MPP

[MiiB]

This is the noise simulation through at the output cascodes....Must say that I am not too familiar with noise simulation, and have not seen how they correlate with reality, but with the BC-models its clearly a magnitude lower than with the 550C/560C's

 

[Joachim Gerhard]

Why not using BC327, 337 everywhere ?

 

[Salas]

LT Spice can be spot on if the models allow. Enough models are sorely lacking for such analysis unfortunately.

 

[Salas]

Why not using BC327, 337 everywhere ?

Low Rbb' with enough hfe is best bet.

 

[Joachim Gerhard]

Should we divide that by the amplification factor ?

 

[Joachim Gerhard]

You can not beat the Hitachis, Toshibas and Rohms on that but with the Faulkner circuit we come very close and use transitors that everybody can get. That is the plan i think.

 

[Salas]

Should we divide that by the amplification factor ?

No, you should integrate it to RMS for given bandwidth.

 

[Salas]

You can not beat the Hitachis, Toshibas and Rohms on that but with the Faulkner circuit we come very close and use transitors that everybody can get. That is the plan i think.

2N4401,4403, 2SC1815, 2SA1015, BC327,337 will be fine.

 

[Joachim Gerhard]

Rbb`is 30 Ohm in the BC337 and the PNP should even be more quiet. We degenerate heavy anyway. That gives us 6,25 Ohm anyway. The 8 BCs even when we say the PNP is only as good as the PNP would only add 3,75 Ohm. I would say, mission accomplished.

 

[Salas]

How's the bandwidth? A bit high Cob those but the degeneration should ease it.

 

[Joachim Gerhard]

Sure, i forgot the bandwidth issue. Salas, i agree on the transistor choices. Even when you have a big stash of BC550C, BC560C it is not that bad. I have a Hawksford LFD battery phono that cost the not small sum of over 10.000,- DM in it´s day that has just that.
2 x 4 BC550C, BC560C with 50 Ohm degenerated each. Ok, that is plan B just in case.

 

[Salas]

Pricing is a matter of promotion & positioning in the market roulette, also precision & scale of manufacture, running a firm cost. But you know all that much better. Still, physics don't know money fortunately for DIY.

 

[Joachim Gerhard]

Yes, they have 12pF Cob. But look at this ...
Virtually no early effect at the current we drive them.

 

[Joachim Gerhard]

Malkolm chose them over the Rohms so that was a purely technical choice. That stage was originally designed for SME but they never build it. So Dr.Bews took it to market so that it does not land in the waste bin. Greediness can not be. When there are 20 in this world then this is much.

 

[Salas]

Yes very low slope to project to the left. Looks like a wise choice for the purpose. I hope they will be good noise on FFT too, bcs with the process licensing you never know who is who silicone.

 

[Salas]

Malkolm chose them over the Rohms so that was a purely technical choice. That stage was originally designed for SME but they never build it. So Dr.Bews took it to market so that it does not land in the waste bin. Greediness can not be. When there are 20 in this world then this is much.

Special products are just that. Can not be judged in arbitrary cost terms. As long there is a market for them, all well.

 

[Joachim Gerhard]

I trust Sampler on this. This transistors are made by a lot of companies. I ordered Diotec and will report.

 

[Joachim Gerhard]

http://diotec.com/tl_files/diotec/files/pdf/datasheets/bc337.pdf

 

[Salas]

Can group 40 be specifically ordered?

 

[Joachim Gerhard]

Yes, at Reichelt. 0.04€ a piece.