Empirical is Good ! ( Redux )
Mark,
About your HF bypass circuit ;
If you are convinced that you haven't miswired something and if you are convinced that the MF variable Lpad offers enough attenuation to the whole horn circuit , then ;
- Start reducing the value of C ( in the HF bypass circuit ) . And for now get rid of any drive pot and get rid of the resonating coil . ( You can attempt to add them back later in the process ) .
(i) If the HF bypass circuit ( when the MF is properly balanced to the le14 ) has bled into the final FR ) too much 5 to 10 K information or lower / then simply reduce the value of the cap by a similar amount ( in octave terms ).
- ( 5 to 10K represents one octave of information ).
- Halving the size of a cap shifts its F3 up by one octave.
- By extension , shifting the F3 up one octave will reduce all content below the F3 by a comparable amount. ie ; what was at say minus 6db will now be at minus 12 db ).
(ii)
- If the HF bypass circuit is "contaminating" 10K by adding an addition 6 db of unwanted information / then shifting the F3 point of the bypass cap upwards 1 octave will, reduce this contamination by 6 db.
- As I said earlier, everything we are hearing/seeing ( the net contribution for this HF "bypass" circuit ) comes from below the caps F3 point / therefore shifting the F3 point ( of that cap ) determines how much level ( of any one frequency ) is added into the final FR plot ( until the original MF signal swamps out the HF contribution ) .
- So everything "contributed" ( from this "bypass" circuit ) is electrically filtered at an attenuation rate of 6 db per octave .
- So try a .5 uF ( bypass cap, if you are presently using 1 uF ), then remeasure and post your results .
:)
ps ;
Quote:
Originally Posted by Zilch
Can't be right. C6 is already 1.0 uF.
Earl's gonna have to resolve this one.
Me, I'd be trying lower value C6's....
- Yeh, what he said !
- I've lost track, is C6 the same cap I'm referring to in the bypass circuit ?
( I don't keep this schematic taped to my computers' monitor :p )