Rectification

chadh · « **on:** 14 Mar 2006, 11:05 pm »

Rectification. It sounds painful. But what is it?

I'm currenly agonising over my first tubed pre-amp purchase, and have discovered that some of these things are "tube-rectified" and others aren't. I'm not sure whether that means that the others aren't rectified at all, or whether they are transistor rectified.

More importantly than the "what is it" question, of course, is the "what difference does it make" question. Is it clear that one would prefer tube rectification? And does it usually make a big difference?

Thanks.

Chad

JoshK · « **Reply #1 on:** 15 Mar 2006, 12:33 am »

rectification is the process of turning AC power into DC power (i.e. sine waves into flat lines). tube rectification is said to be preferrable by some, while others disagree. The pro's of TR say that it avoids the noise induced by SS switching in diodes, but modern soft recovery bridges seem to make this mostly moot, afaik. others just think TR sounds better....don't know, but I use it in my tube line stages.

TR has one nice benifit....slow start up which keeps the tubes from getting hit hard with B+ voltage before they are warmed from the heater voltage.

MarkM · « **Reply #2 on:** 15 Mar 2006, 01:22 am »

For ss rectification, look for an amp with a delay on the B+ power as well. The better designs incorporate a relay. It will add life to the tubes down the road. I built a tube amp with a relay on the B+.

As Josh noted, the FRED type diodes will have a noticeable sonic difference. Hard to believe diodes can have an impact, but they do. Just a few things to consider. Tube amps are easy to tweak, simple as changing tubes or get out the soldering iron...

tanchiro58 · « **Reply #3 on:** 15 Mar 2006, 01:32 am »

In addition to Josh's explanation, TR has more beneficial to whom prefers to listen to tube. You can roll the best tube rectifier like the U52s or 5U4s or 274s(mostly for power amps) or the 5Y3(U50) for the preamps or DAC. In the tube system, TRs give you more musical, more juice and more articulate warm sound(if you match well between components) and also more lush sound.

eico1 · « **Reply #4 on:** 15 Mar 2006, 03:25 am »

If you have a tube rectifier socket, you can always buy or build a ss replacement to plug in. The ss wil be lower impedence, hence more power avaialble for a power amp. A pre-amp shouldn't care as much for the lower impedence.

steve

dado5 · « **Reply #5 on:** 15 Mar 2006, 06:56 pm »

Quote

f you have a tube rectifier socket, you can always buy or build a ss replacement to plug in.....

Be careful! Doing this will result in a higher plate voltage to all the tubes fed by the supply. You will need to replace one or more series resistors in the supply with larger value ones to bring the voltage down the design level.