Hi there,
I recently bought about 12 resistors of the Jantzen audio superes resistors for an experimental crossover I built. I was very surprised to find that pretty much all of them are 8-12% off when I measured them (e.g. a 3.9 Ohm resistor measured 4.3 Ohms). Stated tolerance is 1%.
I am using an Amprobe 38XR-A, which I believe is a decent multimeter. Battery is fairly fresh, and measuring capacitors and inductors revealed very close tolerances.
To measure, I simply put the multimeter into resistor mode and connect the leads of it to the leads of the resistors.
Maybe there is something I don't understand? Or did I just get a bad batch? I had the impression that Jantzen is a respectable brand, given the fact that Troels Gravensen is using their products pretty much exclusively...
Any hints would be greatly appreciated!
I recently bought about 12 resistors of the Jantzen audio superes resistors for an experimental crossover I built. I was very surprised to find that pretty much all of them are 8-12% off when I measured them (e.g. a 3.9 Ohm resistor measured 4.3 Ohms). Stated tolerance is 1%.
I am using an Amprobe 38XR-A, which I believe is a decent multimeter. Battery is fairly fresh, and measuring capacitors and inductors revealed very close tolerances.
To measure, I simply put the multimeter into resistor mode and connect the leads of it to the leads of the resistors.
Maybe there is something I don't understand? Or did I just get a bad batch? I had the impression that Jantzen is a respectable brand, given the fact that Troels Gravensen is using their products pretty much exclusively...
Any hints would be greatly appreciated!
3-4 ohms is quite a low value to measure with a multimeter so firstly make sure the meter reads zero with the probes clipped together. That the resistor leads are clean and the probes clipped on tightly. Just holding them can give false readings. I have oily skin and touching the probes can give me odd readings. Not such a problem with higher resistances.
Also, check some other resistors such as metal films that have a fairly low tolerance (if you have any) to see if they also vary in the same direction and magnitude. Assuming the lead error isn't the issue, of course.
Yes he does. I am sure he has big kick backs from promoting their products.
I would not worry about resistors, considering your speakers impedance changes anywhere between 3 ohm and 200 ohm.
Use Kelvin measurement, aka "4-wire measurement". 0.5 Ohm (additional resistance being shown) seems very reasonable for standard cables.
So a standard multimeter is only "good enough" from like 50 Ohms upward (that would be 1% error, aka "good enough").
Also be aware to not touch the probes, that can result in major measurement errors on large resistors (not so much on small resistors, though).
So a standard multimeter is only "good enough" from like 50 Ohms upward (that would be 1% error, aka "good enough").
Also be aware to not touch the probes, that can result in major measurement errors on large resistors (not so much on small resistors, though).
If you have a lab supply, you could put a known voltage to the resistor and , measure the drop, the use Ohms law, but it seems strange, be sure your test leads are in working order, very low resistance, even if wiggled, be sure the resistor leads are clean , and not corroded, if test leads are crocodile, the spring must apply a firm grip.
His lowest range is 1000 Ohms and the accuracy there is +/- 0.5% of the reading + 8 digits. So you need to add 8 least digits to the (possible) error.
This is normal with digital meters and often overlooked. 0.5% seems impressive. But here this is 0.8 Ohms on top of the 0.5%.
This is normal with digital meters and often overlooked. 0.5% seems impressive. But here this is 0.8 Ohms on top of the 0.5%.
Thank you for all the great responses.
I now first tested the resistance of the multimeter by just connecting the leads (without clips). I am getting 0.1 - 0.2 Ohms resistance. But strangely that is not always the case... after turning it off and back on, I sometimes get values in the 3-6 Ohm range!
Measuring the same resistor, and then turning the multimeter off and on, and measuring again, also gives me quite inconsistent readings.
So I must assume my meter isn't quite ideal for measuring these low resistances... and I should trust the manufacturer's numbers... or try another method of measuring as some of you mentioned above.
Measuring some much higher value resistors (another brand though) seemed to work much better by the way. 10k, 100k, all measured very within 1% tolerance.
I now first tested the resistance of the multimeter by just connecting the leads (without clips). I am getting 0.1 - 0.2 Ohms resistance. But strangely that is not always the case... after turning it off and back on, I sometimes get values in the 3-6 Ohm range!
Measuring the same resistor, and then turning the multimeter off and on, and measuring again, also gives me quite inconsistent readings.
So I must assume my meter isn't quite ideal for measuring these low resistances... and I should trust the manufacturer's numbers... or try another method of measuring as some of you mentioned above.
Measuring some much higher value resistors (another brand though) seemed to work much better by the way. 10k, 100k, all measured very within 1% tolerance.
You could try a new battery and cleaning both end of the leads but as you have discovered until you get consistent results with the probes together you won't get the answers you are looking for. You could try and find a resistor of higher value, say 80-100 ohm that does measure consistently with your meter, note the value and then add a new resistor in series. The values might might be more consistent and at least indicate your new stock is within range.
OK, I discovered a "feature" that seems quite useful: The REL button. If I put the multimeter in resistance mode, connect both leads, and press that button, it will basically subtract the existing resistance from the next result (it measures relative to the resistance of the lead resistance).
It also seems to help if I turn off auto-range, and set it to the lowest range possible.
Using these two methods I am getting a lot closer to the values specified.
It also seems to help if I turn off auto-range, and set it to the lowest range possible.
Using these two methods I am getting a lot closer to the values specified.
Connect two resistors in parallel. If your resistors are of true value and you are measuring with proper technique, the value should be half the resistor value. If you are making a procedural mistake, I expect your higher than anticipated value will remain in the same neighborhood.
You can try gathering some resistors, whose value you trust, wire them in series with the mystery resistors. Use your favorite voltage source. Measure output voltage source, with your two series resistors as a load. Measure voltage drops across each resistor. Appy a little ohms law might give you some insight about what is going on.
You can try gathering some resistors, whose value you trust, wire them in series with the mystery resistors. Use your favorite voltage source. Measure output voltage source, with your two series resistors as a load. Measure voltage drops across each resistor. Appy a little ohms law might give you some insight about what is going on.
Not a great option for low value resistors, unfortunately. In fact, even worse than directly measuring the resistor - the error introduced by cabling/multimeter is twice as high.
Using the REL feature is probably the best you will get. That meter isn't that good even though it probably was expensive.
For low value of resistance, you need to use a "Kelvin" (4 wire) connection. Normally bench meters are the only things capable. Note also the high frequency response isn't very good. Keysight, Fluke handheld meters can high a frequency range of up to 100 KHz. The bench equivalents 300 KHz. Accuracies (basic DC) of 0.05%. My old HP 974A has this, as does my new Keysight handheld meters.
See if you can pick up a used, good HP 34401A, or maybe a 3457A. These meters hold calibration well and are worth every penny. PLus, you can compare readings with your amprobe to get an idea how its readings compare to reality. That makes your Amprobe more useful.
For low value of resistance, you need to use a "Kelvin" (4 wire) connection. Normally bench meters are the only things capable. Note also the high frequency response isn't very good. Keysight, Fluke handheld meters can high a frequency range of up to 100 KHz. The bench equivalents 300 KHz. Accuracies (basic DC) of 0.05%. My old HP 974A has this, as does my new Keysight handheld meters.
See if you can pick up a used, good HP 34401A, or maybe a 3457A. These meters hold calibration well and are worth every penny. PLus, you can compare readings with your amprobe to get an idea how its readings compare to reality. That makes your Amprobe more useful.