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In the Forum: Audio Discussions
In the Thread: Passive transformer based preamp
Post Subject: Re: Kill me, kill me, kill me!!!!Posted by Romy the Cat on: 11/4/2005

 morricab wrote:
I do have a speaker with a flat impedance.  It is an Apogee Caliper Signature with an impedance variation from 3 to about 4.5 ohms over the whole range.  Fortuneately it is not so dead as your example as it has about 86db sensitivity.  However, it is like an electrostat in that inspite of having a low voltage sensitivity it does not sound "dead" like a conventional box speaker of the same rated sensitivity.  This could be due to the moving mass of the drive elements or because thermal compression of the planar drivers is not a concern like it is for a normal low sensitivity cone.   I also have full range electrosats so here again is a design good for OTL.  High sensitivity horns (with moderately high impedances) should work very well indeed and I don't see again why they shouldn't be OTL friendly.  You have a similar problem with matching loads with a SET amp of moderate output impedance.  You will certainly get frequency response variations unless the same conditions are met.

Oh, morricab, way did you said that you are in the Ribbon would. They are tonally different speakers and any aspect of common sense are not applicable for then them. With the ribbons and electrosats you do need an amplifier but you need a super high voltage-pusher-machine that will be able to drive high capacitances, low mutuality and high believe that concept is more important then a result… :-)

Really, with electrosats- ribbons you do not need an OTL but you need a super OTL, or some kind of direct-couple 400W-500W monsters with 5-6kV on its plate. Really those amps could not be recognized as OTL class but rather as a self-contained direct coupled aberration uses a remedy for some very faulty loudspeakers.

Ok, now you do hate me…
:-)

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