Tom Lauten
89 posts
Jun 01, 2019
6:39 AM
|
Hi everyone.
My modded Chinese Princeton clone has a low (mains type) hum. It does not have this hum on the bench but when fitted to the cabinet it hums...LITERALLY no difference except the amp chassis sitting on a bench and 2ft wire going to the speaker, ...and the chassis mounted in the cabinet.
Could the speaker be picking up hum from power transformer when it’s in closer proximity in the enclosure? It’s the only real difference I can figure.
Can I fit a physical shield between them to reduce the hum? The hum isn’t very loud but I find it annoying because on the bench it is utterly SILENT.
----------
Tom "Bad Paw" Lauten
Loch Ness, Scotland
www.nimbacreations.com
Last Edited by Tom Lauten on Jun 01, 2019 6:41 AM
|
Prento
53 posts
Jun 01, 2019
2:45 PM
|
Hi Tom,
It could be related to one of the screws that hold the chassis to the cab possibly touching something it shouldn’t. If that is the case, it means that a component is being connected to ground when it shouldn’t. OR, it might be that you need to cover the timber that the open part of the chassis screws up to with foil to shield against electro magnetic interference. I think it will be something simple. Good luck.
|
STME58
2081 posts
Jun 01, 2019
5:12 PM
|
I am no expert in amplifiers, but in setting up lab equipment, improper grounding can cause all kinds of unexpected problems. Just curios, is you bench top metal? Might there be a difference in the way things were grounded between the setup on the bench and the setup in the cabinet? This is pretty similar to what Prento said, grounding is critical.
|
Tom Lauten
90 posts
Jun 02, 2019
1:23 AM
|
On the bench everything sat on a silicone rubber mat. I’ll look again but I’m certain the cabinet is all wood with the fixings not contacting any conductive materials. This is why I was suspecting the proximity of the speaker to the power transformer. As I said the hum is not loud and I could live with it, certainly not the worst ever heard.
----------
Tom "Bad Paw" Lauten
Loch Ness, Scotland
www.nimbacreations.com
Last Edited by Tom Lauten on Jun 02, 2019 1:24 AM
|
