Demonstrating my ignorance concerning 'gain'

and the role of a preamp.

My faint understanding of gain is that it is an increase (or gain, of course) of a certain voltage expressed in decibels relative to some arbitrary voltage level.

Now, without needing to get into great detail, if the source outputs 2 to 5 volts, and without a gain stage at all is able to drive the output amplifiers to thunderous levels, then what use is gain?

In fact, in this case, isn't gain counterproductive? In that the user of a gain producing preamplifier has less control over the resulting volume of the speakers?

I would almost thing that 'unity' gain or even 'negative' gain would be desireable, in that given the first case, no amplification of the signal is required, with it's attendant changes to the signal, and the second case, like 'reducing' an image greater clarity is perceived (maybe not true but perception).

So why am I obsessing? I have a CD player with variable output levels and have it plugged directly into my amps. When I listen to music I almost lose control of my voluntary musculature, it sounds so good. Nonetheless, could I be missing something?

 

The argument most audiophiles will give you against connecting your variable gain CD outputs directly to your amplifier is that these controls are usually of poor quality compared to those found in a preamp. Of course, I've never been able to figure out how running a single cable from a CD player to an amp could sound worse than a pair of cables and another circuit.

The other factors to consider would be, of course, related to impedance mismatches.

 

Sound like those questions I used to read in the audio magazines years ago when discussing amplifier design.

Figure this out, design an amp, and make lots of money!

I honestly don't have an answer for you, but you are not alone in your questions, and certainly not the first!

Steve may be on to something. Cable impedence and it's reaction with related componants has much to do with the final sound. I would also look at the power supply.

Where am I going?

 

If you just have one line-level source (say a SACD player) then you will most likely have plenty of gain and you won't need a preamp. You could just have a pair of interconnects with built-in attenuators - Ric Schultz of EVS has built and sold exactly that. Wouldn't suit the couch potatoes.

If you are interested in having no preamp you need to investigate if your system will work like this. Arthur Salvatore on his web site www.high-endaudio.com explains how one can safely use a track like Bolero, with it's very low-level beginning, to test if your system has enough gain with the CDP connected DIRECTLY to the amplifiers.

If the opening of Bolero works for you (it's loud enough), an attenuator may be all you need. The so-called "passive preamp".

Arthur Salvatore believes that if you do not need a line stage, you will get the best sound without one. Well, that's just someone's opinion, but he has been around the block and you should at least read what he says.

I could not live without remote control of the volume/mono/polarity now that I have had these functions for a year or so. There is a passive preamp - the Audio Synthesis from the UK - that has remote control; and so this device actually plugs in to a wall-wart. Expensive though.

There is something infinitely sexy about a preamp, and so we love them. But do we really need them?

Regards,
Geoff

 

Well according to Steve himself when I asked the same question about running your CD/SACD player directly to your amp. the answer was a definate no!"You loose the musicality that your pre-amp offers". "The best way is to use your pre-amp is to have the CDP volume cranked to max. if you only have variable output, if not just use the standard outputs for the best sound possible".

 

Well, in my case, I'm running my CDP directly into my tube amp (a Decware Zen) with very good results. But of course the Zen was designed for this sort of setup, has a "volume" control built in, and works best with a 2 v. CDP output signal. I do miss having a remote volume control though!

Ray

 

I find this all pretty interesting since I've heretofore been very happy with my passive. Not that I'm not happy with it any more, but there is an active preamp on order just the same. There's only one way to really find out what's what.