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Save yourself a lot of time and effort

Posted by Lynn Olson (M) on August 25, 2004 at 21:03:20

In Reply to: Claus Byrith's 30w PP posted by beaufortralph on August 22, 2004 at 14:04:49:

And borrow a classic amp from the 1950's and try it on your speakers. Frankly, I think Sansui speakers are pretty much bottom-of-the-barrel, no better than Radio Shack's offerings, but you'll still hear the obvious difference between the solid-state you're used to and the borrowed tube amp.

Keep in mind most 1950's and early 1960's products were quite similar in circuit design, with Williamson/Dynaco variants being the most common by far. These are characterized by Class AB push-pull pentodes with 20dB of feedback, a Williamson-style front end, and the EL34/6550 outputs either driven by a dedicated driver stage (Williamson) or directly off the phase splitter (Dynaco). Some have solid-state rectifiers, some have tube rectifiers, some have circuit boards, some have point-to-point wiring. All of these affect the sound to a degree.

Nevertheless, the basic character of all the vintage amps is pretty similar, since the circuits and selections of tubes are similar. There just aren't that many ways you can build a Williamson or Dynaco amplifier. There are also amps that are a little bit different, like the Quad II, McIntosh, Acrosound, or Citation II, but these are collectible and priced accordingly. They still use 12AX7's, 12AU7's, EL34's, or KT88/6550 tubes, so the "flavor" is recognizably vintage.

The amps you see in this forum are quite different, and aimed at folks aren't into the vintage sound. Interstage transformer coupling is more expensive, and precludes (global) feedback, which is why it was almost unknown "back in the day", when every amp had to have feedback to stay competitive in the spec race.

If you're just getting started, I wouldn't jump into the deep end of the pool first thing. Get acquainted with tube sound - there are thousands of stock and modified Dyna Stereo 70's out there, which are perfectly respectable amps then and now. The traditional favorites of Scott, Fisher, Eico, and many other are all good. Interestingly, the vintage Sansui tube amps were quite good - although the Pioneer and Trio/Kenwood amps were pretty mediocre.

If you're buying, get a unit that's already been restored by somebody that knows what they're doing (suddenly turning on a vintage amp that's been off for the last 20 years will almost certainly blow out the power transformer - old electrolytic power supply caps require a "reforming" procedure first).

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