Aleph5 sound

[vossie]

My newly finished Aleph 5 has a silght hum in the one speaker when switched on - not much but I don't like it. This disappears after 10 min or so when a the heatsinks have started to warm up a bit.

Any ideas what this could be? Should I STRESS about it

The LED is attached between minus and ground - I can move it to the other side to check but doubt it. Could there be a faulty cap or something? The voltage rails are exactly 36.1V plus and minus (Aleph5 specs are 34V). Test voltages are all fine as per service manual except for R11 which is 6.1V for both channels (specs are 4-5V) - don't think I need to worrie about this.

For the rest I have to say that the sound is incredable once warmed up.

Vossie

[ElectroNick]

Hi Vossie,

Have you checked the ripple voltage over the caps ? Maybe a few extra caps, parallel over the big ones would help a little.
However if it disappears after 10 minutes it's more a temperature thing. All fets (input and output stage) correctly mounted ? Heatsinks isolated ?

What caps did you use on the Aleph board for the 220uF ones ?
Have you experimented with them ?
I've got one channel completed, can't give a good judgement yet.
It seems however that it plays a bit flatter in the high freq's compared to my current amps.
Could it be these caps ? Or should i wait till both channels are built and then review my opinion ?

Grtz
Nick

[vossie]

Hi Electro-Nick,

Thanks for the reply. I have not done anything to trace the hum but will tonight so I can't say

The fets are OK, The ouput sound is very good and balanced - I don't think this will be the case if one of the fets rest in peace (or pieces) due to some or other misshap...

I have used normal electrolytic 220uf caps. If it were these (or one of them) why would the hum disappear after a while?

I must say that it sounds like 50/60Hz so somwhere the PSU ripple must leak through.

BTW: Don't bother listening to one channel only AND don't judge it before it has warmed up! Even the Aleph 30 (original) sounds completely different once warmed up. Relax and get the other channel done - we'll chat again...

SV