Tube Pre-amp BAT, ARC, EAR, Sonic Frontiers

Snarkonmars, If you are looking for balanced tube preamps, I would think your short list would look a little different. Am I missing something?

Snarkonmars, I don't think SF ever made a balanced preamp, although they have the connections. At least I say that in the context of being fully balanced throughout, like our preamps are.

What is the advantage of fully balanced preamp then?

Balanced (hopefully differential as well) circuits have the advantage of increased power supply noise rejection and often a considerable ability to reject hum when directly subjected to hum fields from a power transformer. Differential circuits also have the advantage of a theoretical 6 db/stage of gain less noise. Over the entire preamp this itself can be quite an advantage.

In practice, the actual noise advantage over single-ended is usually a little less than 6 db, but not by much if the circuit is designed correctly. If you give it the benefit of the doubt and say, 4 db, and if you were to have 3 stages of gain in the preamp, the noise advantage would still be at least 12db, which is significant.

If, on knowing this is the case, one were to design a balanced preamp that took advantage of this fact, it would be possible to build a preamp with less gain stages. That would be a simpler signal path- less places for the signal to get messed up.

Not everyone knows this, but phono cartridges are inherently balanced (if you've ever wondered why phono systems are the only single-ended source that needs that extra ground wire, its because its a balanced source that is being used single-ended). So it is possible to have the signal go from the MC phono cartridge to the output of the preamp, be balanced all the way and only encounter three gain stages.

A balanced preamp can accept balanced inputs. Balanced interconnect cables (if built correctly) will inherently sound better than single ended cables as a number of cable issues are reduced by going balanced. Finally, the output of the preamp, if it really supports the balanced standard, will be able to drive cables 100 feet long without degradation. This means that you can put the front end of the system where you want it, rather that being constrained by a short cable requirement. It also means that the interconnect cable between the preamp and amplifier will not be dictating the sound of the system.

So- for audiophiles anyway, the advantages are profound.

Snarkonmars, what I meant was that some products have an XLR connection when the internal circuitry is single-ended. There is no advantage to the connector; the advantage lies in the topography.

BTW any balanced preamp will convert a single-ended signal to balanced without issue or degradation, as part of the normal operation of the preamp. We've not been providing single-ended connections for the most part (although we have always had 2 single-ended line inputs) in an effort to convince the user to hook things up right and get the most out of the preamp as a result (I'm sure that's why BAT has does it that way too). That's why we've always had a balanced input for the phono (in fact we were the first to offer that feature), as it is a balanced source anyway.