Ok thanks for the update Ivan and Andrew.
Please see below photo of my progress, I populated the boards with the parts available in my shelf. I will be receiving other parts from Farnell by next week and will do testing soon.
I'm working on assembling the PSU card and found two minor mechanical issues. For C10, 100uF 50V, the component lead spacing is 3.5mm but the board hole spacing is 5mm so the leads must be formed to fit. For J10 the Phoenix connector I bought has three plastic locator tabs intended to go into holes in the board. There are no holes in the board for the tabs so I cut them off. The connector I bought is Phoenix 1725669 - can anyone confirm if this is the right part?
I came up with the same part, at least on Mouser. Don't think that is the correct part. The footprint for that connector has six holes, one set for the leads, a second set for the plastic tabs. The plastic tabs are intended to hold the terminal block steady while torque is applied to the screw. Without them, the connector has a tendency to twist. I have other connectors without the tabs. I have not looked at the lead spacing on C10.
Thanks Bonsai!
Finally I decided to use the following drivers (between VAS and output):
2sb1086a-Q/2sd1563a-Q
These transistors purpose is for low frequency audio amplifier driver stage and their HFE is constant up to 300ma compared to about 30ma for the ksa1831/ksc3503. Also, I am able to get 190 HFE for sb/sd type compared to about 145 for the KS type from the stock I have. I understand that Bonsai gave its blessing for that then it should respect the idea of its design....
Also for the output I have selected the best match ( they are from the same lot nimber) for VBE and was able to get 0.486 v for both NPN and 0.484 for both PNP. I am using 1% tolerance 0.30 ohm from the same lot number for RE.
Fab
Finally I decided to use the following drivers (between VAS and output):
2sb1086a-Q/2sd1563a-Q
These transistors purpose is for low frequency audio amplifier driver stage and their HFE is constant up to 300ma compared to about 30ma for the ksa1831/ksc3503. Also, I am able to get 190 HFE for sb/sd type compared to about 145 for the KS type from the stock I have. I understand that Bonsai gave its blessing for that then it should respect the idea of its design....
Also for the output I have selected the best match ( they are from the same lot nimber) for VBE and was able to get 0.486 v for both NPN and 0.484 for both PNP. I am using 1% tolerance 0.30 ohm from the same lot number for RE.
Fab
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Fantastic!
We're you able to dial out the offset ok and set the quiescent current easily?
Lets know how it sounds.
The DC offset can be adjusted easily with input shorted. However, I need to use DC offset feature of my function generator so the DC stay the same (zero). That brings me the concern if the pre-amp has a small DC component then it is amplified by the power amp by its gain (no feedback cap)... Normally I use a coupling input cap to prevent that Dc but the input cap selection generally affects the overall sound ...
The quiescent current can be easily adjusted too but I am just trying to experiment and I still do not know if it is stable (temp compensation) after a while ( it was late yesterday...).
For the sound it will take a while since I only have one heatsink at this moment....
Also since I have not started your power supply and I entend to use another of mine I need to connect the NX amp over current protection to my existing other pcb DC protect circuit .... I think I have found a way but will require your blessing if you do not mind...
Thanks Bonsai to share your design with us.
Fab
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What coupling cap do you recommend (to not degrade the overall performance). I do have in stock Clarity cap ESA 3.3uf.
Here is the inductor I use (for now):
http://www.mouser.com/ds/2/427/ihd-239901.pdf
Fab
Nice one Fab, I'm still waiting for the other parts. Let us know how it sound
Thanks Junie.
I still need some time before enjoying the music...
Finally I could no more support the pressure and changed my inductor by looking in my electronic junk parts...
However I could not find 12awg wire...
Fab
