2. amps-preamps
  3. 1206138848

Experts: Why is preamp important?

I know that's a naive question, but the real question is how important a preamp upgrade is relative to the rest of a system. I've heard the statement "a preamp owns the signal", but I don't know what that really means in terms of ultimate sound. For example, is preamp to amp like a transport to a dac, whereby most people would contend that a great dac with a cheap transport can still sound great? I've upgraded my front speakers in a HT system to B&W n803s/HTM1. I currently use a 130wpc Pioneer VSX49tx HT receiver. Obviously I can get better sound from better amplification, and I'm considering a separate integrated amp for the fronts. But the question is can I still make a great improvement using the pioneer's pre-outs to a much better amplifier? Where should I really spend my money? Thanks much. This forum has been tremendously helpful, and I'm sure this thread will do the same.
jeffkad

Showing 4 responses by atmasphere

atmasphere's avatar
atmasphere
11,575 posts
 
preamp functions:

1) provide volume control
2) input switching
3) provide any needed gain or attenuation
4) and least understood- control the interconnect cable between amp and preamp to minimize the effect of the cable. Most sources cannot do this BTW.
atmasphere's avatar
atmasphere
11,575 posts
 
Don_s, If a preamp has a low output impedance, many of the differences you are accustomed to hearing in interconnect cables go away.

In fact the balanced line system used for decades in the recording studio and broadcast was conceived to eliminate (quite successfully) interconnect cable interactions.

Many sources do not have particularly low output impedances. For that reason it is useful to have a preamp line stage to buffer those impedances from the interconnect cable. This prevents the cable to the amp from having any significant effect on the sound.

Quite a few preamp manufacturers do not recognize this function of preamps, so there are many preamps out there wherein the interconnect cable between the amp and preamp is quite audible. So if you hear big effects between interconnect cables between the preamp and amp, then your preamp does not support this function.
atmasphere's avatar
atmasphere
11,575 posts
 
Pinkus, in fact our preamps are designed to support the balanced line standard- in effect dramatically reducing the effect of the interconnect cable to the point that it is no longer important. This is not to say that you can't hear differences, but they cease to be the make-or-break sort of thing that you hear of so commonly. The reviewers are not wrong- they are simply not working with preamps that attend to this issue.

Honest1, the answer to your question is 'yes'. For that reason, you want to keep the length between the sources and the preamp inputs as short as possible. Anytime the source or preamp cannot control the cable, you will want to keep the cable as short as possible to reduce interaction. It won't eliminate it but it will help.
atmasphere's avatar
atmasphere
11,575 posts
 
Tomcy6, for termination of a balanced line 600 ohms is the standard. By preamp standards, this is a very low impedance and many preamps can't drive that without a loss of bass, loss of signal level or both. Even though the termination is often not used, its a good idea to be able to drive it so as to be able to control the interconnect cable.
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