Warning for DacMagic owners (PSU related)

[Fidelity Audio]

Hi Brent,

How does it get +/-15V from 12V AC with no centre tap?

There is a bridge and capacitor network that boosts the voltage to +/-30V. This voltage does fluctuate from dac to dac though.

With a 9V tx the voltage drops 8-10V and the unit no longer cooks

Brent

 

[Glenn2]

Ooh nice one Brent. As they are only fifteen squids, I might pop back to Mappo's and get the 9V version of the one I got last week.

If I've still got the receipt, they might even let me swap.

 

[Fidelity Audio]

Hopefully it will be higher current too

Brent

 

[jackinnj]

Hi Brent,

How does it get +/-15V from 12V AC with no centre tap?

Not that it's the way that they necessarily do it, but...

You use a voltage doubler circuit -- and pull the ground from the junction of the two capacitors. You can use a "rail splitter" -- like the TLE2426.

 

[Glenn2]

Yes, 3.2A vs 3A.

My local branch has 2 in stock too.

 

[Fidelity Audio]

Jackinnj

Yep thats exactly how they do it. Much better diagram than the naf one I was drawing up lol.

They use 4 diodes though and 2x 1000uF caps. After the resistors they have 2x 2200uF caps for another part of the circuit.

Brent

 

[Glenn2]

Great, thanks guys.

No switchers then. 🙂

 

[Fidelity Audio]

Yes, 3.2A vs 3A.

My local branch has 2 in stock too.

200mA is better than a slap in the face 😉

No switchers thank god

Brent

 

[Glenn2]

Interesting thread over at the tent too...

Link...

 

[Fidelity Audio]

Ah yes. I have informed them of the 9V tx too 😀

Brent