Hello. I am sure I've read this topic allthrough, yet did not see, what is the gain of this amp?
(I meant voltage gain, because I totally believe it is a gainerrr in it's own way).
(I meant voltage gain, because I totally believe it is a gainerrr in it's own way).
entire gain being in autoformer , smidge bellow 4V/V, which is 12db
meaning - rough calculus - for 25W of power, which is 14V14rms, amd needs to be driven with 3V53rms
counting that most modern sources are having 2Vrms out, preamp of 6db (2V/V) should suffice
meaning - rough calculus - for 25W of power, which is 14V14rms, amd needs to be driven with 3V53rms
counting that most modern sources are having 2Vrms out, preamp of 6db (2V/V) should suffice
Ok, thanks for answer. I think I might replace the input stage with vacuum tube gain stage then. Will consider this nice project.
Twitchie, since you kissed me awake, here's what my old fingers came up with that good old Soul...
Just by looking at it it seems clear to me that I must improve the spacing—turn the Cap-Bank 90° (space is just snuggly ok), shorten bottom-plate and rewire the beast. (Ah, and I intend to insert a sort of handle to the psi, to be able to one-handedly lift it out of the chassis)
Since I must remove the boards to replace a faulty part, I will take the opportunity and turn the Beguns 180° (and add the forgotten heatshrink-tubes), so that the wires are parallel from board to beast...
@ZenMod: 🚙
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That's great to see the Old Soul is getting exercise! Look forward to seeing more as it progresses and how much you like it! 
Just a word of caution:
Guess what: The cap-bank was still under load, causing a frightening zap-sparkle! Aah, I sometimes hate to be such a ... greenhorn.
Q 1: do the caps suffer when they're not getting drained for so long? (not speaking of shorting them, mind you)
Q2: Since they're off-board and not connected to anything anymore, how should I drain them?
Ok, so after what, 6 weeks, I got back in screw(-around)-mode, and dismantled my Old Soul to get the weaknesses and mistakes out.
Guess what: The cap-bank was still under load, causing a frightening zap-sparkle! Aah, I sometimes hate to be such a ... greenhorn.
Q 1: do the caps suffer when they're not getting drained for so long? (not speaking of shorting them, mind you)
Q2: Since they're off-board and not connected to anything anymore, how should I drain them?
they are happy being full, waiting to zapp! whatever comes first
use 1K small resistor for few secs of draining, then use 10-20-50R resistor, whatever you have handy
if you go that way, in two steps , no need to use fat ones - small 0207 are good enough
hope you didn't sparkle on channel boards .......
use 1K small resistor for few secs of draining, then use 10-20-50R resistor, whatever you have handy
if you go that way, in two steps , no need to use fat ones - small 0207 are good enough
hope you didn't sparkle on channel boards .......
Thanks, ZM!
No, luckily, the cap banks already were off-board—shorted with a scale ("massstab")... and even luckilier, the zap didn't go through both hands, phew!
shorting works even if the boards are floating/unconnected?
No, luckily, the cap banks already were off-board—shorted with a scale ("massstab")... and even luckilier, the zap didn't go through both hands, phew!
shorting works even if the boards are floating/unconnected?
shorting/discharging caps - simple as connecting resistor between rail(s) and GND
same as you mounting bleeders
which I'm never doing
lazy
irresponsible
stupid
same as you mounting bleeders
which I'm never doing
lazy
irresponsible
stupid
Redrum… 
excuse my ignorance, but, although I believe you that it bleeds the caps, I don’t understand it. Or, is the remaining energy just consumed by heating up the bleeders?
excuse my ignorance, but, although I believe you that it bleeds the caps, I don’t understand it. Or, is the remaining energy just consumed by heating up the bleeders?
Thank you! I like bad. OTOH, I am simply stating that I have some experience in controlled discharge. However, keeping in mind that out of control discharge might be more fun, at least in the short term.
I simply think that being a family man, myleftear perhaps unconciously zapped his PSU in search of a spontaneous one.
Took apart the psu, prepped the wires and immediately got caught by the „what-wire-should-I-use“-monster 👹
Went with oversized somethings, just because.
Went with oversized somethings, just because.
^^ correct
someone's replacement IRF9510 are in PO, sent
oh boy, what adventure Post Office is these days .......
someone's replacement IRF9510 are in PO, sent
oh boy, what adventure Post Office is these days .......
Haven't had much time to play lately but getting another look at Old Soul - I didn't order parts kit so I ordered my own parts. Does the grade for the optocoupler OK101 and OK102 (PC817C) make a difference? I notice now there are B, C and D grades/bins with different transfer ratio (Max) as well as forward DC current differences (10mA for B, 50mA for C&D). I checked my DK order and I have B&D grade parts, no C. On the channel I have working, it's fine at 1W but just past 2W, it starts to distort rapidly. Please note this is the working channel. I haven't checked the channel that doesn't bias yet.