Re: OPT equalising circuit

"Patrick Turner" <info@[EMAIL PROTECTED]
> wrote in message
news:481EE349.B7DCE585@[EMAIL PROTECTED]
>
>
> Iain Churches wrote:
>>
>> "Phil Allison" <philallison@[EMAIL PROTECTED]
> wrote in message
>> news:681onaF2qvh31U1@[EMAIL PROTECTED]
>> >
>> Patrick T wrote:
>>
>> >> I don't know how many tube amps you have designed and or built or
>> >> repaired count. Many tube amps will oscillate at HF when connected
>> >> to a capacitor load.
>> >
>> >
>> > ** Only a psychotic lunatic would deliberately connect a capacitor
>> > across
>> > the output of a tube audio amp.
>>
>> Quite wrong Phil. 0.22µF is a standard (albeit tough) test
>> for tube amp stability.  You will find it mentioned in articles
>> by Tremaine and Crowhurst.
>>
>> >> In order to gain unconditional stability ....
>> >
>> >
>> > ** An unnecessary,  pedantic,  pseudo technical wank.
>>
>> Unconditional stability is more im****tant now that is was
>> in the hey-day of tube amps when many speakers were 15
>> Ohms, and formed benevolent loads.
>
> It matters not what the speaker ohms are.
>
> 15 ohms ain't necessarily easier to drive or
> inclusive of less reactances than any other Z

My point was that most if not all conformed to
IEC/EN/BS EN 60268-5. (The ESL was the
exception - Russ Walker used to joke that Peter
his father was granted a dispensation by the Pope:-)

Specifications are sometimes less rigourous these days.

I have been at demos where amps that perform
perfectly well into Tannoy, Kef and B+W are
trembling on the threshold of instability when
presented with some other loudspeaker as a load.

Iain