I'm beginning a project for which I believe the Janus PS. would be the best choice.
Part of the project is a circuit consisting of 2 x 6922/6dj8 tubes, meant to serve as a buffer.
1:1 (unity) gain.
It needs + and - 12 to 30 VDC, or so says the propaganda from the maker... and 12 VDC for the filiment.
Consensus of subjective (listening) opinion says that around 12v just isn't enough for the 6922/6dj8 and the result is "vague" "bloated" type sound.
That makes sense to me, as those tubes were intended for much greater voltage.
The higher end of that range seems better..
That is where I would be very greatful for your advice and knowledge!
I'm in a bit over my head here...
I read through the postings regarding operating points and parameters, etc...
I understood what they were "getting at" but it would take me a week to work through the formulae to come up with a result...
Also, experience counts for a lot!
I'm assuming that the overall limit is set by the current limit of the LM regulators?
Still, I'd like to use the highest allowable voltages.
The Janus would seem an ideal choice for this purpose.
I would prefer to provide a seperate 12V supply for the filiments.
Here I'll provide the supplied schematic and photos of the board.
Well, I would if I could upload attachments...
Here is a url for it meanwhile.
I would also be greatful for advice on which transformer to get (110V mains), but of course that depends on the above.
Also, it bothers me to have no "soft start", like the other Augustica PS boards do.
Perhaps you feel that at this voltage level its not nescessary?
I should provide some further info on the overall project, to put it in some perspective.
The main purpose is to build a component..... variously called a "line stage" or "control center" or "preamp"..
(though perhaps none are precisely accurate).
I need source switching, as I use several and don't like plugging and unplugging...
Attenuation, of course...
While I can't design a circuit, I know what I like...
I've been involved in audio since the 70s... and have "come to believe in" certain things, for good sound, or at least the
sound I like.
I want to use a TVC (transformer volume controler) for attenuation.
So why not just use a "passive" "preamp"?
Well... several reasons.
My sources vary all over the map.... tube and SS tuners... digital music streamer.. even mobile phone/tablet, and eventually a tube phono stage...
Also, I use long interconnects to the amp(s)...
Amps too..... from a 470k ohm input Dyna ST-70, to vintage and newer SS amps 10-22 or so Kohms... and eventually others that I'd like to experiment with in future....
I've come to believe that impedance mismatches are a core source of problems in audio systems... and responsible for many a bad result.
"System synergy" that people talk about is often a matter of good impedance matching, system-wide... I believe..
I don't need any gain.... or at least very little should it be inevitable.
TVC's seem to do strange, unpredictable things with impedance too...
So, it seems to me, that buffer as the heart of a "preamp" would be a great thing!
Why a tube buffer? Well, mainly because I like "tube sound"
I've heard all the debates.... and nobody will ever talk me out of it.... lol..
Even if its my imagination, I LIKE it... it just seems more like MUSIC to me.... and I find it holds my interest better..
Especially in this day of "dry" sounding digital sources.
Heck, even in the vinyl LP days, mixing/mastering had that effect, especially here in the U.S. where they tailored the sound
for terrible car loudspeakers... Those who cared went out of their way to find British pressings for that reason... often with little luck.
Also, every preamp I've liked best used (at least a couple of) 6922/6dj8's...
That they're voltage devices seems positive too.
So I've had this idea in mind for a few years.... and I'd like to test it out. Succeed or fail (sonically).
A tube buffer "on either side" (at input and output) of a TVC.
I've been describing this as for a one (mono) channel, so of course everything would have to be doubled for 2ch stereo.
If seperate transformers, (and for 12v filiments) were used, it would also be dual-mono.... for a slight/reasonable additional sum.
Your advice, and your boards, would be most appreciated!!!