Hi...
One of my friends will give me some parts of old SA3 amplifier. Parts will include amp PCB's and PSU, unfortunately missing part is amp enclosure and heatsink with output transistors. Some modifications are existent on PCB's (he told me that) . Please help me with some guidance. I found on internet not so clear schematics of S300 (basis of SA3) and to put PCB to original state my idea is to put all new transistors and acquire all transistors for output stage.
My question is: is this transistor lineup in SA3
MPSA42 14 pcs,
MPS6571 8 pcs,
2N4250 2 pcs,
MPSA92 6pcs,
MJ15022 14 pcs,
Mj15023 14 pcs
2n3440 2 pcs
and 2N5413 2 pcs.
Thank you all for help on this technical topic...
One of my friends will give me some parts of old SA3 amplifier. Parts will include amp PCB's and PSU, unfortunately missing part is amp enclosure and heatsink with output transistors. Some modifications are existent on PCB's (he told me that) . Please help me with some guidance. I found on internet not so clear schematics of S300 (basis of SA3) and to put PCB to original state my idea is to put all new transistors and acquire all transistors for output stage.
My question is: is this transistor lineup in SA3
MPSA42 14 pcs,
MPS6571 8 pcs,
2N4250 2 pcs,
MPSA92 6pcs,
MJ15022 14 pcs,
Mj15023 14 pcs
2n3440 2 pcs
and 2N5413 2 pcs.
Thank you all for help on this technical topic...
Probably. Around now he is usually making the first cup of coffee. Or drinking yesterdays
Unfortunetely no, friend of mine who will donate amp parts to me told me that his amp is pure BJT without fets...on forum circulate this schematics but resolution is poor.
In this design FET's are better sonicaly than original transistors? FET's are my personal first choice for input stages.You could easily put 2sk170 fets in the input pair, omitting the input emitter resistors as well.
2SK170 are very, very hard to beat even today. And for the time (Threshold age), unbeatable.
The MMBT6429 looks like it would give the 6571 a run for the money. Surface mount of course, but very favorable characteristics.
The SOT-23 package should be managable for anyone with a fairly steady hand.
The SOT-23 package should be managable for anyone with a fairly steady hand.
SMD devices are last point of resort. SA3 is classic design so I will try to use FET's on input. To be on safe side, my idea is to put some sort of socket on PCB so alternation of devices will be possible and flexible. Any thoughts on this idea?
I can allready see it, 50 years from now, headlining the forum feed: the unpublished rites of Nelson Pass, found being used as stuffing for a Cube box, being brought into fruition. Right up there alongside Plato and Aristotle.Although there are many examples that didn't see the light of day.
I have a notebook from about 45 years ago, and I find that I used to take detailed notes on every experiment or idea.
Nowadays not so much...
Nowadays not so much...
