I am asked regularly about capacitors and when they need replacing. Here's my philosophy on the subject. It's more philosophy than science as I'm not an electronics expert but I do have a scientific background and I tend to apply observation and experience before forming a theory.
In my experience of listening to dozens of speakers over the years most don't urgently need the capacitors replacing. My advice has always been to listen and you'll know when something is wrong. It occurs to me that I will notice difference simply because I do listen to so many. When one is sounding wrong then often as not it is a faulty capacitor. But I know my system and my listening environment so changes are noticeable.
The practical problem is that capacitors last for ages and they deteriorate slowly. As they deteriorate their capacitance value changes gradually overtime. To put it simply the capacitors in a crossover set the crossover value/s and any change in the rated capacitance can therefore alter the frequency of the crossover point. Small changes are probably not noticeable, some of the original capacitors are only supposed to be accurate to 10% anyway, but a larger change will be noticeable.
But will it? When a change happens so slowly you get used to the difference in sound incrementally over time. So you lose the memory of what it is for the speaker to sound as it did when you bought it.
Some people are sensitive to this but most aren't. I stick to my general advice - if you're enjoying listening then leave well alone, it's the music that matters not the performance of the system in theory.
However those capacitors are now around 30 years old and they aren't going to last forever. I've been researching the subject for a while and recently rebuilt a couple of pairs of speakers for a customer who wanted to bring his speakers back to life. I changed all the capacitors I could for original replacements. They sounded a lot better to me afterwards.
This potentially causes a problem though, because they will certainly sound different. The question will be asked, are they better?
I know in this case that they will but if you think your capacitors are wearing out and get me to replace them then they may well come back sounding a bit different!
Another issue is which replacement capacitors to use. I'm aware that using new original replacements is something of a limited possibility as supplies are running out and costs rising as a result. I've been able to do it up to know and can still offer original replacements but a couple of the values are getting short so I've been looking further afield. There is also some debate about the shelf life of capacitors so that's another potential problem.
Here's a thing though - 30 years ago the electronic industry were making the best capacitors they could. 30 years on they must be making better ones surely?
I believe that they are and also (like cables) I know that some enthusiasts, I've been there, can spend hundreds on seeking a tiny improvement. I can offer fantastic capacitors at very expensive prices, for instance the Jantzen Silver Gold Z-Caps shown above are around £500! But that's not what most owners want. I think they want a good stable capacitor that doesn't contribute it's own sound to the system and can replace the original at a reasonable cost, so they can rely on their trusted favourite Celestions to keep giving them the listening pleasure they are used to. I'm looking at the sort of component that Celestion would've fitted back then - if they had been available.
So I have been buying capacitors, experimenting, listening and forming an opinion. It's driven me a little mad but now I am 100% happy that I can supply new very good quality reliable capacitors for a reasonable price which remain true to the originals and will deliver the traditional sound of the SL6 series.
I can also supply a better range at a premium price for those true audiophiles who want the best balance of price v. performance.
Or you can just go silly. I'd love to hear the Jantzen Silver Gold Z-Caps !
I rebuilt my bi-amped Sl600's with the standard quality caps (audiophile 3/5%) and they sound amazing, well worth the effort involved. I can heartily recommend this as an upgrade.
For SL6 -
DiY change of capacitors is £37.50 incl. postage in the UK
Change for new polycap replacements (crossovers only or DiY) is £47.50 incl. UK postage
Change of capacitors for new premium quality (crossovers only or DiY) is £68 incl. postage in the UK
Change of capacitors for new top quality (crossovers sent only) is up to £180 incl. postage in the UK
For SL6S/Si -
DiY change of capacitors (250/400v, 3/5%) is £27.50 incl. postage in the UK
Change for new polycap replacements 250/400v 3/5% (crossovers only or DiY) is £37.50 incl. UK postage
Important -
Never unsolder tweeters at the tweeter end of all SL6 models, always unsolder at the crossover, otherwise you will be likely to unsolder the signal wires, and it's a hell of a job to resolder them.
The use of a hot melt glue gun to fix the capacitors to the crossover board is advised, but not essential, but they are handy things to have and can be bought for a couple of quid.
Please note that a 6mfd capacitor is no longer available and so is replaced with a 5.6 mfd.
1.5mfd are not available in 3% so are always 5%
Capacitors are in short supply since the pandemic and if I cannot source 4oov 3% then sometimes I have to use 250v or 400v 5% ones in custom sets. You will always be made aware of this before ordering.
For the standard SL6S/Si kit assume 250v 5%, but I am negotiating to try to get the 400v ones for the same price!
Feel free to enquire and exchange information. I'm not able to give a set price for other than the SL6/S/Si. I have come across varying crossovers from other models in the 'SL6' range so I cannot tell what you have until you tell me, or I get the crossovers from you! I can also quote for any specific type of capacitor you would like.
In my experience of listening to dozens of speakers over the years most don't urgently need the capacitors replacing. My advice has always been to listen and you'll know when something is wrong. It occurs to me that I will notice difference simply because I do listen to so many. When one is sounding wrong then often as not it is a faulty capacitor. But I know my system and my listening environment so changes are noticeable.
The practical problem is that capacitors last for ages and they deteriorate slowly. As they deteriorate their capacitance value changes gradually overtime. To put it simply the capacitors in a crossover set the crossover value/s and any change in the rated capacitance can therefore alter the frequency of the crossover point. Small changes are probably not noticeable, some of the original capacitors are only supposed to be accurate to 10% anyway, but a larger change will be noticeable.
But will it? When a change happens so slowly you get used to the difference in sound incrementally over time. So you lose the memory of what it is for the speaker to sound as it did when you bought it.
Some people are sensitive to this but most aren't. I stick to my general advice - if you're enjoying listening then leave well alone, it's the music that matters not the performance of the system in theory.
However those capacitors are now around 30 years old and they aren't going to last forever. I've been researching the subject for a while and recently rebuilt a couple of pairs of speakers for a customer who wanted to bring his speakers back to life. I changed all the capacitors I could for original replacements. They sounded a lot better to me afterwards.
This potentially causes a problem though, because they will certainly sound different. The question will be asked, are they better?
I know in this case that they will but if you think your capacitors are wearing out and get me to replace them then they may well come back sounding a bit different!
Another issue is which replacement capacitors to use. I'm aware that using new original replacements is something of a limited possibility as supplies are running out and costs rising as a result. I've been able to do it up to know and can still offer original replacements but a couple of the values are getting short so I've been looking further afield. There is also some debate about the shelf life of capacitors so that's another potential problem.
Here's a thing though - 30 years ago the electronic industry were making the best capacitors they could. 30 years on they must be making better ones surely?
I believe that they are and also (like cables) I know that some enthusiasts, I've been there, can spend hundreds on seeking a tiny improvement. I can offer fantastic capacitors at very expensive prices, for instance the Jantzen Silver Gold Z-Caps shown above are around £500! But that's not what most owners want. I think they want a good stable capacitor that doesn't contribute it's own sound to the system and can replace the original at a reasonable cost, so they can rely on their trusted favourite Celestions to keep giving them the listening pleasure they are used to. I'm looking at the sort of component that Celestion would've fitted back then - if they had been available.
So I have been buying capacitors, experimenting, listening and forming an opinion. It's driven me a little mad but now I am 100% happy that I can supply new very good quality reliable capacitors for a reasonable price which remain true to the originals and will deliver the traditional sound of the SL6 series.
I can also supply a better range at a premium price for those true audiophiles who want the best balance of price v. performance.
Or you can just go silly. I'd love to hear the Jantzen Silver Gold Z-Caps !
I rebuilt my bi-amped Sl600's with the standard quality caps (audiophile 3/5%) and they sound amazing, well worth the effort involved. I can heartily recommend this as an upgrade.
For SL6 -
DiY change of capacitors is £37.50 incl. postage in the UK
Change for new polycap replacements (crossovers only or DiY) is £47.50 incl. UK postage
Change of capacitors for new premium quality (crossovers only or DiY) is £68 incl. postage in the UK
Change of capacitors for new top quality (crossovers sent only) is up to £180 incl. postage in the UK
For SL6S/Si -
DiY change of capacitors (250/400v, 3/5%) is £27.50 incl. postage in the UK
Change for new polycap replacements 250/400v 3/5% (crossovers only or DiY) is £37.50 incl. UK postage
Important -
Never unsolder tweeters at the tweeter end of all SL6 models, always unsolder at the crossover, otherwise you will be likely to unsolder the signal wires, and it's a hell of a job to resolder them.
The use of a hot melt glue gun to fix the capacitors to the crossover board is advised, but not essential, but they are handy things to have and can be bought for a couple of quid.
Please note that a 6mfd capacitor is no longer available and so is replaced with a 5.6 mfd.
1.5mfd are not available in 3% so are always 5%
Capacitors are in short supply since the pandemic and if I cannot source 4oov 3% then sometimes I have to use 250v or 400v 5% ones in custom sets. You will always be made aware of this before ordering.
For the standard SL6S/Si kit assume 250v 5%, but I am negotiating to try to get the 400v ones for the same price!
Feel free to enquire and exchange information. I'm not able to give a set price for other than the SL6/S/Si. I have come across varying crossovers from other models in the 'SL6' range so I cannot tell what you have until you tell me, or I get the crossovers from you! I can also quote for any specific type of capacitor you would like.