I've got pretty much the whole setup ready to go. I'm still waiting on the box for my sub, but I have all the wiring ready to go.
I've been listening/testing my components and trying to tweak the amps for optimal settings.
I'm getting a hissing sound through my set of Infinity Component speakers. -On FM and MP3 modes -Volume all the way to 0, doesn't make a difference. -The hissing does not increase when volume is increased. -Turned equalizer off on the HU. Tested with loud on/off, still same hissing. -Amp set to 0 gain or a quarter of a turn, still same hiss. -I've only tested while the car is off.
I believe the gain is the only thing I've messed with. It's a Rockford Fosgate R300-4.
I have it on AP, 0dB punch bass, rear gain is set to 1/4 turn. The speakers are setup bridged on the amp.
Is there anything I can do? I don't mind it so much as when I turn it up, the speakers sound fine and the hiss isn't audible at higher volume.
Ok so I don't have to remind you that amp gain should be set as low as possible and I assume you are familiar with the different gain setting procedures.
Disconnect the RCAs from the amp, set the amp gain to 0, the noise is still audible?
If it is then just if your components have attenuation for the tweeters use that, nothing more you can do.
If the noise stops then reconnect theRCAs up the gain, defeat all tone controls in the HU/signal processors you may have, if you can't control the noise then you need to get better/modern HU/signal processors.
I have some FAQs written for this sort of thing at caraudio.glasswolf.net However, in the mean time, this is either most commonly caused by a ground loop, RFI, or the amp gain being set too high. In your case, I'd make sure everything has a solid chassis ground to sanded bare metal, not to a seat bolt, or painted chassis point, and make sure all connections are tight and secure. Next, be sure that none of your signal path lines are running anywhere near the crossover modules for the components. crossovers and ignition system wiring are the two things most often guilty of injecting noise into your system.
power and signal can be together, as the lower the volume, the lower the current draw, thus you won't have enough current to produce noise that would be audible over the sound of the stereo itself, however crossovers, due to the capacitors and chokes, and ignition systems due to the high current and the plugs or coil packs, will induce noise.
I haven't had a chance to test your recommendations. Just got the box and sub hooked up today.
The grounds are going to a body bolt and have been sanded/grinded with a dremel. I made sure to go extra large on the grinding of the paint to make sure that it was a solid ground.
I have the gain set to 1/4 turn right now. Even with the gain set to 0 it still hisses. So I put back to 1/4 because the bass is so overpowering.
Crossover modules? Sorry for being a noob, but I don't believe I have any crossovers that I know of, unless that is the device that is sending the signal from the components to the amp. It's a little box that takes both sets of speaker wires from the components and runs 1 set to the amp from each box.
I have the power wire to my HU hooked up to my ignition so that it only turns on when I have my key in the "on" position. The constant power/memory wire is hooked up directly to a main always on positive connection directly connecting to the battery.
try grounding the headunit directly to chassis, and not using the wiring harness ground. that is a common issue as well. If you have separates, you'll have a midrange speaker, a tweeter, and a small box that splits the frequencies to each of the speakers that goes between the speakers and the amp.. that's the crossover (XO) If you use coaxials where the tweeter is mounted in the same unit as the midrange, then don't worry about it.
So I have the ground from the HU wiring going to a chassid ground, how would I ground the HU while not using the supplied wire? Would I just loosen a screw on the unit, and run that to a ground?
I'm using regular speaker wire on the tweeter and mid, I'll check the wiring to make sure nothing is touching.
I'm going to try the RCA test today, and see if I can ground the HU directly. I really have a feeling it's the HU since it's a retrosound.
just take the black wire from the HU and ground that wire directly to the chassis instead of using the ground wire in the factory wiring harness. that's all. That factory harness snakes all over the place behind the dash, often making the ground wire several feet long, and sometimes running near to the wiring for the ignition system, which would induce noise.
Well, I have a 1964 Volkswagen Beetle - so there isn't a factory wiring harness. I ran all the wiring myself.
The only wire I'm using is the black ground from the HU itself. The HU has a 16 gauge ground cable that I've butt-connected to a 14 gauge wire that runs to the grounded distribution block.
I'm using distribution blocks for my power and ground. I have a 4 gauge running to each distribution block, and 8 gauges running from the blocks.
OK, so I unplugged the amp and the hiss did go down a little bit, but it's still there. I'd say it's about half as audible then when the HU is plugged into the amp.
I also turned off the gain when I had the HU's rca cables unplugged and still had the slight hissing. Again, I can definitely tell more of the hiss comes from the HU than the amp itself.
So more than likely the HU eh? I guess what I should do is go down to the local stereo shop and have them plug in a few units to see if it's any better?
I just checked the spec for the amp you listed in the amps forum and I was not really impressed by the 70dB signal to noise ratio referenced to 1 watt.
You should set the gain to 0 and check the power input voltage to stay above 12.5V as well as the turn on signal to stay around the same.
Also some component speakers let you in the crossover attenuate the signal to the tweeters, if those have it set it to minimum.
I do have little adjusters on the component crossovers, and they are set to 0db.
I'm not really sure what the signal to noise ratio means.
Regarding the power input voltage - Do I just get a voltmeter to check that? Is there something I can buy as some sort of a regulator to keep the voltage up on that amp? The signal adjustment is on my amp, or the regulator that I'd install?
You can get a multimeter for $10 or so, is not necessary to buy anything else just take some measurements to make sure.
Say you input a clean signal to the amp and you get as output the amplified signal + noise, SNR is ratio between the power ratio between the signal and the noise.
Lastly you can try to set the crossover below 0 dB if it has that setting to reduce the hiss.