[ntrl]

Hi All!

I construction preamp for poweramp (with tone compensation, bass and volume control, sources selector).
And I had a question. What gain necessary for a modern preamplifier? 2.0? Or less or more? Sound sources will be - sound card EMU1212 and dvd a player.
What timbre control better: active or passive? (imho. for active control easier find necessary caps).

Thanx.

 

[adolphe]

For preamp gain, I believe most have between 6dB 12dB. I can't really help you on the timbre control. In some ways it would likely be easier to go active, but I think a simple and more elegant method would be passive if you can get away with it for your needs.

-Scott

 

[Garbz]

Ntrl this depends on some math and your amp situation. Modern amps have 50db of gain I think or thereabouts, but more important is the absolute max input voltage of the amp's input stage. The gain of the preamp should be such that the input signal should produce an output signal that will not clip the input stage. This is all a bit complicated.

The method I rather use is plug the poweramp in, grab your quietest CD (classical music usually) put it in the player and then tweak you music so that it is comfortable to listen to at about 85% This gives you a little more boost if you ever feel like loud music and will allow you to use the maximum rotation of your volume control.

This applies to digital volume controls too. Set the -6dB -9 or -12dB point to this quiet CD and you will have the largest range of volume to select from.

In the end as long as it is not to quiet, or you do not overload the input stage of the amp the actual gain of the preamp is will not make a difference.

 

[ppl]

Most Preamps have a gain of 11 or about 20dB this is to acomidate the output of the Mag Phono Section these put out about 800 mV while a CD player will output about 2 volts so in effect you can get by with no preamp with Modern sources in theroy however since recordings are never loud enough to output the full 2 volts from the CD player a gain of 11 is still a valid concept YMMV