring harmonics. After dropping 1, it sounded like it had a resonance between 1-7Khz.
Or maybe EQ lol. I've been listening to the system, for the past month, as it is with no EQ. I've tried to balance the P7's with a AMT super tweeter and a set of subwoofers. I'm starting to realize DSP is on the horizon with the addition of 4 more P7's per side and only 2 more 8" subs. So 8 P7's and 4 Subs per side. I was originally thinking miniDSP with class D amps, but am now leaning towards a DEQ2496 and keeping the Audiousource Amp 3's which are class A/B amps. Even though old school, I like them with their attention to detail on the power supply side with the toroid transformer when they first arrived on the market.
Update:
Initial build of all 8 of the SB23MFCL45-4 8" subwoofers are complete. 24mm p-p movement on these beasts. 150W ea.
Initial testing/listening with 2 per side in series powered by Audiosource Amp 3 was mediocre++. Not quite good enough IMO, so this is why another Audiosource Amp 3 will power 2 more per side, in series. There are volume adjustments on these amps.
Most likely the subs will be placed on the opposite sides of the stands so as to give more vertical placement area for the soon to come Pluvia 7 boxes, with magnets.
Initial build of all 8 of the SB23MFCL45-4 8" subwoofers are complete. 24mm p-p movement on these beasts. 150W ea.
Initial testing/listening with 2 per side in series powered by Audiosource Amp 3 was mediocre++. Not quite good enough IMO, so this is why another Audiosource Amp 3 will power 2 more per side, in series. There are volume adjustments on these amps.
Most likely the subs will be placed on the opposite sides of the stands so as to give more vertical placement area for the soon to come Pluvia 7 boxes, with magnets.
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In the above pic, you can almost see it. The .014" thick layer of polyurethane with adhesive backing on the metal tower. Here's a better pic, no flash. The N52 magnet is even more difficult to slide across this stuff, however I have rotation of the boxes to account for as well so I'll need the additional friction.
I hope to have the first 2 Pluvia "Mag" boxes done by this weekend for an initial listening test on these stands.
Cheers!
I hope to have the first 2 Pluvia "Mag" boxes done by this weekend for an initial listening test on these stands.
Cheers!
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