Mains problems

[jeff mai]

I recently built a dead-bug style gain-clone. The sound is quite acceptable. One problem, however, is high susceptibility to garbage on the mains supply.

While listening I frequently notice ticks and pops. Today, it decided to blow several slow-blow fuses at power up until I turned off the overhead fan in the toilet. A hair dryer makes the toroid vibrate severely.

Anything to be done about this?

[cocolino]

While listening I frequently notice ticks and pops. Today, it decided to blow several slow-blow fuses at power up until I turned off the overhead fan in the toilet.

Jeff,

Motors can cause garbage on the mains supply and maybe Yours cause the ticks and pops - You could try a mains filter with the motor (or/and the amp.) .

Why the motor should/could be responsible to blow fuses in Your amp I have no idea. I don`t think the motor has something to do with this and the fuses blew incidentally while the motor was running. Maybe it is turn on surge problem (a turn on surge don`t necessarily blow fuses each time at power on) caused from the toroids (quite common) and You need sort of a soft start circuit .

Something like this:

http://home.swipnet.se/~w-50719/hifi...ida_sst01.html

A hair dryer makes the toroid vibrate severely.

The dryer very likely cause DC-voltage on the AC-line and is the cause that Your toroid vibrates.
Check this thread and use the simple DC blocking circuit for line application - this should cure it:

http://www.diyvideo.com/forums/showt...080&highlight=

[jeff mai]

Originally posted by cocolino
I don`t think the motor has something to do with this and the fuses blew incidentally while the motor was running. Maybe it is turn on surge problem (a turn on surge don`t necessarily blow fuses each time at power on) caused from the toroids (quite common) and You need sort of a soft start circuit .

No, I think the fuse blowing in the amp has to do with the motor running. I've had the amp for six weeks, switching it on and off several times / day and did not blow the fuse once. Today, the fuse blew twice during amplifier power up while the fan motor was running. After turning off the motor, it powered up fine with the same fuse value.

The ticks and pops I've noticed are only heard in one channel and are at times very frequent (1 / sec though not cyclical) and don't seem to be related to anything switching inside the house. I had the TV running earlier and could "see" the some of the louder ones as white lines momentarily appearing on the screen as I heard them through the speaker.

This is an old house and likely has really poor electrical service / wiring. I'm renting though...

[Nuuk]

It sounds to me as though you need to get your house wiring checked over. How old is the wiring?

[jeff mai]

I have no idea how old the house wiring is. Probably old.

I have wired a 0.1uf 275VAC X2 cap across line and neutral. It seems to have helped with some of the ticking sounds, but the larger pops still sail through to the speakers.

What else might I do?

[Nuuk]

What else might I do?

Put safety and commonsense ahead of hi-fi and have your house rewired!

[jeff mai]

Originally posted by Nuuk
Put safety and commonsense ahead of hi-fi and have your house rewired!

I'm very unclear as to what has convinced you that the wiring in my residence is unsafe. Beyond reciting the symptoms I described, perhaps you might educate me by describing the reason behind this concern? I'm not likely to initiate rewiring a house unless I know what problem I'm solving.

In any event, my only recourse to faulty wiring is relocation: I rent.

Can someone else offer a suggestion? I'm certain others have had problems with mains-borne noise entering their chip amps. It is interesting that these noises do not seem to afflict my valve amp when plugged in to the same mains socket.

[xato]

why don´t you try with a diferential trafo(like in tv psu)in the input ac?

[jackinnj]

Originally posted by jeff mai
I have no idea how old the house wiring is. Probably old.

I have wired a 0.1uf 275VAC X2 cap across line and neutral. It seems to have helped with some of the ticking sounds, but the larger pops still sail through to the speakers.

What else might I do?

go to the product descriptor on Nat Semi's website -- you might try one of the RFI cures -- putting a capacitor across the IN+ and IN- pins of the LM3875.

there are quite a few line filter descriptions on the web-- bifiliar windings etc. i have posted the schematic of one recommended for ham radio gear somewhere on DIYAUDIO but damned if I can find it