Please help me with a crossover resistor value

[Steever]

I’m in the process of ordering bits for a crossover rebuild. The speakers are a two way with passive network. 
 

This resistor value is stumping me. 
 

 

50R?
Is this 50 Ohms?
It just doesn’t make sense if it is when the whole load with all bits and drivers is 8 Ohms nominal.

 

Any ideas appreciated. 

[mwhouston]

If you are replacing parts, unsolder or cut it free and measure it. 

[Steever]

26 minutes ago, mwhouston said:

If you are replacing parts, unsolder or cut it free and measure it. 

Yes, I’m thinking that’ll be on the cards for tomorrow. 
cheers. 

[RoHo]

Probably is 0.5 ohms

eg  https://www.reichelt.com/de/en/wirewound-resistor-axial-5-w-0-5-ohm-10--arc-acs5s-r50-k-p233146.html

Edited August 17 by RoHo

[Steever]

3 hours ago, RoHo said:

Probably is 0.5 ohms

eg  https://www.reichelt.com/de/en/wirewound-resistor-axial-5-w-0-5-ohm-10--arc-acs5s-r50-k-p233146.html

 

Thanks.

 

I got the nippers out in the end and measured DC resistance at 1 Ohm. It actually floated around a little (under and over by a couple of points) but settled on 1 each time with a solid contact at each end. 

In the end, if listening proves the tweeters are a touch soft, I can always play with alternatives to voice them to preferences. Mission are a little notorious for playing around with component values mid-run and another schematic and images of the crossover I've seen for the same model had no resistor at all and caps of wildly different values.

Cheers again.

Edited August 18 by Steever

[March Audio]

Its 0.5 ohms.  Remember that you DVM leads also have resistance.  Short them together and you will see the value.  Subtract this value from the 1 ohm you measured.  You should come close to 0.5ohms.

[The Mad Scientist]

As @March Audio said, it's a 0.5ohm. Low value resistors are labelled 3R3 for 3.3 ohm, 1R5 for 1.5 ohm etc. So R50 means  0.5 ohm. A 50 ohm resistor would be marked 50R.

 

Here's a helpful guide to values:

 

https://kiloohm.info/smd3-resistor/R50

 

If you do a lot of this sort of stuff, it's worth investing a few dollars in a decent LCR meter. LCR meters normally feature a probe compensation null, so you get a true value, which is  more accurate than measuring with a DMM.

 

It can be surprising how much component values deviate from the nominal value.

 

I build my own speakers and always match component values in crossovers as closely as possible with a meter.

Edited August 20 by The Mad Scientist

[stereo coffee]

4 hours ago, The Mad Scientist said:

 

It can be surprising how much component values deviate from the nominal value.

 

 

.... and in this application  can then change resistance value with load., Generally if you can,, doubling the rated wattage is good practice, so as to avoid temperature variations  ... but firstly check the stated resistance with a multimeter.

[The Mad Scientist]

9 hours ago, stereo coffee said:

.... and in this application  can then change resistance value with load., Generally if you can,, doubling the rated wattage is good practice, so as to avoid temperature variations  ... but firstly check the stated resistance with a multimeter.

An alternative here would be to replace the original resistor with 2 x 1 ohm resistors in parallel. Same 0.5 ohm value but now with twice the power rating.