Stupid language barrier. By time sampling you mean how often it gathers the info?

Your RTA won't truly be an octave analyzer like it claims. Instead it will synthesize the 1/nth octaves from an FFT. The FFT is done based on a sampling amount of time. Changing this time will change your results. So will changing the resolution of the FFT. You can't have both frequency resolution and amplitude resolution in the same FFT as one or the other will compromise the other. Needless to say this makes results less than consistent.

Add to that a mic that has a non realistic response and a sound field that will not let you be consistent (change the space, change the potential standing waves) and you don't really stand a rats chance in hell in knowing whether or not it improved your score. If it is only to ear you care about, then use your ear.

Measurement mics are not cheap. The one I have is nearly $2k although you can get by much cheaper. The cheaper ones will be reasonably accurate to within a dB or so. Mine is 0.1dB.

Environment will vary a shitload though as will the effect of the processing you use.

I eventually may end up with the Russian SPL meter(TermLabs alternative). But it is way in the back of my list.

 

Environment sure does play a big roll. Just slightly opening my window makes it louder.

 

It may be easier to not use the on-board mic. A wired one for easier maneuver may do the trick as well.

Tons of problems with wired ones as well. There is a reason that the TL does not use one. Only two mics made in the world that can actually measure SPL vehicles in operation with accuracy and they start around $6k. Made by Bruel & Kjaer.

I will have to test and see, if there is a gain. I don't want to know what dB's I am hitting, just if it there is a change if I tinker with stuff.

It's basically free to measure, so why not.

As I said, the louder one may show up quieter on that mic.

Well, that's what I get with cheap equipment.

 

In the end I hope for some gain. Everyone is running POS boxes made out of particle board and the overrated Ground Zero. I want to spank some asses.

Oh, and btw the TL sensor does not measure sound pressure accurately or linearly either. It is repeatable though which is the only reason it can be used for judging comps.

Measurement mics are not cheap. The one I have is nearly $2k although you can get by much cheaper. The cheaper ones will be reasonably accurate to within a dB or so. Mine is 0.1dB.

Environment will vary a shitload though as will the effect of the processing you use.

I bet you sold my budy the $20k mic he brought home and we sat around measuring stuff with.

It's not that much about the actual score rather than a particular change made and it's effect on the score, it being lowered or improved. I like the idea of knowing if I do a certain upgrade(brace the box better, add fiberglass, bigger port flares) how that interacts with the score.

 

But then I'll need a real testing setup.

We measured the dog barking.

Tried to measure farts.

Measured his GF yelling at him.... that one sounded waaaaaaaaay louder than the machine told us.

We measured bear cans fizzing. And some other shit too.

It looked like the most incredibly cheep Matel big button kids toy. Came in a box with 3-5 inches of foam around it to protect it. LoL.

It's not that much about the actual score rather than a particular change made and it's effect on the score, it being lowered or improved. I like the idea of knowing if I do a certain upgrade(brace the box better, add fiberglass, bigger port flares) how that interacts with the score.

But then I'll need a real testing setup.

Sean said a lot of smart guy stuff. Boiling it down, do you plan on competitions or just shits and giggles? If it is just fof fun, don't sweat it.

The other thing is that nothing about the mic really matters for your application other than it can handle the SPL without shitting the bed, and that it consistently reads the same dB at the same dB. It doesn't have to be accurate and correct or delicate but it must be consistent.

You forgot linear or at least approximating it Matt.

Another foreseeable problem is having a consistent control. Temperature and voltage differences will affect the reading for spl, and they can likely yield greater differences than the variable being tested.

I think measuring will be done at a lower volume, so the mic won't 'shit the bed'.

 

I plan on going to a competition, yes. But it is far from my goal and the car is not set for any of it. I just want a bit more that is all.

Another foreseeable problem is having a consistent control. Temperature and voltage differences will affect the reading for spl, and they can likely yield greater differences than the variable being tested.

I'll not be measuring at full tilt. Neither the voltage nor the temperature of the equipment should change dramatically.

I think measuring will be done at a lower volume, so the mic won't 'shit the bed'.

 

I plan on going to a competition, yes. But it is far from my goal and the car is not set for any of it. I just want a bit more that is all.

Won't matter what the level. The mic you have won't work if you change other variables. Well it could, but it is also likely it won't.

Oh, and btw the TL sensor does not measure sound pressure accurately or linearly either. It is repeatable though which is the only reason it can be used for judging comps.

 

Repeatability is it's strong point. Although at some point I saw fluctuations in the TL which I did not see on my meter, while keeping the "same" input between measurements. 

Another foreseeable problem is having a consistent control. Temperature and voltage differences will affect the reading for spl, and they can likely yield greater differences than the variable being tested.

 

Honestly, in days when the sun is not blaring, I would get results within 0.2dB, full-tilt measurements, at most 5 minutes between measurements. One of my most efficient projects was loudest first burp after the car sat overnight. All others it would be almost 0.5 under.  

It's not that much about the actual score rather than a particular change made and it's effect on the score, it being lowered or improved. I like the idea of knowing if I do a certain upgrade(brace the box better, add fiberglass, bigger port flares) how that interacts with the score.

 

But then I'll need a real testing setup.

 

One weird thing that a customer did was to use dash silicone on the port and inside the box. He left my place with 146.8 dB, did a bit of sanding, made the inside of the flares flush with the pipe, silicone'd everything inside and did 147.8 at a competition. 

weather

Aargh.

Windows 8 handsfree telephony thing won't control my phone. No option. Works fine in Windows 7. Pissing me off!

And no, I don't need it "now" but if I am going to go Win8 in the car I will.

Unified Remote ftw btw. No longer need to carry a slide projector indexer. Pointer would be nice, but oh well.

Can you see what's actually on the screen of the controlled unit or it just a remote.

Just an "air mouse"

Well, I went for a test drive with the new springs. Apart from a rebound clip hitting the sway bar (fixed the clip with a BFH), it's very good in the bumps. 

It sits like shit, arched upward on the front side and straight on the rear side but I never bottomed out today. I've never driven it so fast on bumps, with the old springs the rear would bottom out  at much slower speeds. 

 

I talked to the guy who made the springs, another leaf has to be made and it's either going to replace one existing leaf or an addition. My suspicion is that stepping sucks, that's why the front side is arched inwards and there is a gap between 2 leafs on the rear side. Another leaf would bring my spring rate up, it feels slightly softer than the front spring rate now. 

 

Drums are going away to a magical land called scrap pile

I can't wait to have a functional handbrake again. 

I've got that too.

Your is probably Wi-Fi tho, mine has not that big of a range with the Bluetooth.