Need help with power supply for Pacific RIAA

[Dmeister]

Hello everyone. I just registered here since I'm getting into DIY audio. I just built the Pacific RIAA. Here's the schematic:


The thing is. I have no idea on what power supply to use. I'm not planning on anything expensive and my first idea was to buy something like a laptop charger or something similar. What i need to know is: How many volts and how much current do i need for a power supply for a project like this. Thanks ahead !

[bob91343]

It says 24 Volts but you can get by with a lot less. Almost no current draw so you can use a wall wart. Just make sure you put an electrolytic capacitor from +24 to ground.

[Dmeister]

Thanks a lot, man Would it work without the electrolytic cap ?

[leadbelly]

Originally Posted by Dmeister

Thanks a lot, man Would it work without the electrolytic cap ?

Where is there an electrolytic? They are all non-polarized.

[Dmeister]

Originally Posted by leadbelly

Where is there an electrolytic? They are all non-polarized.

There's no electrolytics in this schematic, although there is this schematic which is a slight variation and it includes a 2200uF electrolytic placed between ground and the +24V.

[leadbelly]

Originally Posted by Dmeister

There's no electrolytics in this schematic, although there is this schematic which is a slight variation and it includes a 2200uF electrolytic placed between ground and the +24V.

That cap is just the power supply filter cap. You don't need it specifically, BUT this circuit has poor PSRR, so you will need a good clean PS. Personally, I would use a 3 terminal regulator such as LM317 or LM7824.

[Dmeister]

I'm really, really new to all this. So basically if i put in the 2200uF cap, the sound will be somewhat better, right ? Will it make a big difference in sound quality ?

[leadbelly]

Originally Posted by Dmeister

Will it make a big difference in sound quality ?

That is a complex question to answer, and I think you will just get confused.

At the risk of oversimplifying, yes I can see where Bob would recommend that if you are going to use a laptop charger, then use a big filter cap to get as much ripple out of the supply as possible.

[Dmeister]

But it would still work relatively good without it ? I'm no audiophile so i probably don't have ears accurate as say, yours. So I probably won't notice too much of a difference.

[leadbelly]

Originally Posted by Dmeister

But it would still work relatively good without it ? I'm no audiophile so i probably don't have ears accurate as say, yours. So I probably won't notice too much of a difference.

For that circuit, if you don't have a good low ripple supply, you will hear lots of hum, and you won't need golden ears to hear it! That being said, sure, leave the big cap out and report back when you try it out.