BEC

You should take both of the horns and drivers out the front to determine polarity. The midrange should have a white or yellow paint dot near the positive terminal. The tweeter has a "+" stamped into the plastic near the positive terminal. Bob Crites

Do you have any test results to verify this. The CF-4 crossover has correction circuits in it to specifically correct the output of the K-63-KN driver. It is hard for me to understand how those correction circuits would be right for any other driver. Not impossible I suppose, but unlikely. Bob Crites

Just goes to prove once again that you should never leave a mold anywhere except a place under your personal control. To the person who had the mold made, it is a 10 to 20 thousand dollar investment. To a place that uses the mold to make your parts, it is just a heavy chunk of metal in the way until the next time someone puts in an order to use it to make some parts again. The first mold I ever had made, I left at the foundry that made my parts. The second time I wanted some parts made from that mold, found out the foundry went bankrupt and my mold was just in a pile of "company assets" that got sold for scrap to pay off creditors. The next mold I had made stays in a wooden box with handles in my warehouse. We call it the Ark of the Covenant. Just yesterday, we got it out and hauled it to Grace Manufacturing to have 1000 horns made. When I pick up those horns, next week, I will have them put the mold back in my "Ark" and it will go immediately back into my warehouse until needed again. I will not leave it with the place that is going to use it (like most people do).

And now the mold that made the plastic cups has been lost!!

I thought I would go ahead and post the test results after changing out the autotransformer. So you can compare them next to each other, I will post one of the crossover with the T3A and one of the crossover after just changing the autotransformer.

I did not listen to them. I can say with certainty that I would not like the midrange recessed that far back behind the bass and treble. I like hearing the midrange at the same level as the other two drivers.

Problem solved. It is the T3A autotransformers, both of them (perhaps all of them). I replaced with a pair of mine and the spike is gone. No use asking me to explain this. I have no idea.

The story I heard was that the prototypes of the K-55Ms had higher output, so the crossover was made compensate for that. Then the actual production models showed up and did not have the higher output. But anyway, I did my own testing and pronounced all to be essentially equal.

That is probably where I will go next. Tomorrow, not tonight.

But it turned out not to be more efficient than the K-55V.

Yes, as long as the change is not by a large amount (like the case I was asking myself about earlier) depending on the type of crossover. This is complicated and one needs to read the thread (that I can't find right now). I hope that is adequately confusing.

Answer: No, that is not it.

Question to myself. Could I be seeing something similar to what I saw on a crossover that Dean built some time ago?

If that were a problem, we would see that as a change in the value of the inductor. We do not see that as we have a perfect tweeter curve.

Dean, look at the blue line. Yes it is attenuated more than the AA as we expected. What we did not expect is that before we see that additional attenuation, it went 5 or so db high at first right at 400hz.

Hopefully the plastic input terminal cup is not broken. If it is not broken, you are not into much of a problem yet. How about sending me an email with some pictures. Bob Crites bobcrites@mac.com

I have seen a number of the older K-55V that were still working but had lost some of the output in the lower frequency range. I had thought the loss would be in the highs, but have never seen that, just lower output below 1000hz. In every case, replacing the diaphragm fixed that right up. Bob Crites

Yeah, I like that better. If they make those caps using the same stuff they used to use, they should not effect the inductor. Bob

How about swapping places with the air core inductor and the zener diodes?

I think the air core inductor may be too close to the steel frame of the autotransformer. I would place it well away from the autotransformer. Bob

The size of the hole in the gasket matches the actual outlet size of the K-55 driver.

Larry and Steve heard Jubs at my place then bought. Bob Crites

Yes, looks like you have to get the 880 to get the Kelvin test leads and DCR.

B&K Precision now makes some meters less expensive than my B&K 885. You should look at the B&K 879B and 880. You can find the 879B for around $250. Bob Crites

Well I think it certainly tells you if a cap is good or bad. To really read the good caps, seems to me it needs another digit of resolution. The Aerovox read like I usually find them. All the 2 uF are pretty bad like I usually find them. I think ESR becomes pretty easy to hear at above 0.5 ohms.