Jfet BOZ

[Zen Mod]

not exactly on par

B1 and JBOZ are just having context and goals , so final quality is different

[mhouston]

@tinitus: After building both the B1 and quite a number of BoZ the B1 sounds better but I need gain to for my low gain tube power amps. So BoZ works for me. But BoZ (or my BoZSE) is an excellent sounding dead simple jFet preamp.

[tinitus]

I increased the drain res to 3K2ohm
source res is still 15ohm
now I measure 16V over the drain
and measure over source res, it circles around -1mV and +1mV

totally different values
now it sounds like fresh running water

[mhouston]

With my BoZSE and a 24V supply I can get 17V swings with no clipping into 10K.

[tinitus]

Originally Posted by tinitus

I increased the drain res to 3K2ohm

turned into a very nice distortion machine

back to 1K5 drain res, and 15ohm source

shows the input is very easy to overdrive
I have 850K to ground, and cant go any lower
1M is probably 'safer'

maybe gate/series res could be increased

[tinitus]

related power supply
well, I never tried those little 1ohm series resistors, and thought this might be a good moment for it
and I can only say ouch
this happened yesterday, before any of my posts here
I didnt notice at first, but the downwards slide had begun, hunting other 'sound improving' adjustments
which probably gave me a clown award
but also learned something very interesting

fortunately that sweet sound I had experienced earlier came back instantly when I removed the series resistance
it may lower noise, and some claim quite a lot
but to my ears it definately kills this little curcuit, and what it does best
for me personally, series resistors are out, sorry

[juma]

Originally Posted by mhouston

With my BoZSE and a 24V supply I can get 17V swings with no clipping into 10K.

I suppose it's 17V peak-to-peak i.e. 6V RMS ?

[mhouston]

@Juma: Yes peak to peak.

[tinitus]

I have seen a se output buffer with jfet and a bjt inserted in the drain, and connected to source(out)
dont know what its called
thought it might be worth a try since i found some older BC547

[tinitus]

searching, but not much to find, other than it looks like a ccs turned backwards
and bjt appears to be biased through the jfet drain resistor