Why use a pre amplifier

[whiterx]

I have been looking on the internet, and most people say to use a pre amplifier. I am just wondering what is the purpose? why do you need a pre amplifier if your amp has a volume control?

I can understand for input switching, but what other reasons are there?

cheers

Tom

[Coherent]

The main reasons are
Input switching
Tone controls
Balance controls

[rrrremus]

A few reasons for using a pre-amp:

1. Separation from the high voltages, high temperatures and magnetic fields present in a power amplifier.
2. RIAA Phono amp
3. Flexibility for bi-amping. I have my pre-amp feeding the crossovers and then the two power amps.
4. Because of the extra space available in the pre-amp housing i mounted a USB + TOSLink DAC board right into my preamp.
5. Sometimes the line-out output swing of a CD player for example is of about 1 Volt Peak to Peak. You might loose dynamic or SNR if you do not have an intermediate stage because the input stage in most power amps works at hight voltages ( more than 40 ) and sometimes the 1 volt swing is not enough.

[el156]

Hi !
Because i only use a CD player, and it has an output of 2V , i dont use a Pre amp ,i just dond need it , the main reason for a pre amp is several inputs or a Phono pre amp due to noise reasons. Tone controls are not usable in HIFI i think!
Silvino

[tangmonster]

less is more!!

Don't add preamps if you don't need it!

[meshplate]

Unless you have a specific need for an active pre-amplifier, and rrrremus has listed some of the considerations, then I don’t see any advantage, especially if your volume control is then always turned all the way down.

The only benefit I can see is it may provide a better impedance match between sources and a power amplifier. An active pre has high input impedance and low output impedance, so the relative input and output impedances of the connected equipment and the choice of cables is far less significant. If you do not have a specific requirement for a pre, and you take care with load capacitance the input stage presents, then a simple pot is fine – maybe even better

[McCormack]

I've configured systems both with and without preamps, and to my ears a good (emphasis on the word good) preamp gives a fuller, richer, more dynamic sound to the music.

[analog_sa]

Originally Posted by whiterx

I can understand for input switching, but what other reasons are there?

The only reason i use an active pre is the sound - to my ears better than passive resistive or inductive attenuators. Why better? No idea as i use short interconnects and all my power amps have high input impedance.

Btw, this has been discussed ad infinitum and to start a new thread...

[kevinkr]

Originally Posted by analog_sa

The only reason i use an active pre is the sound - to my ears better than passive resistive or inductive attenuators. Why better? No idea as i use short interconnects and all my power amps have high input impedance.

Btw, this has been discussed ad infinitum and to start a new thread...

Same here..