Question for the crossover guys here...

[moray james]

I have been looking at the crossovers for the KLF 20 and 30. These speakers are three ways with dual woofers. The KLF 20 has dual ten inch woofers and the KLF 30 has dual twelve inch woofers. Both designs use the same mid and hi frequency horns. The major difference between the two crossovers in these speakers is in the mid section of the network with the KLF20 using a T7A auto transformer and the KLF 30 using a T5A auto transformer. The KLF 30 incorporates a 22 ohm resistor feeding the T5A and also has a 1.75 mH inductor across the input of the horn. I am wondering why the difference in complexity and partsof these two crossovers? I can see the need for the mid horn of the KLF30 to have to run a little hotter to keep up with the twin twelve inch woofers. Both speakers uses essentially identical tweeter crossover section components with the KLF 30 not using a 40 ohm swamping resistor on its tweeter for some reason. I am wondering if the simpler KLF 20 network could be used with two twelve inch woofers as long as the inductor and cap of the woofer section were adjusted and the mid section was adjusted to level match? Thanks for any assistance or explaination. Best regards Moray James.

Both network schematics can be found in this thread.

http://forums.klipsch.com/forums/t/130178.aspx

[Trey Cannon]

As there were 3-4 versions of the KLF networks...you need to understand which you you are looking at. I think the 30 is version 4, Not sure on the 20.

Sure the KLF 20 could be use with a pr of 12's, but it would have to change to match level and crossover point and at that point it wouldn't be the KLF 20 network any longer.

The answer to the klf 30 not having the resistor is that the mid is let through a bit more in the 30 so the TW needs to keep up. the mid has a bit different slope on the tweeter side of the curve.

In the 20 the mid is blocked a bit more to match the 10" woofers thus the TW is level match.

Parts are not used to add cost to the product, they are used to reach a goal. IF you have a different goal than the original speaker, then yes, changing parts will be needed.

The small differences you see in the network makes a large difference in the outcome of the acoustic response.

Warning: the drivers for the KLF line are NLA. we may have some of the HF drivers, but they will be $400 or so.

[moray james]

Trey: thanks for your reply. I have just tried to post coppies of these two schematics but this system will not let me post in the format I have them stored in and I don't know how to change it. I have the two schematics drawn out on paper here so I can see what is what easily but others who are interested will nave to copy them from the link provided.

So we can be on the same page I will go through the value. Both woofer sections (klf 20 & 30) are identical except for inductot value and cap value, the klf 20 has a series 1.6 mH inductor and then a parallel 80 uF cap, the klf 30 has a series 1.35 mH inductot and a 97 uF cap. So those sections are adjusted for the difference in voice coil inductande and the difference in crossover frequency. The tweeter sections are also very similar with a series cap (2uF) a parallel inductor (0.16 mH) and a series cap (2 uF) the only other differences between the two is that the klf 30 does not include a 40 ohm swamping resistor where the klf 20 does. The swamping resistor seems to be present in a number of tweeter section of Klipsch networks.

The mid range section is where the main differences lie between the two schematics. The klf 30 has a 6 uF cap in series with a 22 ohm resistor feeding a T5A auto transformer, tap 3 is used for the pos lead to the mid horn and there is a cored 1.75 mH inductor across the voice coil of the horn. The kls 20 uses a 1.25 uF cap in series with T7A tap 2 is used for the pos lead to the mid horn.

So for this discussion we will not worry about the swamping resistor on the tweeter section (unless you feel it should be discussed) and consider both the woofer and tweeter sections essentially the same. That leaves us with the two mid range sections which are different. The stated crossover point for the klf 20 are HF- 7K and LF-750 Hz. The klf 30 is HF- 7K and LF- 825 Hz. I see that the klf 20 shows the T7A as being -10 db for the mid horn on tap # 2 since the mid horn has an efficiency of 105 db that means the mid horn is running at 95 db, is that correct? The schematic for the klf 30 shows the T5A with the mid horn on tap # 3 as 6db is this minus 6 db? That would have the mid horn running at 99db which would seem about right. The auto tramsformers are where I get confused as it is fairly complicated to calculate the reflected values and such. I will stop here and let you respond to see if I am on track so far. Thanks Trey. Best regards Moray James.