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Audio Control Dqs, Eqs, And The Epicenter-Ipod Bass Mia?


WakesetterE

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Deephaven,

It was just an example but you can't disprove Ohm's Law, however, you can misapply it. Ohm's Law assumes that you have an unlimited supply so when the formula is applied to most audio amplifiers for instance it can't be applied with such simplicity. Its much the same with speaker impedance since its not linear so designing a passive crossover based on fixed values will often produce a very bad sounding speaker. The point I was making is that there are often additional layers of analysis that go into making conclusions. Those things assumed as fixed are not always so. Even a brilliant engineer can overlook some of the influences if its not his field of applied science. So in anything there comes a point after a little explanation and substantiation when we might tolerate a few differences in opinon and let it be.

David

Earmark Marine

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Bottom line is the lower you are able to keep the gains on the amp the better off you'll be, preamp voltage allows that to happen. This lowers the noise floor, which is there on any boat system. You don't have to agree but doesn't mean it isn't true. BTW I never said a line driver was the solution to his problem.

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It was just an example but you can't disprove Ohm's Law, however, you can misapply it.

Sorry, my sarcasm didn't come across. I knew what you were getting at.

Bottom line is the lower you are able to keep the gains on the amp the better off you'll be, preamp voltage allows that to happen.

Instead of some unsubstantiated claim please explain why you think that is the case and in what situation(s) its true. Outside of the "crap amp" option I already provided.

This lowers the noise floor, which is there on any boat system. You don't have to agree but doesn't mean it isn't true. BTW I never said a line driver was the solution to his problem.

In any case outside of the amplifier being the source of the noise this will not be the case. If there is noise on your pre-amplifier outputs the amplifier will amplify it. The best method for removing noise is to go to the source. Same thing with a line driver. A line driver is gain block. It takes an input and makes it have more voltage on the output. Guess what an amp does? Exactly why using one to "lower the gain" will do absolutely nothing for the OP.

And in no way did I take what you said as recommending that the OP use a line driver.

Perhaps I should phrase this in a question to make it easier for you guys to refute.

Very simple case: Two headunits, both playing a sine wave. Output is in voltage, but for simplicity let's convert it into equivalent dB as then the speaker is out of the equation. One has a 'speaker' output of 50dB the other 56dB. Each has equivalent noise which as referenced per the signal 50dB has 10dB of noise and the 56dB has 16dB of noise. Now we apply a gain block to get the level up to 100dB. One amp required 50dB of gain the other 44dB both yielding a noise response now of 60dB. Obviously one amp needed the gain to be 6 dB more than the other but imagine that the noise performance is the same. Curious why you would think differently.

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Sad thing is, the OP has a noise problem that no one here is helping. First thing I'd do is start replacing/removing portions of the music chain to see if it was the h/u that is the cause and then replace the troubling piece.

Pretty sure I already stated that in post #5.

As far as your posts regarding input voltage vs. output voltage, that's all pretty much common sense. The OP didn't ask if a line driver would make his system louder, and I didn't read that anyone said it would (of course I'm on two hours of sleep) so why get into all that?

Simple test for noise floor: put HU on aux input with the ipod plugged in and hit pause. No sound shoud be coming out of the speakers in an ideal setup, right? Now go ahead and turn the gains from all the way down to all the way up and see if the hiss gets louder or not. If it doesn't get louder, it may be in the output stage of the amps. If it does get louder with more gain, eliminate the head unit by goind straight from the ipod into the amps with a 1/8th to RCA chord and do the same test on pause.

Good luck.

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Ok, although it was 35F here, I climbed aboard the boat to do a few tests with the EQS. I had a few problems last summer that I wanted to address. One issue was that at 100% volume off the Fusion HU, the output sounded less clear than I wanted. I already had the amp gains up about 1/2 way. When I cranked the amp gains up is when I recognized a higher than normal noise floor at lower volumes on the HU. It wasn't terrible, just I wanted better.

Thats when I researched the pre-amp output power on the Fusion radio (MS-IP500W) and found it to be advertised to be 2 volts(may be less?). I think running the HU at 100% was likely inducing some distortion from the deck itself. I limited the output to about 80% and it seemed to clean it up, but output was down also.

I read about the EQS, with its line drivers, and 6 channels, the EQ was really only a bonus. It has line level lights that allow you to adjust the inputs/outputs to 2 or 5 volts out at peaks. I figured with the line drivers, I could reduce the amp gain, leave the deck output at 80% max, and still drive the amps to higher volumes. So, i hoped for an easy fix as the HU sits in a custom fabricated bracket made for it mounted under the dash with the sub built around it. Plus, my sub sounded a little off, a little boomy, and i thought some EQ could help.

When I got into it, I discovered the sub output has a HU crossover set at 80 hz. I disabled that and i think the bass sound improved, as i was already crossing the sub at 150hz at the amp. Both of those at one time wasn't working well together.

I temp installed the EQS, and tried to adjust the line levels on the EQS so at peaks they were at 5 volts. I had the amp gains all the way down as the manual indicates. With various music, I couldn't get the obtain 5 volts output, with the deck limited to about 80%. 2 volts output from the EQS was all i could get. I realize i could turn up the amp gains.

So, its looking more and more like the Fusion pre-amp output is really low, or not very clean at 100%, and low.

I suppose at this point the Fusion may have to walk the plank.....I really liked its 100% sealed waterproof chassis, multiple channels pre amp out, and the ability to carry an I pod inside the unit to play, control, and charge it.

Suggestions on HU's that survive in a boat that sound great? I was an Alpine fan in the 90's....

Oh, and I wanted to say I appreciate all responses, even when all don't agree. So often the way things are suppose to work doesn't happen for reasons unclear and experience is the key.

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One issue was that at 100% volume off the Fusion HU, the output sounded less clear than I wanted. Thats when I researched the pre-amp output power on the Fusion radio (MS-IP500W) and found it to be advertised to be 2 volts(may be less?). I think running the HU at 100% was likely inducing some distortion from the deck itself. I limited the output to about 80% and it seemed to clean it up, but output was down also.

FYI if you buy a new deck, there are VERY FEW that will run at 100% volume with no distortion. 80% is a good estimate for max output. Have you tried direct from ipod to amp direct just to see what the hiss does? Or do you have any old '90s Alpine laying around to plug in and bench test? :)

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99% of the time I'm playing an ipod or iphone. I stream off my HTC pandora also. No CD's, seldom radio.

I havent tried direct to amp yet...raining and 35F here today!

This sounds cheesy but I avoided the 3.2 and others like it as I didn't feel they would fair well in a marine environment, and mainly because I have others that operate the boat. i need one simple, crank it to the max knob, i cant blow up the speakers knob or alter the sound or I'll find all the knobs wide open!Thus the EQS, mounted away from others fingers out of the wet.... :) Shooting for simplicity.

May be even no deck and some type of bluetooth connection to the smart phones.....

Edited by WakesetterE
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99% of the time I'm playing an ipod or iphone. I stream off my HTC pandora also. No CD's, seldom radio.

I havent tried direct to amp yet...raining and 35F here today!

This sounds cheesy but I avoided the 3.2 and others like it as I didn't feel they would fair well in a marine environment, and mainly because I have others that operate the boat. i need one simple, crank it to the max knob, i cant blow up the speakers knob or alter the sound or I'll find all the knobs wide open!Thus the EQS, mounted away from others fingers out of the wet.... :) Shooting for simplicity.

May be even no deck and some type of bluetooth connection to the smart phones.....

I'm in dallas too and yes, the weather sucks today. I would not be too concerned about an EQ in a marine environment. I have not heard of anyone coming on here and talking about toasting their EQ due to water. The Three.2 has one bigger volume knob on it.

I thought it would also be trouble having other knobs available to the people in my boat...but it was not a problem at all. Just take a pic of the setting with your phone and if they get messed up - you have a blueprint to quickly get them back in check.

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E,

Preamp voltage specs are about as reliable as amplifier wattage specs. You never know based just on the specs alone. A legit 2 volts should not be an issue, especially if you are using an EQ that has considerable voltage out. Now, if the HU has significant surface noise that would be a different story. So before wholesale changes you must isolate exactly where most of the noise is originating from. For me its much easier as a process of elimination to begin with the last electronic component in the signal path and then work backwards towards the source one component at a time. This way one problem cannot mask another problem. Its really easier to isolate.

85 percent is generally the average setting on average program material when a HU output will begin to demonstrate soft clipping. The better way to go is to determine exactly what that setting is in reality with each individual HU. Plus, the strength of your source, such as an external ipod, can vary the maximum setting of the HU.

David

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As far as your posts regarding input voltage vs. output voltage, that's all pretty much common sense. The OP didn't ask if a line driver would make his system louder, and I didn't read that anyone said it would (of course I'm on two hours of sleep) so why get into all that?

Not at all the point of my post. i was showing they'd have equal noise, not increased output. The preface was he wanted to lower his noise floor and was wondering if a line driver would help. Generically speaking if it isn't the amp then it won't which I showed with very simple math.

Simple test for noise floor: put HU on aux input with the ipod plugged in and hit pause. No sound shoud be coming out of the speakers in an ideal setup, right? Now go ahead and turn the gains from all the way down to all the way up and see if the hiss gets louder or not. If it doesn't get louder, it may be in the output stage of the amps. If it does get louder with more gain, eliminate the head unit by goind straight from the ipod into the amps with a 1/8th to RCA chord and do the same test on pause.

That test isn't quite simple enough. Start at the end. Unplug the RCA's from your amplifier and turn up the gain with nothing connected to the input. If the noise exists it is your amplifier. If it doesn't, its time to go up stream and find it. Whatever is up stream from that point on will be amplified equally through any gain block whether it be the amplifier or a line driver.

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Preamp voltage specs are about as reliable as amplifier wattage specs. You never know based just on the specs alone.

Another valid point. Many 5v decks are distorted beyond comprehension when they eclipse 2v. Change that to a 2v deck that can actually output 2v without audible distortion and even by any other argument you gain nothing with the 5v "spec"

Now, if the HU has significant surface noise that would be a different story. So before wholesale changes you must isolate exactly where most of the noise is originating from. For me its much easier as a process of elimination to begin with the last electronic component in the signal path and then work backwards towards the source one component at a time. This way one problem cannot mask another problem. Its really easier to isolate.

85 percent is generally the average setting on average program material when a HU output will begin to demonstrate soft clipping. The better way to go is to determine exactly what that setting is in reality with each individual HU. Plus, the strength of your source, such as an external ipod, can vary the maximum setting of the HU.

Exactly my point by measuring amp alone...although pretty sure the Fusion smells a bit in this regard.

On an aside, I've measured headunits that have no visible waveform distortion on an oscilloscope all the way to 100%, but I've also seen them go to all hell at 50% (dial level, not output voltage). Wasn't setup to truly measure distortion, but at least it was apples to apples.

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