DEH-P780MP + RF 25 To Life Punch 75, bad combo?

[741rms]

I recently purchased and installed a Pioneer Premier DEH-P780MP, to replace my old DEH-P3500.. mind you, the old head unit worked great and sounded great for what it was.

I installed the DEH-P780MP and got a rumbling through the sub without music playing, I would get noise when pressing buttons or turning the volume up or down, it wouldn't get louder or quieter, the volume of the noise was consistent. Stripping the outer sheilding on the RCA's and grounding that shielding to the head unit appears to have solved that problem, but I'm faced with a new problem;

The gain on the amp, assuming there are three positions DOWN, MID, HIGH (for example only as there are no real set positions), will not cause the sub to become louder until it reaches almost all the way to the highest setting, and this head unit is suppose to have 5v max (2.5vRMS?) pre-outs.. When you reach a certain point while adjusting the gain, the volume jumps from almost silent to loud..

I'm not entirely sure if the problem is within the amp and I never noticed it because my DEH-P3500 has something like 2v (max) pre-outs and the gain needed to be nearly all of the way up to get decent sound, or if this new head unit is defective?

To add another twist to this issue, I've also used the following models with these exact issues, both of which were nearly solved with using a ground loop isolator and/or grounding the RCA shielding to the head unit chassis;

DEH-P5900IB

DEH-P6900UB

I also want to note that with the gain adjusted nearly all of the way up on the amp, if i crank the volume on the stereo (with the sub adjustment at +6/-12 slope/63Hz cut-off) it gets loud enough to make my vision blurry (single 12" Diamond D6 ported @ 34Hz @ 1.9cu/ft before displacement)... but the volume has to be so insanely loud that my ears hurt from the components up front, and the only middle ground to resolve this is to turn them down or turn the volume down on the head unit and go without bass =/

Can anyone shine some insight into this issue? It's something I thought was an issue with how Pioneer was building their newest units, but I'm starting to think there's something funky about this amp.. I'm under warranty through Rockford, so sending it in for repair shouldn't be a huge problem..

I guess it should also be known that I don't get any of these weird noises through the components (that I've noticed), only through the sub.

I've also gone over my grounding point for the amp, used a dremel and shaved the metal down even further and replaced the original bolt, shortened the ground to 12", tried a new set of RCA cables..

I'm open to ideas!

My equipment (maybe this will help?);

Pioneer Premier DEH-P780MP

Polk DB6500 Components (front stage)

RF '25 To Life' Punch75 bridged @ 4 ohms

Diamond D6 12" D2

4awg power/ground

2 channel RCA's, run on the opposite side as the power/ground

16awg REM wire

The sub has 8awg run internally, as well as from the amp to the box..overkill, I know..

Hope I've been descriptive enough, and I look forward to your reponse(s) //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

EDIT: I didn't think of it before, but, when I turn set the filter on the amp to LPF (low pass filter), it's louder than turning the filter off.. you'd think it'd be the other way around, right? At least, that's my experience.. when I use to run a DEH-P860MP, no matter what amp was installed when the LPF was on the sub(s) were quieter, when it was off they were louder.. probably because the head unit has the built-in DSP, as does the DEH-P780MP.

I've also, since writing this, read a post on SSA as well as RF Forums (seems to be from the same guy) saying his Punch 150's and 45's (all 25 to Life series) do basically nothing until the gain is set to around 3/4 of the way up.. could this be a serious flaw in workmanship? //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif

I'm off to work now, but any help is appreciated //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

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[741rms]

Anyone?

EDIT:

I contacted RF's tech support line and he said the the pot(gain knob) is probably a little off, and if the amp isn't getting too hot, and if it's still working that it's fine.. what do you guys think?

 

[hemi=22s 10+ year member]

try running the sub amp with the rear or front output whatever ur component amp is hooked up to see if u still get the noise to isolate if its the sub output or the amp

 

[741rms]

I don't have a amp for my comp. speakers, just head unit power, and I've tried using a different set of RCA outputs without success. //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif

I believe the problem is the Gain control on the amp is defective in some way.. I believe this for two reasons;

1.) I found posts on SSA and RF Forums where someone was having this exact issue with his 25 To Life 150's and 45s.

2.) The RF tech I spoke to earlier today made it sound like this Gain issue was fairly common.. not in so many words, just the way he said 'the pot is probably off a bit'.. pot, as you probably know, is the type of knob that is the gain control.

I don't know that there's anything I can do other than replace the amp to resolve this issue, provided the issue is, in fact, the Gain knob... if I send it it, they'll probably send it back saying it works fine.

I'm still open to ideas as to what the problem may be.. It's not set in stone that the problem is the Gain knob, that's just the most probable explanation at this time.

 

[hemi=22s 10+ year member]

pioneers are nototrious for sound in the shitty rca preouts though i have never had a problem with my 780 or 980 or any of the units that had the removable plug rca's

good ground behind the deck

do ya got a different amop to try

i would still plub it in to the rear outs see if ya get the noise still to rule out the sub outs arent bad

 

[741rms]

pioneers are nototrious for sound in the shitty rca preouts though i have never had a problem with my 780 or 980 or any of the units that had the removable plug rca's
good ground behind the deck

do ya got a different amop to try

i would still plub it in to the rear outs see if ya get the noise still to rule out the sub outs arent bad

I've got the head unit grounded directly to a paint-less section of the transmission hump (though, there isn't a transmission in that hump, since it's a FWD 5-speed //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif).

I've also tried to use a different set of RCA outputs, the rear outputs I believe.

My old DEH-P3500 had no problems with noise in the RCA outputs, but all of the other units I listed in the original post have.. and the only real problem now, since I've grounded the outter shielding of the RCA's and gotten rid of that rumbling noise, is the Gain knob on my amp. I'm not sure what to make of it.

If all else fails, I might pick up a Cadence TXA-750D and send my Punch 75 in for repairs.. see if they'll replace the Gain knob.