best preamp ever - cost is no object

At least this way is more fun - but really nobody is gaining any insight from these kinds of questions & responses.

I seem to recall posting on this thread earlier, but if I didn’t: defining what is meant by ’best’ is a good place to start. There are a lot of aspects about a preamp- gain, noise, distortion, number of inputs, balanced or single-ended, what kind of coupling caps are used and so on.


I’m of the opinion that tube preamps sound better on account of the fact that tubes tend to not sound as bright. So the ’best’ preamp might be a tube preamp. Certainly bandwidth is important, to this end 200KHz is a good minimum on the high side so as to insure no phase shift components in the audio band. On the low side, 2Hz is the maximum low frequency, on the same account, so the preamp can play 20Hz without phase shift.


The preamp should be able to play at levels considerably higher than any amplifier will ever ask of it. This is just common sense, as this practice minimizes distortion and permits the preamp to convey the dynamic properties of the recording itself.


I think that balanced operation is a good idea, since if balanced lines are set up properly, they have less sonic footprint in the system, and less opportunity for ground loops (if you don’t get obvious hum and buzz from a ground loop, it might yet be interfering with the background noise). Its helpful in this regard that the balanced circuit support the balanced line standard, also known as AES48, since these benefits accrue directly from that standard! Otherwise you might have a balanced circuit that is still cable-sensitive.


I’ve found that by direct-coupling the output of the preamp, you can bypass colorations caused by the output coupling capacitor or output transformer. This is because any preamp is expected to drive a solid state amp, so if it has an output coupling cap (or a pair of them if its a balanced preamp) they have to be large enough to allow the preamp to play bass while driving that solid state amp. Despite the construction of the coupling cap, the larger the value, the more inductance is in the cap, and the more coloration as a result. By direct-coupling you get around all that- and obviously you can play bass better. But the mids and highs will be more transparent as well.


Volume controls can be built a variety of ways. The best controls have exotic materials for contacts as they are usually a multi-position switch built up from fixed resistors, which are often also exotic in nature. Care must be taken by the designer to prevent the control from interacting with the devices following it (for example a gain stage) due to something called Miller Effect, which can create a high frequency rolloff in the line stage.


Phono cartridges are a balanced source. So it makes sense to operate them in the balanced domain, since the artifact of the tonearm cable can be minimized in that fashion, and that is arguably the most important place to do that if you play vinyl. So the best phono section might be balanced.


Further, it turns out that the inductance of the cartridge and the capacitance of the tonearm cable set up an electrical resonance that can mess with many phono sections, causing ticks and pops that aren’t even on the LP surface, due to overload caused by that resonance (which can be a 30dB peak)! If the designer didn’t have this in mind when designing the phono preamp, you may have to load the input (cartridge loading) to kill the ticks and pops. The loading can cause the cartridge cantilever to be less supple- and this in turn can affect its mechanical resonance in the tonearm, affecting its tracking ability. Obviously its important for the preamp designer to deal with this issue, as it results in better sound from the phono section!


If the preamp is fully differential from input to output, it will have the ability to reject noise common to both of its inputs (inverted and non-inverted) and also the ability to reject noise in its power supplies. I would expect to see an outboard power supply so as to keep power transformers and the like from inducing noise into the preamp section due to proximity.


So if you want the best preamp these are some things to look at.

Here we go again- zombie thread come to eat your brains!

21 entries and more than 21 candidates! I bet there are more than that. So here's my recommendation:

1. Go with tubes.

2. A good preamp can drive interconnects over 25 feet with no ill effects at all.

3. Avoid remote control volume systems except those where a motor drives the volume control, which will be based on a multiposition switch. All other volume controls fall short!

4. The preamp will be built with a custom wire and if not handwired, then will sport custom materials in the circuit board (not FR4 IOW).

5. It will have the very best caps and the very best caps are Teflon.

6. The signal path will be simple.

7. The outboard power supply will be heavily regulated.

These 7 features are essential! This should help you rule out some of the non-players.

There is also the idea that in pursuit of the 'best' (IOW the state-of-the-art) that the designer must sort out what it is that allows for foot-tapping *and* good specs!

But then at the same time there is the issue of taste. I found out about 25 years ago a disturbing discovery: If God made a preamp and sold it to humans who did not know the preamp was in fact perfect, some would say it was bright, others would call it dull, bloated, bass shy/boomy etc. IOW some would buy it and others would disdain it.

What is left seems to fall in the realm of 'looking good' and 'not looking bad' in the eyes of our fellow audiophiles, after the equipment has passed muster to our own ears.

IOW all the above is meaningless- in such a world, as a designer or as an audiophile you simply have to play the game all out and do the best you can.

The problem here is that the audio industry in general has been lying for a very long time- decades. If a manufacturer, dealer or distributor's lips are moving, he's lying. Seems like everyone says they have the 'best' and the English language being what it is there can only be one 'best'.

The result is everybody is so used to this that they have to take the stuff home and actually see if it works for them. The problem then is that you can't listen to everything, and quite often two people who have radically different experiences and equipment use exactly the same language to describe some pretty different phenomena.

In this context there can be no best- only bedlam.

If you narrow the field, it becomes possible to make some distinctions. For example, I am safe even though I say it myself, in saying that the MP-1 is the best tube preamp at driving long interconnects. There are solid state preamps that can do the same thing, but in the long interconnect department in the tube world there are very few players.

So if might be that if this thread is to go anywhere and be useful, that we create the distinctions that are important, like the long cable example- like, who is the best at working with low output moving coil without step-up devices? I would make a distinction between tube and transistor so that there will be two answers, since we likely will not solve the tube /transistor debate in this thread...

Carlos269, one of the things that all tube equipment manufacturers face nowadays is that tube quality is nowhere near what it was 30-50 years ago! The EH tubes in the Einstein are a good example- nicely packaged but the tubes are microphonic, noisy if not hand-picked and prone to grid contamination in short order.

In the old days the tube manufacturers made plenty of spares; often they offer significantly better performance for not a lot of extra money. The problems one faces with this are several- the really top performers have a cult price, often the tubes are used when advertised as NOS, and certainly finding significant quantities of any type is tricky at best, which is why OEMs use the current manufactured tubes.

It is also true that NOS tubes may not perform as well- as in the case of 12AT7s, there are no NOS types as quiet as the new Chinese any longer as the quiet ones have been used up. Even so, NOS 12AT7s do sound smoother and more robust.

That said, I agree that setup and the technology itself plays a huge role. I think it is true to say that you and Fcrowder are both correct.

Carlos269, having serviced out a few Cellos in the past I was amazed at the poor parts quality. Yes, they are junk, nicely packaged and nicely built. With a price tag to throw you off.

FWIW using a variety of NOS tubes to tailor sound is not merely tone controls- if that were the case we'd have solved the issue years ago :) NOS tubes also sound different because they have different distortion characteristics. Some of those distortion characters are easily heard- just as they are in solid state devices (that are supposed to be low distortion). NOS tube are not used because they sound 'brighter' or 'darker' alone, it is also because they may sound smoother or more detailed. When you can show a "tone control" circuit that can increase detail and smoothness and noise floor *without* changing tonality you will have a marketplace, trust me.

You might compare the use of NOS tubes to fine wines and their differences. The analogy is weak but the complexities of a good wine do have something in common with the finer traits of a good tube.

In these brief few paragraphs I have not really given proper due to what the tube rolling thing is all about- and in my own system/designs I avoid using them at all, as I am interested in improving the design without the variable of the tubes, so I always use the same tube types (once having sorted which ones appear to sound right). So while I acknowledge that tube rolling can make quite a difference, at the same time the technologies that the tubes are operating in make, in my mind, a bigger difference.

It may not be that in their expression that anyone posting here has satisfied your 'scientific process', but my experience has been that most audiophiles that are at all serious are surprisingly scientific- I don't think any of them are doing it by trial and error! If you could modify the character of a tube on the fly, this would be a lot easier. But you can't so you may want to change tubes if you want to get the last drop of performance.

Hi Carlos, indeed I've seen a lot of studio-intended tube devices that take advantage of variable saturation and the like. I've also seen a lot of studio equipment in general- while studio gear in general is often built to a higher level physical construction standard (Studor for example), the component quality in the very best studio gear still sucks. I've rebuilt many pieces with nothing more than improved parts quality and gotten serious improvement without any other modification.

So I do not hold to the idea that studio equipment has *anything* over properly built high end audio gear. In fact, high end audio gear routinely shows the flaws inherent in even the state of the art in studio gear. IMO, engineers designing recording gear could take a hint from high end audio: more tubes, more use of superior materials such as wire, better coupling caps, resistors and so on. I'm afraid that the semi-pro market has eroded a lot of the expectations of studio equipment performance (also IMO) but regardless its a fact that the industry could be turning out dramatically better recordings if they could get the same sort of mind set that high end audiophiles have.

The funny thing is that in the old days (50s) they certainly had that mind set, although back in those days component and materials production was in an embryonic state. Somewhere along the way the recording industry lost it, IMO.