A one transistor (possibly jfet if you like them) input follower and a one-transistor Baxandall bass/treble control comes to mind.
the amplifier has all of the gain one would ever need and you can change it by changing the value of R11, so the thing we should be building is an current buffer and we should find out where to inject the volume potentiometer.
something like this, the output capacitor is here just for demonstration purposes, VR1 A/B is the volume control pot
I find this great sounding as headphone amp and pre.
Post in thread 'DIY Class A Headphone Amp suggestion' https://www.diyaudio.com/community/threads/diy-class-a-headphone-amp-suggestion.415623/post-7752669
Post in thread 'DIY Class A Headphone Amp suggestion' https://www.diyaudio.com/community/threads/diy-class-a-headphone-amp-suggestion.415623/post-7752669
Only one real problem with this… 8 ohm minimum load. Put in bigger transistors that won’t fry on 4 ohm and you run out of beta.
Is Wattnik, the original poster, still around? My advice to his design were to forget about slowish TIP41/42's as drivers and to leave the original 2N2222/2905's at that spot, or to put in BD139/140's. There's really no need to provide the same type of transistors as power and driver devices.
Best regards!
Best regards!
Don’t matter - a lot of folks interested in these circuits. They get you something that makes listenable sound (can be quite good) with little investment and pretty good chance of success within a couple of hours.
I think it (original design) settled on BD13x outputs with small signal drivers. Which works fine on 12V. TIP41/2 are the go-to for supplies up to 36, maybe 40V. TO-92 (or TO-18) drivers still work. The BDs will work driverless, but start showing their age at 4 ohms because the beta takes a dive and it distorts a lot. Also a little iffy on 19V. Trying to use TIPs driverless results in too much distortion no matter how you slice it because NPN beta never gets very high to begin with (PNP starts up above 100 but drops to NPN levels at 2A). They just need drivers, period. Bottom line is when you start making the circuit bigger (more volts more watts) the required complexity is higher.
I think it (original design) settled on BD13x outputs with small signal drivers. Which works fine on 12V. TIP41/2 are the go-to for supplies up to 36, maybe 40V. TO-92 (or TO-18) drivers still work. The BDs will work driverless, but start showing their age at 4 ohms because the beta takes a dive and it distorts a lot. Also a little iffy on 19V. Trying to use TIPs driverless results in too much distortion no matter how you slice it because NPN beta never gets very high to begin with (PNP starts up above 100 but drops to NPN levels at 2A). They just need drivers, period. Bottom line is when you start making the circuit bigger (more volts more watts) the required complexity is higher.
There is the BD43x series, similar to BD13x but with higher current/power rating. I think they can be used driverless too.
Both amplifiers top out at 4W becuse of the bd13x transistors and their 1.5A limit
Not only is that a reliability limit, but they ain’t got $*** for gain above an amp. Flat gain till it falls like a stone starting in the 300 mA range.
Mosfets can be used driverless, but they also chew 4 volts apiece as followers.
Mosfets can be used driverless, but they also chew 4 volts apiece as followers.