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My attempt to repair Phase tech pc8.5s

jwxr7

jwxr7

Active Member
I've been talk back and forth with my older brother about a set of phase techs he's had sitting idle for a while..P1000859.jpg

He brought them over last weekend for me to play with. We'll probably do some kind of trade for them.

I knew that at least one of the woofers needed refoamed and at least one crossover may have issues P1000864.jpg

So I started this thread to show what I'm dealing with, and if anyone with experience with this type of speaker can add some helpful advice, that would be great too.
 
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I pulled to woofer with the obviouse foam problem. View attachment 134923 I started removing the old foam and the layer of bad covering over the piston. f2.jpgf3.jpg The other woofer looks like it may have been refoamed at some point. It's like new foam, but the area where it's glue to the piston is questionable. Maybe the one with bad foam was always in the sun.

I have some Madisound 10" woofers (one on left) that I could default to if the refoam goes bad and I don't want to spend $95 each for new PT woofers. The old PT woofer on the right.
View attachment 134928View attachment 134929
 
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I was testing the mids and highs and the tweeters sounded like they were getting lower frequencies. It's probably the crossovers. So I pulled all the crossovers to test and inspect the components. View attachment 134960

The woofer ones are fine but both mid/high crossovers had bad capacitors and resistors.

I am concerned that the tweeters may have been damaged also. I removed the foam stuff and then the tweeters t3.jpg
.View attachment 134959
I'm having a co-worker test the tweeter's responses and see if they are okay and still matched.

I found the parts I need for the Xovers @ parts express, I need to see if they have a refoam kit that might work with the woofers.

I'm going to listen to the mids later today and see if they need attention.
 
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The mids still sound great :thmbsp:!

The company still sells tweeters too, for around $45 each. Hopefully the original tweets are fine, I may find out later today. I don't want to invest large sums of $$ on this project.
 
I'll be watching this closely, I have a pair of PC-60's that need re-foam. They are the 2 way, with a 5 inch (or so) Styrofoam woofer and very nice dome tweeter. Very impressive build, I'm expecting good things once done. I also have to find a correct set of surrounds, the "generics" I have won't fit. Have you decided what glue to use on the "cones"?
 
Have you decided what glue to use on the "cones"?
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Not yet, I do have concerns about bonding to the styrofoam. Whatever they used originally looks black and it holds real well. I still need to get that and a thin layer of surround off mine.
 
jwxr7 said:
Not yet, I do have concerns about bonding to the styrofoam. Whatever they used originally looks black and it holds real well. I still need to get that and a thin layer of surround off mine.
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Mine too, it looks like a silicone adhesive. When I do these, I will run tests on some Styrofoam scrap first, the wrong chemical and the foam could turn to "mush" in seconds!
 
One refoam seller recommends using the white latex glue vs contact cement for styrofoam. It has also been said that passive radiator replacement plates could fix the whole front and surround at once. .10 passive IMG_2493 (1).jpg They say It's just quite hard the keep the VC aligned with that fix though.
 
himm37 said:
I'll be watching this closely, I have a pair of PC-60's that need re-foam. They are the 2 way, with a 5 inch (or so) Styrofoam woofer and very nice dome tweeter. Very impressive build, I'm expecting good things once done. I also have to find a correct set of surrounds, the "generics" I have won't fit. Have you decided what glue to use on the "cones"?
Click to expand...

When you find a source for the surrounds please let us know. I've got four PC-60s I would like to get back up and going. Two I bought new back in the day and two more I bought on the *bay when my original foams started going. The second set extended the PhaseTech goodness only about another year.

I did manage to refoam the pc-50 passive subs. If I recall correctly i had to splice a slightly larger surround. Man, it's ugly as all get out but it works. I would like to re-spray some kind of material on the face of the flat styrofoam cone to get back that softness but not sure what to us and worry about melting the whole thing by mistake.

I did talk to the phase tech office in florida about parts but they would only replace the whole driver. For the money they wanted I can find a nicer set of vintage with readily available surrounds if needed.
 
jwxr7 said:
One refoam seller recommends using the white latex glue vs contact cement for styrofoam.
Click to expand...

Thats what I used. Eileens I think it was. I worked but test it out first for sure.

jwxr7 said:
It has also been said that passive radiator replacement plates could fix the whole front and surround at once.
Click to expand...

hadn't thought of that :scratch2: wonder if there's one of appropriate size for the PC-60?
 
cubby01 said:
I did manage to refoam the pc-50 passive subs. If I recall correctly i had to splice a slightly larger surround. Man, it's ugly as all get out but it works. I would like to re-spray some kind of material on the face of the flat styrofoam cone to get back that softness but not sure what to us and worry about melting the whole thing by mistake.
Click to expand...
How did you get all the old foam and adhesive off the piston when you refoamed? I'm having trouble getting it off mine without getting small chunks of styrofoam with it.P1000888.jpg
 
well, I figure it out. I used an exacto knife and careful pulling action. Then I used my rotary tool with a plastic brush on the styrofoam, and a wire brush on the basket. View attachment 136330

The other woofer has definitely been refoamed before. I started pulling that one apart. foam.jpg the center covering came apart alote easier than the first.
 
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My co-worker gave me the results of the tweeter tests he did for me. He said tweeter #1 had an excellent response but #2 didn't match well. There were anomolies around 12khz and 14khz. These tests were done out of the original baffles, so we will try again after I fix the crossovers and reinstall them. I may end up buying a replacement tweeter for #2 though.
 
I'll be following this as well....I have a pair of PC 8.5s that I picked up for very little, but they need foam. I'm debating on whether to have them redon locally (there's a speaker tech in Chicago that used to sell phase tech) or buy the drivers, or just get rid of them as I have a lot of other speakers. I'll probably fet them refoamed locally. Doing them myself, with the strange piston drivers and lack of foams, seems to be more fuss than it's worth. I hear they're nice speakers once fully functional.
 
Hey JohnVF, Is there enough foam left for you to measure the roll size of the surround? I regret not getting a good measure of this on the original foam and I want to try getting the same as OEM.
 
I refurbed a set of pc6.5's and a matching sub last year. These are a very nice line of speakers. I ended up spending a a little over a hundred to get the replacement drivers from phase tech. I recapped with Daytons. It was a challenge fitting film caps in that little box. Anyway, I am very happy with them.
 
I recieved my crossover parts yesterday and finished reassembling them last night. View attachment 136671 I replaced all the bad components and upgraded a few other caps along the way.

I also noticed that the best testing tweeter has a 1997 date on it, the other is original with a 1990 date. So it has had a tweeter issue in the past. I wonder if the 7 year difference is why they aren't similar (within a normal range, acording to my co-worker)?

I put the crossovers in and reinstalled the tweeters and their foams. I used the Madisound woofers just for testing purposes, so the mids and highs weren't alone. I only listened for a few minutes before bed and was impressed. They sound very good fed by my Marantz 2235b playing FM radio. I will try some cds to give the mids and highs a better test later.
 
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I haven't pulled the foam surrounds off the second woofer yet. I did notice the surround looks like a much better size fit than any I can find with a flat inner flange, but it kinda looks like they used angled foam on a flat piston. That's could be why the foam didn't stay glued down well on the piston. That is possible because I have found angled foam with the perfect dimensions. It's been suggested by a foam seller that I try gluing angled foam to the back of the piston too. I'm not sure how well things will stay aligned as far as the woofer's normal excursion parking place. All the flat style foams I've found have dimensions that limit the amount of flange overlap on the piston and/or basket.
 
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