Linn Isobarik tweeter replacement...with some pics

[nostromo]

I thought someone maybe interested in seeing how I replace the tweeters in my Linn Isobariks. I've done this procedure several times over years including on Kans Mk2. As I stated on the recent Isobarik thread, I blew the left hand channel front facing tweeter about 2 weeks ago after getting carried away with the volume (over position 90!) on some heavy rock music. The Willys returned from the business trip last Monday and I had a matched pair of Hiquaphon OW-1 tweeters delivered on the Tuesday...nice to see a fitting kit included (the first time I've seen this) comprising of some gasket tape, screws and even some solder...a nice touch.

It's easy to tell if the tweeter is blown, but just in case it was the amp, I swapped channels from the other tweeter and even did a resistance test (zero ohms) on the terminals for that tweeter ( I run active, there is no crossover in the speaker and each driver has it's own terminals, see pic below).

I lugged the bugger off the stand and onto it's back, removed foam grill and place a sheet over it much like an operating theatre, then a boxed kitchen cupboard door I had lying about in the shed. Remove the three Allen key screws, score around the tweeter with a scalpel (craft knife) to break the silicone sealant (Dow 785N clear) and screw about 1 cm from the edge of the tweeter as small screw. Use a cloth covered piece of wood for the claw hammer head and pull the screw up slowly. Removed the hot glue with a knife and pliers and de-solder. Clean up the hole and remove as much old silicone as easily possible. I tried to clean the wire ends of the solder but that proved too difficult so I opted to cut off about 1 cm from each wire. Soldered the new tweeters to the wires (I forgot to use the hot glue, but I think that's a bit OTT, but Linn did use it). Placed a thin bead of silicone on the lip of the hole all the way around and placed the tweeter back, screwed down carefully, remove any excess silicone. Clear up and place the speaker back on its stand and connect all the wires and have a good Hoover around the room....Job done! I allow overnight for the silicone to cure before playing it...I did check the resistance on the tweeter terminals (5.6 Ohms) once finished.

Comments/suggestions appreciated.

 

[Richard Lines]

@nostromo - Have you not considered replacing all four tweeters with some 'better' ones. OK in some cases this may require some woodworking but there is a lot of information that these tweeters simply don't reproduce. I didn't fully appreciate this until I replaced mine.

The Sara9's I have also have replacement tweeters.

Regards

Richard

 

[nuit73]

What sort of better tweeter you put on isobarik?

 

[Bob B.]

To save drilling a hole in the tweeter, (eg. If you need to re use, or sell a working one), you can also screw an easy out into the fixing hole, and pull with a pair of molegrips. Done loads like this.

 

[charly63]

Hello all,

If you have change yours 4 originals tweeter(Scanspeak or Hiquphon D20-LP-1) by 4 new Hiquphon OW I.
You must change/modify the value resistor by increasing it from 2 to 2.5 OHMS.
Same for Sara( included the 9's).

Regards

 

[nuit73]

And what other tweeter for upgrade on Isobarik?

 

[nostromo]

@nostromo - Have you not considered replacing all four tweeters with some 'better' ones. OK in some cases this may require some woodworking but there is a lot of information that these tweeters simply don't reproduce. I didn't fully appreciate this until I replaced mine.

The Sara9's I have also have replacement tweeters.

Regards

Richard

Yes I have on many occasions but decided against it. My first experience was with Kans Mk2, while playing Vangelis very loud a sudden 'Glockenspiel' or chime bar took out both tweeters. So I spoke at length with Oskar of Hiquaphon and he suggested that for a little extra cost I could go for his superior OW-2 tweeters. So thinking I could have even better Kan's than Linn designed I bought a pair. Once fitted I was very disappointed, the treble level was much higher and the speakers became too bright for my liking. I had to order the right pair (OW-1) after a month of trying to live with my mistake, anyway the OW-1's restored my MoJo.


A good friend of mine has Isobariks, he had the cabinets routed out so they could take Scanspeak tweeters. He has tried the Illuminator tweeter and one of the Revelator range from Scanspeak and I've heard these and found them on the whole to be unsatisfactory (mostly too bright and fizzy), they were also prone to blowing very easily when the wick was turned up. He now uses Morel tweeters, I'm not sure of the exact model, but he's able to repair these if they blow with an interchangeable part. These Morels seem to have a much better power handling capability than the scanspeak and blow much less often. He is currently running the Morels and these to my ears sound very good (rich, detailed and smooth). As an aside he has also replaced the mids for the 5 inch Morel version (I'm not sure of the exact model) and the B139's are now the new Falcon Acousitics model, which I really like and have been trying to talk myself into getting, but I'm wary of damaging the cabinets and the cost (maybe next year ), they are faster and tighter, less flabby.


Personally, I like what the basic Hiquaphons do, they are in my opinion closest to the original Linn tweeter (which as you know was also made by Hiquaphon). I've heard several vintage Isobarik speakers with ageing tweeters and believe a very effective upgrade can be achieved by a simple swap to the OW-1 tweeter, in fact I would recommend anybody using Isobariks with the original tweeters to renew all four tweeters to the OW-1s and they might be surprised with the uplift in SQ. It's not that cheap to do, best part of £750 for 2 matched pairs currently...perhaps try the front pair first as an experiment.


I have not changed drivers in the Sara speaker.

Were you experimenting with the IMF bass units? if so how's it going?

 

[nostromo]

What sort of better tweeter you put on isobarik?

I really like the Hiquaphon OW-1 tweeter and recommend this highly. These are a close match to the original Linn tweeter and a direct replacement (very easy to fit).

 

[nostromo]

Hello all,

If you have change yours 4 originals tweeter(Scanspeak or Hiquphon D20-LP-1) by 4 new Hiquphon OW I.
You must change/modify the value resistor by increasing it from 2 to 2.5 OHMS.
Same for Sara( included the 9's).

Regards

I run my Isobariks in active mode and believe that the impedance is less of a concern as there is no passive crossover in the circuit. The resistance (not impedance) measured by a simple multimeter reads 5.6 Ohms at the terminals. The tweeters I'm using are the OW-1's here.

 

[nostromo]

And what other tweeter for upgrade on Isobarik?

The hole-size in the cabinet and the screw locations restricts too much experimentation without modifying the cabinets. Your choices are the scanspeak equivalents from Falcon Acoustics but I prefer the Hiquaphon OW-1s. If you do modify the cabinets to take other tweeters you should take care as the cabinet is very old and low quality (compared to these days) chipboard. Also it's a good idea to match the sensistivity and imepedance as close as you can to the originals.

 

[cctaylor]

I fitted Hiquphon OW2s to my active Isobariks as recommended by Oscar for active setups. I purchased a MiniDSP Umik 1 and so that I could check if I needed to adjust the NAXO due a slight difference in sensitivity compared to the original Scanspeak tweeters. In the end I didn't actually adjust the crossover.

 

[nostromo]

@nostromo - Have you not considered replacing all four tweeters with some 'better' ones. OK in some cases this may require some woodworking but there is a lot of information that these tweeters simply don't reproduce. I didn't fully appreciate this until I replaced mine.

The Sara9's I have also have replacement tweeters.

Regards

Richard

I forgot to ask....which tweeter are you using?

 

[tpetsch]

IIRC a 10-32 machine screw will self tap into the tweeters mounting hole, simply screw/tap it in and when the screw bottoms out keep turning and the screw will then help to pries & lift the tweeter out of it's potentially sticky situation depending on how much and what type of adhesive they were using that day/run.

 

[nostromo]

@tpetsch I've not tried that method... Its a method worth keeping in mind, it would be particularly useful if the tweeter being removed was a good one. I'm very wary of damage to these vintage chipboard baffles, if a bit cracked off I'd be in a world of woe... Thanks for the suggestion.

 

[Richard Lines]

I forgot to ask....which tweeter are you using?

I'll need to inspect them as it was actually done by the previous owner.

Regards

Richard

 

[James]

I'm very wary of damage to these vintage chipboard baffles, if a bit cracked off I'd be in a world of woe...

It's chipboard. A bit of bondo or epoxy filler and a coat of paint will make it whole again.

 

[stuwils]

I used to use the Ninka neodymium tweeters in my active bricks and felt them to be a worthwhile upgrade, I suppose the are unobtainable now though.

Rgds
Stuart

 

[Richard Lines]

Were you experimenting with the IMF bass units? if so how's it going?

I have yet to start the alternate bass unit experiment with my standard pair of Isobariks. I obviously have the units I'm just lacking the time/ inclination - ideally I also need to buy a set of the new Falcon B139 units...........

I forgot to ask....which tweeter are you using?

It looks like they are Hiquphon OW1 units without actually removing them.

Apologies for the belated replies.

Regards

Richard

 

[-alan-]

I still have my very early Isobariks sitting passively (ahem), waiting for me to get off my rear and install multiple new tweeters. Cost has always been a bit of a disincentive anytime I looked at it in the past.

Are there any reasonably affordable ones around on the market days ?

 

[Craig B]

I did check the resistance on the tweeter terminals (5.6 Ohms) once finished.

Comments/suggestions appreciated.

Nice write-up and pictures. Other than agreeing with the other comments regarding inserting a machine screw into an existing driver mounting hole, I'd only suggest that it is always best to check resistance first, before installing a drive unit, rather than once finished, especially so, when there is adhesive and/or claw hammers involved.