Does this mean the zener and the smd JFETs should be upgraded with 30v or more parts? More coffee needed.
no reason to change neither value nor power of zeners used
with normal use and procedures, nothing wrong will happen
zener is there to cover mishaps and possible power-on transients, in case someone get to different cap values (before and after series CCS)
and, this time, I can bet it did what's placed for - JFet is still alive
again, who knows what zap you made, while having things wrongly connected
with normal use and procedures, nothing wrong will happen
zener is there to cover mishaps and possible power-on transients, in case someone get to different cap values (before and after series CCS)
and, this time, I can bet it did what's placed for - JFet is still alive
again, who knows what zap you made, while having things wrongly connected
OK 🙏
The JFet's all measure about 120R D-to-S so maybe I am in luck. Will try a new zener later in the AM, and fire it up connected correctly to the load.
The JFet's all measure about 120R D-to-S so maybe I am in luck. Will try a new zener later in the AM, and fire it up connected correctly to the load.
Quick/beginner question. I understand R4/R17 are the IV resistors of D1, but in addition to these two, would R9 and R11 be considered in the signal path?
R9 is gate stopper, of course that it is in signal path
though, if you enjoy being anal, chasing "better than proper industrial metal film", be my guest
R11 is practically load for Q2 source follower; final element where current swing being converted to voltage swing, so - yes - it is in signal path
again what I wrote in second line
though, if you enjoy being anal, chasing "better than proper industrial metal film", be my guest
R11 is practically load for Q2 source follower; final element where current swing being converted to voltage swing, so - yes - it is in signal path
again what I wrote in second line
Thanks ZM. If you ask my family, I was born anal 😂
Just curious/learning. I am playing with different DAC chips and resistors are not in focus at the moment.
Just curious/learning. I am playing with different DAC chips and resistors are not in focus at the moment.
Another question...
For the beautiful array of 'output' capacitors, is the role DC blocking, and is the value (15uF) selected to have appropriately low roll off in the context of the preamp input impedance?
Cheers -
For the beautiful array of 'output' capacitors, is the role DC blocking, and is the value (15uF) selected to have appropriately low roll off in the context of the preamp input impedance?
Cheers -
I already wrote about that:
- have drekload of Philips MKC
- have enough nice 10uF elcos
- they look nice that way
- put them plenty, no need to waste battery in Casio calc
Thanks ZM. I can be a bit dense...
You must have anticipated the next question.
So, going into a 50k input impedance preamp, if I get it right, the -3db roll off is about 0.2 hz. At some point, I gathered some 1uF caps for DC blocking in a tube DAC and I was just wondering if it might be worth trying them in the D1, if/when I get bored. It seems, 1 uF would give a 3.2 hz -3db roll off. Now my Casio is limited to very basic functions and I may have this all wrong.
And not asking you to bust out your calculator..
Cheers,
Soren
You must have anticipated the next question.
So, going into a 50k input impedance preamp, if I get it right, the -3db roll off is about 0.2 hz. At some point, I gathered some 1uF caps for DC blocking in a tube DAC and I was just wondering if it might be worth trying them in the D1, if/when I get bored. It seems, 1 uF would give a 3.2 hz -3db roll off. Now my Casio is limited to very basic functions and I may have this all wrong.
And not asking you to bust out your calculator..
Cheers,
Soren
F=1/(2*Pi*R*C)
just play with it ...... I'm not loosing my sleep thinking of better cap than combo made of polycarbonate + industrial quality elco
find your fave and stay stubbornly with that ....... waste your energy on other things
just play with it ...... I'm not loosing my sleep thinking of better cap than combo made of polycarbonate + industrial quality elco
find your fave and stay stubbornly with that ....... waste your energy on other things
@zm, thanks very much for the files and background, I have a populated board ready to go, two questions:
1) what's the procedure to adjust offset?
2) I will power the board w/ UltraBiB 1.3 shunt regulators. Is 30V to power the D1 good?
The only curious thing about firing this up, is that you measure and adjust DC offset on the INPUT.
Fed it +/- 30V and let it cook for 20 min without the DAC chip connected to the input. Measure offset on the inputs and adjust. Once you are happy, connect the DAC output and enjoy.
If bypassing the on board PSU, you can always study my photos for how not to connect it 😊
Fed it +/- 30V and let it cook for 20 min without the DAC chip connected to the input. Measure offset on the inputs and adjust. Once you are happy, connect the DAC output and enjoy.
If bypassing the on board PSU, you can always study my photos for how not to connect it 😊