Build Your Own Arcade Controls Forum

Main => Main Forum => Topic started by: Jamesbeat on March 29, 2016, 12:28:46 pm

Title: Is this just asking for ground loop hum?
Post by: Jamesbeat on March 29, 2016, 12:28:46 pm

I ordered some binding posts and banana plugs, and a female Molex cable.
My plan is to drill holes in an expansion card blanking plate, mount the binding posts into it, and solder on the Molex cable.
This will be a nice tidy and non destructive way to tap into the computers power supply, and will also be easy to move to a new pc if I upgrade.

I'm definitely going to power my marquee and coin door lights with this, but I'm also toying with the idea of powering my amplifier with it too.

I've read a couple of posts about ground loop hum, and I'm wondering if powering the amp in this manner is wise?

Title: Re: Is this just asking for ground loop hum?
Post by: P.H.U. on March 30, 2016, 12:25:10 am

Seems unavoidable that you will encounter ground loop hum when powering your sound amp using the same PSU from your computer. In any case, seems easily resolved with one of these (http://www.amazon.com/PAC-SNI-1-3-5-3-5-mm-Isolator/dp/B001EAQTRI/ref=sr_1_4?ie=UTF8&qid=1459311790&sr=8-4&keywords=ground+loop+isolator).

Title: Re: Is this just asking for ground loop hum?
Post by: P.H.U. on March 30, 2016, 12:39:48 am

BTW, what amp are you going to use? I have been reading a ton on the TDA7297F-based amps.

Title: Re: Is this just asking for ground loop hum?
Post by: Jamesbeat on March 30, 2016, 10:13:58 am

It's a Lepai LP-808, which cost less than that ground loop isolater :D

It's a decent little amp though, perfectly good enough for arcade cab use.
It goes WAY louder than I need it to with no distortion that I can discern.
I'm currently running it on a separate wall adapter, but I'm hoping to use it on the pc Psu to keep things simple.

If I can do away with the separate adapter, the whole cab will be running off the pc Psu, which means that everything will start up and shut down with the pc without me having to mess around with smart power strips etc.

Title: Re: Is this just asking for ground loop hum?
Post by: yotsuya on March 30, 2016, 10:53:56 am

You're not running a pro home theatre 7.1 setup? GTFO.

Title: Re: Is this just asking for ground loop hum?
Post by: Jamesbeat on March 30, 2016, 12:09:16 pm

Quote from: yotsuya on March 30, 2016, 10:53:56 am

You're not running a pro home theatre 7.1 setup? GTFO.

I did initially, but I had to put the rear speakers in my back pockets, and the bass made me $hit my pants at certain frequencies.

Hearing Donkey Kong in full 7.1 was really something to behold though.

Title: Re: Is this just asking for ground loop hum?
Post by: yotsuya on March 30, 2016, 12:10:24 pm

Quote from: Jamesbeat on March 30, 2016, 12:09:16 pm

Quote from: yotsuya on March 30, 2016, 10:53:56 am

You're not running a pro home theatre 7.1 setup? GTFO.

I did initially, but I had to put the rear speakers in my back pockets, and the bass made me $hit my pants at certain frequencies.

Hearing Donkey Kong in full 7.1 was really something to behold though.

Reminds me,  I need to make a Brown Note badge for ZapCon...