In the spirit of ZM's suggestion I have been doing the following for the last couple of years. I directly tap the output of the DAC. The signal is on two legs, each riding on DC (equal but opposite polarity between the two legs). This is sent to step up transformer (2:1 voltage gain and reflecting 4:1 decreased impedance). The transformer also has the added bonus of stripping off the DC.
This is led to the pot and B1 buffer (of course). You probably want to increase the pot from the recommended 25k to 50k so the load on the source/DAC (reflected through the transformer) is high. You may need to slap a RC LPF as a reconstruction filter (although the transformer itself may provide some filtering)
You can go crazy choosing a transformer. My inexpensive solutions (in the USA) are Edcor WSM series (about $10-15) or Cinemag (15 series for about $60 or a bifilar for about half that). Jensen has a series 11 model that should also be a candidate but at a higher cost.
Buffers and transformers are fun to play with (as ZM has reminded us).
This is led to the pot and B1 buffer (of course). You probably want to increase the pot from the recommended 25k to 50k so the load on the source/DAC (reflected through the transformer) is high. You may need to slap a RC LPF as a reconstruction filter (although the transformer itself may provide some filtering)
You can go crazy choosing a transformer. My inexpensive solutions (in the USA) are Edcor WSM series (about $10-15) or Cinemag (15 series for about $60 or a bifilar for about half that). Jensen has a series 11 model that should also be a candidate but at a higher cost.
Buffers and transformers are fun to play with (as ZM has reminded us).
Diamond Alternates
Curious here on this idea. I'm kinda trying to proto up some alternate buffers for a M2 and a F6 front end and curious to see if there's any new boiled water in Zen Mod...
tnx boyz ...... as I said , I'm in age when I certainly forgot more than I know now ....
regarding buffer type - I'm working on Diamond buffer , which is going to have similar THD spectra as complementary JFet one , and even better when loaded hard
of course that most important advantage is 100% lesser number of preciousssssss JFets in it
I couldn't s...we'll see soon , I'm getting pcbs in few days , will test them as Iron
Curious here on this idea. I'm kinda trying to proto up some alternate buffers for a M2 and a F6 front end and curious to see if there's any new boiled water in Zen Mod...
ZM since we are on the topic of buffers and transformers
a)do you feel that even a simple buffer like the one above sounds best when supplied with a shunt regulator?
b)do you feel that a transformer or an active sounds better when doing a SE to differential conversion?
Thanks. nash
a) absolutely . others are having different fetishes , I'm having just shunt regs.
and thin wire
and (all ) speakers
and tubes
and transformers
and ......
b) it really depends of several factors , but good xformer when properly fed and properly loaded , is hard to beat in signal energy preservation department.
however , there are electronic solution for that (se to bal) task , but I can vouch only for solutions where two output phases are intrinsically connected , contrary to often used OP based circuits , where existing phase is just flipped with OP and voila ...... you have both legs , but for me they're as from different persons
nothing wrong with Frankenstein , but he's not audio signal
ref to your post #31 - you don't need paralleled JFets with that iteration of buffer
what I meant with paralleling is to do that with buffer made of 2SK170 up and 2SK170 down , to achieve same Rout as with complementary type
regarding shunt reg - note that one JFet vertical pair ( whichever sex it is ) is drawing no more than Idss current , which is 6-12mA for BL range
so , practically any shunt reg round is capable to feed that
say that 50mA is good point for that , feeding one channel
everything above that is waste , both of heat and my time for typing
edit : I believe I'll have Good Gemini and Iron Pumpkin as kit in time of 1.5 months , with several possible iterations - basically SE or balanced , where balanced is (believe it or not ) SUSY , through xformer unique intrinsic characteristics
what I meant with paralleling is to do that with buffer made of 2SK170 up and 2SK170 down , to achieve same Rout as with complementary type
regarding shunt reg - note that one JFet vertical pair ( whichever sex it is ) is drawing no more than Idss current , which is 6-12mA for BL range
so , practically any shunt reg round is capable to feed that
say that 50mA is good point for that , feeding one channel
everything above that is waste , both of heat and my time for typing
edit : I believe I'll have Good Gemini and Iron Pumpkin as kit in time of 1.5 months , with several possible iterations - basically SE or balanced , where balanced is (believe it or not ) SUSY , through xformer unique intrinsic characteristics
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