The Great 15" Challenge

[bumpin buick 5,000+ posts]

You're seriously painting these test boxes...?
nG

Well I have them built perfectly, sealed up air tight, and smooth as a whistle. I have no use for the boxes and one of the builders said he could use them again so why not make them look presentable.

I have a three stall paint booth and shelves of Dupont Chromobase. I also have nothing to do this weekend, I figured why not go all out while I am bored all weekend.

 

[ngsm13 5,000+ posts]

Lol... werd.

nG

 

[adio 5,000+ posts]

Hey....You are a FCKING DUMBASS. If you are going to do your job...lead by example. Stop whinning like a little *****. This is the reason why this forum has turn into shit. Too bad you dont actually act like this in real life, you'd get put into your place right away.
OP..just move this entire project onto a different forum. Mods on here need to grow the fck up.

ahaahahahhha, u started off with a 'hey'.//content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif

 

[adio 5,000+ posts]

i only read a few pages here........ i see drama now as i did with the 'great 12 challenge'

 

[bumpin buick 5,000+ posts]

Just an update on whats changed:

Equipment:

Agilent MSO6052A 2+16 CH Mixed Signal O-scope

EMU 4141USB sound card

FLUKE OF-500-10 OptiFiber Multimode

2 USB (freshly calibrated) TL mics

Boxes:

All 1.5" thick (double 3/4"MDF)

2.5^3 @ 35hz

3.5^3 @ 35hz

4.5^3 @ 35hz

2.5^3 @ 40hz

3.5^3 @ 40hz

4.5^3 @ 40hz

2.5^3 @ 45hz

3.5^3 @ 45hz

4.5^3 @ 45hz

Test:

Using the EMU with ARTA software and O-scope I will be able to set each amp (during nominal load) to within about 5 watts of each subs RATED POWER. From there I will perform multiple burp tests with a wide range of frequencies, everything will be graphed on RTA termlab and the O-scope ARTA software.

The bassrace runs will be held using a variety of three songs, Late-night tip/B*tches/Lollipop. Each song has its own range of frequencies that will help give a "good idea" as to which subwoofers perform better for 30 seconds at a set volume. This is obviously a much less accurate test then tones but it is still something I feel is useful to viewers.

The first weeks test will be held in a Toyota 4runner, with dual mechman alternators and literally pallets of batteries from a sponsoring shop that is a stinger dealer, they hold no connections with any companies involved mind you. Testing will begin with all rated powers being run, then I will continue to increase in 100-500wrms increments for each sub. I will be not be using any thermal probs that could cause any damage to any equipment as I know some companies have questioned that.

Second weeks test will be held in a controlled facility called Alcan Industries, where I have access to a 2,000 cubic foot controlled temperature and humidity room, used in the past as a curing room for poly-propelyne film. Each box will be placed in the center of the room on a three foot high stool with the TL on a mic stand roughly three feet off the ground. Room temperature will be set at 70 degrees Fahrenheit along with a 50% humidity.

I have worked to get the controls very set, all though they are not very realistic to consumers. I have built this experiment on the recommendations from Mark from Mach 5, Steve from RD, Jacob from Sundown, Scott from Evo, Nick from FI, and a Dbdrag world final judge, which will be most likely be present during the test (Jeremy Weber).

 

[adio 5,000+ posts]

Just an update on whats changed:
Equipment:

Agilent MSO6052A 2+16 CH Mixed Signal O-scope

EMU 4141USB sound card

FLUKE OF-500-10 OptiFiber Multimode

2 USB (freshly calibrated) TL mics

Boxes:

All 1.5" thick (double 3/4"MDF)

2.5^3 @ 35hz

3.5^3 @ 35hz

4.5^3 @ 35hz

2.5^3 @ 40hz

3.5^3 @ 40hz

4.5^3 @ 40hz

2.5^3 @ 45hz

3.5^3 @ 45hz

4.5^3 @ 45hz

Test:

Using the EMU with ARTA software and O-scope I will be able to set each amp (during nominal load) to within about 5 watts of each subs RATED POWER. From there I will perform multiple burp tests with a wide range of frequencies, everything will be graphed on RTA termlab and the O-scope ARTA software.

The bassrace runs will be held using a variety of three songs, Late-night tip/B*tches/Lollipop. Each song has its own range of frequencies that will help give a "good idea" as to which subwoofers perform better for 30 seconds at a set volume. This is obviously a much less accurate test then tones but it is still something I feel is useful to viewers.

very!! nobody drives around listening to tones ans sweeps all day

 

[John_E_Janowitz 10+ year member]

I hope you didn't find my comments offensive before as I only wanted to help better your testing. I think you are definitely going in the right direction with this now. Especially the testing in the room there. The only thing I would suggest with that is to have the cabinet on the ground with mic also laid on the ground. The reason is because you get the first reflection off the floor that will cause ripples in the curve based on the time difference the sound takes to go from box to floor to mic. If you only plan to measure to 80-100hz this may not be an issue. The larger this distance, the lower in frequency it effects the response though so making the reflection occur quickly is much better for subwoofer measurement. With the mic on the floor you'll be able to measure accurately up to the 1/2 wavelength of the microphone diameter. I can get to around 5KHz or higher with the mic I have using a ground plane measurement. You'll then be only limited by the distance to ceiling and back down or walls to mic. Putting the cabinet in the corner optimizes the room as the reflections occur right away and only affect the higher response. Here is an example of measurements done in this ground plane style by Mark Seaton for the AV123 HR UFW-12 with our driver in it.

http://www.av123forum.com/showthread.php?p=672192#post672192

In any case, I'd be willing to put in an AV15H into the mix. Let me know what impedance you're interested in. We're just up in GB so you'd be welcome to come up and get the quick tour of the shop, or I could run one down to you. Let me know.

Also I didn't see in the latest post, but for the vented boxes at 35, 40, 45hz, where are you setting the highpass filter?

John

 

[James Bang 5,000+ posts]

so how will this test help companies grow?

 

[terra 5,000+ posts]

so how will this test help companies grow?

//content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

 

[bumpin buick 5,000+ posts]

I hope you didn't find my comments offensive before as I only wanted to help better your testing. I think you are definitely going in the right direction with this now. Especially the testing in the room there. The only thing I would suggest with that is to have the cabinet on the ground with mic also laid on the ground. The reason is because you get the first reflection off the floor that will cause ripples in the curve based on the time difference the sound takes to go from box to floor to mic. If you only plan to measure to 80-100hz this may not be an issue. The larger this distance, the lower in frequency it effects the response though so making the reflection occur quickly is much better for subwoofer measurement. With the mic on the floor you'll be able to measure accurately up to the 1/2 wavelength of the microphone diameter. I can get to around 5KHz or higher with the mic I have using a ground plane measurement. You'll then be only limited by the distance to ceiling and back down or walls to mic. Putting the cabinet in the corner optimizes the room as the reflections occur right away and only affect the higher response. Here is an example of measurements done in this ground plane style by Mark Seaton for the AV123 HR UFW-12 with our driver in it.
http://www.av123forum.com/showthread.php?p=672192#post672192

In any case, I'd be willing to put in an AV15H into the mix. Let me know what impedance you're interested in. We're just up in GB so you'd be welcome to come up and get the quick tour of the shop, or I could run one down to you. Let me know.

Also I didn't see in the latest post, but for the vented boxes at 35, 40, 45hz, where are you setting the highpass filter?

John

Thanks you got PM also I dont have anything set in stone for the highpass filter, any recommendations are more then appreciated

 

[darsum 10+ year member]

(just curious), what probably will be the distance between the TL mic and the subs?

 

[bumpin buick 5,000+ posts]

(just curious), what probably will be the distance between the TL mic and the subs?

not exact on the measurements yet as they are still undecided, I was figuring three feet. Mark of Mach5 suggested that I have it resonably close, but I dont recall what "close" meant.

Also I am unsure if I will have it on the ground or elevated as I have to company owners telling me different ways. I have a feeling it will be pretty accurate with either, maybe I will end up doing both.

 

[mrogowski 5,000+ posts]

You don't want any reflections reaching the microphone. This is why I suggested to do your tests in an open area.

 

[bball09124 10+ year member]

You don't want any reflections reaching the microphone. This is why I suggested to do your tests in an open area.

That kinda screws with having the temperature/humidity the same for every test though. If each box is tested in the same location, with recommendations from Mr. Janowitz included, will reflections really be a problem?

 

[mrogowski 5,000+ posts]

Not really. If you are able to do run the tests on the same day in the same environment, then you have a level playing field.

I did not read the response from John before posting - his statement about laying things on the floor is interesting to say the least. I have never done that but I am always open to new and different methods, *especially* if they work //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif