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ChrisK
05-17-2012, 02:50 PM
Just installed new Exile surf-style speakers with a Kicker ZX550.2 amp powering them. The speakers sound awesome when turned up, couldn't be happier. However, when I turn the tower speakers all the way down on my EQ, I can hear a hiss coming from them. When I turn the gain down on the amp it goes away but if I turn the gain down just to the point where I can't hear it, I then can't turn the volume up enough on the EQ enough (volume all the way up is only about where I would want half or 3/4 to be).

Any suggestions? Here's a link to some pics on the supra forum:

http://www.supraboats.com/bbs/showthread.php?9001-85-Supra-SunSport-Skier-PINK!/page6

dusty2221
05-17-2012, 03:09 PM
I didn't click the link yet, but which eq do you have?

philwsailz
05-17-2012, 03:18 PM
Hmmm.. It appears you have a Krypt EQ....


First - off, take the EQ out of the equation and wire the Kicker amp straight to the radio. Set the gain on the amp to get the volume you want based on the radio being at about 3/4 of max volume. Note, your head unit tone controls, (bass and treble) should be flat. With the setup this way and the radio turned down all the way do the speakers hiss?

If when the amp is wired straight to the radio there is no hiss and you can get your desired loudness, the hiss is coming from the EQ.

If when the amp is wired straight to the radio there IS hiss, the noise may be due to your perception that the tower speakers need to be louder, and you are compensating by setting the gain higher than necessary to try to get more than max power out of the amp.

At high volume do the speakers get all crunchy like your dads stock car stereo when it is turned all the way up? I ask this question somewhat gingerly, as I don't want to offend you, but I hear way too many systems where the owner has no clue that the amp is in hard clipping and the speaker cones are being bashed around so hard by the clipped square wave signal that the sound is more a buzz than music... A generation or two have grown up with no sense of what a clean non-distorted stereo sounds like; they simply don't know and think that crunchy sound of a heavily-clipped amplifier is what music is supposed to sound like when it is loud...


I have a feeling that the hiss is going to go away when you remove the EQ from the signal chain. Every piece of electronic gear you put between the CD or iPod and the speakers has a pre-amplifier gain stage, and all pre-amps make some noise. Some are worse than others, but know that the better the gear, the lower the noise generally. Your radio has a preamp stage and it makes a little noise. The EQ has a preamp gain stage, and it amplifies the little bit of noise in the radio, plus it adds its own. As you experienced with the amp, its gain stage will add noise when turned up, so that is a good example. For every part of the signal chain you want gains set as low as possible while set just high enough to give you rated power output from the amp.


Unfortunately, sometimes you find that a piece of gear is just inherently noisy, and a HLCD tower speaker is going to be very revealing of that. There is not going to be much you can do short of finding out where the noise really lives, and then either eliminate it by removing the offending piece of gear from the system, or replacing it with a product that has similar function, but better performance and signal-to-noise specs.

Phil
Kicker

wolfeman131
05-17-2012, 03:29 PM
Hmmm.. It appears you have a Krypt EQ....


Phil,

Awesome write up, as always, but really your explanation could've just read as above. . .

Chris, no offense meant towards you in my statement.

Jet
05-17-2012, 03:40 PM
Why do i feel worried now??

EarmarkMarine
05-17-2012, 04:23 PM
Here is a quick check. If the amplifier is run at a 4-ohm load the input gain may be set a little higher...for 2-ohm load a little lower. If the EQ has strong preout voltage this will reduce the amplifier input gain. So disconnect the RCA inputs to the amplifier and set the amplifier input gain at an anticipated 35 percent to reach full power in this scenario. When the amplifier is turned on any thermal noise you hear is totally owned by the amplifier and I would expect it to be there but minimal. Any additional noise you hear once you plug back in the input RCAs (please power down before un/plugging/in RCAs) is totally owned by the components upstream in the signal path or a mismatch in the interface between the upstream components.

David
Earmark Marine

ChrisK
05-17-2012, 06:03 PM
Phil, thank you for the detail, however I don't have a radio/HU. My source is my phone, which goes aux in to the EQ, then to the amps. Also, I know what you mean by not understanding what loud is supposed to sound like, but it truly wasn't loud enough.

Wolfeman, my system is an on-going project that can't be completed all at once with my budget, can't wait to get the whole thing dialed in with high-quality stuff!

David, thanks for the suggestions, I'll try that out.

dusty2221
05-17-2012, 06:08 PM
You can use the same method he suggested with the wiring harness coming out of the Krypt, I believe.

philwsailz
05-17-2012, 06:15 PM
Phil, thank you for the detail, however I don't have a radio/HU. My source is my phone, which goes aux in to the EQ, then to the amps. Also, I know what you mean by not understanding what loud is supposed to sound like, but it truly wasn't loud enough.

Wolfeman, my system is an on-going project that can't be completed all at once with my budget, can't wait to get the whole thing dialed in with high-quality stuff!

David, thanks for the suggestions, I'll try that out.

iPhone? I know of an ampified controller for iPod and iPhone with preamplifier outputs...:cool:

Regardless, the use of the phone might explain it further. You have a limited voltage out of the headphone output of the phone. A suggestion would be to use a line driver either in front of the Krypy EQ or in place of it. As an example, the Kicker ZXM-RLC will double the voltage from whatever is connected to the front end. With more voltage going into the amp you can turn the gains down and get the same power out. Gains down as you figured out will be quieter with everything turned down..

There are other options, some a lot more money. Bottom line, you just need a hotter signal going to the amplifier.

Zat make sense?

Phil
Kicker

wolfeman131
05-17-2012, 06:32 PM
There are other options, some a lot more money.

HAHA!

Now me & Phil are BOTH spending your money. :)

ChrisK
05-17-2012, 06:34 PM
Yes it does, awesome to be a part of a forum where people drop knowledge like this.

Most of this stuff is over my head so I'm going to ask a dumb question. A lot of the time I'm playing music through Pandora and I know the app has a setting where you can increase the quality of the music but if you do it drains the battery quicker. If I have it on the poorer quality setting could that be a culprit of the hiss? Again, probably a dumb question.

Also, if I get one of these so-called line drivers, will a standard aux male-to-male cable be sufficient to carry the power? Or do I need to purchase one that is higher quality?

It is an iphone, btw, don't know if that matters.

bbuhtz
05-17-2012, 06:49 PM
Just installed new Exile surf-style speakers with a Kicker ZX550.2 amp powering them. The speakers sound awesome when turned up, couldn't be happier. However, when I turn the tower speakers all the way down on my EQ, I can hear a hiss coming from them. When I turn the gain down on the amp it goes away but if I turn the gain down just to the point where I can't hear it, I then can't turn the volume up enough on the EQ enough (volume all the way up is only about where I would want half or 3/4 to be).

Any suggestions? Here's a link to some pics on the supra forum:

http://www.supraboats.com/bbs/showthread.php?9001-85-Supra-SunSport-Skier-PINK!/page6

Sounds like it is just your tower speakers with the hiss from your discription. Do your in boats have the hiss sound as well? If its just the tower speakers I'd think you would be able to narrow it down to either the EQ, EQ and amp gains, or some wiring, either cheaper RCAs to the tower speaker amp (550 i believe). I doubt that it would be your phone if you are not experiencing the hissing coming from the other speakers (inboats). Also could try just flip flopping the RCA outs on the EQ (inboats swapped with the tower) and see if that makes a difference. See if that changes the hissing from the towers to the inboats. Good luck, I had the hissing last year just from the tower speakers but it ended up being a bad HU and you don't have one, so that rules that out.

EarmarkMarine
05-17-2012, 07:19 PM
Listen to what Phil said about the line driver after the iphone and before the EQ. You can bet that EQ has hiss and is the primary culprit. 'Hiss' is a matter of a ratio between the EQ's noise floor and the music material. The iphone has very little voltage which places the impetus for increased gain mostly on the EQ. If a cleaner line driver takes most of the gain responsibility then much less is demanded of the next gain stage which is the EQ. I can definitely see how this would produce less noise.

David
Earmark Marine

ChrisK
05-17-2012, 08:08 PM
Just messed with the RCA's. The hiss went away when I disconnected the two RCA's designated for the tower from the back of the EQ. So this obviously means the culprit is the EQ, correct? Would a line driver solve that problem? Would a higher quality RCA between EQ and tower amp help the problem?

Thanks again guys.

EarmarkMarine
05-17-2012, 09:26 PM
The RCA cable isn't contributing to the hiss.

ChrisK
05-17-2012, 10:46 PM
I know, disconnecting the RCA from the tower outs revealed that the problem is the EQ, correct?

jmvotto
05-17-2012, 11:09 PM
Chris, it's not the brand of eq it just the addition of one with hlcds.i had a ws420 on the old boat and same deal. I believe the Krypt 4200 has a adjustable gain on it for the line driver input may try adjust that.

http://www.moomba.com/msgboard/showthread.php?12084-ws-420&highlight=hiss

philwsailz
05-17-2012, 11:19 PM
I know, disconnecting the RCA from the tower outs revealed that the problem is the EQ, correct?

Ding ding... We have a winner.

Back to my last post: while I am not going to point simply to the EQ as the culprit, it might be, (Wolfe, I know what you are thinking) but bottom line, it is at best passing through the voltage from your iPhone and not providing any amplification while at the same time is contributing at least some noise at its noise floor threshold.

A basic head unit will deliver 1-2 volts out at the RCA line outputs. A high-end head unit might deliver 5 or even more. Your iPhone might be putting out a quarter-volt. There just is not enough difference between the output sound from the phone and the noise floor sound of the EQ.

With a 2x line driver you theoretically will increase the voltage from a quarter to a half volt. Still not a lot but that is 3dB. 3 dB right Dave? As a result you can lower the gain of the amp by a corresponding 3 dB and in a perfect math world means you lower the relative hiss by half.

I am really teetering on the line here, so I am trying to be as objective as possible. Kicker makes a device that essentially makes your phone a source unit and has the voltage output to keep amp gains lower than you currently set them. As a bonus, the audio comes out of the 30 pin connector, and charging goes in. When plugged in your phone won't go dead.

The device is our PXi50.2. I will stop there as any more information takes my objective statements to subjective; something I avoid. Google it or ask more questions here but know it might be a solution that will allow you to keep using your current EQ.

Hope that helps

Phil
Kicker

philwsailz
05-17-2012, 11:29 PM
Most of this stuff is over my head so I'm going to ask a dumb question. A lot of the time I'm playing music through Pandora and I know the app has a setting where you can increase the quality of the music but if you do it drains the battery quicker. If I have it on the poorer quality setting could that be a culprit of the hiss? Again, probably a dumb question.



Nope. Low-Q will sound really compressed and AM-Radio-sounding but it is a difference in signal quality, (resolution) as opposed to signal amplitude, (voltage).

Phil
Kicker

ChrisK
05-18-2012, 03:38 AM
Thanks for the help, still interested to hear everyone else's opinions!

lsvboombox
05-18-2012, 09:46 AM
I have a different setup. But if i plug my ipod into my mb quart with the regular 1.8mm aux plug i get hissing. After i ordered the mb quart ipod interface cable no hissing.

Are you using a 1.8mm plug to rca's. Or the ipod plug(bottom of ipone) to rca's

jmvotto
05-18-2012, 10:02 AM
Is the iPhone plugged into a 12v outlet whole connected to the front 1/8 input plug. I did this playing Pandora from the driver side 12v plug not battery and hot a buzzing noise, ran on battery and it was fine.

Sent from my ADR6300 using Tapatalk

ChrisK
05-18-2012, 12:21 PM
I'm just using the standard 1.8 aux plug, male-to-male and the phone isn't connected to a power source.

jmvotto, where is the gain on the EQ? I'm not seeing it for some reason?

bbuhtz
05-18-2012, 12:23 PM
I'm just using the standard 1.8 aux plug, male-to-male and the phone isn't connected to a power source.

jmvotto, where is the gain on the EQ? I'm not seeing it for some reason?

Should be 2 little nobs ontop of the EQ... you remove the plastic plugs to access the gain settings. You will need a small screwdriver to adjust them.

philwsailz
05-18-2012, 12:30 PM
Should be 2 little nobs ontop of the EQ... you remove the plastic plugs to access the gain settings. You will need a small screwdriver to adjust them.
If there are input sensitivity at output gain adjustments on top absolutely this is a first step! It hopefully will give more output and allow you to turn amp gains down. Best of all the cost is FREE!

Good call bbuhtx-

Phil
Kicker

jmvotto
05-18-2012, 01:50 PM
Should be 2 little nobs ontop of the EQ... you remove the plastic plugs to access the gain settings. You will need a small screwdriver to adjust them.

What he said.....:)

You may have to unmount the eq from the brackets to get to them.

bergermaister
05-18-2012, 04:20 PM
Another possible test for you Chris (if you're not using one of these already) is to switch from the mini audio output on the ipod to the data output using an adapter.

I picked one up like this- http://www.buy.com/prod/usb-3-5mm-aux-audio-data-charger-cable-mini-universal-usb-car-charger/219021203.html and the sound quality is definitely better. Less noise on the line.

Mine doesn't like to charge the phone while plugged in but I can live with that with all the other chargers available.

ChrisK
05-19-2012, 11:30 AM
Berg, I don't think it has anything to do with the cable I'm using, because the hissing is still there when the phone isn't plugged in...

Also, I tried adjusting the gains on the EQ all the way down, and the hissing was still there. When I switch the RCA's on the back around (put the tower RCA's on the boat outputs) the hissing gets slightly better, but it's still there. So, I think I've determined it's just bad outputs? A by-product of buying the cheap alternative. Gonna have to live with it I think...

jmvotto
05-19-2012, 11:45 AM
so the hiss, it moves to the inboats when the rca's are swapped around.

philwsailz
05-19-2012, 12:47 PM
Turn the gains UP on the EQ and DOWN at the amp and see what it does. You might still have a freebie solution.

Phil
Kicker

ChrisK
05-19-2012, 08:48 PM
JM, I didn't try plugging in the boat speakers to the tower outs, so I don't know, I can try that.

Phil, I'll try that as well, thanks.

jmvotto
05-19-2012, 10:59 PM
JM, I didn't try plugging in the boat speakers to the tower outs, so I don't know, I can try that.

Phil, I'll try that as well, thanks.

If the hits moves to the cabins it's that output if not its the gain on the amp to the hlcds.

ChrisK
05-25-2012, 03:34 PM
Just following up on this...

I'm extremely happy to say that I just turned the gains on the EQ all the way up and the gains on the amp down a bit and the hiss went away, speakers sound fantastic!