Proac Ribbon Tweeters Damaged


Hi all - this is my first submission, so looking forward to your responses...

I own 2.5 year old Proac D48 R speakers, powered by a Parasound Halo A21 amp (about 8 years old). When listening the other day I thought the speakers sounded dull, muddy. It appears both of my ribbon tweeters have gone out and I am at a loss to understand why.  The amp is certainly not under powered to cause clipping damage and I never play my unit abnormally loud  - maybe 1/4 to 1/3 total volume.

As you can imagine, my repair/driver replacement will not be covered by warranty as this is not considered a manufacturer defect. I am told the tweeters run $399 per.

Worst thing I can do is have these repaired and then have it happen again. HELP!
gnoworyta
I've never owned ribbon tweeters, is there a chance they can be repaired by Millersound?
I'm sure they can but shipping from Dallas, Tx to PA would be a nightmare. My local dealer can repair them - I just want to know what possibly could have caused this (spike from amp?) and what I can/should do to prevent it from happening again...
I was only talking about shipping the tweeters to Millersound, not the whole speaker. Your lucky your dealer has the expertise to fix the tweeters.

By the way, I had four 7" scanspeak woofers, the two in each speaker, just stop working all at the same time.  Fortunately, the speakers were under warranty.  But before they would replace them the dealer wanted me to send in the nonworking speakers to figure out what had happened.  They could not.
Thanks. He will actually have to replace the tweeters.

My speakers are under warranty but my dealer stated as both tweeters were blown at once, it was caused by a "system problem" and not manufacturer's defect.

But my amp seems to be functioning normally, so????

Like I said, I'm at a loss to understand how this occurred and want to prevent it in the future, post repair...
Ribbon tweeters are delicate. That Parasound puts out 400 watts into the 4 ohm Proacs. If you have a DC leak with that amp it will damage those tweeters. BTW, my friend owns that speaker and it is one of the best speakers that I have heard!
A couple of thoughts here. What is the make and model of your primary source? One of the Brit magazines looked at CD players a decade ago and the surprising takeaway was that some of them had a significant amount of ultrasonic noise riding on the signal, independent of the brick wall filters.

Likewise, the latest fad in LP replay is to alter the RIAA curve with the Neumann time constant which can also create lots of ultrasonic energy.

If ultrasonic energy is passed to the amp it will be amplified and can damage the tweeters.

One other thought, many ribbon, or planar tweeters can just take a new, replaceable, diaphragm or can be rebuilt using the original housing and magnet structure. Best of luck, but do look for the source of the problem, having both go at once is concerning.
Um, you should check to see if the ribbons are truly what is damaged. Lots can go wrong in the crossover.

Best,
E
Thanks all. The primary source is a Parasound Halo CD-1 player. Also occasional vinyl via Rega P3. But all has gone well for 2 1/2 years using these...
If it really is the tweets, did you recently replace your speaker cables?? Sometimes high capacitance can lead to amp oscillation.
If it were me, I'd have the amplifier checked for DC leakage before having the speakers reconnected with the new tweeters. 
Thanks...

erik_squires - no new speaker cables. Have always used Kimber Kable - 9 gauge.
Weird. 

DC leakage on the amps won't cause this, because usually the tweets are protected by a capacitor. DC leakage would fry the woofers.

So, if you are _sure_ the issue is in the tweets, it's not DC, but it could be high frequency oscillation, which is hard to detect without a scope.
I'm with Erik. That's either a crossover problem or the amp is ringing. 
@gnoworyta,I use the same amp with my D48R and after your thread I am getting a bit worried. Did you try the amp with another set of speakers, if you have them? Did you switch off the complete system, wait for a few minutes (maybe an hour, etc), unplug the cables and connect back everything and try again? I am suggesting based on the good points that Erik is asking you.
Another possibility, in addition to those that have been mentioned (especially the possibility of an ultrasonic oscillation), is that a fault in the amp is causing a large but very brief transient at turnoff. (I assume, btw, that you are turning the components on and off in the proper sequence -- amp on last and off first).

I once had a high powered solid state amp, in that case a Threshold S-300, which developed a problem that caused it to put out what seemed like nearly a full power transient for a fraction of a second, about 20 or 30 seconds or so after it was turned off. In that case the transient was clearly audible, and produced visible movement of the woofers, but if such a transient is brief enough it might not be audible and might have sufficient high frequency content (corresponding to the rapid change in amplitude) to damage tweeters.

Also, what preamp and what phono stage are you using?

Regards,
-- Al
You may want to check for any DC offset at the amp speaker outputs.
Wondering, are the ribbon tweeters fuse protected? 
My MG 3.5’s have the ribbons fused. Additionally as others have mentioned, the ribbons are  fragile  and can be damaged by excessive air bursts from external sources. Could it be that someone has vacuumed cleaned the speakers? 
Again, thanks to all for your comments thus far.

I am using a Parasound Halo JC2 preamp and Musical Surroundings Phonomena phono amp.However, if I recall correctly, I was not using my turntable when I noticed the problem. Just spinning CD's.

I am unaware of any speaker fuse(s) in the Proacs.

My woofer/midrange drivers appear to be fine.

Unfortunately, I have no other speakers on hand to connect to my amp in question. I did power all down and then re-try, but my tweeters were still not functional. I can't be sure as they are covered by a wire mesh, but the foil ribbons may actually be a bit discolored in spots.

My takeaways thus far:

1. No one appears to believe the speakers themselves could be at fault.
2. "Testing" my amp would be prudent, although I have no idea how to do this (I'm by no means an electronics expert LOL). Who would be able to perform a check on the unit? The dealer I purchased the amp from is no longer in business.
 3.The speaker crossover problem mentioned - could this itself have caused the tweeters to fail or would that problem, if it does exist, have been ultimately related to the amp as well?

Forgot to mention - no vacuuming of the tweeters. I am very careful with my equipment - that's why this is so frustrating.
gnoworyta, no matter how this sounds I am just trying to be helpful. I realize you are trying to find the cause of your problem, not repair of the tweeter. I was just looking online and it seems the most common problem with ribbon tweeters is that the tweeter material, which appears made of an aluminum foil type material, rips. From what I read, if your problem is a ripped ribbon, it appears to be an easy fix for a professional, assuming it is not an exotic material.  Is it possible to visually inspect if it is ripped?  Also, if you can remove it from the speaker maybe you can isolate if it works ruling out a crossover issue.  I hope some of the guru's here can help out on how to test a ribbon speaker detached from the speaker cabinet.

Here is a YT of a RAAL being repaired. https://www.youtube.com/watch?v=bvylZF9eJOA

It may be your dealer knows that something else is burned out within your tweeter making it totally unrepairable. Like maybe a ripped ribbon tweeter still makes some noise, or whatever, and your doesn’t. But if your saying its $800 bucks for a new pair I would definitely investigate further. Millersound is first rate, give them a call. When my woofers needed repair he basically said he can repair most anything on the woofer regardless of problem.
jetter - appreciate any and all advice/comments.

My Proac dealer is supposed to be coming by this week to take a look at my speakers. I have no idea as to his level of expertise in regard to analysis/repair, so we shall see...

In the meantime, I welcome all input.
Regarding the possibility that the root cause of the problem may have been the speakers themselves, here are some excerpts from the following thread, although it is about a different Proac model:

https://forum.audiogon.com/discussions/proac-problem-tweeters-or-crossover

Audioconnection 3-10-2015

Having sold Proacs for 24 years
It could be a simple fix.
Unscrew and remove both top tweeter section knurled binding post nobs.
Insert carefully a small blade screwdriver into the hole and gently tighten the top binding posts clockwise a half turn till snug if its still loose go for another half turn but do not over tighten.
If this seems to get back your volume you are set.
If its still intermittent removing the woofer and get into the crossover board connection area and clean up the star washer x over board area where the binding posts meets the board will complete this.
Hope this works for you
JohnnyR


PBNAudio 3-16-2015

Jonny R from audio connection gives some good advise on terminals however don’t tighten them from the outside, open them up and tighten the nuts on the inside. Proac use Mitchell binding posts they have a knurled shaft you don’t want to loose the grip they have in the mdf plate that they are mounted in.


CTSooner 3-17-2015

PNB, that’s also great advice. I have had to do that with a few different Proacs that either I owned or my friends have owned. Wish that was fixed by them in the 90’s when they first encountered the problem.


Perhaps over time internal vibrations have caused a connection to loosen. And if that occurred at slightly different times in the two speakers, is it possible that it wasn’t noticed until the tweeters in both speakers stopped working?

Hope that helps. Regards,
-- Al

Tweeters in general are delicate and amplifier clipping can easily burn them up. Ribbon tweeters are in general the least robust type of tweeter. They are what I would call “rather fragile”. A large pop or click from switching inputs could have done them both in.
almarge - thank you

shadorneb- thanks. Scary to think they are that delicate. That said, I don't recall doing anything recently in operating my set up that I have not done over the course of the last 2.5 years, in which the speakers were fine.
Growing up we had a large with room with McIntosh gear and a pair of ADS 910 speakers.  When I played music too loud, with the loudness or the bass up too high on the C28 preamp, the 910 tweeter fuse would blow.  Looking back, my father was quite patient with me.  In true audiophile form, he always asked if I could notice that the highs were absent, rather than get angry about the fuse.  
Do you have kids in the house?
bjesien - nope, no kids. Wish I did - at least I'd have someone to blame!
gnoworyta,
Please be sure to post what the cause of the blown tweeters is after the dealer comes out.  I have a similar amp.
jetter - He really couldn't say. Although he did not "test" it, he said the amp appeared to be operating normally. He just said that somehow some sort of "system spike" had to have been generated to cause the ribbons to go. 
Well, that doesn’t help much as you originally posted to find out what was wrong so it doesn’t happen again. As I mentioned earlier, I had (still have) speakers with two scanspeak 7" woofers in each speaker. Same thing happened, turned it on one day and all 4 woofers dead. Sent them to the dealer for his inspection and he had the manufacturer replace them under warranty. Nothing like that happened again using same amps and speakers. I am sure you have it under control and sorry to sound like a broken record, but before spending the big bucks on completely replacing the tweeters if that is what your are thinking of doing, I would telephone Millersound and see if they can help. 
Jetter - thanks. You're right - not much help in ascertaining the cause. And although I understand their position that the speakers are not exhibiting a certain "defect in workmanship or materials", I think they still could have stepped up and assisted financially in some way.

Thanks for the advice on Millersound. I'll see what they say.

Either way, once I get these repaired, I will have to decide whether I feel comfortable continuing to use that amp, or bite the bullet and purchase something new. Have to keep cost down, so considering PS Audio Stellar...
I also was hoping that your dealer would come through for you.  Even if he was to just offer the tweets at dealer cost.  

I have read great things about the PS Audio Stellar amps.
... once I get these repaired, I will have to decide whether I feel comfortable continuing to use that amp, or bite the bullet and purchase something new.

Based on what has been said in the thread thus far, if in fact electronics in the system caused the tweeters to fail I'm not sure that the amp is any more likely to have been the culprit than the CD player.

Good luck as you proceed.  Regards,
-- Al 


https://www.parts-express.com/aurum-cantus-g2si-ribbon-tweeter--276-400

Guessing its probably this one with a different faceplate - which you could just swap from the damaged one.

Best of Luck

Peter


Thanks all. I welcome everyone's input..