General passive-line level filtering issues. (BD-Design)

by Bert , Tuesday, February 12, 2008, 10:48 (5910 days ago) @ Cappy

Hi Cappy,

It works very well unless there is too much low frequency noise in the
system, since any noise will be amplified by the main amp and bass amps.

True but there is one problem with amplifiers who care about impedance changes (like most tube amps) when connected to an unfiltered Oris system (Lowther, AER, Fostex, etc.) which do have a relative big impedance hump in the lower frequencies. Where that hump is depends on the way the back of the chamber is closed, partly closed or not.

At the "hump" frequency the main amplifier (sensitive to impedance changes) will give a higher output picked up by the line level filter which is the main cause for a less controlled bass. When the Oris horn is filtered then the amplitude changes gradually and gives hardly a problem to tune it all in (but also the reason why passive line-level filters have to be tuned at home).

Bert

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BD-Design - Only the Best!

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