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Re: I think we could agree to say...

Posted by Rich Brkich (D) on October 19, 2004 at 20:30:24

In Reply to: Re: I think we could agree to say... posted by ABhagan on October 19, 2004 at 17:53:49:

"Rich, let me get this right, a amp can have a capacitive filtered coupled output and still be called a OTL but a amp that is not capacitive or transformer coupled and operates a Impedance converter, out of the signal path at 250kH is not a OTL?

A cap on the output of an simple amplifer is used to block DC from getting to the speaker... it provides no other function. From an audio signal point of view... the speaker sees the output impedance of the active device (tube or transistor) and the amplifing device see the impedance of the speaker. The capacitor in this case is not an impedance matching or "transforming" device. Inductors are often used on the output of power amplifers (tube and solid state) in such a manner to block high frequency (ultrasonic) info from boucing around through amp (generally through the feedback loop) and driving the amp into oscilation. Again, another reactive device (i.e a inductor or capacitor) that does not effect how the speaker or the amplifing device see each other.

Again, a output transformer at its core purpose in a audio amplifier is a impedance matching device (in the case of tube amplifer - take high voltage low current tube power and transform it to low voltage high current power that is best suited to drive the low impedance speaker load). Look at the Hansen article you pointed me to ... figure 10. As you can see there is something there between the amplifing device and the load.... it is even defined as a impedance matching apparatus in David' patent. The only direct path between the ouput device here and the speaker is a common ground. If there was nothing but a peice of wire a one or two passive parts between the tube and the load, why would there be something worth patenting here????

I'm getting tired and rambling... Alan it is hard for me get into this becuase I get so easily fustrated. Our audio world is not perfect... and full a various terms and terminologies which have certain implied meanings and ond connatations... single ended, push-pull, SE, SET, OTL, etc. If an OTL tube amp is a Orange, and a conventional hunk of iron output tranformer coupled tube amp is an Grapefruit, then the Berning amp is Tangerine. While it may be a relative of both fruits, it should certainly not be confused as one of the other fruits.

OK... now that I've really gone off the deep... Icall it quits for today.

G'nigh all.
Happy Listening,
Rich Brkich
Retailer & Audio Asylum Industry Liaison

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