Ono Bipolar Transistor Replacement

rsbay · 10th May 2008, 08:26 AM

Hello,

what is the best replacement for

2SA991
2SC1844

in the Ono phono preamplifier?

Thanks for your help

Ralph

Nelson Pass · 11th May 2008, 04:59 PM

These are listed as low noise and high gain, with a 60V rating.

In point of fact, the critical ones are the NPN cascoding on the MC stage
and the current source for the diff pair, where they will see about
30V.

I don't know of a direct replacement, but looking at my parts supply,
I would try the MPSA18 or MPS6571 for these two parts and use
a high quality 60V device elsewhere.

10th May 2008, 08:26 AM	#1
rsbay diyAudio Member Join Date: Apr 2004 Location: Erkelenz	Ono Bipolar Transistor Replacement Hello, what is the best replacement for 2SA991 2SC1844 in the Ono phono preamplifier? Thanks for your help Ralph

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11th May 2008, 04:59 PM	#2
Nelson Pass The one and only Join Date: Mar 2001	These are listed as low noise and high gain, with a 60V rating. In point of fact, the critical ones are the NPN cascoding on the MC stage and the current source for the diff pair, where they will see about 30V. I don't know of a direct replacement, but looking at my parts supply, I would try the MPSA18 or MPS6571 for these two parts and use a high quality 60V device elsewhere.