Need help diagnosing 93 SC300 rear speaker noise issue (bad amp or sub?)
05-06-15, 02:41 AM
#1
Need help diagnosing 93 SC300 rear speaker noise issue (bad amp or sub?)
Hello all,
I've been trying many different search combinations but I'm really not finding anything specific. I suspect what I have is a failing subwoofer or more likely a failing rear factory amp.
SOLVED: This was identified to be a bad factory Pioneer Subwoofer amplifier located under the rear speaker deck.
Post #2 and Post #17 (on page 2) contain the two downloadable sound files that reference the issue.
Background info: My 1993 SC300 has a completely factory Pioneer sound system. CD changer... changes CDs... but basically doesn't work (gives the "CD Err" prompt). And my factory head unit's cassette player has a permanent tape jam. But the AM/FM modes both work and I have set it up for an aux-in jack though the factory test port inside the head unit. I have that wired into an iSimple Tranzit Blu-HF bluetooth audio system. I'm quite happy with it other than my issue.
Now that aux-in connection has a ground loop isolator on it already plus a second body ground I affixed to the side of the head unit. I am NOT getting any alternator noise.
What I am getting is a constant high-pitched noise from the rear speakers. Either the center sub, left, right or all three. But it's only from the back speakers. This buzzing comes and goes by decreasing or increasing in pitch until it occasionally dies out (when at low pitch). And then it will return and build in pitch again until it goes to a very high frequency and just stays there.
Turning the volume **** doesn't increase or decrease this noise. Only going down to zero volume or turning off the head unit stops it. Turn on the headunit or just turn the volume **** up again and the high pitched rear speaker noise is still there at the same constant volume and frequency.
There IS a momentary respite with the head unit on if I press a button to switch modes between AM, FM, TAPE or CD. For a brief second there is no sound whatsoever from the system just before the newly selected sound mode kicks in... which still has the constant high pitched frequency noise from the rear speakers.
This sound also does not vary AT ALL with engine rpm. It's a very constant high-pitched frequency from the back speaker(s).
Other than the aux-in jack with the ground loop isolator and second head unit ground wire, I've got a totally stock factory Pioneer stereo. My speakers are otherwise in good shape with no crackling or signs of impending death.
Can anyone suggest what the issue might be? Bad factory ground somewhere in the back of the car? Bad sub? Bad amp? Something else?
I'd appreciate any suggestions. It has become annoying to the point that I have had to stop using my stereo altogether until I can resolve the issue.
Thanks guys.
-----
Transcript of the first post from my other thread on this topic "Aftermarket amplifier but keeping factory head unit?" which has now been merged with this one:
I know this is probably not something most people do but I like my car's original boring factory Pioneer head unit and I'd like to keep it working.
I am in need of a new amplifier. The stock one apparently has bad capacitors which is the cause of the buzzing noise I mentioned in this thread:
(Thread Link Removed since this is the thread referenced)
A new one, if Lexus even carries it any longer, is around $700+. Obviously that's ridiculous, so I'm probably going to find a used one that's still working and just swap it in. On a chance, I also contacted Tanin Auto about a repair but they confirmed to me that they don't work on these.
But this got me concerned about yet another failure down the road and I wanted to ask if anyone has had luck integrating any new model aftermarket amplifier into their otherwise stock factory Lexus stereo system.
Thanks, all!
I've been trying many different search combinations but I'm really not finding anything specific. I suspect what I have is a failing subwoofer or more likely a failing rear factory amp.
SOLVED: This was identified to be a bad factory Pioneer Subwoofer amplifier located under the rear speaker deck.
Post #2 and Post #17 (on page 2) contain the two downloadable sound files that reference the issue.
Background info: My 1993 SC300 has a completely factory Pioneer sound system. CD changer... changes CDs... but basically doesn't work (gives the "CD Err" prompt). And my factory head unit's cassette player has a permanent tape jam. But the AM/FM modes both work and I have set it up for an aux-in jack though the factory test port inside the head unit. I have that wired into an iSimple Tranzit Blu-HF bluetooth audio system. I'm quite happy with it other than my issue.
Now that aux-in connection has a ground loop isolator on it already plus a second body ground I affixed to the side of the head unit. I am NOT getting any alternator noise.
What I am getting is a constant high-pitched noise from the rear speakers. Either the center sub, left, right or all three. But it's only from the back speakers. This buzzing comes and goes by decreasing or increasing in pitch until it occasionally dies out (when at low pitch). And then it will return and build in pitch again until it goes to a very high frequency and just stays there.
Turning the volume **** doesn't increase or decrease this noise. Only going down to zero volume or turning off the head unit stops it. Turn on the headunit or just turn the volume **** up again and the high pitched rear speaker noise is still there at the same constant volume and frequency.
There IS a momentary respite with the head unit on if I press a button to switch modes between AM, FM, TAPE or CD. For a brief second there is no sound whatsoever from the system just before the newly selected sound mode kicks in... which still has the constant high pitched frequency noise from the rear speakers.
This sound also does not vary AT ALL with engine rpm. It's a very constant high-pitched frequency from the back speaker(s).
Other than the aux-in jack with the ground loop isolator and second head unit ground wire, I've got a totally stock factory Pioneer stereo. My speakers are otherwise in good shape with no crackling or signs of impending death.
Can anyone suggest what the issue might be? Bad factory ground somewhere in the back of the car? Bad sub? Bad amp? Something else?
I'd appreciate any suggestions. It has become annoying to the point that I have had to stop using my stereo altogether until I can resolve the issue.
Thanks guys.
-----
Transcript of the first post from my other thread on this topic "Aftermarket amplifier but keeping factory head unit?" which has now been merged with this one:
I know this is probably not something most people do but I like my car's original boring factory Pioneer head unit and I'd like to keep it working.
I am in need of a new amplifier. The stock one apparently has bad capacitors which is the cause of the buzzing noise I mentioned in this thread:
(Thread Link Removed since this is the thread referenced)
A new one, if Lexus even carries it any longer, is around $700+. Obviously that's ridiculous, so I'm probably going to find a used one that's still working and just swap it in. On a chance, I also contacted Tanin Auto about a repair but they confirmed to me that they don't work on these.
But this got me concerned about yet another failure down the road and I wanted to ask if anyone has had luck integrating any new model aftermarket amplifier into their otherwise stock factory Lexus stereo system.
Thanks, all!
Last edited by KahnBB6; 11-16-15 at 07:09 PM. Reason: Added clarifying detail
05-31-15, 02:02 AM
#2
Update:
This strange aberration suddenly came from my rear center speaker (I think) and definitely NOT the front speakers after turning the car on. I was unable to hit record fast enough to capture the first half of this noise.
As you'll be able to tell from the sound file, it's a lot of erratic squealing like interference which abruptly stops just before the end of the recording. The actual aberration lasted at least 50-45 seconds. This is just the last 30.
Any ideas, guys?
This strange aberration suddenly came from my rear center speaker (I think) and definitely NOT the front speakers after turning the car on. I was unable to hit record fast enough to capture the first half of this noise.
As you'll be able to tell from the sound file, it's a lot of erratic squealing like interference which abruptly stops just before the end of the recording. The actual aberration lasted at least 50-45 seconds. This is just the last 30.
Any ideas, guys?
05-31-15, 09:45 AM
#4
^^ It's definitely not actual radio interference. Download the attached sound file I posted and see what you think. The constant issue is the high pitched noise described in post #1 which doesn't change with engine rpm or volume adjustment.
I think the two issues are related although they are isolated events. Some part of the factory system is beginning to malfunction but at this point it's still very much a useable stereo.
I think the two issues are related although they are isolated events. Some part of the factory system is beginning to malfunction but at this point it's still very much a useable stereo.
05-31-15, 09:52 AM
#5
It's probably a failing capacitor or resistor in the amp power, something that's worth more trouble to diagnose than to spend 2 hours installing a new head unit. I don't know for certain.
Literally, you can spend $150-$200 on a new head unit, get some wires, cut out the factory amp (that has a shared ground if I remember) and I cannot emphasize this enough - DRASTICALLY improve the sound even with the stock speakers.
Literally, you can spend $150-$200 on a new head unit, get some wires, cut out the factory amp (that has a shared ground if I remember) and I cannot emphasize this enough - DRASTICALLY improve the sound even with the stock speakers.
05-31-15, 01:13 PM
#6
I still say radio interference... The only time I've heard noises like that has to do with radio tuning. It doesn't seem coincidental that it's happening at the rear speakers, when the amp for the front speakers is also back there.
05-31-15, 01:28 PM
#7
Yes, but also depends on the year as well IIRC, some had a separate sub amp. Not to mention the Nakamichi models. 
My point was that by going aftermarket, he'd just run new wires and bypass everything, not tap into the existing amp, but......I think the OEM sub still gets powered by part of that amp system, so maybe my idea is out the window, and a better suggestion would be to find a used OEM amp and swap them out to see if it goes away. That's probably the cheapest easier option.
My point was that by going aftermarket, he'd just run new wires and bypass everything, not tap into the existing amp, but......I think the OEM sub still gets powered by part of that amp system, so maybe my idea is out the window, and a better suggestion would be to find a used OEM amp and swap them out to see if it goes away. That's probably the cheapest easier option.
Last edited by ISFFUN; 05-31-15 at 01:32 PM.
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06-01-15, 09:10 AM
#8
t2d2 -- That's worth a try. I don't think it's the radio antenna causing the issues but I can definitely check all the connections back there to be certain. The sounds aren't anything like normal radio interference noises though.
ISFFUN -- The factory amp should be separate on my car which has a stock Pioneer stereo with the trunk CD changer option. I've considered getting a new head unit but a lot of aftermarket single-din and double-din (screen) units don't impress me visually or with their interfaces or with how they blend to the factory dash lines and controls. I've been very happy with the stock function once I wired in an aux jack and bluetooth. I might buy an older Nakamichi CD500 or MB-VI single-din head unit to have on hand just in case the stock one burns out though.
I'm also inclined to guess that it might be the factory amp having issues with capacitors. I think hitting up Aliga or ebay for a used working replacement is probably a good option for me.
ISFFUN -- The factory amp should be separate on my car which has a stock Pioneer stereo with the trunk CD changer option. I've considered getting a new head unit but a lot of aftermarket single-din and double-din (screen) units don't impress me visually or with their interfaces or with how they blend to the factory dash lines and controls. I've been very happy with the stock function once I wired in an aux jack and bluetooth. I might buy an older Nakamichi CD500 or MB-VI single-din head unit to have on hand just in case the stock one burns out though.
I'm also inclined to guess that it might be the factory amp having issues with capacitors. I think hitting up Aliga or ebay for a used working replacement is probably a good option for me.
11-13-15, 03:13 PM
#9
Aftermarket amplifier but keeping factory head unit?
I know this is probably not something most people do but I like my car's original boring factory Pioneer head unit and I'd like to keep it working.
I am in need of a new amplifier. The stock one apparently has bad capacitors which is the cause of the buzzing noise I mentioned in this thread:
https://www.clublexus.com/forums/per...mp-or-sub.html
A new one, if Lexus even carries it any longer, is around $700+. Obviously that's ridiculous, so I'm probably going to find a used one that's still working and just swap it in. On a chance, I also contacted Tanin Auto about a repair but they confirmed to me that they don't work on these.
But this got me concerned about yet another failure down the road and I wanted to ask if anyone has had luck integrating any new model aftermarket amplifier into their otherwise stock factory Lexus stereo system.
Thanks, all!
I am in need of a new amplifier. The stock one apparently has bad capacitors which is the cause of the buzzing noise I mentioned in this thread:
https://www.clublexus.com/forums/per...mp-or-sub.html
A new one, if Lexus even carries it any longer, is around $700+. Obviously that's ridiculous, so I'm probably going to find a used one that's still working and just swap it in. On a chance, I also contacted Tanin Auto about a repair but they confirmed to me that they don't work on these.
But this got me concerned about yet another failure down the road and I wanted to ask if anyone has had luck integrating any new model aftermarket amplifier into their otherwise stock factory Lexus stereo system.
Thanks, all!
11-13-15, 07:44 PM
#10
This recent thread has been enlightening. Began regarding factory Nakamichi cars but veered into the Pioneer cars.
https://www.clublexus.com/forums/sc-...arket-amp.html
I'm beginning to think it's useless to try to do anything but replace the amp with another used one.
Further, I had not realized that the Pioneer cars have an additional separate amp for their peculiar subwoofers.
https://www.clublexus.com/forums/sc-...arket-amp.html
I'm beginning to think it's useless to try to do anything but replace the amp with another used one.
Further, I had not realized that the Pioneer cars have an additional separate amp for their peculiar subwoofers.
11-13-15, 10:20 PM
#11
Yea these audio systems can be tricky as I experienced when I was installing my carPC a few years back. If I remember correctly some SC's (I think the Nakamici ones) use a 5 channel amp that power the sub, while the Pioneer ones use a separate amp to power the sub.
Although any audio shop should be able to integrate a new amp with the factory system, its much easier and cost effective to simply install a whole new audio system while you're at it. For a few hundred more you can have all new speakers, with proper wiring, and a new headunit to go along with your new amp (depending on the cost of your speakers/headunit).
Although any audio shop should be able to integrate a new amp with the factory system, its much easier and cost effective to simply install a whole new audio system while you're at it. For a few hundred more you can have all new speakers, with proper wiring, and a new headunit to go along with your new amp (depending on the cost of your speakers/headunit).
11-13-15, 11:47 PM
#12
^^ Thank you. I know it's a risk to repair the factory system with a used amp that might have similar capacitor wear. For now it actually does still produce beautiful sound. It's just got this intermittent 1600Hz(ish) frequency that is independent of engine rpm or vehicle location. It doesn't always show up but when it does it's hard to tune out. Otherwise the factory stereo still works perfectly. I'm going to try one more test and then pull apart the trunk lining to get to the amps.
You're right. It would be more cost effective over the long term to just replace the whole stereo system but I actually don't need all new speakers. The rear deck units were replaced a couple of years ago and I've been meaning to order the correct size door speakers to have on standby as well. Polk Audio 4" units. Nothing fancy.
My real issue is that I really like the style and simplicity of the factory stereo. Once I did the aux-jack DIY and added a hard-wired Bluetooth audio device it did exactly what I wanted and remained very easy to use.
When I search for replacement head units, 99% of them are just gaudy-weird looking things with too many features, too many buttons or just a full double-din screen with full computer menus that are more complicated than I prefer. In my car I really want mostly solid-state rather than software. Not to mention I feel like most of them not only don't blend with the interior design but call unwanted attention to themselves.
The only aftermarket decks that really appeal to me are the discontinued Nakamichi CD400, CD500 and MB-VI 1-DIN units. Those at least look traditional and logical like the factory Lexus head unit. And those are getting harder to find now. Pyle and Deck make their own ultra-traditional head units but their reliability and sound quality don't even seem up to OEM standard.
I've already put some aftermarket SC stereo conversion parts aside for a rainy day but I've been trying to avoid that.
scENFORCER, you're saying it's still possible to put a simple aftermarket amp in place of the factory unit, all else being stock? I would have to put in a replacement subwoofer as well, correct?
You're right. It would be more cost effective over the long term to just replace the whole stereo system but I actually don't need all new speakers. The rear deck units were replaced a couple of years ago and I've been meaning to order the correct size door speakers to have on standby as well. Polk Audio 4" units. Nothing fancy.
My real issue is that I really like the style and simplicity of the factory stereo. Once I did the aux-jack DIY and added a hard-wired Bluetooth audio device it did exactly what I wanted and remained very easy to use.
When I search for replacement head units, 99% of them are just gaudy-weird looking things with too many features, too many buttons or just a full double-din screen with full computer menus that are more complicated than I prefer. In my car I really want mostly solid-state rather than software. Not to mention I feel like most of them not only don't blend with the interior design but call unwanted attention to themselves.
The only aftermarket decks that really appeal to me are the discontinued Nakamichi CD400, CD500 and MB-VI 1-DIN units. Those at least look traditional and logical like the factory Lexus head unit. And those are getting harder to find now. Pyle and Deck make their own ultra-traditional head units but their reliability and sound quality don't even seem up to OEM standard.
I've already put some aftermarket SC stereo conversion parts aside for a rainy day but I've been trying to avoid that.
scENFORCER, you're saying it's still possible to put a simple aftermarket amp in place of the factory unit, all else being stock? I would have to put in a replacement subwoofer as well, correct?
Last edited by KahnBB6; 11-13-15 at 11:51 PM.
11-13-15, 11:49 PM
#13
Another direction I've gone in the past is to find a factory head unit from another vehicle that you like, and wire it up as desired with new amps and speakers. That retains the factory look and feel, and is less appealing to thieves. Our 2.5 DIN slots can easy take an in-dash Ford / Visteon 6-CD changer, for example, and work with most any external amp. Well, height is no problem. I haven't checked width.
11-14-15, 12:02 AM
#14
t2d2, that's another good idea, as long as there isn't a factory immobilizer issue on the donor head unit.
I just looked up the Ford/Visteon unit and it does look very simple. If I absolutely have to ditch my factory HU I'd consider that one in the list if it's got a good track record and can be repaired if needed.
Width is probably okay. Height of course is generous. Depth as well in the consoles of these cars.
For the moment I really want to keep the stock HU. I've always been very happy with it in both form and function. I still use AM on road trips with the factory antenna, for example. The tape deck function and trunk changer have both been broken since I got the car but the aux-in hack with bluetooth just makes it perfect... to me anyway
I just looked up the Ford/Visteon unit and it does look very simple. If I absolutely have to ditch my factory HU I'd consider that one in the list if it's got a good track record and can be repaired if needed.
Width is probably okay. Height of course is generous. Depth as well in the consoles of these cars.
For the moment I really want to keep the stock HU. I've always been very happy with it in both form and function. I still use AM on road trips with the factory antenna, for example. The tape deck function and trunk changer have both been broken since I got the car but the aux-in hack with bluetooth just makes it perfect... to me anyway
11-14-15, 12:12 AM
#15
I had a remote iPod stereo for a while and was finally able to go back to the Visteon unit after removing the boost gauge. It was a most welcome re-addition.