Polydome cleaning.
- Thread starter 7.62
- Start date
I just treated a single voice coil 5 inch midrange with non silicone brake fluid.
Turns out I have 18 of them, picked one that the dust cap had been pushed in and I had pulled it out with a vacuum and straw but it's still not perfect.
I'll check it every so often to see how it responds.
I only treated the outside of the surround, don't know if Bill treated just one side or both (or maybe it will penetrate through to the inside?). Maybe I'll pull one of the dvc 5" out of my Infintesimals when I have some free time and see if both sides are treated.
Turns out I have 18 of them, picked one that the dust cap had been pushed in and I had pulled it out with a vacuum and straw but it's still not perfect.
I'll check it every so often to see how it responds.
I only treated the outside of the surround, don't know if Bill treated just one side or both (or maybe it will penetrate through to the inside?). Maybe I'll pull one of the dvc 5" out of my Infintesimals when I have some free time and see if both sides are treated.
Hmmmmmm
Just checked the 5" midrange that I treated last Sunday.
While the rubber surround looks a *little better* than the two non treated ones, it's pretty dry.
While it doesn't appear to have harmed the surround, results were not as expected.
Doesn't look anything like the 5" Watkins mid/woofs that Millersound repaired and treated just over a year ago WHICH ARE STILL SHINY AND SLICK LOOKING. The front of the basket (metal) must have been treated too as it is still shiny and slick looking
Maybe it's not the same chemical product though I did use DOT3 brake fluid which is supposed to be a non silicone brake fluid.
Just applied another coat, will check again in a week or so.
Just checked the 5" midrange that I treated last Sunday.
While the rubber surround looks a *little better* than the two non treated ones, it's pretty dry.
While it doesn't appear to have harmed the surround, results were not as expected.
Doesn't look anything like the 5" Watkins mid/woofs that Millersound repaired and treated just over a year ago WHICH ARE STILL SHINY AND SLICK LOOKING. The front of the basket (metal) must have been treated too as it is still shiny and slick looking
Maybe it's not the same chemical product though I did use DOT3 brake fluid which is supposed to be a non silicone brake fluid.
Just applied another coat, will check again in a week or so.
slimpikkins
Super Member
I don't think I'd put brake fluid on anything...just sayn.
slimpikkins
Super Member
There have been threads in the past in the speaker furom about rubber surround care. Most seem to use similar products as mentioned here. If you are a customer of theirs you could just email Millersound and ask about rubber surrounds.. I'm sure they would give you a straight up answer.
uvafan420
LiKe It LoUd
Going back to the question of what are they made of. I watched that quite old Infinity produced video on youtube (the one with Arnie in and describing the companies history etc...), and that video called the material Polypropylene. And obviously a very very thin mold of that material, as it is usually stiff. I do know manufacturers, of packing tapes, who have film lines that melt Polypropylene pellets into an extruder and blow the material up into a bubble to make it really thin, so know it can also be made to be playable as well. Just depends on the process. The thickness that Infinity made the dome is listed in a thread here somewhere, and also on a foreign website I ran into some time ago. But to recreate a replacement for them, it really would be the only way to go, as any other material will change the sound characteristics.
swechsler
Frog Whisperer
Are they really the same formulation? Even allowing for differences in thickness, the polydomes feel almost like rubber vs the stiff plastic of a can lid.
okeeteekid
Well-Known Member
I have doubts that it is Polypropylene because if it was it wouldn't deteriorate like it does, the polygraph is poly and it don't deteriorate, the material almost looks like a soft vinyl or urethane, someone should ask Paul McGowan if he could find out from his friend Arnie Nudell what they were made ofGoing back to the question of what are they made of. I watched that quite old Infinity produced video on youtube (the one with Arnie in and describing the companies history etc...), and that video called the material Polypropylene. And obviously a very very thin mold of that material, as it is usually stiff. I do know manufacturers, of packing tapes, who have film lines that melt Polypropylene pellets into an extruder and blow the material up into a bubble to make it really thin, so know it can also be made to be playable as well. Just depends on the process. The thickness that Infinity made the dome is listed in a thread here somewhere, and also on a foreign website I ran into some time ago. But to recreate a replacement for them, it really would be the only way to go, as any other material will change the sound characteristics.
uvafan420
LiKe It LoUd
Just going on what Infinity said in their video. Here at 11:30
uvafan420
LiKe It LoUd
There is many forms of polypropylene from what I have been reading up on. Elastomeric Polypropylene, etc... As I was saying in the earlier post, it just depends on your process. I think for Infinity to call it a Polydome, some form of polypropylene would have been used (my opinion). This site describes how polypropylene can be made rubbery. http://pslc.ws/macrog/pp.htm
This quote from another website also explains that polypropylene can be made pliable/rubbery.
- "Newer versions contain an elastic element to them. This gives them a rubber-like composition and opens the door for new uses."
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Done and done, same as what RussHuns said.
I was reluctant to contact them because I hate "bugging" or "bothering" people. It's just a quirk I have.
There were a couple caveats, must be non silicone and do not get on painted surfaces as it can damage paint.
I noticed today, a few days after applying the 2nd coat, the rubber surround was a lot more shiny than the first coat was after a week.
Plenty of internet info on non silicone brake fluids (DOT3 and 4 and possibly DOT 5.1) DOT 5 is silicone base and should not be used for that reason. One often asked question found-- is "conventional" fluid different from "synthetic" fluid, it appears it is all the same.
UPDATE 11-21-2017 -- have applied three coats of non silicone brake fluid to the volunteer 5" midrange rubber surround, last coat was around 4 days ago. While shinier/slicker than an untreated mid it's still not as shiny as the ones Millersound treated.
One BIG difference, the midrange surround I have treated is WAY more soft/flexible than the non treated midranges I have.
When lightly pushing on the cone it is very apparent the treated surround moves easier than the untreated ones.
So I wonder, how does this compare to the original flex of circa 1981 newly produced mids.
I suppose there is no way of knowing as all OEM mids are now 35+/- years old.
Trying to decide whether or not to treat the 6 mids in my RS II's.
Maybe I'll treat a couple more spares and then put those three in one of my RS II's and see if there is an audible difference in sound or performance.
UPDATE 11-22-2017
After seeing how much softer and more flexible the treated volunteer surround is, and having a long holiday weekend, did a first coat on the 6 RS II mids today.
As mentioned, brake fluid will do bad things to paint, caution should be used when applying it.
Did not want to dribble any on the brown crackle finish or on the I assume painted EMIT face plate.
I used a small artist brush to get the fluid into the creases on the inner and outer edges of the surround (while it can be done with a cloth the small brush works much better) and then soft cloth to wipe fluid on the roll itself. Wiped excess off the poly cone with *don't laugh* TP. Softer than paper towel or napkin and quite absorbent.
I'll do 1 or 2 more coats (after 3 on the volunteer mid the results were very apparent) over the weekend.
Wondering if any audible changes will be heard (if any, better I hope) or if the volume control will show more volume at a lower setting (doubtful but who knows).
Obviously both will be subjective judgements on my part.
UPDATE 6-24-18 The 5" midranges I treated with brake fluid went back to dull flat rubber long ago.
The ones in my Infinitesimals that Millersound treated long ago are still shiny and slick....
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slimpikkins
Super Member
^^^thanks for that info.
7.62
Infinity nutcase.
That clip is great in so many ways, It really makes we wonder. Why did they invent the first Class D switching amplifier?
In a round about way did they know it would provide the power needed to properly play the brand?
I have not seen the 8.1's since a day or so after I posted those photo's. I made some room in my office closet and put them away until I get my audio room going. I'll pull them for a few pics to see how the treatment is lasting this weekend and post them.
The other two polydomes I have, one still has the majority of material left. I think I'll mike it and post the thickness here. I wonder though if a portion could be sent to a lab and be analayized for it's content. Anyone have any suggestion's on that ? as to where to send it, I'll do some looking this weekend.
update, i sent a request to a company called Intertek for a material analysis.
In a round about way did they know it would provide the power needed to properly play the brand?
I have not seen the 8.1's since a day or so after I posted those photo's. I made some room in my office closet and put them away until I get my audio room going. I'll pull them for a few pics to see how the treatment is lasting this weekend and post them.
The other two polydomes I have, one still has the majority of material left. I think I'll mike it and post the thickness here. I wonder though if a portion could be sent to a lab and be analayized for it's content. Anyone have any suggestion's on that ? as to where to send it, I'll do some looking this weekend.
update, i sent a request to a company called Intertek for a material analysis.
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Thanks for nudging me into action.
GregDunn
Active Member
John Ulrick designed Infinity's first Class D amp in the early 1970s. I'm sure the media person who assembled the video was unaware that the first Class D audio amp was designed by Clive Sinclair and Gordon Edge in about 1964 for Sinclair Audionics.
Maybe Infinity's was the first real high fidelity high power Class D....
