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ppi deq 1/3 octave eq. hiss suppression ?

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Old 06-25-2006, 08:58 PM
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ppi deq 1/3 octave eq. hiss suppression ?

when l use my eq it puts out hiss, which is not audible during music play. at the show the judge mentioned that the hiss will put you back a point but move you ahead with better sound reproduction.
solution, is there anything l can use inline with rca cables after the eq and before the amp to remove hiss. thx for any suggestions
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Old 06-26-2006, 09:18 AM
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Are you sure it's comming from the PPI EQ? Could it be comming from anywhere else.

You will loose 5 points minimum in IASCA for noise.

I wouldnt recommend using noise suppresion equipment. Just remove the noisey processors.
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Old 06-26-2006, 11:05 AM
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the eq has a defeat switch. when turned of no issues. l guess l will just use it for rta
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Old 06-26-2006, 11:24 AM
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Couple of things to try,

1st. I dont remember if that EQ has both input and output level controls, but if it does its important to have both adjusted properly.. A poor system gain structure can result in a high noise floor. same goes for at the amp.

2nd. were is it located and how is it wired?
As a experiment only.. move the eq to right next to the amp.. wire the power and ground from the amp. and use the shortest rcas (1ft long for example) you can find to connect the eq to the amp. Try the sytem now. Is there noise? If the noise goes away then its probably wiring. If not also Disconnect the input rca's from the EQ, is there noise?

3rd, is the eq touching metal of the car etc? also check the screws, make sure there not touching metal either..

the ppi eq is a good piece, unless theres something wrong, it shouldnt be a noisey piece.

Last edited by VWmk5; 06-26-2006 at 11:28 AM.
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Old 06-26-2006, 11:48 AM
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eq is mounted on wood. the rca runs 1.5 ft and does not have any gain.
3 years ago a judge commented on having similar issues with his.

l have changed the rca to a different brand and tried using the -12 db attenuation.
lf the eq was picking up noise should it not always be present. when the defeat switch is engaged the hiss goes away.
if l turned down the amp gain l cant see that making a difference.
lm suprised that playing a **** bit track and hearing hiss that a device cannot rectify such a simple hurdle.

at a recent show a fellow competitor brought up the same issue about a proccessor and hiss and the judge said to overlook the hiss, this guy always places in the open class.
thx dave
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Old 06-26-2006, 03:08 PM
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I really like the PPI DEQ-230 but its reputation for some units being noisy kept me from going with it. Most are dead quiet, but not all, and from what I have heard the only fix is to find one that is quiet.
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Old 06-26-2006, 06:14 PM
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Ppi Eq

The PPI unit is very good in many ways but I found it (like pretty much anything you add to a system) adds noise. As far as analog automotive EQ's go I thought that it was as good as it gets (though I never used the ID). Since you've played with the gain adjust ... the only other quick fix would be doing a full sweep on each operating band of the EQ. The controls are not hermetically sealed so perhaps a sweep could clean up a noisy connection if some dirt or oxidation could be causing some noise in one of the frequency adjustment pots... also check the RJ-45 connector it can sometimes add noise.
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Old 06-27-2006, 01:01 AM
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good post^^^^! seen the same thing before.
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Old 06-27-2006, 08:54 AM
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gain and dash speaker placement

turned the gain on the amp to 35%, previously was 70%. my hu is 4v . to reach 100db the hu volume is played at 20-23 previously 15-19. the hiss is noticeably less, now its up to the judges ear.

will also try sweepin all the dials. speaker sounds more defined, using jl xr coaxial 5" on the dash.

note to all dash or pillar mount speakers.
had my dash speakers pointed towards the centre of the car. the open class winner has his pillar mount tweeters directed toward the centre of the winshield. l plan on trying the same. thx for the imput. dave
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Old 06-27-2006, 09:41 AM
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Originally Posted by surround sound

note to all dash or pillar mount speakers.
had my dash speakers pointed towards the centre of the car. the open class winner has his pillar mount tweeters directed toward the centre of the winshield. l plan on trying the same. thx for the imput. dave
Some tweeter play good on axis and bad off axis...its good to try new things but do lots of testing first to make sure its an inprovment!
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