Tweeter Resistor value question.

[Black Stuart]

I am in the process of externalising the passive x/overs for my Heybrook Sextet 3-way speakers and inadvertently naffed one of the Tonigen tweeter resistors. I decided that with external x/overs it will make it easy to experiment with different values. So I ordered 1 and 1.5 Ohm metal film 1%.

The resistors arrived today and they are no way 1% - the 1 Ohm measure 1.2 and the 1.5 measure 1.7/8 Ohm. I wanted to experiment using cheap metal film and when I am satisfied with what I hear to replace with Z foils which will not introduce any brightness to the Tonigen sound.

It could be that the original 1 Ohm is the right value but I might as well try both the 1.2 and 1.7 but if I find I don't like these values, where can I buy (cheaply) true 1 Ohm metal film resistors?

 

[Lojzek]

It is probably your meter that induces the extra resistance. Try to subtract the wire resistance or whatever error the meter may be causing. Read dcr of the wires/probes shorted.

 

[Galu]

To back up what Lojzek has just said, the meter leads will have their own resistance in the order of a few tenths of an ohm.

You need to subtract that extra resistance when using a low resistance scale.

P.S. Your resistors are fine.

 

[lowmass]

the contact resistance where the leads plug into meter AND the "wiper" inside meter on the ohm dial all can be an issue.
Twist the leads in the meter back and forth a few times AND turn the dial back and forth a few times. This to clean contact areas, then hold leads together at the points and take a reading. Now subtract that reading from whatever u measure.

 

[rayma]

Even so, the readings will vary each time using simple probes. You could solder wires to the resistor,
and solder banana plugs to the other ends of the wires for the meter, for more consistent readings.
Also just trusting the resistor marking is fine for this purpose. It's quite unlikely they are bad.

 

[Black Stuart]

Thanks to everyone for the replies and of course they all make sense. I did think immediately I got the 'wrong readings' that the very low values had something to do with that and yes I will do those experiments.

I don't think I would ever have bought kit amps or modified gear without the net to ask questions on.

For those too young to know - without the net, where could you find answers - libraries, writing letters to magazines - Tim Berners-Lee et al - thank you.