Hum problem with jfet Aleph 3 (babbelfish)

[cviller]

Following steens advise seemed to lower the noise noticeable. Shorting the inputs removed hum completely... cool!

I can hear a tiny hiss from one channel, but that channel is without the RC mumbojumbo - seems like a god mod for my fish.

Now I'll box it up and see if the hum can stay away.

 

[steenoe]

Shorting the inputs

What excactly do you mean?? You are not supposed to short any inputs (or outputs)
Sorry to sound harsh, but........

Steen

 

[Zen Mod]

Following steens advise seemed to lower the noise noticeable. Shorting the inputs removed hum completely... cool!

I can hear a tiny hiss from one channel, but that channel is without the RC mumbojumbo - seems like a god mod for my fish.

Now I'll box it up and see if the hum can stay away.

http://www.diyaudio.com/forums/showthread.php?postid=1123832#post1123832

http://www.diyaudio.com/forums/showthread.php?postid=1123832#post1123832

I don't wanna even remember nightmare I have several yrs ago ,when I build custom 2way toob xover for Klipsch Horns........

I build it 3 times,chasing how to eliminate hum.

don't ask me what was culprit........it wasn't logical at all.

you are just plain lucky with these trivial problems , trying few minor variations of grounding

 

[cviller]

If the input is simply floating, I think it makes sense there will be noise.
Unless the cables are perfectly shielded, but they are not, when nothing is connected to the amp...

 

[Zen Mod]

What excactly do you mean?? You are not supposed to short any inputs (or outputs)
Sorry to sound harsh, but........

Steen

you tease cviller ........or?

just one smiley in your post leaves me somewhat suspicious

 

[steenoe]

OOOOkay, to avoid any more confusion, I think we should let cviller have some peace, so that he can implement the lead's I suggested At this point, I think one step ahead is the best!

Steen

 

[cviller]

I have implemented it, but hum is only gone when input is not floating... haven't tried connecting it to my preamp, but my hopes are high.

 

[steenoe]

Please, bring that amp to me this sunday when you drop by anyways And please, come as early as you can. These things takes time, as you know!! I dont care, but your girlfriend might

Steen

 

[cviller]

I will bring it, but it's fixed!
I can hear tiny tiny hum from one channel at ~10cm from speaker and <5cm on the other. (The difference is due to a rc filter on input pair on one channel which is not there on the other)
I can also hear tiny tiny music signal from another channel on the preamp if I turn up volume - so I think my amp is the strongest link now.

I think noise entered chassis somewhere and wired to signal ground through rca connectors.

UPDATE:
The amp is warming up and I cannot get my ear close enough to hear hum on good channel the other is almost as silent.
I cannot reproduce the preamp music from another channel, so I guess I was just hearing things...