High pass quality to mains uisng Velodyne DD subs

I have asked the same question a couple of times without getting any answer, but I intend to purchase a SMS-1 and will certainly try the high pass. A better way to minimize the tradeoff between transparency and distortion may be to use a separate high-pass filter like ACI's for the satellites, or to solder a high quality capacitor in series with the main amp. There is a formula to derive the required value according to hinge point and amplifier impedance.

Vladimir...The capacitor idea is attractive, but...

1. The capacitor will give you only a 6 dB filter. It will significantly impact frequencies well above where you want to make the crossover.

2. The capacitors used in a line level filter will be of much smaller value than those of a speaker level filter and can be of the highest quality for less money.

3. The 6 dB filter will cause a 90 degree phase shift. An active line level crossover with the ubiquitous four pole L/R 24dB characteristic has a 360 degree phase shift, which is back to 0 degrees.

4. Active amplification in the line level filter is just several unity gain impedance buffering stages. These are easily implemented with almost unmeasurable distortion.

5. With a capacitor you will not be able to easily experiment with different filter frequencies. You will probably want to do this. Personally, based on much experience in this matter, I go so far as to vary the X/O frequency according to the particular music I am playing, and this requires a crossover with a frequency selection knob.

I have done the capacitor thing in the past, and I think that item 1, above, is the killer. Try it by all means, but experiment with inexpensive capacitors until you decide what you want.

Vladimir, you should take note that using the SMS will overide the servo control in Velodyne's subs and I would guess in others as well. That's the only reason I don't use one with my DD15. If your sub doesn't have servo control then it will not matter.

Rwwear,

I'm not following your last comment. The DD15 comes with the SMS built in. Are you not using the built-in low pass and equalization?

Yes it does and I am but I would like to have one just for the fact I could see the readout without a TV. And it will control other subs.