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Crites A/4500 crossover with K77M tweeter?


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Bob has done some listening with this combination and didn't damage the K77.

it's just not recommended. probably with low power it would be fine.

Klipsch uses the 4500 crossover point for K77 in the current Khorn and LaScala, but uses a 6th order crossover, which i understand (actually i don't have a clue) provides better protection for the K77 than the type A @4500hz.

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Well, one crossover is now installed! So far, so good. No tweeter distortion, after brief testing. I have to stick it back in the corner, but sounds smooth. I'm not sure if I have to adjust the autoformer, since the K77M is different than a Crites tweeter obviously. I don't know for sure what tap goes to what wire yet.

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"Klipsch uses the 4500 crossover point for K77 in the current Khorn and LaScala, but uses a 6th order crossover, which ... provides better protection for the K77 than the Type A @4500hz."

Hi Dee -- I'm nitpicking here, but when you change and add parts, fundamentally changing what the network does -- it's not a "Type A" anymore. At any rate, steeper slopes reduce the amount of total energy going to the driver leading up to and near the transition points:

"Low frequencies will damage tweeters. Using a second order (12 dB per octave) or third order (18 dB per octave) high pass filter will reduce the lower frequencies at a steeper rate than a first order filter. A tweeter with a third order high pass filter with a crossover frequency of 5000 Hz driven by the 100 watt amplifier...will recieve about 1.6 watts at 2500 Hz versus 25 watts with a first order filter at full output."

Absolve -- The tweeters on the networks for the big Heritage stuff are unattenuated, they are run full out -- I suppose you could move the tweeter down to tap 4, along with the squawker, but that would be a 3dB drop, which might be too much. I did this once for a short period of time, so I know it works, but to be honest, I don't know the full ramifications of hanging two drivers off of the same tap.

You can also visit www.alkeng.com and consider purchasing a pair of Al's tweeter attenuators. He has two versions: adjustable L-pad type and transformer type (recommended). You can use them without making any other changes to the crossover, which is nice. I recommend that anyone planning on playing around with different tweeters to invest in a good pair of attenuators.

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Thanks for the info! I'm not sure what tap goes where on the 3654 transformers. I was looking for a manual or data sheet, but I didn't see one for these specifically. I'm really enjoying the sound now, much smoother for extending listening periods and better intelligibility. I'll have to email Bob about adjusting the levels, but it's certainly an improvement over the AK2. Those stock caps in the bass bin crossover are huge!

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The 3654 is a beefier version of the original Klipsch T2A. Tap 5 is the input tap. There is 13mfd capacitor sitting between input positive (from the amplifier) and Tap 5. Also attached to Tap 5 is a 4mfd capacitor which connects to Tweeter + on the terminal strip. Tap 5 provides for no attenuation (it's an "input tap"). Now we're left with the output taps. Each remaining tap provides for 3dB of attenuation. So, Tap 4 is -3dB, Tap 3 is -6dB, Tap 2 is -9dB, and Tap 1 is -12dB. There are no other in-between settings unless you go to a different autotransformer (3636 or 3619-ET), or another option with your existing units that would require a redesign. I'm going to assume that you disconnected or removed the parts for the AK-2 low pass section in the bass bin?

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You're going to hate me - but changing the midrange level will change the crossover point. Hey, that's cheating, I thought we were talking about tweeters. Don't mess with the midrange, I'll explain later (no time right this minute).

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