John Curl's Blowtorch preamplifier part II

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I have always been told this Joshua, but never realy experimented with them. I just use motor run oil filled ASC capacitors as a rule with a film bypass cap. As i said, never really experimented with anything else as this seemed to be a good combination, but I would think that a single large film capacitor would be the cats meow.

Oil filled is a good choice for the first filter capacitor after the rectifier, the soakage in such a device can be used to advantage. A secondary advantage is that it is more tolerant of spike voltages than other types and this will lead to a longer operating life. It also is reasonably immune to vibration. EMI/RF filtering should be used at this stage or before it.

For a neutral amplifier I would use a good film capacitor for the final output filter. This acts as both a short term power source and is in series with the output transformer. Sizing of the second capacitor will depend on operating conditions, including voltage, variable load (loudspeaker) and complex fixed loads.

Others would use an oil filled capacitor for the secondary to warm up the sound.
 
DVD and SACD for me, please. CD sucks!

I second that. And LP rules.

Sometimes MP3 can make a bad record sound pleasant though. Actually, I'm mean the sony minidisc since I don't have an MP3 player. Maybe the MP3 compression does the same, but often I'll burn a CD to Minidisc and it sounds really nice through headphones, even though the recording is substandard on our high end rig.
 
This morning, I got my first private message here on how to fix a BLOWTORCH CLONE.
Now, everyone, you will now come to understand why I don't publish schematics, as then, I would be responsible for their accuracy and need to help people in trouble following them.
This does lead to a more interesting topic than some here recently, also very applicable to the BLOWTORCH itself and many other projects. That is the servos used in the BLOWTORCH, what they do, and why I prefer to use them.
I might say in advance, that most circuits do not absolutely need servos. The same function can be done with precision offset adjustment, absolute matching, and coupling caps. It is just that servos, remove any coupling or feedback caps, such were used in the Levinson JC-2, or the JC-3 power amp, for example.
It should also be noted that there are two types of servo used, one is called a 'differential' servo, and once is called a 'common mode' servo. They look superficially similar to the untrained eye, but they do different things to get the output DC nulled. Sometimes, as with the BLOWTORCH, both servos are necessary for optimum DC nulling. I will give more detail, later.
 
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