thanks guys
gain ?
not sure
right now I use a Creek headphone amp to drive my 2-channel power amp(stereo with Sanken outputs)
as high-Z 'buffer/preamp' in front it I only have a compressor with 12db gain
both are ste at around 12 o'clock', most of the time below, and rarely above
and thats a lot louder than I need
for very 'silent' practice I switch off the 12db gain from compressor
I forgot I also have small EQ on the mid
cheap digital crap thing
cant do without right now
bypassing it gives me very heavy loud low bass
fun sometimes
and matches some types of music
but mostly its a bit too much
hey, I have my proto/test preamp powered up now, +18.6V
gain ?
not sure
right now I use a Creek headphone amp to drive my 2-channel power amp(stereo with Sanken outputs)
as high-Z 'buffer/preamp' in front it I only have a compressor with 12db gain
both are ste at around 12 o'clock', most of the time below, and rarely above
and thats a lot louder than I need
for very 'silent' practice I switch off the 12db gain from compressor
I forgot I also have small EQ on the mid
cheap digital crap thing
cant do without right now
bypassing it gives me very heavy loud low bass
fun sometimes
and matches some types of music
but mostly its a bit too much
hey, I have my proto/test preamp powered up now, +18.6V
what size would you recommend ?
from I have read the bypass cap gives cleaner sound
I guess as a result of more even and controlled gain
on the backside, it should result in more unpleasant 'overdrive', but thats a guitar thing, and not sure I should worry about that
but I will experiment with that, thanks
If you are using a compressor with a 12 dB gain you may not need more gain there. If you were plugging the bass direct-in then you may want about a 6 to 12 dB gain to give a bit more drive to the tone stack and tubes. For bass you would use a larger bypass cap. Guitar stage typically 22 uF, 35 uF, but that is going to probably roll off your Lo Freq's way too much for a bass. You probably need to go to 100 uF or more to get full range of a bass.
you are welcome to upload all you want here
btw, I mounted a green LED with a bleed resistor
it works, and cool to watch it power down
and, on the open test amp, its probably good safety 'monitor'
on power up and watching LCD meter, it could look like its also do soft start function
btw, it was weird the first time I powered it up
I only had half voltage, or less
but also noticed the first cap had the full 18V
well, I had 1ohm resistors between all 4 supply cap
and guess what, the middle resistor was gone, defect
I removed all resistors, and everything worked
btw, I mounted a green LED with a bleed resistor
it works, and cool to watch it power down
and, on the open test amp, its probably good safety 'monitor'
on power up and watching LCD meter, it could look like its also do soft start function
btw, it was weird the first time I powered it up
I only had half voltage, or less
but also noticed the first cap had the full 18V
well, I had 1ohm resistors between all 4 supply cap
and guess what, the middle resistor was gone, defect
I removed all resistors, and everything worked
Thanks Tinitus, if I come up with any interesting ideas when building it, I will send them. My preamp section for now is 2 stages of jfet. I may add a 3rd stage for more gain. I will jumper in the bypass caps and see how it sounds with and without them. Please let me know if you try that also and how it reacts on bass frequencies.
dont know if I should be happy or sad
happy because it works, and there is sound
but also sound that shouldnt be there....snerrring hummm
jfet is BL grade
drain resistor is 1.5K
source res is 15ohm
with modest voltage sag, it settled at 17.8V
I measure a little less than 9V across the drain resistor
and nothing when I measure across the source res
DC on output plugs is 'barely alive'
apart from the hum, very open and smooth midrange, none of the 'usual' harsness to hear at all
but the gain is excessive
with this alone between bass and poweramp, I can barely touch the onboard volume conrtrol on my bass
still work to do
but it works, thats something at least
happy because it works, and there is sound
but also sound that shouldnt be there....snerrring hummm
jfet is BL grade
drain resistor is 1.5K
source res is 15ohm
with modest voltage sag, it settled at 17.8V
I measure a little less than 9V across the drain resistor
and nothing when I measure across the source res
DC on output plugs is 'barely alive'
apart from the hum, very open and smooth midrange, none of the 'usual' harsness to hear at all
but the gain is excessive
with this alone between bass and poweramp, I can barely touch the onboard volume conrtrol on my bass
still work to do
but it works, thats something at least
a few small changes
LED/bleeder
resistor was mounted on the cathode/ground side
shifting the resistor to the anode/supply side lowered hum a bit
input-Z was set by a 1M5
changing it to 9K resulted in further improvement
connected as high-Z input on my head amp hum is almost acceptable now
dont know why, but the gain also seem to be more controlled now
and the sound is quite good
things to try, a regulated supply, and 2-channel output
LED/bleeder
resistor was mounted on the cathode/ground side
shifting the resistor to the anode/supply side lowered hum a bit
input-Z was set by a 1M5
changing it to 9K resulted in further improvement
connected as high-Z input on my head amp hum is almost acceptable now
dont know why, but the gain also seem to be more controlled now
and the sound is quite good
things to try, a regulated supply, and 2-channel output
just fooling around, practicing, and testing 
strangely, after inserting a hifi stereo preamp its now close to noise free
and just for the record, a describtion of this setup
bass guitar is plugged into a compressor effetc/'pedal' unit
and mostly because of its 12db gain and level control
signal then goes to the new jfet 'booster' proto
now with 2 channels out
and from there the signal goes to a hifi stereo preamp-buffer
originally built especially to drive the power amp I use
this setup sounds really great, and my best yet
now thinking about how to move on from here
I have a suspicion the jfet boz may not be the ideal high-Z input
but with some help it might become a great booster
strangely, after inserting a hifi stereo preamp its now close to noise free
and just for the record, a describtion of this setup
bass guitar is plugged into a compressor effetc/'pedal' unit
and mostly because of its 12db gain and level control
signal then goes to the new jfet 'booster' proto
now with 2 channels out
and from there the signal goes to a hifi stereo preamp-buffer
originally built especially to drive the power amp I use
this setup sounds really great, and my best yet
now thinking about how to move on from here
I have a suspicion the jfet boz may not be the ideal high-Z input
but with some help it might become a great booster
no doubt, this little 'simple jfet boz' is goodneed to think about how/where to use it
and why the noise almost goes away with the stereo hifi preamp driving the output
but I guess it also indicate theres nothing wrong with my jfet power supply
must be something other problem elsewhere
I have had problems with noise when not touching the strings
could be related to something on the instrument
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