Wow, MA Audio amps are OVERrated

[RemlapaN 10+ year member]

I just installed a pair of MA Audio HK-598's

( http://www.maaudio.com/productcatalog.cfm?class=47472 )

rated for 4 x 200wRMS @ 4ohms...

And with a scope hooked up, I was getting clipping at 80w RMS running off the batteries (80w assuming there was a 4-ohm load).

I bridged one channel, and into a 2ohm load i could barely get 300wRMS out of it...

I know that my 1.5V head unit is part of the problem, but still, i think thats WEAK!

EDIT: wasnt in my car, was in a boat... I have 4 pairs of MBQuart NKD-116 6.5" components, and a pair of MBQuart NWD-254 10" subs... Sounds pretty **** good!

Click to read more...

 

[JimJ 5,000+ posts]

What was your supply voltage?

MA Audio HK series amps, if i'm not mistaken, are rated at 17VDC.

 

[InhumanAcura 5,000+ posts]

I just installed a pair of MA Audio HK-598's
( http://www.maaudio.com/productcatalog.cfm?class=47472 )

rated for 4 x 200wRMS @ 4ohms...

And with a scope hooked up, I was getting clipping at 80w RMS running off the batteries (80w assuming there was a 4-ohm load).

I bridged one channel, and into a 2ohm load i could barely get 300wRMS out of it...

I know that my 1.5V head unit is part of the problem, but still, i think thats WEAK!

EDIT: wasnt in my car, was in a boat... I have 4 pairs of MBQuart NKD-116 6.5" components, and a pair of MBQuart NWD-254 10" subs... Sounds pretty **** good!

sounds like you need to get a few things straight before you go off and say something is over rated..

What was your supply voltage?
MA Audio HK series amps, if i'm not mistaken, are rated at 17VDC.

not all of them...besides who and why the **** would you run 17v to a 4-ch amp...i mean seriously

 

[RemlapaN 10+ year member]

i was running off dual cranking batteries at the moment, so my supply voltage was probably 12.8, even if they rated at the typical 14.4V, thats only an 11% voltage drop. Even assuming it was rated at 17VDC, 12VDC is a 30% voltage drop, so wouldnt that mean I lose 30% of rated power, which should still put me at 140wRMS?

I fully plan on re-checking gains and outputs with the motor running, but obviously since it is in a boat, I cannot do that on land.

I did not expect 200wRMS from these amps off a battery, I am not that ignorant. 100wRMS would have been acceptable, since thats all the speakers are rated for anyways. The biggest complaint, is i lost all my headroom, since i need the HU running at 31/33 volume to get enough input voltage to the amps to produce at least 50wRMS output voltage.

I know that the cheap 1.5V line-outs are partially to blame here. If some company would make a high quality marine grade (READ: water-resistant) source unit, I would be installing that instead of the Clarion CMD4 i am using now.

InhumanAcura - what other things do i need to get straight before i call it overrated? I am not trying to be a smartass about your comment, just trying to educate myself.

 

[Beat_Dominator 5,000+ posts]

I can't vouch for that amp but my HK800D must have been **** close to it's rated power.

 

[audiolife 5,000+ posts]

not a big diff between 80 watts and 100 watts at all

 

[Randy Savage 5,000+ posts]

How did you calculate power numbers without calculating impedance?

 

[azbass 5,000+ posts]

buy my hk602sx //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[RemlapaN 10+ year member]

How did you calculate power numbers without calculating impedance?

Ohm'ed out the speakers, they are 4ohms at rest. Watched the wave on the scope, recorded the voltage just before clipping, then used W = V^2 / R. I know, I know... this isnt accurate since impedance changes based on cone position. But it should get me in the ballpark correct?

Dont get me wrong, on *NORMAL* modern music, the system has plenty of volume. The problem comes when i inserted a Bose demonstration CD, which is recorded very low, I assume to get a large dynamic range. At max volume, you could still carry on a conversation easily.

I will have to recheck gains and voltage with the motor running, see if the extra 2VDC makes a night and day difference.

I should have known they wouldnt produce 200wRMS x 4 when i saw the price... I got them for $180 each, shipped from an MA Audio distributor.

 

[RemlapaN 10+ year member]

buy my hk602sx //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

I would need 3 of them to do anything useful... I have 4 pairs of 6.5" components, and a pair of 10" subs. Right now, i have 2 pairs of the comp's wired in parallel for a 2-ohm load, and the subs are in parallel bridged across the amp. So im actually using 7 channels right now...

 

[audiolife 5,000+ posts]

bose? omfg why? you like elivater music?

 

[RemlapaN 10+ year member]

bose? omfg why? you like elivater music?

I dont like the music, it just does a good job for testing SQ of a system since it has a lot of instrumental, bass, vocals, etc.

 

[azbass 5,000+ posts]

I would need 3 of them to do anything useful... I have 4 pairs of 6.5" components, and a pair of 10" subs. Right now, i have 2 pairs of the comp's wired in parallel for a 2-ohm load, and the subs are in parallel bridged across the amp. So im actually using 7 channels right now...

//content.invisioncic.com/y282845/emoticons/rolleyes.gif.c1fef805e9d1464d377451cd5bc18bfb.gif

 

[klassic 10+ year member]

I know that the cheap 1.5V line-outs are partially to blame here. If some company would make a high quality marine grade (READ: water-resistant) source unit, I would be installing that instead of the Clarion CMD4 i am using now.

Explain to me how this is part of the problem? MA amps gains have sensitivity adjustments from 0.2-8V. There is no reason why 1.5V outputs wont allow full rated power. High voltage outputs only decrease the noise floor by allowing the amp to reach full power at lower gain settings they dont limit the amount of power an amp makes unless its putting out something below the amps adjustment range (like