My new mini Aleph

[Netlist]

/Hugo

[PSz.]

Ummmm....

Now my humming mini aleph doesn't hum when the inputs are shorted!

However, it still hums whenever ANY source or combination thereof is connected to it. But it is dead silent with no source connected. So I've been reading everything I can get my hands on, thinking, meditating...

Then I came across this www.raleighaudio.com/chapter_3.htm page and it got really interesting starting with

"The cause of the buzz was harder to find. At first I thought that I had a ground problem, "

Now I have to ask (sheepishly) if having my gate stopper resistors too far from the mosfets could cause LOW frequency hum/oscillation only when connected to a source. The leads are currently 2 inches long on the left channel and 4 inches on the right.

I haven't smoked my compression drivers yet. And they are connected directly to the amp in an actively crossed system so I don't know if it is oscillation.

Oh , I don't have a scope. So if any one in the SF Bay area has a scope and is interested I would be forever grateful for help troubleshooting.

any thoughts on the gate stoppers?

much thanks,
PSz.

[PSz.]

Update:

I went ahead and relocated the gate resistors at the same time that I changed over to to-3 output devices. The amp takes much longer to warm up now, so I assume it was oscillating before.

However, there is still some humming. I think I'm getting very picky now because the hum is below the noise floor of most recordings. I pulled a Bryston amp out of my mothball fleet and it is much noisier than the lil' Aleph. But I will continue searching for ways to make it quieter. All suggestions are welcome.

regards,
PSz.

[PSz.]

Here is a quick picture. Hope it's not too big to attach...

[BillWW]

I am also using 110 plus Db/w compression drivers and found using a single transformer causes hum.

High efficiency speakers pick up the slightest hums or noises very easy. A conventional speaker would not notice these minor hums.

I ended up going dual mono power toroids and that seemed to isolate the ground loop that you have.

I also isolated the common rail ground with a bridge rectifier. I ran channel 1 toroid to the 1 ac side and the other channel 2 to the other ac leg and grounded the plus and minus to the chassis and ac outlet ground. So far that seems to keep the ground loop isolated. I do not know if you could isolate your grounds with only one toroid, so that was why I ended up using a second one to get rid of that annoying hum.

I was still getting some noises, which I believe were from my star ground being tapped too close to the capacitor bank, so I am experimenting with moving my star ground away from the capacitor bank.

Good luck!

[still4given]

Try this tip from Leach's site:

If you are sure that the hum is due to an internal ground loop, the procedure for breaking this loop is as follows:

Turn the amplifier off and wait for the power supply to discharge. Do not perform this procedure with the amplifier on.
Cut the wire to the central ground on the input side of one circuit board.
Solder a short circuit jumper wire between the ground lugs on the two input jacks.
The circuit board with the cut ground wire is now grounded back through its input ground lead to the ground of the other circuit board. Use an ohmmeter to verify the new ground connection before turning the amp back on.

Worked for me.

Blessings, Terry