2. amps-preamps
  3. 1329159366

Preamp function.

Hello everyone. I have always wondered what a preamplifier does. I am currently investigating valve amplification for the first time. one of the options i am also considering is a valve preamplifier to add to a pass labs power amp. i am also considering all valve. Transistor or valve, what does the preamp actually do, apart from switching and volume control. As an experiment i added a musical fidelity a3cr that is from my second sytem, to my pass xa30.5. the results were very positive and an improvement over cd player direct. i am aware the musical fidelity a3cr is not in the league of the pass, but it certainly improved the sound. Most noticeably was a quieter back ground and better musical presentation. From this i gather that a preamplifer does add something to the sound. i had always believed it purely carries the signal unaltered. If anyone here with technical kwowledge mind throwing some light on the subject, i would appreciate it( others might find it interesting too). i have read reviews where writers describe the sound of the preamp. i had believed they were actually describing the sound of the player and amplifier and the ability of the pre to carry the signal unaltered? Thank you.
james123

Showing 1 response by elizabeth

elizabeth
6,726 posts
 
It is in the history of the stuff.
A preamp used to be a full featured device.
Preamps had all sorts of things in them.
They would have TONE CONTROLS. and the user would be able to adjust the sound a bit to compensate for various issues with them. then the preamp also always had a phono section. Since a phono cartridge needs a lot of extra amplification, and RIAA equalization.
Finally most preamps also had sets of in/out to supply taping functionality.

Then along came CD around 1983 or so.
One of the oddities of CD players was the huge increase of output from the player. All components used to output about a quarter to one half volt signal to the preamp. No more... The Cd player output TWO volts. So a big discrepancy from all other sources and CD/DVD

Gradually the phono section was dropped from a lot of preamplifiers. The Phono box became a separate device...
Also the Audiophile revolution of the 1980s (really the prices just went crazy, and "Audiophilia" was born..IMO)
Anyway the tone controls also disappeared.
So then all that is left is the volume balance, and selector, and tape functions

So the preamplifier has LOST most of it's functions.
And a lot of folks just go straight from the Cd player or DAC to the amp.
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