"Charged Coupled" crossovers?

[Hoerninger]

Using LTSpice I took a look at the voltages at a 6 dB/oct highpass with 2 kHz.
I would have liked to add the circuit file. But I am not used to Windows and I do not know how to perform. With Ltspice Getting Started Guide you have a very good entry into LTSpice.

Charging up:
The first plot shows how the voltage across one of the paired capacitors is rising.
After about 300 seconds both have a voltage of 9 volts.
After these 300 seconds there is a burst of 10 cycles at 3.5 kHz. The source has a voltage swing of +/- 18 Vpeak (12,7 Veff; 36 Vpp).

Going on I want to give you two automatically calculated examples which show other results some have discussed before.
____________
Peter

[Hoerninger]

Cut off region (lower than 2 kHz):

A sine wave of 20 Hz and an amplitude of 17.5 Vpeak is applied (12.4 Veff, 35 Vpp).

20 Hz is far within the cut off region and so there is only a small voltage at the speaker, smaller than 0.2 Vpeak - red V(n003).
At C1 rsp. C2 the voltage swings are between 0 V and ca. 17.5 V – green V(N002,N001) and blue V(N002, N003). Each capacitor has about half of the generators voltage swing.

For a further increase of voltage reversed polarity will occure. This may cause distortion. But normaly the overtones will be attenuated with increased frequency and only a minority part will belong to the pass band.
____________
Peter

[Hoerninger]

Pass Band (above 2 kHz):

A sine wave of 20 kHz and an amplitude of 17.5 Vpeak is applied (12.4 Veff, 35 Vpp).

The voltages at each capacitor are relativly small between 7.9 V to 9.5 V – green and blue. Most of the voltage is at the speaker – red V(n003), nearly the whole swing of the generator.

In the pass band the input voltage can be greatly increased until the capacitors are driven into reversed polarity. The source voltage can rise up to 38.8 Vpeak (26.9 Veff; 77.6 Vpp).

There is only little chance that in the pass band distortion by polarity change will occure. It would be fairly loud, but then the ears produce distortion as well.
____________
Peter

[Allanvh5150]

The charge-coupling helps control this issue but it does not control inductance due to the wrapping of the plates much like a coil of foil.

Good point Ian. I am not sure of the inductance of say, a 5uf cap is, but if we put 2 10 uf caps in series for our CC network we will get a larger series inductance. However, if we use 4 x 5uf caps in series/parallel, the series inductance will be the same as the single 5uf cap. Correct me if I am wrong. I am not sure what the reasoning is for not using bypass caps in a CC network but generaly, a small bypass cap of 0.01uf will make the series inductance very small. One could just use 1 bypass cap for the whole group. I don't think the term "bypass" should be used because the cap doesn't bypass anything at all. The impededence of the 0.01uf cap is hugely higher than the actual network capacitor. It does not bypass the high frquencies around the main capacitor as some would suggest. It mearly "cancels" the series inductance. You would use a "bypass" capacitor to route the high frquencies around the L-Pad in a crossover; aka compensation network.

p.s. So why don't we use a 0.01mH in series with the inductors to cancel their parallel capacitance?

Allan.

[Robh3606]

Hello Peter

Thanks for running and posting the Spice plots.

Rob

[Hoerninger]

Rob, thank you.

In post #108 there is a small mistake when I started calculating by hand.
The source voltage may rise to more than 38.8 Vpeak as the new spice plot demonstrates.
The consequence is the same, the ears produce distortion as well - as long as the driver will not get burned.
____________
Peter

[4313B]

Here's an example for the 4355. I can't take credit for the nice box which another forum member built. He wanted his networks external. I think the connectors alone were something like $400 for all sixteen ...

[4313B]

of course, LEAP probably models a theoretical perfect capacitor and doesn't cope with things like dielectric absorption, internal resistive leakage, parasitic inductance, or any of the rest of the little nasties of the real world, eh?

[note I said probably, I've never used LEAP, I'm just guessing]

Here's the editor box in LEAP.

This particular file is Greg's LEAP file from the Everest II which I am modifying for use with older dual 1500AL's instead of the Everest II's newer 1501AL's.

[pierce]

Here's the editor box in LEAP.

This particular file is Greg's LEAP file from the Everest II which I am modifying for use with older dual 1500AL's instead of the Everest II's newer 1501AL's.

I'll bet its fun figuring out those values for real world caps from the typical vendor spec sheet... or do you measure them on the bench?

[midlife]

Here's an example for the 4355. I can't take credit for the nice box which another forum member built. He wanted his networks external. I think the connectors alone were something like $400 for all sixteen ...

That is an immaculate piece of work, thumbs up.

[jblsound]

Here's an example for the 4355. I can't take credit for the nice box which another forum member built. He wanted his networks external. I think the connectors alone were something like $400 for all sixteen ...

Just beautiful
That pic makes me want to re-do the C-C XOs for my L212s, as I've got the three cards stuffed into the tops of the boxes. One mounted to the right, one left and the third across (vertically) the back's opening.

[jblsound]

Having used a C-C pair of L212s for 5 years, in many different ways. freestanding stereo setup, mains in a MC HT, and wall mounted nearfield, the nearfield might be the best at showing off what C-C can do.

As I type this, I'm listening to those speakers all of 4 ft, or less, from my chair. As all the other walls in this room are more than 4 ft from the speakers the nearfield setup eliminates the room from the sound. I hear details of songs I know very well, that I never noticed before, and so smooth, and clean, clear.

And as they are wall mounted and gain 3db @ the low end, no need to use the sub.

[Hoerninger]

I'll bet its fun figuring out those values for real world caps from the typical vendor spec sheet...

Looking at LTSpice there is a window for capacitor properties as well. The database of stock capacitors does unfortunately not show those capacitors we would like to have in a deviding network.

There seems to be no known possibility to simulate dielectric absorbtion (capacitor soakage) which is CC applied for. The usual modelling with paralleled R-C combinations will only show linear dissortion but not the nonlinear ones.
[The effect of CC could be shown in a simulation ]
Any idea?
____________
Peter

[John]

Here's an example for the 4355. I can't take credit for the nice box which another forum member built. He wanted his networks external. I think the connectors alone were something like $400 for all sixteen ...

That picture is a repeat.

Would be nice to see some other angles of that nifty cabinet.

[midlife]

Does charge coupling yield as good of results on horn loaded systems as it has on more conventional speakers?