[Leicachamp]

Hi I am using a Amphora with GS1000i's. There seems to be a lot of background noise when used in the high gain setting. Also there is a buzz/hum whenever I touch the volume knob or any of the metal switches at the back.

Is this normal, if not is it an earth problem.


Thanks for any feedback.

 

[kboe]

Why use the GS1000s in high gain? I have noticed the hum when touching metal parts of my past amps, but only when I had built up a static charge, (wearing socks on carpet).

 

[Leicachamp]

It may be an illusion, but i felt the high gain settings had more dynamics.
The hum is not from static. The hum stays as long as i am touching the metal parts. Disappears as soon as i remove my fingers off the metal.

 

[kboe]

Well the second problem, (the hum) is solved by not touching metal parts on the amp.

If you try the headphones on low/no gain dose the background noise stay? Ken, anybody else?

Kevin

 

[Vinnie R.]

Hi Guys,

This is actually "normal" and no need for concern.

Depending on the source you have connected to your Amphora and the grounding of the source (the source's RCA ground relative to power ground of the AC powered source) - yes, it is possible that you can create a small ground loop when you touch the knob and this gets amplified by the amplifier section (and it is heard more on high gain because the loop noise is amplified more).

One reason for this is because the Amphora is off the grid and not connected to AC power (even when the charger is plugged in, the power switch completely disconnects it from the circuit). The other reason (probably the main reason!) is because it is in a wood chassis, so the RCA grounds of the Amphora have not continuity (via metal) to the volume control shaft/knob.

I suppose a wire can be ran from the RCA ground to metal shaft of the Goldpoint and this might solve the ground loop because the knob and the RCA ground of your source would all be at the same potential.

As far as high gain vs. low gain, if you can can use low gain and get the music loud enough by the time the volume knob is at max, this is ideal and will offer reduced noise (less gain = less noise). Regarding dynamics, the extra gain should not make a difference. The extra gain just makes the volume louder at a give setting on the volume knob, but if you don't need it to be louder (i.e. if you have more sensitive headphones that play louder with less power), then you might not need the added 12dB of gain.

Hope this helps!

Vinnie

 

[kboe]

Ahhhhhhhhhhhhhhhhhh!

 

[Leicachamp]

Thanks Vinnie. All is understood.



Quote:

Originally Posted by Vinnie R. /img/forum/go_quote.gif Hi Guys, This is actually "normal" and no need for concern. Depending on the source you have connected to your Amphora and the grounding of the source (the source's RCA ground relative to power ground of the AC powered source) - yes, it is possible that you can create a small ground loop when you touch the knob and this gets amplified by the amplifier section (and it is heard more on high gain because the loop noise is amplified more). One reason for this is because the Amphora is off the grid and not connected to AC power (even when the charger is plugged in, the power switch completely disconnects it from the circuit). The other reason (probably the main reason!) is because it is in a wood chassis, so the RCA grounds of the Amphora have not continuity (via metal) to the volume control shaft/knob. I suppose a wire can be ran from the RCA ground to metal shaft of the Goldpoint and this might solve the ground loop because the knob and the RCA ground of your source would all be at the same potential. As far as high gain vs. low gain, if you can can use low gain and get the music loud enough by the time the volume knob is at max, this is ideal and will offer reduced noise (less gain = less noise). Regarding dynamics, the extra gain should not make a difference. The extra gain just makes the volume louder at a give setting on the volume knob, but if you don't need it to be louder (i.e. if you have more sensitive headphones that play louder with less power), then you might not need the added 12dB of gain. Hope this helps! Vinnie