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It is currently Sat Nov 22, 2014 9:14 am

Another Ribbon Fix Attempt - please talk me down...

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rooze

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Post Sat Jul 13, 2013 11:53 am

Another Ribbon Fix Attempt - please talk me down...

Hello folks,

Please indulge me for a minute whilst I try and explain my thoughts and ideas -

I have a set of Carver originals with the Plat 60" ribbon upgrade.

I bought them in January, one side buzzed, and now, in the warmer weather of Summer, both sides buzz like a kazoo.

I've investigated as many options as I can think of to overcome these problems, including of course the hair dryer technique and tensioning bolts around the area of buzz.

I've had ads running on Craigslist, Agon, Circle and Asylum, and of course this site too, but it hasn't resulted in a replacement/fix.

I purchased a used unit on eBay for over $500 and it arrived in pieces - dislodged magnets and a torn ribbon. That experience has put me off anything which involves shipping, including the option of having the ribbons professionally rebuilt by the operator of this website. I've tried to justify driving these to Florida myself and waiting for the rebuild, then driving them back. Or, shipping them down, and driving down a week later to pick them up. But it's a haul from Green Bay WI and I can't fit it into my schedule (nor justify the costs)

So I'm looking at the ribbons with a hammer in one hand and a screwdriver in the other, intent on mischief. (there's little to lose at this point).

So, what I'm thinking of, and what I'd appreciate some guidance with, is coming up with a way to add tension to the ribbon, in the way in which you might tension a guitar string. Obviously not via a rotational tension but via some lateral tension.

I haven't opened them up, nor have I removed them at this point from the speaker, so I'm basically reconnoitering a potential fix and looking for advice.

I see that protruding from the ends of the ribbon enclosure are what looks like a PCB, with 3 nuts/bolts fastening it to the ribbon assembly. I'm assuming that the ribbon foil is attached in some way to that PCB.
What I'm considering is this -

Remove the units from the frames and set them on the bench.
Loosen off all the screws which hold the magnets in place, not so they're completely loose, but essentially un-tensioned.
Loosen off the 3 bolts on the ends of each PCB.
Try to prize the PCB away from the ribbon enclosure, gently, ensuring it isn't broken. There looks to be some kind of adhesive in use, so I guess I'm just trying to break the bond of that adhesive so the PCB's are somewhat free to move. Since the magnet bolts won't be completely loosened, there won't be much 'lift' between the PCB and the ribbon assembly frame in which to free the bond. So maybe I can insert something like a spark-plug feeler gauge between the PCB and the frame, to try and break the adhesive bond???
Then, clamp the ribbon assembly firmly to the bench.
Then, attach small clamps to the protruding part of the circuit boards, being careful not to crack the boards by loading them vertically. I'd need to make some kind of jig or support for the clamps.
Then, basically tension the clamps outwards from the ends of the ribbon assembly so they're pulling on the ribbon, like a guitar string. Of course, I wouldn't apply much tension, just enough to perhaps result in a 0.5mm of movement, or less.
Then, with the clamps still under tension, re-tighten the bolts holding the PCB and retighten all the magnet bolts.
My theory is that that would then clamp the retensioned ribbon firmly in situ.

So I guess what I need is for someone whose actually opened one of these things up to point out the folly in my assessment.

is it feasible, if conducted under a very careful and controlled environment, or is there something physically preventing this method from working?
My main concern is that the PCB is bonded to the assembly and that it won't move sufficiently to tension the ribbon.
Though I'm assuming that when these units are assembled from new, there was some tension applied via a similar process, albeit without the magnets in place, perhaps.

Any thoughts, suggestions would be appreciated. Again, at this juncture there isn't a whole lot to lose other than my time. And I'd prefer not to waste that if people think this is destined to fail.
If that's the case, can anyone make any other suggestions which haven't been explored around here?

One last point -

The left side ribbon worked flawlessly when I bought this during the Winter. Now, in the warmer, humid weather, it actually buzzes worse than the other side.
My concern and question is - do newly rebuilt ribbons work without ANY buzz, or is there a tendency for some to buzz even after a rebuild. In other words, is this buzz issue inherent in the design?

Thanks for any feedback/comments/ideas etc

Rooze
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F1nut

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Post Sat Jul 13, 2013 12:13 pm

Re: Another Ribbon Fix Attempt - please talk me down...

Send them to Dave S. for repair and follow his shipping instructions. He will ship them back packed so they will not get damaged.

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TNRabbit

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Post Sat Jul 13, 2013 9:46 pm

Re: Another Ribbon Fix Attempt - please talk me down...

F1 Nut speaks the truth.

Do you live in a humid environment? Some have used a de-humidifier with good results to counter similar problems.

No, buzzing isn't inherent in the design. I've had a pair of AL-IIIs for going on 7 years now without an issue.
TNRabbit
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rooze

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Post Sun Jul 14, 2013 11:49 am

Re: Another Ribbon Fix Attempt - please talk me down...

It's quite humid, but nothing like being down in say Florida or LA....I'm in NE Wisconsin.

And it doesn't actually equate fully to humidity, it's really just the warmer temps. At the start of Summer the humidity was low, but the 75+ temp was enough to get the left side buzzing. It's odd really, the right side has visible signs of damage, thus the buzzing is expected, yet the left side looks flawless and performed so throughout the Winter. It's that which prompted my question about inherent problems in the design.
I guess it's just old age. I mean, I'm probably doing whatever the human equivalent of buzzing is....farting, wheezing, popping or whatever :rolleyes:

Anyway, I'd be loath to have my living conditions dictated by a pair of speakers, regardless of how good they sound. If they were in a dedicated listening room that would be one thing, but the room serves as my workspace office and TV/projector room. So running AC or even a dehumidifier all day long isn't where I want to be at.

The hammer and screwdriver idea looms ever closer :(
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angelod307

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Post Sun Jul 14, 2013 12:07 pm

Re: Another Ribbon Fix Attempt - please talk me down...

I have a rebuilt set boxed up ready to go 775.00 shipped.
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angelod307

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Post Sun Jul 14, 2013 10:33 pm

Re: Another Ribbon Fix Attempt - please talk me down...

Oh yeah, i forgot, step away from the ribbon. It will bite if opened and angered.
CarverFest: I just go for the arts and crafts
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Robert R

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Post Wed Jul 17, 2013 7:57 pm

Re: Another Ribbon Fix Attempt - please talk me down...

To fix those ribbons you would need some aptitude and determination, atributes you probably have. But you also need three more things: proper instruction, a lot of practice to develop the necessary "touch", and proper materials. You are not likely to acquire any of those three. And even if you did you wouldn't want to start with 60" ones - they are a lot more difficult to assemble than the 48", which are tedious enough.

You have to use the original type of ribbon material. If you got all 60 magnets re-glued and polarized right, and if you could manage to find some substitute ribbon material that actually worked, and if you got it in, centered, and tensioned so it neither buzzed nor tore, it would still not sound like a Carver ribbon - you need the OEM Kapton, period. And they don't sell small quantities - 1000 foot rolls only, I believe, made up on special order.

The screws do not hold the magnets at all - they hold the sections of bracket together, sandwiching the ribbon and overcoming the quite considerable magnetic repulsion. The ribbon design is not something to worry about generally (Dave says the humidity doesn't cause permanent damage, just funny sound until they dry out), but after 20 plus years the glue that was used back then to hold the magnets in place has become brittle, and the shock of shipping was all it took to dislodge a few. An unglued magnet spells instant, inevitable, irreparable ribbon destruction.

Send them to Sauters, and be darn glad they are there - without them most of these great speakers might have been shitcanned by now. They are personally,exclusively authorized by Bob Carver, and there is no other shop that is. They do a re-glue job on the magnets and get them all back in with the correct polarity, then install new Kapton and pull the whole thing together with the right amount of tautness, nice and straight (while the two halves fight like pure hell to slip sideways). The ribbons come out just like new - probably a bit better, because of a few tricks learned over a couple of decades.

Or, if in a hurry, buy angelo's pair - these doubtless have been rebuilt by now, by the same people.

Robert R
"You know what folks? I'm happy."
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rooze

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Post Thu Jul 18, 2013 3:02 pm

Re: Another Ribbon Fix Attempt - please talk me down...

Thanks for the thoughtful response, Robert.

In my assessment, I hadn't thought to separate the two sides of the magnet support, just to loosen the screws enough to free the PCB's, then try to fernangle some movement/tension, outwards, in the horizontal plane (horizontal if laying on a bench[the speakers, not me [-X ]).

The unknown element to me is whether or not those PCB's can be made free to move, without a major dis-assembly.

All told I'm sure you are right, to trust in the experts. Also, you've just said something which I hadn't realized, that is the magnets are re-glued as part of the refit. When I bought one of these from eBay, it arrived with the magnets dislodged, so that became my main concern over shipping. But if they're re-glued, that should be less of an issue. So thanks again for the advice.
Angelo - you and I have tried to hook-up in the past, via a thread and via a number of PM's. I'd agreed to buy those from you on 2 occasions, but when we got to the final step, you must have gotten busy or something, as the communication dried up.

Cheers all

Rooze
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frenchguy

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Post Thu Jul 18, 2013 3:29 pm

Re: Another Ribbon Fix Attempt - please talk me down...

Or, you Could Just give me the speakers since Im about 40 miles from you & angelo Could give me the ribbons when :lol: I see him at Carverfest & everyone would be Happy !! Well Maybe not you or angelo but I would !!! \:D/
Carver M-4.0t & Rollandized tfm42, ct-6 & ct-17, sda390t, jolida jd 100A & JBL L96,s Modified JBL 4401,s W/Ribbon Tweeters, Carverfest vacuum tube amp & CF Linestage, Dared SL-2000A tube preamp, Carver AL3 Amazing speakers in natural oak, Carver Cinema 5.1 subwoofer & Douglas connection cables
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Robert R

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Post Thu Jul 18, 2013 4:34 pm

Re: Another Ribbon Fix Attempt - please talk me down...

The little PCBs are not a problem. Three little bolts and locknuts on each and they fall right out. They have foils arranged to line up with the aluminum traces, to make solderless electrical contact [soldering to thin aluminum being a near impossibility]. They don't hold anything together, and in fact are the last thing the rebuilder reinstalls.

Moving the Kapton ribbon is a big problem, because it tears easily and is thoroughly stuck in place. It always comes out in little pieces - the rebuilder has to scrape it out.

Robert R
"You know what folks? I'm happy."
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angelod307

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Post Fri Aug 02, 2013 12:01 pm

Re: Another Ribbon Fix Attempt - please talk me down...

rooze wrote:Thanks for the thoughtful response, Robert.

In my assessment, I hadn't thought to separate the two sides of the magnet support, just to loosen the screws enough to free the PCB's, then try to fernangle some movement/tension, outwards, in the horizontal plane (horizontal if laying on a bench[the speakers, not me [-X ]).

The unknown element to me is whether or not those PCB's can be made free to move, without a major dis-assembly.

All told I'm sure you are right, to trust in the experts. Also, you've just said something which I hadn't realized, that is the magnets are re-glued as part of the refit. When I bought one of these from eBay, it arrived with the magnets dislodged, so that became my main concern over shipping. But if they're re-glued, that should be less of an issue. So thanks again for the advice.
Angelo - you and I have tried to hook-up in the past, via a thread and via a number of PM's. I'd agreed to buy those from you on 2 occasions, but when we got to the final step, you must have gotten busy or something, as the communication dried up.

Cheers all

Rooze



Yeah, i am at a loss. I have nothung but time. Still available. My email for quicker responce is angelod307@msn.com you are correct, that my memory is not as it should be from day to day. I forget to check in here. So i am truly sorry. On a good news front, a person i talked to a year ago and had a similar issue just bought amp i have. So all hope is not lost.
CarverFest: I just go for the arts and crafts
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angelod307

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Post Fri Aug 02, 2013 12:06 pm

Re: Another Ribbon Fix Attempt - please talk me down...

frenchguy wrote:Or, you Could Just give me the speakers since Im about 40 miles from you & angelo Could give me the ribbons when :lol: I see him at Carverfest & everyone would be Happy !! Well Maybe not you or angelo but I would !!! \:D/

There is option. I could take them to carver fest for tranport back. If that is the case , it would be less the shipping. Yahoo.
CarverFest: I just go for the arts and crafts

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