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Crossfire VS. RF


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thapimpfromchi 
Silver - Posts: 616
Silver spacespace
Joined: July 30, 2003
Location: United States
Posted: February 07, 2004 at 1:53 AM / IP Logged  
Hey guys, i was at my local car audio shop today, looking to buy amps. Here i am looking at a mammoth 4000 watt amp  (dont ask why, but i was), and the owner comes up, asks me what im lookin for, i say i need 1000 watts, minimum. He asks what i was powering. I tell him 3 MA Audio 100D6 subs. (350 rms x 3 = 1050) So yea, im lookin for a 1000 watt amp. Well, he said that using 1000 watts was absurd. That i didnt need that much power. (WTF!) Anyways, he goes over and points out a Crossfire amp. The VR600D amp. according to him, that amp puts out 800 watts at 4 ohms. His words were "this crossfire amp would walk all over your rockford." Right now, i am using a rockford fosgate 700s. (700watts @ 4 ohms). My computer has a virus on it, and wont let me bring up more than one browser, and doesnt like java scripts at all either. So, i couldnt really find info on that amp. However, i went to the only site that popped up, which was in japanese or something, and from what i could make out, that amp makes 150w @ 4 ohms, and 600w @ 1 ohm. if any of you has any info on that amp that you could share, that would be great. Also, assuming, i could find a similarly matched Crossfire amp (700 watts, for comparisons sake) which  amp would be better? the crossfire or the RF? Thanks alot.
1990 Honda Civic HB:
Clarion DXZ545MP H.U.
2- 6.5" Power Acoustik interiors
Diamond Audio 600.1 amp
Diamond Audio 15" M6MKII
Pyramid PB881X 4 CH. Amp
bfog99 
Copper - Posts: 212
Copper spacespace
Joined: June 04, 2003
Location: United States
Posted: February 07, 2004 at 2:42 AM / IP Logged  
these are the specs from the cross fire website:
Technical Specifications
High current Class "D" subwoofer amplifier, 150w x 1RMS into 4 ohms Continuously variable 12dB x-over between 50 and 250Hz, Continuously variable subsonic filter between 20 and 50Hz with on/off circuit, RCA preamp output, CFR-3 analog subwoofer level control, 600W x1 into 1 ohm

it did also say that it was 300 x 1 @ 2 ohms. as far as what would be better, i couldn't answer that. hope this helps.

customsuburb 
Gold - Posts: 1,813
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Joined: January 17, 2004
Location: United States
Posted: February 07, 2004 at 10:46 AM / IP Logged  
Your Rockford is fine. You dont need a crossfire it wouldnt be any better.
forbidden 
Platinum - Posts: 5,352
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Joined: November 01, 2003
Location: Alberta, Canada
Posted: February 07, 2004 at 1:59 PM / IP Logged  
Crossfire has been in the class D sub amp business much longer than Rockford and I as a dealer of both would sell a Crossfire over the Rockford any day. That Crossfire amp is way underrated as well, If memory is correct it has a 80 amp fuse recommended for it. What is the impedance of your subs? This will tell me what amp is best for you.
Top Secret, I can tell you but then my wife will kill me.
customsuburb 
Gold - Posts: 1,813
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Joined: January 17, 2004
Location: United States
Posted: February 07, 2004 at 2:20 PM / IP Logged  

forbidden

Why are you always comparing amps with their fuse sizes? It is like the roughest possible way to compare amps. Just read their specs.

forbidden 
Platinum - Posts: 5,352
Platinum spaceThis member has made a donation to the12volt.com. Click here for more info.spaceThis member has been recognized as an authority in Mobile Audio and Video. Click here for more info.spacespace
Joined: November 01, 2003
Location: Alberta, Canada
Posted: February 07, 2004 at 4:39 PM / IP Logged  

Amplifiers are called amps for a reason, they are not called wattlifiers for the same reason. The size of a fuse in an amp is a very good indication of what kind of output the amp is really capable of. Another thing to consider is the efficiency of the amp, a Class D Crossfire is on the average of 80% efficient vs. maybe 55% efficient in a Class AB Rockford. What happens to a lot of people that read specs is that they read what they want to see instead of what they need to see. For most people they do not compare things on a level playing field. An indication in this case of why I asked for the fuse size is fairly simple.

12 volts x 80 amps = 960 watts (at 100% efficientcy). This amp was only rated at 150 watts @ 40hm and 600 watts @ 1 ohm, this amp in particular has always exceeded it's recommended power, as do alot of others in the industry. It also has a subsonic filter built in to eliminate alot of wasted power, this in turn delivers much more of the amplifiers power into usable power in the amplified frequency range.Be it a good amp or not, it still has to be matched to the sub(s) properly, which is why I asked what the impedance is and now am asking for the number of voice coils, single or dual.

Top Secret, I can tell you but then my wife will kill me.
thapimpfromchi 
Silver - Posts: 616
Silver spacespace
Joined: July 30, 2003
Location: United States
Posted: February 07, 2004 at 5:02 PM / IP Logged  
this is for forbidden. I am looking to power 3-10" MA Audio 100D6, subs. They are dual 6 ohms subs. 350 watts rms, 700 peak. I currently have them wired down to 4 ohms, if neccessary i can go down to one ohm, but i prefer the cleaner bass.
1990 Honda Civic HB:
Clarion DXZ545MP H.U.
2- 6.5" Power Acoustik interiors
Diamond Audio 600.1 amp
Diamond Audio 15" M6MKII
Pyramid PB881X 4 CH. Amp
forbidden 
Platinum - Posts: 5,352
Platinum spaceThis member has made a donation to the12volt.com. Click here for more info.spaceThis member has been recognized as an authority in Mobile Audio and Video. Click here for more info.spacespace
Joined: November 01, 2003
Location: Alberta, Canada
Posted: February 07, 2004 at 6:04 PM / IP Logged  

Cleaner bass will have more to do with the box than the impedance that the amp is seeing. Your subs can either series / parallel wire to 4 ohm mono or all parallel wire to 1 ohm mono. In either case you need an amp that has a big bejesus output of 1200w rms at either 4 ohm mono or 1 ohm mono. This leads you to either a monster 2 channel amp that is on a real good day 70% efficient, or a class D which on a real bad day is 70% efficient. I would head in the direction of the class D mono sub amp, as some have a subsonic filter built into them. This filter will no doubt make a more efficient use of power and protect the subs from damaging bottom end. Either amp is going to have a good size current draw.

Now just because the subs say they can take 350w rms does not mean that you need to power them that way. Any sub can and will play with a lower power rating and do a great job at it, provided you do not throw a clipped signal into them. This is the danger of a amp that is too small and in some cases a cd player with a low preout ot clipped preout signal. If you are one that wants to annoy the neighbourhood with big bad bottom end that you want to play all the time, then you are the person who needs a big amp, more power than recommended is fine. Make sure that the gains are set right and do not clip the input signal from the cd player, as even the best amp that is too big can cause damaga to a sub if it is given a clipped signal from a cd player.

Top Secret, I can tell you but then my wife will kill me.
customsuburb 
Gold - Posts: 1,813
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Joined: January 17, 2004
Location: United States
Posted: February 07, 2004 at 7:17 PM / IP Logged  
An amp's damping factor (the amount of control the amp has on a speaker's movement) does goes down as the impedance drops. If you have a 1 ohm impedance your amp definitely wont have as much control over a sub as it would at a higher impedance. If you have some cash to spend JL's 1000/1 outputs 1000 watts RMS so it would it would be a good match for your subs because if you take 12volts times 100 amps (Which is the fuse rating reccomended for the JL amp) you get 1200 watts. And it has a subsonic filter which isnt that neccessary unless you have a ported box or bandpass box.
forbidden 
Platinum - Posts: 5,352
Platinum spaceThis member has made a donation to the12volt.com. Click here for more info.spaceThis member has been recognized as an authority in Mobile Audio and Video. Click here for more info.spacespace
Joined: November 01, 2003
Location: Alberta, Canada
Posted: February 07, 2004 at 7:23 PM / IP Logged  
Good point on the damping factor, I usually don't mention it. I bet the JL would be a great amp for those subs!
Top Secret, I can tell you but then my wife will kill me.
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