SIT Nemesis! Good dog!
Thank you very much for the addendum. One of the qualities of your articles is for me, that they are very easy to understand without losing any profoundness. Non-fiction book author qualities...
Too bad there's another matter altogether in the new version of the Nemesis: First the OPT, now the SIT. OK, time will tell. The project is too seductive to give it up. I mean to switch to or concentrate on the ZEN DeLite variations. I also presume that both projects complement each other.
Thank you very much for the addendum. One of the qualities of your articles is for me, that they are very easy to understand without losing any profoundness. Non-fiction book author qualities...
Too bad there's another matter altogether in the new version of the Nemesis: First the OPT, now the SIT. OK, time will tell. The project is too seductive to give it up. I mean to switch to or concentrate on the ZEN DeLite variations. I also presume that both projects complement each other.
So I built up a basic pair of monoblocks very similar to these, even before I saw the article ;-) Transformers are a pain to come by, so I wound my own. Quadfilar wound on Hammond SE transformer cores, about 110 turns of 18ga magnet wire per winding, 2 windings in parallel for the primary, two for the secondary, for a 1:1 ratio. Circuit looks a LOT like the DeLite fig7 circuit with the tranny instead of the light, and I've got about a 23V rail. Originally built with IXTH6N50D2s with 1ohm source resistors for about 1.6A, then changed to R085s with 2ohm source resistors for about 2A. Sound with both is QUITE good, and if you don't mind winding your own transformers, the results are worth the effort....
One FET, three resistors, one transformer, bliss...
Roscoe
One FET, three resistors, one transformer, bliss...
Roscoe
From reading the original article on the Arch Nemesis the output is about 6W. Is there any way of increasing this to 10W or a little more? Maybe raising the B+? I have Alpair 10 full range units which are about 88db, though I have a smallish room and don't listen loud.
I'm in UK and Farnell is stocking the R550, R100A and R063A - any of these of interest for higher power output? (R085 is currently out of stock).
Andy
I'm in UK and Farnell is stocking the R550, R100A and R063A - any of these of interest for higher power output? (R085 is currently out of stock).
Andy
Last edited:
Hi all, I'm just trying to better understand this circuit.
In Nelson's Arch Nemesis article he describes the use of the drain resistor (R2) to decrease the drive impedance for the output transformer. How exactly does adding this resistor achieve this? Your advice is appreciated!
Thanks,
Greg.
In Nelson's Arch Nemesis article he describes the use of the drain resistor (R2) to decrease the drive impedance for the output transformer. How exactly does adding this resistor achieve this? Your advice is appreciated!
Thanks,
Greg.
The resistor on the primary sits in parallel to the drain (output) resistor of the active device: one side of the resistor is connected to the drain, the other side is connected to signal ground (power supply is signal ground for ac).
So this resistor is in parallel to the drain output impedance and this parallel combination is of course the driving impedance on the primary.
Jan
So this resistor is in parallel to the drain output impedance and this parallel combination is of course the driving impedance on the primary.
Jan
imagine/take xformer primary as plain resistor of pretty big resistance ; NP wasn't thrilled with performance with so high-impedance load , so simply put lesser impedance in parallel - to decrease overal load impedance
for said input voltage , current through SIT will vary for some amount , resulting in appropriate voltage swing across loading impedance
for said input voltage , current through SIT will vary for some amount , resulting in appropriate voltage swing across loading impedance
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.