class d digital amp

[Torquative]

hey all, just wondering if anyone can help

On the weekend I brought a Jaycar Response 5 channel class d digital amp. I figured it sounded good, digital audio, 4 channels and a sub channel! Suits me perfactly.

Problem is plugged in I get some hiss/hum noise, yeh ok, Ive since found digital amps do that and it gets drowned out with the music.

But even more so is the issue that 3 of my 5 preset radio stations have static, one of which is quite bad. I plugged in my old xplod amp tonight and the static goes away, connect the response and its back?

Does anyone have any ideas or suggestions as to how to get my radio stations back? Unfortunately the box was destroyed so I cant return it. If not then I might have to consider using it as an overpriced monoblock as the bass through the sub is incredible, its just the static through the radio stations that kills the experience!

[holdenboy]

Firstly, how are the RCAs ran? i.e. along the passenger side with the speaker cables or with the power cable?

What type of RCAs are they?

The Response digital amps have been known to have interference...but not as bad as your describing.....hows the noise when playing a CD etc?

You should still be able to take it back and claim warranty, so long as you still have the receipt.

[StoneX]

It's not digital, it's "class D". The "D" does not refer to digital.

Since it causes the problem and the Sony doesn't, that's good enough reason to take it back to the store and explain it's making excessive noise.

[Torquative]

ive just realised its possible that the antenna is getting interfearance from the power cable as I ran the power down the LHS of the car and the RCAs down the RHS of the car.

[holdenboy]

Maybe, but if thats the case i would imagine the Sony amp would do the same. Unless youve ran the antenna cable and power cable side by side for a while (50cm or more) then it MAY have an effect, but i dont think this is the case.

So i take it the interference goes away when playing CDs then?

[Torquative]

yeh, what happens is the old amp worked fine, but I wanted to upgrade because I wanted to have only one unit bolted to the car because of things like track days etc where the car is exposed to some fairly decent g-forces. Plus I need the boot space.

So I ran new RCAs down the drivers side where the old RCAs were to replace them as they were low quality.

Hooked it all up, ran a CD, played with bass, yeh good. Plugged in the Ipod, (running a standard head unit modified by Phreddy with the RCA/Ipod mod), yeh great, excellent clear bass and audio, very impressed.

We noticed a bit of a hiss or hum at low volumes, so we threw the RCAs down the middle of the car. Still no difference, although when they got close to things like the SRS sensor or when we grounded one end of the cable and not the other it affected the noise. when I unplug the rear RCAs from the head unit it goes away. Phreddy has suggested perhaps a ground loop has been created as its common, plus ive read on this type of amp thats normal operation anyway.

But the issue is on tuesday morning I went to listen to the radio on the drive to work and found static on the stations. One of the stations has a weaker signal as its not a local one, but I never really had an issue with it. Used to get some shh shh shhhhhh static every now and then but thats to be expected. Instead all I could hear was shhhhhhhh static.

Ive since played with it, grounding the RCAs at one end affected it, moving the antenna cable away from the amp power cable that sits behind the glovebox also affected it so i now have 4 of the 5 stations working with the 5th being listenable but still staticy.

Ive been told a few different theories which Im yet to try due to lack of time

- upgrade the power cables. I didnt realise Im only running 4 guage, perhaps 8 guage will help as the amp may be struggling for power and/or not grounding properly

- run the RCAs down the passenger side and power down the drivers side, (reverse to what they are now) which puts the RCAs away from interfearance from the electronic accelerator pedal module and from interfearing with the antenna cable. I also think the fuel guage sender wiring runs down the drivers side, but I could be wrong (I look at too many cars to remember my own sometimes)

- install one of those ground loop eliminator thingos because it sounds like when I plug the rear RCAs in im creating a ground loop

Stone, I didnt realise its not "digital" I was under the impression it was, but Im an idiot when it comes to car audio. This is the baby Jaycar Electronics

Im determined to get it working because I cannot return is as I dont have any packaging therefore its not in a re-saleable state. I asked if they gave me a new one could I use that box to return this one in and it sort of confused them, although if worse comes to worse I'll re-try it with the boss to see what happens, although I'd love to see this thing working as its a perfect size for where its mounted and theres only one opposed to an amp and mono

[holdenboy]

Yep alot of those theories are possible.

Although i would imagine changine your power cable probably wont make a difference to interference. By the way if your using 4AWG cable the next upgrade would be 2AWG or 0AWG. 4AWG should be sufficent for that amp anyways....probably worth trying a new earthing point too, not to mention sanding the area back to bare metal before attaching the terminal. Using the underside of the parcel shelf isnt a good idea either, they are usually spot welding and dont provide a good earthing point. The wheel arch is ideal but better yet is one of the chassis rails.

If you can, try another head-unit, it may be the earth tracks inside the unit itself that have been damaged....it isnt a Pioneer unit by any chance?

edit; maybe not the headunit as most of the problems caused by this effect all sources, not just the radio. Just out of curiosity, do you have a power antenna, and if so where did you get your remote power from for the amp?

[bezz]

Didnt the early versions fo the jaycar class d amps have some noise troubles? Give jaycar a call and see if it is an issue with em - you never know they might replace it for you..

[padrickz88]

seriously take it back to jaycar i took my speakers back with no packaging and no receipt, he didnt want to but they stuffed up and all i had to say was "well its not like i could of brought it from anywhere else? who else sells this brand?"
also told him i have recommended people to go to his store in the past and he changed them over for me

so maybe just give that a shot?

[Torquative]

the head unit is acctually a stock standard VZ Blaupunkt head unit thats been modified by ASR (Phreddy) to have RCA's out. havent had an issue with the old amp either

Remote wire comes from the modified head unit

No, grounding isnt on the parcel shelf. Its run to the ski port seat mounting point against the body shell of the car

Yes power antenna, as standard with VZ

no, no problems with CD or Ipod (ipod being another Preddy modification) only radio stations

I'll try a few things on the weekend, if it doesnt work i'll take it back.

[holdenboy]

It could be to do with the remote power coming from the same wire as the power antenna wire.....long, long shot i know but its worth a try.

Remove the unit and try connecting the remote wire for the amp to an accessories output, maybe the cig. lighter or some other source not associated with the stereo. Even if you just run a small wire from the positive terminal of the amp and into the REM terminal, yes the amp will be on all the time but you can just test it and see if the interference goes away on radio.

[Torquative]

hmm thanks for the suggestion. Its currently disconnected completely because Ive had enough of putting up with it until im on holidays next week, but I'll also give that a shot!