To bridge or not to bridge ? Related Question:
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From: Denny Strauser on 10 Jul 2008 21:52 I have a question along the same vein, but not about bridging. The club system I work with has 4 JBL Custom Shop 2/18" subs, driven by a MacroTech 5002 amp (run in stereo). So I have a choice of running 4/18" drivers per side either in parallel at 2 ohms, or parallel-series at 8 ohms. At first, I tried running all drivers in parallel (2 ohms per side), but the loud bands were hitting the amp limiters on every kick drum sound. So I wired the speakers parallel-series (8 ohms per side). But the amp was not putting out nearly enough power; and the X-over limiters were kicking in on every kick drum sound. Now, I rewired the subs back to all parallel. My question is: What impedance does the amp like to see? I'd prefer to have 2/5002 amps run at 4 ohms per side, but that's not likely to happen in the near future. Another consideration is that I have a dedicated 20 Amp AC circuit for that amp. Is a 20 Amp AC circuit adequate to run the amp full power at 2 ohms per side? Thanks, -Denny
From: Phil Allison on 10 Jul 2008 22:13 "Denny Strauser" > > The club system I work with has 4 JBL Custom Shop 2/18" subs, driven by a > MacroTech 5002 amp (run in stereo). > > So I have a choice of running 4/18" drivers per side either in parallel at > 2 ohms, or parallel-series at 8 ohms. ** Series connection of sub cabs is a *bad idea* !! Too much relies on the cabs being and more importantly * remaining * electrically identical for their whole lives. > At first, I tried running all drivers in parallel (2 ohms per side), but > the loud bands were hitting the amp limiters on every kick drum sound. So > I wired the speakers parallel-series (8 ohms per side). But the amp was > not putting out nearly enough power; and the X-over limiters were kicking > in on every kick drum sound. Now, I rewired the subs back to all parallel. ** Good. > My question is: What impedance does the amp like to see? ** The specs for the MA5002VZ say it can deliver a cool 35 amp rms into 2 ohms = 2500 watts. The 4 ohm load power involves only 22 amp rms - so the amp is 2 ohms capable. In any case, your JBL subs are only *nominal* 4 ohms loads - the actual impedance will be much higher at most operating frequencies PLUS as the 18 inch driver's voice coils heat at high power inputs, the DC resistance can rises to nearly double the room temp value. > Another consideration is that I have a dedicated 20 Amp AC circuit for > that amp. Is a 20 Amp AC circuit adequate to run the amp full power at 2 > ohms per side? ** Like I said, 2 x JBL 4 ohm subs is not really a 2 ohm load, but more likely around 4 ohms when running hard. So a 20 amp *nominal* AC supply ( well capable of 40 amp bursts) should be OK. ....... Phil
From: Denny Strauser on 10 Jul 2008 22:35 Phil Allison wrote: > ** The specs for the MA5002VZ say it can deliver a cool 35 amp rms into 2 > ohms = 2500 watts. > > The 4 ohm load power involves only 22 amp rms - so the amp is 2 ohms > capable. > > In any case, your JBL subs are only *nominal* 4 ohms loads - the actual > impedance will be much higher at most operating frequencies PLUS as the 18 > inch driver's voice coils heat at high power inputs, the DC resistance can > rises to nearly double the room temp value. > > So a 20 amp *nominal* AC supply ( well capable of 40 amp bursts) should be > OK. Thanks, -Denny
From: Phil Allison on 10 Jul 2008 22:44 "Denny Strauser" Phil Allison wrote: > >> ** The specs for the MA5002VZ say it can deliver a cool 35 amp rms into >> 2 ohms = 2500 watts. >> >> The 4 ohm load power involves only 22 amp rms - so the amp is 2 ohms >> capable. >> >> In any case, your JBL subs are only *nominal* 4 ohms loads - the >> actual impedance will be much higher at most operating frequencies PLUS >> as the 18 inch driver's voice coils heat at high power inputs, the DC >> resistance can rises to nearly double the room temp value. >> >> So a 20 amp *nominal* AC supply ( well capable of 40 amp bursts) should >> be OK. > > Thanks, ** That is a VERY rude way to reply - Denny. There was NO need to strip all your questions out of my post, thereby removing the context and making it incomprehensible. Plus you terse, one word response is meaningless. You are one very annoying little prick. ...... Phil
From: Phil Allison on 10 Jul 2008 22:59 "Denny Strauser" Phil Allison wrote: >> ** The specs for the MA5002VZ say it can deliver a cool 35 amp rms into >> 2 ohms = 2500 watts. >> >> The 4 ohm load power involves only 22 amp rms - so the amp is 2 ohms >> capable. >> >> In any case, your JBL subs are only *nominal* 4 ohms loads - the >> actual impedance will be much higher at most operating frequencies PLUS >> as the 18 inch driver's voice coils heat at high power inputs, the DC >> resistance can rises to nearly double the room temp value. >> >> So a 20 amp *nominal* AC supply ( well capable of 40 amp bursts) should >> be OK. > > Thanks, ** That is a VERY rude way to reply - Denny. There was NO need to strip all your questions out of my post, thereby removing the context and making it incomprehensible. Plus you terse, one word response is meaningless. You are one very annoying, smug, ASD fucked prick. ...... Phil
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