Dual channel multimeter or another option?

[bdunham7]

Best your read the V1.5.2R1 release notes again. Sure there's a small bug in the time region setting but it can be worked around with a UTC setting or I have a beta without that bug.

Isn't it mostly bug fixes from 1.3.9R10 that I don't have in 1.3.9R6?  I upgrade slowly and let other people deal with bleeding-edge bricks!

Probe check is a nice feature, but not bleeding-edge.  My ancient and primitive TPS2024B has it...

[tautech]

Best your read the V1.5.2R1 release notes again. Sure there's a small bug in the time region setting but it can be worked around with a UTC setting or I have a beta without that bug.

Isn't it mostly bug fixes from 1.3.9R10 that I don't have in 1.3.9R6?  I upgrade slowly and let other people deal with bleeding-edge bricks!

Probe check is a nice feature, but not bleeding-edge.  My ancient and primitive TPS2024B has it...

Try it with some different probes and it should autoset the attenuation.

[thared33]

The holidays got in the way but I'm back and still in need of a 2-channel multimeter.

I already have an analog oscilloscope, a fluke MM and a cheap Amazon multimeter. While a DSO is tempting, I was looking for a handheld DMM since they're much smaller and less cumbersome. The Prova 903 looks perfect for my needs but I was hoping there would be an older, used 2-channel model on eBay for under $150 or so.

I'm also in need of a function generator but I'll post another thread about that once I figure out a solution for a 2-channel DMM and just use my computer for a generator in the meantime.

[Swake]

What you want to compare the amplitude of 2 audio output signals, right? And the more these signals are the same in amplitude the happier you are, right? So actually what you want to make visible is the difference between the 2 signals. The bigger it is the more you have to compensate.

Does your scope has 2 channels? If yes it certainly has a substract feature (Inverse + Add is the same). Feed the 2 outputs of the tape device to the 2 channels of the scope and select the substract feature you have a visual that will show you amplitude difference. It will also show you any phase shift between the channels.

Tell us what model scope you have and we can help you out configuring it.

[Swake]

w2aew made a video about this feature on the scope, second half:

[807]

Do you need to measure absolute values, or do you need to just align the left & right channels? You say in your first post that you align and calibrate. I assume that because you are using an audio interface connected to your computer, that absolute values aren't that important?

Can you explain a bit more how you do this. Do you have a test tape with a tone recorded on it. Or do you just play whatever is on the tape?

If it's purely for L & R alignment, then perhaps something as simple as a cheap LED VU module might be OK for your requirement?

[BeBuLamar]

  Fluke model 45.  I don't know if they still make them or not but they've been around a while and I'm sure you can find one on E-Greed. Like most Fluke meters, it's a very good meter and not a hunk of junk.

https://www.tequipment.net/Fluke45.html#description

The Fluke 45 doesn't work for what the OP wanted. It can measure 2 things at the same time like voltage and frequency. It can also measure current and voltage (by switching back and forth between the 2 functions automatically) but it can't measure 2 voltages at the same time.

[HKJ]

One way to balance tow signals is to feed them the same input signal and then connect a DMM between the two hot output terminals.
Adjust until minimum on DMM and they balance.
If the adjustment is two separate pots, then first adjust one to the correct level, then connect the meter between the outputs and adjust the other to minimum on the DMM.

[thared33]

The oscilloscope subtract trick is cool, but it would be more beneficial to see voltages. I both need to balance L/R channels and also keep an eye on input/output levels.

Seeing two channels at the same time is a thing of convenience. It isn't that I can't do what i need with a single channel multimeter, it's just easier and faster with a dual channel one. Actually, I could just keep using my computer for everything and not worry about this at all; but a 2-channel DMM is MUCH easier to move around than a computer/audio interface or a DSO (or a big millivoltmeter). Basically, I need a big dumb portable millivoltmeter that fits into my hands. A 2-channel DMM fits this perfectly.

Can you guys recommend something like the Prova 903, but older/cheaper/used?

[BeBuLamar]

 You want some thing like the Leader LMV 186A. I don't see any modern version of the meter.
https://www.ebay.com/itm/374371542600

[tautech]

The oscilloscope subtract trick is cool, but it would be more beneficial to see voltages. I both need to balance L/R channels and also keep an eye on input/output levels.

You can engage measurement in scopes in case you weren't aware. Statistics on them too.

[BeBuLamar]

When I need to do something like the OP does I tried to use 2 DMM (same model) but found it's quite difficult. Using a 2 channel scope is much easier.

[Swake]

If cheap and small is an absolute criteria then go for two Aneng 8001 zip tied on a piece of cardboard to keep them together. 13€ a piece including shipping, it's not going to be cheaper than that.

Of course doing measurements on the cheap always gives cheap results and has limits that you'll have to take into consideration. Same with using tools that aren't made to measure the things you're measuring. OK, a multimeter can measure voltages but in your case you'll have to be happy with a frequency range of a few hundred hertz maximum, and certainly in this price range, forget that multimeter thing. That is not usable to 'calibrate' an audio output interface.

Better buy a decent audio measurement app on a refurbished android phone with a cheap sound card on the USB and use that thing.