Z1NONLY

iTrader: (2)

Every piece of test equipment can be calibrated differently. It's been years, but I seem to remember the need for different settings on the meter we used when we switched mics for SPL vs RTA.

Using the wrong settings could really jack up the numbers. Regardless, if my setup was reading x when other similar setups were reading less than x on the same equipment, my setup had more output. Mic plaecment makes a massive difference too. (they were using a template when mine was measured.)

138.x was the lowest reading that car/system ever had. 139.8 was the highest.


I miss those current-hungry beasts.

My LT Won

audio control used a mic, the termlab is a pressure sensor. yes the audio control mics do have a dial that can change your numbers but that is not what i meant. you seem to be very out of touch with todays audio. sounds like you need to do some brushing up on your stuff.

also 138 is not loud what so ever. not even on todays stricter meters. the average mainstream brand junk coming out of local shops in prefab boxes will do high 130's.

go sit in something loud.

Z1NONLY

iTrader: (2)

You meant my numbers were inflated. I know. I'm telling you that without knowledge of the calibration of the equipment that metered my system, the fact that Termlab uses a pressure sensor is irrelevant. The system(s) could have been adjusted to create low-ball numbers just as they could have been adjusted to inflate the numbers. The fact that my system was consistently louder than other comparable systems when metered on the same systems is, however, relevant.



And it seems that you just got here. Your use of catch phrases and truisms without any apparent understanding of the underlying fundamentals is telling.

You're like a car audio "See N Say" that just keeps getting its string pulled.

Just because power is more plentiful and cheaper than ever, doesn't change what loud is. 138db is enough to break the plastic latches on the cheap rear windows on the Sentra twice, just from air pressure. 138db, at certain frequencies, is also enough to make vision blurry, and put enough pressure on your ear canal to feel it in your adam's apple. 138db is enough to transfer kick drum impacts through the car and into the pavement enough to feel through tennis shoes when standing next to the car. (works particularly well when coupled close to a solid structure.)

If your assumption of 138db can't do that, then maybe the test equipment that you have been exposed to needs calibration.

Been there, done that. I have probably forgotten more 150db+ systems than you have sat in.

Bullitt5339

This thread has went way past being productive.

My LT Won

you sir are a joke. 138db has zero affects to my vision, breathing,ear drums. hell my z meters in the upper 140's on music and has none of those affects on me. this is also done on stock electrical and subs seeing less then half there rms rating. the speakers are hardly moving yet. luckily my 250amp alt will be here soon. so .5ohm on my 3500 should push me right near the 150mark that will be on a termlab as well.

my other project car will do over 150 no problem. i will be starting on that at the end of this month.

i have a few friends doing over 150 on music. i hear those setups rather often. these are also termlab numbers.

the termlab doesn't have controls like the old a/c mics where you can inflate numbers. atleast that i am aware of. may be possible to do in the software?

here is a little info for you to read on a pressure sensor vs a mic.


CONDUCTIVE ENERGY - Competition vehicles these days are loud. Really loud. When a competitor "burps" their system, everything inside of the vehicle vibrates. This includes traditional mic stands and the newer, custom made mic holders that attach to the windshield. This vibration adversely affects the accuracy of the measurement system because the mechanical energy from the vibration is coupled to the microphone diaphragm. To understand why this takes place, you need to think back to what you learned in high school physics. One of Newton's laws states that, "an object at rest tends to remain at rest". Newton is obviously referring to an object which has mass. Microphones use a diaphragm which has a small, but significant mass. As the mic stand vibrates, the microphone housing vibrates and this, in turn, causes the mic capsule to move "around" the diaphragm. This induced energy produces errors in the SPL reading.

You can verify this yourself. Take a microphone and measure the SPL of a paint shaker. Next, clamp your microphone to the paint shaker and turn it on. You will see a significant difference in readings. Next, try the same test on a Term-LAB system. You will notice that the Term-LAB readings are not significantly affected. This is because Term-LAB doesn't really have any moving parts. (It uses an integrated strain-gauge on the substrate of a silicon die.)

TEMPERATURE - Microphone diaphragms are significantly affected by temperature. I don't know if any of you play the drums, but I can tell you from experience that when a drum head gets cold, it gets very tight. When it gets warm, it gets loose. This is because temperature affects the tension of the drum head. Tension variations of the mic diaphragm will adversely affect SPL measurements.

Term-LAB has integrated temperature compensation. Large temperature variations will not significantly effect the reading of a Term-LAB system.

HANGOVER - Whenever a loud vehicle is measured with a microphone, the microphone diaphragm is altered in some way. Although I do not have the ability to determine why this is the case, I do have a hypothesis. Mic diaphragms must be very, very light in order to minimize their mass. This results in a very thin membrane material. I believe that exposure to high SPL's actually distorts or "stretches" the diaphragm.

You can try this yourself. Use a pistonphone calibrator to calibrate your microphone. Put the mic in a loud vehicle and then "burp" it. Next, immediately place the mic back in the calibrator and test it again. You will notice that the reading is off by as much as 10 dB. Continue to check the calibration every minute. After 6-8 minutes, the mic should read "close" to what it was originally calibrated for. In most cases, it won't be what it was when you first calibrated the mic. And, in many instances, it can be off by several dB.

Term-LAB doesn't require any calibration. In addition, you can burp it repeatedly and it will produce the same reading. (The sensor in Term-LAB is rated for SPL's in excess of 200 dB although the sensor assembly is currently configured for SPL's to 183 dB.)

IMPACT - Microphones are easily damaged if you drop them or bang them against something hard.

You can try this yourself. Drop your mic. On second thought, DON'T drop your mic or you may ruin it. You can drop your Term-LAB Sensor if you like. In fact, kick it across the floor. Throw it against the wall. It will read exactly the same. Actually, kicking the sensor across the floor doesn't subject the unit to near as much stress as attaching it to the windshield of a vehicle. Imagine the windshield moving back and forth 1/2 inch 60 times a second! That is some SERIOUS G-Force. The Sensor PCB is conformal coated. It's like encapsulating the board in an epoxy resin. This prevents fractures in the electrical connections due to vibration and stress. This is the same process that is used to protect the PCB's in military aircraft.

LINEARITY - Microphones are non-linear. In fact, they are inherently non-linear. This is because the mic capsule acts like a spring. (Imagine the excursion on a woofer.) Have you ever pulled a bow (as in bow & arrow)? You will notice that it takes more and more effort to pull the bow string the farther you pull it from its resting position. Mic diaphragms and woofers suffer from the same problem. In fact, microphone non-linearities were one of the biggest problems experienced in sound-off competitions. You could take 2 mics and calibrate them together. Next, you could put them in the same car and measure that car at different SPL's. Guess what? The readings were always different. This is because no matter how hard we tried to match up microphones, they always had different linearity characteristics.

Term-LAB sensors are perfectly linear. In fact, the linearity error of the sensor is less than 0.1% over the entire measurement range! The typical linearity error is less than 0.01% over the entire measurement range.

AIRFLOW - Microphones can be adversely affected by airflow. If you direct a stream of air (like that from a port) onto the mic’s diaphragm, it will greatly affect the measurement.

Term-LAB is not significantly affected by airflow. Try it yourself. Take an air hose and blow air onto a microphone. Notice the effect the airflow has on the measurement. Next, do the same thing on a Term-LAB sensor. You won't see an appreciable change in the reading.

SYMMETRY - Microphones produce a non-symmetrical output waveform at high SPL's. In fact, the "negative" portion of the waveform becomes less and less sinusoidal in nature as SPL increases. (Imagine sound as pressure variations in the standard atmospheric pressure of 14.7 PSI. There is infinite room for positive pressure changes but negative pressure changes cannot go below an absolute vacuum.)

Test it yourself. Connect a scope to the line output of your SPL meter. Play your system at high levels. You will see that the negative side of the waveform is not symmetrical with respect to the positive side of the waveform. Next, do the same thing on a Term-LAB system. Notice that the waveform is perfectly symmetrical.

Z1NONLY

iTrader: (2)

Great cut and paste.

You really have the "See N Say" bit down.

2bad240

iTrader: (6)

i have been following this thread, he is a one upper and will argue anything he can.
i know a little about car audio and have probably built at least 20 different boxes for myself in the past 10 years. no math no software just looking at what i have to work with and figuring out what will work. for some people thats not good enough, but they have all sounded good and performed the job i built them to do.

your box looks good and does the job you built it to do.

i have thought about once i hit the 11.5x mark upgrading the audio in my z but i have other goals to worry about first.

Z1NONLY

iTrader: (2)

Just dusted off the old Radio Shack SPL meter and took some readings with the meter in my hand in the general vicinity of my head (sitting in the driver's seat). As I suspected, it's over the meter's 126 db range on the C-weighted scale. (With music)

A 50Hz test tone was making ~106db on the A weighted scale.

And before you comment won, please take a moment to google the different weighting curves.

The 10wx/120w is doing quite well.

Z1NONLY

iTrader: (2)

11.5!

My LT Won

Radio shack meter? You are a funny guy. Those hand helds are junk and prove nothing. I watched my buddy max one of those out with his mids and high. It was rather funny.

I love how you ignore my post and pull the "see N say" line again. I have plenty of real world experience. I would love to link this thread to a real car audio enthuiest website so they can share the comedy with me.

Z1NONLY

iTrader: (2)

That's right a Radio Shack meter. I was going to run out and buy a meter that costs more than my amp, sub, and box combined, just to meter it for you, but then I found my old Radio Shack meter........

Ignore your post? You went into a rant about a 150db project car, then posted a big cut and paste from termpro's website promoting their meter.

I'm sure it's a great meter, but you responded to my "See N Say" point with... a "See N Say" post.

I'm 100% sure there are people out there who are better with car audio than I am. In fact, I have worked with a few of them.

You however, just aren't one of those people.

You obviously love car audio enough to invest time and effort into your own systems. You even appear to have received good advice from knowledgeable people. But you really need to take the time to understand the underlying concepts behind the good advice others have given you.

I thought by now you would have already posted my perimeters in a car audio forum and come back with an alternative design to my own. -Maybe one that increased output at the expense of the response curve, thinner wood for more airspace with bracing or something.

Anything.

But no. You instead persist on trying to convince me that the system I can go in my garage and listen to (which you have never heard) doesn't sound as good as it does. Or that I have never heard loud systems, or that systems metered with the new meter render every system I have ever heard somehow "not loud" (comparing 150db systems in a thread about a single 10wx?). Or that my port can't possibly work because it doesn't fit the template you have been given. Or that any meter other than the Termlab is grossly inaccurate.

On and on and on.

The bottom line is you called my design "awful" yet two pages later, still don't have a better idea.

[Yoda] More experience, you need. [/Yoda]

My LT Won

Your radio shack meter proves absolutely nothing. The fact you even brought it up is a joke.

Well if you have been around these knowledgeable people maybe youshould have taken it as an oppurtunity to learn something. I also like how you keep reffering to everything I say as something I have been told. Yes some and a lot of other things from real world testing.

Well in your case I would have added 45s in all the corners. Also rounded all the edges on your port inside and out. Bracing or a double baffle wouldn't help in your case. I would however increase port
area, also an increase in box size can yeild more output and help low end. That is within reason. Helps box be more efficient. Also I would. Fire the sub. Up port up off the glass. Your box has nothing to load off of in its current position. Now some of this wont be ideal dor you since I'm sure u wanna save space since your box location and speaker choice size. That's why I felt no need to offer up on a new design I would however do some research and look into better equipment. Jl is over priced and leaves much to be desired. Step away from the big box store brands.

My LT Won

i do have some experience with port area being to small. my gf had a local shop build her a enclosure for her 2 sundown sa8s because she didn't wanna wait for me too do it. these were in a 1.2 cubic foot box tuned to 35hz. the system sounded ok at about 1/4 volume, once you started turning up the volume the subs got real muddy and output didn't increase. they were being choked. i couldn't hear any noticable port noise just the lack of output at higher volumes and very sloppy muddy bass. long story short i built the same size box and tuning using a 4' aero port this time and output and sq was improved 100% sounded like a totaly differen't setup. i tend to use nothing less then 15" of port per cube on my loud daily systems. lots of port area does however yield a more peaky response around the tuning frequency (which is fine with me)

Z1NONLY

iTrader: (2)

The fact that you think there's only one meter one the planet than can read the SPL from my single 10 shows a lack of understanding. It's like telling people they can't measure voltage from an outlet with anything other than a true rms Fluke.

You have hitherto shown no understanding of the reasons behind your generalities.

A 45 for one turn seems a little overkill. Particularly when you conseder the fact that the port displacement was already cannibalizing my greatly limited net volume.

I already flared the inlet and outlet of the port without making the effective port length too small.

No kidding? We have already gone over this....

And that's before the massive port's overall area is subtracted from the net internal box volume...creating an ugly-sounding hump in the response curve of a now much smaller net-volume box.

This is the first suggestion you have made that *could be helpful in this application. I could have built a slightly more complicated box and added an inch or so to the top debth (front to back) to allow for a top mount 10". However, experiments with my sealed enclusure when I originally installed it showed that it wasn't worth the added complication or the added risk with the "come and get me" nature of putting the sub on display for anyone looking in my back window. (Particularly if/when I upgrade to a nicer sub.)

Not a usless suggestion, just a different cost/benefit view.

That, and weight. (Although I already compromised on that by going to a slightly larger box than the sealed.)

The WX was pretty cheap @ $70. I would be glad to entertain any other brands/models that also provide T/S specs.

Bullitt5339

I would recommend different subwoofers for you, except the companies that I represent don't make anything that would perform up to par given your power level. To be honest, given your power level, any decent brand name subwoofer that is around 150-200 watts rms is going to be fine, your present subwoofer included.

You can spend plenty on subwoofers, I have one that costs over $2000 sitting in my office right now, but unless you want to run 3000+ watts rms to it, it's overkill for 99.9% of situations. I think you did a pretty good job matching up subwoofer to amp power, even if I'm not a fan of JL. That's just an opinion or a preference, and everyone has their own brand loyalties, me included. I'm very biased towards Sundown Audio and Incriminator Audio for SPL or SQL setups and Stereo Integrity for the more SQ side of the house for subwoofers. Tons of people love JL, and that's their choice, just like I have mine. Hell, most people don't even realize that the best subwoofers on earth even exist because they're not sold in box stores or most local car audio shops.

One thing that I think isn't being kept in perspective is the rms wattage you're providing the subwoofer vs. the subwoofer itself. I don't see any problems running you current setup from a power available perspective, and nothing I offer is going to be a night and day difference in your situation, and in fact will be more expensive and require more power to get the benefit. I also believe that JL is operating on technology from 10 years ago for subwoofers, but if you're spending $70-100 on a subwoofer, how much technology are you really getting in the first place? It's all about perspective. You're running a low wattage, small enclosure setup and I'm sure along with that, you didn't expect to rattle windows and experience pain every time the bass hit, which is perfectly fine.

It's all about keeping things in perspective. Not everyone is trying to get the loudest thing on the planet and spend $400-600 each on subwoofers and run 3000 watts rms. If you're happy with the setup for the amount of money invested, I'm happy for you and wish you the best. If you ever decide to increase power or quality of equipment over time, I'd be happy to help you out with your decision and box design. Unfortunately, I'm not the best at compromise. If I am given a space to work in that just won't support the proposed subwoofer size or quantity, my first recommendation is to step down in one of those areas in order to get the optimal alignment for your given music type and goals, which is where I would have went in your situation. Given your space available and goals, I probably would have went a completely different direction that you did, but that's just me. You decided to work with the space you had available and the equipment you had available and compromise to end up with something that is pleasing to your ear, and I see nothing wrong with that no matter what I would have done differently.

Z1NONLY

iTrader: (2)

Bullit, (or anyone else that might know) might I find T/S numbers on an SA-10?

I just got a used 500/1, and I'm exploring my options.

Bullitt5339

Here's the T&S for the dual 4 ohm Sundown Audio SA-10

FS : 31.6 Hz
Qts : 0.45
Qes : 0.49
Qms : 5.64
VAS : 21.9 L
Mms : 187.4 g

If anyone here ever needs complete specs on any Sundown Audio equipment, I either have them all, or can get them fairly quickly. Having the owner's cell phone number on speed dial helps a lot. If you were in my area, I could get you one for a good price, but I'm not really allowed to sell them outside of my local area because there are dealers in that area.

I do not mind helping anyone out with the company's equipment, since I'm a rep, and if anyone's in southern NC/ northern SC, I can actually provide equipment and pricing for you. My build will be a pair of SA-8's on a Sundown SAX-1200D on the subwoofer side.

Z1NONLY

iTrader: (2)

That makes a flatter response curve than the W3 I am looking at and even extends a little lower in the same box, but it's not quite as sensitive.


What is the mounting depth and overall outer diameter of the sub?

What do you use for a grill?

Bullitt5339

Mounting depth = 6"
Cut out is 9 3/16"
10 3/8" OD with gasket

For a basic ported enclosure, I would suggest
1.25 - 1.5 cubic feet tuned to 30 - 35 Hz which yields an F3 in the mid to high 20s range.

Unfortunately sensitivity is a product of power handling. As a subwoofer gets beefier to handle more power, the sensitivity is going to go down. While the rated RMS rating is 600 watts on the SA-10, in reality with clean power and a smart user, it can handle quite a bit more than that. Those ratings that Sundown gives the subs considers the idiot factor into them. The guy that's going to play it at distortion for 10 minutes on low voltage at high THD. On 600 watts of clean power, you can play that sub all day with no problems.

Bullitt5339

Oh, forgot about the grill. Because of the XMax of these subwoofers, most standard grilles will not clear the woofer at full excursion. While most people go without a grille, the only grille type I can recommend at this time is a bar type, something like this:

http://www.google.com/products/catal...ed=0CDwQ8wIwAQ