Recent content by luigi57

Thank you!! Sensitivity is maximum where measured voltage is half of the generated voltage, therefore using Rsense not less than 10 times and not over 10 times the magnitude of the measured impedance is the best option I'm sure it will increase the range of measurement and it will be appreciated...

Thank you for the hint, John. Why have you limited Rsenseto 10 KOhm? When measuring transformers with high inductance (in my case 160 H) the drop-out on it is 1% of the applied signal and the resolution is limited: by increasing Rsense to 1MOhm, in example, will increase resolution. Even Rinput...

How can I set a log sweep for impedance measurement? When I make the measurements in the left side overlapping panels the text says log sweeps, but when I make export of the measurement, all frequencies have a fixed step.

True, but I don't think we are in this situation, because if I repeat several time the same measurement the result is always the same. I use a 4M lenght with one repetition and the measurement time is over 30 seconds: to check my feeling I can try to reduce the lenght in order to have, more or...

John, I'm measuring the input impedance of an audio transformer and I noticed a strange behaviour: by measuring it with different frequency ranges, the impedance and the phase are not the same values by checking them at the same frequencies: what can be the issue? I used a 10K sensing resistor...

Ok, but how is it measured the drop across the reference resistor? As difference between the voltage of the 2 channels of the audio interface or what else? In my suggested configuration the drop across the reference resistor would be measured directly with only one channel, being it...

John, I've a question on impedance measurement: is it possible to make impedance measurement by putting DUT in series configuration, instead of parallel configuration (see attachment)? I want to measure audio transformers that have a very high impedance (150H) and series configuration seems to...

John, your hint is good but it can be used only if the input impedance of the device to be measured is constant over frequency, otherwise calibration will not be of help.

Yes, I made this check and with 30mV output set for generator, the voltage at the input of the device I'm measuring is 14,4mV (-6.37 dB) and this account for the difference I find. Why are you using stimulus signal and not reference input measure of the sound card output? Sound card generator...

I made a sweep from 0 Hz to 48 KHz to get the frequency response and I checked gain at 1 KHz. Gain is defined as Vout/Vin and since Vin is connected to ref input and Vout connected to In input, I was expecting to get the result of this ratio in dB. I'm not measuring distortion at the moment...

I fully agree with you, but why in this case the difference is exactly the gain I'm measuring, while the graph shows a different value? I checked the gain with a calibrated AC millivoltmeter and it's 27.7 dB.

Hi John, I calibrated generator but I didn't calibrate RTA; after RTA calibration the gain @1 KHz increased of few dB: now the graph shows 21.2 dB, but the difference during measurement in reference and headroom is 27.7 dB, same difference I read as difference between IN and REF IN in Levels...

I'm using REW 5.31.3 on WIN11 and I'm measuring the frequency response of a preamp; on the SPL graph I read a 7 dB gain (V/V), but the difference in the level between reference and input is more than 20 dB: why the graph show this 13 dB difference? It seems that the graph use the output signal...

Thank you for the hint, Tim!

Why impedance measurement graph higher value is limited to 1KOhm? I'm measuring an MC step-up transformer and by scrolling cursor impedance maximum is more than 16KOhm, Is there a way to increase the maximum Y axis value in order to see the complete curve on the graph? In the left hand...