GETTING READY TO REPLACE DIAPHRAM IN HERESY II

[jeffgeorge]

Two questions:

1. I have seen many posts on the board in regards to replacing diaphrams on a K-77 tweeter. These seem to involve soldering. I took the old, presumably blown, diaphram (from my K-76-K) out tonight and found that there does not seem to be any soldering involved... true? - My new diaphrams arrive tomorrow.

2. Does anyone have any tips as to what I should, or should not do, while replacing the diaphram?

[BEC]

You are correct. No soldering is required on the K-76K tweeter. I would, however, make sure the magnet gap (where the voice coil goes) is cleaned out good. I usually use a sticky note and fold it so that the sticky part is on the front and back. I run this around the magnet gap until I can't get anything else out of it.

Bob

[WMcD]

Yes,

I changed out two tweeter diaphragms on my eBay Quartets. Like a dummy, I took only a few pictures and did not put together a tutorial. I really wanted to hear them.

I'll tell you what I did. You'll have to see what you have and see how much of what I did applies to you.

It a bit more complicated than changing a lightbulb. Not much more. The first time just deserves a measured, calm approach. Plan to take an hour. You'll probably take much less. There are no extra points for speed.

My tweeter was front mounted. This means you just have to back out the screws. Mine were Philips head. I've read some Klipsch have Torx. They are star shaped. These are common in computers. So if you have that and don't have a Torx driver of the proper size, check with some computer friends.

On my Quartets, there was a gasket just behind the rim of the tweeter. Not very fragile, but ya never know how much yours might have aged. If it stuck to the box or the driver, let it stay there where it is happy.

My tweeter had push on connections. Of course you'll have to slip them off. If they are firmly on there it makes sense to take a small pair of pliers and grasp the brass end and pull, rather than pulling on the wire.

Make some notes on what color wire goes where. You'll probably find a black to ground. There is a little (-) and (+) cast into the on the tweeter.

There is some chance that the disconnected wires will fall back into the box if you don't tape them to the face of the box.

But now you should have the tweeter free. I moved into the kitchen where there is a good counter and lighting.

Take a look in your shipment. I found an instruction sheet which was the product of something recopied several times. But readable. It looks like the same diaphragm is used on dozens of neo-Heritage units.

You'll see that the tweeter is a three part sandwich. Magnet structure, diaphragm assembly, and horn. There are three bolts and nuts holding it together. This is shown in the instruction sheet to some extent in cross section.

For good or bad, your voice coil is already damaged so you're not going to hurt anything taking it apart after you back off the nuts and take it apart.

The instructions I have say to check the ring shaped gap for debris. The sticky side of masking tape can be used to clean it out.

Basically, now you can compare the new diaphragm assembly and the old. You'll see the very thin cylinder of wire glued to the dome shaped diaphragm. That is the fragile part. It is what goes in the magnet gap.

The following may be important because it is not mentioned in the instructions: I found a button of fiber in my old diaphragm behind the dome and there was nothing similar in the replacement. So I used some tweezers to move it from the old to the new.

Yours may or may not have that.

So now all you have to do is place the new diaphragm assembly over the little bolts and snug up the nuts. I used some pliers to do this. It would have been better if I had the proper sized small wrench on hand.

Of course you have to use some judgment on how much to tighten. "Medium-snug and not forced" is my best advice. You'll get a feel for this in the process of backing off the nuts in the first place.

The rest of the project is just to reconnect the wires (refer to your notes on which goes where) position the gasket (if necessary) and insert the mounting screws which hold the tweeter to the box.

My Quartets have a board made of MDF. MDF has little strength. So you have to be careful not to overtighten and strip out what threads there are in this "economical" (ahem) material.

But that is about all there is to it. If you have questions, please do not hesitate to ask.

Also, should you have a digital camera, it would benefit others if you make a record.

Best,

Gil

[jeffgeorge]

Thanks BEC and Gil,

It sounds like I am on the right track. Gil, I will try to photographically document my surgery on these tweeters, so that others may benefit. I am just hoping that it is my tweeter that is blown and not something in the crossover.

I hope to see you guys in Indy in three weeks. Can't wait.