Frequency Response

[Richard Crowley]

Are there any general-purpose meters with AC voltage frequency response across the traditional audio range (20 Hz ~ 20 KHz)?  Or do we just assume that kind of performance is the purview of specialty audio test gear?
Either hand-held or bench meters, and flatness within perhaps 0.2dB?

The few times I have seen it mentioned, it seems like most meters barely made it up to 1KHz (if that).

Perhaps this is an arcane requirement since these days, anybody can use a computer sound card and software to conduct an automated frequency response test faster than you can just do a single measurement on a meter.

[HKJ]

High-end multimeters usual goes about 50kHz.
That is meters like Fluke 289, Hioki DT4282, Brymen 869s

[BravoV]

Just few examples at AC volt true RMS spec :

Fluke 287/289 -> @100 KHz accuracy -> 3.5% + 40 count at (20 KHz  to 100 KHz) , while lower freq has better accuracy.

Keysight/Agilent U1252B or U1253B -> @100 KHz accuracy -> 3.5% + 120 count at (15 kHz~100 KHz ), same as above, lower freq has better accuracy

[PTR_1275]

Would some think like the Keithley 2015 do?

It has the built in source and THD measurements that can be great for testing audio equipment.

[billfernandez]

Not a multimeter, but high performance at a reasonable cost ($450), and lots of audio frequency range test and measurement capability:  the QuantAsylum 401.  https://quantasylum.com/products/qa401-audio-analyzer   

[1anX]

Not a multimeter, but high performance at a reasonable cost ($450), and lots of audio frequency range test and measurement capability:  the QuantAsylum 401.  https://quantasylum.com/products/qa401-audio-analyzer   

Impressive performance!

[bd139]

Look out for old Fluke 8050 bench meters. They are usually dirt cheap. They are flat to 100KHz easily and will give you relative readings in dB relative including reference impedance.

Also GW Instek GDM-8341 does it as well.

I’ve got a Heathkit IM-5238 analogue unit that’s good to 500KHz on the bench.

My Keysight U1241C is also flat to 50KHz although it only quotes 2Khz in the specs.

[Gyro]

Oldies but Goldies...

Datron 1041 / 1051 bench multimeters, True RMS, Option 01:

100mV - 1kV ranges:

40Hz - 5kHz: +/- 0.03% Rdg +/- 0.01% FS
5kHz - 20kHz: +/- 0.06% Rdg +/- 0.02% FS
20kHz - 100kHz: +/- 0.1% Rdg +/- 0.05% FS

10mV Range @ >300uV:

40Hz - 5kHz: +/- 0.1% Rdg +/- 0.05% FS
5kHz - 20kHz: +/- 0.2% Rdg +/- 0.05% FS

Impressive for the day (and today?) especially on the 4 1/2 digit 1041.

[rstofer]

Analog Discovery 2?  It uses a 14 bit ADC for the scope inputs and those same inputs are used for the Voltmeter gadget.  Bandwidth around 30 MHz.

https://reference.digilentinc.com/reference/instrumentation/analog-discovery-2/reference-manual?redirect=1

I don't think I have ever seen a specification sheet like those provided for DMMs.

[nctnico]

Are there any general-purpose meters with AC voltage frequency response across the traditional audio range (20 Hz ~ 20 KHz)?  Or do we just assume that kind of performance is the purview of specialty audio test gear?
Either hand-held or bench meters, and flatness within perhaps 0.2dB?

The VC8145 has decent specs for true-RMS measurements (0.8% +50 digits) but you have to adhere to some limitations where it comes to the amplitude because it uses a log-lin converter.

[Andreas]

Hello,

I would use my scope for true RMS measurement.
(many digital scopes have it nowadays).
AC-Linearity in 100mV range is better than a HP34401A DMM.

My scope even has a frequency generator which can be used as tracking generator for frequency response analysis.

with best regards

Andreas

[nctnico]

Even at DC an oscilloscope has an accuracy in the 1.5% to 3% range which make an oscilloscope useless for accurate amplitude measurements (unless you have ways to calibrate it and control drift).

[2N3055]

Even at DC an oscilloscope has an accuracy in the 1.5% to 3% range which make an oscilloscope useless for accurate amplitude measurements (unless you have ways to calibrate it and control drift).

Hi res Picos are 1% at DC (my ancient 212/100 is 1%) and PicoScope 4262 is 0,25% to 1% depending of range.
But DC accuracy is not so important here, but linearity. Also it is a relative measurement when using Pico FRA software.

But I think Andreas is referring to a fact that because of TrueRMS converter used in HP34401A, there is a dead band around +5mV/0/-5mV  where measurements are not even defined and are highly non-linear. With 20mV signal you might get 10-20% error...

http://www.gellerlabs.com/34401A%20AC%20zero.htm

New  34465/70 has direct sampling (TrueVolt AC) and are superior (within frequency response range of, course)

But I realized that, for instance,  my Pico 212/100 gives better results in true RMS  than old school thermal RMS meters, and has 50MHz bandwidth...
I use it for noise measurements.
Regards,

Sinisa