• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

I really would like your help on my 300B project

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Jump to Latest
Ralph

Ralph

Member
Joined 2002
I got a little further this weekend and my amp and psu are near complete. I now use the STPS745F Schottky diodes for recification.

I also modified the filament and heater supply for the 300B and 5687 tubes. This is the result http://www.homepages.hetnet.nl/~rjonkers/psu.gif

When I connect my preamp and cdplayer, I still hear a little hum when I listen near my speakers. Is this probably because the whole thing is still on my workbench, of does a part of my PSU introduce this hum? What is the best way of investigating where the hum comes from?
 
dhaen

dhaen

Ex-Moderator
Joined 2002
keystrobe.co.uk/
Hum investigation

Hi Ralph,

If the hum is independent of volume setting, and of source connection, then it may be power supply or earthing.
If the hum happens only when the volume control is turned clockwise, it may be coming from the source. Try short-circuiting the input and check again.
If the hum appears the moment a source is connected, it could be earth currents. Make sure all equipment is powered from the same socket or socket group.

Ther's a few to keep you busy!

Cheers,

BTW Glad to hear you got your Schottky's connected finally.:)
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Top Bottom