db meter

[Chuck_Finley]

I'm needing one in the 145-180 range and they all start at 500.

For comparison (and depending on how close you are)....

165db - space shuttle launching
170db - Saturn V launching
180db - levels of some volcano eruptions

[jluv]

What?

[FunFordCobra]

It's honestly not a true SPL build. It's a daily music player ground pounder tuned very low and tight. There's a 4000w sundown amp on them down to .5 ohm. From what sundown is telling me, it's putting out around 5000w if it keeps 13.5v, which it does. I haven't clamped it yet and I don't know box rise but rise is minimal because of the smaller port. So, I don't know my true wattage at my tuning yet. It's just been together a few weeks and the subs just now on the verge of being broke in and bugs worked out. I did go way over RMS which is only 1500. From what I've seen these will take 4k rms, dangerously..

To answer your question I didn't use any graphs.. I've just been getting cut sheets from sundown. I don't have the time to fail a box right now and I'm way too inexperienced to start drawing up my own specs. My last system that I just I tore out burped a 148 back in 2006 at 40hz but it sounded like shit for music. This one is much louder so that's why I believe I'm tappin low 150db (not TC meter either) and wanted to see before I start the wall this winter. I don't plan on hitting 160db, ever..

I'm looking at SPL lab but like I said they start at 500. The indash I want is 800.. I haven't seen a cheap alternative besides TC meters and they are known to measure less accuratly than SPL labs by a few dB sometimes in the 15x.x range. TC also starts at 400.. Guess you pay to play.

[Z06killinsbf]

What frequency is that tuned to? Easier to hit the big DB's at a higher freq. If you're 150-154db at 20Hz, you're the man.

[Mach1]

I found a 33-2055 for $25 that I am trying to snag.

[FunFordCobra]

It's at 30hz. Yea I really wanted a shaker not an spl rig. It's just going to happen to have a good spl around 35hz or so. The sheet for spl port was tuned to 45hz, the shaker 30hz. Port dimensions were larger too for the spl sheet.

[8mpg]

what are you using it for?

[Mach1]

reviewing speakers

[8mpg]

reviewing speakers

How about using a calibrated mic? Its more expensive but you will get better measurements and can graph it nicely. Umik-1 is a very popular microphone people use for home theater.

[jluv]

What frequency is that tuned to? Easier to hit the big DB's at a higher freq. If you're 150-154db at 20Hz, you're the man.

That's pretty much unheard of, right? Even the competitive SPL guys aren't burping that low, are they?

I hit 146.8 at a show with just 1000 watts on two 15s many years ago in my Explorer, and it wasn't set up for SPL at all. The box was tuned to around 33hz, but the peak output was around 55 hz, for whatever reason. Again, it was in no way an SPL setup. It's been louder since then (more power), but I've never had it metered since that day.

[FunFordCobra]

That realm is only walked upon among guys that drive speaker boxes on wheels lol. We're talking 150 inches of combined cone area and 20k Watts at least to get a 150+ 28hz burp in abig ass vehicle like mine, or The Jesus of box builders.. Small cars can get away with alot less. These are drivable cars BTW.

Getting from 146-150 is a big jump. 150-155 is even harder and so on if I remember right. Like as the loudness has to double? Could be wrong. I believe world record is 182.4db although.

[FunFordCobra]

Met this guy about 6 months ago, the owner Scott Bowman. He does big numbers low and does not compete with about 20k watts. people do 30k-40kwatts and don't hit near his numbers on low notes.

This is him tapping out a few popular bass head youtubers whom also have 20k-30k watt systems.

[jluv]

That realm is only walked upon among guys that drive speaker boxes on wheels lol. We're talking 150 inches of combined cone area and 20k Watts at least to get a 150+ 28hz burp in abig ass vehicle like mine, or The Jesus of box builders.. Small cars can get away with alot less. These are drivable cars BTW.

Getting from 146-150 is a big jump. 150-155 is even harder and so on if I remember right. Like as the loudness has to double? Could be wrong. I believe world record is 182.4db although.

The rule of thumb I've always heard is you have to double power to increase 3 db. I'm sure it's not an exact science. Those guys doing 165+ are doing concrete doors and panels and steel braces everywhere, right? Insane. I'm much more of a SQ guy these days, but I still like it loud.

[LS1Goat]

Do you use the logging versions of these to map frequency response?

No. The RS meter (mentioned above) as the mic, plugged into my Behringer U-Control, using REW to graph response. I use a calibration file for the RS meter that gets loaded into REW. You can find them on the Home Theater Shack Downloads area of the Calibration forum.

I found a 33-2055 for $25 that I am trying to snag.

And get yourself a good flexible Tri pod.

reviewing speakers

This is a graph I made using the above set up to measure room response with a dual sub arrangement, in an untreated room that has a horrible 58-60Hz null. Mic'd at primary listening position.

Left sub only - corner loaded (Purple), Right sub only (Green), Dual subs (Red). No smoothing applied. Ignore the inductance hump.



Measuring phase alignment

[FunFordCobra]

The rule of thumb I've always heard is you have to double power to increase 3 db. I'm sure it's not an exact science. Those guys doing 165+ are doing concrete doors and panels and steel braces everywhere, right? Insane. I'm much more of a SQ guy these days, but I still like it loud.

Yea man. Those guys tune to their vehicles natural low frequency resonance. They are basically speaker boxes with a motor to run the alt. Some don't even have alts or motors and they run all 16+v batteries, like 30.. I'm sure the 170+ range can stop your heart.