SL2 tweeter - need for matched pair?

The SL2 tweeters were first selected and then matched.  It may be that on the basis of the serial numbers Naim can supply you a close match to your remaining tweeter, however, as an SL2 owner, if it were me, I might well be wanting a new pair.  Either way, Naim should know what's best here.

Availability notwithstanding, bare speaker units, especially tweeters, are generally not expensive and there's not a great service cost for installation. If one tweeter went on me, I'd be wondering how long until the other goes? I'd buy a matched pair if available and have both done at once. Peace of mind worth the cost in my view.

True Joe, but there's a considerable extra cost for the selection (much depends on yield) and matching.  However, as I say, Naim should know what's best here.

I don't have these speakers, but if I did and it were me I would buy and change both tweeters and keep the working one as a spare....

best

David

I changed one on my NBLs after one blew and, as an experiment, tried them with one old one new.

Having done so, I was very happy I had purchased two and could change the other one over as well! Even when working, they "go off" over time more than I would have thought to be the case.

Anyway, the question is moot now. Naim just replied they are not able to supply 'matched pairs' anymore. 

silklee posted:

Anyway, the question is moot now. Naim just replied they are not able to supply 'matched pairs' anymore. 

Precisely the same response to me when one of my tweeters called it a day a few weeks ago. although the other one seems still OK, i have decided to replace the pair anyhow so that at least they are 'age-matched'.  My SL2 are mid 2000's vintage -- what are yours? Could it be that c. 10yrs is expected life?

pity that matched pairs are not available anymore, but i guess that's the new world heh!

'where have the good times gone'? i think there is a song with this line in the lyrics?

enjoy(?)

ken

Ken 

Did you get your pair of tweeters from naim ?

Not sure if I am suppose to ask and say this here. The reason I am asking is that I can possibly find them for much cheaper than what I would have to pay my dealer. And if naim doesn't have matched pairs, and it's exactly the same tweeter I can get outside of naim, then it doesnt makes much sense to get from naim.

But I remember reading somewhere that naim adds some damping materials to the tweeter.

Anyway, I have to figure out if it's really a dead tweeter (hopefully maybe a cold joint somewhere) before I decide the next step forward. 

Hi Silklee -- yes i got my tweeters from Naim. Initially i ordered just the one to replace the errant one -- but decided to order another so i end up with an age-matched pair, or so i think. the 2nd one, i am told, has just been delivered to my dealer.

enjoy

ken

The tweeters in the SL2 are Scanspeak  2010/851300 a very old design and still widely available. 

Whizzkid posted:

The tweeters in the SL2 are Scanspeak  2010/851300 a very old design and still widely available. 

Surely they're the non-ferrofluid D2010/851100?

Willy.

Willy posted:

Whizzkid posted:

The tweeters in the SL2 are Scanspeak  2010/851300 a very old design and still widely available. 

Surely they're the non-ferrofluid D2010/851100?

Willy.

That's the one, I looked at the wrong page on the speakers spares sites they look identical and some say the ferrofluid one's increase performance dramatically, though not me I've never heard them and you are not allowed to talk about modifications on here.

I'd be careful about changing the type of tweeter. The fluid-filled ones have different characteristics & will alter the balance of the speaker. It'd be interesting to give it a try though...

My DBLs use the 2010/851300 & I've a couple of spares carefully stashed away. I wouldn't worry too much about the "Matched Pair" thing - Scanspeak build to pretty close tolerances & you really won't be able to hear any difference. If the tweeters are elderly then popping a single new one in will give a different sound so best to replace the pair.

ken c posted:

Precisely the same response to me when one of my tweeters called it a day a few weeks ago. although the other one seems still OK, i have decided to replace the pair anyhow so that at least they are 'age-matched'.  My SL2 are mid 2000's vintage -- what are yours? Could it be that c. 10yrs is expected life?

 

If it is the voice coils that have failed, which is indicated if it is a complete lack of sound, then there is no fixed 'life'', and they should last indefinitely unless overloaded - which could be a period of time listening very loud, but more commonly instantaneous damage caused by, for example, a high level 'pop' as can happen unplugging/plugging the inputs to the power amp when on, ditto sources when pre and power amps are on and volume control up, or switching sources on/off when connected and volume up, etc., or otgerwise an amp fault.

On the other hand, the flexible surrounds of the drive unit diaphragm can deteriorate with time, which can depend on the atmosphere where used, and change flexibility or even disintegrate, though this is usually only a problem with the much more flexible surrounds of mid and bass units.

My 30 yr old SP2s use the Scanspeak D2008/851300 (same diaphragm and motor as D2010/851300) and still show good measurements, with no significant rise in distortion.  So even with the ferrofluid cooled ones there's no fixed life expectancy.

This also shows the myth of ferrofluid 'evaporating' (which would cause a drop in output and an increase in distortion), at least in the case of the Scanspeak D2008 and D2010.  The grade of ferrofluid used in these tweeters is very high quality and very stable.

Over 45+ years, including experience with two pairs of speakers themselves approaching that age, I have encountered four drive unit problems, of which one was age-related.

1. Bass driver (KEF B139 racetrack) in one IMF RSPM speaker developed deformed voice coil resulting in scraping and distortion. Nothing to do with their near 40 year age at the time, but simply caused by a preamp going into oscillation on its MC input while playing at high volume.

2. Midrange units (Peerless KO40) in both of a pair of IMF TLS50 speakers had the cone surround deteriorate and go into holes after about 20 years, though no obvious effect on performance! I bought replacement surrounds and repaired them myself, and still OK some 20 years on from that.

3. Midrange unit in one of my PMC EB1i speakers (Vifa D75MX-41) damaged by a switch-off surge when I had Dave on home audition and turned it off forgetting to turn off power amp first or disconnect the speakers - one peril of using Dave without a preamp, as when I did have a preamp I always reduced the volume control to zero after use or before any source changes. The speaker developed distortion at about 600hz (fine above and below), causing a 'tizzy' sound to notes D5 & Eb5. Replacement readily available from both PMC (and online oem suppliers).

4. Supertweeter covering above 13kHz (Celestion HF2000) in one 45+ year old IMF RSPM speaker found when undertaking room setup testing to have lower output than the other and distortion at one frequency. Had not been evident with music and cause not known, though the speakers had been used many times at high volume levels, so overloading some time can't be ruled out. New original not available, so replaced both with a different but similar tweeter (Coles 4001).

Good to know there's someone else who's obsessive enough to use a mike and FFT to check their speakers (even if doing it in passing when doing room set-up testing!).

Innocent Bystander posted:

<snip>

3. Midrange unit in one of my PMC EB1i speakers (Vifa D75MX-41) damaged by a switch-off surge when I had Dave on home audition and turned it off forgetting to turn off power amp first or disconnect the speakers - one peril of using Dave without a preamp,
<snip>

Wow, that's a major design flaw, as DAVE's designed to work without a preamp.

For older Naim pre amps which use unbalanced +22V/+24V single rail supply (even if it's multiple +24V single rail supplies!) rather than balanced +/-15V power rails, this was inherent in the design, but it really shouldn't happen with more recent designs (e.g. 172 , 272, Hugo TT, DAVE etc).

(But having said that, just in case anyone thinks I'm suggesting otherwise:  Switching off the power amp first is still good practice.)

Huge posted:

Good to know there's someone else who's obsessive enough to use a mike and FFT to check their speakers (even if doing it in passing when doing room set-up testing!).

Yes, it was an interesting thing to do. Also (essential) using to adjust phase and tweak driver levels with a triamp trial.

A Hi-Fi manufacturer or dealer will of course want a mark-up, but if it's any good to you, the requisite driver is available for about £65 inc VAT from drive-unit supply companies in the UK.

Good luck.

John.

Huge posted:

Innocent Bystander posted:

<snip>

3. Midrange unit in one of my PMC EB1i speakers (Vifa D75MX-41) damaged by a switch-off surge when I had Dave on home audition and turned it off forgetting to turn off power amp first or disconnect the speakers - one peril of using Dave without a preamp,
<snip>

Wow, that's a major design flaw, as DAVE's designed to work without a preamp.

For older Naim pre amps which use unbalanced +22V/+24V single rail supply (even if it's multiple +24V single rail supplies!) rather than balanced +/-15V power rails, this was inherent in the design, but it really shouldn't happen with more recent designs (e.g. 172 , 272, Hugo TT, DAVE etc).

(But having said that, just in case anyone thinks I'm suggesting otherwise:  Switching off the power amp first is still good practice.)

It was a disturbing thing to be warned of in Dav's manual (reminds me of my very first power amp which hab significant  switch-on thump, which I soon resolved with a second switch (speaker isolator) manually operated a few seconds after the power switch, turn off in reverse.

it is only when powering on or off, normal use being to switch to standby - but that does notmake it any less of a potential problem. I put up with it for the sound benefit.

Huge posted:

Good to know there's someone else who's obsessive enough to use a mike and FFT to check their speakers (even if doing it in passing when doing room set-up testing!).

Presumably the remainder use their ears?

joerand posted:

Huge posted:

Good to know there's someone else who's obsessive enough to use a mike and FFT to check their speakers (even if doing it in passing when doing room set-up testing!).

Presumably the remainder use their ears?

Ah! that miracle of medical science, someone who can measure distortion in a 3-5kHz signal using just their ears.

No, the human ear can't necessarily identify a tweeter that's suffering from age related defects, even though it can still have an effect on music reproduction.

Huge posted:

joerand posted:

Huge posted:

Good to know there's someone else who's obsessive enough to use a mike and FFT to check their speakers (even if doing it in passing when doing room set-up testing!).

Presumably the remainder use their ears?

Ah! that miracle of medical science, someone who can measure distortion in a 3-5kHz signal using just their ears.

No, the human ear can't necessarily identify a tweeter that's suffering from age related defects, even though it can still have an effect on music reproduction.

In the case of my IMF supertweeter, I was completely unaware, and with my PMC midrange I only became aware when playing unaccompanied piano music, when there was the occasional 'tizz' - At first I just put it down to something I hadn't noticed before in the recording itself, then some days later I noticed it again on something different, that got me wondering, and I listened more, then tested it, when the fault was very obvious, and some simple diagnostic checks confirmed it was the mid driver.

An update. My very friendly dealer came over with his stuff and a pair of new tweeters. He confirmed that the tweeter is indeed dead. And he noticed that the dead tweeter has been changed before (the perils of buying second hand items). So I never had a matched pair to begin with.

When he was unsoldering the tweeter out, he noticed that it was really easy to 'cut off' the wires. Thus he suspects the reason why the tweeter died was due to 'arcing'.

Indeed when I first brought back the speakers, there was no sound from one of the tweeters. I shook the speaker a bit and the sound came back. So it could really be a poor soldering job resulting in arcing as I understand it.

I couldn't get a confirmation from Naim if the tweeters he had were indeed a matched pair (Naim needed a order number to confirm). However, the serial numbers on the 2 tweeters are close enough. In any case, he changed out both the tweeters and now, I have music again. And now I have a pair of spanking new tweeters. Happy!