Geo Schoonmaker’s Slim LCD vs TKO On a Discovery

[melvin]

I previously ran one of Geo’s moderators against a TKO and had surprisingly similar results between the two. I had wanted to do the tests on my Discovery but it didn’t fit because of the girth of the moderator. Since then Geo created a new LCD, slim and Disco friendly.  . Let’s check it out!!

Below are some photos. Geo’s is slightly shorter which I assume has an impact on sound against the standard 6 inch TKO.

You have to run a modified dust cap just as you would with the TKO. The Benjamin air pump fit the foster adapter fine with the moderator  on the barrel.

[melvin]

I ran the test on my decimal meter and here are the results.

TKO came in at 103 DBs
Geo’s slim LCD came in at 103 DBs
Unmoderated came in at 108dbs

Below are some photos.

[melvin]

After I did the tests with the DB meter I did all the tests again with my own ears and no meter.  The reason why I did that is because I notice a sound difference between the two LCDs but I couldn’t differ the sounds very well while filming and shooting at the same time.

If you were to shoot the discovery with the TKO moderator next to me and then Geo’s slim moderator I would assume that the TKO was quieter. Even though it read the same on my DB meter. The TKO seems to have a lower more muffled sound to me. Without scientific equipment I would say they run on different frequencies of sound.

Is Geo’s backyard friendly? Absolutely. His is also less than half the price of the TKO.

This is my honest, objective review on his new design. 

-Ken

[DHWreckage]

just ordered a slim version from Geo for my 2240, cant wait to try it out!

[melvin]

just ordered a slim version from Geo for my 2240, cant wait to try it out!

After you get it let us know what you think of it.

[Rat Sniper (AKA: PaulT58)]

Is that 5db difference between unmoderated and moderated that significant? I have no idea that's why I ask...  It doesn't seem like much attenuation, or is it more of a significant change in the actual sound (frequency)?  Just curious, I've never actually measured the decibel levels of any of my LDCs, but they sure sound like there would be more of a difference than just 5db between the unmoderated sound and the moderated sound.  Interesting results for sure!

[melvin]

Is that 5db difference between unmoderated and moderated that significant? I have no idea that's why I ask...  It doesn't seem like much attenuation, or is it more of a significant change in the actual sound (frequency)?  Just curious, I've never actually measured the decibel levels of any of my LDCs, but they sure sound like there would be more of a difference than just 5db between the unmoderated sound and the moderated sound.  Interesting results for sure!

The way I understand it is that every 3 DBs the sound is doubled. So the sound has nearly been cut in half twice. Its pretty significant.

It’s more similar with the way a Richter scale works and not the way a thermometer works.

I hope this helps.

[Rat Sniper (AKA: PaulT58)]

Wow!  I had no idea, but now knowing that, I can see where it’s pretty effective. Decibels are one of those things I never really understood, like the difference between light waves and sound waves, how much slower sound travels and the difference in sound of an on coming train and one that just passed you! One of those mysteries of life I guess...  LOL!  Thank you for the great explanation.

[melvin]

Wow!  I had no idea, but now knowing that, I can see where it’s pretty effective. Decibels are one of those things I never really understood, like the difference between light waves and sound waves, how much slower sound travels and the difference in sound of an on coming train and one that just passed you! One of those mysteries of life I guess...  LOL!  Thank you for the great explanation.

Yes it can get very complicated. Haha

[mikeyb]

The perception test is a good information IMO.

I advise caution when using cell phone sound level meters. They are not designed to be accurate peak sound level meters. There is a lot of signal limiting and compression going on inside a cell phones audio system. The app makes it LOOK GOOD, but I would only use those results as a really rough ballpark estimate.

Many of the lower cost sound level meters people seem to TRUST(?) for these kinds of PEAK IMPULSE sounds are really only good for average continuous noise level readings also.

The most accurate analysis of shot noise would come from a special high dynamic range (expensive) microphone, a high bandwidth preamplifier, and a high speed A2D conversion for amplitude and spectrum analysis (FFT) in a computer.

[melvin]

The perception test is a good information IMO.

I advise caution when using cell phone sound level meters. They are not designed to be accurate peak sound level meters. There is a lot of signal limiting and compression going on inside a cell phones audio system. The app makes it LOOK GOOD, but I would only use those results as a really rough ballpark estimate.

Many of the lower cost sound level meters people seem to TRUST(?) for these kinds of PEAK IMPULSE sounds are really only good for average continuous noise level readings also.

The most accurate analysis of shot noise would come from a special high dynamic range (expensive) microphone, a high bandwidth preamplifier, and a high speed A2D conversion for amplitude and spectrum analysis (FFT) in a computer.

I definitely agree with you that this set up probably isn’t perfect. I have no clue how accurate a cell phone app could be.  However using the TKO as a baseline due to the popularity of it is a good way to compare I believe.  :/. Now I want to see what a designated DB meter would say. 

I certainly wouldn’t want to spend a ton of money but I’m not opposed to buying a meter like this and re running tests.

https://www.ebay.com/itm/Sound-Level-Meter-Digital-LCD-Display-Noise-Tester-Measurement-30-130DB-Decibel/323606215738?epid=2256179569&hash=item4b586efc3a:g:bb4AAOSwe2Zd1led

[nervoustrigger]

FYI 3dB represents a doubling of acoustic power.  We don’t perceive sound linearly however....it takes a 10dB difference for something to sound half as loud or twice as loud. 

[melvin]

FYI 3dB represents a doubling of acoustic power.  We don’t perceive sound linearly however....it takes a 10dB difference for something to sound half as loud or twice as loud.

Thank you Jason. That makes sense.

[mikeyb]

I definitely agree with you that this set up probably isn’t perfect. I have no clue how accurate a cell phone app could be.  However using the TKO as a baseline due to the popularity of it is a good way to compare I believe.  :/. Now I want to see what a designated DB meter would say. 

I certainly wouldn’t want to spend a ton of money but I’m not opposed to buying a meter like this and re running tests.

https://www.ebay.com/itm/Sound-Level-Meter-Digital-LCD-Display-Noise-Tester-Measurement-30-130DB-Decibel/323606215738?epid=2256179569&hash=item4b586efc3a:g:bb4AAOSwe2Zd1led

I think the cell phone might be more accurate than a $15 ebay item. I believe a real peak impulse noise meter runs about $500. A good acoustic data acquisition and analysis system would start about the same cost. I understand this is NOT a reasonable expense for hobby folk like us. However, a "company" that designs, measures, and sells moderators should be able to easily justify the expense for a dedicated computer analysis system to benchmark the competition and their products

[melvin]

Fair enough.