At the Burning Amp meeting, the replacement parts for the now discontinued Toshiba parts were offered. The light is not entirely extinguished, when considering seriously making a Blowtorch preamp, or equivalent design, in future.
Good morning John. I hope that the Burning Amp event went well for you. So are these Toshiba devices a one to one reproduction of the original Toshiba devices or are they just "close" to the same?
Can somebody please list the recommended cross-reference parts? I doubt I'll build anything like that soon, but it'd be handy to know them.
LSK/LSJ + usual Toshiba number. BTW, I asked samples, they promised to send, but shipped nothing.
Thanks Pavel. I was hoping someone would say they announced an equivalent dual for 2sj109. I suppose we're still talking about lsk170/lsj74 matched, right?
QUESTION: I've been searching quite a bit part one of this thread (thousand+ pages), but haven't been very successful. Does anyone have handy a pointer to a reasonable schematic that resembles (functionally at least) the BT preamp? I'd like to do a bit of analysis on it, for fun.
QUESTION: I've been searching quite a bit part one of this thread (thousand+ pages), but haven't been very successful. Does anyone have handy a pointer to a reasonable schematic that resembles (functionally at least) the BT preamp? I'd like to do a bit of analysis on it, for fun.
http://www.diyaudio.com/forums/soli...rch-preamplifier-part-ii-147.html#post1930881
Have fun (if analyzing this <insert your attribute here> anywhere resembles fun)!
I 'sampled' Linear Systems with J73's and K146's, yesterday. I said: "Measure them and weep." As they still have a little bit to go, before they truly replace Toshiba.
re: regulators, etc.
since it sounded like this might fill a need,
just wanted to pass on a link to some good reading material for the less experienced folks:
(don't be put off by the paper's title)
http://www.darksmile.net/ee/Superimposing_Low-Phase-Noise_Low-Drift_Instrumentation_Techniques_On_RF_Design.pdf
if you're in a hurry, start at page 3.
enjoy ... 🙂
mlloyd1
since it sounded like this might fill a need,
just wanted to pass on a link to some good reading material for the less experienced folks:
(don't be put off by the paper's title)
http://www.darksmile.net/ee/Superimposing_Low-Phase-Noise_Low-Drift_Instrumentation_Techniques_On_RF_Design.pdf
if you're in a hurry, start at page 3.
enjoy ... 🙂
mlloyd1
It should be pointed out that this RF design article attends to many of the factors that we attempt to address in high quality audio designs. The only significant difference is that in audio, we don't always have to worry about minor DC drift in power supplies as much, because audio is not a DC signal.
By its very nature, it is virtually impossible to pick up and transmit DC signals to the ear. Neither the microphones, nor the loudspeakers will do it.
However, everything else seems to make a difference to some degree or another, just like it does in this RF design article.
By its very nature, it is virtually impossible to pick up and transmit DC signals to the ear. Neither the microphones, nor the loudspeakers will do it.
However, everything else seems to make a difference to some degree or another, just like it does in this RF design article.
Hi John,
It's a shame that you are disappointed in the Linear Systems complementary JFET parts. Can you elaborate on what aspects of the parts fall short?
What measurements did you make? Did you put them into an existing preamp and listen to them? Or did you do both?
Thanks,
Bob
I'm curious myself. K146/J73 is supposed to be better than K389/J109 (about twice the transconductance and about the same noise).
Linear Systems has given me devices to evaluate, from time to time. They still have some 1/f noise problems, on occasion. Still, they are our greatest hope for the future. The 2SK146 and the 2SJ73, are quieter than the 170 devices, but what is really important, they can set a standard that they can shoot for, for 1/f noise. At least, that was my point.
How bad can they be? Is that critical for BT? BT is not a phono preamp and I already proved in this thread that the BT noise performance is set by the output MOSFETs rather than the input JFETs.
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