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Do I use Amp crossover with components

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=61048
Printed Date: May 09, 2024 at 3:02 AM


Topic: Do I use Amp crossover with components

Posted By: Tegpilot
Subject: Do I use Amp crossover with components
Date Posted: August 10, 2005 at 1:16 AM

Hey guys, another newbie question that I know ya'll love to answer.  I have the new kappa 50.7cs and I tried to tune them in based on most instructions here.  They are rated at 85rms and 255 peak.  I using an MRV-F357 with below specs.  I turned the gain all the way down and started to turn up head unit (Panas CQC 5110U) volume with everything set to flat on the head unit!  When I heard distortion i backed up a notch and then proceded to turn up gain.  It didn't take very long to get distortion with the gain turned up, only about 1/3 of the way.  So with a Top volume level of 40 on the deck, I heard distortion @ 30 so backed it up to 20.  Oh yeah these speakers are 2ohm.  So with both the deck set and the amp set, I plugged in the old DMM and checked it.  With 1000hz and 800hz I only got around 7 volts max but with a music cd, hip hop, I got around 5 volts and 8 volts peak.  This works out to around 20-25 watts.  That just seems like it sucks.  Why the distortion at such low wattage??  Same thing on rear 6x9 kappa's. but they are 4 ohms so I got around 12volts constant with gain set fairly low.  I'm lost at this point.

Next question. I have a crossover for the components, one for the front channels and one for the rear channels Alpine amp and one on the Head unit.  Which crossover do i use, should I just rely on the Infinity crossover,  or the amp, or the deck???  Does the component cross just filter for the tweets and allow full range for the driver??? 

MRV-F357

Per channel into 4 ohms (CH-1 – CH-4) ..... 50W, 0.08% THD

Per channel into 2 ohms (CH-1 – CH-4) ...... 60W, 0.3% THD

Bridged into 4 ohms (CH-1 – CH-4) .......... 120W, 0.3% THD

4 ohms (CH-5) ......................................... 150W, 0.3% THD

MRV-F357

Per channel into 4 ohms (CH-1 – CH-4) ........................ 90W

Bridged into 4 ohms (CH-1 – CH-4) ............................ 240W

4 ohms (CH-5) ........................................................... 300W

Why can't I turn my gain up?  So many questions, thanks for all your help fellas!




Replies:

Posted By: DYohn
Date Posted: August 10, 2005 at 8:30 AM

You must use the crossovers supplied with the speakers to protect your tweeters.  I suggest you also should use the HP (high-pass) crossover on the amp and set it to the same as your subwoofer LP setting (if you have a sub) or to between 80-100Hz in any case to prevent your speakers from bottoming out.

As far as your voltage readings, did you take them with the speakers disconnected?  If they were connected the numbers you saw are meaningless.



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Posted By: Tegpilot
Date Posted: August 10, 2005 at 11:06 AM
Yes, the speakers were NOT connectecd.  And I am using the crossovers that came with the system, I was just wondering if they were enough!  Any idea on why my speakers are distorting with such little  power?  Could it possibly be that because my deck pre-outs are only 2.5volts instead of these higher ones like 4 and 5volts??  I mean, my speakers are peaking at half of their RMS power!  They sound great, but not very loud!  Well loud enough for my wife, but not for me you know what I mean. 




Posted By: DYohn
Date Posted: August 10, 2005 at 11:42 AM
I suggest you need to activate the high-pass on your amp and set it at 100Hz or higher for those 5-1/4" woofers.  Those are good speakers but they cannot produce bass at any kind of volume level.  You may be hearing them bottoming out.  And yes, your HU could be distorting.  RMS power is only for reference, by the way, and has not much to do with distortion.  If the speaker is distorting or if the HU or the amplifier is distorting or clipping has nothing to do with the amount of power, it has to do with the quality of the electronics and how it is set up and used.  Try the HP filter first.

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Posted By: Tegpilot
Date Posted: August 10, 2005 at 12:04 PM

thanks I'll try it and let you know what happens.

posted_image





Posted By: boulderguy
Date Posted: August 10, 2005 at 2:44 PM
I agree about the HP x-over, but if you're working w/o a sub & still want some semblance of bass, you could set the HP at say 60hz - you'd get more pure volume than full range but still a bit of bass.  Just remember those drivers were never intended to do bass, certainly nothing below 60hz.




Posted By: Tegpilot
Date Posted: August 10, 2005 at 3:25 PM

Yeah, I know they don't produce bass, but after I set my x-over at 100hz, I still recieve distortion at around 7-8 volts max which is fairly little power going to them>  Maybe I just am not understanding something.  Why can't I get more than 30 watts peak before these things distort, they're brand new.   Oh yeah, I do have a kappa 10dvq running in the trunk as well, so I don't need bass out of these 5 1/4 drivers, just good midrange :  drums, etc.  By the way, the tweets on these new 2005 model are so much more tuned down than last years kappa's.  They aren't too bright at all, and very smooth.





Posted By: DYohn
Date Posted: August 10, 2005 at 3:34 PM

Into a 2-ohm load your amplifier is rated at 60 watts, which corresponds to 10.95 volts AC.

Are you saying that with all speakers (and crossovers) disconnected and your meter set to AC volts connected to the speaker output, playing a 1000Hz test tone at 75% head unit volume you cannot achieve 10.6 volts output from your amplifier?  If this is what you are saying, then you are either doing something wrong or you have a defective piece of equipment (or a bad meter!)



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Posted By: Tegpilot
Date Posted: August 10, 2005 at 8:21 PM
No DYohn, I can acheive that voltage, with full gain, but with the speakers reconnected, I get  distortion even with the x-over set at 130hz.  So what I'm saying is that even at 60 watts, I should be severely underpowering these speakers, but instead I have to turn the gain down to 60% to not get distortion @ about even 60% head unit volume.  Meaning I can't turn anything up without distortion.  I can a good bit, but not achieving any amount of wattage.




Posted By: DYohn
Date Posted: August 10, 2005 at 8:31 PM

Then you have another problem (and you should not have to use "full gain" to get 10 volts from that amp!)  What is your HU?

-edit - Opps, I see, a Panasonic.  Well either it is producing a lot of distortion or your amp or speakers are defective.  If you set the gain properly, Kappa speakers will handle 60 watts and will not produce distortion on their own, usually.  They will however accurately reproduce whatever distorted signal is being fed to them.  Are you certain you have the speakers connected to the crossover correctly?  Maybe you are simply expecting too much.  Turn it down.



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Posted By: Tegpilot
Date Posted: August 10, 2005 at 8:54 PM
Well, I read my manual and it said to mount the x-over in the door, but because I wanted to showcase on my amp rack, I placed them in the trunk far away.  So i have a short wire running from my amp to x-over and then long wire's running to my tweets and drivers in the front door's.  Is this like a major no-no or something???  I do plan on putting them back on the door panel, but that is another thread in itself.   I want to make them look nice , but i think i'm gonna need some ideas first.   Thanks for your help by the way.




Posted By: DYohn
Date Posted: August 10, 2005 at 9:01 PM
Well, long wire runs from crossover to speakers is not the best idea, but it in itself is not necessarily the problem.  You can move them temporarily and use short wires and see if it makes any difference.  I was asking if maybe there is an out of phase speaker connection or maybe even a woofer connected to a tweeter output or something like that.  I don't know man, you may have to take it in and get someone to look at it to figure out what's going on.  It is sometimes hard over the Internet to get a clear picture... Best of luck!

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Posted By: Tegpilot
Date Posted: August 10, 2005 at 10:07 PM
Thanks, I think I'll mount the x-over in the door panels and see if maybe it helps somehow, eh, I might even find that I connected something wrong like you said.  thanks for all your help.  I going to post another thread on ideas for mounting and showcasing x-over casing in the door panel with pics of the door panel, maybe chime in and let me know what you think!  thanks





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