suggestions for transistor upgrade

[miner79]

Any thoughts on a the best sounding transistor to upgrade BC550C's used in a Creek OBH8 MM phono stage. There are 5 per channel in series as near as I can tell. I have some 2SC2547E transistors but apparently they are not direct replacements, because the preamp does not work with these.

Any help would be appreciated.

Bob

[gaborbela]

HI Miner
I'm looking for 2547E transistors , I would like to purchase a dosen or more would you please let me know were you buy your transistors .
May be if you not using them I would take them fro your hand .
Please let me know .
Regards

[Mooly]

Hi,
Its the characteristics ( specifications ) that matter. Things like junction capacitance, hfe, fT etc.
Transistors don't ( some will disagree ) have a sound, they have properties determined by the laws of physics.
BC550 and 2SC2547E have different pin outs. With both in front of you flat surface uppermost, it's E,C,B for the 2SC2547 and C,B,E for the BC550. Google them for the data sheets.
You can't just swap transistors willy nilly without knowing how they are used in the circuit

[AndrewT]

Hi,
the 2547e may be a good substitute for the 550, but it depends very much on how the circuit has been set up to suit the parameters of the 550.
If the bias for the 550 suits the 2547e, it may turn out to be slightly quieter. But Vbe is significantly lower and this may upset the currents.

If you bend the legs of the ecb pin out, you can fit these.
With the flat face towards you,
Bend the left pin1 E towards you and slightly to the right.
Bend the middle pin2 C away from you.
Bend the right pin3 B slightly to the left.
You now rotate the body to 90degrees cf. the bc550 and the three pins fit the cbe pads arrangement.

If you want you can use the tube insulation from 0.6mm solid core over the legs to prevent shorting of the bent pins.