I hope this pic comes through. It's 128K worth of my original sketch.
Guess I should point out that you must leave the high-pass section in if you want to retain the 500 ohm impedance as presented to the source (Quickie). You don't have to use it - go ahead and take the output to the fullrange in parallel with the input. But the highpass section acts like a Zobel to keep the impedance of the whole crossover constant.
As shown, the lowpass 500 ohm load will pull the Quickie output down about 3-4dB in the bass, but unload it above the crossover for full output. So there will be a modest shelving filter going to the fullrange.
Thanks Paul!
It's still sitting on my bench at home, so I can put the high pass section back in.
The shelving effect is the reason for the Quickie. I get to boost the low end back up using the Quickie, which goes to Paraglow II's, and send the full range to the Excite II's, which go to the lowther front horns. As a bonus I get to adjust the low end for different listening volumes. Speaker leads from the Paraglow II's to the pi cornerhorns get swapped, since the Quickie inverts (since it's only one triode stage). I hope I'm getting this right.
I guess then an adjustable low pass using an autoformer would be pretty complex.
Thanks again for trying to keep me out of trouble.
EDIT: Oh! I missed that you said there is a shelving that goes to the LOWTHERS! That actually should help pull a little load of the paper cones and add some clarity. I was assuming you meant that the low passed signal was cut by about 3.5db, which was the reason for the Quickie. Still, it all works.
Do you have room here for a short explanation of why the full range output gets a drop below the LP frequency?
« Last Edit: October 20, 2009, 03:28:59 AM by Len »
Paramours
Paraglows
Excites
Heavily modded Soul Sister and Groove Thang
Quickie modded to active low pass filter
Quickie modded to headphone amp
Lots of Bottlehead parts used for building other stuff