KLH MODEL 5 RECAP Q'S

[Avpioneer]

So...this is a pretty novice question on my part but people here have been such a huge help so here I am to ask about replacing resistors. I've recapped the Model 17, 23 and 6 but have never replaced the resistors so far. I'm about to recap a Model 5 and it replacing the caps doesn't worry me but I DID have an open tweeter on one and wanted to ask whether or not resistors play into what could kill a tweeter. (used a model 23 replacement from an extra set I have so a lead on where to find another would be fantastic as well). I'll admit that I'm lazy and just don't want to replace everything in the crossover if it's not necessary.

If they start to fail, do they pass less through current through them, no current or more current? Basically asking "do failing resistors increase the chance of blowing tweeters?"

Is that a thing? How critical of a part do they play overall? My gatherings is that they are usually not replaced or rarely need replacing. Is that true in your experience?

Thanks in advance!

And for what it's worth 5 and 23's are magical and hard to decide between which ones I would call king. The 6's and 17's aren't getting sold either but I find myself not bothering with them lately for the main setup.

 

[toxcrusadr]

A resistor can drift up, or down, or open up completely. Which leads to less current, more current, and no current, respectively.

They are not usually in need of replacement, they don't wear out on the shelf like caps, but they can drift or get overheated.

I'd just check them with a meter and if they're within 10% and not burnt looking, you can leave them. Or they cost a buck so just replace them. But really only a meter will tell you.

 

[ra.ra]

There is a fellow who is very active on Classic Speaker Pages who has a great deal of experience with vintage KLH products, and his general practice is to replace the original resistors only for two reasons: 1) if there is obvious sign of damage, or 2) if they are rated at 5 watts, in which case he installs same resistance value but rated for 10 watts. He has shown several examples of burned 5W resistors.

 

[Avpioneer]

Do you think the resistors could play a part in tweeters blowing out? Or is it more about degradation of the overall sound if they are not within spec anymore?

 

[toxcrusadr]

It's possible, but also possible that the resistors are both fine and the tweeter burned up anyway. Resistors are there to reduce the volume on the driver, not to protect it from overdriving, and a power resistor is thermally more rugged than a tweeter voice coil, so it is not unusual to find what you have there and the resistors are OK.

I would be more concerned about them being out of spec in terms of the response curve being off. Too high and treble will be lower volume, too low and it will be boosted.

 

[audiojones]

It's very likely that the tweeter didn't actually burn out but rather the voice coil lead wire corroded through and broke open (which is very fixable BTW). When they soldered these together at the factory they didn't always clean the flux off very well and over the years it eats through the little tinsel wire under the mesh screen. I've posted a few threads on repairing them and there are others around here somewhere. If you do a bit of searching there should be some pretty good info around here.

 

[c5corvette]

^^^
This is more likely the cause of open tweeter. Bad resistor, possible, probably the tinsel wire. Tricky surgery to repair (solder), but worth a try.

 

[Avpioneer]

Ah, that’s why I come here, thanks for the info on the resistiets!

Btw, I ended opening the dead tweeter and took a look. Both wires above the cone are in one piece. No breaks. From other threads I’ve read, if they break below the surface...probably no way to resurrect it. I’ve got two others to check out that came out of some 6’s I bought a bit back so maybe I’ll luck out with one of those (though I understand they aren’t really the same as the 5, 12 and 23 tweets).