BEC - you might have them tomorrow

[Jeff Matthews]

FYI on the xovers.

[BEC]

OK

Bob

[DeanG Crossovers]

This should be interesting:

A) Jeff doesn't hear well.

Rick used 'on the outs' NOS motor runs.

C) Horribly out of spec networks sound the same as new ones.

D) All of the above:)

[BEC]

One sniff and I should know the answer.

Bob

[3dzapper]

ROTFL!!!!

Rick

[Jeff Matthews]

I'm betting on A. Ignorance is bliss. You can call me ignorant, but they still sound great to me. []

Bob, tell it like it is. If they're good, they're good. If not, I'm deaf.

[BEC]

Jeff,

Not to worry. I will fully disclose all about your old crossovers. I am all business when it comes to testing. You could be a lawyer, live in a one-star state (Baja Arkansas) and be in the town with my ex-wife (Houston) and still I would fairly test your crossovers.

Man, I love the smell of capacitor oil in the morning.

Bob Crites

[meagain]

Oh wow. Been wondering what inside those things. What am I looking at? What's the deal with the 'ribbon'?

[Jeff Matthews]

Seeing as I would be the only 1 in over a few hundred to have had non-decayed 30-year old xovers according to my hearing, this will be interesting.

[NOSValves]

With that 6000 watt amp at 180dB I bet the original worn out crossovers sound better then anything Bob, Dean or Al could build for you[]

[meagain]

Tension so thick you could cut it with a knife.

tap tap tap....

[BEC]

They are not here yet.

Tick-tock Tick-tock Tick-tock

Suspense getting to me.

Bob

[Jeff Matthews]

Maybe tomorrow. I thout w/Priority Mail, they might make it from Baja Akansas to Arkansas in a day. I'm betting on tomorrow.

[BEC]

They arrived in the mail Saturday.

Bob Crites

[BEC]

Here is what arrived from Jeff. Appear to be a pair of completely original Type AA networks. Notice the shiny screws in the small air core inductor. Should have been brass so as not to effect the value of the inductor. These are steel. A very common mistake by the crossover builders at Klipsch on these crossovers.

Bob Crites

[BEC]

Crossover #1 test results.

Bob Crites

[BEC]

Crossover #2 test results.

Bob Crites

[meagain]

May I ask what the part looks like that you are referring to? The inductor?

[BEC]

The tweeter inductor is the round device in the upper left corner of each crossover in the picture.

Bob Crites

[BEC]

Analysis:

This pair of original type AA crossovers test in the range I expect to see for 30 year old capacitors. A perfect capacitor would measure as a pure capacitance. No capacitor is perfect, though, and we can sum all the losses inside the capacitor and express them as value of equivalent series resistance (ESR). In a good capacitor, this value should be very low, in fact most good Polypropylene capacitors measure in the area of a few hundredths of an ohm ESR. Looking at the circuit shown above, one can sort of sum up the losses all the way from input to the tweeter and find that those losses are almost 2 ohms through the crossover. Replacing those caps with good ones would cut those losses to a value of less than .05 ohms. 1/40th of what they are now.

An interesting point is the value measured for the 13 uF caps. It is unusual for me to find those that far out on capacitance. These are both at around 12 uF, or almost 8 percent off the stated value. The caps are not marked with a tolerance spec, but that seems a bit much to me for those to have changed over the years. Perhaps they were at that value when new.

The discrepancy between the measured value of the tweeter filter inductor is caused by use of the wrong screws to hold them down to the board. This is a common mistake found on these AA crossovers. The screw is steel which becomes a core for the inductor. The screw is supposed to be brass which would not have effected the inductance value. A stainless steel screw could have also been used. That is what I always replace these steel screws with when I rebuild the crossovers.

I would recommend these crossovers be rebuilt.

Bob Crites