Anybody know replacements for 2SC3329 and 2SC1246?

[tusntuk2]

Please help me understand what would be good replacements for 2sc3329 and 2sc1246 transistors in my phono preamp section in a NAD 7140. They seem to be making lots of white noise, even with no input. Also seem to be hard to find! Thank you!

 

[ivandezande]

For the 2SC1246 I would try something like a BC33716BU, looks like you just need a general transistor that doesn't even need that high of voltage ratings but the performance isn't probably going to be the same. Can't really help on the C3329, most ultra low noise transistors in a normal package aren't around anymore it seems.

 

[FootFungus]

Have you tried it with the input shorted? That would be the real test.

The 2sc3329 is a low Rbb type transistor. I think B&D has the 2SC254(5-7) which is the only thing available that is close. The other available good low rbb option is the ZTX851 although its quite a different device. Worst case, try the BC337 in place of the 2sc3329 and see if the situation improves. The pinout on the BC337 and ZTX851 are different than the 2sc3329, so be careful.

 

[tusntuk2]

I did go back and try the volume (phono section) with the inputs shorted, and it was silent. Didn't know to try that - what does it mean or suggest? It's beginning to look like the c3329 is really hard to replace.

 

[FootFungus]

If its silent with the input's shorted then all is well. If had still been noisy with the shorted input then the source of the noise would likely be something in the amp (transistors, regulators, resistors, etc).