posted
Good question. Everything will be a matter of trial and error. Our truck has a huge cabin volume and our box is also quite large, but we have obtained a tuning of 68 hz only! Use the 1/4 wave frequency formula to get you started. Also, make sure you have three times the length from the rear of your driver to the mic as the length from your driver to the mic. Delaying your rear wave to reinforce your front wave will yeild great results.
quote:Originally posted by team basket kase: Also, make sure you have three times the length from the rear of your driver to the mic as the length from your driver to the mic. Delaying your rear wave to reinforce your front wave will yeild great results.
How are yopu measuring the distance from the front and rear of the driver? Are you talking about from the rear of driver, then toward the back of the box , around the port and then to the mic? I'm a little confused of what your talking about.
-------------------- Terry Shores 8 Time MECA World Record Holder Loudest Street Reality in 06' Back at it in 07'
posted
My measurement from mic to sub is 37in . If I measured correctly lenght from rear of sub to mic is 67in . How I came up with measurement was measuring the lenght of port because it sits on top of the subs in the wall , and added to distance of wall to mic , is that the correct way , or do you have to measure the depth of box as well to figure distance from rear of sub to mic ? Car is peaking at 38hz. on the mic and tuning is 34hz. for the box . 1/4 wave theory gives a resonant frequency of 54hz. ? Just trying to get some advice before I cut port to raise tuning ? I've gotten confused listening to alot of different people saying I needed to tune to resonance of cabin and then others said resonance changes as spl increases due to car flex and not being airtight as an extreme vehichle would be. Thanks for the response , keep em coming ? Posts: 281 | From: Indiana | Registered: May 2002
| IP: Logged |
posted
You need to measure from the center of you sub's magnet to the rear center of your box to the center of your port and then to the mic. That number should be three times the distance as it the number from the sub's dustcap to the mic. Your 1/4 wave note is 13560 divided by 4 divided by the distance (in inches) of your dustcap to the mic. Our subs are 48" with a tuning of 70 hz. The less the distance, the higher the tuning. Our system only plays one high note, it does not play music. This is where you must play with all the data of your system to aquire the results you want. A very large port with a shallow length will boost your frequency and then plugging in a "small port" adapter will get back your street bump sound. It's the only way to go when you want the best of both worlds! This article is in Car Audio and Electronics mag, March 2002 on page 76. PS- It works!, especially for spl only boxes.
posted
Ok what if u have a half wall like in a car say you take out the back seat and make the box below the windows?How would you tune it then?Or would it affect it at all??
-------------------- DiRtY SoUtH DEAF SqUaD Team Hazard Posts: 471 | From: jonesboro,ar,usa | Registered: Jul 2001
| IP: Logged |
posted
Hey DK! Haven't heard from you in a while! Email me and let me know how everything's going, umKay! This is an absolutely true statement. Especially in no wall setups. You should tune about ten hz lower than the frequency you want to play. This will allow your car's cabin gain to naturally boost your box frequency. 1/4 wave numbers often work but I have concentrated on ss 1-2 for 2 years and haven't played with other setups as much, so, my knowledge is pretty accurate when it comes down to walls , and with subs stacked on the passenger side. This is where 1/4 wave numbers seem to be at their best. It is always a matter of trial and error. It took us 16 rebuilds to get to where we are right now, and that is only for today - tomorrow - is another story!
posted
Ok I measured from rear of magnet to the rear box wall 39in , from that point to center of box to center of port 50in , from that point to mic position is 45 in . Center of dustcap to mic is 43 in. . According to this formula I need to be at 44.6 in . Then If I use the 1/4 wave formula my note is 78.8 . Well so far 2 different mics are reading 38hz. as my peak between 156 and 157db with 2 1500watt monoblocks and 2 18s voltage is a constant 13+ when testing . Net displacement of interior box is 19.5cbft port is 337sqin 18.5 in. deep for a tuning of around 36hz. according to winisd . Well what do you think I should do to increase ? Last thing this is in a 93 probe and I have 2 more 1500watt monos in reserve trying to figure bestway to wire one per voicecoil safely ?
Posts: 281 | From: Indiana | Registered: May 2002
| IP: Logged |
posted
It sounds like you got a good thing going! Your rear wave is 3 times the distance as your front wave which is excellent. Is it possible for you to increase your port area any? Also, your port length is pretty long. If you were to shorten that length, you would see a higher tuning frequency develop. If you are looking for the highest spl possible, you gotta get that tuning as close as possible to that 78 hz number in your formula. What kind of subs and amps are you running? What impedeance are your coils? And can you add those other amps in? You should be able to pull low to mid 60's easy! You're right on track otherwise.
posted
Well in the probe it's a tight squeeze the wheel wells are 38in apart and the height is limited to 30in for the box . In order to make port bigger the face would have to be cut off and rebuilt inside of car , for now I want to max out the current design if I can get into 160s with this vehichle I will invest more . The subs I'm using are 18in. Inhuman dual spiders with 2ohm dvcs . I each sub have wired parrallel to an mtx81000d a piece . At rest impedence measures 1.2ohms , while playing impedence bounces between .7ohms and 11ohms . I'm working on getting the amps in , I've got everything just trying to figure which way to wire subs for maximum output and safty , one per coil in parrallel or 2 amps linked with the sub wired series ?
Posts: 281 | From: Indiana | Registered: May 2002
| IP: Logged |
posted
What is your primary goal? Are you looking for a system to listen to and also be able to hit a 60 with, or do you want a one note spl system to pull in big numbers with? The amps you have now should run nicely on 2 ohm coils. If you dropped 8 of those amps on those subs - whoa jack!!- big spl! You already have nice spl at your current tuning and if it sounds good, bonus! But I don't see why you can't hit each coil with it's own amp as it is. Your spl will surely increase. These amps are really power hungry, as I just found out!!! A battery for each amp will help to stabilize your power needs. Feel free to email me at teambk@juno.com if you want and we can work on getting ya straight!!! Always glad to help when i can!
posted
I sent email about a week ago ? Anyway I've been busy working on it so far I added 3in. to front height 1in to depth and 3in to height of port giving me 21cbft and 434sqin of port , so far I've got it painted and permently attached to car . Also have amps and batteries diagramed and matched installing subs tomorrow . Still feeling the effects of the paint lol . Seen your truck on dbdrag leaderboard mean looking setup . Someday I'll get their lol .
Posts: 281 | From: Indiana | Registered: May 2002
| IP: Logged |
posted
Ok, I'm having trouble with this 1/4 wave stuff. What all do I need to measure? dust cap - mic = 47 inches back of magnet - center back of box = 38
What other measurements do I need to make? My enclosure is 14.5 cubes 300inches of port 4 inches long tunned to around 54htz, although I peak @ 50htz?? I tried tunning higher but lost dbs. I think my little prelude should peak higher. Any help would be appreciated.
-------------------- 2003 8th place World finals finish Loudest 1st Gen crx in the WORLD Loudest street A slotport Team DB Audio Loudest stock Car at usaci finals 159.8 Posts: 1405 | From: tulsa, ok | Registered: Jun 2001
| IP: Logged |
posted
I can't really help you , just wanted to say the setup in your prelude is very similiar to my probe , the difference is my subs are on bottom ports on top of wall , the similarities are cabinspace , distance of subs to mic , distance rear of box to center of port , distance from rear of magnet to back of box wall , my tuning when calculated for 1/4 wave came out to 78hz. DB Don says that 1/4 wave does'nt work as well in ss1-2 as it does in extreme 1-2 and that tuning for vehichles such as ours , is alot lower than 1/4 wave figure generally speaking . So far testing is showing peak is between 48-52hz. for my setup , will post results here of the tests should get it done next weekend . Lastly just wanted to add your car is cool and that the surround of wall has given me a few ideas on how to finish the surround of mine , thanks for posting pics .
Posts: 281 | From: Indiana | Registered: May 2002
| IP: Logged |
posted
I just think I should peak higher because of the smaller cabin space.
I was doing 57-58 in slap with 230in of port There is more port now, those pictures show 230 inches of port and I have 300 now. Also putting in 1 RE 18xxx and see how I do. I'm tall (6'2'') and this is my daily driver so I had to set the wall back a little and just glassed it in, was easy and I can scoot the seats all the way back
-------------------- 2003 8th place World finals finish Loudest 1st Gen crx in the WORLD Loudest street A slotport Team DB Audio Loudest stock Car at usaci finals 159.8 Posts: 1405 | From: tulsa, ok | Registered: Jun 2001
| IP: Logged |
posted
Looks like you got plenty of wall left to convert into port area!!! Your box numbers are quite small, and as you may know-or not-, our space is much larger. I can't speak from experience on small box DD numbers, but I would assume that your tuning would be quite high. DD's love big boxes, and big ports. Also, a butload of power!!. Power is our way of forcing the subs to produce numbers. We are barely getting 600 volts total to our subs, and peaking at 165 db, or so! Best of luck to you guys, and I'll be keeping an eye on y'all!!! Something's buggin' Team BK 2K3!!!
![[Big Grin]](biggrin.gif)
![[Smile]](smile.gif)
Printer-friendly view of this topic