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Re: Hoping for a History Leason #2: Dukane 1A475C

Posted by Steve O (A) on March 11, 2007 at 05:36:08

In Reply to: Hoping for a History Leason #2: Dukane 1A475C posted by m8o on March 10, 2007 at 23:16:37:

My opinion is that you're headed down a disappointing road if you're looking to use this specific amp for high quality music reproduction. This is a value engineered PA amp and thus carries some baggage. It was designed to drive constant voltage distribution systems and not speakers directly. The 25 volt winding can be used for 8 ohm loads but it's not optimal. Look at the size of the OPT. it's considerably smaller than the filter choke. Not a recipe for good LF response at full power. Consider too that the OPT contains two sets of independent secondary windings but if driving speaker loads directly, you'll be using only the 25V windings. A lot of winding space is taken up by windings you'll not be able to use. Lots of leakage inductance and compromised HF performance. Bottom line, as a PA amp, not much consideration was give to extended freq response, esp at the low end.

My personal experience with this amp and its baby brother, the 1A435 is that there's something up with the output stage. In just about every one of these, the output tubes have been destroyed by overheating. I don't think the amp is a model of stability. The upside is that the output tubes are 6CD6GAs, a not-in-demand TV sweep tube so retubing is cheap.

Bottom line for me is that these Dukane amps aren't worth the effort but as you'll note from the linked thread, I hoping someone will convince me otherwise.

Also be aware that while an entertaining writer, Joe Rosen wasn't always correct. YMMV

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