term lab SPL meter

[got wake?]

wow, i've spent WAY too much money in the past week

here's what the termlab meter looks like in the case:

processing box, and front side of meter:

designed for SPL comp purposes only, it comes with suction cups for the windshield, and that small hole in the middle is where the metering takes place:

this is a great setup. the cables are regular USB cables, and CAT5 cables, so if i need different lengths, it's easy to change them. my only gripe is that i think it should have been made to run on 12 volts DC, so you don't need an inverter or long extension cord oh well, i'll pick up an inverter tomorrow, since i'll use it for the meter and my laptop

here's proof that a set of 8's running off 200 watts is a decent setup:

.65 cu ft box tuned to 38 hz. i burped it at 58, since that was the peak freq. 49 had a little peak to it, and i'll do some testing to see exactly where my resonant freq for my car is. the box is in the back part of the trunk facing the rear. with an audio control meter it would have been in the mid to upper 130's, since the term lab is such a stiff meter. it's usually 1 dB lower than linearX meters, which used to be the toughest. on average it's 6-7 dB's lower than a calibrated audio control meter.

i also picked up a craftsman clamp meter, that reads AC/DC voltage, AC/DC amperage, resistance, and temp. another hundred bucks to test stuff with:

not next week, but the following week i'm building a box for 4 of the TB 8's for daily driving, till i get my brahma back. i'll be running them off 1100 watts, and tuned lower in a 2 cu ft box. i'm guestimating very high 130's, and possibly low 140's out of it on the term lab

 

[servoeyes]

Hey wake...I'm having some burping issues with my install. I'm not sure if it's that the box isn't air tight, enough or what, but every once in a while I get something that sounds like a *pop* or a burp from tupperware. Any ideas?

--EDIT--

Sorry...that was wicked off topic! The burping thing just caught my attention. That's a pretty nice thing, though...how much did that run you and can you win the money back in competitions?

I wonder what my car would meter at?

 

[got wake?]

pop or burp from tupperware? i'd play some test tones to see if you can generate it on que. then play the freq that does it while you are at your box, so you'll be closer and it'll be easier to hear

total for it with shipping was $663.99. that's about half the price of the old mic style meters as far as winning the money back, depends on the comp. i would have won one that was outside ft stewart, if i had known about it. and they had a $150 prize to loudest of the day, which i could have gotten with my brahma:mad: course it was a few months ago, and i was in south carolina, not georgia as far as what you'd meter at, you can either go to a shop and find out for sure, or try this forumula someone posted on carsound, that is rather accurate for moderate systems:

Concept Basic DB Formula
-This formula is assuming that all things are perfect. It is a Logical "Guessimate" that is always within 3 db of actual!
-That voltage is near 14 volts/plenty of
battery/alternator
-Using at least 1/0 Ot guage wire
-Some kind of Line Driver is being used

1st Things first
Start off with sensitivity of the "raw" driver
Then total power of the amplifier (peak AC
volts measured with a volt meter)

For example: Take a Concept CC-D1200 amp, connected to 2 SS-12( a load of 1 ohm) You've measured the AC volts out into this speaker load as 42 volts, which calculates to 1764 "peak" watts. A/C volts squared (times itself) divided by the impedance equals power. So...42 x 42 =1764 divided by the impedance, which is 1 ohm in this instance, so its still is 1764!!! We now know the real power (cause you measured it into a real load...The Concept SS-12 woofer)

2nd Thing
Calculate the toal efficiency of the woofers
Add each woofer as +3, doubling of cone area
equals output

The concept SS-12" subs are 87 db 1W/1M (typical of all small box woofers"
Lets do the dB Log:
1 woofer = 87 dB
2 woofers = 90 dB
4 woofers = 93 dB

3rd Thing
Do the "dB log" starting with the total subwoofer(s) efficiently (which is 93 in this instance)
93 dB = 1 watt
96 dB = 2 watt
99 dB = 4 watt
102 dB = 8 watt
105 dB = 16 watt
108 dB = 32 watt
111 dB = 64 watt
114 dB = 128 watt
117 dB = 256 watt
120 dB = 512 watt
123 dB = 1024 watt
(for the example, we have 1764 watts, (comtemplate... 125 dB)
126 dB = 2048 watt

4th Thing
Add up the special "side deals" Like is the box sealed (no extra dB), hatchback or coupe? Etc.
Use the following to get "close to the REAL DEAL in SPL.
-Transfer Function (sedan) = 12 dB
-Transfer Function (hatchback with woofers aiming towards the rear glass) = 16 dB
-Sealed Box = no extra dB
-Vented box = 3 dB (UNLESS you have an odd order alignment)
-Vented box = 6-9 dB (If an odd order alignment - Big A$$ box)
-BandPass Box = 6-10 dB (depending on how small the enclosure is)
-Mic Placement = 6 dB for DB drag dash/window mic placement

Example: let's total it all up

124 dB (basic "dB log") + 12 dB (standard cab car with a direct facing woofer box) = 137
Woofer box is vented in something other than optimum or flat + 6 dB = 143 dB
+6 dB (DB drag dash/window mic placement)
So...this car will play
= 149 db (total) (+/- 3 dB)

 

[NetGuy]

I miss SPL. I used to be heavy into that about 5 years ago (back when 150 dB was considered a LOT ). Had 6 12" PG subs in a CRX that did about 148dB.

I'm kind of curious what my current setup will produce when I finally get it installed in my car. 2 a/d/s/ RS12 in a sealed box being pushed by a Zapco Studio300x (should be around 250w/sub considering they are 3ohms each). Anyone have anything similar metered?

 

[got wake?]

5 years ago i was hitting 143.2 with one 15 that was my first setup in the pro. course that was before i knew anything about ported boxes and alternate design boxes i don't know much about those subs, and i'm too lazy to look them up right now, but i'd guestimate it in the high 130's, low 140's on an audio control meter so figure low to high 130's on a term lab.

 

[servoeyes]

I think if the install is done correctly with the subs you could break 130db pretty easily with that setup, NetGuy. I don't know how to get the efficiency of my eD sub, but assuming that I'm getting about 300W and 90dB efficiency (more like 290W how I have the gain set up, I think), and factoring in the transfer function, I can pull right around 120-130db according to that equation that wake posted. If I use eD's other box design, I could pull damn near 130-140dB according to that. That's pretty cool, I'd say. I don't think that the way I did it is totally accurate, but it's still pretty impressive around 130db from a 10 powered with only 300W! Of course...I have nothing to base that off off...it just *seems* impressive to me!

Oh...and SB rules!!! Must go listen to SB sings later...

 

[got wake?]

according to winISD, with it's calculation, the efficiency would be about 84 dB. but that doesn't seem right. my brahma is about that, and it's got a much stronger motor, so it'll be a lot lower than yours. i'd guestimate it to be high 80's, and 90 is very possible.

winisd projected an SPL of 110 at 58 hz for my set of 8's i tested. course that's in an open area and 3.28 ft away. in the car i did a 130.3 and modeling it, your sub in a .5 cu ft sealed box will be about 5 dB's lower at 58 hz. and about 5.5 dB's lower at 50 hz. so guestimating your's in the 120's is probably pretty close, and that's on the term lab meter. on an audio control it'd probably be high 120's, low 130's. but there's only one way to find out

 

[servoeyes]

DAMMIT! Now you're making me want to enter in a newb class at something local...just to show them what a 10" with 300W can do!

 

[jflo]

damn audio talk ! this is something i don't understand ! hmm...the setups u guys r running...how much do u think it all weighs ? i wanna add more bump to my msp, but i don't wanna add a lotta weight. any suggestions ? this SPL thing i don't get...crazy tho

 

[servoeyes]

My setup is fairly light actually...the heaviest thing is the amps and false floor. All in all it's probably about 3 times the original MSP sub setup but I have 2 amps, a .75CF (.68 final I think)sub box, and the false floor. The floor is light, the box and sub are hefty, and the two amps are chunky. I'm not really that worried about it, though. In all it's probably about 50lbs of stuff...I'm not racing the car on a daily basis, and it really doesn't affect the pick-up noticably. Plus, I can enjoy the much better musical response now!

hey Wake...got any idea how I can find local events in my area? USACI only comes to PA and that's as close as it comes.

 

[got wake?]

servoeyes, i think most organizations aren't having comps till around march. the new product lineups are coming out, and everyone is switching over speaking of that, MB quart and RF totally revamped their lineups from what i've heard. the big RF amps are now 1 ohm stable rather than 2 you might want to call around to local shops and see if anything is going on.

jflo, you'd be supprised what a set of 8's can do i'm going to be building a setup for my friend's eclipse that he can take out for racing, but still isn't heavy for daily driving. a nice low tuned ported box with a set of 8's or a single 10 is plenty for most people. i'm making it with break away power connector, and the only other connection will be the wire coming from the rear speakers, since it'll utilize a line output converter and speaker sensor turn on. should be a pretty nice setup, but it'd run about $500 for the equipment and my time

 

[2words]

i had 2 fusion 12s a mtx 81000d in a homemade ported box and hit a 148.2 that was my best. and it took 1st in my class like 2 yrs ago. keep it loud keep me proud.

 

[NetGuy]

Yeah, I guess I should add that I was only competing in the 1-150 watt class I hit 148dB with a 2x75w PG amp.

 

[got wake?]

Yeah, I guess I should add that I was only competing in the 1-150 watt class I hit 148dB with a 2x75w PG amp.

i never liked that class system based on watts course i have one sweet cheater amp if i ever need it. an old autotek mean machine 330mxi. it's rated 165x2 at 4 ohm, but my friend benched it at over 2k watts into one ohm mono gotta love the old unregulated amps

 

[NetGuy]

I used to run a PPI ProMOS 50 (25x2, I think it was rated at), but loaded down to 1/2 ohm it was moving plenty of air. Until it caught fire (literally). Hehe...oops.

 

[got wake?]

just thought i'd add in a big happy birthday to servoeyes just noticed at the bottom of the main page that you're 23 hope you're out drinking and getting your b-day spanking from some fine lady