Lifespan of Speaker Drive Units

Dear Paul,

The caps in the x overs will deteriorate with age, so will need replacing.

The surround of the speaker will age and its compliance will change over time changing its performance and thus sound quality.

The spider will change its flexural characteristics over time as well.

The diaphragm will age as well and will either stiffen and harden or become lossy and flexible.

So in all it s a mechanical system with many variables. trouble is new drive units will more than likely be different to old ones so will sound different anyway.

Why not look at a different loudspeaker as an alternative.

regards David

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Why not look at a different loudspeaker as an alternative

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Quite simply because the only alternative in an active SBL system that I have would be SL2s. My experience with the SL2s has been less than stellar for a speaker twice the cost of the SBLs! NBLs, at an even higher cost, are probably the route for me to take (or DBLs for that matter) but that would require an additional power amp and a new SNAXO as well. Cost for NBL/250/SNAXO/A5 = a significant sum far greater than replacing SBL drivers. No doubt, it would be better and some day I may go that route but for now I intend to stick with my SBLs.

So then, if drivers do deteriorate should they be replaced after 10 years or...?

Paul

10 years aren't a problem.

20 years might be, particularly if the drivers have a foam surround.

If you want new foam grills for sbls they will cost you about £75 for all four bits.

However Sheila from Naim tells me they are washable though!!

Tim

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Originally posted by Timbo:
If you want new foam grills for sbls they will cost you about £75 for all four bits.

However Sheila from Naim tells me they are washable though!!

Tim

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I think the above were referring to the flexible foam surrounding the paper of the driver cone....... Not the foam that sticks on the front of the speaker to cover the drivers...........

Computers are supposed to work on 1's and 0's - in other words "Yes" or "No" - why does mine frequently say "Maybe"?......

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The caps in the x overs will deteriorate with age, so will need replacing.

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It's amazing how many definitive statements are made here, that are obviously not completely true

If the cap's in your speakers are non-polar electrolytic types, they will degrade with time, dependant upon listening levels (i.e. power delivered to speaker) and time.

The film caps, used in high quality crossovers (and this includes every Naim speaker that I'm aware of) will NOT degrade with time, simply because there is no wear-out mechanism (i.e. electrolyte loss / use).

Andy.

I think this is a fascinating topic and one worthy of further discussion. While I've seen many 1970's-80's vintage speakers with rotted out foam surrounds, recent experiences have shown that non-foam designs may last much longer than expected. These encounters with vintage speakers suggest that speakers can last, and sound quite good, a long, long time.

A couple of months ago I picked up a pair of 1960's-'70's vintage KLH acoustic suspension speakers. These are BIG speakers with lovely veneers. They seem to work fine though I've been delayed in assembling the second system where I plan to use them. Their surrounds are not rotted at all though the sealant used in their assembly may be dried out. I've found instructions on the internet for repairing them, should it be necessary but there is no "rot" that I can see.

Just last week I had the fun of resurrecting a late 1960's pair of Tannoy's in my brothers system. These things kick ass! No way to take off the grills but the sonics are superb.

Lastly, I picked up a single 1950's vintage JB Lansing 15 inch woofer. One with an alnico magnet. The paper cone is broken due to someone's carelessness but if not for that the thick paper cone looks like it would work fine. There does not appear to be any rot anywhere on the cone.

Markus

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[This message was edited by Markus on FRIDAY 27 June 2003 at 14:13.]

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My AR94s from the 80s lasted 6 years (conveniently outside AR's warranty period) before the foam perished. Apparently, living in high humidity conditions isn't all that good for foam.

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Humidity enter into the equation to be sure, but 6 years, whoa!
My Dad's set of AR3a bought in the mid 70s didn't need refoaming until the early 90s.

Drive units have been made with so many different materials that one cannot make general statements or be definitive about how long they will maintain a good performance.

I have a fairly large collection of KEF speakers and drive units from the 70s and late 60s and they are all in excellent condition except a pair of early BD139s which are ABRs found in Cadenzas. The foam has disintegrated. In later BD139s the foam was replaced by rubber and examples of these are perfect.

Drive units with paper cones are unlikely to have maintained their performance over the same period.

Terry

While I can't speak to technical issues or the effect of environment in all cases, I do regularly have a run in with some old speakers that seem to be doing just fine. My local classical CD specialist retailer uses a pair of huge, ancient speakers - well, maybe not ancient, but I'd say at least 25 years old - to pump music into the shop. (I don't know what brand or model they are. Neither do the shop employees!) They are in use at moderate sound levels 10-12 hours a day, 363 days a year, and have been since the shop opened. They still sound pretty good. (And they can put out prodigious bass if required.) So at least some speakers can last a long time. I'd say if a speaker begins to show wear in less than a decade, they're probably not up to spec. (Extremely humid climates seem to offer a challenge, though.)

I bought a pair of Spendor BC1s in 1972, in 1983 I had to have the drivers replaced because the bass units had suffered from cone sag due to the mild humidity and lack of air conditioning in the UK.

Spendor replaced the whole baffle board, the drivers and crossover and essentially upgraded to the later variant of the BC1 - the bass driver was a paper based driver (from what I remember)

The symptons of cone sage were a grating/rubbing noise on low notes.

Derek

<<Have you checked your PTs today>>

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Originally posted by James:
Terry,

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Drive units with paper cones are unlikely to have maintained their performance over the same period.

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Not sure where you get your 'facts' from, but I've yet to hear about a worn paper cone. That uncoated cones can soften in humid condition is true (but that is reversible when taken into a drier environment), but a good quality coated paper cone last pretty much forever under most conditions.

James

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Yes of course there is always a problem with generalisations and I am sure that there are lots of examples of drive units with paper diaphrams which are still working well. I was really comparing paper vs plastic as the KEF diaphrams from the 70s were manufactured from plastics expept in the case of the larger KEF units in which metal and plastic were used. Plastics give less variation in performance due to changes in temperature and humidity, and less physical and chemical deterioration with age.
Terry

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Originally posted by James:
Terry,
No disagreement about the longevity of plastics, but regretably most of them sound like crap.
James

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James
I suspected that someone would make such a comment and that is why I quoted directly from a KEF brochure which you may like to view. All owners of LS3/5a speakers, Linn Isobariks and many other speakers which use the B110 drive units may wish to disagree. There are of course many speakers with plastic diaphragms which are as you suggest of lower quality. Of course many poor quality paper diaphragm drive units were also made. Not a good idea to generalise.
Terry

[This message was edited by plynnplynn on MONDAY 30 June 2003 at 21:20.]

One nice thing about older speakers is that they can have the honest, not-fovoring-anything sound that only a *fully* run-in speaker can have. Its like old shoes that have molded to your feet. The new ones just don't feel quite right.

Missing from this discussion seems to be the difference between woofers and tweeters. The forum has had several posts/threads from people who replaced tweeters to great effect. In many cases, it was not an upgrade to the tweeter but just replacing what was there.

Any thoughts on the lifespan of tweeters (excepting blowing them out of course)?

- GregB

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