The future of preamps

@ Atmasphere, Thankyou, I am glad you told me that a tube pre-amp needs a coupling capacitor at the out-put to protect against DC, that was helpful info, cheers.

Audiolabyrinth, I think I need to clarify that. I think there are maybe 3-4 tube preamps with direct-coupled outputs (Berning made a hybrid called the TF-10 years ago, there was the Messenger and we make two of them. Pretty sure Krell was not talking about us... I think we would have heard about that.

Anyway, the rest of the tube preamps made have either an output coupling cap or they have an output transformer. Either way they won't be making any DC! That is actually a greater danger with a solid state preamp, although most of those have output coupling caps too.

Ahhh, yes, I 'tis remember well when, lo those many years ago, 'ol Steven Stone, reviewing still for Stereophile, told us all that passive pre's would soon take over the earth, that active pre's were not, um, "transparent" enough and that, impliedly, 'ol Ken Shindo should just then pack it up...

Jeez, can one hear an echo around here?

I know, this is hardly dispositive in an empiric sense, but I know of a guy who streams only digital into class D amps - talks a lot, doesn't listen much, cognitively chatters like a monkey - and who says that his is the most "transparent" way, it just has to be, its so, um, logical.

My response? You can't describe the color purple to a blind man...

@ Atmasphere, Hi, If your preamp M-1 is direct coupled, what do you use to safe guard from DC exsposure if I attempted to use your product with the krell 700cx?

Audiolabyrinth, it uses a servo that corrects the DC. The servo also lets you know if there is a problem it can't correct. Its simple, and very reliable.

The actual circuit does not want to make large amounts of DC in the first place so the servo only has to make small changes. We have a patent on how this is done. There are several advantages- part of the reliability comes from the fact that the circuit can't put out large amounts of DC even if it were damaged, so it does not need a protection relay or complicated housekeeping circuits to make it work. Its reliability comes directly from its simplicity.