Buying a meter

[shizzzon 461]

Ok, i thought i had tested enough as to how exactly i am going to build and face my box but maybe i'm wrong so i'm going to buy this meter -

http://cgi.ebay.com/186-db-SPL-SOUND-LEVEL...1QQcmdZViewItem

They say that it is calibrated just like some other top of the lines including the new Termlab sensors.

I would buy a TL but not for the price they want for just building the best box for my money.

All you do with this thing is hook it up to a DMM and the voltage it outputs, you look at this chart to see your Db reading. It is accurate down to 1\1000th of a volt AND Db so that's interesting. The slightest change can be detected which is great.

So, here in the near future, i'm going to build a new test box with multi changeable ports on each wall so i can find out which way in every possible direction is the loudest.

[Mark LaFountain 1,054]

let us know how that works. They do a good job "selling" them on the web site with their descriptions, lol

[shizzzon 461]

oh, i'm not the kind of guy that buys cheap equipment whatsoever.

Everything i own in terms of electronics is expensive. I don't like entry to average level anything.

$1000 head unit

$1000 sound deadening

over $8k worth of computers in house.... get me?

Of course i've been broken into before too. More than twice within 8 years. However, insurance is there for a reason.

I did about 45 minutes of researching just to make sure that the mic they have on ebay is the same one on the companies website and was studying everything about it.

Only thing i'm not for sure is how to recalibrate it if necessary. However, i'm mainly only going to be using this for a day or 2 then i'll be ready to build my enclosure.

Of course i'll still use it after the enclosure for curiosity but if it starts to get inaccurate, i don't care. As long as the first 2 days are consistent, i'm fine.

[///M5 2,833]

<--skeptical

[Guest zedman]

I am skeptical as well. I just dont see it doing what they say it will do.

[shizzzon 461]

Well, the thing retails for $249 but they got it on here for practically nothing.

It's not as convenient on the Tlab sensor which i'm sure makes the cost go down but if you have an o-scope, which i do, it will give me the actual db reading on screen.

Supposedly its gonna take forever before i get it but everyone's feedback says that they like it.

Watch, week after i get it, i'm gonna come on here and say i did a 157 with 1 10 off the head unit and claim it's accurate! Well, we'll see in a couple weeks.

[jonbearsmt 919]

i once seen tha chit aswell..... it reminds me of the HORSPOWER PLUG IN BOX.....

you know the one you buy on ebay and it tells to slice it into your MAS sensor and all it does it make you check engine light come on!... and if you open the box it its have a simple resistor.

[shizzzon 461]

I know what you're referring to but the good news is somewhere on their site, they guarantee that no check engine light will come on with this thing! Haha.

they claim competitors have used these up to 170db for years.

They also claim that they are calibrated just like TLabs and other high end meters are that i've never heard of.

I'm not trying to compare this meter to a hgih end meter. All i need it to do is read louder when i do something right and get lower when i dont. That shouldnt be hard.

I could have just gotten a radioshack mic but they dont go high enough for car audio.

[jonbearsmt 919]

I know what you're referring to but the good news is somewhere on their site, they guarantee that no check engine light will come on with this thing! Haha.

they claim competitors have used these up to 170db for years.

They also claim that they are calibrated just like TLabs and other high end meters are that i've never heard of.

I'm not trying to compare this meter to a hgih end meter. All i need it to do is read louder when i do something right and get lower when i dont. That shouldnt be hard.

I could have just gotten a radioshack mic but they dont go high enough for car audio.

same problem i had... i looked around.. and the only ones i could find peak out at like 135 Db... chit ......... i know im louder then that!

did you buy it yet?????/ keep me updated.

[JimJ 11]

Since the biggest variable in determining SPL is the environment, I don't see how voltage has any shred of anything to do with it...it doesn't even make sense on a theoretical level.

[shizzzon 461]

yea i did 1 minute after i posted this thread. The guy\company said it take 5-9 business days AFTER payment has cleared before item is shipped. And since i live the furthest shipping distance possible from California, i'm expecting it to be here by no later than.... Nov 4, 2009, no cancel that, hehe.

Should be here by no later than march 20th, hopefully...

[shizzzon 461]

Since the biggest variable in determining SPL is the environment, I don't see how voltage has any shred of anything to do with it...it doesn't even make sense on a theoretical level.

Exactly what i thought... but when they have comparisons with a Tlab sensor being less than 0.2db off in many cases, it makes me wonder exactly is in that little box and what is it doing...

I'm sure they would never say how it works or else their business is exposed but if it works, hey i dont care if i had to hold headphones in my hand and hook em up to a humidifier that must be placed inside the car... if it's accurate enough, it's accurate enough...

[johnecon2001 82]

I call BS. If it worked.. everyone would be using it.

[shizzzon 461]

Well, while we have non believers, hehe, i just got done reading a 19 page thread over on www.caraudio.com about this thing. After going through all the posts of people calling each other names, hehe, i got to some results!

The results-

This meter's accuracy is DEPENDENT upon the quality of your DMM. Now, i have 2 meters and an o-scope. I'll probably use the o-scope anyway but it says it is dependent because the entire time you wish to use a DMM, it must be able to read millivolts and be accurate. The voltage reading need not be moving before testing begins as an example. I own a triplett DMM and have never had a problem with it.

Results vs TLab PRO -

This cheapo meter was reading LOWER than a Tlab in ALL frequencies. Wha ha ha, i win.... no, but seriously, that's what this chart shows over in this thread.

He did state this-

TLab PRo's sensor give a Db reading by averaging 3 different frequencies into 1 score. This meter just measures Db based upon the single loudest note. Also, in his testing, by the time he reached the Fs of his car, this meter and the Tlab Pro sensor were near exact Db reading, interesting....

So anyways, apparently this meter is good.

The instructions it comes with they say are completely retarded but does come with a cd that helps a lot.

It took this one guy 23 days to get his once he ordered it so it's gonna be a while for me i'm sure.

[jonbearsmt 919]

damn,.... i kinda wann a buy one now.... i donno if i can wait........ chit 21 days... i donnnoooo..... i think im gonna wait

[JimJ 11]

How does it actually work, though?

Voltage does not equal SPL...in no way, shape, or form. Doesn't matter how accurate the DMM is. If I take Woofer A with Amplifier A out of whatever install it's in and put it in another, I'm likely to get an entirely different reading, even if I've got the same level of power down to however many digits of precision you want.

Measuring pressure is the key here...how is this meter doing that?

[NB50 206]

How does it actually work, though?

Voltage does not equal SPL...in no way, shape, or form. Doesn't matter how accurate the DMM is. If I take Woofer A with Amplifier A out of whatever install it's in and put it in another, I'm likely to get an entirely different reading, even if I've got the same level of power down to however many digits of precision you want.

Measuring pressure is the key here...how is this meter doing that?

I would also be interested in knowing how it works. My first guess would be a piece of piezoelectric material in the receiver that would create pressure into electricity. The only problem I'm having is how the frequency plays in as I believe piezoelectric material has a high fs, Not sure if it can be changed though.

[shizzzon 461]

They never say on their site, maybe it does on the disc... who knows.

But however it does, this chart i seen, it was only extremely accurate with a Tlab when they were both measuring the peak frequency in the car so the way this meter measures pressure is different of coure but also a lot stricter which results in lower Db levels than tlab sensor. It's consistency for measuring 1 frequency to the next may be too strict?

the meter does matter to a certain degree.

Gotta have one that measures millivolts.

2nd, he said once you start reading up in the 140db range, anything higher then that, a cheaper DMM "shouldnt" have a problem getting somewhat accurate enough in the Db output. He says this because after about 140db, the millivolt ratings start to spread out more, meaning you need more millivolts just to gain 1 Db so a slight innaccuracy in the meter wont affect your score much if any.

[mrray13 30]

<--skeptical

i want to hear more on why you're skeptical. seeing how this thing plays in your area of expertise (measuring stuff), it'll be interesting to see what your real thoughts are.

i know you think the TL is a joke, to a degree. (well, i can't remember your exact thoughts) so tell us why you think this would, or wouldn't, work.

and maybe when shizzon gets this thing in, he'll send it up to you to play with. compare it to that high end shitz you work with everyday. i know i'm bringing my TL this summer, lol.

wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee

[///M5 2,833]

Well it doesn't say shit about the technology therefore it is a joke. Tell me what it is: a pressure transducer, an electret mic, or whatever the hell.

The real joke is they say they compare with B&K. My friggin' ass, that comment alone makes it obvious that the thing is a scam. A B&K analyzer and microphone to measure 185dB would cost on the order of $30,000+ and would easily be a couple orders of magnitude more accurate.

[dem beats 1,223]

Well it doesn't say chit about the technology therefore it is a joke. Tell me what it is: a pressure transducer, an electret mic, or whatever the hell.

The real joke is they say they compare with B&K. My friggin' ass, that comment alone makes it obvious that the thing is a scam. A B&K analyzer and microphone to measure 185dB would cost on the order of $30,000+ and would easily be a couple orders of magnitude more accurate.

One of my good friends brought a meter like that home from his work so he could become familiar with it. We had planned on testing my HT and doing some tests... this was all before I moved into an apt... anyway. Those high end meters are insane. I nearly had kittens there when he told me the 30k price tag and multiple thousand dollar different mic set ups. Well I guess when its your job you need that equipment, I was just happy to play with it and see the difference of a real aneoch chamber and really how loud the quietest room in your house was.

All in all I know verry little about how these things work but I know one thing for an absolute fact. If the tech was as accurate as they say and in anyway at all reliable companies wouldn't throw hundreds of K at the other unit when they could just buy 50 of these disposable priced ones for their needs.

[///M5 2,833]

When I worked for B&K I never lost an order to stuff like this even at 100x the price. It was very easy to prove that the cheap gear was priced as such for a reason.

[shizzzon 461]

Well,again, u guys know I didn't buy it to compare to a TL or something more, I just got it to know if what I do helps or not to get the most out of my daily setup.

I have nothing to compare this mic too so don't expect me to.

[JimJ 11]

so the way this meter measures pressure

Does it? If it's measuring pressure, then where does the voltage reading come into play, or how does it need to?

I'm still shaking my head at the theory behind this, if any...just because it's comparable to a TL for certain readings really means squat, LORAN-C was comparable to GPS in accuracy if you were comparing two known coordinate points, but as soon as you went to a random point on a map the accuracy went out the window. Repeatable accuracy with new values is what's important here, and I'm not getting how they're coming up with a number.

These questions aren't directed at you, more in general...until I read otherwise this one is going in the file with power cords that improve the sound stage and supports that get the interconnects off the floor.

[///M5 2,833]

And if you think Jim feels that way from his post, imagine it x10 and that is how I feel.