Alk crossover or other problem

[johns02]

I have the ALK's and the 10 ohm resistor gets very

hot when playing load. Then the horns start to distort like a bad connection. I know I dont have a bad connection because of connection type. Could the autoformer have a bad connection? Then again has anyone had that much power on their KHorns?

Amp is a Mark Levinson No. 23

[Al Klappenberger]

Johns,

The 10 Ohm resistor will get hot if you run it extremely loud, but I do mean LOUD!!! Do you have any idea of how much average power you are putting into them?

AL K.

[johns02]

Al,

Mark Levinson No. 23 200wpc.

It benchs at 288wpc both channels driven.

It will not clip easily though on musical peaks.

I was playing at concert levels.

It did get hot! Will resistors temporarily change value?

[JohnA]

If your horns distorted like a bad connection, I'll bet they were bottoming out in their magnet structure. A popping or crackling sound will result. I'd back off the gain about 10 dB.

John

[Al Klappenberger]

Johns,

I am not sure what to say here. A resistor will get hot if you put enough power into it. That is what a resistor does. It turns electrical power into heat.

Is the network one that I built or did you build it?

A resistor has a temperature change with heat, but only a small one. "Concert levels" doesn't tell me how much average power you are putting into the speaker, neither does amp power ratings. To heat up the 10W reisitor request far more than 10 W into the speaker, and it must be above 400 Hz to heat the resistor! All I can say is that you have something wrong with your wiring or you are runnng at levels beyond anything I could believe. Why did the fuse not blow?

AL K.

NOTE: I looked in my records and beleive this is NOT one of the networks I built. If I am wrong, give me the serial number.

This message has been edited by Al Klappenberger on 07-21-2001 at 06:45 AM

[Al Klappenberger]

I did some computer analysis on the continuous power capability of my "A"

series network with respect to the 10W. 10 Ohm squawker swamping resistor.

The resistor I use is rated at 10W. This means that it will convert 10W of

power into heat on a continuous basis. That is, it can handle 10 Volts DC or

RMS AC across it, continuously, without burning up. It will become hot when

doing so and will probably be to hot to touch. It is also rated to stand 70W

for 5 minutes without bursting into flame.

The input levels necessary to generate 10W of power into the resistor

depends on the frequency. At 500 Hz it will require 25.5W input and deliver

3.2 W into the K55 squawker driver. Since this frequency is near the

crossover, most of the rest of the power is going into the woofer. Since

most of the power content of music is below this frequency, this should be

the worst case in practice.

At 2000 Hz, where the total power is usually far less, 14.0 W input will

deliver 10W to the resistor and 3.2W to the driver. The difference (.8W) is

component losses in the network itself.

I might point out here that this is CONTINUOUS RMS SIGN WAVE POWER! This is

not "peak" power, "average" power or "music" power. 3.2W into a K55 driver

represents continuous sound levels in the area of 110 dB SPL or so, maybe

more!

It is my conclusion that to heat the 10 Ohm resistor to a degree that will

burn you fingers, even at "concert levels", the resistor has to wired

directly across the amp rather than across the autotransformer as it should

be!

This brings up a point that should go without saying. I am happy to have

anyone who is qualified build my network designs for his own use, but it is

his responsibility to see that it is wired correctly!

Al K.

[Al Klappenberger]

Johns,

Several other thoughts on why the 10W resistor may be overheating:

Your K55 driver is bad requiring a high input from the amp to compensate. Measure the DC resistance of the driver, it should be about 10.5 Ohms (DC).

The connections to the UTC 3619 autoformer may be wrong. The terminals are not in a logical order and some units have the numbers shifted which can casue confusion as to which is which. Check the wiring to each terminal carefully.

Al K.

[Elso Kwak]

Hi Johns02,

Maybe your poweramp and/or your preamp is oscillating at a high unaudible frequency. This will heat up the resistor and burn out your tweeters. Also the power amp will be miracously warm without playing music.

Check for oscillations with a scope.

The resistor normaly will only be warm at eardeafening 130 dB, discotheke level.

Hope this helps,

------------------

ELSO

[johns02]

The crossover is wired correctly.

Resistor is after the caps and choke as shown om terminal #5. I built it to the exact standards as specified in drawings by Al K.

It may be the ear deafening levels @ +124db causing the heat! The amp is not oscillating.

I do not have a fuse in my crossover. I have never blown a speaker based on the my theory that power does not always kill, DC does.

[Al Klappenberger]

Johns,

Yes, 124 dB will definitely heat up the resistor! I suggest you unsolder it and check that it is still 10 Ohms. If it has changed value from the heat replace it with a 20W or put two 20 Ohms 10W in parallel. If it is still 10 Ohms, just forget it and keep right on using it. One other thing: 124dB! How on Earth do you stand it!

AL K.

[johns02]

I checked the resistor and it is fine. This is a intermitant problem and only shows up when playing loud. I guess it needs to break down completly to pinpoint. I like to compensate the neighbors noise from the the new pool they just built 3' from my property line! I usually stand in the other room with remote when checking full output. Not good for the ears at 124+ db!!!!