Switchable Hi-Z input impedance, how ? - Page 41 - diyAudio
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Old 1st November 2012, 08:12 AM   #401
juma is offline juma  Germany
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Voltage doubler is OK (since power consumption of the gain stage is very small, couple of mA max) but gain stage has very small PSRR so it's recommended to use the clean PS.
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Old 1st November 2012, 09:25 AM   #402
tinitus is offline tinitus  Europe
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I decided to focus less on scrap from now on
since this is beginning to look better I will buy two small print board trafos
one 2x 12V, and one 24V( or another 2x12V)
up to 5VA they don't cost much
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Old 8th November 2012, 07:15 PM   #403
tinitus is offline tinitus  Europe
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picking up the pieces
this have taken a slightly different turn, and I decided that the original box will be a stereo preamp, with two optional outputs
2 channels tube output, and another 2 channels balanced output with BA-3
might need this later for planned tube amp project

since its now a balanced BA-3 I need more space
cut a small piece off the previous tube 'board', and turned it 90 degr
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Old 9th November 2012, 01:34 PM   #404
tinitus is offline tinitus  Europe
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possible layout for the 2 channel SE-balanced output with BA-3

because its to some extend is exposed to radiated heat from the tubes Im trying make it even for all parts of the curcuit, and hopefully not have too much drift
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Old 10th November 2012, 09:22 AM   #405
tinitus is offline tinitus  Europe
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and the instrument high-Z input, low pass/high pass with EQ, a tour'de'france, the full route
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Old 13th November 2012, 08:37 PM   #406
tinitus is offline tinitus  Europe
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I might do another box
the height is better suited for any possible tube experiments
need a frontplate

and was lucky to get a Salas custom designed +30V reg
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Old 14th November 2012, 08:04 AM   #407
tinitus is offline tinitus  Europe
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nicely vented lid, but where is the rest
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Old 14th November 2012, 12:46 PM   #408
shanx is offline shanx  Canada
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Hi Tinitus,
Nice to see your continuing development. I have been checking your updates. Just thought I should send a quick post, I didn't have much to add to previous progress. Looks like you are pretty close to final for the Fet preamp.
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Old 16th November 2012, 11:13 AM   #409
tinitus is offline tinitus  Europe
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I have a small C-core trafo I hope will work
the regulated +/-12V from the 2x 24V, +30V from one 0-28V
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Old 28th November 2012, 11:52 AM   #410
tinitus is offline tinitus  Europe
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when ordering parts for my Salas reflektor I found theres a higher voltage LM317HV
will start out with that one, until I get the more complicated reflektor done
thats from the 28Vac down to +30Vdc

and I might also use 2x LM317HV as pre regs for 2x TO92 regs, to get the 2x 24Vac down to the +/12V I also need
the TO92 will be with the buffer

but man this is looking 'costly'
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