I just picked up a handheld analog db meter to use with pink noise for finding trouble spots in my studio. I've found that if I get it near any power source , live wire, lamp, etc.  it  pegs out making it almost useless in places like behind my studio desk. It's only a 40 dollar meter , and probably not shielded very well . I'm wondering if anyone else has seen this problem ?  or do I just have a bad meter.   Would a digital meter be the same ?  Thanks for any help .   MS..

I use an app on my smartphone.  I checked it against a meter (not sure if it was analog or digital) and it compared well.

Mrs TLW is a regulator for the UK’s Health and Safety Executive - the UK equivalent of OSHA - and sometimes needs to take accurate sound-level measurements in factories, so I’ve asked for her opinion.

For professional purposes she uses a big, very accurate, very expensive and regularly calibrated government-issue decibel meter capable of all kinds of complicated functions, producing output usable as evidence in court etc. That kind of thing is near the top of the “professional” meters.

For taking quick sample readings wherever she is without having to haul that around she uses an app called Decibel X on her iPhone. This has the necessary scales (dBA etc.) and checks out pretty well when compared to the government meter in the volume range usual at gigs and studio monitoring, if anything reading slightly high, but around the 80-95dBA area is surprisingly good.
http://skypaw.com/decibel10.html

I mostly use an inexpensive digital meter that also checks out pretty well against the government’s meter. Trouble is it was only available in the UK and the company making it have since gone bankrupt and closed, but most of the digital dB meters around can at least give a pretty consistent reading even if the numbers it produces aren’t spot-on.

The old electro-mechanical analogue meters are well past their best by now and were never that good to start with unless really expensive.

FYI, the mics in the iPhone used to have a +/-3dB tolerance at 1kHz. Then +/-2dB (iPhone 6 I think). Now-a-days the mics are +/-1dB. So take that into account when using iPhone SPL meters. Also, the mics have gotten flatter and flatter over time. Now-a-days I think they're about -3dB around 35 Hz or so and +1dB around 12kHz or so. That will also perturb the readings a bit.

If the app is calibrated for the mic frequency plot the errors will, of course, be less. No phone app is going to give spot-on measurements, but neither will inexpensive meters. Or not measuring the sound pressure level from exactly the same spot every time. Then there's the possibility of inconsistencies in the audio interface's volume control response and the possibility that unless the measurement is taken exactly where the listener's head is going to be and they never move the readings may not accurately reflect what the human hears.
 
Highly accurate and consistent measuring is complicated and expensive - and probably not needed for most real-world applications. It comes down to what is reasonably possible within the budget and room parameters.

tlw, that's my take on it - its good enough, especially for what the OP is indicating he is doing.

"Thanks" to everyone for your help and comments. I moved my power source away from "normal" problem areas and got better measurements .  MS ..