I have a KEF Reference Model 90 center channel, and a pair of KEF Q1 near field monitors that I picked up used. It turns out the electrolytics on the crossovers of all 3 speakers are shot, so I need to find replacements. I need to find a good supplier for small quantities of electrolytic non-polarized capacitors at a fair price.
I figured since many of you are speaker builders you probably have decent sources for crossover components.
The ones I specifically need are:
Radial N.P.
2x 50V 8μF ±10%
2x 50V 8.2μF
2x 100V 14μF
axial N.P.
1x 50V 10μF
1x 50V 60μF
1x 50V 4.2μF
1x 50V 12μF
If you have a source for higher tolerances, that'd be even better (5%)
Thank you for any help anyone can offer.
I figured since many of you are speaker builders you probably have decent sources for crossover components.
The ones I specifically need are:
Radial N.P.
2x 50V 8μF ±10%
2x 50V 8.2μF
2x 100V 14μF
axial N.P.
1x 50V 10μF
1x 50V 60μF
1x 50V 4.2μF
1x 50V 12μF
If you have a source for higher tolerances, that'd be even better (5%)
Thank you for any help anyone can offer.
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This from Steve AKA system7 might be of interest to you.
http://www.diyaudio.com/forums/multi-way/213216-x-over-kef-iq30-2.html#post3041198
http://www.diyaudio.com/forums/multi-way/213216-x-over-kef-iq30-2.html#post3041198
Bi-polar sounds like slightly crazy. I think the words you want are non-polar electrolytic to replace dried-up originals:
NON POLAR ELECTROLYTIC CAPACITORS from Parts Express ship same day and come with 45 day money back guarantee. Free Shipping Available. Order free 10,000 product catalog.
You parallel appropriate values to make up awkward numbers, so for instance a 10uF parallel with a 4.7uF makes 14.7uF. Near enough to 15uF for any purpose I can think of. In fact electrolytics are very rough and ready on value and wander. 10% is as good as it gets really. Where a 50V is specified, 100V will be even more rugged, so do fine. Polypropylenes are nice but rather huge above 3.3uF.
I would just bend the leads on an axial capacitor to get it to fit in a radial position. Really doesn't matter.
NON POLAR ELECTROLYTIC CAPACITORS from Parts Express ship same day and come with 45 day money back guarantee. Free Shipping Available. Order free 10,000 product catalog.
You parallel appropriate values to make up awkward numbers, so for instance a 10uF parallel with a 4.7uF makes 14.7uF. Near enough to 15uF for any purpose I can think of. In fact electrolytics are very rough and ready on value and wander. 10% is as good as it gets really. Where a 50V is specified, 100V will be even more rugged, so do fine. Polypropylenes are nice but rather huge above 3.3uF.
I would just bend the leads on an axial capacitor to get it to fit in a radial position. Really doesn't matter.
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bi-polar, non-polarized, N.P., B.P., etc.. same thing. I've seen them listed as all of the above.
I'm aware of how to combine capacitors, however, the problem I'm having is finding them in Radial or Axial lead packages as listed above to fit the boards where I'm replacing the existing caps. A bit of size difference isn't an issue, but having one lead coming out of the wrong end of the cap is a problem. I've seen a lot of 5% and even higher-tolerance audio grade capacitors, but I can settle for 10$ if they are available in matched pairs, since I'm rebuilding the crossovers in both speakers. Since I'm trying to keep this crossover as a low noice circuit, I'd prefer not to have leads that are two or three inches long and running the length of the capacitors if it can be avoided. If not, I'll have to make due.
If this works out, I'll probably recap both pair of 104/2s that I have as well.
I'm aware of how to combine capacitors, however, the problem I'm having is finding them in Radial or Axial lead packages as listed above to fit the boards where I'm replacing the existing caps. A bit of size difference isn't an issue, but having one lead coming out of the wrong end of the cap is a problem. I've seen a lot of 5% and even higher-tolerance audio grade capacitors, but I can settle for 10$ if they are available in matched pairs, since I'm rebuilding the crossovers in both speakers. Since I'm trying to keep this crossover as a low noice circuit, I'd prefer not to have leads that are two or three inches long and running the length of the capacitors if it can be avoided. If not, I'll have to make due.
If this works out, I'll probably recap both pair of 104/2s that I have as well.
I really wouldn't lose any sleep over 2" of lead on fitting an axial in a radial position. Best technique is to put the short lead to earth, or the outer braid to earth with a coil to avoid radio interference.
My old Professor always said that component tolerances only affect -3dB crossover point, not the pass band. If you can hear 10% difference, I'd be surprised.
FWIW, when you replace an electrolytic (ESR=5%) with a better polypropylene, some positions in the circuit can end up underdamped. The woofer shunt capacitor is very sensitive to this and you might add a 0.5 ohm resistor. Other parts like tweeter filters less so.
Have a bash, mate. It'll work.
My old Professor always said that component tolerances only affect -3dB crossover point, not the pass band. If you can hear 10% difference, I'd be surprised.
FWIW, when you replace an electrolytic (ESR=5%) with a better polypropylene, some positions in the circuit can end up underdamped. The woofer shunt capacitor is very sensitive to this and you might add a 0.5 ohm resistor. Other parts like tweeter filters less so.
Have a bash, mate. It'll work.
I found what I needed on P-E. I used a combination of NP electrolytics and a metalized poly or two for the values I couldn't do in the NPE caps.. namely due to space constraints with the radial lead caps (they're packed close together)
Total cost to re-cap the XOs in 3 separate speakers? $18 shipped.
When I re-cap the main speakers (104/2s) and my amplifiers, I'll probably go with 1% poly caps and black gate electrolytics. Those are things I'm more worried about accuracy with, and less worried about cost.
These were yardsale finds, and I don't want to sink a load into restoring them.. haha
Thanks for the help and suggestions.
Total cost to re-cap the XOs in 3 separate speakers? $18 shipped.
When I re-cap the main speakers (104/2s) and my amplifiers, I'll probably go with 1% poly caps and black gate electrolytics. Those are things I'm more worried about accuracy with, and less worried about cost.
These were yardsale finds, and I don't want to sink a load into restoring them.. haha
Thanks for the help and suggestions.
Hi,
FWIW sometimes tolerances can be deceptive regarding standard values
and the real values in a crossover. If you want to select say 6uF to 3%*,
your better off selecting from a batch of 6.2uF 10% capacitors than 5%,
AFAIK e.g. typical bipolars were only made to 10%, and then selected.
Falcon Acoustics used to do it, for the crossovers they made for a lot
of British companies, the tolerance on the capacitors didn't reflect the
tolerance used, or value the actual best capacitor value for the x/o.
Of course this is only for the more expensiive x/o's. but you get the
jist. Same way as all KEF Constructor drivers were effectively rejects.
KEF designed different models that used the same driver to use drivers
from different parts of the bell curve of production spread. What was
left over they sold in their speaker kits - somewhat cynical I'd say.
rgds, sreten.
FWIW sometimes tolerances can be deceptive regarding standard values
and the real values in a crossover. If you want to select say 6uF to 3%*,
your better off selecting from a batch of 6.2uF 10% capacitors than 5%,
AFAIK e.g. typical bipolars were only made to 10%, and then selected.
Falcon Acoustics used to do it, for the crossovers they made for a lot
of British companies, the tolerance on the capacitors didn't reflect the
tolerance used, or value the actual best capacitor value for the x/o.
Of course this is only for the more expensiive x/o's. but you get the
jist. Same way as all KEF Constructor drivers were effectively rejects.
KEF designed different models that used the same driver to use drivers
from different parts of the bell curve of production spread. What was
left over they sold in their speaker kits - somewhat cynical I'd say.
rgds, sreten.
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That's pretty amusing. I know KEF designs and makes their own drivers, unlike a lot of companies that buy from one of the big 3 speaker houses and build their cabinets with rebranded drivers, but I've always owned Reference series speakers from KEF, and I know with the 104/2s at least, the components for the XOs were always matched pairs so the tolerances between speaker serial number xxxA and xxxB were closely matched, which if I re-cap mine, I'll probably go from the original electrolytics to some Dayton 1% metalized poly caps instead, for longevity as well as accuracy, since I order on-line and don't have the luxury of going through the whole bin with an ESR meter, or even through a large batch of product to find closely matched pairs for the project. That's one small drawback to the internet now, versus the old days when you could go to a parts shop and fish through the bins for what you wanted, but I can live with that.
I know the 104/2 XO is rather complicated as well, so I have to be careful when messing with it not to change anything too drastically. Those XOs were designed to present a flat resistive load, and they're anything but simple.
These KEF Q1 monitors are the first non-Ref models I've actually owned, and I believe some of the bits for them were actually made in China as opposed to Maidstone, which was slightly disappointing.
I know the 104/2 XO is rather complicated as well, so I have to be careful when messing with it not to change anything too drastically. Those XOs were designed to present a flat resistive load, and they're anything but simple.
These KEF Q1 monitors are the first non-Ref models I've actually owned, and I believe some of the bits for them were actually made in China as opposed to Maidstone, which was slightly disappointing.
Have you checked at Parts Express?
http://www.parts-express.com/non-polarized-electrolytic-capacitors.cfm
http://www.parts-express.com/non-polarized-electrolytic-capacitors.cfm
yeah P-E is where I ended up ordering the ones I needed. Thanks.
They didn't quite have everything I needed, but I made due with what they did have. They lacked an NP elect. 60uF 100V cap, so I used a poly cap in it's place with the proper value.
The rest they had, or I made with a combination of smaller values.
They didn't quite have everything I needed, but I made due with what they did have. They lacked an NP elect. 60uF 100V cap, so I used a poly cap in it's place with the proper value.
The rest they had, or I made with a combination of smaller values.
FWIW, when you replace an electrolytic (ESR=5%) with a better polypropylene, some positions in the circuit can end up underdamped. The woofer shunt capacitor is very sensitive to this and you might add a 0.5 ohm resistor. Other parts like tweeter filters less so.
Have a bash, mate. It'll work.
Just make sure you take note of this comment from syetem7 with respect to your 60uF cap. It may not matter at all, but you can get some pretty severe peaking if there is not enough damping due to esr in the woofers shunt cap.
Tony.
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