fire up Aleph 30

[wijgers]

Hello Andrea,

Thanks for the complements

I use one bridge for each transformer. I use two transfermers rated at 300VA 2x 18 V secondary.

The plop is pretty loud and the woofers are at the max when the plop occures.

Nils

[Panelhead]

Originally posted by wijgers
Hello Andrea,

Thanks for the complements

I use one bridge for each transformer. I use two transfermers rated at 300VA 2x 18 V secondary.

The plop is pretty loud and the woofers are at the max when the plop occures.

Nils

That "plop" is not good for your woofers. I used a switch on the output to solve this. It is a dual on-on switch. One position goes to the speakers, the other to a power resistor.
This way a 25 watt 10 ohm resistor gets the power up and down transients. If you solve this issue, the resistor can be left on the on position.
The dual switch is used to place the output on two sets of contacts. Less likely to open.
There are much more elegant ways to do this. But it works for me.

George

[Andypairo]

Originally posted by wijgers
Hello Andrea,

Thanks for the complements

I use one bridge for each transformer. I use two transfermers rated at 300VA 2x 18 V secondary.

The plop is pretty loud and the woofers are at the max when the plop occures.

Nils

Try using 2 bridges per transformer and add the thermistor, it will help you avoiding turn-on surges.

Cheers

Andrea

[wijgers]

I'm using one rectifier bridge per transformer, and made of 4 MBR1090 Diodes. Rated at diodes 90 V and 10 A. Are those diodes not fast enough or are other characteristics not good for my amp?

There still is a little hum and when I connect - input at gnd it gives a louder hum (50 Hz). this Hum I can hear at 2 meters.

The rectifer bridge is not cooled yet, but will be soon. For the rest I don't see any troubles where the hum can be produced from.

What can I do to reduce the hum.

RCA connected or disconnected gives no difference.

Nils

[wijgers]

Andrea,

You sugest to use 2 bridges per transformer, so I need 4 rectifier bridges in this amp.

Didn't change anything yet due some lack of time. Probably this weekend I will try to add the themistors an change the gnd schematics. like I saw at the aleph 5 gnd problem thread. Maybe there is a pickup from the vibrating transformer. When everything wasn't not in a box I did still hear some hum.

nils