Autocom questions

[MLRickards]

Never wait until a Friday night to test out a new farkle! If it doesn't work perfectly...no way to talk to the manufacturer for two long days

Oh well...figure I'll get better answers/advice here. I've searched the forum and have found all the threads on Autocom issues, but as usual I can't find one that addresses my specific issues.

I have the Super Pro AVi unit with the following hooked up:

Motorola Razr - aux 1
Digital Voice Recorder - isolated lead in aux 2
iPod and XM radio - isolated lead in aux 3
Valentine One and Quest 2 gps - isolated lead in aux 4

Issue #1: Significant engine whine without any of the audio devices hooked up. I have it grounded to the battery and powered from the quartet harness.

Issue #2: When I do hook up the audio devices I get all kinds of interference noise. I'm using what seems like every isolated lead known to man, or at least that Autocom sells. I think the interference is mostly from #1 above, though.

Thoughts on what would cause the basic ground loop type whine with my set up?

Thanks!

 

[Byron]

Have you tried running power directly from a fused line from the battery? Will be interested in your outcome because my unit is on its way and I may experience the same issue.

 

[MLRickards]

I wanted to avoid that because there's no on/off switch for the unit, so wiring direct to the battery would require adding a relay to the switched source to keep it from being on all the time. Not the most difficult thing in the world to do...but hoping I won't have to.

After posting my original note, I took the bike out for a quick ride using ear buds instead of the helmet speakers. For some reason, the whine wasn't as noticeable (I guess the volume of the music was louder), but it was still there and for what I paid for this damn thing...not acceptable

The sound sure is fantastic, though! I love that part of it.

 

[Rob Hephner]

The Autocom has ZERO isolation between the audio ground and the unit ground, therefore if you ad any audio device that uses a ground from the bike you will get noise.

You must isolate the power supply of the Autocom with a filter or an isolated power supply. Do a search on my name and Autocom and you will find a devive from Navone Engineering that I have suggested several times.

 

[MLRickards]

Thanks, Rob. What was strange to me was that I'm getting the engine whine with none of the audio devices hooked up. Just the plain Autocom and the headset or ear speakers. The only ground involved there is the Autocom itself, right? (I'm an electrical dweeb so sorry for the dumb questions)

 

[Rob Hephner]

Yea, that is possible because they also use shielded cables which work backwards from the way that they think they should. In reality when you shield a cable for a mobile produuct you actually create an inductive loop which can pick up noise.

If you move the cables around you can resolve that problem.

I realize that this seems pricey http://www.autosound2000.com/filters.html but if you use it you will have no noise issues even with their cables.

 

[MLRickards]

Thanks, Rob. I'll try moving the cables around first. Don't mind the cost of the doo-hickey you referenced as much as I dread having to completely re-wire everything! I was so pleased to have it all "neatly" hooked up to the quartet harness--and in several cases I trimmed the wires to fit just right.

But, good to know that there's a fool-proof option out there.

Thanks again!

 

[Rob Hephner]

No problem, it would be nice if Autocom spent the $20 in parts to isolate their power supply in the first place!

Sure, it would add $50 to the cost of the unit, but heck the thing is supposed to be used on a vehicle, right?

 

[MLRickards]

Okay...here's another question. If I got the isolated power supply and hooked up just the Autocom to it...would that solve the problem? Or would having the accessories connected through the quartet harness still introduce interference?

Also, is the isolated power supply in a "constant on" mode? If so, would you have to add a relay to the set up to keep the Autocom from being on all the time?

Sorry for the "twenty questions", but you've triggered the student in me and I want to learn!

 

[Rob Hephner]

Yes, one isolated power supply providing power to the Autocom unit will cover you for anything else added. (Other things like radar detectors, sat radio and other items just get power and ground like normal.)

The power supply will stay on as long as it has power, so if you want it to turn on and off with the bike switch you need to wire it that way. You can simply choose the appropriate wire from the quartet harness. It provide power to the Autocom so you will only have a 3amp draw max, you do not need to combine the power needed for the supply and the Autocom in this type of arraingement.

 

[sparkinator]

Issue #1: Significant engine whine without any of the audio devices hooked up. I have it grounded to the battery and powered from the quartet harness.

Thanks!

I've got one on the way also and have been reading up on 'em. Read somewhere that grounding to the battery will pick up alternator whine. They recommended a ground to the frame somewhere close to the unit. FWIW.

 

[Rob Hephner]

Sparky,

The unit does not have isolation. I have one and have tested it.
The only way to have no noise is to isolate.

The battery is the worst place to ground, that is true. But if you add other audio devices, regardless of where they are grounded, you will get noise.

 

[sparkinator]

Thanks, Rob. What was strange to me was that I'm getting the engine whine with none of the audio devices hooked up. Just the plain Autocom and the headset or ear speakers. The only ground involved there is the Autocom itself, right? (I'm an electrical dweeb so sorry for the dumb questions)

No arguing with that Rob, but grounding the unit to the frame is cheap and easy. And you don't have to wait on parts.

 

[birdie_xx]

I've had the Pro M1 and the Super Pro AVI units powered from the bike, directly from the battery and never had any issues.
This is on the XX, which shouldn't matter.

I can hear a bit of a "hiss" when I plug my cell phone to the charger and when I'm on the phone. Other than that I can hear just the music.

Cheers,

 

[bcst1300]

All of your Audio equipment should be powered and grounded as close to the battery as possible. A power filter for ignition noise can help too. all audio wiring should avoid proximity to any part of the ignition system or the alternator. The area behind the frame and close to the airbox is a relatively quiet place. Shielded leads can help with only 1 end of the shield grounded. For a power lead that would be a positive, negative, and a shield too.
The honda quartet harness is not a good place to get Audio power but is a good place to power the relays for audio devices.

 

[MLRickards]

I've had the Pro M1 and the Super Pro AVI units powered from the bike, directly from the battery and never had any issues.

Birdie,

When you powered your Autocom directly from the battery, how did you handle making sure the unit was off when the bike was off? Relay?

 

[Rob Hephner]

Birdie,

Your phone audio is isolated, which is why you have no issue.

As far as grounding to the battery, I have explained this in depth before, it is the WRONG place to ground. I am the one that posted the frame ground as a solution to noise when using a audio device alone before, do a search and you will find it.

Shielding is HORRIBLE for automotive audio use, once again a search will give you the complete details on that.

The Honda Quartet harness is a perfectly good place to get power.

Look, there is no magic here, it is perfectly understandable science. If the ground is not isolated you get noise, if it is (and with enough isolation to rise about the noise floor) you don't. Grounding to the battery puts you at the return path for charging and directly connected to the AC noise you are trying to avoid.

A metal shield creates a magnetic loop and draws in the very noise you are trying to avoid, so UTP is a much better way to go. Since the Autocom unit has special made cables you are stuck with them and therefore why I suggest the Navone piece to help you avoid all of those issues.

This all comes from a solid understanding of the design of mobile electronics and 20 plus years of practical installation experience.

 

[Rob Hephner]

No arguing with that Rob, but grounding the unit to the frame is cheap and easy. And you don't have to wait on parts.

Sparky, you are dead right and if you never going to hook another audio device up to the Autocom it is the way to go!

Also the way to go if just an audio device is powered from the bike. (Sat radio and the such.)

 

[birdie_xx]

When you powered your Autocom directly from the battery, how did you handle making sure the unit was off when the bike was off? Relay?

I pull the plug.....

I use the quick disconnect power cord and both units (one at the time) sit in the tankbag. I run the power cord different now, but the photo shows how I do it....

Birdie,

Your phone audio is isolated, which is why you have no issue.

Rob, I said I've had no issues at all and the power cord runs straight from the battery. And I'm talking about speach and music.
Again, when I'm on the phone and the phone is charging, I hear very little background noise. But this is the only time....

I love my Autocoms !

Cheers,

 

[bcst1300]

I don't think I have read so much contrary advice to my experience both in class and in the field. Rob i searched your posts and have not found any background on your reasons not to derive your ground from the battery. For the record I only have 2 terminals on the battery for positive or negative. 1 wire is for the OEM ground and 1 for the Oem +12v I have added a fuse block controled by relay and an accessory ground block served by a #6 and mounted on the frame which is a parallel path both +12 and grounds are short as practicable. Dispite my advice about shielding I have not chosen to shield my wiring on my St but did on the Yamaha I had previously. The bigest mistake most people make with shields is terminating them on the supply and load ends thus creating a ground loop.
Battery supplied accessories like MP3 players or cell phones are immune from ground loops because they are isolated as you have pointed out. Radios like CB's are very prone to ground loops as are any bike powered audio accessories. The first best practice for audio is to source both the +12 and grounds from the same place and as close to the battery as practicable. If your experience says on the other side of the alternator connection? fine as every wire has some voltage drop and I can see that even a few inches of wire can add some isolation. The quartet harness is not the optimal place to source audio power. It is a messy and noisy souce but if all your audio sources and accessories get their power from the same place then you will mitigate this noise source a little.
The first time I bike powered my Autocom and Cb I used a fuse off the auxilliary for the Autocom and was using the Quartet via the glove box 12 volt outlet. I installed filters in each line and had horrible alternator noise. By moving the CB power source to the fuse block I got rid of the alternator whine. I have removed 1 of the filters as well. I added a Garmin GPS that was also powered for a while from the quartet and there was the whine again. move the +12 volts to the fuse block and the whine is gone.
As for the shielding satement I can't see how a correctly installed shield would or could pick up noise or create Magnetic loop? Correctly installed shielding reduces magneticly induced signals. That is the reason we use stp in electrically noisy environments. UTP is often enough but if electrical noise is an issue shielding will usually be superior.
I too am iminently qualified to give opinions on electrical installations. Not saying your experience is wrong but I have been studying and practicing and teaching electrical and electronic theory, repair and installations since the mid 70's. I have electronic, radio, electrical, high voltage (over 750 volts), low voltage, control, scada, network, construction, audio, fire alarm, security, power generation, telecom, network etc. experience and a couple of car stereos installed in those 30 years so I can piss pretty high up the wall too.