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These transistors are general purpose ones. You can try these for audio applications:

2SA970 pnp low power
Vceo -120V Ic -0.1A Pc 0.3W Hfe(Typ) 200 Ft 50MHz

2N5401 pnp low power
Vceo -150V Ic -0.6A Pc 0.5W Hfe(Typ) 120 Ft 200MHz

To replace BD139 you can try MJE340 or TIP29C if you don't need high Ft or 2SC3298B, from Motorola in opposite way, the best replacement, in my opinion.

Vceo 300V Ic .5A Pc 20W Hfe(Typ) 135 Ft 10MHz

Vceo 100V Ic 1A Pc 30W Hfe(Typ) 120 Ft 3MHz

Vceo 200V Ic 1.5A Pc 20W Hfe(Typ) 160 Ft 100MHz

el doktor,
I had the same problems finding anything that starts with "b" in the US of A so much so that I had to have my brother buy me the stuff I needed in europe. The 2N and MJ or MP are the types commonly found here in the US. The bc559 is just a vile to-92 and the only thing it has going for is an hfe of 400. The bd139, which I hate, is your standard semiconductor used for driver stage. I found much higher quality devices in the japanese models from Toshiba and others. So, if you are building from scratch there are several alternatives to those transistors. If you need replacement parts is a different story. I don't want to push anything BUT I have a few bd139 and some bc560 which would be just fine, and better, as a substitute for the bc559. If you let me know what are you trying to do I can be more helpful.
I must have been writing at the same time as blmn so I would just add:

2N3904 for the bc559, though the current gain of either the 5401 or this 3904 is about 1/2 that of the bc559.

My all time favorite audio driver pair from Toshiba available at MCM:
2sa1837 PNP
2sc4793 NPN
Except if you need heatsinking the BD139, there shouldn't be any problem in using other transistors like the 2SC3298. It would only be a question of reversing the pins insertion, leaving the metal tab towards the other side.

To check on the pins you can use a DVM, though it's troublesome. Those having hfE meters would simplify the job.

I couldn't check on the MJE340 pins though.

The TIP types might be noisy on some positions.

On the low current types, usually having the base pin in the middle, it would only be a question of reversing the body.

Going for larger bandwidth types maybe a good thing.

In any case, Mouser does stock some European types, like the BC559 and BC550. The BD139 is not listed, but the 2SC3298 and MJE340 are.

At least this shouldn't stop you from going on with your project. What project is that?


2n3904 is an npn transistor is it not? I do have some 2n3906 in my junk box maybe I will try those in place of the bc559.
The project is DOZ ya I know its not an up to date design. I plan to build an Aleph 5 later when I can afford it. I still haven't finished my A40 but I have almost all the parts for DOZ in my junk box. So it will cost very little for me to attempt. For those interested this is where I found the PC board layout etc
I'm not a fan of DOZ but like I say I build it cheap after all how do I really know unless I try!
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