Aleph 5 wiring question

[PedroPO]

Hi all.

My aleph 5 is at is "final production" stage.
yesterday night I tested it with all the chasis assembled and i noticed some minor buzzing sound coming from the tweeters.

I realized that the connections between the boards (from kristijan) and the PSU were very important.

Example:

I first wired the minus input to the ground(unbalaced operation) of the PSU at the capacitor - result lots of hum. then I connect it to the ground at the input RCA and the hum significantly reduced.

Kristijan by mistake posted this picture.
should the overall wiring be like this?

[Mad_K]

where is the AC ground connection?

[jleaman]

humm was the humm there befor man..

id be interested too because im at the stage of building mine into my chassis now..

just a quick question im substuting irfp140's insted of 144's is there any problems..?

Jason

[Mad_K]

no problemo with irfp140 instead of irf/p144.

The way I have connected my Aleph, is with AC ground -> NTC -> chassis. All grounds is taken from this point in the chassis (star grounding). Absolutely no hum.

[mefinnis]

Originally posted by Mad_K
All grounds is taken from this point in the chassis (star grounding). Absolutely no hum.

Someone correct me but I thought the reason for using the NTC in the earth line was to raise the circuit ground several ohms above the chassis/mains ground. That is the mains should earth to the chassis, then the circuit earth should connect to this point via the NTC .... ??

My description of this comes from the construction notes for the Balanced Line Stage

Earth ground from the AC cord is attached to the chassis for safety, and is connected to the circuit ground through a power thermistor (bright idea from Frank DeLuca). This gives some resistive isolation for prevention of ground loops but goes to small values of resistance in case of catastrophic connection to the live AC line.

cheers,
mark

[Peter Daniel]

Originally posted by mefinnis
Someone correct me but I thought the reason for using the NTC in the earth line was to raise the circuit ground several ohms above the chassis/mains ground. That is the mains should earth to the chassis, then the circuit earth should connect to this point via the NTC .... ??

No need to correct, that's the way I did it too, but I have hum as well.

[trigon]

What about the XLR jumper in between G & - .

Or having ground point (star) after NTC that comes from AC ground, if you reed carefully Mad_K note, not on the Capacitors board it is a big no no. :-)

The way I have connected my Aleph, is with AC ground -> NTC -> chassis. All grounds is taken from this point in the chassis (star grounding). Absolutely no hum.

That is exactly what I am going to do.

Trigon.

[protos]

My impression is that the circuit and LS ground is on the 0 point on the caps then you ground that point to the chassis thru a thermistor where the AC ground is.

[PedroPO]

Hi all!

I kinda solved my humm problem.

In fact the humm is gone, but the problem is STILL in my head

I said that I connected the minus input to the PSU ground.

That is true.

My PSU ground is in between two caps wich are connected witha Y cable connected to the bridge rectifier.

I have also a ground wire that comes from the board and is on one of the capacitors, so electrically connected to the other via the Y cable.

IF I CONNECT this wire to the cap with the ground wire, all is fine.

If I CONNECt the wire to the other cap (that is electrically connected) a good humm appears..

WHY????

This appened in both channels.

[PedroPO]

LET ME PUT IT IN SIMPLE WORDS

The blue solid line is the no humm config.

The blue dashed line is the hum config.

IF anyone knows why, please tell me. I believe in magic now!