noise of arrays

[Franck PISSOTTE]

 >> Does anybody know how noisy cheap transistor arrays (CA3046)
 >> are, compared with cheap low noise transistors (BC550)?
 >> The reason why I'm asking: I'd like to build this ARP all pass cascade,
 >> and I wonder if I should use arrays or selected discrete transistors.

 the LM3046,LM3086 have: (NS data book)
f=1kHz, Vce=3V, Ic=100 microA, Rs=1kohm  Typ Low Frequency Noise 3,25db

>From RTC: at ic =2 mA
BC109 BC179  1,2 dB
BC549, BC550 1,4 dB
BC559        1,2 dB
BC560        1 dB
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SSM2210: Ic=1mA f=1kHz 0,85 nV/ \/ Hz   (half price of a MAT)

Don't have the knowledge to tell any conclusion.
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if anyone know how to convert nV/ \/ Hz to dB please tell me.

put several 3046 in //  to reduce noise but increase price.