DeadEars
100+ Head-Fier
- Joined
- Aug 13, 2009
- Posts
- 335
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- 36
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Quote:
Power transfer at different frequencies is a real problem. How do we know which amps will perform across the frequency spectrum? It's a crap shoot.
The power supply issue is what draws me to the Luxman. The company started out building transformers (a big part of the power supply pie) and the company's amplifiers had (have) plenty of grunt.
As far as putting transformers in the audio signal path (which I think you are talking about), I thought that was a bit of no-no these days. For example, a transformer used in the signal path to amplify the output of a moving coil cartridge to get it to the level accepted by a moving magnet phono input will lead to veiling, limiting of dynamics and other colourations. I would think that the use of a transformer in the signal path of a headphone amp should also be avoided for the same reasons.
That's the problem with the common wisdom. It is so often generally right, but can be specifically wrong.
There are transformers and then there are TRANSFORMERS. As an example of the latter, I have a pair of Harmon-Kardon Citation-II amplifiers from 1962 that have humongous output transformers. I've put them on my electronics bench with a signal generator and an old Tektronix scope; their square wave output at frequencies from 8cps to almost 80,000 Hz, at full rated power is extremely good.
As an example of the former, unfortunately, the Hammond transformers on my MAD amp don't fare so well. Not bad, but not in the same class. Replacing the 'lytic output caps with Obbligato oil caps has really made it a much nicer sounding amp, but here the transformers are the limiting factor (nice topology tho)
Another good set of transformers I have hope for: I've been building yet another Dynaco ST-70 kit using Kevin Carter's kit with all-transformer coupled stages (see http://www.kandkaudio.com/poweramplifier.html). Only 15wpc, but very, very good power transfer across the audio spectrum (at least for the input board, which is all I've built so far). Might make a very nice headphone amp.
Fun stuff!