Harmon Kardon A401

[mr2racer]

Hello Everyone.

I have a Harmon Kardon A401 integrated amplifier. I bought it new in 1976. Later I sold it to a friend who returned as junk a few years ago. I replaced all the electrolytics and the output transistors. It works again and sounds alright. My question is if I replace the small signal transistors with up to date versions will it sound better? Or is it a waste of time and money? I've attached a list of those transistors. Most are no longer available so I would have to find substitutes.

Thanks, Kevin

 

[nigelwright7557]

I would never replace semiconductors in an amp unless they are definitely faulty.

Putting in faster transistors can result in oscillation and/or instability.
So I would just leave them be.

Electrolytics are the things that age fastest so replacing those was the right way to go.

 

[mr2racer]

Thanks Nigel. I'm a tube guy so I know little about transistors. Some of the electrolytics seemed to be glued to the boards. I guess that was the electrolytic leaking out of them?

 

[Ylli]

Most of the time the 'glue' is there to mechanically stabilize the part. Electrolytic capacitors tend to be a bit massive, and gluing them to the board helps prevent mechanical stress failure of the leads. But leakage is certainly possible.

 

[Mooly]

Changing the transistors won't change the sound quality at all... and as Nigel hints at, if you make a wrong choice it could bring new issues to the table.

 

[huggygood]

+1