Tube DIY Asylum Do It Yourself (DIY) paradise for tube and SET project builders.

---

[ Follow Ups ] Thread: [ Display  All  Email ] [ Tube DIY Asylum ]

---

[ Alert Moderator ]

---

Re: Phono preamp - odd capacitor question - picture

Posted by Rob Mercure (A) on March 20, 2007 at 10:33:29

In Reply to: Phono preamp - odd capacitor question - picture posted by PeterI on March 19, 2007 at 09:06:53:

Pete,

Can you provide a topside picture of your preamp? I'm pretty sure that I've got the "same thing" 'cept some of the parts seem to be spaced a bit differently and mine uses "King" brand oil caps.

If we've got the same unit then your's has only a 1/2 wave rectifier (1 diode) with 60 Hz ripple - changing this to a full wave bridge will more or less double your filtering. Also the tube heaters aren't referenced to ground nor to a positive source. Adding a "synthetic center tap" - that is, two matched 100 ohm resistors in series across the heaters with the mid point where the resistors are soldered to each other either connected to ground or to a positive source through a voltage divider should help your noise level a bit.

Otherwise there really isn't much more you could do with this chassis 'cept perhaps add a choke to the power supply bolted onto the output side - but you'd have to experiment to determine whether the choke radiated more hum than it eliminated.

Rob

This post is made possible by the generous support of people like you and our sponsors:

Atma-Sphere Music Systems, Inc.

---

[ Top of Page ] [ Contact Us ] [ Support/Wish List ] [ Copyright © 2024, Audio Asylum, all rights reserved ]

---

[ General ] [ Speakers ] [ Tubes ] [ Vinyl ] [ Digital ] [ Hi-Rez ] [ Video Asylum ] [ Cables ] [ Tweaks/DIY ] [ Music ] [ Films ]

---