[Felipe]

So this is one more topic about hum in the audio chain...sometimes too small to give a notice and others just ... NOT!

I have had quite a fight with GK1 in the past, trying to get the hum out of it. I managed to route the cables and got a wooden box in order to have "manageable" hum. That means that i have very faint hum when the pot is in low volume, and it increases as i turn the volume up. As the "music/signal" also increases the ratio signal/noise remains the same and almost unnoticeable, and only heard at the quietest music passages.

So i here now face a new problem, dont know if it has a solution. I decided to put the GK1 in my home cinema system, between the AV processor and the AKSA amp. So to achieve this bypass i must have the volume pot turned all the way up. And so...i have noise. Lots.

The goal here is add valve sound to the system so i want all the signal of the gk1 in the chain.
Could the noise be originating from the internal input wires? Maybe shielding them would be a good choice. Noise is more apparent when no cable is connected to the GK1 input...so the AV is reducing its noise a bit with its mass...
Do give a thought
Filipe

[AKSA]

Felipe,

Ah, hum, the perennial problem.....

If the hum is before the volume control, it is coming from the SS gain block, not the tube.

I will give this further thought.....  it's tricky, I agree.

Hugh

[VYnuhl.Addict]

Hi Filipe,

    Hum is a huge PITA, especially in a preamp  which is compounded further by the fact most transformers are usually enclosed within the same box. I have overcome some input hum problems in the past by either careful routing and or using a metal enclosure which is also grounded to the star ground from the chassis( all inputs and output jacks being isolated), youll find more often than not you will have more hum problems with a wood enclosure. Failing the careful routing, or impossibility to do so, Ive always solved this issue with small gauge coaxial cable, this is well shielded and of very low capacitance for video/satellite reception use between the output of the pot and the preamp, this is the most critical point. The wire from the input to the volume pot doesn't matter too much, no need for shielding but wouldnt hurt to do so...



Hope this helps.
Colin