Phase Technology PC-60 crossover recap

Justgotohm

Super Member
Thought I would share this for any current or future Phase Tech PC60 owners.
Capacitors on stock board = capacitors I used.
5uf = 4uf + 1uf Dayton Poly 1%
2uf, 8uf = 10uf Dayton Poly 5%
.1uf = .1uf Dayton Poly 1%
.056 x 2 = .01 Vishay MKP 1837’s
75uf = I tested these out of circuit, they tested within 3% so I left these. To be honest I used whatever caps I currently had in my stash o caps. Pre planned I would have ordered the 75uf and as close to the .056 as I could find. I assumed the .056 are just bipass caps so the Vishays would work fine.
Here’s the thing, before recap the speakers had a lot of lowend for the size, pretty impressive, the mids and highs were good but slightly veiled. After installing all of the above the highs really came alive, vocals are much much better, lots more detail. The lows now seemed muted, before I could have lived without a sub, after you need a sub to keep up. There is really quite a difference. This maybe from a much lower ESR using these particular caps, the slight difference in the bipass cap values? I should have swapped out the 75uf ? I can say this, while the speakers opened up I could have lived with them much easier before the new caps went in. Stock components think little Dynaco A25’s, new caps installed think little Klipsch Heresy’s, both speakers I like for different reasons.
B62E7FD6-4B00-46F0-9F75-5E3812C0D901.jpeg 063C9D2A-1A9D-402E-8A72-4A3B1EA25E30.jpeg C77763CC-C60C-4FAE-8D55-710463611460.jpeg 0149AD3E-A595-479D-AE12-9CFAF4116180.jpeg BE044096-1C72-42A0-9253-0F2DAC5B54C3.jpeg 0749D651-7906-41BE-B7E5-949CE90A0DBC.jpeg
 
Your pics are after recapping, correct? Were the originals all films except for the 75 uf, or were there some other NPE's in there?

Did you get them sealed up as well as they were originally?

Are you 100% sure that driver connections are all as they were (nothing reversed)?

I've never seen a 0.056 cap in a speaker, that's tiny!
 
The pic with the yellow MKP’s and blue electro cap are the original components. The pic below it with the black Dayton polys, black tape over the coil leads, and Vishays are after recap.
I am always really good at marking the wire leads as you can see in the cabinets and taking the time to make sure everything is sealed up as it should.
I’m assuming the little .056’s used originally were bipass caps which is why I used the Vishays for that purpose. They still sounded very good for the size just not as powerful as I felt they sounded before recapping them. The new owner is very happy with them so all is well. I posted this for anyone else looking for a parts listing or a basic understanding of what’s going on inside the PC60’s.
 
Woofer surrounds? Those can be replaced if you're handy at all. Much cheaper than finding a set of original drivers. These look like expensive speakers, I can't imagine what new woofers would cost.
 
The company still makes replacement drivers for all the versions of this speaker, as well as a current production model. The replacements run 80/each.
 
Thought I would share this for any current or future Phase Tech PC60 owners.
Capacitors on stock board = capacitors I used.
5uf = 4uf + 1uf Dayton Poly 1%
2uf, 8uf = 10uf Dayton Poly 5%
.1uf = .1uf Dayton Poly 1%
.056 x 2 = .01 Vishay MKP 1837’s
75uf = I tested these out of circuit, they tested within 3% so I left these. To be honest I used whatever caps I currently had in my stash o caps. Pre planned I would have ordered the 75uf and as close to the .056 as I could find. I assumed the .056 are just bipass caps so the Vishays would work fine.
Here’s the thing, before recap the speakers had a lot of lowend for the size, pretty impressive, the mids and highs were good but slightly veiled. After installing all of the above the highs really came alive, vocals are much much better, lots more detail. The lows now seemed muted, before I could have lived without a sub, after you need a sub to keep up. There is really quite a difference. This maybe from a much lower ESR using these particular caps, the slight difference in the bipass cap values? I should have swapped out the 75uf ? I can say this, while the speakers opened up I could have lived with them much easier before the new caps went in. Stock components think little Dynaco A25’s, new caps installed think little Klipsch Heresy’s, both speakers I like for different reasons.
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I have a pair of PC-60 II's sitting in the original boxes in storage. They are in storage because they sounded god awful right out the box new. I have tried them occasionally and pulled them out recently to try them on a new Marantz 30 amplifier. The same as before the highs are harsh and unruly compared to my Wharfedale 9.1's and there does not seem to be much sound in midrange. I wish I had read the Stereophile magazine article from 1984 that describes the same issues I have before I purchased them. In that article they said the speakers had a broad suck-out between 2khz and 10khz on models with a serial numbers 3801 and below. Mine are serial number 5881 and they have the same problem. The article speaks of being given a second pair with a revised crossover that were much better than the first pair tested. Currently they sound like a cheap pair of speakers from Walmart despite having a, what looks like, a high quality crossover and nice drivers. Bass response on the other hand is very good but in my opinion the speakers are unlistenable. I would love to find out what crossover changes were made to the second pair that made them sound so much better. As it sits, mine will remain the boxes
 
I have a pair of PC-60 II's sitting in the original boxes in storage. They are in storage because they sounded god awful right out the box new. I have tried them occasionally and pulled them out recently to try them on a new Marantz 30 amplifier. The same as before the highs are harsh and unruly compared to my Wharfedale 9.1's and there does not seem to be much sound in midrange. I wish I had read the Stereophile magazine article from 1984 that describes the same issues I have before I purchased them. In that article they said the speakers had a broad suck-out between 2khz and 10khz on models with a serial numbers 3801 and below. Mine are serial number 5881 and they have the same problem. The article speaks of being given a second pair with a revised crossover that were much better than the first pair tested. Currently they sound like a cheap pair of speakers from Walmart despite having a, what looks like, a high quality crossover and nice drivers. Bass response on the other hand is very good but in my opinion the speakers are unlistenable. I would love to find out what crossover changes were made to the second pair that made them sound so much better. As it sits, mine will remain the boxes

I have a pair model number 34,327 & 8.

if you remove your crossovers and take a photo, I can compare them to mine, which I think sound amazing. As best as I can recal, my crossovers where identical to the ones in the OP's photo's, but I did not expieriance any "bass dropoff" after a recap. I did go a different route with the .056 by pass caps, opting to use Audyn Cap Q4 0.01uF 400V MKP Metalized Polypropylene Foil Crossover caps instead. I also did replace the 75uf cap.
 
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I have a pair of PC-60 II's sitting in the original boxes in storage. They are in storage because they sounded god awful right out the box new. I have tried them occasionally and pulled them out recently to try them on a new Marantz 30 amplifier. The same as before the highs are harsh and unruly compared to my Wharfedale 9.1's and there does not seem to be much sound in midrange. I wish I had read the Stereophile magazine article from 1984 that describes the same issues I have before I purchased them. In that article they said the speakers had a broad suck-out between 2khz and 10khz on models with a serial numbers 3801 and below. Mine are serial number 5881 and they have the same problem. The article speaks of being given a second pair with a revised crossover that were much better than the first pair tested. Currently they sound like a cheap pair of speakers from Walmart despite having a, what looks like, a high quality crossover and nice drivers. Bass response on the other hand is very good but in my opinion the speakers are unlistenable. I would love to find out what crossover changes were made to the second pair that made them sound so much better. As it sits, mine will remain the boxes
I have a pair of PC60... the later version (approx 1987) which look just like the ones in the original post. You have the PC60 II which have a total different serial number count. So that serial number thing doesn't apply to yours. I have bought new woofers and changed the stuffing to Acousta-stuff (packed too tight at the moment) and they sound fantastic... amazingly so... the tweeter is exceptional and the mids are really coming alive as they break in. I do not understan why yours sound so bad... the tweeters on these are exceptional... I have had a few pairs of these... I am also a Paradigm, Wharfedale, Martin Logan, Goldenear, MoFi, and Focal dealer and these hold their own against some very nice speakers. I know yours are supposed to be a newer, improved model so I am at a loss as to what the problem could be, maybe remove the drivers and inspect the crossovers? they will be different than mine but maybe caps are leaking or something isn't wired properly?
 
Don't bother looking for used replacements, as you'll just end up with another almost impossible refoaming.

I bought new woofers for mine and am glad I did.
I bought a pair of PC60 speakers that someone had done a really nice job refoaming and the cabinets were in great shape. I had another pair that the cabinets were rough so I put those woofers in there and bought new woofers for the nice cabinets. Refoaming can be done, but it is difficult because of the way the cones are, definitely recommend buying new ones and these speakers are worth it. The new models are $1500 and I do hope there are improvements but properly set-up older models are amazing.
 
I got a pair of these with serial #s L 15714 and L 15513. Same back plate as the original poster. Are these the IIs or the original with good crossovers? I fired them up and they do not sound that good at all. I was expected greatness given all the rave reviews. I was thinking about plugging them into a DSP to bypass the passive crossover and eliminate it as a cause. Does anyone know the crossover point and configuration? I also noticed that both the negative and positive wires on the tweeter have continuity with the with the negative input. (same on both speakers) The woofer does not. Is that normal?

Here is a pic of the cross over from L 15513

IMG_3461.jpg
 
I got a pair of these with serial #s L 15714 and L 15513. Same back plate as the original poster. Are these the IIs or the original with good crossovers? I fired them up and they do not sound that good at all. I was expected greatness given all the rave reviews. I was thinking about plugging them into a DSP to bypass the passive crossover and eliminate it as a cause. Does anyone know the crossover point and configuration? I also noticed that both the negative and positive wires on the tweeter have continuity with the with the negative input. (same on both speakers) The woofer does not. Is that normal?

Here is a pic of the cross over from L 15513

View attachment 2988917
Both leads have continuity because there's an inductor between them.....
Looks like the original crossover. II should be marked.

I would start by recapping and replace those sandcast resistors too as they can degrade, and are cheap.
 
Yeah sorry I just learned how passive crossovers are wired and now understand my noob continuity question. Do you know the cross over point and roll off for this setup? Before blindly recapping I was going to just wire each speaker into my DSP to simulate the cross over. I guess I need to contact phase tech for that detailed information.
 
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