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In the Forum: Audio Discussions
In the Thread: All Active! A DSET and multi-way acoustic system.

Post Subject: TransientsPosted by N-set on: 4/30/2011

I've been trying to theoretically understand this LF - MF,HF interaction for years without much success.
One thing I've found (putting aside the interaction via PS, the LF OPT core saturation, etc) is that frequencies
close to -3dB points get dynamically attenuated for some small period of time.

This is a pure transient effect, not visible via normal Fourier analysis. The idea is that any reactive element
stores energy and hence needs to charge. This charge comes from the signal. The time scale of the charging
is given by the time constant of the coupling=-3dB point. The closer the signal freq. to the -3dB point of the coupling,
the stronger the attenuation. So when a strong LF+MF, HF signal suddenly appears the LF part, being much
closer to the -3dB point gets attenuated for a some small period of time, while MF,HF not.
This applies to RC coupling, output transformers (Lpri needs to charge), LC coupling, DC coupling with inductive load.
I wrote a small note were this effect is calculated. If someone's interested I can send it.
The moral was that if one wants to loose at most 3% of the signal energy, the -3dB point should be
4x lower than the lowest freq. reproduced.

I have no idea if all that has any detectable effect. I'd also blame the PS intercation and, more importantly,
OPT core, which for strong LF signal becomes less linear than for a weak MF,HF signal. Or all together.

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