[Gaffer74]

Hi.
I have an MF X-cans headphone amp that is unaltered internally (bought 2nd hand).
I've made some cosmetic changes, namely new aluminium volume knob and top and rear ventilation holes only:

The power supply wall wart is also stock standard.

I've noticed that even at moderate volumes, I can hear a low hum/lo grade buzz in the background through the headphones. The amp itself is quiet and situated away from other components including the p/s.

My question is, what is most likely to be causing the hum?

The amp has been unaltered since first sold (it's a v1) so I assume the valves are the original philips ones that are in there now.

Do I:
a; change the valves to get rid of the hum?
b; build/buy a new power supply to get rid of the hum?
c; replace all the caps internally to get rid of the hum?

(last two options courtesy of reading the rock grotto site...very helpful

)

Thanx
Gaffer

 

[mrarroyo]

To me hum is ussually related to a ground problem. I would check that before I start messing wiht the amp.

 

[Gaffer74]

Thanx.
To be specific, if you put your ear against a p/s, you'll probably hear a low hum from the toroid.
Well this is the same low "buzzing" I'm hearing, but it's through the headphones only

(not heard when ear against the amp itself).

I did actually run what I thought would be a grounding wire from the chassis of the x-cans to the chassis of the source compnonet, but this did nothing so I removed it.

You're right, I wouldn't be surprised if there is an earth loop somewhere what with me having CD player, valve amp, valve headphone amp, vinyl deck, pre-preamp, phono amp etc etc all hooked up.

Anything specific I could do to check?

Thanx

Gaffer

 

[Gaffer74]

Aaaah, it seems to have sorted itself out.
The amp was exclusively used for my AV setup from the DVD system.
I bought it home to my secondary Hi-Fi system and plugged it into that instead...also using different 'phones (HD480II's rather than HD575's)....and that's cured the problem.

No hum/hiss/buzz...inky black silence between notes...great

.

May well have been a mains issue / earth loop in my flat then.

Thanx for your help

 

[mrarroyo]

Quote:

Originally Posted by Gaffer74 Aaaah, it seems to have sorted itself out. The amp was exclusively used for my AV setup from the DVD system. I bought it home to my secondary Hi-Fi system and plugged it into that instead...also using different 'phones (HD480II's rather than HD575's)....and that's cured the problem. No hum/hiss/buzz...inky black silence between notes...great . May well have been a mains issue / earth loop in my flat then. Thanx for your help

It sound like there was a ground issue with one of the previous components. Glad it was resolved.