Need help identifying transistors

Hi, I’m looking for replacements for the two transistors pictured. I did some research and it looks like the manufacturer is Sanken Electric. Any help would be great. Thanks

  1. 2SD2390-ND

  2. 2SB1560-ND

Do the 67/66 P numbers matter?

Hi awilson17

I believe 66/67 are internal manufacturer part markings and do not have meaning. According to it is the last letter that has meaning. It is available in three different gain types that can be determined by the last alphabet used below the part number. So if the last alphabet is “O” then the gain will be from 5000 to 12000, if the alphabet is “P” then the gain will be 6500 to 20000, and if that alphabet is “Y” then the gain will be from 15000 to 30000.

The products offered above have less gain but are great options and should work well for most applications.

Ok. So one with lower gain is fine even if I’m using it in an audio application?

Also, the transistors for the other channels of the amplifier have the same 66/67 markings on them if that means anything

no, as stated before it has no effect on the part performance.

Hi awilson17
There is usually enough headroom in the internal & external volume or gain control to offset the lower gain in the transistors.

-In a multi-channel amp, and “if” the replacement transistor gains are substantially different (usually not the case) you will want to replace the other channels transistors to match, unless the other channels have their own separate adjustable crossovers then replacement may be optional

Unless they’re broken, I wouldn’t.

Respectable linear amplifier designs employ negative feedback techniques to compensate for variations in component behavior, which occur in response to things like temperature as well as production variation. So long as the open-loop gain is large, it’s exact value doesn’t matter much.

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Agreeing with Rick, it’s not necessary to replace all channel transistors unless they are bad or you are looking for increased reliability after assembly, as the remaining working transistors may have limited life left if those channels have similar usage hours.