2. amps-preamps
  3. 188876-140796

Preamp - what's the purpose?

Intentionally dumb question...

I've heard various 5-15W tube amps in my room. EL84, 300B, etc. They all have input stages and the output stage. I send them a line-level signal from a DAC.

Sitting a few meters away from my loudspeakers, the first watt alone gives me roughly 80db of volume. I think these amps are biased to expect the line level signal directly. Why wouldn't the designer do that?

So what's the point of adding a pre-amp? Why do people do it?

thanks in advance

 

clustrocasual
erhardaudio's avatar
erhardaudio
6 posts
 

@heartwoodcorp

glad to hear that you are enjoying your Aretha!

troutstreamnm
45 posts
 

Many preamps have subwoofer circuitry with high pass filters and gain control too. The switching ability, volume control, remote control and multiple analog and digital inputs/outputs are very important to me.  The pleasure of a tube preamp allows for a different dimension in sound quality too.  

arnold_h
96 posts
 

That’s the thing these days, most dac sources have subwoofer circuitry with high pass filters and gain control.  My Oppo 205 has all these features plus many more including surround 7.1. I run it direct to my power amp through balanced XLR connection.

carlsbad2's avatar
carlsbad2
1,602 posts
 

Some people have multiple sources and need a switch.  I have 2 inputs but have an amp with 2 inputs.  My new amp I ordered custom has 3 inputs, one for a spare.  

Some DACs don't have volume control, so they use the pre for that.

Some people think a preamp improves the quality of the sound.  I say it can only color it.  

And I do it just like you--DAC into my tube amp.  

Jerry

chenry's avatar
chenry
184 posts
 

Fair question. Obviously, you need a preamp if your amp has no volume control and you want to use more than one source and want to conveniently select between them with a switch. With some sources, you might need amplification to get to line level. Phono, for vinyl and MC or MM cartridges and no phono preamp, some digital sources (I remember an Apple Airport I used as a streamer some years ago needing quite a bit of volume addition from my Rotel Receiver.) If you want to use headphones but don't want to have a dedicated headphone amp, a preamp can provide. These days, other devices have assumed some of the preamp functions, so you could make do without a separate preamp. Many streamers have DACs and preamp volume, bass, treble and balance functions of classic preamps in their phone apps, some even have phono preamps and headphone amps with headphone jacks, functions which duplicate or replace those typically on a preamp. Depending on your use case, the need for a preamp could range from not at all to essential.

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