ohm load on Ma Audio amp
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=67686
Printed Date: May 04, 2025 at 2:14 PM
Topic: ohm load on Ma Audio amp
Posted By: ddsubman
Subject: ohm load on Ma Audio amp
Date Posted: December 05, 2005 at 9:44 AM
Hi everyone! I'm new to this forum and was hoping someone out there could help me. I am running an ma audio hk4000d in my 96' yukon. It is powering a 9515 Digital Designs sub in a 8.5 cubic foot ported box. Here is my problem..When I purchased the sub it was a 2ohm dvc model, I smoked it after almost three years of daily driving and competing in NSPL and Dbdrag. When I got it back from DD after they rebuilt it, I noticed they sent it back as a dual 1 ohm model. I wired the sub in series (vc1+to amp/ vc2-to amp / tied vc1- and vc2+ together) I am assuming this would make a 1 ohm load. It seems a lot louder to me at 1 ohm, but Ma audio does not recommend running the 4000d at 1 ohm. Does anyone know what kind of power the amp may be making at 14.4v at 1 ohm, and will my amp hold up? Also would it be possible to parallel the vc's on my sub and pull a 1/2 ohm load? How much power would it make?
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Gettin' deafer by the day.......96' GMC yukon-Eclipse CD 5442HU
MA Audio HK4000D-Digital Designs 9515F
150+db with one woofer...DD rules!!!!
Replies:
Posted By: DYohn
Date Posted: December 05, 2005 at 11:17 AM
DVC 1-ohmvoice coils in series creates a 2-ohm load. Two of these in parallel creates net 1-ohm, in series net 4-ohms. MA amps are rated as stable to 2-ohms, so I recommend wiring for a net 4-ohm load. Unless, that is, you don't care about possibly frying the amp due to overload and/or the speakers due to clipping. ------------- Support the12volt.com
Posted By: haemphyst
Date Posted: December 05, 2005 at 11:25 AM
I know little to nothing about that amp, but here goes...
If the VCs are in series, and the amp is a mono amp, you are running the amp at 2 ohms ( a safe oeration condition). If it is a stero amp, and you have it bridged, you are runnning at 1 ohm (an unsafe operating condition). If MA Audio does not recommend running at one ohm, but if you are actually running in the first configuration, you are safe.
If you wire the coils in parallel, this would make a 1/2 ohm load wich would be FAR into unsafe territory ( 4 TIMES the already unsafe load recommended by the manufacturer), and this makes me believe you don't understand enough about impedances and Ohm's Law. Please read as much of this website as you can... ------------- It all reminds me of something that Moličre once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."
Posted By: ddsubman
Date Posted: December 05, 2005 at 2:11 PM
If you wire the coils in parallel, this would make a 1/2 ohm load wich would be FAR into unsafe territory (4 TIMES the already unsafe load recommended by the manufacturer), and this makes me believe you don't understand enough about impedances and Ohm's Law. Please read as much of this website as you can... I realized my error about what ohm load I am running. I still want to know what kind of power the amp will make at 1/2 ohm load....I was hoping someone with Ma audio amplifier experience could let me know what experience they have had with their amps...As many people know, not all amps are created equal. I have had many amps that were only rated at 4 ohms that performed flawlessly at 1 ohm or less. I was just wondering if anyone else had tried it before and what experience they had before I rewiRED / fried a $750 amp. I would only be running the amp under these conditions long enough to get a meter reading at the next NSPL competition. It would be reverted back to 2ohm operation for ride around purposes. Thanks. ------------- Gettin' deafer by the day.......96' GMC yukon-Eclipse CD 5442HU
MA Audio HK4000D-Digital Designs 9515F
150+db with one woofer...DD rules!!!!
Posted By: DYohn
Date Posted: December 05, 2005 at 2:26 PM
ddsubman wrote:
I still want to know what kind of power the amp will make at 1/2 ohm load.
Probably zero, as it will most likely shut down in protection or fry at that load. Mobile Authority amps are not very robust, in general. ------------- Support the12volt.com
Posted By: ddsubman
Date Posted: December 05, 2005 at 2:45 PM
DYohn] wrote:
P>[Probably zero, as it will most likely shut down in protection or fry at that load. Mobile Authority amps are not very robust, in general.
Thats' funny.. After almost 2 weeks I finally received a reply from MA's tech department. The tech guy assured me that with the protection removed the amp would easily run all day a .5 ohm. The question remains the same now as it did 5 hours ago..Just pretend my Mobile Authority amp is a "robust" high end unit capable of producing 3600watts at 2ohms and 14.4volts. Now approximately how much wattage will it produce at .5 ohm load. ------------- Gettin' deafer by the day.......96' GMC yukon-Eclipse CD 5442HU
MA Audio HK4000D-Digital Designs 9515F
150+db with one woofer...DD rules!!!!
Posted By: stevdart
Date Posted: December 05, 2005 at 2:56 PM
You will have to measure it, as the answer is not a math equation. Perhaps the MA tech can fill you in with that info too. I'll explain it like this for those who will read this thread: say, you have an amp that has been measured by the factory and rated at 2 ohms and at 4 ohms. You can figure the output in between those ratings, and you can figure the output at a higher load than 4 ohms. But to figure the output at a lower load is just guessing because you don't know what the limitations of the amp's rail voltage are. You can't assume that if the rating at 2 ohms is whatever, that the output at 1 ohm is double that. Or that the output at 1/2 ohm is double the 1 ohm rating. You could find....by measuring....that the output at 1 ohm is the same as it is at 2 ohm or maybe just a bit more. Limitations imposed by the amplifier build. And generally, putting a load on any amplifier that is lower than the lowest power rating given by the manufacturer is a bad idea. Cheater amps, that is, those that are well known, are the exceptions to the rule. But be sure. ------------- Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.
Posted By: youngone
Date Posted: December 05, 2005 at 3:09 PM
4200 to 5000w at .5ohms. it will be very risky to pump that amp that high. And that amp is a good quality amp gust not for sq. it is gust designed to push a lot of power. i don't know about that much though. .5ohms is real close to the point that you will have a big problem with the system as a hole. that is a huge amount of power to draw from your car, even if it is made for that the AMP is not made to allow that much power to go throw it. And i don't really know how it would do under that condition. it is VERY risky to do. i do not recommend doing it. and if you do i would recommend having a fire extinguisher handy.
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Want to know some good equipment- JL,Adire Audio,Mcintosh,Brax,Helix,Eclipse,JBL,RE,Dimoand Audio,Zapco, pritty much anything DYhon,Forbidden recommend
On the12volt you give some info and you get in
Posted By: ddsubman
Date Posted: December 05, 2005 at 3:17 PM
Thank you, that is as close as I have come all day to getting an answer to my question...Would you be willing to tell me how I could measure it? I really don't want to wait another 2 weeks to get a reply from MA. In their last reply all they did was tell me it would work and sent me a diagram showing what resistors to remove to kill the protection. I came to this site for help, not to be told how dumb I am when it comes to car audio and how bad my choice of amplifier was...... "To be, rather than to seem.." ------------- Gettin' deafer by the day.......96' GMC yukon-Eclipse CD 5442HU
MA Audio HK4000D-Digital Designs 9515F
150+db with one woofer...DD rules!!!!
Posted By: stevdart
Date Posted: December 05, 2005 at 3:30 PM
Relax, David. Your attitude is showing. Measure the output at the speaker terminals in AC volts. Use Ohm's Law to find power given the two knowns that you will now know: voltage and impedance load. P = E^2 / R It's accurate to do this with a bench test, but doing it in the car will get you close. And keep the sub unhooked while you do it. Use a 50 Hz test tone recorded at 0 db. But you should have first found the point of clipping with the tone and the sub hooked up. Unhooking the sub to measure voltage just takes the strain off the sub while you're doing the voltage test, because it's not necessary to hear the tone at this time. ------------- Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.
Posted By: youngone
Date Posted: December 05, 2005 at 4:16 PM
steve is right you can do that. and you did not make a bad decision on the amp you chose it was actually a very good choice in your application. you wanted a huge amount of power with no regards to sq. and there is nothing wrong with that it is all about the setup. especially in the competing world. and i have heard of people powering there subs with a ma audio amps. there is a guy on hear that has a 4400w ma amp don't now what the type it is though. he is powering a ma hard core 18'' with it and he is has the loudest car in his area. i think he has hit 160bd to 170bd don't remember the exact rating. and believe it or not he is running it at .5ohms ya it would be able to take it but it would take some rigging. it would only be able to do it for a short period of time.
-------------
Want to know some good equipment- JL,Adire Audio,Mcintosh,Brax,Helix,Eclipse,JBL,RE,Dimoand Audio,Zapco, pritty much anything DYhon,Forbidden recommend
On the12volt you give some info and you get in
Posted By: jeffchilcott
Date Posted: December 05, 2005 at 5:04 PM
I noticed you said Mobile Authority earlier, hoping this was just a mistake....MA is owned by the same company that makes Mobily authority, but they are far from the same product
Yes these amps will run at .5 with the protection removed, they will actually go down to .25 if you have 16+ volts on them
I am a USACi compititor and have watched these amps go to .25 ohm, with a constant 16-17volts.....you need alot of money for your charging system though, more or less batteries and about $800-$1000 worth of them.
I would not recomend running these amps below thies recomended load, unless you have numerous batteries and or alternators, they drain alot of curent, and the protection curcuit is not 100% fool proof, the first time you under volt them with out the protection curcuitry you will pop the amp, and more then likely it will be very costly to fix.
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2009 0-1000 Trunk WR 154.0DB 2009 1001+ Trunk WR
2007 USACI World Champion
2007 World Record
2006 USACI Finals 2nd Place
Posted By: ddsubman
Date Posted: December 05, 2005 at 6:02 PM
I only referenced Mobile Authority in my earlier post because I assumed that was what one of the members was comparing MA to when he said they were not "robust, in general". I really appreciate the feedback on MA amps from jeff and youngone. The info from steve will be very useful as well. I am currently competing in NSPL here in N.C., and am looking for a slight edge on my competition, that's why I came to this site. Right now I have the loudest beginner truck/suv 0-500 in my area with only one sub and one amp. It has been metered at 151.6 on the linear x meter and 147.7 on the new termpro meter currently being used by NSPL. I am running 4 SVR dry cell batteries with an eclipse HU. I appreciate all the help I've received today, hopefully I can yank out those pesky protection resistors tomorrow and do some testing with my voltmeter. Also, for those of you reading this thread, please don't confuse frustration with "smarter than thou" members for attitude. I thank all of you.
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Gettin' deafer by the day.......96' GMC yukon-Eclipse CD 5442HU
MA Audio HK4000D-Digital Designs 9515F
150+db with one woofer...DD rules!!!!
Posted By: jeffchilcott
Date Posted: December 05, 2005 at 7:07 PM
How large is your enclosure for your sub? I am not fimilar with NSPL rules, so I dont know if you can do blow thru's and such..
I know at Usaci I didnt see them in anything larger then a 1.5cuft box per sub...strictly SPL use.
Like I said I run in USACi but if you let me know some of the main rules you have to follow I will do my best to offer and suggestions I can.
Our best to date
153.5db Outlaw Term-Lab (Meghan Bailey)
301-900 Basic Stock
1 battery under the hood (kenitik hc2400)
(2) Crossfire 1000d's 500RMS@4ohm
(2) Kicker L7's 12"
All audio equipment subs/amps must be behind the strut towers in a hatchback vehicle...I.E our CRX
We used a 1st gen rex, not the easiest to get loud in. I am sure you see plenty of 2nd gens in your org too
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2009 0-1000 Trunk WR 154.0DB 2009 1001+ Trunk WR
2007 USACI World Champion
2007 World Record
2006 USACI Finals 2nd Place
Posted By: ddsubman
Date Posted: December 05, 2005 at 9:03 PM
In NSPL beginner truck suv class, the only rule for box size and design is that it must be lower than the top of the passenger seat. My box is 8.5 cubic feet, the port is tuned to 45hz. I run in the 0-500 class, which is very strict competition when you take into consideration all of the cheater amps out there...There are many seasoned veterans in the "beginner" class. Basically the only thing that would stop anyone from running in beginner truck/suv is if they have a wall or are sponsored by someone in the 12 volt industry. To date, I have never been beaten in my class by someone with 1 sub/amp. Usually it takes at least 2 and a lot more power!
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Gettin' deafer by the day.......96' GMC yukon-Eclipse CD 5442HU
MA Audio HK4000D-Digital Designs 9515F
150+db with one woofer...DD rules!!!!
Posted By: jeffchilcott
Date Posted: December 05, 2005 at 9:29 PM
I dont know if you have tried it yet....try something along the lines of a 1.5-2.0 cu ft box tuned to around 50-55hz with the sub and port up...or sub forward and port up.....from what I have found in trucks they do the best with subs and ports up....port as close to drives side as possible
with sub forward it is in the dead middle, and the port to the drivers side pointing up
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2009 0-1000 Trunk WR 154.0DB 2009 1001+ Trunk WR
2007 USACI World Champion
2007 World Record
2006 USACI Finals 2nd Place
Posted By: ddsubman
Date Posted: December 05, 2005 at 10:28 PM
Thanks for the info Jeff, I've got an old box in my garage that is about 2cu ft. I'll make a new face plate and port for it and try it out before the next show. I'll let you know what I found..
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Gettin' deafer by the day.......96' GMC yukon-Eclipse CD 5442HU
MA Audio HK4000D-Digital Designs 9515F
150+db with one woofer...DD rules!!!!
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