ground or lack thereof
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Posted on Aug 23, 2007 02:06 pm
jetglo
Member Since: Jul 23, 2004
OK OK OK.. I solved my own problem as I was posting this msg.. But I should post this anyway.. get some feedback.
Here's the original post I almost sent:
<<This problem is so basic and lame it is really pissing me off.
I am trying to hook my computer to my home stereo.. an Onkyo amp/radio with rca's for phono (which appears to have some kind of boost or preamp) and for cd player.
Ok.. 1/8th inch stereo plug out of computer to rca's into the amp's CD inputs. I get a ground hum. Into PHONO I get an even louder hum.>>
OK so as I was typing I thought maybe I better look on the back of the receiver.. so I pull it out of the cabinet.. no easy task.. and Voila- RCA's for tape in/out..(forgot about those).. I try it out going to tape inputs.. great no hum.
OK I am curious though.. why is this so?
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Aug 23, 2007 02:11 pm Could be that the RCAs weren't firmly pushed in all the way - that'll create hum.
Whoa, never use the phono input for a line level signal. That input has a much higher amplification level, plus a built-in RIAA EQ circuit for vinyl records only.
Aug 23, 2007 02:12 pm The phono input is easy, phono's have real grounding issues, that's why they all have that extra little wire that needs to be connected to the system's ground...
I suspect your receiver just doesn't have a great ground in it...or your house/apartment doesn't...
jetgloMember
Since: Jul 23, 2004
Aug 24, 2007 04:32 am well, before I tried just the cable to to the receiver I was trying to get a selector that I built to work. But happily all is well.. I built a selector so that I can switch between computer speakers or stereo receiver so that I can better try my hand at mastering with HarBal. I left some room on the project box so that I can add more speaker options. I am just glad it was only the choice of RCA inputs that created the problem and not my selector or some greater problem like the computer or receiver.
glnflwrsHead KnockerContributor
Since: May 20, 2007
Aug 24, 2007 04:53 am Tape in/outs are regular, industry standard Line Level inputs as are PC Line Outs, whereas phono and CD inputs are at a lower, non-industry standard level. (Not Mic or Line Level). A PC Line Out is too high for phono and CD inputs and the hum is from that high level being pushed into preamp circuitry.
BTW, I built the same type selector for my connection to my stereo. Works great, huh?
Aug 24, 2007 10:22 am Quote:
CD inputs are at a lower, non-industry standard level.
Really? I didn't know that. The CD inputs on my home theater system seem to have the same gain as the Aux, TV and Tape inputs. Hmm.
jetgloMember
Since: Jul 23, 2004
Aug 24, 2007 05:06 pm yes it is great! I am looking forward to adding more types of speaker situations.
