ShinOBIWAN said:
It should be better.. At least for the midbass enclosure, but likely for the mid-tweet as well in the configuration I mentioned (enclosure/compliant material/heavyweight slab/compliant material/enclosure).
You can get microsorb from Michael Percy (compeletly reliable if not always "prompt"). HOWEVER, you might want to try taking a roller pin (and some wax paper) to a sheet of blue tack (..not nearly as good - but somewhat similar to microsorb and better than sorbathane), just to try-out the concept at a fairly low-cost. (oh, and roll it thin.. close to 1mm.)
pg. 19
http://www.percyaudio.com/Catalog.pdf
google on the blue tack turned up:
http://www.dooyoo.co.uk/household-products/bostik-blu-tack/
Scott
Would something like this be preferable:
Where the red layer is microsorb and the green is dedshete panel.
Would something like this be preferable:
An externally hosted image should be here but it was not working when we last tested it.
Where the red layer is microsorb and the green is dedshete panel.
ShinOBIWAN said:Scott
Would something like this be preferable:
Where the red layer is microsorb and the green is dedshete panel.
Sorry its taken so long to respond..
(btw, nice illustration!)
Well then, this could be good or bad depending on the configuration and the drivers (generally)..
(..warning to all readers, there is a LOT of information here.. read it several times and hopefully it will become clear.. i.e. my powers of description can sometimes be described as an exercise in obfuscation.)
In your configuration (more specifically)..
For the mid-tweet "box" this would likely be a good idea in that it should provide a large degree of isolation from resonance created by the midbass "box", AND the motor and mass of each driver will likely NOT move back and forth (..what I described as "micro-rocking" in perceive 1).
For the midbass "box" it COULD be a good idea.. the problem here is that combating "micro-rocking" AND delayed cabinet energy from hitting the driver are at somewhat cross purposes. For instance, while we could be reducing delayed energy from the cabinets hitting the drivers with the proposed method in the illustration - you then have to consider how much the driver is allowed to "micro-rock" because of the compliant layer. (..*additonally you need to be concerned with how baffle energy is being isolated/stored to the baffle and hitting the drivers, as opposed to being transmitted through the rest of the enclosure - hopefully delayed and reduced in level.)
*Note that what I was orig. talking about was a method to sink midbass "box" energy by utilizing a "sink" on the top of this "box" under the mid-tweet "box" (..which would also provide a fair bit of isolation/decoupling to the mid-tweet "box").
IMO the best method, (if possible), is to have a very massive AND rigid BAFFLE that:
1B. Prevents "micro-rocking" by being VERY rigid at the interface between driver frame and baffle with ALSO enough weight to keep the baffle from moving, AND
2B. Transmits energy as quickly as possible to the cabinet.
Of course the problem here is #2 - i.e. what transmits energy away from the driver quicly usually transimts energy back to the driver quickly and at a greater level than otherwise might be the case with a material that is less "transmitive". Compound this problem with a cabinet that has modes that actually amplifys a portion of that transmitted energy in a specific band and the result could be an audible problem for that passband (..perhaps even altering freq. response).
So then, what we need is to have a CABINET that:
1C. Has little or no modes that would amplify vibrations, AND
2C. Actually dissapates (sinks) energy/vibrations transmitted from the baffle to it, so that energy that makes a "return trip" back to the baffle is both delayed and much lower in level.
So then, getting back to your loudspeaker, the "sink" I mentioned previously was to effect:
Part A (your midbass "box"):
1. Number 1B by adding weight to the speaker in general which will effect the baffle provided there isn't a compliant layer between the two (..as there IS in your illustration).
2. Number 1C by "sinking" spefic resonances that the top panel might have.
3. Number 2C (most importantly) by "sinking" overall cabinet energy, delaying the time and level of energy that will be transmitted back to the baffle.
Part B (your mid-tweet "box"):
1. Providing energy/vibration isolation between both "box's".
Thanks Scott,
I've just emailed MP Audio asking about ordering some of the microsorb.
I'm in agreement with you on the bass cabinet issue. I did mention in an earlier post that I tried decoupling it with the same method I used with mid/treble but removed the compliant foam layer since I though it blurred the sound a fraction, I think it will be the same case with the microsorb. Instead I think it would be best just to leave the dedshete in.
I plan on staying with the same plan for the mid/treble cabinet because the benefits are obvious to hear, maybe more so with the microsorb instead of the soft matting I'm using now.
I've just emailed MP Audio asking about ordering some of the microsorb.
I'm in agreement with you on the bass cabinet issue. I did mention in an earlier post that I tried decoupling it with the same method I used with mid/treble but removed the compliant foam layer since I though it blurred the sound a fraction, I think it will be the same case with the microsorb. Instead I think it would be best just to leave the dedshete in.
I plan on staying with the same plan for the mid/treble cabinet because the benefits are obvious to hear, maybe more so with the microsorb instead of the soft matting I'm using now.
ShinOBIWAN said:
IMO the single greatest mechanical improvement you could do would be:
For the Midbass "box":
1. Remove the dead sheet (and of course the compliant layer) and,
2. Form the midbass "box's" baffle (the segment that the driver attaches to as seen on the illustration) out of concrete (..with no sand).
I've found that this subjectively clears things up ( a lot actually) and seems to add another half+ octave of extension (..it doesn't of course - it just sounds like it does).
If you have any interest - just ask and I'll go into more detail on the forming of the baffle.
edit: Oh, and give MP (aka "the god of mod") quite a while from initial contact to receiving goods. Sometimes he is fast, sometimes he comes close to continental drift speed (..though never as bad as something like ordering custom transformers from tribute.nl). (..he is however completely reliable, at least I have no complaints nor have I ever heard of anyone complaining about him other than the occasional "speed" issue.)
ScottG said:
How would I go about forming a mold from the existing midbass baffles I already have?
I'd suggest plasticine and lots of petroleum jelly. Or you could cast a female mold from plaster.
ShinOBIWAN said:
I haven't ever done it like that before, rather I just made the mold from mdf and used silcone lubricant for the releasing agent. I think its do-able though, and probably pretty easy.
Here is a company the produces a pour-mold product:
http://www.smooth-on.com/concrt.htm
(I've actually looked them over before, but not for their mold but rather for their plastics as a polymer additive in concrete.)
You might try searching the web and your local concrete supplier.
When looking into the product, also look at releasing agents - specifically a releasing agent that won't harm your baffle, AND a releasing agent (*if neccesary) that won't leave a slippery/greasy surface on the concrete. ((*I say "if neccesary" here because I believe that there are actual mold liquids that don't require it for the concrete pour.. could be wrong though.)
You will need to create an open box to "house" the current baffle.
You will also need to create a suspension that keeps the current baffle off of the bottom of the box and the back of the baffle flush with the top of the box. (..likely just a supportive brace/stick that is screwed into the back of the baffle, and rests on the top edges of the box.)
Depending on the product used you may need a realeasing agent for the baffle, and possibly latter for the mold.
Said differently:
1. make an open box with a depth 2 1/2 times the depth of the baffle with interior dimensions 3 inches beyond the length and width of the baffle. The box should be screwed together so that it can be taken apart more easily to release the mold from it. I wouldn't worry about minor leaks from box joints.
2. make a brace thats at least 4 inches wide and with a length as wide (or wider) than boxes outer edges.
3. screw the brace to the back of the baffle
4. spray a releasing agent on the interior of the box and on the baffle's front and edges and on the portion of the brace that is likely to come in contact with the pour-in urethene. (..or just spray the entire brace and baffle.)
5. place the box on LEVEL surface with a plastic drop cloth under the box for any minor leaks.
6. place the baffle face down in the box with the brace suspending the back of the baffle flush with the top edges of the box.
7. mix (as directed) and pour the mold up to the top of the box (..but not over).
8. wait the appropriat time and unscrew the box to release the mold from it, then pull the baffle out of the mold.
Nice thing here is you only need one mold.
Oh.. Additionally..
If there is additional space (where you intended to place in deadsheet and/or a compliant layer) then you will need to add that "depth" on to the back of the baffle.
There is also the question of attaching the baffle to the "box".. you will have to describe how you are currently doing this.
If there is additional space (where you intended to place in deadsheet and/or a compliant layer) then you will need to add that "depth" on to the back of the baffle.
There is also the question of attaching the baffle to the "box".. you will have to describe how you are currently doing this.
ScottG said:
Ok thanks for the tips Scott.
Its looks relative painless (on face value at least).
About the attaching of the baffle:
An externally hosted image should be here but it was not working when we last tested it.
If you look at the photo here you'll see 6 holes in the driver recess on the baffle, in these sits a 100mm bolt thats recessed into the driver recess to allow the woofers to sit correctly and not foul the heads of the bolts.
I then simply tighten these up which clamps the baffle to the rest of the enclosure.
A few questions:
What's the quality of the finish like on the concrete, I'm primarily concerned with air cavities.
Is concrete easy to sand and shape if I do have minor or major imperfections?
I'll be painting these so how will this sit with the concrete, its obviously a somewhat porous surface but I'm primarily concerned that the paint may not take or will later come away from the surface after some time.
I really do like the look of the molding products you linked to in your post. I'm currently trying to track down something similar in the UK because the shipping for a few gallons will be prohibitively expensive. There's also talk of Hazmat on the website which could incure additional fee's too.
OK.. so then we have bolts IN the baffle? IF so, then it should be even easier to suspend them in the concrete as it forms (..though you'll need to make sure each are "up-right"/plumb).
Mine have ended-up every bit as good as mdf.. the key is not to have a greasy finish that silicone can add (that makes it difficult to paint). I tap the bottom sides of my box moulds and trowel/cream smooth the top layer of the open mould. Again, do NOT use sand in your mix.
Here is another link to read:
http://www.sculpt.com/technotes/concrete.htm
Its impossible to reshape (practically speaking).. IF for some reason you do have voids or negative spaces to fill then you can always use bondo or even wood filler. (..again make sure you don't have a greasy finish from crappy releasing agent.) Same applies for painting (i.e. no greasy finish).
I looked back at the link I provided - YOU COULD even "paint" the stuff on the baffle to get your mold.
FACTOID: Thiel Loudspeakers use to make their front baffles from concrete (again super smooth finish), the reason they stopped was shipping weight and exposure to damage during shipping.
Mine have ended-up every bit as good as mdf.. the key is not to have a greasy finish that silicone can add (that makes it difficult to paint). I tap the bottom sides of my box moulds and trowel/cream smooth the top layer of the open mould. Again, do NOT use sand in your mix.
Here is another link to read:
http://www.sculpt.com/technotes/concrete.htm
Its impossible to reshape (practically speaking).. IF for some reason you do have voids or negative spaces to fill then you can always use bondo or even wood filler. (..again make sure you don't have a greasy finish from crappy releasing agent.) Same applies for painting (i.e. no greasy finish).
I looked back at the link I provided - YOU COULD even "paint" the stuff on the baffle to get your mold.
FACTOID: Thiel Loudspeakers use to make their front baffles from concrete (again super smooth finish), the reason they stopped was shipping weight and exposure to damage during shipping.
Scott,
Found somewhere in the UK which deals in these sort of molding compounds you've highlighted.
http://www.tiranti.co.uk/indexhome.asp
However I'm confused as to which product I should be looking at. Could you take a look and maybe recommend one of those?
Found somewhere in the UK which deals in these sort of molding compounds you've highlighted.
http://www.tiranti.co.uk/indexhome.asp
However I'm confused as to which product I should be looking at. Could you take a look and maybe recommend one of those?
There's another here:
http://www.bentleychemicals.co.uk/prod_info_polyrubber.html
Quite a confusing amount of info and large product range but I believe these carry the 'Smooth-On' range that you linked to previously.
http://www.bentleychemicals.co.uk/prod_info_polyrubber.html
Quite a confusing amount of info and large product range but I believe these carry the 'Smooth-On' range that you linked to previously.
The first one would be the "Polyurethane Mould Rubber"
The second one is the Smooth-On distributor BUT they don't have VytaFlex specifically mentioned. After looking over the product listing it appears that the product history is (from old to new): PMC series, ReoFlex series, and then possibly the VytaFlex series. I say "possibly" the VytaFlex series here because it could well be that the ReoFlex IS the VytaFlex series (..problems with trademarks and all that). I'd contact the distributor on that one.
Additionally, the first link/source specfically mentions "releasing agent" and likely needs one for the concrete pour. The Smooth-On series however does NOT appear to need a releasing agent for the concrete pour (which is VERY good). (..i.e. find out about this.)
Personally I'd figure-out what kind of volume you'll need, (it won't be much), and then contact both sources to find out about pricing and releasing agent neccesity for the concrete pour. Also get pricing on releasing agent for both stages (i.e. mold stage and concrete stage if neccesary). Additionally make sure the concrete stage agent won't leave a greasy residue (..if its neccesary). If possible, I'd be willing to spend a bit more on a product that didn't require releasing agent for the concrete pour.
The second one is the Smooth-On distributor BUT they don't have VytaFlex specifically mentioned. After looking over the product listing it appears that the product history is (from old to new): PMC series, ReoFlex series, and then possibly the VytaFlex series. I say "possibly" the VytaFlex series here because it could well be that the ReoFlex IS the VytaFlex series (..problems with trademarks and all that). I'd contact the distributor on that one.
Additionally, the first link/source specfically mentions "releasing agent" and likely needs one for the concrete pour. The Smooth-On series however does NOT appear to need a releasing agent for the concrete pour (which is VERY good). (..i.e. find out about this.)
Personally I'd figure-out what kind of volume you'll need, (it won't be much), and then contact both sources to find out about pricing and releasing agent neccesity for the concrete pour. Also get pricing on releasing agent for both stages (i.e. mold stage and concrete stage if neccesary). Additionally make sure the concrete stage agent won't leave a greasy residue (..if its neccesary). If possible, I'd be willing to spend a bit more on a product that didn't require releasing agent for the concrete pour.
Progress on the replacement woofer enclosures are comming along nicely.
Had a lot of fun today doing my very first two-tone paint job, it came out better than I could have hoped for. I've got a very clean and definite line between the two colours, that 3M fineline tape really did its job - superb stuff.
It all looks somewhat rough because of the mega orange peel effect I've got going primarily thanks to using a ton of laquer. I find that the more you use the deeper the gloss and image. After its had time to harden I'll do the usual flatting and polishing.
Here's a few photos:
Had a lot of fun today doing my very first two-tone paint job, it came out better than I could have hoped for. I've got a very clean and definite line between the two colours, that 3M fineline tape really did its job - superb stuff.
It all looks somewhat rough because of the mega orange peel effect I've got going primarily thanks to using a ton of laquer. I find that the more you use the deeper the gloss and image. After its had time to harden I'll do the usual flatting and polishing.
Here's a few photos:
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.
An externally hosted image should be here but it was not working when we last tested it.
ScottG said:
Thanks Scott 🙂
Its nice to be moving forwards again. Only wish I had more time to spend on them, so I could get them done that bit faster but at this rate I should have them finished up in a few months tops.
I've also ordered some bits to have a go at creating a mold to cast the concrete woofer baffle. I had a long conversation with a chap from the company I listed earlier in this thread and it seems that the process is rather easy for the shape I described. He confirmed that I won't need a releasing agent with the Smooth-On stuff and he recommended a medium-hard shore rating molding compound. TBH I let him basically pick and choose what I needed based on my requirements, he seemed very knowledgable and I picked up a fair few good tips.
I'm looking forward to giving it a go next weekend.
ShinOBIWAN said:
Ah, Goooood. I thought the Smooth-On distributor might know his stuff.. (I find just the opposite at local retailers.. morons - well thats not fair, they are being paid a pitiful sum and thats what they are worth.)
Note about the concrete pour.. I've never done this myself, BUT you might want to try at least one casting with the agregate removed (sifted-out), and add in lead shot as a replacement. You know, a real heafty b@stard.
Also, before making the mold - look at the back-side of the midbass driver's frame. Chances are it isn't perfectly smooth/flat. IF possible you will want have an impression in your mold that is as close to the driver's frame (contact portion) as you can get - i.e. MAXIMUM contact area (devoid of voids). In my case I've used either wood for the mold (routed with a dremel) and/or "sculpted" some woodfiller (cleaned-up with a dremel). (it actually might be possible to use some sort of putty to press into the driver's frame - then release it and put it on your baffle.. don't know.) I suppose the other possbility to this is milling down the non-flat portion of the driver's frame, but I was to much of a wuss to try that. 😀
Oh.. and note that this is one of the few times you CAN alter the concrete baffle.. Say your mold wasn't quite perfect and the driver doesn't fit flush.. A dremel with a grinding attachment can smooth out imperfections to get the driver to fit properly. Note though that you need to be VERY delicate with this, otherwise you will "chip-out" the portion you are trying to correct. (..it is tough-to-impossible though if you get aggregate in this area - shouldn't be a problem though with lead.)
Ah.
Big problem:
ATC use this nasty, albeit very hefty cast frame. Can you spot the problem? 🙂
Big problem:
An externally hosted image should be here but it was not working when we last tested it.
ATC use this nasty, albeit very hefty cast frame. Can you spot the problem? 🙂
ShinOBIWAN said:
With one eye!
Actually I don't think its that big a problem. In fact I think the "putty" idea will work rather well.
Buy a small amount plasticine putty at a nearby craft store (..the kind you heat to make cr@ppy ceramics - NOT modeler's clay).
Fill in the driver's void's with the putty (perhaps using a small amout of "pam" for a releasing agent on the frame first) and then carefully peal them out.
Mark on your baffle where the putty impressions shoud go.
Finally, stick them on the baffle in the right spots.
Should do it.
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