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Old     (ncsupra)      Join Date: Apr 2010       08-28-2013, 1:48 PM Reply   
I have two questions for the stereo guys:

1. Will I damage a 4 channel amp that is bridged but seeing 4 ohms on one side and 8 ohms on the other? The amp is an MB Quart Discuss 4125 Class AB amp with 2 channels bridged driving 4 ohms and 2 channels bridged driving 8 ohms.

2 .I also have a Kenwood KAC-8104D amp for a subwoofer. I would like to know what type of battery configuration I need to power both amps. We usually surf for a couple hours, then hang out on the lake swimming and listening to music for a couple more hours. How much battery power will I need to listen to the system for 4 to 6 hours? I have seen some posts for Optima, KenetiK and XS Power batteries but I donít know how many I need for my situation. For instance, will one Kinetik HC1800 be enough to power the system for 6 hrs?

Thanks for your help.
Old     (chpthril)      Join Date: Oct 2007       08-28-2013, 2:10 PM Reply   
1) nope, not at all

2) There are a lot of variables that come into play, such as system tuning, volume level, battery condition, amp efficiency, etc. Even then, coming up with an average current draw is a guess. The HC1800 is 81 Ah. A pair of these would be 162 total Ah and should get you well within your 4-6 hour range without having to deplete the house bank too deep. Another option worth looking into would be a pair of group-29 wet cells, About 200Ah for close to the cost of a single AGM.
Old     (Midnightv10)      Join Date: Feb 2012       08-28-2013, 2:15 PM Reply   

1. The minimum load you should put on a bridged amp is 4 ohms, so you should be fine with a 4 and 8 ohm load although I am curious as to what you are trying to do.. what are you planning on hooking up to that amp?

2. Depends on how you are playing the stereo (full on blasting or just regular listening) and also how you are maintaining the charge (alternator only or shore charger after each day)
Old     (ncsupra)      Join Date: Apr 2010       08-29-2013, 5:50 AM Reply   
Hi and thanks for the replies.

TigeMike Ė The term ďgroup 29 wet cellĒ is new to me. Does this mean regular deep cycle marine batteries that I can get off the shelf at auto stores, wally-world or Samís club? Will the guy behind the counter be familiar with it?

Russ, the short answer to your first question is an HCLD made by Selenium (DH200E). The long answer: After lurking on WW forums for a couple of years, I was intrigued by the DIY speaker enclosures some people were making. I designed a system with (4) Eminence BETA-8A speakers and (2) of the Selenium drivers mentioned above. I connected (2) Eminence speakers in parallel to each side of the bridged MB Quart amp. I then connected the Selenium drivers in parallel to a Cadence amp. Then, I had the sub-woofer connected to the Kenwood amp mentioned in my original post. The system SCREAMED, but I couldnít keep enough power to the amps, thus my question about battery power. I used this set up on a Supra 21V which I sold a few years ago. I just purchased an older Mastercraft Prostar 205. I donít think the tower can handle the weight of my original set up (approx. 65 lbs) so I thought Iíd use two Eminence speakers and one Selenium HCLD connected to the MB Quart amp. This way I can lighten the load on the tower and eliminate the Cadence amp.

To answer your second question: we would be listening to it fairly loud for a couple of hours and regular listening for a couple of hours. I plan to get a battery maintainer and plug it after each use. I will isolate my stereo power source from my starting/house power source.

Thanks for your time. I really appreciate your help,
Old     (chpthril)      Join Date: Oct 2007       08-29-2013, 6:52 AM Reply   

Batteries are typically labeled with a group number, which represents their size. Their physical size also plays into their CCA rating if its a cranking battery or its Amp/hour rating if its a deep-cycle. A group-29 is a common size for a marine deep-cycle. Same with a "AA", "AAA", "C" or "D" batteries for our flashlights and kids toys. Its common nomenclature.

"Wet-Cell" means its a traditional flooded wet-cell acid battery, as compared to a sealed AGM (Absorbed Glass Mat) Kinetik 1800 you are looking into.

Since battery reserve seems to be an issue, I would invest in a full-range Class-D 4 chnl and discard the old Class-A/B.


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