what DOES 1% or .2% whine sound like

 

i tried one of those noise filters and they did nothing for me...


thanks for bringing this thread back. i was shifting my amp the other day, and i think i crossed the input cables across something because my whine has come back (though not as loud). i need to get back there and shift the cables around to see if i can nail down what the culprit actually is...

 

I assume this was directed at my comment, although I can't be sure. What I mean is, if a filter is designed to remove an alternator whine (or some other noise), the noise is obviously in the audio frequency range. The filter cannot notch out JUST the noise, but also destroys any REAL audio in the same notched area, thereby creating a hole in the music. Alternator whine solved, but music destroyed in the process. And since these filters will have a very low slope (maybe 3-6 dB) to cut out noise in a wide band, you've also removed a large chunk of music, as well.

 

When I added my second amp to the Subaru, I occasionally get a VERY high pitched whine. It only occurs when my rpm drops below 1k. I'm sure you're experiencing a similar problem in your 1% which is basically the alternator not producing enough power to run everything + the audio, which is going to be a problem with most smaller cars that don't run a true 14.4v

 

comment from the peanut gallery...

i think the .2% comment was in reference to...


[QUOTE]Originally posted by 2K3S2000
[B]I was having a similar problem with my S, and yes modifry is correct on all of the suggestions he gave.

 

oh & btw, I'm glad that you listened to someone, mgiang7, and moved that amp and cables around... I thought you were going to fight me over PM's!!

 

[QUOTE]Originally posted by PJK3
[B]comment from the peanut gallery...

i think the .2% comment was in reference to...


also, another potential way to pull out whine/noise in a pre-amp noise situation is to run balanced cabling (ie, think XLR) from the head to the amp.

 

hmm, i can't think of many headunits that have balanced outputs. i noticed that hifonics XI line has a breakout box where you feed it rca and then it outputs balanced line out (via a din cable) to the amp.

now does it really make a difference? if you don't have balanced from the head, how much help would it be?

 

go to radioshack and purchase a ground loop isolator ($15).

 

well, it can be a helpful if you are experiencing some sort of ground loop or RF interference as balanced cabling can essentially eliminate a great deal of that kind of noise. it's why you see it used virtually exclusively in the professional sound field.

it is a bit over the top for cars, but not completely unheard of... years ago (circa '95) i purchased a 4-channel Adcom car amp (long since mysteriously discontinued), and it only accepts XLR inputs. no other amp's come to mind that accept XLR inputs, and i know of no headunit that outputs XLR.

i never experienced a problem w/ noise in my current vehicle, so i just have RCA to XLR adapters at the amp, but if you were to run XLR in your vehicle - the best way to do it would be to convert to XLR from RCA almost immediately after outputing from the headunit, and then to convert back just before you pass into the amp. if you are using an active crossover, you'll have to deal with it as well. if it's close to the headunit, go RCA straight into it and convert to XLR right after leaving. if it is very close to the amps, you can probably get away with a short run of RCA.

if you think about pursuing this route, we can go into more details later, but be aware that balanced cable and converters don't always come cheap.