PXX or SAX for crossovers?

[John7]

Hi to all,

Which caps from WD should I use as replacements in crossovers in a large 3-way speaker? I'm looking at 3.3uF, 4.7uF plus if I replace them all 35uF, 40uF and 80uF

I think the smaller ones are for the treble. The others?

I won't touch the resistors or inductors ...

Or are there any better?

On a related matter, is there an easy way to solder quite thick internal cable to tiny pins on the PCB?

John

[Brian]

Originally Posted by John7

Hi to all,

Which caps from WD should I use as replacements in crossovers in a large 3-way speaker? I'm looking at 3.3uF, 4.7uF plus if I replace them all 35uF, 40uF and 80uF

I think the smaller ones are for the treble. The others?

I won't touch the resistors or inductors ...

Or are there any better?

On a related matter, is there an easy way to solder quite thick internal cable to tiny pins on the PCB?

John

Can you post the circuit?

[Richard]

Hi John,

Yes, we could have a look at the circ but I'd guess the first 2 are in the series feed to the tweeter, the second 2 are series in the mid (is there another as shunt, 3 in all, for the mid?) and the big one will be shunt for the bass.

I've done this, changing out Alcap paper caps in 3 way speakers, and they all make a difference but probably it's more noticeable in the tweeters, though doing the bass did bring more resolution there too.

It really depends on how hard you want to go in on this, whether to do the lot in one go or dip a toe and see what you think.

I'd be tempted to go the latter route and change just the tweeter caps first. These usually make most difference, are cheaper, and easier to try. Either SAX or PPX will be fine, I'd personally try PPX, I've used SAX before in an app where there was such a choice and actually found the cheaper PPX sounded better and both are a superior dilectric to paper in electrical terms. It might not be the same here of course but you've got to start somewhere so start cheap as you don't need the voltage rating you'd be paying for with the expensive ones.

This all said, I've changed speakers since then and have resisted temptation to play with the new ones. It would be easy enough to do but I'm happy with them so won't disturb a good recipe (yet!). Try to save any parts you take out and be honest with yourself so that you might refit them if the new caps aren't an improvement. Bear in mind that, yes, they may be better electrically but the speakers will have been "voiced" with the existing caps and to get an overall improvement using "better" caps it may need a small tweak to some xover electrical values. For example, I found more detail but it was along with higher level for that driver. It wasn't a problem as I could attenuate the drivers individually but if you can't you may then find the speakers tiring or unbalanced.

[John7]

Hi Brian, Richard

Can't post the circuit at the moment ... I'd have to dismantle the speakers and they are currently my main pair!

I will probably use the PXX caps to replace just the two 4.7uF and the 3.3uF, as they are not very much bigger than the Elcap (?) already on the PCB. Any 35, 40 or 80uF I have found online have been enormous!

I don't have the expertise to completely re-do the crossovers, so the smaller caps it is ...

I have to ask again - Is there an easy way to solder thick internal wires to small pins on PCB? I don't really want to take them out ...

One thing I haven't mentioned is that these are really old speakers. Any component change will benefit them, yes?

John

[Richard]

It may improve them if the original caps have changed value. You hear about this but I have a meter and every one I've changed (some 30 years old) have still been fine. They will most likely sound different so that just depends then on what you're trying to achieve.

I find it easiest to solder wire ends directly to a suitably large part of the pcb track itself rather than trying to use existing holes or pins. Carefully soldered joints both ends may well be better than old tarnished tags but don't expect a couple of feet of wire to make a lot of difference, that is, I wouldn't trouble with very large wire.

[John7]

Originally Posted by Richard

It may improve them if the original caps have changed value. You hear about this but I have a meter and every one I've changed (some 30 years old) have still been fine. They will most likely sound different so that just depends then on what you're trying to achieve.

I find it easiest to solder wire ends directly to a suitably large part of the pcb track itself rather than trying to use existing holes or pins. Carefully soldered joints both ends may well be better than old tarnished tags but don't expect a couple of feet of wire to make a lot of difference, that is, I wouldn't trouble with very large wire.

Hi Richard,

Thank you for the tip on soldering the wires. Why didn't I think of that?

The original caps are over 30 years old, so I expect some have changed value! Speakers don't sound bad though, but don't quite have the same 'spark' as they did. I'll spend a few quid on the crossover and wiring and see how they sound then. I won't get Nordost Valhalla for the internal wire

I know at the back of my mind, that I'll eventually get some WD25Ts ...

John