One thing leads to another.. the unending tale of adding an amplifier and speakers to a SSP equipped Boxster - Damn alternator whine!

Ya know how one thing sorta leads to another? Usually it's the "while I'm in the area syndrome" - but in this case - it's strictly one-thing leading to another thing. The trigger for this one thing was having to come up with a Christmas gift idea two years ago. I get bugged for some gift idea usually around the first week in December every year - two Christmases ago - using my usual technique of browsing sites selling Porsche stuff - I spotted something on Suncoast that looked interesting. 987/986 Boxster Rear Speaker Kit Check out the deal on 987/986 Boxster Rear Speaker Kit at Suncoast Porsche Parts & Accessories www.suncoastparts.com It adds 2x 3.5" Coax speakers in each side of the storage binny thing. I posted a longish thread here about installing them: Installation notes on Suncoast's storage-bin... When I installed these speakers I wired them into the rear speaker output wires from my headunit at the time (a decade-old Rosen one).. and I found they added to the system, but it wasn't really dramatic. At the time it seemed good enough since the Rosen was limited in what it could do. The thing with this speaker kit is - the speakers (4 Ohms each) are wired in parallel - making them a 2 Ohm load. That's almost a short circuit - but apparently, most modern amps can handle that load. I should describe the audio system I'm working on - it was a Sound System Plus according to the build sheet, using an ASK amplifier and ASK speakers. It supposedly came from the factory with 7 speakers (2 dash tweeters, one dash center speaker, 4 door speakers - two woofers and two midranges per door.) All the diagrams and drawings for this system show the ASK amp as being mounted low on the firewall in the frunk - behind the fix-a-flat stuff. My car has nothing there... one or two references were seen to an amp located under the passenger's seat - and indeed there is a large module under that seat that I'm assuming is the amp (I don't have the ambition to R&R the seat to make sure, but maybe I could stick my cell phone under and take some photos.) So the Rosen system was sending speaker level signals to the ASK amp - 4 channels signals (which is what the factory harness and connector support.) I assume some sorting of signals takes place in the amp, and from there the signals go out to the speakers. At least that's what the wiring diagrams show for the SSP/ASK system (which probably differs from the 987.1 SSP systems..) Anyway - I had since added the Chinese Android headunit ( Outstanding Tech Contribution! - DIY on installing an... ) - wired the same as the Rosen was. The volume from these added speakers dropped enough that it was hard to tell if they were connected, so the obvious answer is a not very powerful or expensive amp dedicated to just driving these speakers, and rated for use at 2 Ohms. So - that's how one project led to another. Swap the headunit, can't hear the speakers, add an amp. Easy/peasy solution right? Not so much. The initial amp I tried was a "Boss" amp from Amazon. Claimed 100W/channel at 2 Ohms, but no details on if that was actually RMS Watts and what frequency range that rating was at (ie - +/- 1dB, 10-20k Hertz). That didn't matter a bunch. I took time disassembling the inside frunk liner (very few videos online about that - but it's mostly a matter of finding all the T15 screws, removing them, and pulling hard. The frunk light will disconnect itself - no lock on that connector.) I then looked around and found an unused 2" grommet going from the frunk CD-changer compartment into the cowl area. The only problem - it's behind a bracket that holds the evaporative canister/test assembly for fuel vapor recovery - and you have to remove that bracket (2 x T30 - then pry it out from the top, it will pop out eventually). That gave me access to the compartment above the fuel tank where Porsche normally mounted a CD changer if that was part of the vehicle build. Unfortunately - the nearest grommet going into the passenger compartment through the firewall is behind the battery on the port (driver's side). That's OK since moving the battery also makes it easier to get wires through the first grommet into the frunk, so battery disconnected and slid aside so I could get access to that grommet. I then ran two 4 wire cables from the radio compartment to the area in the frunk, and I added a fused lead from the battery and one from what I assumed was ground. The 2 4-wire cables were a signal cable to the amplifier from the headunit rear speaker leads, and a 4-wire cable running the output from the amp back to the wiring for the added-on speakers. I wired this up - put the fuse in the lead and ZAPPP. Hmmm.. I guess I was just too damn tired - I tried it again, ZAPPP. I was running out of fuses at this point.. so I thought the amp was DOA and packed it up and back to Amazon it went. I ordered a different amp - a tiny one from Brazil - and it showed up a day later (gotta love overnight shipping..) I wired that same amp input to the wire and put in a fuse - and ZAPPP. I was definitely getting low on fuses now, so I sat puzzling about what the issue was. The issue was - reversed polarity. I now can understand perfectly how people install the battery backward in these cars. Porsche gives no real clue as to what terminal is the positive terminal. If my brain had been working, I would have realized the wire I disconnected to move the battery was the negative terminal, but by this point I was frazzled. Both connecting cables going to the battery are black. I think this is the only car I've ever seen where the positive cable is black. RED is standard. Red is used for power wiring everywhere else on the Boxster and my Cayenne (red with stripes sometimes.. but red always means power..) My PTouch provided a label clearly labeling the positive terminal. So I swapped the leads at the battery and the whole thing came to life. And it sound pretty damn good, so I started cleaning up the installation and putting tools away, putting the headunit back in the dash, etc. It sounded really good - I could hear the music from the rear speakers, and they'd help a lot when the top is down and the car was moving. THEN - I started the engine to keep the battery up. And "whineeeeeeeee" nicely in tune with the engine RPMs. Alternator noise. Dammit. So I went online and view numerous videos of people chasing alternator noise, with lots of suggestions, some of which they claimed did work, and some that simply didn't. There were various devices suggested (an in-line audio whine filter/ground-loop isolator, and a filter for the input power line - I bought these at a local auto-audio store - they didn't help.) One suggestion was to run RCA cables from the headunit to the amp instead of using speaker-level cabling. So I did that - I pulled the headunit out and hooked up a pair of 6' long RCA cables I had - to the front output jacks (there are no rear RCA output jacks unfortunately) and it sounded pretty good. Even with the engine running, but draped over the top of the windshield from the headunit to the amp. So I took everything apart again and ran the RCA cables through the grommets from the headunit to the amp. Sounded great until I started the engine. The whine was reduced by about 60%, but it was still there and noticeable. So I tried improving the amplifier ground (moved it from the battery terminal to a nearby ground stud on the inner firewall.) That helped a little bit - but I don't think the whine is at the amp now, I suspect it's coming from the output terminals of the headunit. The reason I think that is it goes away if I disconnect the inputs at the amp, and if I turn the headunit volume all the way down - it stops. As soon as I turn the volume control even 5 degrees - it starts up again and remains at a constant volume despite the volume setting, so I suspect it's being introduced in the output stages of the headunit. I'll have to confirm this by also disconnecting the RCA level outputs from the headunit at the headunit. So - tomorrow a bunch of ferrite clip-on lumps arrive from Amazon. I'll try those first on the input power line to the headunit. If they don't solve the problem it will be time for me to try the second of the in-line power filters that I bought from Amazon. the only issue with that is space is REALLY limited in the radio bay so it will be a challenge fitting it in. BTW - a kit of about 60 automotive fuses from Amazon was cheaper than 2 of the little blister packs from AutoZone, and I had them the same day (delivered around midnight..) That's been the past 6 days' project. The wife has stopped asking if it's done yet. And that's one thing leading to another... Digression - the reason I do these sorts of projects is they keep the car fresh for me. My normal history with cars is 3 years and I'm bored to tears with them, and in comes another one. There have been only a few exceptions to this pattern - one was a Volvo 122S wagon I owned for 17 years, continually making little changes to it that I liked (I fall asleep thinking how to do these sorts of things) and the other is the Boxster. I haven't gotten bored with the Boxster and it's nearing 4 years now. My wife is surprised. Happily, I still have some projects I'm thinking about for the Boxster so for now it's a keeper. I suspect a lot of the people here who hang out and tinker with their cars have the same syndrome. Dunno what to call it, I'll have to think about that when I'm falling asleep tonight.

Now you know why I haven't replaced my HU with the one you have!

Subscribed as I have the same speakers in my 986 with aftermarket amp and HU. And the wine exists. Haven’t tried to resolve yet so will be interested in what works for you.

So far - using RCA cables from audio level output on the headunit didn't work. Moving grounds around to try to minimize wiring for grounds and centralize them didn't seem to help. Adding an RF filter on the input power to the amplifier didn't work. Adding ferrite lumps to the RCA audio cables at the amp end did nothing. Adding ferrite lumps on the power feed to the amplifier did nothing. Tomorrow afternoon, the headunit is getting pulled out again (it's been in and out over a dozen times for various changes and modifications and just because..) and I'll try adding ferrite lumps to the power feed to the headunit. If that doesn't help I'll try a local 1mF 100V capacitor from the power into the headunit to ground. If that doesn't help I'll consider how much work it will be to try adding the active RF filter (I bought 2 just 'cause they were really pretty cheap) to the input power line for the headunit. If none of those work - I'm going to try a different amplifier, although in this case - I think I've proven to myself that it's not an amplifier issue. One thing that was in one of the many videos on YouTube on audio induced- alternator whine - that was claimed a 100% success rate - was adding a very large active RF filter feed-though in the output wire from the alternator . This isn't simple or cheap to do probably - unless that lead is run back separately to the positive battery cable. That might make it possible to add that filter (it's a bit large) in the cowl area by the battery , there is a bit of spare room there.. These filters are available for 50A to 150A output alternators. The Boxster uses a 150A output alternator (astounding - I can remember 30A generators on cars.. but I'm old..) The filter is: https://powerwerx.com/newmar-150a-alternator-line-noise-filter - but the one review makes me wonder if it would be worthwhile or not - and make me buy it from somewhere with a no questions asked return policy. Amazon has a listing for it - but no way to order it and no price (very odd..) https://www.amazon.com/Newmar-150-A-Alternator-Filter/dp/B00IO5KSR8/ref=sr_1_1 - ah, found if I click "All buying options" an Amazon vendor offers them for 1/3rd more than the other link I posted above (>$300). Will hopefully have some good news to report tomorrow...

Oh jeez, Don - This sounds like a terrible amount of frustrating and not fun tinkering! Yuck. 987 amp was definitely moved from the frunk ( 987.1 - at least Bose in my former 987.1S) to under the passenger's seat ( 987.2 , SPP). Ask me how I know... Tough call, but you may want to consider just stepping backwards if you can (as that's what I bet you'd tell me) per troubleshooting. I personally find that the original ASK amplifier for SPP (door woofers plus center channel) and my Sony HU are just fine for my purposes. After doing my speaker upgrade in my thread back in March/April, I had enough boom using the ASK amp that my ears literally hurt for a week. Not kidding. Now, I'm now definitely leaving a set of earplugs in the car... My gut says that if you can't isolate the whine, either the Chinese HU or amp (or both) should be pulled from the system to troubleshoot the culprit. This is the first I've heard of any sort of whine with the Chinese HU -- and it's becoming rather popular. So by the process of elimination, it's the amp. Again, there's a lot of detail here -- so I may be missing something. FWIW, I've tried a ton of RF noise suppression over the years (computers, pro-audio for both wireless and XLR cable sound, HiFi) and nothing truly worked a charm from what I remember. I did try some gold foil tape for a wireless signal in my Mac (Bluetooth interference) and for my radar detector (messing with the 981 's HU NAV signal) -- I which I had some limited success. But instead of trying to knock it down, I'd try to eliminate it altogether at the source -- that is if you can. Usually AM is far more susceptible to alternator whine (hence the reason automakers want to discontinue AM radios...as EVs generate a tone of RF interference). Just my two cents, and happy to help troubleshoot if I can! Standing by for your results with the filters et al...

Some snippage of verbosity.. Hows the shoulder? I didn't write up yesterday's adventures because they weren't productive except for proving some things aren't the cause of the issue. I tried multiple capacitors at multiple places and they made no difference at all. I also tried multiple ferrite beads on various wires - again - no difference. Since there is no noise when there are no cables hooked to the amp inputs - it's not noise coming over the power feed to the amp (that was unlikely anyway since the amp power is right from the battery, the wires are about 14" long for ground and positive - and the battery is about as low an impedance as can be imagined - think of it as a giant capacitor... the DC there shouldn't have any ripple on it. Other DC circuits in the car may well have some alternator hash on them, and the current cable routing is causing this to be picked up. I think I noted it before - but several days ago when I first made up the RCA cables to go from the headunit to the CD-changer compartment - I wanted to test that my splices were OK - and I plugged them into the outputs from the dash headunit, tossed them over the windshield, and into the frunk to the amplifier. I started the engine. There was no whine. Everything sounded wonderful. Something is making enough alternator hash that the cables are picking it up (they were rather primitive 40-year-old cables and possibly not as well shielded as might be hoped..) My super-nuclear-grade, dual-shielded, twisted conductor, gold-plated connectors, and silver-plated conductors RCA cables arrived just a bit ago from Amazon - I'm going to be repeating this experiment tomorrow. I fully expect that it will be absolutely quiet. Driving with the cables routed this way is probably not a good idea. Then I'll think about the routing of them. A friend - my mechanic who also is a ham and has a masters in EE and I discussed it at lunch today. The real answer is probably routing and the quality of the cables. If that doesn't work there is another cure. A huge capacitor across the alternator output (right at the alternator) - lets DC pass, but takes any AC component and shorts it out to ground. There is a German company that sells a 0.3 Farad capacitor (3,000 uF) made just for that purpose. About $75. That gets installed across the alternator output to ground. In my big box'o'capacitors (most of which say WECo on them - does anyone know what that stands for?) I have a large blue computer-grade capacitor. About 3" in diameter, 6" tall, 60V. I seem to recall it's somewhere around 5000uF (or 0.5 Farads).. I'll have to reform it (put voltage on it gradually increasing from 0-40V or so) but it should be useable for this purpose. It's the same as the big audio capacitors that shops sell for large $$. Sigh... the project continues. When that's done, I have to install the replacement for the driver's door woofer that's sitting in a box (with 5 other speakers from an ASK system).. and get rid of the buzz in that speaker. One thing leads to another and another and...

Not that it matters, but 3000 uF is not 0.3 F... it's 0.003 F... As a test, have you tried running the radio without the engine running? Does the noise go away when on the battery -only? Also, as you probably know, you can get big-farad caps that are generally used for preventing voltage sag on subwoofers. For example, here's one at BB: https://www.bestbuy.com/site/metra-one-farad-digital-capacitor-silver/1086136.p?skuId=1086136 . I figure you could get one, try it, and then return it if it doesn't help? I have run into noise issues like this with low-cost HUs in the past. That's one reason I have usually leaned towards brand name units (my preferred being Pioneer). That said, your experience with this HU has been good until now, so I am certainly interested to see what you end up finding as a solution. You've tried most of the things I would have. I have heard of cables being routed "near" each other causing problems, but I will say I have never experienced it myself. My old cars had big subwoofers and systems, and even with Radio Shack RCA cables, I never had this issue. The cables weren't fancy either... not super shielded or anything like that. That reminds me, be sure you are not shielding cables at both ends. That's an EE no-no. Shielded cables should ONLY be connected on one end, otherwise you will create a ground loop. Generally you shield at the source-end of the signal (ie the HU)... but sometimes I have shielded on the other side without issue. Also, related story, in one case, I was not able to resolve noise issues without using a ground loop isolator. This is basically a transformer that breaks the connections between the two units. Nothing else I tried worked. Just another device to try and test with.

Sounds perfect without the engine running (possibly lost somewhere in the too-long descriptions above..) It's only an issue with the engine running. I have to look at what's in the box'o'caps in the cellar. I don't see it being a headunit issue.. if you go back to the beginning I had this issue with the speaker-level out connection to the amp - a fairly low impedance output - that also goes to the ASK amp - which isn't having this issue. I think the routing is the critical issue. BTDT already - also described above. The interesting thing is - all these devices have ground wires they say not to connect unless there is no signal through the transformer. That was the case with this setup, so it was necessary to ground the transformer. I have no idea what the circuitry is in it except for the transformer. More fun with it today.. we'll see if re-routing with super-cables helps at all.

Very funny, Don! We both know that I'm not the most succinct...but hopefully I'm getting better at it! LOL. Sorry to hear the noise suppression measures aren't cutting it. I hate to say it, but I'm not surprised per the results now that I think of it. Just had a thought. As RF is RF, last year I had a major issue per RF interference with the backup camera -- which is a super-long RCA run of the car from camera to HU (which I'm guessing would act as an antenna -- especially near the alternator). I did add a capacitor in there intended for backup cameras (quick Amazon purchase) and it did clean up much of the interference -- but not completely. So, I'm guessing that this may be a similar issue -- and it's likely HU agnostic. Our alternators must be throwing a ton of interference, and correcting that at the source would be ideal. Aside from that, better shielding (cables, etc.) might help? Cheering you on here, Don. You got this!

I haven't been exactly succinct either in this thread.. I'm kinda waffling on. Today was about 8 hours of taking the car apart and putting it back together - eliminating another possibility for the whine. I replaced my homemade RCA cables with some double-shielded, magic metal, gold up the wazoo, Amazon cables (made in China - but what isn't). The job required stripping out the frunk plastic again (I'm getting pretty good at it - about 10 minutes now for removal, but 20 or so for reinstallation..) I ran the new cables so they didn't go near any power lines except in the one grommet going into the CD changer compartment - and then they were at 90 degrees to each other - so minimal chances of transmitted alternator noise. Of course this involved more than just running the new cables - the new ones are considerably bigger in insulation size (double-shielded) and stiffer, so some creative routing was required. I also decided to install the ground-loop protection box (an audio transformer) out of sight in the area right below the radio mounting. This made it easy to connect to the radio (leads from the transformer are perfect length to reach the leads on the headunit) and moved it to a spot where it is also shielded by the metal all around it. In doing that - I had to disassemble some wiring that someone else had done for the Sprint Booster - and I managed to clip the SB cable in half while trying to cut off a tie wrap while laying on my stomach on the door sill with my head under the steering wheel. So - this added about 45-60 minutes to the job - repairing the cable. It's a tiny tiny dual conductor cable (size 22 wire x 2) where the only real way to fix it right was to solder it and use shrink wrap to insulate it. I did a staggered splice - where the first wire had a long side and a short side, and the other wire had a short side and a long side. This staggers the joints so even if it wasn't well insulated (it was) they couldn't short. All of this had to be done in 85F 90% humidity with my head under the steering wheel with a soldering station sharing the wheel well with me. As I said - one thing leads to another.. Before I even ran the new wires I did a test - hooking one end of the new wires to the amp in the frunk, draping the wire over the windshield, and hooking it to the head unit. In the past when I did this - and I ran the engine - there was no whine. I also tried this with my homemade cables. BOTH of them exhibited whine. Disconnecting the circuit at any junction eliminates the whine. So I had no real hope this would solve anything, but since I bought the cables and had everything torn apart - I installed the new cables. On reassembly - the whine was the same. What was a bit different was there is now a loud pop through the speakers when the new amp powers up, and a strange whistle noise (sounds like the noise used for bombs dropping from WW-II planes in movies.. wheeeeeeeeeeeeeee - decreasing frequency think Doppler effect..) on power off which makes me suspect of the amp I installed. Another oddity - the head unit didn't turn off when I pulled the key out of the ignition - for at least 30 seconds or more. Very odd behavior. I could hear the aux amp I installed shutting down, but the headunit stayed on. I finally went into the menus and found a setting I remembered - that allows the headunit to stay on ## seconds (your choice of 3-30) after the auxiliary power is turned off. So I set it to 3 seconds, and sure enough - about 3-4 seconds after I pulled the key the radio shut down. I have absolutely no idea why that behavior changed. So - I'm down to the amp. The amp I bought claims to be 100W into 2 Ohms per channel - but it's only about 4" square and 1.25" high. I looked at the rating as rather questionable - but figured if it didn't work out it goes back to Amazon. I think it might be the source of the whine. There's no way there are any decent capacitors inside that small box, and the box isn't getting more than just barely warm - so it's not working very hard. It's going back to Amazon. I've ordered an upgrade brand name amp - from Amazon - arriving between now and 7AM in the morning - a BLAUPUNKT 750W 2-Channel amp. The specs reveal it's actually maybe 100 Watts per channel RMS both channels driven. It's big enough to have some decent size capacitors and chokes in it - so maybe - this will work. If that doesn't work - in studying the ASK amplifier diagram for my car - it shows a connection for "rear speakers, left/right" - a Boxster doesn't have rear speakers unless someone bought the kit I have. My WAG is those channels are sitting there on the amp unused. So if all else fails - I'll rewire the speakers to go to the unused channels on the ASK amp (under the passenger's seat)... probably should have done that to begin with - but "one thing leads to another..."

Wow. Sorry your whoas continue. Hopefully the new amp is the key! Shawn in VA (USA)

Shawn - unfortunately it wasn't. Same noise.. but things have gotten worse. I'm pretty convinced it's internal to the headunit itself, and I think it's a capacitor failing... I did hook up a 30,000mF, 60V computer capacitor across the DC input to the unit - it had no effect at all - so it's not noise in the power line going to the unit. I did lots of other tests with filters and the big capacitor in other spots in the wiring harnesses - and it made no difference. The big capacitor is good (I "re-formed" it before trying to use it - if you're an EE or ham radio guy you'll know what that means) - it holds a nice charge for at least several minutes after the voltage is removed from it (enough charge for a nice ZAP-spark when I short the disconnected terminals with a screwdriver.) What now has been happening is two things: - The unit doesn't turn off as soon as the accessory power is removed from it. The actual power for the unit is unswitched - stays on all the time - a trigger 12V signal from the accessory circuit turns on the circuitry. That's pretty standard practice. It should turn off when the ACC circuit depowers when the key is removed. It's not - for at least 2 minutes now (yesterday it was 1 minute..) There is also a sound coming out of the speakers running off the ASK amp that is getting its input signals from the speaker outputs from the unit - the sound happens when it finally decides to shut off - it sounds like the classic noise used for a falling-bomb in a WW-II movie. ZEEEeEEeeeEEeeeeeeee - decreasing frequency. - And finally - went to dinner with my wife tonight - amp was connected - when I parked the alternator sort of noise was SO annoying I pulled the fuse for the amp (I put that fuse where it's very easy to get to). When we left dinner to drive home - I still had the whining noise - it's now coming out of the speakers that came with the car (ie - powered by the ASK amp - which is fed signals from the output stages of the headunit - just like the PCM3 did.. and CD30). So whatever the noise is - it's now carrying over the other wiring into the ASK amp - and it didn't for sure do this before. My WAG - is a failing capacitor somewhere in the unit. Whatever the cause is - I've asked them for a replacement unit - we'll see what happens with that. Until then I'd suggest that anyone considering one wait to see if this can be resolved. I'll keep the forum up to date on it. Not real happy in NJ...

After sleeping on this overnight - the thought came to me (during restless sleep last night) - that perhaps it's not alternator whine that I'm hearing - that it might be can-bus noise. I seem to recall hearing about this in another thread on an aftermarket headunit in a 981 . I might explore that a bit today - even to the extent of disconnecting the can-bus interface box. See if the whine goes away. I'll report back...

[mention]Cayman Ed [/mention] did you have canbus noise? (Maybe solved by faulty component?) Shawn in VA (USA)

Shawn - I think we need @Cayman Ed to get his attention (at sign, username).. Anyway - I spent today just testing things. I tried a number of scenarios to try to sort out what's happening. I'll describe each one: The basic architecture of the system, no connections made. The headunit output feeds an ASK amp, located under the passenger's seat, using the factory harness (twisted pair wiring, small gauge - around #20 size. The diagram is greatly simplified (if anyone wants a diagram of the wiring for the ASK amp - just ping me) - showing basic components. Left to right: ASK System Speakers - there are actually 7 of them, 3 in the dash (left, center, right) and 2 in each door. The ASK amplifier - has an output dedicated to each speaker and built-in crossovers in the amp that determine what frequency range each speaker receives in the audio spectrum. There are actually 9 channels in the ASK amp - two more for the rear speakers on a Cayman. Those are unused on the Boxster. I suspect those are full-range channels. This is a fairly sophisticated setup... The headunit - has front and rear speaker level outputs (typically several volts) - which are connected to the inputs of the ASK amp. The factory units also fed speaker-level signals to the ASK amp, so all is well with that setup. The headunit also has two RCA level outputs (typically less than 1V) for left and right. I believe these are a mix of the front and rear channels in the headunit. RCA Signal Ground Isolation transformer - A simple 1:1 audio transformer used to isolate grounds and avoid "ground loops" (Google it..) Mounted in the console right below the radio box (behind the HVAC control unit.) This was tested in and out of the circuit a number of times and it made no difference at all. The Added Amp - right now is a Blaupunkt 300W amplifier (overkill, but it was inexpensive and very well built - a hefty piece of gear actually) this amp has RCA level inputs. Another amp I used also had speaker-level inputs - but they were basically the same inputs. I suspect the Blaupunkt amp also could accept a speaker-level input - if not I have a magic box that converts speaker-level signals into RCA-level inputs. Loudspeaker Level Connections: This was the first try, tapping into the rear channel speaker level outputs from the headunit and running twisted pair cabling from the headunit to the amplifier in the frunk. The result was - the buzzing noise - related to engine speed - at the add-on speakers. I tried using a transformer system that converts the speaker level signal to an RCA level signal and also isolates grounds (to avoid ground loops) - with no success. The buzz persisted. It was not changed by changing the volume on the head unit, it was changed by altering the gain on the auxiliary amplifier. RCA Level feeds to the amp: In this case, I ran RCA cables from the RCA left/right outputs on the headunit to the added amplifier mounted in the frunk: The result in this case was interesting - and it changed. At first, when I did this I only heard buzz out of the added speakers. After some time (and R&R of the headunit a half-dozen times) I started hearing buzz out of the original factory speakers AND the added speakers. The buzz is being transmitted in both directions. One end disconnected: A simple test - I disconnected the RCA leads from the headunit. The buzz in the ASK speakers disappeared. The buzz in the added-amp/speakers remained. Other end (added amp) disconnected: Second simple test - I disconnected the plugs from the inputs of the added amp - and the buzz disappeared on the added speakers, but it remained on the ASK system speakers. It seems sort of obvious that some signal is traveling back from the cables through the output RCA plugs on the headunit into the amplifier circuitry. The buzz existed as soon as the volume knob was turned above its zero position, and remained at a constant volume, indicating the outputs are past the volume control circuitry - which makes sense since you'd want an auxiliary amp to be controlled by the main volume control on the headunit. I also out of curiosity tried shorting the cable ends in the frunk, signal to ground - no change at all. I tried making a remote ground to the ground conductor on the cables - no change at all. Final - no connections: Finally - no connections. I disconnected the RCA-level connections from both ends. And not to my surprise - there was no buzzing from any speakers. Conclusion: I suspect something is causing interference on the RCA level cabling and on even the speaker level cabling. The wires run from the headunit, out the left side of the console at the rear, down behind the carpeting to a point where there would be a clutch cylinder/pedal on a 6-speed. Instead of the clutch cylinder - there is a nice grommet in the firewall that seemed ideal for passing wires through. So I used it. The wiring then passes through the battery compartment, and through another grommet in the second firewall - that grommet is located where on a right-hand-drive car - the brake pedal assembly/master cylinder would be mounted. It comes out and travels a very short distance back toward the center of the car to where the amplifier is living (in the CD changer compartment.) I have one more set of cables I'll try - these were from Crutchfield - and a bit expensive - and hopefully well shielded. I tried moving the cabling in the frunk around and it has no effect on the buzz. I'm guessing there are some strong CANBUS signals floating around behind the dash in the area of the instrument cluster... but that's just a guess. And one-thing-leads-to-another: The headunit has gotten into a mode where it does a delayed shutoff after the key is removed from the ignition. I originally thought this shutdown was triggered by the loss of the auxiliary power that comes on with the key in the ignition. But I no longer think this is the case. I was studying the wiring connectors today with the help of some pin-out charts and found that the "trigger" signal connection in the large connector has no wire coming out of it on the radio side of the harness. They aren't using the trigger signal to control the power state of the unit. That to me means it must be using the CANBUS activity to trigger the power on. I can shut it down - at least stop the sound and turn off the display using the power/volume control (pressing it in for about 10 seconds). It appears that puts it into hibernation mode since if I press the control again, it comes back on exactly like it was when I shut it off. No reboot (as happens when the actual shutdown happens.) My AliExpress contact is doing some research on this - he did have me check that the sleep options were turned off (there is an option to [1] leave the system on for a user-settable period of time after key removal and/or [2] put the system in a sleep mode instead of a power off mode. I selected to not use the delayed shutoff and to not use sleep mode. It's been that way since I installed it - and it hasn't changed - just the behavior has. Puzzling. The RCA level isolator: I'm not certain what besides a simple audio transformer is inside this case - but the instructions for it said to only connect the extra wire to ground IF no signal passed through the device. In this case - it was necessary to ground the extra wire for it to work. Donno what's up with that...

BTW - Under One-thing-leads.... The falling bomb noise isn't from the audio system. It's from the engine compartment I think. I replaced the AOS about 12,000 miles ago (3 years) with a genuine Porsche one. It would seem disappointing that it might fail this quickly. I do want to check the gasket on the oil fill cap - it's certainly possible that might be leaking a bit and making that noise. Or - one of the plastic hoses in the engine compartment has failed... just something else to frustrate me.

Unfortunately, I still have that relay switch clicking noise behind the dash or firewall when key fob is inserted after trying the new wire harness from Erisin (through AliExpress ) as they suspect to be a Canbus issue. Clicking goes away when key is in Ignition ON or after car has started so I just have to live with it. I don't have any engine whine noise transmitting to my stereo. Very quiet when ON. Don, can you try other ways to power your stereo HU? For the sake of investigation & elimination, tap the yellow and red lead wires of the stereo to another fuse or even direct to battery and do a quick test on engine whine.

Ed - sounds like your issue is different from mine. I also considered noise coming into the headunit via the power feed - if you track back in this thread you'll see where I tried putting a 33,000mF capacitor across the 12+ input to the unit and ground. It had no effect at all. I also tried the same with the amplifier.. that size capacitor would almost certainly kill any ripple on the DC feeds. I have considered trying to get my old HP oscilloscope working again (only been about 25 years since I last turned it on) and looking for the noise using it.. The fact that both ends are quiet when the cable isn't connected - and then whichever end (or both) is connected has the buzz makes me think it's noise transferred to the cable somehow. Luckily we have company coming for a week+ tomorrow (son, daughter-in-law and granddaughter) means I won't be wasting entire days in the garage trying to solve this..

I heard back from my connection at AliExpress about the shutdown issue: I asked about this - and this was the response I got.... So - interesting. It seems they are using the ACCESSORY circuit to trigger the power-on to the unit. I'll have to track down which lead is the accessory lead going to the headunit. I had assumed it was the "trigger" connection that was used (and it's right next to the +12V constant power and ground connection in the connector. More on this later..

I thought there was no switched +12VAC in the stock ( quadlock ) harness and the trigger came through CANBUS. Maybe that is only with the basic headunit with no other fancy stuff like CD changer or ASK.

There is what's called the "Wake" connection in the Quadlock - I'm guessing it's switched by the ignition. The puzzle is - the harness they made up with the female quadlock socket has no pin for this connection - so that's why I also thought it was controlled by the Canbus. The radio that I removed from the car (the Rosen one) did have an added circuit to a switched fuse in the fusebox - one of those add a circuit fuse thingies. I suspect this was used to trigger the Rosen to turn on. Found my diagram for the ASK system Quadlock : Their Quadlock socket has no wire coming out of pin #16 (Wake) - which I suspect is actually the accessory power. I think I need to converse with them some more. One thing I might try - there are a lot of different options for the CanBus interface - as far as cars it hooks up to and protocols it used. The default one that came on it is for a Cayenne - there is none I could find for a Boxster or Cayman. I might try switching it to a different Porsche protocol and see what happens. Hopefully I can always switch back if something breaks doing this.

From memory I thought that "wake" was an output from the head unit to trigger an external Amp. I don't have my notes handy to verify.

Thanks. Not the first time TaT has tricked me! Shawn in VA (USA)

There is an "Amp On" pin (blue box below) on the smaller set of pins. With their quadlock harness that's the only populated pin of the small pins. I've seen other drawings of very similar connectors where all the large wires are in the same places - and the pin in the box is labeled "ACC". I'll stick a voltmeter on it next time the HU is out.

Don, In case you need this as reference: This diagram came from Erisin during the time we were trying to resolve the relay switch ticking issue. The red arrow points to the Canbus Low that they wanted me to cut before they sent me a new wire quad harness already pre-cut Can Low wire. There is similarity to the diagram you posted on Amp turn ON.

I found an excellent source of installation instructions - and a VERY possible clue as to what is causing the whine in the amplifier circuits.. The source: Install How To Articles for 997 & 987 – Car Audio Innovations - HIGHLY RECOMMEND BOOKMARKING THIS! And the big clue: Duh on me. I might have tie-wrapped the audio cables to this main-charge-cable, or at best in very close proximity to it. So hopefully I can re-route the wires without too major disassembly of the car. I'm opening things up in a day or so - I'm expecting a replacement for the USB cables for the unit, I managed to destroy them with the repeated R&R of the head unit, the vendor warrantied a pair for me for a very nominal charge. And I have a new 46-LTE antenna. The one that came with the unit the cord on it was slightly shorter than optimal, and I think mounting the unit on the inside of the A-pillar passenger's side isn't a great location for it. I think it's going to go on the actual windshield so both sides of the antenna are free from any metal blockage. I'm tempted to try mounting it behind the rear-view mirror.. it wouldn't be very obvious there and that's about as clear an area as I can think of. Amazon has replacements for these antennas with a 10' wire - 2 of them for about $12 (didn't need 2 - so if someone else needs one - get in touch..) Anyway - there will be quite a bit of re-routing going on, so - once I get a bit of time from my company (family visiting) I'll report back here..

YEA!

I have same issue, show me how you put them at 90 or otherwise out of the way

The article above is absolutely correct. I moved the RCA cables from against the firewall (and near the battery wire they show) to cross above the dash under panel. Not a bad place to run them. It leads pretty directly into the radio compartment. I used some little tie-wrap-pads (self-adhesive) on the inside plastic surface of the dash under panel to hold them in place. There is no whine, no noise, just great sound now. YEA! BTW - I also replaced the 4G-LTE antenna - I mounted one behind the rear-view mirror on the inside of the windshield. Sitting in the driver's seat it's barely visible, and ditto on the passenger seat. I ran the cabling behind the interior trim around the windshield then into the dash and across to the radio compartment. For good luck, I tie-wrapped it to the audio cables I'd just run across inside the dash. The antenna works great - I'm seeing a strong 4G signal parked in my garage. On the original, the wire was just a bit short, and wouldn't let me get the unit out of the dash far enough to work on things. I had used some SMA extensions - but apparently, they weren't capable of passing the antenna signal very well since signal strength dropped a lot when I used them (basically making the 4G connection unusable.) That combined with the poor placement for 360-degree antenna coverage on the old one made the new one a real improvement in 4G performance. And I replaced the two USB cables that I'd broken - the new ones are now secured to the unit itself so they shouldn't pull on the connectors (where the old ones broke.) The USB cables let me mount my USB thumb drive again with the 5,000+ or so songs on it. Everything is working nicely, except it still doesn't instantly turn off when I remove the key. It seems to wait until the rest of the car's computers shut down (15 minutes roughly) and then it shuts itself off. The sound quality is now excellent except for some bass-note buzzing on one of the door woofers. It's a torn cone surround. Very common as these age. I'll be replacing that in a day or so (I bought a complete set of take-out speakers from a member here..) Having full-range speakers right behind the headrests I think will make it much more useable when the top is down.

Hi everyone, I noticed a whine from my speakers anytime the car is moving, which stops as soon as the car comes to a complete halt. I researched the topic, reading all the possible causes including amp grounding. to confirm it’s amp-related, I removed the 25 and 10 fuses and the whine stopped completely. Am I right in assuming that this is, in fact, an amp grounding issue? if yes, how can I fix it? I have a 997.1 C4S Cab with the Bose system Thanks Hassan

Hi Hassan, Is the whine on a totally stock system or has anything in the system been changed? If something was changed - depending on what was changed it could be either a grounding issue, OR the changes caused the system to become more sensitive to RF-radiated noise. If something wasn't changed - then I'd consider checking all the factory grounds you can find an perhaps cleaning them and making sure they're secure, then check the connections for the larger wire from the engine to the battery, and finally - consult with an automotive electronics place (they do exist - usually have BOSCH somewhere in their name) about the possibility that your alternator has a bad diode in it (it can still work, just not quite as well and it puts out a lot of RF noise when the diode goes bad.) The interesting symptom you have is the noise stops when you stop. Does it come back if you go into neutral and reve the engine?

Hi Don, it’s all stock at the moment; waiting for my Android system to arrive next week. Where can I find all the factory grounds to clean them, and how do I clean them. If that doesn’t solve it, I’ll take it to get the alternator checked. When the car is stopped, the noise completely disappears but when I’m moving, regardless whether I’m accelerating or not, the whine comes back. When I accelerate, I think it gets louder but the exhaust note drowns everything out. Thanks Hassan

Hassan, When moving does: 1 - The whine stay at a constant frequency? 2 - Or does the frequency change with speed? 3 - Or does the frequency change with engine RPM? And is the whine coming from 4 - ALL the speakers 5 - None of the speakers 6 - Certain of the speakers? 6A - which ones? ​

So, I'm pretty sure it goes up, and I would guess it's speed-dependent (not RPM). It gets pretty loud so I can't hear it when I am accelerating or even moving, but I can hear it at ~25mph and as I slow down, I can hear the frequency reduce until I completely stop. Once I stop, it goes off instantly. I think it largely comes from the rear speakers (I can hear it behind me). I don't think it comes from the engine bay since I couldn't hear any whine when I removed the 10 and 25 fuses. Thanks Hassan

I think you have to really try to answer 1, 2, and 3 before I'd hazard even a guess. Each of them implies something different: 1 - Related to vehicle speed - a constant frequency hum? Something like a fan motor arcing. 2 - Changes with road speed - odd but not unknown for some mechanical part to generate RF interference that's directly related to road speed, meaning it's something from the clutch to the wheels, or involving the front wheels/brakes. 3 - Changes with engine speed - alternator immediately comes to mind. Good luck.