2. amps-preamps
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Why tube rectification?

This question is directed at the distinguished members of the forum who design and build tube amps or those who have knowledge of tube amp design. All the tube amps I own/have built us two diodes for rectification. Diodes are cheap, compact and last the life of the amplifier in most cases. Examples include the Dynaco ST-35, the Decware Zenkit1 (which is basically a Decware SE84) and the Elekit TU-8900. All reasonably well respected amps. Yet many of the more expensive amps go with tube rectification, which obviously involves the downside of another tube, more power, more space.

These two competing solutions both supply the basic power to the audio tubes and output transformers, so only indirectly interact with the sound signal. I have not read anything that explains what tube rectification brings to the party. But it must have some upside to offset it's obvious downsides. If I changed over one of the above amps to tube from diode rectification what would I be likely to  hear?

bruce19

Showing 3 responses by larryi

larryi
4,290 posts
 

Well, I wonder if you would like the "unconventional rectifier" in the power supply of my phono stage.  It runs twin 300B tubes as rectifiers.

larryi
4,290 posts
 

I don’t think there is anything close to a perfect correlation between electrical performance and preferred sound.  That is why tube gear is preferred by many, myself included, even if measured performance is not better.  The same probably applies to rectifiers vs. diode bridge.  A local dealer who also makes tube gear uses both.  He recently found an electrical engineer who designs, builds, and repairs gear as a sideline.  Although he is new to the shop, he makes bold decisions.  He took home to repair one of the shop’s custom build.  After fixing it, he said he was thrilled with the sound but thought that an amp this good deserves a tube rectifier and converted it without bothering to get permission.

larryi
4,290 posts
 

Thanks Invalid, everyone else I mention this to just thinks it is crazy.  After 24 or so years of running tube gear, the first tube "failure" I've had is those pair of 300B rectifiers; a shelf collapsed on to the power supply unit which has the tubes out in the open and both tubes got crushed.

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