Bali Posted May 1, 2009 Report Share Posted May 1, 2009 is there any GOOD video tutorials that show how to set the amp with a multimeter? I don't have access to an o-scope so don't mention it lol. I saw the basics of doing it, but it was just for the gain/level and i need that plus sub sonic, bass boost, and lpf. ALSO, is a dual 2 ohm Fi BL 2 or 4 ohms? Or how many ohms is the frickin sub lol? Thanks. Link to comment Share on other sites More sharing options...
Sondre92 Posted May 1, 2009 Report Share Posted May 1, 2009 if you wire it in parallel it is 1ohm and in series its 4ohm 2003 BMW E46 320i TouringHU: Alpine CDE-177BT Speakers:Sub Amp :Subs: Box: Link to comment Share on other sites More sharing options...
Bali Posted May 1, 2009 Author Report Share Posted May 1, 2009 if you wire it in parallel it is 1ohm and in series its 4ohm i thought that was just the ohm load on the amp? Link to comment Share on other sites More sharing options...
dwz Posted May 2, 2009 Report Share Posted May 2, 2009 http://mobile.jlaudio.com/support_pages.php?page_id=143 Link to comment Share on other sites More sharing options...
MunkeyQ Posted May 2, 2009 Report Share Posted May 2, 2009 http://mobile.jlaudio.com/support_pages.php?page_id=143 Good guide there. Remember that you cannot measure impedance with a multimeter - ohms are the unit used for both resistance and impedance, which are two different things and people tend to get that confused. Resistance is simply that, whereas impedance is a function of resistance, capacitance and inductance. The speaker's voice coil is effectively a variable iron cored inductor. Therefore, impedance can only be measured at a given frequency and averaged, hence the term nominal impedance. Impedance changes over the frequency range of a sub greatly, and it is greatly affected by the tuning frequency of the port. A good example of this is if you build a ported box tuned for 60hz, put a suitably tough driver in it and plug it into the mains. Impedance rises sufficiently high - to around 30-50 ohms for an 8 ohm driver - to prevent current from being so great as to cause voice coil heating. Nasty subs to drive - like some of the Infinity line - are rated at 4 ohms nominal but will drop to 1 ohm when driven below Fs. Those are very hard on your amp. Link to comment Share on other sites More sharing options...
Torres Posted May 6, 2009 Report Share Posted May 6, 2009 i thought that was just the ohm load on the amp? exactly. a dual 2 ohm sub is just that. dual 2 ohms. different ohm ratings on subs allow for various wiring configurations for the amp. if you want a 1 ohm load, you get a dual 2 ohm sub and wire in parallel. get 2 dual 4 ohm subs and wire them both in parallel for a 1 ohm load on the amp. if you wanted a 2 ohm load on the amp, get a dual 1 ohm sub and wire in series, or a dual 4 ohm sub in parallel. Link to comment Share on other sites More sharing options...
bkolfo4 Posted May 6, 2009 Report Share Posted May 6, 2009 Nasty subs to drive - like some of the Infinity line - are rated at 4 ohms nominal but will drop to 1 ohm when driven below Fs. Those are very hard on your amp. I don't think you will see a sub's impedance fall below the DC resistance. The DCR of a 4 ohm sub should be around 3.2 ohms Brian 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. Link to comment Share on other sites More sharing options...
dwz Posted May 8, 2009 Report Share Posted May 8, 2009 I measure "resistance" with my multimeter. Just measure the resistance of each coil (as directed in the instruction manuals that came with it) while the power is off (obviously), if anything is funky then that's bad. Wire it up, and the wires should measure the proper resistance Link to comment Share on other sites More sharing options...
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