|
Tubes Asylum Questions about tubes and gear that glows. FAQ |
|
|
|
Tubes Asylum Questions about tubes and gear that glows. FAQ |
|
In Reply to: Tube rectifiers: are they worth it? posted by Sunrise on March 27, 2004 at 20:06:46:
SS diodes have negligible voltage drop and can thus provide a "stiff" power supply (i.e. low sag). They turn on quickly, which can be a disadvantage because it provides power to the tubes in the preamp before they have heated up. Some people complain of switching noise ("hash") from SS rectifiers. This noise can be minimized by using soft recovery diodes, bypassing each diode with a 0.01uF 1000V AC capacitor and using a choke in the smoothing filter.Tube rectifiers don't give such a stiff power supply as SS rectifiers, because they incur a significant voltage drop (typically 40V or more). For a preamp, this is not likely to pose a problem because the current demand will be modest and unvarying. A tube rectifier needs a smallish smoothing capacitor (the first C in your CLC filter), typically in the range 8uF to 47uF, to avoid exceeding the tube's maximum allowable current and to keep the transformer reasonably cool. However, the capacitor following the choke can be as big as you like - say 470uF - to serve as a good reservoir and to compensate for the tube rectifier's lack of stiffness. In addition to all this, slow turn-on is a benefit of indirectly heated tube rectifiers (e.g. EZ81, GZ34), delaying the delivery of HT until the preamp tubes have warmed up.
This post is made possible by the generous support of people like you and our sponsors:
Follow Ups
- Re: Tube rectifiers: are they worth it? - Ray Moth 20:17:40 03/29/04 (0)
Top of Page ]
[ Contact Us ]
[ Support/Wish List ]
[ Copyright © 2025, Audio Asylum, all rights reserved ]
