KLH Crossover Failure Questions

[Guest eckerman]

Hello,

I have 6 pair of KLH Model Six Speakers - each in a different room in my house. 2 are of the earlier epoxy production; 4 have the velcro grills with the speakers screwed in. All sound great; no problems - "knock on the wood cabinets." The tweeter high-ends all are bright and loud.

Nevertheless, I am aware (from posts in various forums) of the problems with the crossovers failing. I have some questions about this failure, if someone knows:

i) Does the crossover failure occur suddenly, or is it gradual?

ii) Is the failure more likely to occur in the older, epoxied speakers?

iii) Is there anything that exacerbates the failure, such as playing the speakers loudly, or is it just age?

Thanks for comments.

Dale

Boston

[Andy]

Crossover failure usually is gradual and happens with time. If the speakers sound good to you, I'd leave them be. Many folks on the forum say upgrading the crossovers is the way to go. The early model Sixes had oil filled caps, not the paper ones and they should last for a very long time. My 1958 model Sixes are all original and sound perfect. Warning;.....if you try to change them on the epoxied versions, you'll have a heck of a time getting into the cabinet.

All of my KLH speakers are original and all still sound exellent, so for now I'm leaving them alone!

[Guest eckerman]

Thanks, Andy. for your insights.

At the present time, all of my tweeters are bright and loud for the high-end sounds. Of course, I have no scientific way to measure this. Perhaps they are deteriorating a bit at a time - such that I wouldn't notice the gradual degradation? Can someone describe the point at which I would know that the crossover wasn't working properly?

Although crossover failure may be the "achilles heal" of the aging Model Sixes, perhaps, and hopefully, the crossover failure is not as widespread as some of the posts would suggest. I think that there are many active Model Six owners with no crossover failures. Does anyone have an idea about the prevalence of this failure?

Is there anything that exacerbates the failure, such as playing the speakers loudly, or is it just age and luck of the draw?

I appreciate any comments.

Dale

Boston

[tysontom]

Andy,

Do you know what year, and at what approximate serial-number sequence, KLH stopped using oil-filled capacitors and went to conventional caps? I know that the epoxy-driver Model Sixes had both oil-filled and conventional cap versions.

Thanks,

--Tom Tyson

[Andy]

Tom,

I do not know at what serial number or date the change to paper capacitors was made. Poduction of the epoxied-in model Sixes went as high as serial numbers 94,000 as I'v read on previuous posts in this forum. That would be in the 1964-65 period.

Also, a few years ago there was a post about the PCB danger involved with the production of oil fill capacitors, but I couldn't find it in my search. If I remember correctly, it mentioned a Government report citing the PCB danger....late 1963 ? The rusult was the speaker industry changing over to paper caps in a short period of time. I would think it was very close to the time AR made the change. Tom, you may have the details as to AR's capacitor history.