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Replacement Tweeter for the K-77 Done!!


BEC

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Dee,

Give me some details on what was done to the network you mentioned. I want to do a computer simulation. I would suspect that the improvement is due to the change in the crossover frequency itself and that a network designed from the ground up for this application would perform even better. This is the first I had heard of a network modified for a lower crossover, so I don't know which network was modified or who did it. Hacking on an existing network (no matter what network) is usually a jury rig! I know what is involved in moving a crossover frequency and it is NOT a simple thing to do. Even adding the 4500 Hz lowpass to a stock network like I suggest in an earlier post isn't the entire answer. In fact, it's only half the job. The tweeter filter has to also be totally replaced to move it from 6000Hz down to 4500 Hz. Even then the two filters should not only work together, they should be CONNECTED together. This means a complete rearangement of the wiring. If you don't, computer optimization is required to do it properly. How many people have that software? I have it, but how may other people do you know of has it? SPICE is an example of software that could be used to do it.

Bob has given us an oppertunity to make a major improvement here with this upgraded tweeter. Lets take proper advantage of it by developing a good network to support it. Stop the jury rigging and do it right to begin with! I will glady do the design and post it for the DIY croud!

Al K.

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I'm glad I already have a paid order in for a pair. Can't wait to listen to them!

Bob, is the z-mount an option? Or will I have to (somehow) remove the grill cloth to mount the new tweeter?

Will it sound bad (or at least far from its potential) when mounted on the back (like the K-77 is now)?

Thanks!

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Just to say this one more time (at least), you do not need to modify a current network using a K-77 to see an improvement in sound when you replace the K-77 with a CT125.

Now, having said that, since the new tweeter can take the lower frequencies, I have done most of my listening to evaluate this tweeter with a simple first order network consisting of a single 4 uF cap for the tweeter filter. That allows the tweeter to be crossed at around 4500 hz. Others have chosen to also gently roll off the squawker at about 4500 hz by using a single added 500 uH inductor in series with the squawker output.

The above described mod to a Klipsch Type A network is what Daddydee is using with the new tweeter. I have heard his Khorns set up this way and feel it is the best I have heard Khorns sound.

Now that I can really start shipping these tweeters, we can do a real shake out on finding the right network or networks to get the last bit of benefit from capabilities of the new tweeter.

Here is one fact though. If we are using complex tweeter filters now as tweeter protection, they are not needed with the new tweeter. There may well be other sound related reasons to use a steeper slope but in the change from the first order type A filter by Klipsch to the higher order AA network, Klipsch stated that the reason was to protect the tweeter.

Bob Crites

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Peter,

As far as I know all who have reviewed and are currently using the new tweeters are listening to them mounted behind the motor board as was the way all K-77s were mounted until recent years. That is also the way I am listening to the new tweeters. So, mounted like that, it was the everyone's opinion that the new tweeter is a good upgrade to the K-77.

I really don't know if there is much difference between mounting in front of the motor board or behind. My feeling is that if anything is effected by front mounting it would be a slight effect on dispersion.

Bob Crites

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Guys,

Now that I know what the network mods are, I'll do some computer work and start a new thread about it later today. I have already done a preliminary design using 2nd and 3rd order filters as a mod for the AA and I don't like it. It's only a short step more to the "right" thing.

What Bob said above is worth repeating: The new tweeter will drop directly into any speaker that uses the K77 tweeter. No network mods are necessary. What I propose is simply a way to take more advantage of the upgrade.

Al K.

BTW: Dean and I have put our heads together about the "Super AA" network and there are some changes in thinking about it to come. It will NOT factor into the new 4500 Hz tweeter network design though.

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Bob,

I'll be ordering my third CT125 for my center channel in a week or two.

Al/Dean,

Do you see any real benefit to mod the crossover down to 4.5 KHZ when using a horn such as the Altec 511B. I am using Bob's prototype tweeters with Al's Universal replacements and a K55 mounted to a 511B and it seems to be pretty seamless.

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I will certainly be busy shipping tomorrow. So far my list shows about 70 of the tweeters will be purchased. About 30 are paid for and will be shipping as soon as I can get them shipped.

Anyway, I only have about 60 horns in this first batch, so they won't last very long. I hope I can have another batch of horns in the next few days.

Bob

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