# BillP: Did you need a Hi/Lo converter or ground loop isolator on your audio upgrade



## nealh (Oct 4, 2003)

I got around to upgrading my audio..I had the install done by a very high end installer...

Front speakers are MB quart PCE 213 5.25 component speakers..premium line
JL audio 500/5
remote bass control installed

waiting to get my sub(JL 10W3V2)...I had them cut out the dsp cutouts to allow bass into cabin

Anyway..I had them connect the HU directly to JL audio amp with no hi/lo as it was recommended by some at RF not to do this as it could diminsh audio quality...

well they claim this is the reason I got an alternator whine...they recommend a hi/lo converter that can also be a ground loop isolator as well

They also feel the MB crossovers are picking up the noise and need to be wrapped in shielding material now too

Did you get any alternator whine..very noticable with talk radio and with radio off

als ogot a white noise that you hear from the speakers when radio is off but car turned out..I guess this is the amp turning on...they connected the amp to white wire..amp is not set too remote sensing


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## Dr. Phil (Dec 19, 2001)

The whine should be cut down on if not eliminated with a convertor. In my Honda the I kept the stock HU in I used one and was pleased. The passive crossover protection would not jurt either.

How do you like the JL amp? I am thinking of using it myself :eeps: I go this Saturday to have my car speced out and have 2 options in mind.....kill the H/K "subs". tap the source in the back and add a sub enclosure w/ a 250 mono amp * OR * take all the speakers out and rebuild completely with the 500/5 amp :bigpimp:


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## nealh (Oct 4, 2003)

I am no audiophile...but I did notice right after the install the sound was clearer, louder and brightner...I think the JL audio amp is very nice but not sure how to easy tell how good or bad...I was told by my installer that the gains are not nearly maxed and I have plenty of headroom...

I was not looking for loud but clear sound..right now I have no low end as the tweets and mid are blocked from providing much since the amp was used to prevent the low freq from distorting the component speakers..Once I have the sub in place I can say more but I am sure I need no more power....

It is a large amp but it is a single component which was a plus to me...


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## BillP (Jan 4, 2002)

nealh said:


> Did you get any alternator whine..very noticable with talk radio and with radio off


I do not have hi/lo converters in my install: JL 500/1 for the sub and a 300/4 for the mains. I *did* have alternator whine when I originally installed the equipment. However, I eliminated 90% of the whine when I cleaned up my uber-crappy original wiring (lots of loops of excess wire). The last 10% of the whine was due to the fact that I had the 12V trigger wire running alongside the signal wires. After I rerouted that wire around the other side of the amp, the whine was gone.

Other pertinent facts:

* Direct grounding to the negative terminal of the battery
* Short-as-possible power and ground wires
* 8gauge wire used for both power and ground
* Power and signal wires were separated as much as possible
* Cheapo interconnects (low-end Monster and Ratshack)

Cheers,
Bill


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## Jon Shafer (Dec 15, 2001)

Merry Christmas Bill!


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## jun (Oct 10, 2002)

BillP said:


> I do not have hi/lo converters in my install: JL 500/1 for the sub and a 300/4 for the mains. I *did* have alternator whine when I originally installed the equipment. However, I eliminated 90% of the whine when I cleaned up my uber-crappy original wiring (lots of loops of excess wire). The last 10% of the whine was due to the fact that I had the 12V trigger wire running alongside the signal wires. After I rerouted that wire around the other side of the amp, the whine was gone.
> 
> Other pertinent facts:
> 
> ...


I also have the jl amps 500/1 and 300/4. IThe fronts are diamond Audio HEX series and the rears are Diamond Audio coax. I have 2 jl audio 10w6v2 subs. I have the alternator whine right after the install as well as white noise. the installer was saying that he would have to get me a PAC 2 interface for me. The installer is a very well known installer in the area. I came to know him when I saw one of his cars in the magazines.


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## nealh (Oct 4, 2003)

jun said:


> I also have the jl amps 500/1 and 300/4. IThe fronts are diamond Audio HEX series and the rears are Diamond Audio coax. I have 2 jl audio 10w6v2 subs. I have the alternator whine right after the install as well as white noise. the installer was saying that he would have to get me a PAC 2 interface for me. The installer is a very well known installer in the area. I came to know him when I saw one of his cars in the magazines.


Thanks BillP

It seems to me that a high end installer should be able to wire the car without whine...BillP admits it was crappy wiring job..too many loops, poor grounding etc...

I am very disappointed in my installer but afte talking to the VP they are going to fix and try to do so without adding cost

The white noise clearly is the result of the amp coming on as the key position is changed...it is very low volume noise and can not be heard after the radio and engine are on...

The whine totally sucks .....

BillP are you using remote sensing to turn on the amp or did you get white wire directly into the amp so when the ignition is on the amp turns on

I would love to toy around with amp settings since the installer is going to work on the car but the installed the amp so the controls are away from me and the amp is positioned on the bracket so you ca nnot see or reach some without taking the bracket down


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## BillP (Jan 4, 2002)

nealh said:


> Thanks BillP
> BillP are you using remote sensing to turn on the amp or did you get white wire directly into the amp so when the ignition is on the amp turns on


Sorry for not replying earlier, I've been on the road. Unfortunately, in my wife's stock stereo Volvo and not my car. 

I am using the remote trigger wire from the head unit (available in the back, the white wire, I believe). I originally had it wired that way, then something happened and the remote 12V wire was ALWAYS hot and it drained the battery. I then changed the wiring to some other switched wire I found in the back (for the phone or NAV perhaps, three cheers for multimeters!) After a separate problem with the head unit requiring replacing it, the 12V remote wire worked again so I put it back to the original configuration.

BTW, finding and solving alternator whine in car stereos is a black art. Never make the assumption that a professional installer is better at eliminating them in an E39 than someone who has tons of experience with the car. That isn't a slam on your installer, just the fact that even an experienced installer has probably only worked on a small number of E39s. It is also important to note that there are multiple ways of solving the problem, both passive (routing wires, checking grounds, ...) and active (boxes like the hi/lo converters that isolate grounding problems. There is no shame in using an active method when you can't figure out the passive one.

Cheers,
Bill

P.S. Happy Holidays to you as well, Jon! I hope you and yours had a festive, relaxing, and safe holiday season. How's school going?


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## nealh (Oct 4, 2003)

Thanks BillP

I have come to realize that I am not able to discern the fine differences many audiophiles can..I have very good hearing so I do pick up some of the alternator noise my wife never hears...

At this point I dont care how they get rid of it as long as it is gone..the white noise is inaudible once the car is running..very low volume thing...

Unfortunately I was oncall last weekend and could not bring the car in..so I am trying this weekend but my luck the "service engine soon" light activated and they will look at the car on fri and I hope nothing major so Sat it can go in..get my sub and get rid of the whine

One thing I have noticed regarding the E39(before and after new front speakers) vs my old Audi A4 and my wife's ML 320 with Bose...is the sound is better centered in these cars vs my E39....I guess they did not image it well...sound seems to be more localized to the steering wheel not center of dash or between front seats...

I will ask if they can adjust this but I am sure it will require more labor and money....

I would have thought before placing the doors they would have started setup and make sure it imaged more centered....


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## degglest (Sep 15, 2004)

*Almost same setup!*



jun said:


> I also have the jl amps 500/1 and 300/4. IThe fronts are diamond Audio HEX series and the rears are Diamond Audio coax. I have 2 jl audio 10w6v2 subs. I have the alternator whine right after the install as well as white noise. the installer was saying that he would have to get me a PAC 2 interface for me. The installer is a very well known installer in the area. I came to know him when I saw one of his cars in the magazines.


Hi BillP, Tweeter is about to install almost them same setup in my 330i. The only difference is they are putting in 2 pairs of MB Quart PCE213 5.25" (2-way Component / Coaxial System with 1" tweeter) instead of Diamond Audio coax. How do you like your setup? Was it worth the money?


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## jun (Oct 10, 2002)

From what I heard, MB Quartz sound a little harsh. I don't have any first hand experience on them, just what some people were posting. I used to have a/d/s speakers and subs in my 330ci. I love both these speakers, my former a/d/s and my current diamond audio.


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## nealh (Oct 4, 2003)

jun said:


> From what I heard, MB Quartz sound a little harsh. I don't have any first hand experience on them, just what some people were posting. I used to have a/d/s speakers and subs in my 330ci. I love both these speakers, my former a/d/s and my current diamond audio.


I know some say the MB quarts are harsh..I have the premium line and think they sound great...but you have to listen with your own ears


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## Frank Rizzo (Aug 2, 2003)

*Hey neal......*

I was messin' with the stereo stuff last week and tried something different that you may want to try.
I switched the JL inputs to the "low" setting and turned the gains all the way down to about 1/4 - maybe a little less. Every bit of whine is gone now and it really rocks!!!!!!!!!!!!!!!!!!
I think setting the gains to "high" was a mistake from the get go.I also installed 6db attenuators on the RCA's - so your results may vary.....but I'm really happy with the set up now.


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## nealh (Oct 4, 2003)

Frank Rizzo said:


> I was messin' with the stereo stuff last week and tried something different that you may want to try.
> I switched the JL inputs to the "low" setting and turned the gains all the way down to about 1/4 - maybe a little less. Every bit of whine is gone now and it really rocks!!!!!!!!!!!!!!!!!!
> I think setting the gains to "high" was a mistake from the get go.I also installed 6db attenuators on the RCA's - so your results may vary.....but I'm really happy with the set up now.


Interesting..I think when I set it to Low I had in my case to really turn the gains down..maybe less than yours...I will give it another try...

I have placed a PAC audio converter(can not recall the name) on my RCA that got rid of 90-95% of the whine....

Do you think the Low setting gives a cleaner sound?


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## Frank Rizzo (Aug 2, 2003)

nealh said:


> Interesting..I think when I set it to Low I had in my case to really turn the gains down..maybe less than yours...I will give it another try...
> 
> I have placed a PAC audio converter(can not recall the name) on my RCA that got rid of 90-95% of the whine....
> 
> Do you think the Low setting gives a cleaner sound?


I dont know about cleaner sound, but it let me turn the gains waaaaaaay down, and that all but eliminated the whine!
Let me know.....


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## nealh (Oct 4, 2003)

Frank Rizzo said:


> I dont know about cleaner sound, but it let me turn the gains waaaaaaay down, and that all but eliminated the whine!
> Let me know.....


I will give it a go this weekend..by the way with the gain way down do you feel you as good SQ with low volumes?


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## Frank Rizzo (Aug 2, 2003)

nealh said:


> I will give it a go this weekend..by the way with the gain way down do you feel you as good SQ with low volumes?


The same or better SQ. Email if you want more info or pics. BTW: I never eliminated the "amp always on" dilemma- but this helps reduce the annoyance - also - NO noise on AM either!

.


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## nealh (Oct 4, 2003)

Frank Rizzo said:


> The same or better SQ. Email if you want more info or pics. BTW: I never eliminated the "amp always on" dilemma- but this helps reduce the annoyance - also - NO noise on AM either!
> 
> .


amp on noise..white noise seems to be an issue with how BMW setup the system....I will have time this weekend to tinker...btw what type of attenuator do have on the RCAs...name, brand?

thanks


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## photo2000a (Mar 9, 2004)

*conv tbls*



nealh said:


> amp on noise..white noise seems to be an issue with how BMW setup the system....I will have time this weekend to tinker...btw what type of attenuator do have on the RCAs...name, brand?
> 
> thanks


it sounds like the original poster has troubles going from the original bmw ballanced differential signal to those jbl amps which arent' (theyare line lvl)

I'd recomend either optimally getting a amp which can accept a bal diff signal or a converter to feed your existing jbl such as a VEN4 or equiv

naturally that should help alot, however if the problem of say alt whine persists then the other advice above on that should do the trick

Just a guess as i don't know too much about this stuff

but hope it helps


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## Frank Rizzo (Aug 2, 2003)

nealh said:


> amp on noise..white noise seems to be an issue with how BMW setup the system....I will have time this weekend to tinker...btw what type of attenuator do have on the RCAs...name, brand?
> 
> thanks


No problem. I remember your disapointment with the original set up....

I first used these attenuators (el cheapos) in the -6db varitiey:
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=266-234

Then when I was satisfied that they performed as advertised, I upgraded to the harrison model (still -6db):
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=266-242

They knock down the factory HU signal enough so that the nifty "i'm overdriving the input stage of my JL amp into distortion" sound is gone. I think they are a mandatory buy - if you have not installed a LOC like a VEN-4.

The harrison attenuator is pretty long (I dont remember how your amp is mounted) so I had to gang together a pair of RCA 90 degree connectors to keep them from sticking out past the edge of my amp (I broke one pair off). Now they are on top of the amp an out of the way.


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## nealh (Oct 4, 2003)

what I used was a PAC SNI-1 RCA noise filter..this brought the alternator whine to almost nil....only get the white noise if the amp is high...I am happy with sound(actually very happy)...but I get occasional crackling...

I may have to buy these -6db attenuators..though I guess you need 4...2 for front and rear..are the more expensive ones worth it...

BTW..the audio is very good now and Sirius is great...I went to a JL audio 10in Infinite Baffle sub in my rear deck...I had custom work down and the bass is very good..I may still get a 2nd sub but not sure if I need it


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## Frank Rizzo (Aug 2, 2003)

nealh said:


> what I used was a PAC SNI-1 RCA noise filter..this brought the alternator whine to almost nil....only get the white noise if the amp is high...I am happy with sound(actually very happy)...but I get occasional crackling...
> 
> I may have to buy these -6db attenuators..though I guess you need 4...2 for front and rear..are the more expensive ones worth it...
> 
> BTW..the audio is very good now and Sirius is great...I went to a JL audio 10in Infinite Baffle sub in my rear deck...I had custom work down and the bass is very good..I may still get a 2nd sub but not sure if I need it


The cheapos are priced each, while the more expensive ones are per pair. They both do the same thing...I did not notice a difference (honestly).
Glad to hear it's better!


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## Technic (Jun 24, 2002)

nealh said:


> I got around to upgrading my audio..I had the install done by a very high end installer...
> 
> Front speakers are MB quart PCE 213 5.25 component speakers..premium line
> JL audio 500/5
> ...


Get the Peripheral SuperVendetta 4 (4 channel) , or the SuperVendetta 2 (2 channel) converters and your noise problem should go away. :thumbup:


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## nealh (Oct 4, 2003)

Technic said:


> Get the Peripheral SuperVendetta 4 (4 channel) , or the SuperVendetta 2 (2 channel) converters and your noise problem should go away. :thumbup:


technic..thanks...I assume these are placed behind the HU...How are they installed...I would require a pro to do it

just for those coming late..I used a high end installer in Tampa...who spent 8 hrs plus trying to ID the alternator whine and said there was no way to remove it..the amp was orginially under the rear deck..then it was moved to add a JL audio 10in Infinite baffle sub to the rear deck and interestingly the alternator whine was reduced with the new amp position

They claimed to have tried a ground loop isolator which made the sound worse with no chnage in the whine,Hi/Lo converter, moving the crossovers etc was no help as well..they said major rewiring of items in trunk would be necessary..I do not recall there exact words

anyway I changed JL 500/5(which accepts differential inputs so no Hi/Lo is needed) settings and improved the sound and whine...the white noise can be lessened but never removed..seems to be common with the way BMW designed how the HU is turned on in the 5 series....

I purchased PAC audio SNI-1 filter which reduced noises a fair amount

I am not handy with stuff..I can plug something in it but if wiring/HU removal is necessary I need to use a installer


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## Technic (Jun 24, 2002)

nealh said:


> technic..thanks...I assume these are placed behind the HU...How are they installed...I would require a pro to do it
> 
> just for those coming late..I used a high end installer in Tampa...who spent 8 hrs plus trying to ID the alternator whine and said there was no way to remove it..the amp was orginially under the rear deck..then it was moved to add a JL audio 10in Infinite baffle sub to the rear deck and interestingly the alternator whine was reduced with the new amp position
> 
> ...


These differential/balanced to line converters are installed between the HU and your amp, as simple as getting the HU output leads and connecting them to the converter inputs (8 speaker wires if you get the SVEN4, 4 wires if you get the SVEN2). At the converter output side you will have RCA, line level amplifier inputs.

I am not sure if the inputs of the JL amp are 100% differential/balanced speaker input compatible, because their feature is actually called Differential-Balanced Input _Topology_, which I understand as in "similar formation". Like the amp will take regular line level inputs and internally will process them as D/B inputs, not as in taking native D/B as inputs straight. At least that is what I suspect, I tried to get a complete description of this "Topology" but I could not find anything related... :dunno:

IMO, this can be the reason that you have this noise and the ground loop isolator can do nothing about it. You have to first get those D/B inputs converted and then injected into the amp as line level. By doing this you are performing a double noise suppression: one by taking the HU D/B outputs and converting them to line level, thus effectively canceling most of the noise level just before the amp and then feeding this relatively clean signal to your amp that further process it to a much lower noise level... if any is left from the first stage.

It should work... :thumbup:


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## nealh (Oct 4, 2003)

Thanks Technic

How do I know whether to get a SVEN 4 or 2..does this depend on whether I am using 2 vs 4 channels on the amp 

I may consider this...but will need to see how much installation will cost..I am sorry I did not have a hi/lo converter with the initial work....


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## Kaz (Dec 21, 2001)

Interesting...

Looking at installs over on Fanatics over the years, I was under the impression that the JLs can operate in true balanced mode (sa well as Xtants and newer a/d/s).

I did notice some interesting things when I had my first install in there:

-Bus noise. Every time a bus signal showed up at the rear harness (control signals to the changer or steering wheel stereo controls are used), there would be a faint click in the audio. It was worse with an ancient a/d/s than a newer Blaupunkt.

- noise/distortion from fader position. When the fader is set to full forward or full back, there was all matter of noise and distortion. One click back from the ends, though, and it would all go away.

I will say that with the VEN4 (the old one) and either amp, I had absolutely ZERO alternator whine. In fact, I have more now since I put the SE BT kit in then I ever did with that system.

Hopefully, I'll have ny next system fully in (using the VEN4 again but this time with a 8ch a/d/s running biamped fronts, etc.) after I build the funky sub box and we'll see what comes out from that.


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## Technic (Jun 24, 2002)

nealh said:


> Thanks Technic
> 
> *How do I know whether to get a SVEN 4 or 2..does this depend on whether I am using 2 vs 4 channels on the amp *
> 
> I may consider this...but will need to see how much installation will cost..I am sorry I did not have a hi/lo converter with the initial work....


Exactly... if you are using the 4 channels from your HU you should get the SVEN4, for 2 channel convertion is the SVEN2. :thumbup:


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## Frank Rizzo (Aug 2, 2003)

I like the thoery on the D/B inputs....I never thought of that.

I yanked the VEN4 and went with straight inputs to the JL after I realized that a lot of the noise was being introdouced by other sources than the line in signal. As a matter of fact, I can disconnect the RCA's from the amp and still get noise. Neal can attest that you can have stereo noise while the car if OFF (!!) thanks to the funky BMW turn-on lead almost always supplying +9v. 
I learned too late that you inherit a lot of "issues" when you keep the factory HU, like super high output voltages..... But I did gain steering wheel controls, Sirius, Ipod (waste) and a clean look by keeping the factory stuff.
My best advice is to do what you can to get the gains as low as possible and the noise goes away for the most part.


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## Technic (Jun 24, 2002)

Frank Rizzo said:


> I like the thoery on the D/B inputs....I never thought of that.
> 
> I yanked the VEN4 and went with straight inputs to the JL after I realized that a lot of the noise was being introdouced by other sources than the line in signal. As a matter of fact, I can disconnect the RCA's from the amp and still get noise. Neal can attest that you can have stereo noise while the car if OFF (!!) thanks to the funky BMW turn-on lead almost always supplying +9v.
> I learned too late that you inherit a lot of "issues" when you keep the factory HU, like super high output voltages..... But I did gain steering wheel controls, Sirius, Ipod (waste) and a clean look by keeping the factory stuff.
> My best advice is to do what you can to get the gains as low as possible and the noise goes away for the most part.


Rizzo... some JL amps have the Auto Turn On feature that does not require a separate turn-on lead. The amp turn on is activated by sensing the audio input voltage, so there is a way of reducing the noise even further if it is another source of it.

About the gain issues of the HU, the manual of the JL 250/1 for example have a very good procedure of adjusting the gain of the amplifier using a CD and an AC multimeter.

Good luck... :thumbup:


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## nealh (Oct 4, 2003)

On my 500/5 there is no auto turn on feature...the JL audio manuals IMHO suck....

I am trying to decide if it is worth spending more $$ to get a SVEN 4 installed...just not sure...

Frank, I tried switching the input to "low" setting but in my case the whine alternator whine on my talk radio was too annoying and white noise was much higher..this was with gains all the way down..I do agree seems to sound better

you guys as usually are a wealth of info..thank you very much


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## Frank Rizzo (Aug 2, 2003)

Neal: Try the attenuators FIRST. Dont switch to low unless you drop the signal first. (they are in the mail)

Technic....the JL procedure for setting the gains on the amp won't really work on a stock BMW HU. Show me where the "3/4 volume" level is on the stock HU rotary knob.......and we'll all be able to use the procedure...


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## listener (Feb 9, 2004)

I didn't read the entire thread so forgive me if repeat anything that's been said. I'm in the process of upgrading the stock system (HK) right now and am changing everything BUT the head unit. I grabbed the inputs to the stock amp (radio speaker outputs) in the trunk, and ran them directly into a Fosgate OEQ-2 EQ. This EQ has true balanced inputs in addition to standard RCA inputs. I adjusted the EQ input gain with a test CD to match the source unit output without using any external attenuation. I maxed the output gain on the OEQ-2, which theoretically is 9 volts with a 0 dB (all bits high, max level on a CD, etc.) signal, and adjusted the amp gains accordingly.

It has ZERO noise of any kind. None when adjusting via steering wheel controls, no hiss, no whine. It sounds terrific. I'm actually quite impressed with the stock deck, except for what Rizzo mentioned about the lack of any reference to the volume position on the rotary knob. The OEQ-2 has clipping lights on it, so maybe I'll re-locate those up front somewhere for when I have my "beer ears" on.

If at all possible I would avoid reducing the signal at the dash and running a low voltage signal back. It just leaves you open to more noise issues. Better to leave it "hot" and drop it down if neccessary in the back of the car.

Now the bad news. Fosgate doesn't make the OEQ-2 any more. However, I believe Audio Control makes several signal processors capable of handling a balanced/high-level signal. Besides a little signal processing/EQ never hurt anybody! www.audiocontrol.com


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## Technic (Jun 24, 2002)

Frank Rizzo said:


> Neal: Try the attenuators FIRST. Dont switch to low unless you drop the signal first. (they are in the mail)
> 
> *Technic....the JL procedure for setting the gains on the amp won't really work on a stock BMW HU. Show me where the "3/4 volume" level is on the stock HU rotary knob.......and we'll all be able to use the procedure...*


Although it seems that the knob keeps going and going infinitely, there is a _saturation point_ or volume limit... using the same AC multimeter and a test CD turn the HU volume all the way up and record the max AC level that you see at its output leads. This max AC level should be the Full Volume (saturation point) of the HU. 75% of that max is your target for the procedure.

This should be your first step before performing the JL Audio Input Sensitivity Level Setting. :thumbup:


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## nealh (Oct 4, 2003)

Listerner:


listen very carefully when the car is off and ignition is switch is in position 1...do you get a snowy sound..I thought I did not have it till..I made sure the care was off and I closed the door and listen at the AC vent speaker....with the JL audio amp when I increased the amp gain or set to Low input ...this noise can be amplified and audible...very annoying because it never goes away and can be heard over music with the "right" amp gains


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## dagoo98 (Apr 23, 2004)

listener said:


> I didn't read the entire thread so forgive me if repeat anything that's been said. I'm in the process of upgrading the stock system (HK) right now and am changing everything BUT the head unit. I grabbed the inputs to the stock amp (radio speaker outputs) in the trunk, and ran them directly into a Fosgate OEQ-2 EQ. This EQ has true balanced inputs in addition to standard RCA inputs. I adjusted the EQ input gain with a test CD to match the source unit output without using any external attenuation. I maxed the output gain on the OEQ-2, which theoretically is 9 volts with a 0 dB (all bits high, max level on a CD, etc.) signal, and adjusted the amp gains accordingly.
> 
> It has ZERO noise of any kind. None when adjusting via steering wheel controls, no hiss, no whine. It sounds terrific. I'm actually quite impressed with the stock deck, except for what Rizzo mentioned about the lack of any reference to the volume position on the rotary knob. The OEQ-2 has clipping lights on it, so maybe I'll re-locate those up front somewhere for when I have my "beer ears" on.
> 
> ...


I also installed my JL10W7 to my stock DSP head unit the same way except I used a high/low for the radio speaker outputs. Although it would probably be harder to hear the alternator wine through the sub I nevertheless have no alternator whine and the sub sounds great. I have a fosgate 500.2 amp pushing the sub and the two work well together. I also have a clarion crossover filtering out the frequency and sending low frequencies to the sub. The addition of the crossover did wonders.

Listener, do you think it would be better to take out the high/low and run the radio speaker output wires directly to the crossover?


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## listener (Feb 9, 2004)

nealh said:


> Listerner:
> 
> listen very carefully when the car is off and ignition is switch is in position 1...do you get a snowy sound..I thought I did not have it till..I made sure the care was off and I closed the door and listen at the AC vent speaker....with the JL audio amp when I increased the amp gain or set to Low input ...this noise can be amplified and audible...very annoying because it never goes away and can be heard over music with the "right" amp gains


With my ear very close to the tweeter I can hear a slight hiss. It's the noise floor of the amp as it's there with the amp input disconnected. It's no big deal and to be expected with an amp as large as the one I'm using (4 channels, each capable of about 600 watts RMS). It does not increase with volume. One of the reasons to have a "hot" signal to the amp is so you can keep the amp gain down. However, using more devices to increase that signal can put you right back where you started. I took signal right out of the stock deck directly into an EQ without high to low adaptors. EQ gain and amp gain are set relatively low, and that's what I attribute the lack of noise to.

Over the years amplifier manufacturers have struggled with gain issues. What I mean is you want an amp that has a lot of gain so it "goes loud" on a demo board in the retailers store, but you want to keep the noise low too. Those two don't necessarily go hand in hand. More gain means more noise, period.

My humble opinion is to scrap all that high to low adaptor / noise filter / attenuator stuff, and buy a cool processor that will accept the balanced output of the factory deck.

Also I should have clarified, I have ZERO noise when sitting in the drivers seat in the driving position. Oh and I have MB Quart too (QSD 213's). Love 'em! :thumbup:


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## listener (Feb 9, 2004)

dagoo98 said:


> I also installed my JL10W7 to my stock DSP head unit the same way except I used a high/low for the radio speaker outputs. Although it would probably be harder to hear the alternator wine through the sub I nevertheless have no alternator whine and the sub sounds great. I have a fosgate 500.2 amp pushing the sub and the two work well together. I also have a clarion crossover filtering out the frequency and sending low frequencies to the sub. The addition of the crossover did wonders.
> 
> Listener, do you think it would be better to take out the high/low and run the radio speaker output wires directly to the crossover?


A couple things. First, that amp (nice choice by the way) has a built in crossover, so unless the Clarion piece gives you some additional flexibility and/or functionality, I'm not sure you need it.

Secondly, if you're keeping the crossover and it has high level inputs, you may be able to use them. HOWEVER, it's very common for those type of high level inputs to be common grounded meaning the L- & R- speaker inputs are actually connected together. If so, that's not compatible with the stock deck, although you may be able to use the + inputs only (be careful). Also, if the crossover has high level in it's most likely just a resistor network. This can actually be better for sound quality than the outboard devices using coupling transformers, but can leave you more susceptible to noise.

Do some critical listening, change it around and listen some more. Or you might just say...it ain't broke, so I ain't fixin' it! What ever you do, good luck!


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## nealh (Oct 4, 2003)

Thanks Listener..I am very happy with my sound..I think the MB premiums I have are excellent and IMHO they are not too bright

Unfortunately the high-end installer could not get rid of the alternator whine...they said they tried when they had after install for like 8hrs...not sure how much time they spent on it....

EQ..hmm..probably more than I want to spend now...but this maybe a great idea


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## Frank Rizzo (Aug 2, 2003)

listener said:


> ........amp gain are set relatively low, and that's what I attribute the lack of noise to.


OK - so now back to my original suggestion - since Neal and I are (were) having the same issues.....-6db attenators on the RCA inputs right before the amp drop the crappy HU signal enough to use the LOW setting on the JL 500/5 and turn the input gains DOWN ("low" in your words) and minimizes the effect of stray noise intering the system....plusne less electonic component in the system & less cost :thumbup: ...


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