After a few hours listening, I'm very thrilled, what a great little amp, no harshness at all, seen many describe it as crystal clear, I will join this club.
I have more p3a pcb and decided to try this combination with sanken 2sa1216 and 2sc922.
I saw rod had used the same pcb as p3a for a class a version, with lower rails like the one I showed further up in thread, I have two more toroidals left and all parts except chassis.
I might be asking for trouble, theese are much faster devices
I have more p3a pcb and decided to try this combination with sanken 2sa1216 and 2sc922.
I saw rod had used the same pcb as p3a for a class a version, with lower rails like the one I showed further up in thread, I have two more toroidals left and all parts except chassis.
I might be asking for trouble, theese are much faster devices
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@amplidude
Odd placement of parts: Q9 (BC546) should be close to Q6 (BD140) for proper function.
Odd placement of parts: Q9 (BC546) should be close to Q6 (BD140) for proper function.
You're probably right, but I've been through most of the classics.
Will spend some days with some fine tuning, finding a perfect bias level.
But as said will post measurement done with quantasylum.
Have started a new p3a running class A , one of red elliots projects, still have two 300 watt 20 volt toroids.
Will spend some days with some fine tuning, finding a perfect bias level.
But as said will post measurement done with quantasylum.
Have started a new p3a running class A , one of red elliots projects, still have two 300 watt 20 volt toroids.
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Got tempted by an offer I couldn't refuse, a serious hifi guy bought my p3a, without seeing or listening to it, he just liked its design, he has mark Levinson amps and speakers in same price range, I believe they are lowther horns.
I told him that this little amp in my ears probably match his current amps or better in musicality, but off course lower watts, he told me he never plays loud music, classic jazz and the like, and his speakers are 100 db plus effective, an older gentleman.
I asked him to give me his honest opinion once he has used it some days, I'm really curious what his verdict will be.
It's in shipment now, he should receive it tomorrow or day after.
I told him that this little amp in my ears probably match his current amps or better in musicality, but off course lower watts, he told me he never plays loud music, classic jazz and the like, and his speakers are 100 db plus effective, an older gentleman.
I asked him to give me his honest opinion once he has used it some days, I'm really curious what his verdict will be.
It's in shipment now, he should receive it tomorrow or day after.
Been working on my new p3a today
Input. Bc550c matched tight with dca pro
Vas driver . 2sa1145 Y . Cob 2.5pf Ft 200 hz
Driver. Tta004b ttc004b 12pf 100 hz
Bias. Tta004b
Output. Sanken 2sa1216 2sc2922 Y
Powered it up through 50r resistors, seems to work so far, no oscillation.
Next step heatsinks and full power.
100r degeneration on input
Rubycon rx30 electrolytic capacitors 130 degrees.
All resistors except 3k3 are 0.1% 25ppm vishay sfernice velwyn
Input. Bc550c matched tight with dca pro
Vas driver . 2sa1145 Y . Cob 2.5pf Ft 200 hz
Driver. Tta004b ttc004b 12pf 100 hz
Bias. Tta004b
Output. Sanken 2sa1216 2sc2922 Y
Powered it up through 50r resistors, seems to work so far, no oscillation.
Next step heatsinks and full power.
100r degeneration on input
Rubycon rx30 electrolytic capacitors 130 degrees.
All resistors except 3k3 are 0.1% 25ppm vishay sfernice velwyn
Attachments
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I've made P3A long time ago Rev.A. PCB ordered from Elliot. In meantime I used another amplifier. But a few days ago I wanted to check again my P3A. After so long time amplifier started to work without problem. Bias current was adjusted to 1,5A to get A class as it is in P3B project. For my ears A class sound better. First tried on my OB speakers but after I reconnected my Magnepan LRS. Instrument was still connected but I was surprised that bias current is changing in rhythm of music. Reconnected again to OB, bias stay stable. I know that Magneplanar has complicate load but I didn't expect variable bias current. Anyway amplifier is working perfectly with complicate LRS speakers.
A bit more progress, the p3a are just how I want them now, i got them mounted on nice sinks, and added epcos sikorel 10000uf 63v just up against the pcb to minimize inductances, tomorrow the modules are ready to go into their chassis.
Man I like this amp, the best, most pleasing sound I've ever heard. The sikorels will be fed by a crc capacitor bank
Man I like this amp, the best, most pleasing sound I've ever heard. The sikorels will be fed by a crc capacitor bank
