Tube pre-amps: what defines "better"

Did your friends give you a reason why you should add a tube preamp to your system? Are you running all solid state right now? A passive preamp? What IS your system now? Is there something you don't like about it, that prompted them to suggest a tube preamp? What kind of music do you listen to and how do you like it presented?

Because of my personal preferences, right now the only type of preamp I'd want is a tubed version. I enjoy their naturalness, expansiveness, and smooth, sweet nature. I've had success mating them to solid state amps for a bit of both worlds.

Good luck.

different tube pres will have different sounds, ranging from extremely warm/tube-y/euphonic to clinical and almost solid-state - you need to determine which sound works best for 1.your ears and 2.your system.

if you have a turntable, phono sections differ enormously - with some pres, they're great, with others you'd want to get a separate phono pre

Musicslug is right about different tubes having their own character. I'm pretty familiar with two types, the 6SN7 and 6922 families which my preamp and DAC use respectively.

In general, the 6SN7 will have a fatter midrange and upper bass which yields a lightly more organic sound than the 6922, 6DJ8, 7308 family which on the whole is more neutral sounding. I like both!

When considering tube preamps, pay attention to the tubes being used in its design.

Generally speaking, the more a tubed preamp costs, the better the power supply. More often than not, the preamps' performance will depend more on the power supply and voltage regulation than the types of tubes it uses. Regulating voltage and providing clean power is costly in terms of components used and construction. This pretty much applies to all active audio components.

Real world example: a friend purchased a used Melos tubed preamp for around 700. I purchased a used Audible Illusions Modulus 3A for 1200. We plugged both of them into a aystem with very good speakers and a custom interstage coupled 300b SET (best we've heard and that includes Kondo). Our findings when we took the Melos out and inserted the Modulus 3A; the midrange suddenly had detail and transparancey again. The bass was tighter. The Melos has already been inspected and pronounced in fine working order; the Modulus has its stock tubes from 4 years ago and they s/b changed out.

The only tubed preamps I was considerign in the used market when I finally bought the Audible Illusions Modulus 3A (mostly because it was available and the other two are next to impossible to find used):

Audible Illusions 3A
Audio Research SP9
VTL Ultimate (first on the list, hardest to find)
CAT SL1 Signature or one of the other SL1 models in phono. This one is significantly more expensive than the others.

The Audio Research preamps (SP6, 8, 9) are excellent units but, at their age, certainly should be put on a bench and gone through as parts probably require replacing and/or upgrading. I'd budget an additional 500 max for this task once the unit is acquired.

The Modulus 3A is a great unit but uses up tubes a bit quicker than others. A good set of upgraded NOS Siemens EC88 (6922) tubes is about 100/ea and you need 4 I think; have not installed mine yet.

My finding was that there are not that many options in the 1000 to 1500 range for a quality used high end tube preamp if one insists on a tubed phono section.

If you have patience I'd counsel wait for a VTL Ultimate.