SpeakerTalk

Joddle · Posted: Thu Apr 07, 2022 4:07 pm Post subject:

I have had conflicting info regarding the crossovers in my Linn Saras and tried to raise this issues a while back but things got busy so I did not follow it up. My ones, (i.e. no dope or white cap and just two 8mm sockets and Linn branded Hiquphon tweeters) have not been sounding so good at the top end for a while and two things come to mind. Are the tweeters blown? or could it be a crossover issue?

What I notice is a definite lack of clear top end although when touching the the tweeter domes they do appear to be doing something as I can feel the vibrations. However with a listening test where I swap between listening to music between my TV and the Hi Fi, it is very noticeable that despite very poor overall quality, the TV does have much better treble response and by contrast the Saras sound rather muddy.

I wrote to Linn and was told by that the components in Saras are not affected by electrolytic caps changing so from that they suggested the issue to be with the drive units.

I also contacted Oskar at Hiquafon who said it could be the drive units but he does not do a repair service and suggested buying new OW3 units as replacements. but they are not cheap!

Then just a while back I was told the crossovers could in fact be the reason but I have no evidence to support that.

So without taking the boxes and completely removing both B200s, to get at the crossovers or removing the tweeters , is there a better way of testing the speakers to identify the true cause ?

And before anyone suggests it, no its not just my ears - on other speakers I can hear much better defined top end!!!

exkefman · Posted: Thu Apr 07, 2022 4:25 pm Post subject:

Hi

I'm surprised that Linn say that aging capacitors would NOT be a problem.

However: A quick google found this:

http://www.nodecorporation.co.uk/sara01.htm

And there's a rather nice crossover diagram showing a pair of capacitors (a 4u7 and a 5u0) in line with the positive input (going to the positive terminal of the tweeter).

So, any change in the value of these could be affecting the low frequency cutoff point of the tweeter (which could lead to damage of the voice coil, if the frequency is lowered and the voice coil is over driven by lower frequencies than it is designed to cope with), or it could simply be affecting the overall "voltage" (and hence the output level) of the tweeter, if the "inline" resistance has increased.

Given the age of the speakers, I would have thought that the capacitors might be the obvious thing to check/replace?

Instead of dismantling the speakers totally, you might be able to remove one of the tweeters carefully and then get it checked over independantly of the Sara crossover?

At least that might provide an answer as to whether it is the drive unit or the crossover (or maybe a combination of aging of both)?
_________________
regards
Tim

(I used to work for KEF from 1988-1995 - you can see my "profile" here: http://www.hifiloudspeakers.info/speakertalk/viewtopic.php?t=1706)

Joddle · Posted: Thu Apr 07, 2022 5:14 pm Post subject:

This is the email I received from Linn after asking about the Sara crossovers

Hi
Thank you for your e-mail
I can advise that we do not use electrolytic capacitors in our crossovers. It is more likely that the treble drivers have developed a fault than the crossovers having issues.
Best Regards
Colin
Customer Support
Linn Products Limited
Tel: +44 (0) 141 303 5194
Fax: +44 (0) 141 644 4262
Email: helpline@linn.co.uk

I think I may try and remove one of the tweeters and see if a cheap or replacement tweeter put in its place makes any difference! ( in fact there is proper one on Ebay for £50 which I may go for to use as as replacement test and then note the frequencies being heard. - If there was a dramatic change then it would confirm damage to the original drive unit.

As a complete aside, did anyone ever do a crossover upgrade kit for the Sara? A proper "one board" design instead of using two near identical units in parallel would be a nice option

exkefman · Posted: Thu Apr 07, 2022 8:49 pm Post subject:

Joddle · Posted: Fri Apr 08, 2022 6:31 am Post subject:

Of course another "question" that needs answering is whether the same issue is occurring on both speakers (to more or less the same degree)?

If it was just one tweeter, then you could swap the tweeters over (between the two cabinets) and if the fault stays with the same cabinet, it'll be the crossover, or if it "moves" with the tweeter to the other cabinet, then it is probably the drive unit.

To answer the first part - yes both speakers seem identically affected.

One factor may be that many years ago my very young kids managed to cause the system to go into violent feedback with the volume control turned up when they allowed the turntable arm to rest on the plinth. It was quite a few seconds before I rushed into the room and muted the system. As a result I had to replace two of the B200s but the tweeters did not seem to have suffered at the time - but who knows!!!!

exkefman · Posted: Mon Apr 11, 2022 3:28 pm Post subject: