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Tweaky

Harbeth Radial driver fault, can it be fixed?

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When I turned on my system yesterday I was horrified to find a very distorted sound coming from one of my Harbeth SHL5's.

Listening up close it was obvious that the main Woofer/Radial driver had something seriously wrong with it.

I first did the usual diagnostic tests to see if it wasn't the amp [swapped terminals around] and have since taken the driver out of the cabinet.

 

When still in the cabinet, there was still sound coming from the driver, but hugely distorted, once out of the cabinet I tested it with a multimeter and that was fine as I got a number proving it wasn't dead, then got a 9v battery and the cone moved, as it should if OK, but when it did the whole spider assembly moved with it, which exposed the voice coils [which seemed fine, no sign of burn out]

 

5abd855b5ec9d_HarbethDriver007.thumb.JPG.dfc1170afd3f946ec2b09bde3eeb7f77.JPG

 

Would it be just this glue failure after many years that has caused the spider to part ways with the speaker basket be the sole cause of this distortion, and if it is, one would suppose that gluing it back again will fix the problem.

 

 

What would be a suitable glue to use.

The spider material seems to be some sort of corrugated woven material, and the speakers basket is a form of high density plastic.

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Selley's contact adhesive would be my first choice in readily available glues. It  does appears that the paint is peeling away from the speaker frame and it is not the original adhesive that is at fault.

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There is no paint on the speaker basket, it's a molded heavy duty plastic.

I think it might be because the plastic is not porous that the glue has failed, and it's not just in one place, it's basically 320 degrees of the circumference that the glue has failed.

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Is the adhesive black in colour or is the outer circumference of the spider attached to a cardboard ring? If the original glue is black, then it could be Moyen RS-3087 cement or a  similar type.

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Posted (edited)

The spider appears Blue at the top, and Black where it glues to the basket.

IMG_0010.thumb.JPG.324c639767bd1d22a0bfbaa442b02357.JPG

IMG_0011.thumb.JPG.8641564054e188711442ae36c6a3cd98.JPG

 

Thankfully the spider is still partially attached to the frame, so with any luck centering it again [ which is it's sole purpose of centering the cone] shouldn't be a problem.

Edited by Tweaky

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Posted (edited)

Use  the Selley's contact adhesive sparingly,  apply to the frame only and then push the spider down while the glue is wet. Test that the voice coil is central while the glue dries.          

 I should add that you will need to wait at least 24 hours for  the adhesive to thoroughly  set before using the speaker.

Edited by VanArn
additions

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 Selley's , Kwik Grip, solvent based contact adhesive ( Horizontal ).  Available in 100  or  50 mL tubes.

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OK, thankfully Selleys horizontal contact adhesive is available at the supermarket, so it has been bought and applied.

 

Now the 24 hour wait to see if this has solved the problem.:unsure:

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Posted (edited)

I just reinstalled the driver and am happy to report that the repair went well.

Whew ! that's a relief

 

EDIT: See post below.

Edited by Tweaky

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Well I thought it might of been a bit too good to be true. :(

 

After I had reinstalled the drive, it sounded OK at first, but then after several hours at low volume [ conversation level] a bit of distortion started creeping back in again, then I turned the volume up a bit to see if it really was the same driver that had the problem, the distortion became a lot worse.

 

I removed the driver again and had a look at it, it looked ok, but when I pushed on the cone  I could feel and hear friction......it seems I didn't quite get in centered when I glued the spider back onto the basket :blush:

I had read elsewhere that to glue either a spider or new surround onto a basket, you really need to remove the dust cap first and use pieces of paper as spacers on the inside of the cone, to create the correct gap around the voice coil......I didn't do that, as the Radial drivers dust cap doesn't really look like it's used glue to attach it, it seems more like a sort of heat treatment as been used [ ? ]

 

Anyway, I thought, well why don't I just try and remove the new glue and try doing it again, so I went to Bunnings and got some Glue Rid, which is what is recommended by Selleys to soften Kwik Grip cement so you can un-glue things again......seemed like a good plan until I read the ingredients on the tin and  realized that this Glue Off was actually a powerful solvent, and since the Harbeths Radial driver is a form of plastic, and so is tha basket, I could have possibly have damaged the driver and basket if I had applied it....so I canned that idea.....a averted disaster is the way I'm looking at that close call.

 

Ok, so there wasn't much for it except to try and separate the freshly glued spider again from the basket with a scalpel, worked for about 5cm, then the scalpel caught a tiny bit of glue and cut a small tear in the spider....Arragh! :oops:

 

So now the state of the driver is.....working, except for a partially torn spider that is glued out of alignment.

 

Prior to any of this happening, and prior to my original post, I had sent a email to Harbeths Australian distributor Audiomagic telling them of the problem and asking if were they, or Harbeth UK I should be talking to, as the speakers are well out of warranty......I'm still waiting for a reply.

 

Since then, and especially now because of the new situation where the spider itself is probably going to be needed to be replaced, I have contacted Harbeth UK about the problem asking if I can send it to them for repair.

You might be thinking, well to ship it to the UK, have it repaired, then shipped back again, you might as well get a new driver......I don't know what the cost will be, apart for a 2KG parcel air freighted to the UK is Aus$60.

It's probably a 30 minute repair in the right hands, with a 24 hour glue dry, and a spider shouldn't cost very much to replace [he say's hopefully]

 

The thing that makes it my BEST option, is that the drivers in Harbeth speakers are all matched pairs, they all go through soak and phase tests among other tests, and have the measured results written on stickers attached to each driver, plus Harbeth have all that same information about every detail of my speakers at the factory, so if they repair it they will make sure it comes back to me dead on spec so it matches my other speaker.

 

People wonder why Harbeth speakers cost what they do since there doesn't 'seem' to be that much high tech involved with them.....I think that last paragraph about the driver matching, and support sort of explains it.

 

Oh well, I'll update this post, which is slowly becoming a bit of a saga, when I get a reply from Harbeth, which from previous dealings with them should be quick.

 

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Hey thought I'd chime in being a Harbeth dealer. I'd agree that if you replace it, go for a matched pair. If they're not going to airfreight separately, then know that the next local shipment is scheduled to arrive in Oz late June. If you can have them delivered with the distributor's shipment that should save you on shipping $$. 

 

I have no idea on costs, but hopefully it's justified for you to be able to do it. Good luck! 

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OK, thanks for that info.

 

I think I'll wait for Harbeth's response and see what they recommend, several reasons for that, but the main one is that I'm sure a driver repair will be a LOT cheaper than any other option, plus it would probably be the quickest fix as well [ Air freight to UK is 8 days ].

 

From reading the Harbeth users group posts, I know they used to happily send out a replacement driver to Australia, but that was when we had no distributor.

 

A replacement single 'Old Spec' SHL5 Radial driver that matched the one in my other speaker would be the next best scenario [they would have those specs on their books once given the serial numbers ]

 

It's become a bit problematic because of the slight change of the cone material in the Radial driver as used in my speaker, to Radial 2 material, as used in the SHL5+.

 

 

 

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OK.

So I got a reply from Harbeth UK.....[Still deafening silence from Audiomagic, Harbeth's Australian distributor, even though I emailed them several days prior to my email to Harbeth UK :( ]

 

Here's their reply, and might be worth noting for other Harbeth owners that might have a failed driver in the future.

 

Unfortunately the drivers are not repairable due to the strong super-gules holding a lot of the parts together. A re-cone after the old cone/surround/suspension assembly has been removed and all the old glue residue picked off rarely works so its just not cost effective.

As we keep very detailed log books we are able to supply a matching replacement but the cost of shipping from us to Australia won't be cheap, that's my only concern.

The replacement drivers are £198 each.

If you would like to go ahead, no need to send the faulty driver back of course , please confirm and send me your full address and the speakers serial number (on the back of the speaker cabinet, not the faulty driver) and I will work out a delivered price for you.

 

So now it only a matter of 'Bill Shock' before my speaker is up and running again....the Aussie dollar is currently at $1.83 to £1....I'm resigned to the fact that this isn't going to be cheap.:ohmy:

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Good morning..

 

I would be dark on the Au distributor to say the least. As you say these are expensive speakers and Im sure Harbeth directly would be none too pleased to hear you have not have an adequate response from their agent.  I must admit if it was me Id be on the phone directly to Harbeth in the UK. Get an answer from the factory themselves. Waiting on dealers replies would frustrate me especially if they operate at glacier speed.  Alan Shaw is active on the user group and there is alot of very helpful stuff there.  All the best going forward.

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Definitely call Harbeth direct. I had a poor experience with the Aussie importer of another English brand (do a lot of studio gear but will remain nameless although there’s an A, a T and a C in the name). Next time I needed assistance I rang the UK factory direct and they couldn’t be more helpful.

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I would suggest that you send the speaker to a suitable repairer.  If you are concerned about the  close matching of the  drivers, then you will have to send both the faulty one  the other SLH5  unit together so that the T & S parameters can be obtained for reference purposes.  The  cost and freight for a replacement  direct from Harbeth  is on the expensive side .

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As mentioned in the reply email I got from Harbeth, there is no need to send the speakers in, they have records of the exact parameters of the broken driver as it was originally measured and can send a matching one to just drop in as a replacement.

Actually some of those measured parameters are written on a sticker on the side of the driver.

 

There is a YouTube Harbeth tour somewhere that shows what they test, and it's against the one reference Radial driver that's kept in a sealed box when not in use.

 

Many many years ago [mid to late 70's] I had a job testing speaker drivers, put it this way, if they could reproduce the test tones they were considered fine, but I can tell you that there was a huge variation between drivers which you could tell by ear.

Looking back at those speaker drivers, how anybody built a set of speakers that had drivers that had a 60% chance of being quite dissimilar is beyond me, just a small difference in the Gauss charge of the magnets would cause a difference in loudness between two drivers, let alone all the other small manufacturing variables that can occur.

 

I think Harbeth have their in house manufacturing well sorted by the look of the broken Radial driver I have sitting next to me, it really is well built, and if not for some failed glue around the spider assembly  would probably still be working for another 20 years at least.

It's just a pity they think it's not worthwhile taking it apart and reassembling back again with a new spider.....Oh well, I guess I can always have a shot at it myself once the replacement arrives

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Thanks for the updates on this Tweaky. Athough expensive, your paying a fraction of what a new set of speakers would cost.

 

After seeing how good Harbeth's post warranty support is, I'll most likely be investing in a set of Harbeths when I buy my new speakers.


 

 

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Posted (edited)

Unfortunately for me, this driver replacement has become a bit of a saga.

 

I don't know what the going on's is between Harbeth and their Australian Distributor; Audio Magic [or should that be Tragic]

But on my most recent email reply from Harbeth [Today]...I eventually was recommended the same cause of action as recommended a few posts ago, that being getting the replacement driver shipped to Aus with the next shipment of Harbeth speakers to Audio Magic.

 

This has dragged one for far too long, and could have been sorted long ago, but hasn't.

 

As I reiterated  in my last email to Harbeth, I'm a bit pissed off ATM, and don't want to deal with Audio Magic at all, or needlessly wait any longer that I have to with for a replacement driver.

 

Hopefully things will get sorted ASAP.

I've given a link to Harbeth to this thread.

 

EDIT: It has been sorted, as I've been promised, by Harbeth directly via emails sent [thankfully Andy Sinden at Harbeth has a sense of humor ], and as soon as he has finished bonking his girlfriend over the weekend......Go Lad...will sending me a replacement driver on Monday.

Edited by Tweaky

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Here's a interesting *** Bit about Harbeth Radial drivers that I didn't know previously, and other Harbeth owners might be interested in.

It would seem that Harbeth have been constantly refining the Radial driver design of the SHL5, but without giving any outward indication that this has been going on.

 

This became apparent with recent correspondence with Harbeth directly in the process of replacing my failed Radial driver.

 

It seem Harbeth keep various 'Spec'd' drivers of this evolution on hand as reference, then as needed, if a driver of a older spec'd driver is needed as a replacement [and not currently at hand], several drivers will be asked of the production line to be made using the respective material used in that version, then of those drivers made, and the one closest to the parameters of the measured driver, in the original speaker, is sent as the replacement.....all known by the serial number on the back of each speaker.

 

Apparently the Radial driver in my SHL5's is a V4, so since apparently no V4 drivers that fit my spec are currently in stock , a batch of V4 Radial drivers has been ordered to be made up at Harbeth ATM.

 

Name me one other manufacturer of ANYTHING, let alone HIFI Speakers, that go that far to "Get it Right"?

 

Amazing speakers, and a truly amazing company......had a few hickup's getting this far to date, but I think that's because Andy Sinden at Harbeth is over worked.

 

He is a true gentleman, and a pleasure to deal with.................. I think once I take delivery of the replacement driver, a VERY nice bottle of Australian RED might be heading to Harbeth with his name on it, depends on what I'm hearing about a Tax on gifts sent to people in the UK is correct, apparently you have to declare the worth of goods sent to the UK now, and a TAX is imposed on the recipient as a percentage of the gifts value, if they want to collect it.....WT F

 

 

Edited by Tweaky

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