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bluewizard 05-18-2019 08:26 PM

Recommendations for New SPL Meter?
 
Went to use my Radio Shack Digital SPL Meter the other day, and it had crapped out on me. That was my trusty standby and I was counting on using it to calibrate my Smart Phone SPL App, which I haven't chosen yet. I will fiddle with the Radio Shack some more to see if I can wake it up, but I'm not holding much hope. And yes, but battery is both good and new, and the battery terminals are clean. No obvious wire breaks.

The nice thing about the Radio Shack Digital Meters is that they had a wide frequency range, and were pretty accurate for the roughly $25 they cost (years ago).

I would like a new meter in the roughly $25 range, but I'm not holding out much hope. I could perhaps ...maybe... go to approx $50.

If found this one -

VLIKE = Amazon Choice

https://www.amazon.com/VLIKE-Digital...dp/B01N2RLJ32/

https://www.amazon.com/Protmex-Porta...dp/B01F74C722/

A bit rich, but if it works, it might be OK.

There are no shortage of SPL Meters on Amazon, but the underlying question is, which one do I trust? I'm not sure.

I would like A and C weight, Fast and Slow response, and ideally, though not likely, 30hz to 10khz response. It would also be a bonus if it had Peak Hold for measuring fast impulses, though that may not be absolutely necessary.

And while we are at it, does anyone know of a good SPL App for Android? One that's not going to rob all my data, and drown me in advertising, or sell my Phone Number to every scammer in the world.

I know this gets discussed often, but I thought I would start a new thread as the market is always changing.

Steve/bluewizard

torii 05-18-2019 09:33 PM

good question. one day I used an app, ratshack meter, and umik 1 and all recorded the same 77db when I was trying to adjust audyssey.

Madmax67 05-18-2019 11:27 PM

This one was identical to the RS analog meter and looks to still be available on Amazon and the like for around 40 bucks or so.

m. zillch 05-18-2019 11:54 PM


bluewizard 05-19-2019 04:46 AM

Quote:

Originally Posted by torii (Post 58067478)
good question. one day I used an app, ratshack meter, and umik 1 and all recorded the same 77db when I was trying to adjust audyssey.

Curious what APP you were using, and when you used the UMIK-1 Microphone (I assume Microphone) what software did you use?

Steve/bluewizard

thebrieze01 05-19-2019 04:56 AM

I bought the Umik-1, and never looked back. Along with REW, it gives you so much more, that I think back of my days with my ratshack meter staring at the needle to guess the average reading, as the dark ages. It’s also individually calibrated, so should be very accurate.


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bluewizard 05-19-2019 05:01 AM

Quote:

Originally Posted by m. zillch (Post 58067690)

Thanks for that, very enlightening.

https://asa.scitation.org/pb-assets/...2857372243.jpg
The Journal of the Acoustical Society of America

Evaluation of smartphone sound measurement applications (apps) using external microphones—A follow-up study

https://asa.scitation.org/doi/full/10.1121/1.4964639

Steve/bluewizard

bluewizard 05-19-2019 05:07 AM

Quote:

Originally Posted by thebrieze01 (Post 58068048)
I bought the Umik-1, and never looked back. Along with REW, it gives you so much more, that I think back of my days with my ratshack meter staring at the needle to guess the average reading, as the dark ages. It’s also individually calibrated, so should be very accurate.

The UMik-1 I assume is a USB Mic? Do you need any other hardware to make the system work, like a mixer or whatever?

Steve/bluewizard

thebrieze01 05-19-2019 05:18 AM

Quote:

Originally Posted by bluewizard (Post 58068074)
The UMik-1 I assume is a USB Mic? Do you need any other hardware to make the system work, like a mixer or whatever?

Steve/bluewizard



Correct it’s a USB mic, connect it directly to your laptop. No drivers or other hardware needed.

REW is a free open source software (I used Windows, but I believe it works on a Mac as well) and it has direct support for the Umik-1. It will ask you to download the calibration file based on the mics serial number. Connect the laptop to your receiver/speakers and your good to go. I used the HDMI out from the laptop.

REW can be intimidating as it has a lot of functions, but the basics are actually quite simple. Just click measure - leave the default options, and view the frequency response chart. There is also a button for an SPL meter screen.


Sent from my iPhone using Tapatalk

bluewizard 05-19-2019 05:22 AM

Quote:

Originally Posted by thebrieze01 (Post 58068096)
Correct it’s a USB mic, connect it directly to your laptop...

REW can be intimidating as it has a lot of functions, but the basics are actually quite simple. Just click measure - leave the default options, and view the frequency response chart. There is also a button for an SPL meter screen.

No laptop, but my desktop computer is within sight of my Stereo system.

Curious how you calibrated the REW Software? From what I understand the Calibration File simply show how the Microphone deviated from flat across the spectrum. So, you would still need some way to set the absolute dB reading to the correct numbers. Though I speculate.

Steve/bluewizard

thebrieze01 05-19-2019 05:32 AM

Quote:

Originally Posted by bluewizard (Post 58068104)
No laptop, but my desktop computer is within sight of my Stereo system.

Curious how you calibrated the REW Software? From what I understand the Calibration File simply show how the Microphone deviated from flat across the spectrum. So, you would still need some way to set the absolute dB reading to the correct numbers. Though I speculate.

Steve/bluewizard



That’s a good question, and I don’t know the answer. It did match the levels shown on an app I used on my phone, but I don’t know how it calibrates the absolute levels


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m0j0 05-19-2019 06:22 AM

Decibel X is a decent app as well.

bluewizard 05-19-2019 08:42 AM

Quote:

Originally Posted by thebrieze01 (Post 58068134)
That’s a good question, and I don’t know the answer. It did match the levels shown on an app I used on my phone, but I don’t know how it calibrates the absolute levels

Well the price is right I guess.

steve/bluewizard

bluewizard 05-19-2019 09:07 AM

Quote:

Originally Posted by m0j0 (Post 58068264)
Decibel X is a decent app as well.

That actually looks pretty impressive for $3.99 -

https://play.google.com/store/apps/d...w.decibel10pro

Is this the one you were referring to?

Steve/Bluewizard

m0j0 05-19-2019 09:14 AM

Quote:

Originally Posted by bluewizard (Post 58068864)
That actually looks pretty impressive for $3.99 -

https://play.google.com/store/apps/d...w.decibel10pro

Is this the one you were referring to?

Steve/Bluewizard


It's pretty good, especially for just trying to get your speakers to measure the same db level using a test tone. I set my on z weighted slow, which takes a measurement every second and shows an average and peak db reading.

thebrieze01 05-19-2019 09:28 AM

Thinking about it further, the only way to calibrate an absolute level is to be able to generate a predictable reference level - which would involve additional hardware. Also most common uses are really about relative sound levels within a system (matching speaker levels, integrating a sub, measuring frequency response, decay time, phase matching etc) so accuracy to absolute levels is probably less important.

To your point, the price is right [emoji846]


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m. zillch 05-19-2019 10:05 AM

The problem with Android SPL apps is their performance will vary per model of phone. For instance it may be spot on for a specific Samsung they designed it for but terribly inaccurate for another person's HTC due to differences in the mics the phones use.

I use the NIOSH SPL app for my iphone and from what I've read the reason it is so accurate is because they know exactly what specific mic it is going to be paired with so they've designed it specifically for that mic. Apple always uses the same mic so its performance is pretty consistent from phone to phone.

Since Android companies may use different mics, per phone/brand, one solution might be to use an external calibrated mic plugged to the phone and a specific app designed to work with the calibrated mic's correction file.

Example: Dayton IMM-6 claibrated mic [under $20 at Parts Express last time I checked but it was years ago]
and Audiotool to insert the calibration file: https://sites.google.com/site/bofini...OC-Calibration


torii 05-19-2019 10:08 AM

Quote:

Originally Posted by bluewizard (Post 58068028)
Curious what APP you were using, and when you used the UMIK-1 Microphone (I assume Microphone) what software did you use?

Steve/bluewizard


the app I used was on an old iphone se....which I have replaced since then. it was a free app. I used rew with its spl

function

Madmax67 05-19-2019 11:15 AM

Quote:

Originally Posted by m. zillch (Post 58069120)
The problem with Android SPL apps is their performance will vary per model of phone. For instance it may be spot on for a specific Samsung they designed it for but terribly inaccurate for another person's HTC due to differences in the mics the phones



Since Android companies may use different mics, per phone/brand, one solution might be to use an external calibrated mic plugged to the phone and a specific app designed to work with the calibrated mic's correction file.



Example: Dayton IMM-6 claibrated mic under $20 at Parts Express last time I checked but it was years ago

and Audiotool to insert the calibration file: https://sites.google.com/site/bofini...OC-Calibration

That's pretty cool. The app is 8 bucks and the mic on Amazon is 21. Not too bad IMHO.

DonH50 05-20-2019 07:25 AM

There are absolute cal corrections for UMIK mics on the miniDSP site.

m. zillch 05-20-2019 11:22 AM

Quote:

Originally Posted by DonH50 (Post 58073018)
There are absolute cal corrections for UMIK mics on the miniDSP site.

How low and how high in frequency does it correct for?

DonH50 05-20-2019 11:47 AM

Quote:

Originally Posted by m. zillch (Post 58074230)
How low and how high in frequency does it correct for?

The level (abs reference) cal is just a single number, then there are frequency deviation corrections. I do not remember the frequency cal range, can look it up tonight (at least for the files I have). I have a vague memory that it covered 10 Hz to a little over 20 kHz, probably limited at the high end by the ADC's sampling rate. Someone who has one may be able to look; it is a text file. I checked the miniDSP site but they need a serial number I don't have with me, plus I have a cal file from CSL that extends the range and resolution a bit over the stock file. I have both files (at home, natch).

I did compare the response to my Earthworks M30 and it was very close but again not sure over what range (nor how close, have to dig up the comparison I did a few years ago). I was surprised they were that close... Meant a $100 mic and free SW (REW) could replace about $20k worth of mic, preamp, interface, and SW I had been using, a bittersweet blessing.

I would be suspicious of absolute levels since things like Windows settings can change the effective gain and such; I do not know how all that works. I rarely care about absolute levels, and tend to grab my old SPL meter like everyone else. I have not tried any of the phone apps. I had a calibrator but loaned it out years ago and never saw it again. :( I did compare absolute levels back when I got the UMIK-1, and they were close at 1 kHz, but the RS SPL meter only specs 2 or 3 dB absolute accuracy. I am too cheap to buy a certified SPL meter for the very few times I use it.

m. zillch 05-20-2019 12:07 PM

Quote:

Originally Posted by donh50 (Post 58074380)
i do not remember the frequency cal range, can look it up tonight (at least for the files i have).

Thanks in advance.

DonH50 05-20-2019 03:28 PM

Quote:

Originally Posted by m. zillch (Post 58074230)
How low and how high in frequency does it correct for?

The UMIK-1 cal file (90 deg) goes from 10.054 Hz (-5.7009 dB) to 20.016 kHz (-5.6496 dB); I noticed -3 dB points at about 12.7 Hz and 14.5 kHz but about +0.58 dB around 5 kHz. The sensitivity factor is 0.6239 dB (that is the absolute reference).

The CSL cal file goes from 4.33 Hz (-2.42 dB) to 25.01261 kHz (-48.37 dB -- clearly past the antialias filter's cutoff). CSL does not provide a sensitivity spec (they say to use the miniDSP value if we need it). The -3 dB point is around 15 kHz, not too far from miniDSP's data. I suspect miniDSP is a bit off in their low end measurements.

For comparison my reference mic, an Earthworks M30, is specified 3 Hz to 30 kHz +1/-3 dB.

I do not have the plots that overlaid the measured response; I lost that data (and a whole lot more) in a HDD crash a couple of years ago. I could recreate them but don't have the Earthworks raw data (at least that I can find on my PC). IIRC the CSL-corrected measurements virtually overlaid the Earthworks measurements from ~10 Hz to 20 kHz with a very slight deviation (<1 dB) at 5 Hz.

HTH - Don

m. zillch 05-20-2019 03:35 PM

Quote:

Originally Posted by DonH50 (Post 58075584)
The UMIK-1 cal file (90 deg) goes from 10.054 Hz (-5.7009 dB) to 20.016 kHz (-5.6496 dB);

Thanks

bluewizard 05-21-2019 04:56 PM

It tried to get the Radio Shack working again, odd thing is when I take it apart and hold the 9V battery in place it seems to work, but when I put it together and try it doesn't work again. To some extent it will work on the higher ranges, but not the lower ranges. Take it apart and hold the battery in place, and it is working again.

I guess for about $5 plus the Dayton Audio iMM-6 Calibration Mic ($16.95 Plus shipping) -

https://www.parts-express.com/dayton...droid--390-810

Is probably the best I can get for the least money. Plus, if I download other Audio Related Software, I can still use the Microphone.

I'm just not sure what software to down load.

Decibel X Pro - $3.99 -


https://play.google.com/store/apps/d...w.decibel10pro

Audio Tools - $7.99 -


https://sites.google.com/site/bofini...OC-Calibration

https://play.google.com/store/apps/d...apps.AudioTool

But there are SOOOO MANY SPL Apps to choose from -

https://play.google.com/store/search...20Meter&c=apps

And the all appear to want to take control of my Phone and all the data on it.

Audio Tools -


This app has access to:
https://lh3.googleusercontent.com/pH...zVeHiO5fkw=s20Photos/Media/Files
  • read the contents of your USB storage
  • modify or delete the contents of your USB storage

https://lh3.googleusercontent.com/aW...y-01v7ukeQ=s20Storage
  • read the contents of your USB storage
  • modify or delete the contents of your USB storage

https://lh3.googleusercontent.com/da...Jqblbu_4qg=s20Microphone
  • record audio

Other
  • change your audio settings

Decibel X Pro -


This app has access to:
https://lh3.googleusercontent.com/4r...j7aJi_G3dg=s20Location
  • precise location (GPS and network-based)

https://lh3.googleusercontent.com/pH...zVeHiO5fkw=s20Photos/Media/Files
  • read the contents of your USB storage
  • modify or delete the contents of your USB storage

https://lh3.googleusercontent.com/aW...y-01v7ukeQ=s20Storage
  • read the contents of your USB storage
  • modify or delete the contents of your USB storage

https://lh3.googleusercontent.com/xb...cLRWPNQM_c=s20Camera
  • take pictures and videos

https://lh3.googleusercontent.com/da...Jqblbu_4qg=s20Microphone
  • record audio

Other
  • receive data from Internet
  • view network connections
  • full network access
  • prevent device from sleeping


Sound like an NSA wet dream.



I'm willing to Pay for the app if I can be sure that assures me that my data/phone don't become an open book. But... which one of the Paid Programs can be trusted?

https://play.google.com/store/search...c=apps&price=2



Steve/bluewizard

m. zillch 05-21-2019 05:05 PM

Quote:

Originally Posted by bluewizard (Post 58081172)
[LEFT]It tried to get the Radio Shack working again, odd thing is when I take it apart and hold the 9V battery in place it seems to work, but when I put it together and try it doesn't work again. To some extent it will work on the higher ranges, but not the lower ranges. Take it apart and hold the battery in place, and it is working again.

Sounds like a cracked solder joint. Are you handy with (and own) a soldering gun? I'd melt and recool all the solder joints from the battery compartment all the way to where it connects to the main board.

If that still doesn't work I'd consider bypassing the entire electrical path and insert an entirely new signal path bypass wire. https://www.amazon.com/COOLOOdirect-...gateway&sr=8-7

holl_ands 05-21-2019 05:35 PM

Unless you already have a Calibrated Microphone [UMIK-1 is $91.50 on Amazon] to send signals to REW and/or TrueRTA (simpler to use), I would recommend that you "kill two birds with one stone" and look at Sound Pressure Level Meters that have A/C Switch, MAX HOLD, AND an Output port to computer running REW and/or TrueRTA (e.g. Analog OUT to LINE-IN Port and/or USB), such as is included in any of the following:
https://www.amazon.com/Professional-.../dp/B01MZ0IUGY [USB, $48 on Amazon]
https://www.amazon.com/BAFX-Products.../dp/B00P1D84N6 [Analog+USB, $57 on Amazon]
https://www.amazon.com/Extech-407730.../dp/B00OVEI06W [Analog, $117 on Amazon]

bluewizard 05-21-2019 08:16 PM

Quote:

Originally Posted by m. zillch (Post 58081208)
Sounds like a cracked solder joint. Are you handy with (and own) a soldering gun? I'd melt and recool all the solder joints from the battery compartment all the way to where it connects to the main board.

If that still doesn't work I'd consider bypassing the entire electrical path and insert an entirely new signal path bypass wire. https://www.amazon.com/COOLOOdirect-...gateway&sr=8-7

Already did that, on each battery contact there are two solder joint, I re-soldered both. Though they looked pretty good.


I think I have one of those 9v battery leads laying around, I might give that a try.

Thanks.

Steve/bluewizard

bluewizard 05-21-2019 08:29 PM

Relative to SPL Apps, I have a Samsung J7 Crown Phone which is clearly not the most expensive or up-to-date, but it is reasonably responsive considering the low price. And someone mentioned they were using an App with a considerably older and slower phone.

The problem with any App is that I have no way to be sure how accurate it is. My plan was to use the Radio Shack SPL to verify the Phone App. But that door seems to be close.

Same with REW, if it worked, I could use the Radio Shack to verify REW, so ideally I would like to have both.

Though someone mentioned the possibility of using the SPL Mic with REW. I have heard of people doing this before with Radio Shack Meters. So, that's given me a few things to think about.

There are two ways I need to use an SPL Meter.

1.) Relative dB level - that is, I don't need to know the precise level, just that this sound is consistently 10db more than that sound. A SPL App would probably be OK for this. This could also be used for taking Frequency Response sample. Again, those are not absolute, but rather only need to be considered relative to each other. In both case, it is the different between two measurement that means more than the absolute value.

2.) Absolute dB level -
Some times I really need to know how loud something is. For example, one night I was watching "The Hobbit", and my SPL peaked above 110db. That's pretty loud, and nice to know. But to make that kind of measurement, I really do need to know the Absolute Level.

I think the only workable solutions, assuming I can scrape together the money, is both a good SPL Meter (<$50), and a good SPL App (<$10) with a decent Microphone (<$20). The only drawback is - $$$$$$$$$$$$$$$$$$$$$ - not of lot of these lying around right now.

Would love REW, but the cost of external Hardware is a bit steep. My Desktop Computer is about 25 feet working distance from my Stereo System, which is a bit long for USB, and a considerable distance for Audio Signals.

And thanks to all who responded and to the general conversation that this has spawned, very educational.

Steve/bluewizard


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