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Old 21st February 2008, 03:27 PM   #1
Dan2 is offline Dan2  South Africa
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Join Date: Sep 2005
Default Mids question

Please help me understand this...

i have a single 12 sub in a sealed box with a 500w amp (nothing crazy) and 4 6.5'' mids (2 in front doors, 2 on back shelf) in a sedan.

with that small amp and single sub - at full amp gain the bass just drowns out the mids, yet often i see people with 2 or 3 12'' subs with the same size mids.

how can they use the full power of both those subs without drowning out the "music"??? or do i just have really quiet mids??
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Old 21st February 2008, 07:07 PM   #2
shagone is offline shagone  United States
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do you have an amp on your 6.5's? if not then you need one to keep up with the bass or you could just turn the gain down on your sub amp to balance things out. most people don't run the gains on any amp all the way up. the gain should be set according to the signal that is coming into the amp. the more undistorted signal you have coming in the less you need to turn your gain up and you get more headroom and undistorted output.
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Old 22nd February 2008, 08:23 PM   #3
jol50 is offline jol50  United States
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Yes, and some people just like to have loud bass to supposedly impress someone and don't care about how it sounds. Lots of people running 17w/ch out of their super high powered berylium phase capacitor fortified warp drive amplified HUs, and a big sub amp of 500-2,000w+....and it works as well as it looks like it would. I like to run a lot more watts on subs too but at least ample power on highs. Sometimes more just to make it cleaner but I never max them in a musical situation....mostly just to see how they are working/tuning/setting gains/for a kick/etc. I also like more capacity in subs because 20-30Hz takes a lot of power to make, and subs don't sound as good when sub system is stressed. They just need to be loud enough, but that is relative I guess.
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Old 23rd February 2008, 10:30 AM   #4
Dan2 is offline Dan2  South Africa
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i am running my mids straight off my frontloader - 50W x 4. it's not loud enough to make your ears bleed but there's enough power to distort the mids. Plus i really don't want to put more amps in the car.

I have a crossover question too:

i have a table (that came with my amp) that shows cap values for specific crossover frequencies. i decided to cross the mids over at 80Hz, because the sub is also set for 80 Hz. I could only get electrolytic caps. i put 1 cap one one speaker and left the other one with no crossover - they both sounded the same and distorted at the same volume, so am i trying to cross the speakers over too low???
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Old 23rd February 2008, 11:34 AM   #5
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Dan, Throw the 50x4 numbers out the window. A head unit, or frontloader as you say, with those ratings, may be capable of 8 or 10 watts per channel. Maybe a few more if it's a reputable, quality item.

It is my opinion that you are overwhelming the mids and highs with bass. It's tough to have a balanced system with amplified subs and the "main" speakers running off a head unit. And the distortion you hear may be simply from the head unit amp clipping, not from the mids being driven beyond their capability with clean power. If bad enough, this clipping can manifest itself in the form of high frequency, ear splitting distortion, and is a common problem with systems being driven with head unit amps. They simply are not designed for anything more than mid level volume. That's the reason dedicated amps exist.

And I agree with shagone, setting gain has to do with matching output from the head unit to input sensitivity of the amp. At a theoretical point of perfect match, the head unit will drive the amp to its rated power. Setting gain higher than that point not only does nothing productive, it's counterproductive, as it only increases distortion.
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Old 23rd February 2008, 04:14 PM   #6
jol50 is offline jol50  United States
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If you need to turn the HU up past half and have no amp....you need an amp on the high side. It will NEVER perform until you have one. You need bass in the fronts, but more midbass you might say. They can't produce 40Hz but they need to start at 80 where the sub leaves off. You need power to make 80hz, you need an amp or it will never work.

What I have read says max power that can possibly be made is 17wrms on 12v....or less. I would never run under 30wrms/ch in a car, you can pick up an old quality 30-40 x2 for near nothing that is not large. I prefer more like 75/ch minimum but do run choice amps that are smaller at times.

Your HU is just distorting like crazy, that is about all they are good for unless you only listen to talk radio or less than half volume.
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Old 24th February 2008, 09:01 AM   #7
Dan2 is offline Dan2  South Africa
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well i could actually put amps on all my speakers. the amp in my boot(trunk) is 1000w 4ch (don't know the rms output, but thats what is says on the amp) and i am only using 2 channels bridged for the sub. and i do have another 2ch amp (250w).

my 4 channel amp has a low\high pass filter - but the 2 ch only has low pass\ all pass. and how would i hook both amps up?? there is only 1 stereo RCA out on my HU.

i could hook the back speakers straight up to the amp - would that help??

i also don't have the worlds best mids in the car, the fronts are the one's that came with the car and the rears are (i think) 130W peak. so would it be worth putting the extra amp in???
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Old 24th February 2008, 03:24 PM   #8
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Dan, I would definitely amplify all speakers with a decent dedicated amp if possible. If you do not know what the mids are exactly, that's going to be a crapshoot. They may sound bad and distort regardless of what you do. If that happens to be the case, no way around it, replacement is a must if better sound quality is the objective. Some speakers are just bad, plus they could be damaged from previous use.

My idea of a decent dedicated amp is to have enough power at hand to give headroom to the user so that he is working his speakers to their optimum performance without running the amp to its ragged edge of performance.

Depending on what you use as your main speakers, they should definitely have some kind of high pass filter to keep out extreme low frequencies. This is another reason for audible distortion in these kinds of speakers.
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Old 24th February 2008, 04:05 PM   #9
jol50 is offline jol50  United States
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Yes, you need a HP on the amp or before. And you should have the best speakers in the car as your front stage. I think I would run the 4ch on the fronts and replace them, and put the smaller amp on the rears either at lower power full range or get a crossover of some type. Better yet get a sub amp and use the 4ch on all highs. Your front speakers will be 90% of the music you hear, they should be good speakers, and have the bass cut back with the HP because they are too small to make deep bass....but they need to make mid bass. If you get some; deaden and seal the inner door to help bass production if they are in doors. Until then you can try what works, if your rears are better put them on the larger 4ch then. He is right, much of the distortion will be from bass in the high side w/out a crossover. Those speakers can't make that low sound well and a small amp can't either.
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Old 25th February 2008, 12:24 AM   #10
shagone is offline shagone  United States
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all good advice so far.
will your rear 130watt speakers fit in the front locations? if so i would put them up front and leave the rears with nothing to let the bass in better and keep your focus on the front soundstage. you could use your extra 250w 2 channel amp with a y splitter on the rca's or with high level inputs and some passive crossovers or simple bass blocker caps on the front speakers or you could just use your existing 4 channel amp with the subs in stereo on the rear channels and the fronts in stereo on the front 2 channels. this should give you a more balanced and dynamic sound. i would try option 2 first since it's easier.

if your rears won't fit up front i'd say invest in a good component set. you will be very pleased.
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