1% metal film resistors - overkill?

[LowRedMoon]

I'm going over a couple of receivers that I'll be giving to friends - a Harmon Kardon 330B and a Sansui QRX4500.

One thing that I've nticed is that the HK receiver is packed full of 10% tolerance resistors.

This novice has been led to believe that 1% resistors should be used whenever possible. Believe me - I'm working on my understanding of things.

But for now - would it worthwhile to replace them with 1% metal film resistors? I probably have all values on hand.

Thanks, folks.

[poobah]

LowRedMoon,

Nothing wrong with 1%'s at ALL. 1%'s are the only thing I put in my bins. Not because because they're "better"... it just minimzes what I have to keep around... you can always use a 1 in place of a 5 or 10... doesn't work the other way though.

10% resistors have all but gone away... 5%'s are on their way as well. Will it make a difference in a circuit designed for 10%'s? ...not really... might help once in awhile... but it will never hurt. And they don't cost that much more these days.

[CaliforniaBob]

There's another benefit to using 1% metal films and that's the
noise level drops dramatically. Background noise disappears and
music pops out at you.

Highly recommended since they are very reasonable to buy.

[peranders]

My recommendation is to let them recievers be. The risk is very big that you never get those working again if you start to mess with the resistors. It's not very likely that you'll get significant improvements worth the trouble.

[janneman]

Originally posted by CaliforniaBob
There's another benefit to using 1% metal films and that's the
noise level drops dramatically. Background noise disappears and
music pops out at you.

Highly recommended since they are very reasonable to buy.

There are two issues here. The tolerance of the resistors should not be critical. If HK uses 10% tolerance that means that they have competently designed the circuits to be stable and predictable even if resistors slightly vary in value. Going to 5%, 2% or 1% wouldn't make a difference.

The other is the type of resistors. The 10% types may be carbon film types. Replacing them with metal film types CAN lower the noise floor, but it depends on a lot of other factors too.

Jan Didden

[Netlist]

I was told to never use metal film in the HF part. So if you plan to go on anyway, leave the carbon in there.
Replacing some old capacitors might be worthwhile though.

/Hugo

[jean-paul]

Originally posted by Netlist
I was told to never use metal film in the HF part. So if you plan to go on anyway, leave the carbon in there.
Replacing some old capacitors might be worthwhile though.

/Hugo

True. Leave carbon resistors where they are in tuners. I am also cautious when electrolytic caps in the HF section are concerned.

[peranders]

.... so the conclusion is:

The odds to make a substantial lift in the performance with no schematics and no insight in the design is rather poor.

My boring advice is to let those receivers be.

[janneman]

Originally posted by jean-paul


True. Leave carbon resistors where they are in tuners. I am also cautious when electrolytic caps in the HF section is concerned.

Jean-Paul, Hugo,

What is the reason to leave the carbons in the tuner scetion?

Jan Didden

[peranders]

The very reason is don't mess in radio circuits. The second reason _may_ be that old carbon resistors had good HF properties.