Captain Stupid Posted September 30, 2012 Report Posted September 30, 2012 So, I determined today that a single DVC 4 18" sub in my box rises from 2 ohms to 3.5 ohms. That's a 75% increase! Just wondering, if I put a DVC 2 or DVC 1 18" sub in the exact same box, same vehicle, same amp, will the box rise be constant at the same percentage increase of 75%? Or will it incease at the same rate of 1.5 ohms? Or is the increase an unpredictable variable even when using the same box in the same space with the same amp due to the different power output and efficiency of the amp? 2006 Cadillac Escalade 2/3 drop on 28" wheels Two RE SX 18" subs RF T2500-1bdCP amp, 3531watts on birthsheet Custom carbon fiber sub box EVERYTHING else is stock, for now 149.4 @ 37hz, Termlab, dash, open window on two AQ3 18s all stock electrical, wired to .25 ohm on a RF T2500 148.8 @ 36hz, Termlab, dash, open window on one AQ3 18 all stock electrical, wired to .5 ohm on a RF T2500 147.8 @ 38hz, Termlab, legal, sealed on two RE SX 18s 146.4 @ 36hz, Termlab, legal, sealed on one RE SX 18 Link to my hack-built, stupid, carbon fiber wasting project.... http://www.stevemeadedesigns.com/board/topic/149946-carbon-fiber-box-update-1494db-37hz-on-tl/ http://gifsoup.com/NDM3MTc1MQ
bkolfo4 Posted September 30, 2012 Report Posted September 30, 2012 Did you check the impedance at every frequency? I bet it is higher than what you measured at some frequencies, maybe lower at others. It is not going to be 3.5 ohms at every frequency. If you want to measure it at every frequency you are playing (SSF filter setting to low pass filter setting), you can then determine if your amp can handle all frequencies and look at your options. But the obvious question - does your sub even need more power? Even if you cut your impedance in half, you will be lucky to gain 2 dB. Current system: 1997 Blazer - (4) Customer Fi NEO subs with (8) American Bass Elite 2800.1s Previous systems: 2000 Suburban - (4) BTL 15's and (4) IA 40.1's = 157.7 dB at 37 Hz. 1992 Astro Van - (6) BTL 15's and (6) IA 40.1's = 159.7 dB at 43 Hz.
Captain Stupid Posted September 30, 2012 Author Report Posted September 30, 2012 I do need more power, and have the chance to borrow another sub (DVC 1) to try out for a burp (idbl), so hoping to use it just for one or two burps at my peak freq. In order to score a maximum SPL score at a 3x event next week. And yes, 2 decibels would put me over the top of the competition. Amp is a RF T2500 that is only pushing 1860 clamped watts at 3.5 ohms. wondering where the DVC 1 will be with box rise if wired to .5 ohm. Obviously the RF amp wants to be at 1 ohm for best efficiency. Curious if the .5 ohm may rise to somewhere near 1 ohm by the time all is said and done....at my peak frequency only. 2006 Cadillac Escalade 2/3 drop on 28" wheels Two RE SX 18" subs RF T2500-1bdCP amp, 3531watts on birthsheet Custom carbon fiber sub box EVERYTHING else is stock, for now 149.4 @ 37hz, Termlab, dash, open window on two AQ3 18s all stock electrical, wired to .25 ohm on a RF T2500 148.8 @ 36hz, Termlab, dash, open window on one AQ3 18 all stock electrical, wired to .5 ohm on a RF T2500 147.8 @ 38hz, Termlab, legal, sealed on two RE SX 18s 146.4 @ 36hz, Termlab, legal, sealed on one RE SX 18 Link to my hack-built, stupid, carbon fiber wasting project.... http://www.stevemeadedesigns.com/board/topic/149946-carbon-fiber-box-update-1494db-37hz-on-tl/ http://gifsoup.com/NDM3MTc1MQ
Nikitaaa Posted September 30, 2012 Report Posted September 30, 2012 I do need more power, and have the chance to borrow another sub (DVC 1) to try out for a burp (idbl), so hoping to use it just for one or two burps at my peak freq. In order to score a maximum SPL score at a 3x event next week. And yes, 2 decibels would put me over the top of the competition. Amp is a RF T2500 that is only pushing 1860 clamped watts at 3.5 ohms. wondering where the DVC 1 will be with box rise if wired to .5 ohm. Obviously the RF amp wants to be at 1 ohm for best efficiency. Curious if the .5 ohm may rise to somewhere near 1 ohm by the time all is said and done....at my peak frequency only. Like I mentioned today Greg, be very careful with the power series amps and wiring to .5ohm. They are very touchy and there is a very good chance you might see magic smoke.. Some get lucky, others don't. It was good meeting up with you guys today though, I had a blast. 2007 M/T Honda Civic Coupe EX (4) Sundown Audio X-8's (2) Ampere Audio 3800.1's (3) Stinger SPV-44 Batteries (1) Mechman 240 3:1 Ratio 4th order sealed from the trunkTEAM NWSPLBest termlab scores to date in Honda trunk:151.7db legal (official) IASCA trunk 3 classBest termlab scores to date in my walled Subie:152.9db legal (unofficial) IASCA advanced 2 class155db outlaw
SnowDrifter Posted September 30, 2012 Report Posted September 30, 2012 Honestly, I'd only suggest doing .5 in a burp scenario of you know what your rise is at X frequency. And if you are sure you aren't clipping at all. But that being said, I run .5 daily. So YMMV ~~~~~~~~SAY NO TO PHOTOBUCKET~~~~~~~~ Snow's DD-1 tracks here: https://www.stevemeadedesigns.com/board/topic/167433-snows-dd-1-tracks/ My take on OFC vs CCA: https://www.stevemeadedesigns.com/board/topic/110381-things-that-piss-you-off-in-the-car-audio-world/?do=findComment&comment=2461444
STEvil Posted September 30, 2012 Report Posted September 30, 2012 You can burp at .5 if you adjust your gain. If you leave it where it is you'll probably run into serious clipping. MickyMcD - "Capable of making some serious trouser flapping volumes at where's-my-testicles frequencies, the Servo-Drives used to be fairly jaw dropping..." Any time you have have a power wire next to your frame put some rubber hosing (or cut up an innertube) around it. The wire is bound to wiggle (due to driving or flex) and the casing will eventually wear through. Hammerdown... 1% no links to outside websites, business related FB/YT pages allowed.
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