Poorly Speakers - No HF

I decided today to get my old speakers out of the loft where they have lived for the past 15 years. This was prompted by the recent passing of their designer and maker John Chapman followed with a lovely chat I had yesterday with Phil at Nytech who wanted to know more about their history and have some photos for their website. The speakers became the Ion Systems JC-1 but mine were earlier prototypes, sold directy to dealers before they were made by Ion.

I couldn’t resist hooking them up to the main rig to see if they sounded as good as I remembered so I plonked them on to their stands (no spikes or blutack) and used some Linn K20 cable as the NACA5 I have is in trunking and the height is set for my Kudos S20’s.

I put on Sophie Zelmani – ‘God Do You Hear’ from ‘The World Ain’t Pretty’ and was immediately struck by how good they sounded, probably better than I remembered, no doubt heped by the kit that was driving it. They certainly reaffirmed my feeling that these are the best small speakers I’ve ever heard.

The track has a long introduction and just as he vocal kicked in everything went very dull and muffled sounding. It soon became clear that BOTH tweeters are no longer outputing sound.

I haven’t investigated further yet. The tweeters should be the same as used in the SBL’s which I know are being discontinued but I wonder if a crossover component could have failed, either cutting the output to the tweeter or worse sending a full range signal! I know John used Hiquphon tweeters as well, possibly the OW1-92 looking at the description.

The tweeter seems reluctant to come out. I suspect there’s some sealant in there. They are 35 years old or so. I need to have some time to try to remove them, possibly going in by removing the bass unit first and pushing them out (assuming the bass unit removes easily)?

I’m not sure what to do now. I don’t want to part with them but repair seems a bit silly too if they just end up being stored. I sometimes wonder about some ‘proper’ speakers in the conservatory but we’ve always resisted having anying on show.

Any speculation as to why they should both fail at the same time after being stored would be gratefully received!

For anyone interested here are some pictures.

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At that age, they are entitled to be stuck…!! But - equally - you have little to loose, in trying to get them out.

I guess another thought might be the crossovers have suffered - and thats where the problem lies.

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The tweeters do look like Scanspeak D2008s however, you should check whether they are the ones with Ferrofluid or without. Naim use the ones without.

I wonder whether one of them already had a failed tweeter - this can sometimes be not so apparent if the other one is working - and then the other one failed.

Still, provided you can still purchase replacements it shouldn’t be too difficult to repair them. Of course, that assumes that the crossover is OK.

The tweeters may well be sealed to the cabinet with Hylomar - this is usual with a sealed box speaker. So to remove you need to be really careful not to tear the veneer or even the cabinet wall.


I would tap a thread into at least two of the screwholes and screw in a bolt, that should give you enough leverage to pull them out. Especially if chipboard, don’t keep screwing in the bolts to push it out, but just pull on the bolts.



I recall John mentioning ferrofluid tweeters at some pojnt but what does make me slightly doubt this is that when the Scanspeak factory burnt down John supplied Naim with some tweeters. These would have been the non ferrofluid version from what you are saying. I need to get them out.

The cabinets were a originally sealed box, the port came later and was retrofitted, so there’s likely to be some sealant in play here.

The OP could also ask Oskar at Hiquphon as he designed the D2008 whilst at Scanspeak and Hiquphon still make a direct copy called the OW 1-92 - he’s always been very helpful to me via email. The Linn Kan designer told me there was no difference between the Linn unit and the original D2008 when Oskar first started Hiquphon, despite the mythology that says otherwise. Never directly compared them myself.


I’ve just asked some questions for you, the tweeter was most likely fitted with a foam gasket than has gone gooey.
Yes, try taking the bass unit out, that will also give access to the crossover and I am told the capacitor is the first thing to check.
Apparently there was a change in tweeter from prototype to later models, so not sure what is there. If you take the bass unit out then perhaps a phone camera or mirror will show any markings on the tweeter? Sods law says any label will be on the edge…

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Thanks for your help, it sounds like you have a source with some knowledge of this particular design?

A capacitor failure is quite likely, the speakers are at least 35 years old!

If it were a capacitor failure in the crossover would this have the effect of bypassing the crossover and damaging the tweeter or would it mute the tweeter?

OK, I’ve gone in!

I’ve only opened one up at the moment and have removed the crossover and drive units. The bass unit removed easily and I was able to push the tweeter out from behind.

The tweeter is open circuit so I can assume it is toast. It is indeed a D2008. How can I tell if it’s the ferrofluid version? The answer to this could be academic as stock seems low and it could be hobsons choice.

The concern is that if I replace the tweeters will they go again. i.e. how can I establish if the crossover is OK or not? There’s no leakage on the capacitors but concious of their age.

As an aside, it’s interesting that the tube on the back of the bass unit fits over the very small port on the rear of the cabinet.

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Are they more than 15 years old…? Yes. Replace them. They degrade with time.

Looks like there are 4 identical capacitors (marked as 5 MFD) in each Crossover…? So just get 8 of the closest modern equivalent you can find - and solder them in, noting the correct polarity.

35 years old! :grinning:

I think these capacitors are what is known as Bipolar meaning continuity isn’t an issue. I can’t see a marking for polarity on these.

My brother did his “year in industry” at Ion. He has two pairs of the active version, he was involved in the design of the active crossover for the Ion Nexus. He still uses that setup.
I will ask him to look at your pictures.


I would expect them to be Electrolytic, and so they will be polarised. See below -

PS. Looks like a near identical Capacitor can be obtained, with the same brand on it… :slightly_smiling_face:
Cost < £5-00 each…!!

Those look like early D2008s and they are without ferrofluid. The closest version of this that you should still be able to source is the D2008/851100, which is what you should look out for. Main difference is that the dome on the 8203 was doped IIRC (I seem to recall Linn used this on the isobarik). There’s also what appears to be a foam or felt ring on the front. You might want to try to salvage those so they can be reused. Failing that, I wonder whether there’s anything similar out there, or even some NOS items?

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Thanks Richard

The felt was added by John as he felt it improved dispersal. I think they would be easy to remove, the glue doesn’t seem to be as effective as it once was.

I would imagine, with music being AC, that polarity wouldn’t matter in this case?
Of course different in the case of DC.

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Maybe, but if I was doing it I would try to get the polarity as per the originals… :crazy_face:

YMMV, as always… :expressionless:

PS. Looks like the originals are well stuck in, using Silicone RTV (?). Hope you can prise them free.

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The Wiki article you helpfully posted does mention Bipolar electrolytic capacitors. Looking into this more I think all crossover capacitors are Bipolar?

I’ve always assumed they had polarity but apparently not.

I think I need to remove one and send a picture to a knowledgeable supplier, probably the same one I get the tweeters from, if I decide to do a repair now.

I’ve got him to look, the PCB is one of John’s, the tweeter not ferrofluid. Caps not electrolytic. He asks if one might have gone s/c with age and put a full load across the tweeter?
Cricklewood Audio have Alcap bipolars, compared to the cost of the tweeter it might be just as easy to replace them all.


I am a bit sceptical about that theory. It happened to both speakers at the same time?
Perhaps an issue with the amp when they were last used?