Audio Experts needed: speakers vs. headphones

[cris nitro]

Good morning all;

In a separate thread, I queried how to hook up headphones/ear buds to the rear speaker plug on my R1200RT. I have that finished and came up with a clean look for the headphone jack located in the cowling around the instruments. I have an IPod in the glove box connected to the bike so I can control the volume and play selection thru the wonder wheel. However, the quality of sound coming out of the headphone jack is not as "full" or "rich" as it would be if the headphones were connected to the IPod directly. I need to max the bass and lower the treble to just to make it barely acceptable. I'm not an expert, but assume that the rear speaker jack I connected to is not made to connect directly to headphones. Just wondering if there is some type of adapter or amplifier I need to put between the speaker plug and the headphone jack.

 

Thanks for listening, pun intended.

Cris

[Hammer610]

Hey Cris!

I can only venture a few guesses here since I am not exactly sure of how the system is wired up. So I need to pose a few questions to figure out where the possible issue lies.

1) how is the sound quality with another sound source such as the radio? This would indicate a problem with your iPod interface.

2) does your iPod sound ok through the speakers? If it sounds ok with the speakers this would indicate a wiring issue to your headphones.

3) have you tried a different set of headphones? Start with the volume all the way down and bring it up slowly to avoid overloading your headphones.

 

Typically a headphone jack is taken directly from your amp output thru resistors then to the headphone jack. The resistors are used to drop the power down to a level that won't overdrive the headphones.

Additionally double check your wiring. Tip and sleeve are right and left positive connections. The sleeve is the negative wiring connection. NOTE: I did not say ground. Mounting the speaker jack to chassis ground may cause issues. The sleeve and the portion of the jack are electrically the same point. However, the negative (-) speaker connection and chassis ground should not be connected together.

I spent the early years of my electronics career rebuilding amplifiers and working on audio systems. In fact I currently own my own sound company and still build and repair my equipment. I've seen many symptoms of grounding issues.

I hope I was able to give you a primer in tracking down the issue.

If you need further assistance send me a PM and I will send you my phone number and we can talk in greater detail.

 

Regards,

Chris

 

[cris nitro]

Thanks Chris. Wow, that is one mean looking avatar you got there.

 

1. Sound quality of speakers using either radio or IPod is good.

3. I'll try a different set of head phones tonite.

 

My buddy also told me I would have better quality if I went directly to the amp output, but that would mean pulling the radio out, which I wasn't up to.

 

Another buddy who is pretty knowledgeable, thinks it is a impedance issue as the head phone jack is connected to a speaker output and I am driving head phones. One thing is that the BMW adapter plug that is plugged into the rear speaker plug, has 4 wires, one left, one right, and one ground/common. The 4th wire is not used. I am wondering if the 4th wire should also be connected to the head phone jack ground. Basically tie the two grounds(if the 4th wire is a ground/common) to the headphone jack.

BTW; I bought the head phone jack from MCM electronics and it only has three leads on the back, ground, left and right.

 

Cris

[Hammer610]

Yeah it is nasty .... That was this years birthday present.

 

Could you send me a schematic of what you have? You don't have to go directly to the amp. Connecting at the speaker side is perfectly ok. Just remember the negative wires going to your speakers are not going to the chassis ground of your motorcycle. Most stereos share the same negative point for both channels. But they don't use chassis ground. Is the jack mounted to any metal? Or is it mounted on plastic? Typically most headphones are of high impedance. So I would add a 10k ohm resistor in line with the tip and ring terminals coming from your speaker wires. Also, are your headphones mounted inside a helmet? If so try a regular pair and see if the sound quality gets better. It could be just a proximity issue.

Oh one last thing. Is the sound quality good when using the radio?

Good luck!

[Hammer610]

Found this. Hopefully this helps. Use their resistor values... My guesstimate value was way off.

http://sound.westhost.com/project100.htm

 

They used a switch to switch between speakers and headphones. You can purchase a switching Jack that will do this automatically when you plug headphones in.

[cris nitro]

Thanks, Chris. I will look into it.