Blown woofers

[braid11]

Is there a way to test if the crossovers are OK, with a good multimeter?

[2fastdriving]

You're going to have to talk to your dealer and/or Wilson and get them fixed. I wouldn't mess with it, and the crossover is indeed potted and can't be serviced.

[Charles]

I believe the Mac autoformer protects speakers from DC, which is very damaging to every speaker component. Something to think about. Any amp is subject to catastrophic failure. The older the amp the more likely it is to fail: you have a very expensive heavy speaker. Your pride and joy, only to find it destroyed and the possibility of a house fire. Speaker fuses are of little help from heavy raw DC from a powerful amp.

[TLi]

It is of course very easy to say but would be difficult to implement, is it time to change the speakers and amp?

Even if you managed to change the woofers and checked the crossovers, you have a burn-in left channel and a hybrid right one with old midrange / tweeter and new woofers. How they can sing in harmony is out of my sense.

As Charles has mentioned, if you have expensive speakers, it is too risky to run really old amps on them. Isn't it time for a new amp?

[Charles]

Originally Posted by TLi

It is of course very easy to say but would be difficult to implement, is it time to change the speakers and amp?

Even if you managed to change the woofers and checked the crossovers, you have a burn-in left channel and a hybrid right one with old midrange / tweeter and new woofers. How they can sing in harmony is out of my sense.

As Charles has mentioned, if you have expensive speakers, it is too risky to run really old amps on them. Isn't it time for a new amp?

I believe the reason you have such a viable market for vintage Mac amps (both tube and solid state) is that in the case of catastrophic amp failure the DC is shunted into the autoformer and the speaker is left unharmed. The older the direct coupled amp the more likely it is to fail and blast the speaker with raw DC. I also believe that class A amps, since they run so much hotter, as they age are more likely to experience this type failure. I would never leave a class A amp running all the time 24/7.

[Formerly YB-2]

Originally Posted by braid11

Is there a way to test if the crossovers are OK, with a good multimeter?

Not really. X-overs are mostly reactive components (chokes & caps) which are beyond the ability of a DVM to analyze. Wilson are likely one of the most un-DIY speakers out there.

Good advice on amps in several of the previous posts.

Good luck with all.

[CGabriel]

Originally Posted by braid11

Is there a way to test if the crossovers are OK, with a good multimeter?

You cannot check them with a multimeter. You would need an impedance analyzer (not in everyone's toolbox) and would have to check each output of the crossover. And you have to know what the expected reading should be. And you would need to know "how" to use an impedance analyzer.

The good news is that the crossover is "probably" not damaged. If it was the most likely failure would be a coil or soldered connection given the heat generated to melt the speaker voice coil.

A speaker of this quality and precision deserves to be serviced and checked by the experts that created it. If you go DIY and it doesn't go well the cost will exceed any cost to send it to Wilson. Bite the bullet - I know it's painful - but necessary in this case.

[Rilands]

Sasha's haven't been around that long. Are they not still in warranty.

Sonus Faber replaced mine after 4 years free of charge. I replaced them myself, there was nothing to it. However the damage was not my fault. Maybe this isn't yours.

[braid11]

Well, I was away for a while. Thanks for all the input.

The good news is that the crossover is fine. I wanted to test the speaker by hooking it up to a good amp, but was concerned it was a dead short. So I measured the resistance/ohms of both speakers.

The good speaker reads 2.6 ohms on the speaker terminals. The one with the blown woofer read 2.6 ohms, so it was not a dead short.

I hooked up a spare amp, and the bad speaker played music just fine through the Watt module = tweeter/midwoofer. In fact, I played some deep bass music, and the blown woofers play bass.

I removed the top bass woofer, see the pics: it's a Scanspeak 18w85??. Looks like maybe 21w8535-01. I think I read they are modified to Wilson specs.

The woofer is installed like most: the wire from the crossover is soldered to the speaker terminals. The woofer is screwed VERY VERY tightly to the baffle. I wonder if they use stretch fasteners, usable once. Replacing the woofers just requires the new drivers, maybe new fasteners, and an excellent solder job.

I'm not concerned with having new woofers with an "old" speaker. If they are from Wilson, they will be perfect Sasha 8" bass drivers. Once properly installed and run in, there is no reason the speaker will not sound as good as it was. There is no reason to replace the whole thing.

Still, looking at the pics makes me feel a bit sick.

BTW, I run the Plinius SA-250 in class A/B mode, not class A. Class A does make the amp run SUPER hot. It is switchable. The Plinius dealer says it's fine to run it 24/7 in A/B mode. Plinius is going to fully service and repair the amp.

The ARC preamp tubes are failing: snap, crackle, pop. That started the very night this happened, when I first powered up the system. I wonder if that contributed to this.

Tom

[braid11]

Originally Posted by Rilands

Sasha's haven't been around that long. Are they not still in warranty.

Sonus Faber replaced mine after 4 years free of charge. I replaced them myself, there was nothing to it. However the damage was not my fault. Maybe this isn't yours.

I did not buy them new. I've had them for about 2 years. I guess my dealer will let me know, but I doubt it.