Lethal

I know many competitors are hush-hush about alot of designs but:

1) Any advantage to champfering all edges inside an enclosure (ie no 90degree corners) and rounding all braces and opposite edges?

2) Sealing, Dynamat or lacquering the interior and/or exterior of an enclosure? I have seen a few competitors with non-carpeted enclosures that look like they have been varnished.

3) I have seen external flares of pvc pipe around the mouth of the port. What does this do/accomplish?

4) I have seen slot ports that are seperated in the middle and removable (baffles?). Purpose?

5) Any other techniques that may help with raising the frequency and/or improving a SPL score?

I can understand if competitors don't want to share that information publically so feel free to post or pm me if you have any suggestions.

This will be my 2nd year officially competing and I have figured out a few things.

1) Sub and port on the same surface.
2) Sub and port firing to the rear of the vehicle or in some cases firing up.
3) Finding your frequency is important. (Started the year in Surrey @ Visions DBDrag with a 133.7 and finished with a season high of 139.5 with no change in gear)Thanks Rob & Ray.
4)Placement of sub. ie How far back, angle, etc... ( I managed a season high 135.0 at Vernon AutosoundPlus DBDrag with the 02Civic. 2 JL 12W1 8ohm SVC, Phoenix Gold QX2180 90wrms!! bridged @ 4ohm in a sealed enclosure, factory battery, 4awg power, no cap, no dynamatt on a JVC KDLH3150 HU with my mother-in-law at the controls). Each run we moved the enclosure 2 inches further back towards the rear of the vehicle and each run in the lanes we increased until we were eliminated. All gear in the civic other than the HU is over 7 years old.

Last year was a great learning experience and I have to thank Rob VO [img]graemlins/bow.gif[/img] (among others) for all his help and suggestions.
Not often you would find a competitor in the same class (most of the time) offering his experience and knowledge [img]graemlins/thumb.gif[/img] . I tried to do the same all year by helping new competitors find their frequency, adjust placement of the enclosure, loaning tools and loaning them one of my DBDrag CD's. (Managed to lose 5 this year by forgetting to get them back by the end of the show) [img]graemlins/banghead.gif[/img] .

Anyways I didn't realize I carried on for so long so I appologize for the long read but I thank you in advance to anyone that responds.

Joe aka Lethal

Haunz

iTrader: (3)

I know some tricks

The best approach IMO is first find freq response of the vehicle (fv).. build a box tuned to that freq(fb)...

test find new fv with box in place... find fsystem and adjust box size/port/cone mass/whatever till you hit fv

(hint: you need a DMM, a non-inductive resistor, and a freq. counter to do this)

Do they allow amplifier output transformers in SPL competition ??

[ January 11, 2005, 02:48 PM: Message edited by: Haunz ]

Ricktc

1. In many instances yes. Test and find out.

2. Resining the enclosure often yields a gain, as well as a higher note.

3. Aeroports is what you're thinking of. Makes the transition of air in/out of the port smoother, yielding a higher score.

4. Maybe port plugs, that can be popped in and out to change from a higher tuning for SPL (IE 50 hz) to a more suitable tuning for daily driving (IE 30 hz).

5. Cut off bits of port at a time to find where your peak port length is and get the highest note possible. Bracing the box will usually bring your note up. Resining it will help usually.

Lots and lots of stuff to learn, I won't reveal every trick in the book, but it should give you a good starting point to go from.

Also;
Both are not true. Look at CRXs, or any serious competitors using trunk cars, back/up isn't always the best way to fire, and also subs/ports on the same surface is not always used.

-Rick

Rip Rock

Sometimes Resin gains ans sometimes it looses or doesn't do anything. The same goes for Dynamat. Angles in your box may help or may hurt you. This is one of the bigger must test on a mic thing. Don't go and put a whole bunch of angles in and test it either. Put one in test it. Record your voltage, spl, description of angle and location of angle. if it looses take it out. if it gains keep it in and put in another angle. record ect ect. We make shure that everything stays consistent. Making shure that your voltage was the same as the last test, making shure that the mic wasn't "touched". We wait aprox 10mins between each burp. If anything changes you could ruin your whole days worth of testing. It's easier with 2 people so one person is always watching the mic and subs. Another tip..keep a log book and record everything. One of the bigest tips is to get a meter.

Hmmm this one is a good one as well. Don't jump around on your testing!like this post [img]smile.gif[/img] Lets say you have a box that is X cubic feet. Either start from the max port area or min port area. lets say you started out with the max port area...You would then peak out that port lenght. Then decrease your port area (how much is up to how much testing you want to do [img]smile.gif[/img] ) And peak out that port lenght, keep going down and down.Keep going tell you noticed you reached your peak spl or your spl is going down hill. Go back in your notes to find your peak spl..now either build a bigger/smaller box and repeat testing or start playing with angles.
remember once you start adding angles in your box the volume decreases, re ajust your box volume then.

There is end less ways of testing and different ways of testing as well. We found(For us) that this is the most consistant way of testing and give us good results.

These are some little helpful hints to get you started. This way will take forever and a day, but you will get to know your vehical better And it will pay off in the end.

Team_Obsession

^^^ Test test and test again, keep your tests consistent. [img]graemlins/thumb.gif[/img]

Lethal

Testing is difficult. I have no mic or sensor and have zero availability to one. That is why I travelled so much last season. I went to 90% of the shows in the province for mic time. I used my qualifying round for testing and went with settings from my best results for the head-to-head rounds. If I had a run with someone I could not beat I used that run to test ie....all the shows I took 2nd to Rob VO.