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Why does my system sound terrible?


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jaugust 
Member - Posts: 7
Member spacespace
Joined: January 12, 2006
Location: United States
Posted: August 08, 2006 at 12:59 PM / IP Logged  

First off I have an '06 Scion TC.

I am using the stock headunit run into an Audio Control EQX and from there into a 50x4 Memphis amp and an 1100x1 Memphis amp.

The speakers in the front are Boston Acoustics Pro 60s and the speakers in the rear are just the stock Scion speakers. The sub is an Adire Audio Brahma 12D2 wired for 1 ohm.

The problem is that the sub is very quiet and the woofers in the doors are trying their hardest to play below 50 hertz, which isn't working out too well for them. The EQX won't let me adjust anything that goes to them below 120 hz, and Bostons crossovers seem to assume I wouldn't think of letting any low frequencies get to them to begin with so they don't do anything about it. The sub also refuses to play anything below about 40 hz, and occationally will produce a very horrible popping noise like its trying to excurt about 3 feet even though it's pounding out a massive 75 db.

I know I'm probably going to be told to get a real head unit, but if there is any way around that I'm open to suggestions.

DYohn 
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Joined: April 22, 2003
Location: Arizona, United States
Posted: August 08, 2006 at 1:17 PM / IP Logged  
Yep, I'll say the root of your problem is the stock HU.  I assume you are using the crossovers built into your amps?  Could also be they are setup incorrectly.  If you sub is "producing a popping noise" I bet your gain is cranked up.  It needs to be set correctly.
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jaugust 
Member - Posts: 7
Member spacespace
Joined: January 12, 2006
Location: United States
Posted: August 08, 2006 at 1:31 PM / IP Logged  

I've actually been wondering how to check the crossover settings on the amps. Memphis was nice enough to label one side of the knob as 20 and the other side as 20k with about 2mm of adjustment between. Am I going to have to take it to someone with an RTA and just check it with a test CD?

You are correct about the gain being pretty high, but even with the EQX maxed and the gain turned to about 75% the bass just isn't there.

Sadly in the end I think I'm trying to sew the proverbial silk purse. I was really hoping the EQX would take care of all my needs, but garbage in garbage out it would seem.

Anyway, thanks for info DYohn. 

Also, if anyone knows what voltage I should set the mcd1000 to for the Brahma, I can do that tonight to see if I still get the popping. The amp is 1100 watts and the speaker is wired to be 1 ohm, but I can check the exact measurement when I get home tonight if it makes a big difference.

DYohn 
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Joined: April 22, 2003
Location: Arizona, United States
Posted: August 08, 2006 at 1:52 PM / IP Logged  

Ohm's Law: Power=voltage squared times resistance.  1100 watts is delivered into one ohm at 33.16 volts.

How is your EQX connected to the factory HU?  Also, many factory HUs include EQ that cut off the lowest frequencies and emphasize other bands to compensate for shortcomings in the cheap factory speakers commonly used.

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jaugust 
Member - Posts: 7
Member spacespace
Joined: January 12, 2006
Location: United States
Posted: August 08, 2006 at 2:06 PM / IP Logged  

From the factory HU the speaker outputs are run into the EQX, which as far as i understand just amps them up and sums the front and rear to give you a sub output.

Can I use Ohm's law for the components also, or does it only work for the sub?

Also, about setting the crossovers on the amps. Is there any way to do that without an analyzer and a CD with some sweeps on it?

DYohn 
Moderator - Posts: 10,741
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Joined: April 22, 2003
Location: Arizona, United States
Posted: August 08, 2006 at 4:19 PM / IP Logged  

Ohm's Law is a universal electrical truth.  You need to setup the EQX first, then set the amplifier gains.

The EQX is a very powerful tool and can be difficult to get setup correctly.  First off, do you have the owner's manual?  Did you setup the input levels per page 13-15 of the manual?  Also, if you ar using the subwoofer output, the EQX has a built-in subsonic (or high-pass) filter set at the WAY too high value of 33Hz, which means it will not pass anything lower than 33Hz.  There is not much information down that low, but it could be part of the reason why you think you are missing something.  The sub output low-pass is preset to 90Hz.  SO, on your subwoofer amp, you'll want to disable the amplifier crossover, or set it to LP and the highest setting it has.  I suggest using the EQX full-pass output for your mains amp, and set the amplifier's crossover to HP (high-pass) and adjust the pot to about 90Hz.  When you set your amplifier gain, press the bypass button on the EQ.  Then when you adjust the EQ, be very careful using the boost.  It is better to cut than to boost.

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josh1979 
Silver - Posts: 320
Silver spacespace
Joined: July 03, 2006
Location: United States
Posted: August 08, 2006 at 5:55 PM / IP Logged  
 the scion head unit is a varible auto adjusting EQ if that make any sence. the more you turn the volume knob the radio is automaticly adjusting the EQ. if you have noticed you probley have beter bass responce at less than half volume  than you do at full because the radio takes the EQ down to keep you from blowing the crappy factory speakers and any thing on the other side of your radio will suffer from that. i drive a stock scion every day and listen to the crap it puts out. replace the radio and seeyou SQ increse by 100%
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josh1979 
Silver - Posts: 320
Silver spacespace
Joined: July 03, 2006
Location: United States
Posted: August 08, 2006 at 6:47 PM / IP Logged  
If you ever wondered what the DSP curves look like check this out. I connected an RTA (Real Time Analyzer) directly to the outputs of the OEM deck. The volume is set at 60 and all tone controls are flat. There is a disk with "Pink Noise" (sounds like static) playing. The far left of the display is labeled 25Hz and the far right is 20KHz. Each dot represnts 1/3 octave. There is a line through the center of the screen (horizontal) that represents 0 dB. Dots above this line are boosted and dots below are cut.
This is the electrical output of the deck and not the acoustic response of the system. Ideally, you would want the deck to be electrically flat (like an aftermarket deck would be).
XB Neutral:
Why does my system sound terrible? -- posted image.
XB Hear:
Why does my system sound terrible? -- posted image.
XB Feel:
Why does my system sound terrible? -- posted image.
XA Neutral:
Why does my system sound terrible? -- posted image.
XA Hear:
Why does my system sound terrible? -- posted image.
XA Feel:
Why does my system sound terrible? -- posted image.
TC Neutral:
Why does my system sound terrible? -- posted image.
TC Hear:
Why does my system sound terrible? -- posted image.
TC Feel:
Why does my system sound terrible? -- posted image.
bring back the rotary phone so i dont have to press 1 to proceed in english
DYohn 
Moderator - Posts: 10,741
Moderator spaceThis member has made a donation to the12volt.com. Click here for more info.spaceThis member has been recognized as an authority in Electrical Theory. 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: April 22, 2003
Location: Arizona, United States
Posted: August 08, 2006 at 7:51 PM / IP Logged  
Yep. no surprises.  Your first curve looks pretty typical for an OEM HU.
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jay-foe 
Member - Posts: 3
Member spacespace
Joined: August 08, 2006
Location: Canada
Posted: August 09, 2006 at 12:16 AM / IP Logged  

This helps me a lot, I had just posted about my HU dilemma prior to reading this. I was thinking of doing a similar style of set up (with not nearly the components mind you) but off the factory HU. Would the JL clean sweep actually fix all this the way it says it does on the website? How much was that Audio Control EQX? Are ALL HU's guilty of this or are some better than others? How can you find out (from literature, I don't have access to that kind of equipment)?

rocking subaru!!!
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