Are Pre-Amps necessary?

And to all, active preamps have volume controls as well, and most times not as good quality as the better passives pre's usually use. Also active pre's use many other distorting/colouring components in them.

At least passive pre's usually only have a quality pot, which is why they are the closest in sound to going direct (a straight piece of wire) when used correctly.

And balanced is not needed if you only use <3mts interconnect, and in many case better as the balance inputs and outputs on many pieces of equipment, are opamps to make them balanced, when their true circuit is not, so your better off using the single ended inputs on those, again a more direct path, instead of going through opamp etc for balanced

This entire post is false. Many active preamps employ custom multi-position switches rather than pots, built up with fancy resistors to create a volume control. MBL does this, CAT, Atma-Sphere and many others. The first 2 paragraphs thus debunked.

The '<' symbol means 'less than' but I am assuming that in the quote above George meant to use the '>' symbol.

The benefit of balanced operation is there even if the cable is only 6" long. Anyone familiar with motion control can tell you that... the rejection of noise induced in the cable does not matter how long the cable is. It relies on the Common Mode Rejection Ratio at the input of the receiver (amplifier). Most solid state amps made today are actually fully balanced and many of them have differential inputs. Some are executed with opamps, some are not. Opamps can have extremely high CMRR values, in excess of 120dB, and set up with unity gain they offer no coloration whatsoever. There are places where opamps are not a good idea, such as the input of a phono section (where the input circuit can be overloaded quite easily) but as an input to a solid state amp they can work quite well. Opamps made in the 1960s, maybe not so much. The main thing you might encounter is increased noise floor if a cheap opamp is used. But if a nice one is used the circuit will be quiet even on horns.


We've been making fully differential balanced amps and preamps since 1987 and not used any opamps for input or output, just FWIW...


George frequently quotes Nelson Pass, who is one of the top designers in high end audio today. Nelson's designs feature differential inputs without opamps for their balanced operation. His are not the only like that by any means. The last paragraph is debunked; the entire post is rubbish.

It makes sense no pre would be most transparent, resolving, the straight wire concept.

Go back earlier in this thread to see what a straight wire isn't always the most neutral. The problem is that a passive volume control isn't a bit of wire. If it were, it would not have a resistance value.


Math and engineering principles are at play here- when you put a resistance in series with a source impedance which is expected to drive something to the best of its ability, its rarely a good thing. This can cause an audible and measurable loss of bass and impact. Put simply, its an example of a thing that is too simple to to its task properly.


This is not to say that you can't get it to work. To do that you have to be sure that your source has a direct coupled output and is capable of driving the load (the input of the amplifier) properly. And the interconnect cables will have to be kept short, and RCA only (balanced lines can't be executed with a passive volume control and observing the balanced line standard at the same time).

but look how much longer that has taken than anyone thought.

About 40 years so far and still counting... And now tape is back after a long hiatus. And we're already to the point where the industry doesn't want to make CDs anymore. For digital, streaming is rapidly becoming the thing; if you're into digital you might have a CD player, a streamer and a mulit-terrabyte drive with DAC... all with different output impedances.


Even if the LP dies, which I'm thinking might be about ten years (although there are still advances occurring in that field), active line stages seem to have their work cut out for them.


Now if you have a DAC with multiple inputs and a volume control on it, designed to drive an amp directly, the simple fact is you have a line stage with a DAC built in. But like it always works when you integrate things like that, if you want to improve the DAC, you'll be changing the line stage too...

They are not needed these days with nearly all of todays sources, except maybe with weak tube output sources.

Sheesh. It was nice when george was off. Now we have rehash this again and again. Tape is still very much with high end audio as is the LP. These media are not served by any DAC I know of. Plus there are active line stages that have better volume controls than I'm used to seeing in DACs. Line stages first started showing up in the early 1990s when the idea of an all-digital system became a thing. Rather than a relic, it seems as if they are not going away anytime soon.


If you are going to run a passive control, the best place for it is built into the power amplifier. That way the impedances involved can be far better controlled. But if you have monoblocks it gets tricky.


My front end with preamp has 30 feet of interconnect between the amps and the output of the preamp, which also drives a subwoofer amplifier. In this way I keep the front end of the system at a lower level of vibration and I can run a Distributed Bass Array. These are the sort of things you can't do with a passive control. At best, to make those work you have to run short cables- 30 feet is out of the question. If you need dual outputs, you'll instantly be in trouble, and if you want to be finally rid of that pesky standing wave in your room (causing a loss of bass at the listening chair), you'll need a distributed bass array to do it.

Not when many poweramps use opamps as their balanced inputs, and then it routes to their single ended input.
In these cases by using the single ended input, you get a better sound, as there’s no opamp in the signal path then.

OK George, by this comment I have to assume that opamps are not a thing with which you are familiar. Opamps (operational amplifiers) have very high gain open loop. Their gain structure is thus defined by the feedback resistance vs the input resistance. When both values are the same the opamp has unity gain. This is a lot of feedback, and most opamps today can support that amount of feedback such that at any frequency in the audio band they will be entirely neutral.


And unity gain is how such at thing would be set up, since the amplifier in question would have no need of additional gain when using the balanced input. At any rate, if the designer did execute the opamp input in a substandard manner (and I have seen that), such a thing does not reflect on balanced operation nearly so much as it does on that designer!


Take this from someone who made their career in tube electronics, OK?

So the sound quality will be unaffected although I do concede that using an opamp solely for this purpose is a poor execution of the amplifier design; better if the amp simply has differential inputs used for either balanced or single-ended operation (and many in high end do exactly that). McCormick and Pass Labs being two examples off the top of my head...

Sure balanced has it’s place in over 3mt interconnect runs, for noise cancelation only, below that there is no need for it.

This statement is false both audibly and measurably. The benefit of balanced operation is there even if the cable is only six inches long.

IME this always comes down to cables. I used to know this guy named Robert Fulton who, more than anyone else in the world, founded the high end audio cable industry. He had his special RCA cable that sounded better than the average Radio Shack cable at the time. It was a bit of a revelation...

Here we are 43 years later and cables are still a thing. When you run passive controls you are more subject to the coloration of cables. But there was a tech that was developed to eliminate cable colorations. That is the balanced line system, which has a set of standards that have to be met.

Most manufacturers in high end audio ignore those standards. So we have audible differences in balanced cables too- sparking the question of whether balanced line cables are even better at all. If the standards were being met this would not be a question! But to meet them, you'll need an active preamp to drive them. You can't do it properly with any passive volume device made.