Noob speaker input question

[FP]

I understand how a waveform works but I have a question about preouts and inputs.

If I plug my headphones into my iPod the iPod is supplying them with power to drive.

If I plug my iPod into my receiver via 2 RCA (L/R) jacks the iPod is still presumably sending the same power to the RCA inputs right? What does the receiver do with the little bit of power the iPod is sending?

Now on to my main question. If I plug my iPod into my car stereo and crank the iPod volume up to 100% and use the radio to manage volume I get significant clipping. If I set the iPod's volume to 50% and pump the radio up louder I don't get any clipping. Can someone explain why this is so?

If I want to use my iPod with my receiver would it be better to crank the iPod or crank the receiver?

 

[spidey07]

You're clipping the pre-out of the ipod. This can have a lot to do with input impedance.

As far as the receiver, same thing.

Depends on input impedance and sensitivity (voltage). What you normally want to do is run the pre-amp (ipod in this case...sorta) as high as it will go without clipping. It is possible to clip pre-amp output and you commonly hear it with car stereos.

 

[FP]

Hmm... So are you saying that the iPod would clip when at 100% regardless of the output path (headphones, car stereo, receiver)?

 

[spidey07]

The ipod can clip depending on the input impedance of the device it is attached to.

 

[FP]

Originally posted by: spidey07
The ipod can clip depending on the input impedance of the device it is attached to.

Can you go into more detail on how the impedance of the device can cause it (an amp) to clip? What has a higher impedance, some cheapo iPod headphones or a car stereo (when attached to an iPod).

 

[Modelworks]

Headphones vary in impedance , usually anywhere from 32ohms to 600ohms.
Thats what the ipod jack is designed for by default.

http://sound.westhost.com/amp-basics.htm


A simpler way of explaining it is that the signal coming out of your ipod is already amplified.
The car amp has an input stage that is expecting a signal at a given range. Say from 1-2 volts.
the car amp then takes that, amplifies it again and outputs it to the speakers.

The car amp doesn't care what you set the volume control to on the radio.
If what you are putting into it is too much voltage then it clips or distorts the input stage, and that noise gets amplified instead of what it would have sounded like at a lower volume.

An analogy might be someone talking to you in a room at normal volume.
You can hear them well, then repeat out a window to someone else what you were told.
If someone in the room were to shout in your ear at close range , you would only repeat out the window that you heard noise.

If you turn your ipod too loud it will distort the input stage of the receiver and you will get noise, so its best to set the ipod to a volume that sounds the clearest and use the receiver for the volume control.

 

[FP]

Originally posted by: Modelworks
Headphones vary in impedance , usually anywhere from 32ohms to 600ohms.
Thats what the ipod jack is designed for by default.

http://sound.westhost.com/amp-basics.htm


A simpler way of explaining it is that the signal coming out of your ipod is already amplified.
The car amp has an input stage that is expecting a signal at a given range. Say from 1-2 volts.
the car amp then takes that, amplifies it again and outputs it to the speakers.

The car amp doesn't care what you set the volume control to on the radio.
If what you are putting into it is too much voltage then it clips or distorts the input stage, and that noise gets amplified instead of what it would have sounded like at a lower volume.

An analogy might be someone talking to you in a room at normal volume.
You can hear them well, then repeat out a window to someone else what you were told.
If someone in the room were to shout in your ear at close range , you would only repeat out the window that you heard noise.

If you turn your ipod too loud it will distort the input stage of the receiver and you will get noise, so its best to set the ipod to a volume that sounds the clearest and use the receiver for the volume control.

Excellent description. Thank you.