Just got my MKII 20GB Amber installed a couple of days ago in my 1998 GMC Jimmy. I got the stereo and an MTX 4-channel amp installed at Circuit City. It played fine (just the ride back home) when they first installed it, but now I only get sound out of the right rear and left front speakers. Also, there is a thump on startup of the empeg. I don't think this is the negative spike bug because the player doesn't lose its song position and it doesn't thump when I turn off the ignition. It's only when I turn it on. I took it back to Circuit City and they said it was the empeg. They checked the RCA's and the amp with testers and say everything is working fine. Well, I went home and plugged my empeg into my stereo output through the RCA's. My stereo has 4 speakers and it plays out of every one of them, so I'm pretty sure it's not the empeg. Anyone know what this could be?? The amp meets the specs and I'm running monster cable throughout. Could it be just bad grounding? I trust the "pros" at Circuit City know how to ground it correctly.....

When you checked the 4 channels at home, was this through the sled? All I can think of is that the audio connections in the sled have pulled out, losing a couple of your channels - but you'd be very unlucky to suffer from that on *2* channels and only after the drive home!

The thump on startup doesn't sound right; does the amp have a power light? The amp should only power on when the empeg screen comes on. If it's wired incorrectly, then it may be on all the time and you would get a power on thump.

Hugo

Follow up to this. Luckily, someone else has an emepg at work, and we plugged his into my car and got the same result: power thump at start up and only playing through 2 speakers. It's gotta be the sled, but I won't know for sure until I pull the thing out. (it's a pain) As far as the thump, there is a power light on the amp, and it does not turn on until the empeg is turned on, so it's not that. Any other suggestions??

Start narrowing down the location of the fault. Work the problem.

The first thing to do is to rule out the amp, since you can do it without tearing the dash apart. Get another line-level device, for instance a portable CD player, and plug it into the amp's RCA inputs and listen. Do the front, then plug into rear and listen again.

After that, it's time to dismantle the dash. First thing is to rule out RCA cable problems- use your portable with the cable ends at the front of the car. If it's there, then it's time to start checking the wire runs between the dash and the trunk for problems.

Then start looking at the sled and checking for wiring problems there. See if any of the wires have come undone. Also check the docking connector to make sure there's no trouble (like a bit of fuzz or something screwing up the connector pins). Double-check that the power leads were properly connected, soldered, and shrink-wrapped. Make sure the right power lead was connected to the right inputs (the ignition wire and constant-feed wires are going to the right places).

Just use your common sense: Zero in on the fault by testing at each possible failure point.

___________
Tony Fabris

Update on this. Thanks Tony. I trouble-shooted the "only playing out of 2 speakers" problem by using a portable CD player. I found the player played out of all 4 fine straight into the amp, but only out of two up by the dash. So, it was the RCA's from the amp to the dash. Circuit City says they were pinched by the back seats. They gave me new RCA's and I get sound out of all 4 speakers now!!! It sounds great, except I still have the power thump and I now have the dreaded alternator whine. I thought it was the sled, but they have grounded that really well. Just wondering if I should get one of those Alternator Noise Suppressors or Amplifier Muting Circuits from Crutchfield. Anyone have luck with these??

Update on this. Thanks Tony. I trouble-shooted the "only playing out of 2 speakers" problem by using a portable CD player. I found the player played out of all 4 fine straight into the amp, but only out of two up by the dash. So, it was the RCA's from the amp to the dash. Circuit City says they were pinched by the back seats. They gave me new RCA's and I get sound out of all 4 speakers now!!! It sounds great, except I still have the power thump and I now have the dreaded alternator whine. I thought it was the sled, but they have grounded that really well. Just wondering if I should get one of those Alternator Noise Suppressors or Amplifier Muting Circuits from Crutchfield. Anyone have luck with these??


You didn't mention anything about Alternator Noise on your first post. Was it there then, or did it become apparent after they replaced JUST the RCA's?

Part of this is my natural distrust for Circuit City, as well as the (generallized statement) 'average' install techniques I've seen from their shops. I'd really be suspicious of their wiring here. If they routed your RCA's in a place where they could get crunched.... I'd certainly have all of those wires checked and verify you have a good common ground.

Check this FAQ entry for more info on the alternator whine.

You didn't mention anything about Alternator Noise on your first post. Was it there then, or did it become apparent after they replaced JUST the RCA's?

Ah, I believe this was my fault when I was troubleshooting the RCA's. After pulling out the sled and messing with it, the whine started to happen. This is what leads me to believe that the sled is the culprit, but they put a screw in it and grounded it. I may go with those noise suppressors from Crutchfield...

Greetings!

I have the RCA Line filters, and that really reduces the whine considerably. I purchased, but have not yet installed, the alternator noise suppressor. I am curious to find out how well it works, but I am actually dangerous when messing with wires (which is why I am in computers - lower voltages!!!). Let me know how it works out.

Paul G.
SN# 090000587 (40GB Green)

Eh? With 240+ V AC inside computers, you are worried about 20 V (unregulated) AC in an alternator?

One of the few remaining Mk1 owners... #00015

Not as much the amount of power as opposed to my utter lack of mechanical ability!!! In anything computer related, I can just hot swap a power supply - no cutting of wires, etc. I have freed to much magic smoke in the past not to be a little careful (OK, paranoid).

Paul G.
SN# 090000587 (40GB Green)

Just thought I would share my experiences on this:

Pre empeg, I had a Kenwood 10xCD changer and head unit in the car with a nasty EQ Booster for the front, rear driven from the head unit with a sub from a decent Caliber AMP.

When I put the empeg in I got a terrible whine from the front containing both alternator and digital noise (from the empeg). I thought it was the EQ booster so I replaced it with another AMP. The noise was still there. I was, at this point, thinking the empeg was faulty as I had checked all my cabling.

To cut a long story short I took the AMP back and upgraded it for a different make, problem gone COMPLETELY.

YOu may find that ground loop isolators will help with the noise but I would look closely at the AMP you have in the back.


MK2 Red S/n 949

I fixed it!! I went to Shitty-O Rack (Radio Shack) and bought 2 of those noise suppressors. I put those on my RCA's and made sure to move them farther away from my power cables. I was amazed that it worked. No alternator whine and, more importantly, NO POWER THUMP. And Circuit Shitty said it wouldn't work. Jeez

Rhino
MKII 20GB Amber

Greetings!

Excellent! That was the RCA filters, right? Keep in mind, they probably just cut the level of the noise, it is probably still there. I had a similar experience in the summer when the filters were put in. It seemed much better, but you can still hear it when it is quiet, or if there is a larger electrical load on the car (i.e., rear window defogger, heater, etc.).

Still, I am glad the performance has improved for you!!!

Paul G.
SN# 090000587 (40GB Green)

What was the part number and cost of those noise supressors?

And how far did you move the audio cables from the power cables?

___________
Tony Fabris

Can you post details of what you bought/what you installed? I am sure Tony is just itching to add the details to the FAQ on installations...

One of the few remaining Mk1 owners... #00015

I am sure Tony is just itching to add the details to the FAQ on installations...

Actually, I'm interested for my own sake. I did not take my own advice, and I wired the RCA cables along right next to all the power wires and all the other car wiring. (If you knew how tough it was to get things wired down just ONE side of this car, you'd understand.) There's a little alternator noise (not much-just the tiniest bit) in the system, and I was wondering whether I could get rid of the last of it without having to completely rip up my floor and seriously injure myself again. When the tuners come out, I'll be installing one, and that would be a good time to add extra parts if I thought they'd do some good.

___________
Tony Fabris

Here's what I bought. They were $15 bucks a piece (You need 1 for rear and 1 for front). As far as moving the cables, it wasn't by much. Probably about 6" (I know it is recommended to move them 18").


Rhino
MKII 20GB Amber

As I recall Tony you have a recent accord as do I. In my install there is absolutely no alternator whine or noticable hiss whatsoever. I ran my power down the drivers floor trim, and the RCAs, amp remote, and speaker connects down the center console. They are basically right on top of each other once they get to the back seat as they go to the amps. The old "power and gnd separation" is a myth as all of the amplifier currents travel through the car chassis back to the batt/alt anyways. I would suggest you have some issue with your install if you're having a noise problem.

#080000512 green 12GB

Did you install this device at the amplifier or at the head?

___________
Tony Fabris

My problem is that I ran everything down the driver's side tunnel, which is where everything else is. I didn't do anything through the center console.

The hard part was getting stuff around the B pillar, and along behind the back seat over the rear wheel well. Did you have any trouble in that area? Mine is a 4-door 2000 Accord. Was yours a 4-door?

Like I said, the alternator whine is very faint. I agree that there's probably some sort of ground loop issue, too, since I'm running multiple amplifiers. I'll see if the ground loop isolators get rid of the problem first(30 bucks versus the hassle of ripping up my floor again is a no-brainer), then re-route my audio cables later if that doesn't solve the problem.

The old "power and gnd separation" is a myth as all of the amplifier currents travel through the car chassis back to the batt/alt anyways.

I've never heard of needing to separate power and ground. I've only heard of needing to separate audio cables and power wires.

___________
Tony Fabris

I'm glad Rhino's problem is improved, but I'm very dubious about RCA filters. If his music contains a thump, will he be able to hear it now? The only "filter" that I'd recommend is a common mode choke, but they have will not help much on low frequencies and have to be made very carefully to avoid loss at high frequencies and intermodulation distortion on loud signals.

Below is a repost of a thump related message I sent in the "Feedback>>Bug Reports>>Low battery interrupt" thread. It's a good thread to check out (especially Hugo's posts). Sure enough, he soon found that the constant voltage line was not connected.

If the remote line is working correctly, the amp should be off when the constant line is powered up. Hope this helps.



---begin repost---

A correct car installation shouldn't thump your speakers. I can rip and jam my empeg in and out of my Carrera with wild abandon. A friend
of mine has a thumping installation (more like a gunshot!). After swapping empegs and finding his car thumped with either, we took an
empeg to the lab bench with a spare docking sled I happened to have laying around. We hooked up the RCAs to an amplifier which did not
shut down in response to the empeg's remote line and found that as long as the yellow "Permanent power input" line was hot, you could
flicker the orange "Ignition sense input" recklessly without a thump. If you connect the AC adapter or fiddle with the yellow wire, it thumps
mightily. Interestingly, the yellow input is not necessary to run the empeg, but if you don't use it, you will get a thump when you light up the
orange line. Hope this helps. Also check out Hugo's earlier posts on thresholds. Very interesting!

---end repost---

-jim <MkII:080000260 18G blue>

And regarding the thump, may I also remind everyone about this FAQ entry.

___________
Tony Fabris

Did you install this device at the amplifier or at the head?
This was installed at the head.

I'm glad Rhino's problem is improved, but I'm very dubious about RCA filters. If his music contains a thump, will he be able to hear it now?
I've had no music troubles, although the stuff I listen to isn't really that "thumpy" to begin with. I don't want to give the impression that this is the ultimate solution to your noise troubles. This is not an exact science, and every car is different. It just worked for me. It was a shot in the dark, and because of this, I made sure that I could return the noise filters to Radio Shack if they didn't work for me. I'd say it's worth a try if other things have not worked.


Rhino
MKII 20GB Amber

The noise filters don't affect the music, they do not "filter thumps". That's not what the original question is about. A power-up or power-down thump has nothing to do with the music, it's a timing problem with switching the amplifier on.

___________
Tony Fabris

I thought this device was a ground loop isolator, not a filter? An isolator shouldn't affect the frequency response at all.

Rob

"The old "power and gnd separation" is a myth"
That should have been power and signal, I was getting ahead of myself.

Mine is a 2 door and I'm not sure about the back seat differences, but there was oodles of room. I went under the back seat and along where the wheel well meets the trunk floor with everything.

I would suggest pulling the empeg out and running it off the wall wart and then run a different set of RCAs to the amps. That way you can determine if it's a ground problem with the amps, which is likely the cause.

I would consider any audible whine or hiss to be a problem in $2000+ stereo.

#080000512 green 12GB

It's isolator, not filter. Sorry for the mix-up.

Rhino
MKII 20GB Amber

Myth or not, simply moving the power from the same side with my RCA's to the other side of the car reduced engine noise in my install greatly. The rest was elliminated by turning the gain down on the amps.

Something happened when the power cable was reran down the other side.

Thanks dropping a link to the product info. Two clicks away from that are the specs quoted below. It looks like a flux coupled transformer and the frequency range is predictably horrid. They way they specify the ripple, you just know that it's 6dB down from the center at the band edges (and falling fast!). You may as well sell your sub-woofer if you use this. At the high end, 4kHz is not too sweet either. If this is the weak link of an otherwise superior stereo system, I'd focus on cleaning up the DC power into the empeg and making sure that all the power lines (constant, switched, and remote) are hooked up correctly. A friend's initial installation had the constant line disconnected and the remote line *powering* a big, bad amp. Amazingly it worked, although it thumped and cut out as the volume inched up. By the way, thanks to the empeg guys for designing in a self-resetting breaker on the remote line!

Disclaimer:
My background is mostly RF and DSP, although I have worked some >100dB spurious-free data converters back in the 80's (and you think hard drives used to be expensive). Those converters were 5-50kHz and ground loops were always leaking in around -80dBFS. I tried twin-axial and tri-axial interconnects, flux coupled xformers and chokes. Every time I tried to apply hard earned lessons to my next design, I'd find how little I really knew. Jump on in, you audio gurus, back me up or cut me down!


Ground LP Isolator (270-0054) Specifications Faxback Doc. # 9542

ELECTRICAL DATA:

Impedance Ratio:
Z1:Z2................................................1000 Ohms:600 Ohms
Z1:Z2................................................1000 Ohms:600 Ohms
Frequency Response:.............................300 Hz to 4000 Hz +/- 3 dB
DC Resistance:...............................................@25 degrees C
Z1:....................................................200 Ohms +/- 20%
Z2:....................................................150 Ohms +/- 20%
Insulation:.........................500 VDC apply to primary and secondary
more then 100 Meg Ohms Min.

(ALL-01/26/95)



-jim <MkII:080000260 18G blue>