Stetsom 7kd 16v, 7kd 12v, New 7k2d 12v compared.

[dtbrown 10+ year member]

I'll make this clear now since most people won't read to far into post and only look at numbers. This is only a spl and power comparison test. The NSB90 battery used in test is a 4 year old NSB90 that is about .5db down from newer NSB90. The battery is good for burps but doesn't have the the amps it used to. CS9000 is almost new.

This test is to compare 7KD 16v, 7KD 12v and new 7K2D modified 12v version.

NOTE: Seven 2200mf capacitors added to 7K2D to make it a 12v version. Standard 7K2D is as strong as the older 7KD 12v and more efficient.

7KD 16V @.5ohms Only mod is copper bars instead of fuses.

NSB90: 3200-3300w, voltage drop 10.7v, 153.0db

CS9000: 4200-4300w, voltage drop 11.3v, 153.8db

Video

http://s171.photobucket.com/albums/u307/dtbrown1978/?action=view&current=SANY0399.flv

7KD 12V @ .5ohms

NSB90: 4000-4100W, voltage drop 10.4v, 153.5db

Video

http://s171.photobucket.com/albums/u307/dtbrown1978/?action=view&current=SANY0400.flv

CS9000: 5000-5200W, voltage drop 10.7v, 154.3db

Video

http://s171.photobucket.com/albums/u307/dtbrown1978/?action=view&current=SANY0404.flv

http://s171.photobucket.com/albums/u307/dtbrown1978/?action=view&current=SANY0404.flv

7K2D Modified 12V @.5ohms (Seven 2200mf capacitors added. Standard 7K2D is as strong as the older 7KD 12v and more efficient)

NSB90: 4200-4300w, voltage drop 10.3v, 154.0db

Video:

http://s171.photobucket.com/albums/u307/dtbrown1978/?action=view&current=SANY0410.flv

CS9000: 5500-5600w, voltage drop 10.7v, 154.7, 154.8db

Video: Explains why there is more spl gain but not much power gain vs the 7kd 12v.

http://s171.photobucket.com/albums/u307/dtbrown1978/?action=view&current=SANY0412.flv

http://s171.photobucket.com/albums/u307/dtbrown1978/?action=view&current=SANY0417.flv

Conclusion: You'll notice that the 7K2D only does a little more power than the 7kd 12v but does .5db louder. The power tests doesn't relate to the spl gain. Watch the videos because it'll show that even though the amperage is close to the same as 7kd 12v the spike voltage on the 7K2D is very high compared to the real time voltage. The amp wants to make more power but is unable to due to battery limit. And the 7k2d holds it's power vs the 7kd 12v falls off 4 volts after initial burp. That's some of the reasoning for that. I could have used the spike voltage for my power test but it was never consistent and would have given me power from 6500-7000w. So I decided to use the real time voltage because it was very consistent but I still recorded box spike and real time voltage if anyone wants to know what the spike voltage was. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

But that the new 7K2D 12v is more efficient than the older 7KD by a lot. The 7K2D has same voltage drop as older 7KD 12v and is .5db louder shows it's efficiency. This amp wants to produce even more power and I can see this amp easily producing it's rated power at 12.6v. Fantastic job Stetsom. You really needed a more efficient amp and you went above and beyond that. Can't wait to test it at 1ohms for music on two CS9000's vs 7KD at 1ohms for music.

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[hazardous0388 10+ year member]

good review jeff. glad to see you got tests on the amplifiers to put on the forum. i still cant believe how massive those ports were when i saw them when i took the trip up there...

 

[Zeuslicious 5,000+ posts]

Thanks for the Info and Just like Dustin said, Great review...

I Can't wait to see your test it at 1ohms for music. I might get one of this Amps BUT, it will be nice a review of the new 7K2D 16v version. Who knows if it's going to be more efficient for Daily...

Thanks

Chris

 

[dtbrown 10+ year member]

Thanks for the Info and Just like Dustin said, Great review...I Can't wait to see your test it at 1ohms for music. I might get one of this Amps BUT, it will be nice a review of the new 7K2D 16v version. Who knows if it's going to be more efficient for Daily...

Thanks

Chris

ok, not to confuse anyone but this amp only has 7 extra capacitors from stock which allows the amp to hold power for burps instead of falling off quickly like the 7kd does. Watch video's and you'll see what i'm talking about. This amp can still play music great but is better at burps for competition then stock one is. The standard version at 1 ohms is almost as much power as the one i tested. The standard 7k2d was designed to do great power from 10v up to 15.5v and anything higher will go into protect. So standard 7k2d is just normal no 12v or 16v. But stetsom will offer the 7k2d in a 16-18 v version. Hope that clears things up.

 

[dtbrown 10+ year member]

Originally posted by Tinted:[qb] 7k2d on nsb made only 200 more watts than 7kd but is a 0.5 db gain?

At the same time it made 500 more watts on the cactus batt than the 7kd but it also only produced a max of 0.5 db gain? interesting.

also interesting that 7kd made 800 more watts on the cactus batt than the 7k2d did on the nsb, yet is only a 0.3 db gain.

good test, thanks for the info. [/qb]

Got more of an answer about this. After some brain storming we forgot to factor in efficiency into the power numbers. Reason that power numbers are so close is because the difference in efficiency between the amps.
Now I don't have a DC clamp meter so was unable to figure exact efficiency. But to give you an idea take the power of the 7kd 12v of 5200w and times it by 70% (estimated efficiency) or .7 is 3640. Then take the power of the 7k2d of 5600 and multiply it by 80% or .8 you get 4480. Now guestimating the difference in efficiency was 10% you get a power difference of 840 instead of the initial 400 before efficiency was factored in.

So I'm going to have to assume that's the reason for large spl difference and little power difference.