Voltage and impedance

[a6laze 0]

Portable setup: iPod 5.5g/Panasonic SL-CT720 PDCP both via lineout >> Xtra x-1 >> Etymotic er-4p

 

Hi people! I'm new here and this is my first post.

I've read about equipment matching and synergy and therefore would appreciate knowing the following:

 

1. Output impedances & voltages of the line outs of the ipod 5.5g and the pannie sl-ct720 pdcp

2. Input and output impedances and the voltage output of the Xtra x-1

 

Also, am I right to say that between the source and amp the aim is voltage transfer, thus, the input impedance of the amp should ideally be 10 or more times the output impedance of the source (bridging), while between the amp and cans the aim is current transfer where the goal is to provide sufficient energy to drive the transducers, and therefore the output impedance of the amp should ideally be matching with the impedance of the cans?

 

Thanks heaps.

[pegasus21 0]

The part about the input impedance of the amp is almost right. The ideal impedance should be infinite. In practice, this is usually in the order of KOhms or MOhms. Output impedances are usually around 10 Ohms.

 

The part about the amp giving enough current is right assuming you have sufficient voltage to power the transducers. The voltage would be heard in terms of volume.

 

Impedance matching is mostly for maximum power transfer which isn't so critical for sounding good. Basically just means more efficient and thus less power wasted. Although there are some amps that require a certain range of headphone impedance to sound good. Usually people buffer the output so as to prevent that from happening.

Edited December 18, 2006 by pegasus21

[mrhobbit 0]

not sure whether this is relavent but........

 

the amount of "power" that an MP3 can provide to the headphones to drive it, does it vary GREATLY??? and if it does, does a smaller player neccesarily correspond to less power?

 

sorry ah i not very sure what the tersm are, abit of a technical idiot

[a6laze 0]

 

The part about the amp giving enough current is right assuming you have sufficient voltage to power the transducers. The voltage would be heard in terms of volume.

 

 

Thanks for taking time.

 

Ok, so for the amp to provide enough current, the impedance of the amp out should be as low as possible?

Actually, I'm a little confused. For high impedance cans, they require more voltage and less current and vice versa for low impedance cans. So, for high-Z cans, they need very little current from the amp out but more voltage, so for them the impedance of amp out should be low also because p=u(squared)/i ?