SpeakerTalk

willem-57 · Posted: Wed Dec 14, 2016 11:08 am Post subject: Kef crossover RR 105.4

At first i will wish you all a happy Christmas and Newyear! Very Happy

As you know i've refurbished-rebuild a set of the 105.4 and still have questions about it's crossover. As Speakerguru already mentioned in another topic, there are different types designed and Kef has send me a PDF with the first version of the crossover.
Because most 105.4 that are sold have the second version like i have, I've made a schematic of the crossover from the Kef PDF and trying to get it clear.
Capacitator C12, first version valeu is 2.2uF, the later version is 4.2uF. These working for the tweeter. Concerning the resistors, there is a difference between the R3, the first version had 15 ohms, the later version has 22 ohms. It's in the zobel tweeter network.
The inductors i can't measure, so i don't know there value's and if there are differences between the first and later version.
On the Kef files/layout i can't read witch one is L1 or L2, so i have put a ? behind the L1 and L2, witch is really L1 and L2?

Who can help to get the picture right and complete Question

Schematic:

The old Kef files i got, remember these are from the older first version.
They are hard to read, sadly, cannot see witch is L1 or L2...?
You can also read that this is made in july 1980.

speakerguru · Posted: Thu Dec 15, 2016 10:51 am Post subject: Re: Kef crossover RR 105.4

willem-57 · Posted: Thu Dec 15, 2016 12:30 pm Post subject:

Thx for the reaction speakerguru,

What i wanna know certain if the L1 is the left one on the photo, ik think so, but i'm not shure. Because i cannot see it on the Kef drawing i got. Thatswy i have put a ? behind their number.

speakerguru · Posted: Thu Dec 15, 2016 10:42 pm Post subject:

It's a reasonable bet that L1 is larger in both inductance and physical size than L2. Even if the exact values changed with different issues of that model they would still be in the same ballpark. Another clue, very roughly, is that inductance is proportional to the square of the number of turns on a given core. L1/L2= ~3 so L1 will have ~1.7 x the number of turns of L2.

At the risk of stating the obvious, L1 is connected to the amplifier (via the relay and capacitors) L2 is connected to the woofers. You can see what goes where by looking at the trackside of the pcb.

willem-57 · Posted: Fri Dec 16, 2016 8:21 am Post subject:

Thx,
So i gambled right, the bigger one must be L1. Very Happy

To make the picture complete i've made a picture with the up and down side of the crossover together. It,s important to say that this is only the 105.4 sp 1129 version. The RR 105.2 is the sp 1119 and is in many ways different Exclamation