posted
I've had an on going issue in my car for the past 3 months. The score had dropped off by 1.6db's overall. I looked all over the car for the reason that the score had left. I checked everything from electrical, enclosure, roof braces, you name it I checked it.
I recently changed from 2 12's to 2 15's. My last score that I did with the 12's was a 148.1 and I had origionally done a 149.7 with them to start. It was pretty unexplainable why the score just dropped off. I changed out the front battery in my car to a larger more capable one. At this time I also went to 2 15's. My score then went from the 148.1 with the 12's to a 149.7 with the 15's. This tells me that my 1.6 db's is still missing.
The other day I found that on my hatch door (I have a Focus ZX3) there are two little rubber stopper type things. They were unscrewed quite a bit and sticking out about 3/4 of an inch more than they were supposed to. It appeared to keep my hatch from making an air tight seal. I screwed them back in all the way and imediately saw that the hatch could close more than it did before. I decided to play some music and I could tell a difference right away. Now I don't know if it is me being optimistic or not but I think that's where my score had dropped off at.
Does anyone out there think that it could cost me 1.6 db's by my hatch not making a good seal? The ports fire right into the hatch about where the seal is and the woofers are firing up in the car. I have yet to get it back on the meter since discovering this, but I'm hoping to do at least a 151 if that was the culpret.
-------------------- TEAM SUNDOWN AUDIO 2009 NSPL Car 1801-3600 Watt Record Holder: 151.2db 2009 NSPL Car 3601-Up Watt Record Holder: 152.6db 2009 NSPL Car Hardcore Record Holder: 155.2db 2009 NSPL Car 3601-UP, Car Hardcore, and Car Points World Champion Posts: 1981 | From: The Triad | Registered: Jan 2008
| IP: Logged |
posted
Do you think the rubber stoppers could have unscrewed so instantly that they caused the overnight drop in spl? You may realize a slight gain(or loss) by tightening the hatch. Sometimes leakage is worth a gain especially if you've already tested and tuned the car with that existing leak. I would bet it's more an issue the subs and/or box. Then there's the matter of a new battery...is it conditioned and charged properly? Are your batteries matched brands/sizes, or a pot luck of this and that? Test, test, test!
Posts: 570 | From: streetsboro,oh | Registered: Jun 2005
| IP: Logged |
posted
Well, Eric my spl dropped over a 3 month period of time. My score dropped from a 149.7 to a 149.3 from a two week lapse in testing. Next event that I went to the score was down to a 149. I tested the following week and the score was at a 148.8 I didn't end up back on the mic until almost a month and a half later and the score was at the low of a 148.1 So this wasn't a sudden drop off, it happend over a 3 month period. It didn't just drop by 1.6 db's over night. The battery actually has helped my score in the car right now by .3 db's, so it is a definate good upgrade to the vehicle. I'm going to get back on the mic within the week and I should have my results. I'm pretty sure that this is the culpret of my loss. It also makes sense since my score was dropping off at each time of testing instead of just all at once.
The fact that all I did was retighten these little rubber pieces and all of the sudden I could hear a HUGE difference inside the vehicle leads me to believe that is where my spl was going. I've also done tests with the doors open and windows down and a door open actually hurts my score. The windows down does nothing to it, and the sunroof open actually adds .2 dbs. All this testing was done before the score started to drop off.
I recently had the batteries tested and they hold an excellent charge. After only having them on the charger for 5 minutes the voltage jumped up over 15 volts.
I also had them unhooked for several days and there was only a .05 volt loss overall on them being unhooked. A 1.6 db gain or loss is very noticable by ear, and I'm thinking that by sealing down the hatch again I've gained something even if it's not the entire 1.6 again.
Also to add the amps were pulled out and tested on the bench and make the same power on the bench with a power supply as they do in the vehicle which is a rms of 1800 watts.
I really just wanted to know if anyone thought that this may have been the loss of my spl, not what you think may have happened. I've checked everything over and over again and everything is in perfect working order except for these little rubber feet being out of place. The car has been stripped of all it's interior pannels and all seams and welds have been inspected thoroughly. The only thing left it to pull the spare tire out and check that particular area.
-------------------- TEAM SUNDOWN AUDIO 2009 NSPL Car 1801-3600 Watt Record Holder: 151.2db 2009 NSPL Car 3601-Up Watt Record Holder: 152.6db 2009 NSPL Car Hardcore Record Holder: 155.2db 2009 NSPL Car 3601-UP, Car Hardcore, and Car Points World Champion Posts: 1981 | From: The Triad | Registered: Jan 2008
| IP: Logged |
posted
Ive also seen this sort of loss when the suspension wears out on the subs. Being that you gained that 1.6 back with fresh 15's, I believed this may be the case. Of course 15's should be louder but that will all depend on if the box is right and how much reactive load the 15's have over the 12's. I also remember you posting about this same problem earlier where you said you lost 1.6dbz over the course of a week. That may have been posted under your AllNightLong user name rather than this one. Forgive me for trying to offer you some help but if it were just a matter of some out of adjustment hatch bumpers, everything else had been so thoroughly gone through, and it was clearly louder to the ear, why ask in a post if the problem is already solved....Zack.
Posts: 570 | From: streetsboro,oh | Registered: Jun 2005
| IP: Logged |
posted
Well, it's because I haven't metered the car yet is why I'm asking. I was only asking if it was possible to lose 1.6 db by not having a tight seal on the hatch.
The 12's used to do the 149.7 were freshly reconed subs. The 12's that also did the 148.1 were freshly reconed subs with the exact same parts as the 12's that did the 149.7
As for losing 1.6 over a week I don't ever recall posting that up cause I just recently did the lowest number ever with this equiptment in the car at the begining of Feburary. I lost .7 db's in a 3 week period of time. I've NEVER made a post about loosing 1.6 db's in my car EVER. I posted on 1-26-09 that I've lost 1.4 in my car which was 2 weeks before I metered and had the total loss of 1.6 db's and 2 months after I had the initial .7 db loss. Please refer to this topic. http://audioforum.termpro.com/topic/20/14320.html
Not once ever did I say this loss occured over a week period of time so next time please check your facts before trying to piece together your own version of the story.
If you recall my question in the first post it wasn't asking any questions refering to where my score went. It was asking if anyone thought it was possible that I could lose 1.6 db's by not having a tight seal on the hatch. Honestly that is the only question I am concerned with having answered and it's has been already. I'll gladly show you the much improved numbers when I meter the car later on this week. I am sure that this has made an improvement to my score enough to tell you so. The only other thing it could possibly be is something in the spare tire well since that's the only place I haven't checked. Everything else in the car has been checked and checked again and is absolutely fine. If this isn't the fix to the problem I'll consider my db's gone forever cause there is nothing else it could be.
-------------------- TEAM SUNDOWN AUDIO 2009 NSPL Car 1801-3600 Watt Record Holder: 151.2db 2009 NSPL Car 3601-Up Watt Record Holder: 152.6db 2009 NSPL Car Hardcore Record Holder: 155.2db 2009 NSPL Car 3601-UP, Car Hardcore, and Car Points World Champion Posts: 1981 | From: The Triad | Registered: Jan 2008
| IP: Logged |
posted
Well, good luck. Hopefully it was just your hatch. I can't ever recall losing Dbz with no viable reason. Then again, I'm not an installer like yourself and I've only been doing this since 05'. I have alot to learn.
Team Neo - Eric
Posts: 570 | From: streetsboro,oh | Registered: Jun 2005
| IP: Logged |
quote:Originally posted by tekk45: Well, good luck. Hopefully it was just your hatch. I can't ever recall losing Dbz with no viable reason. Then again, I'm not an installer like yourself and I've only been doing this since 05'. I have alot to learn.
Team Neo - Eric
Thanks anyway Eric. It's not that I don't appreciate the fact that you are trying to point out what you think it might be, I really just wanted the question that I asked answered. I'm aware of the possibilities that it may be in the car and is why I've been tearing it apart for the past couple of months trying to nail down anything that it could be. Everything you've suggested has been checked and is in order. I can tell you that I'm not the only person that has been in the car looking at what it could be either. There are other spl competitiors that have given me advice and also have helped to try and locate the problem. This is issue with the rubber stopers is the FIRST thing that has been out of line in the vehicle and is why I think that it might be the reason for the loss overall. We all know how the old it sounds louder by ear thing works and is why I was asking if this was theisably possible that I may lose 1.6 by the hatch not sealing correctly. Please don't take my comments out of context because the intent of them is not to contradict what you say. They are occurances of what actually happend in the car and the things that check out aren't worth rechecking at this point. If I continue my search and don't find a thing then I'll start to retrace my steps some
I hope that isn't necessary to do so and I have found the reason for the gradual decrease in score. I also find it rather hard to believe that you've never had an issue with your car where the score hasn't decreased at some point in time, unless that was part of your sarcasm as well. Each situation is different and if this is the case for me hopefully I can spread my knowledge onto someone else as you have tried with me. It is appreciated, but I don't feel that is where I need to look at this time.
I have a VERY good competition team behind me and we will get this solved before it's all said and done. I have confirmed with them that this is a possibility and wanted further confirmation from other sources to see if my theory is plausable.
-------------------- TEAM SUNDOWN AUDIO 2009 NSPL Car 1801-3600 Watt Record Holder: 151.2db 2009 NSPL Car 3601-Up Watt Record Holder: 152.6db 2009 NSPL Car Hardcore Record Holder: 155.2db 2009 NSPL Car 3601-UP, Car Hardcore, and Car Points World Champion Posts: 1981 | From: The Triad | Registered: Jan 2008
| IP: Logged |
posted
I did mention having this issue and why. I have lost score but have always been able to find the reason and ultimately move forward. Everything takes a beating in these cars. If it's not one thing it's another.
Posts: 570 | From: streetsboro,oh | Registered: Jun 2005
| IP: Logged |
posted
Here's the news. On the official NSPL mic I did a score of 149.4 and backed it up with a 149.3 to set the NSPL Car 1801-3600 World Record. I did however burp a 149.7 on a teamate's meter before I set the world record. I was able to get on the official NSPL mic again tonight so I'll go off those scores for a reference to my gain.
Overall I did a best score tonight of a 149.9, which was .5 db higher than my score last Sunday with only twisting in the little rubber knobs. There were two distinct things that didn't take place tonight that did on Sunday that helped my score out a bit. One was I didn't have anyone bracing the windshield which is good for .2-.3 db's and I wasn't on the battery charger before my burp which is also good for another .2-.3 db's. So if I had some more people to help me brace the windows and had been on the charger for an hour or so like I was on Sunday I could easily see another .4-.6 db's out of the car. Bringing the total gain in spl by tightening the hatch to a .9-1.1 db gain. Also if you add the .3 that the new battery helped you get a total of 1.2-1.4 missing db's accounted for. I'm pretty happy with the results. Even though this wasn't a spl build I think it has much more potential to get even louder with a more spl oriented box. The one I have now is tuned to 38hz and is not peaking anywhere near the car's resonant frequency. Not to mention that I have the subs in a larger enclosure then reccomended. I smell a new box in the works.
-------------------- TEAM SUNDOWN AUDIO 2009 NSPL Car 1801-3600 Watt Record Holder: 151.2db 2009 NSPL Car 3601-Up Watt Record Holder: 152.6db 2009 NSPL Car Hardcore Record Holder: 155.2db 2009 NSPL Car 3601-UP, Car Hardcore, and Car Points World Champion Posts: 1981 | From: The Triad | Registered: Jan 2008
| IP: Logged |
posted
Thanks Eric. I'm still going to check a few minor things that I haven't yet just to see if there's anything out of line there. If I find anything else I'll make sure to get on the meter again to see if there are any gains. The enclosure was built for music and does just that. It did measure consistant 149.5's at 40hz on music and in my opinion is a very loud daily driver. The subs can take the power that I'm giving them all day long so it's going to be hard to convince myself to build a more spl oriented box and possibly sacrafice some daily listening.
-------------------- TEAM SUNDOWN AUDIO 2009 NSPL Car 1801-3600 Watt Record Holder: 151.2db 2009 NSPL Car 3601-Up Watt Record Holder: 152.6db 2009 NSPL Car Hardcore Record Holder: 155.2db 2009 NSPL Car 3601-UP, Car Hardcore, and Car Points World Champion Posts: 1981 | From: The Triad | Registered: Jan 2008
| IP: Logged |
Printer-friendly view of this topic