Speaker Life - Crossover Re-capping & Speaker replacement
A lot has been written on this forum about the re-capping of power supplies. Can anyone elaborate on the useful life of capacitors in speaker crossovers. I am currently contemplating replacing the galvanized steel spring clip speaker terminals (now just beginning to show signs of corrosion) on my Yamaha NS1000M monitors with some quality gold plated binding posts and was wandering whether I should replace the whole crossover unit or maybe the capacitors while I was about it. I was amazed to learn that spares for the Yamaha are still available and complete crossover units cost about £100 each.
I have had these speakers for nigh on 20years and am still quite happy with the sound. They are currently driven by a Naim 250 fed by a CDX/XPS, and a NAC 82 +2xHiCap. Speaker cables are Chord “Rumour” (NACA5 is impractical as the conduit I had installed is only 19mm) The speakers sitting on purpose designed alcove cabinet/shelf units approx. 450mm off the floor either side of a fireplace in my modest 12ft by 12.5ft Victorian listening room with 12 ft high ceiling.
For those of you unfamiliar with the NS1000M they are “infinite baffle” 3 way speakers with a 300mm bass unit and a “berillium dome” midrange. I think the tweeter is an aluminium dome. The drive units are all protected by nicely detailed wire mesh baskets and the whole thing looks purposeful and with no cables to trip over and taking up virtually no floor space has survived almost 20 years of growing children, inquisitive cats and “she who must be obeyed”
I visited Bristol thinking that soon I might need to replace the speakers. With no sign of Naim introducing a shelf mount, the Acoustic Energy AE2 was high on my list but alas no longer in production. The Dynaudio Contour 3.0 driven by the Naim 500 sounded somewhat similar but sadly I was not able to hear the Contour 1.3Mk11 which is the nearest bookshelf derivative that I could accommodate. The baby Epos did not seem to have the same punch I forget what was driving it. There was no sign of the B&W 805 anywhere. I have heard and liked the ATC SCM20SL but one really needs the active PRO versions to match the Yamaha for bass.
So with a fixed width space allocation of 380mm (height is adjustable) and maximum depth of 400 mm say does anyone want to suggest anything else I should listen to. Bear in mind that the back of the speaker will be tight against the rear wall. Speakers will be roughly 2 metres appart.
Now the problem gets really difficult. For domestic harmony the speakers sit on the same seriously heavy built in ash cabinet weighed down with books that the CDX and the electronics sit in. The CDX is currently isolated on “Audioquest” sorbothane feet. And the speakers are on cork tablemats. It seemed to make sense at the time and has given me much enjoyment over the years
I know I should move the electronics on to a Mana or Naim stand and have started to show her some pictures but until the cabinet holding the kids toys is dispensed with the real world situation is that speakers and CDX must cohabit. What is the best isolation strategy? Should it be spikes under the speakers and ball nuts under the CDX or what?
Posted on: 26 February 2001 by Andrew L. Weekes
Interesting question and one I've never considered.
The re-capping that Naim perform is primarily related to large value electrolytic decoupling capacitors, and the tantalums used for decoupling / coupling in some areas.
Speaker crossovers often contain non-polarised electrolytic capacitors, so there could be an argument for replacing these, any film type capacitors are likely to be OK and could be left unchanged.
Personally I'd look at changing them yourself, and considering trying some improved replacements, there are a number of large value film types generally available (e.g. Maplin) that could offer improved sound if physically compatible with the space available on your crossover (film capacitors are likely to be much larger than electrolytics). You'd need to experiment a little to see if you prefer the change.
The existing caps should have their values marked on them.
Andy.
Andrew L. Weekes
alweekes@audiophile.com
Posted on: 01 March 2001 by Eddie Pugh
Andrew
Thanks for your reply. No one else seems to be knowledgeable on the subject Not many guys out there seem to be interested in offering advice unless it directly concerns a Naim product.
According to the Yamaha NS1000M blurb the caps are long life self healing metalized paper. There are certainly lots of them 9 or 10 in all and they are very tightly packed on to a plastic carrier which also holds the spring clip terminals. I think I shall just change the terminals.
On your other forum topic of "speaker upgrades" I think you should consider the Dynaudio range. The little "Contours" are very impressive and perhaps the cheaper "Audience" might fit your brothers needs
Eddie
Posted on: 01 March 2001 by Fraser Hadden
Eddie,
Will you keep the forum posted if you do replace the capacitors? I think this is going to be one hell of a job, perhaps involving destruction of the backing plate as you struggle to extract the old caps.
I manage to use NACA5 cable with NS1000Ms by dint on an adapter which I hope does not degrade the sound too much as it is late in the chain conveying sound from source to speaker. I am onto my second pair of NS1000Ms now. I did replace the silly spring terminals with binding posts on my first pair, but the process was difficult enough to deter me from trying this a second time.
The treble units are beryllium domes too.
Fraser
Posted on: 01 March 2001 by Ron The Mon
Eddie,
If you go through the trouble of taking the caps out, go all the way and remove the crossovers from the cabinet. I've done this with several speakers and they always sound better. Simply put the crossover behind the speaker and hard-wire ala Naim to your speaker wire. It's easy to do and as you'd be changing plugs anyway, you'd just need to install two more. Depending on the space behind the speaker and the size of your conduit, you may be able to put the crossover closer to the amp(which I've found sounds better when using Naim wire).
Ron The Mon
P.S.
This also puts you one
step closer to active!!
Posted on: 01 March 2001 by wal riley
A small point, but a valid one, is that if you do remove the crossovers from the cabinets, make a note of the polarity of each individual driver and don't worry if the drivers appear to have been wired 'out of phase' with each other. It's not carelesness on Yamaha's part, but a consequence of a small time delay every crossover adds to a signal, as it passes through on the way to the respective driver. It's this delay that cocks up the now famous 'phase relationship' between the drivers, and an apparent reversal of phase on one drivers terminals is, in fact, just one way of bringing it back into line with the other speaker units in the cabinet, in order to preserve stereo imaging, accurate dispersion characteristics and an even tonal balance. By the way, Audiocom have some rather groovy film and foil caps. I use them in my home-made cabinets, but they're quite large, very heavy and cost around a tenner a go. Have fun!!!
