What are preamps for ... ?

[kermit_xc]

Sorry for the trivial question ... but I really don't fully understand the principle of a preamplifier.

thanks

-- kermit_xc

 

[j_garcia]

Signal management and volume control is the preamp's fundamental job in HT. It does no processing or amplification, thus the "pre"-amp.

 

[Seth=L]

Preamplifiers are in all receivers. You may hear people refer to a receiver as an amplifier, but what a receiver really is, it's a combination of a preamplifier, tuner, and an amplifier. When you are using a surround sound receiver you still have the same parts, preamplifier, tuner and an amplifier, you just add a processor into the mix.

Preamplifier- Adjusts volume and switches components.

Amplifier- Amplifies line level output to usable levels for powering a speaker system

Tuner- This makes a receiver a receiver. Without the tuner it is called an integrated amplifier (sometimes Pre-Main amplifier), unless it is a surround sound receiver though I have never seen a surround sound receiver that doesn't have a tuner. Integrated refers to the integration of a power amplifier and preamplifier.

Processor- Processes digital audio whether it be Dolby Digital, DTS, PCM, or some other digital audio format.

Hope that answers all and any questions you may have.

 

[kermit_xc]

thank you very much ... indeed, very well explained

 

[skizzerflake]

In addition, pre-amps usually handle the signal if you have a turntable. That signal is very small and needs to be boosted before it goes to a power amp. In addition, there is a specific "RIAA" equalization curve that is applied because records are cut with bass frequencies at a low level in order to increase playing time and make life easier for the cartridge stylus.

Bass, treble and balance controls are applied at the pre-amp stage too

 

[Seth=L]

Too right you are.

 

[Ampdog]

Good explanations.

I could only add why (and where) the "borders" occur:

The term originated in the Tube era. One did whatever necessary processing (filters, equalising of records, tone and volume controls) in the early stages as said, followed by a power amplifier. The latter usually had a stage or so of further amplification, phase inverter and power stages, all included in a global negative feedback (NFB) loop, within which one does not control.

Since the amplifiers were heavy while controls were required on a (convenient) front panel, it was natural to find a physical "break" between the two, leaving a light box with controls for fitting onto a cabinet's front pasnel while the heavier power amplifier(s) were left in an out-of-sight place on the floor.

The relative masses totally changed with time and advent of transistor amplifiers, but the destinction sort of stayed. There is no particular merit in integrated/separates except for physical convenience.

 

[no. 5]

There is no particular merit in integrated/separates except for physical convenience.

what about in multi-channel?

 

[Gilgamesh]

What are the advantages of an external preamp then?

 

[robot]

Separating the more 'delicate' electronics from the big transformers and magnetic fields and whatnot may reduce the electrical noise introduced to the signal. Also, the more high end amps are pretty big, might as well put them in two separate boxes. The more boxes you have the better your system is.

Back in the day there was no such thing as a reciever. Sometime (maybe in the 60's or 70's?) people started putting amplifiers, tuners, and preamplifiers in the same box, probably because it was cheaper.

 

[GreenJelly]

Many "Pre-Amps" are infact a Pre-Amp with some of the additional features listed above (Like a Tuner, Processor, etc). Some Pre-Amps dont handle volume control, and leaves that up to the amplifier... If these are infact Pre-Amps or fall under some other name, they are almost always refered to as Pre-Amps.

I like the idea of having seperate Amp and Pre-Amp. That allows you to upgrade your system as new Tech comes out, without having to upgrade your Amp. Unfortunately these systems are expensive.