Help needed diagnosing audio issue

Hi guys & gals. I've got some troubles and desperately need help.

Before I get started, I have to give an enormous shout out to James at Tech12. Even though I've never bought from him, James took time out of his day to help me out and even called the next day with some feedback. Who does this? I can't express my appreciation enough. When it's time to buy new gear, his number will be at the top of my list.

What do I have?

2018 Limited double cab with OEM head unit (has navigation, does not have JBL)
FRAC harness-doubt this has anything to do with it
LC6I
Adapters to OEM plugs so no splicing required
Rockford Fosgate R400-4D
Kenwood components up front and coax out back
Rockford Fosgate R1200-1D
JL Audio Stealthbox
Everything was installed by me.

What's my problem?

RF, RR and LR speakers drop 95% of sound intermittently. Additionally, the LF gets a bit louder and sounds amazing when this happens. When the system is working 'correctly', it sounds great. Sometimes, it sounds like everything fades just a bit as if it isn't getting full power. The volume doesn't just get a bit lower, but the sound is flatter for loss of a better word. The big frustration for me is the 3 dropped channels and that's what is happens most.

I can't duplicate the problem. I've plugged, unplugged, replugged, tugged, pulled, twisted, adjusted, tapped, cursed, driven over speed bumps, driven on bumpy roads, turned the stereo off and on, turned the vehicle off and on and any other kind of thing I can think of. NOTHING that I've done to induce the problem has worked. Additionally, nothing that I've done above has solved the problem, either. I'm one step shy of waving a dead chicken over my head while dancing naked around the vehicle during the next full moon in hopes of fixing this.

Per James, I changed the output channel to see if the music from the RF channel followed. Embarrassingly, I can't remember if it did. I think it did. What I definitely remember is that the RCA connections acted as if they were loose/not getting a good signal. So, I figured the amp was toast and went shopping.

However, I noticed that when the 3 channels drop and I'm using the headunit navigation, the voice is shockingly loud. The music might be at 3 but the voice sounds like it's at 25. This has happened a number of times. So, I'm wondering if it's the head unit, not the amp.

Not only can't I afford to go buy a new amp and a new head unit, I just can't bring myself to start throwing random parts at a problem and hope something works. That's just wrong. And since the problem is intermittent, I can't expect a shop to be able to give a correct diagnosis since nobody knows when this will happen or when.

I'm going to pull the head unit and double check everything behind it just for fun. I did install the FRAC harness last year. Maybe something came undone or rubbed through a wire sheath or something. I have no idea, I just have to do something. I can't take this anymore.

HELP! How do I diagnose this? I'll buy you beer, sparkling water or whatever you drink and be eternally grateful for your help.

Thanks so much.

 

Are you using Channel summing on your LC6i? There are green lights that tell you when signals are being summed. The summing is controlled by DIP switches. I would toggle those switches a couple times just to make sure they are seated into the proper position. Make sure you note what the switch positions are before you start and do the toggling with the power off.

I would also check that any bare wire connections you have such as maybe the inputs to your LC6 are seated well and there are no frayed strands potentially contacting the Chassis or ground terminals.

 

I'll suggest putting everything back to stock and see if there is still a problem. If so, you should still have some warranty.

 

It sounds like the system is switching modes and which signal goes where somehow on its own?
Does this happen with all sources?
Is there any soundfield or surround decoding going on anywhere in any of the components in the system?
I am not familiar with most of the stuff you are using but is there any Digital transmission going on either from a source to the Head Unit r from the Head Unit to Amps and is there a Crossover or processor in the chain somewhere too?

I would start bypassing anything in the signal chain one by one and see if you can isolate the issue after seeing if it happens with all sources or if maybe only with Sat or Radio for instance?

And please I think I speak for everyone here,no pics of that dance thing you hint at!?

So after reading the manual for the Output Converter for a minute I have a feeling that somehow that is the culprit as it is the only thing there that actually modifies the signal chain at all.

It is important that you "Remember" the answer to the question that James asked as this holds the secret I bet to whether there is a bad set or bad connection or bad converter.
This is also why I asked about the different sources and whether it happens with all sources or just one.
We need to know if when swapped the strange behavior follows the swap!

That Converter Summing feature is what I think is going berserk somehow but it also can only sum what input it receives too so it can also be the Head Unit output which is why I want to know about the sources.

 

Ok, channels 2 and 3 were NOT summed. They are now. No stray wires anywhere. Its still going loud LF and almost nothing on the other 3. No joy.

I'm getting a lot of hiss now. This is new as of last night. If I press buttons on the side of the head unit (home, apps and audio) the hiss is very briefly interrupted while it changes screens.

Unfortunately, I can't revert to stock as I tossed the oem amp 2weekends ago. I was going to keep it just for fun, but in a massive garage overhaul and clean out, it got tossed.

It happens on all sources. Again, being intermittent, I have no idea how a shop can diagnose it until something fails 100%.

Playing with the output RCA and the loud LF is not following wherever Iplug it in. This rules something out, right? Even when the LF is playing full and loud, the signal isn't right. I can hear the woofer distorting. So, I keep the volume at 2 or 3 just to hear something. Do I have the head unit blues?

I'd dig the better sound quality and features of an aftermarket head unit but love the stealthy nature of my system. My truck has been broken into once already and they completely missed the amps and sub. Lousy bad guy I suppose.

I'm off to the market to buy that chicken.

 

Audio Volume is really just AC voltage. So one way to diagnose signal level issues is to Isolate your audio components and measure AC RMS voltages along your audio path. Turn the amp and LC6 gains all the way down before starting this so you’re not trying to amplify an open input during testing.

To do so you’ll need a constant level signal of pink noise source playing through the HU. You can use your phone as a Bluetooth source to the HU. You can find pink noise recordings on YouTube that should work fine.

Verify that the pink noise is playing through your HU then disconnect the inputs to the LC6 so you have isolated the HU and measure and write down the voltage on each channel pair as you increase Head Unit volume. I like to use 0, 16, 32, 48, and 63 volume values to take measurements across the volume range. If the balance and fade controls are centered, you should have about the same voltage in each channel at each level as you adjust the HU volume knob. This will tell you if the HU signals are good. Then reconnect HU to LC6 and check the LC6 output voltages to the amp in the same way. “Un-Sum” the channels and set the channel gains equally starting at min and then about 25% increments for each channel.

This might help to isolate the problematic component and save a chicken.

 

OK so you are losing me now?

What exactly do you mean by were not summed but are now?
When and why did you change this?

Also if you had an amp in stock system why use the Level Converter in new system,Level from Head should already be able to drive an amp right?
Did you use the Level Converter just for the use of the connectors?
Are the Head Unit outputs Speaker Level or Signal Level(RCA)?

When you say playing with the output RCA what are you actually talking about? Which RCAs?????

Do you have any small amplified speaker of any kind like a bluetooth speaker with a low level audio input too that you can connect to the amp in signals and see what they sound like?

This is all like trying to fix anything without being there because it is exactly that and you will be well served just having a tech take a look in person so you can try to quantify what is really going on.
One thing for sure though is that you need to stop doing more than one thing at a time and try each step alone or you will never understand the problem!

 

TundraTex, thank you! I never would have been able to figure any of that out. If I can get some time to myself tomorrow, I'll follow your instructions and report back what I get.

ezdog, please don't take this personally, but TundraTex is a mad genius in my opinion. I'm following his lead as best as I can and feeding information to the forum in case anyone sees something that I don't-or if TundraTex is secretly trying to get my head to explode playing with electricity, they can warn me. By the way, I already don't understand. When it comes to electricity, the only thing I know for certain is that it can hurt me. That's why I'm posting to the board. Well, that and I'm a bit untrusting of local stereo shops. I'd rather replace everything myself than have somebody start hacking in to things and securing wires with duct tape and wire nuts.

But to answer your questions...

Keep in mind, I'm somewhat ignorant to a lot of this. I'm not trying to be a dick.

The LC6i is a line out converter. It takes the stock signal and through magic makes it something that the amp can use. Believe me, I don't understand the technicalities here. It is the only way I could get a signal from the OEM headunit to the aftermarket amp. When you say level converter, I'm not sure if we're talking about the same thing.

The stock signal can be summed in the LC6i. My rudimentary understanding is that this means I can draw a full signal from the OEM headunit and divide it as necessary in the LC6i to send to the appropriate channels. Someone please correct me if I'm wrong. I changed it last night. Why? Well, I had assumed it was already summed. When TundraTex asked if I was summing the channels and to toggle switches on and off in case something was funky there, I realized that I hadn't summed the channels. At that point, since the system isn't working correctly anyway, I'll sum them and see if it makes any difference. It didn't.

The stock amp is rather weak. I wanted more power to drive aftermarket speakers and a sub.

I honestly don't know what the head unit outputs are. They certainly aren't RCA. There is a harness sold by a few places that lets you plug everything in using OEM (style) connections so that the harness doesn't have to be cut. If they were speaker out puts, it would seem to me that people would connect straight to their aftermarket amps and not use a line out converter.

By output RCA, I was referring to the output of the 4ch amp. Since the LF speaker seemed to be getting a louder signal than the other 3 when the system acted up, I used that LF output to power the other speakers one at a time. If the sound at the other speakers was identical, then I'd know those 3 channels were dropping for some reason. Plus, James at Tech12 wanted me to do this to help him diagnose the problem.

No, I don't have any speaker like that.

No random stereo shop for me, thanks. The one that gets the best reviews has screwed up a vehicle of mine before. They only want to sell me a new system this time around. They've completely ignored my budget and came up with a $5500 system for me. On top of that, they forgot to include some speakers and sound deadening in that quote. So, they can kick rocks as far as I'm concerned.

Perhaps my post wasn't clear. I tried to determine if the LF signal would work on other channels. It doesn't. Then per TundraTex, I looked into the switches. That's it unless cursing up a blue streak every time the signal drops counts.

 

My first thought was using stock head unit, and harness is your problem.

 

-Edited to remove most of my reply,I am over this now.
It sounds like a wiring issue first really.


I can not speak to the Mad Genius you reference except to say that measuring levels would be a terrific troubleshooting tool here if your problems were not intermittent?

It does not sound like a level mismatch of any kind to me that you will ever be able to control as long as something keeps changing without cause which is the problem you have if I am hearing you right?

So I would look at the connections first for that,the actual wiring and connectors between everything which you started off telling us seemed loose to you too?
There have to be RCA cables between the Audio Control and the Amp,right?
Did you make or buy those cables?
There have to be bare wires going INTO the Audio Control from the Head Unit Harness,Right?
If there is even one tiny strand of wire from any of this touching another connection this is exactly the kind of issue that can cause the intermittent issues you describe.

Anyway I am only trying to help and the problem is it is really tough to quantify what is happening in a Forum like this.
This is why I have suggested only changing one thing at a time so you can really track any changes that you make when reconnecting things.

 

@ForceV4, First of all I appreciate the compliment, but i'm no genius. I'm just an old guy who is too stubborn to give up and I happen to have accidentally learned a few things along the way. I applaud you for taking on this project and asking for help. That's how you learn. You did a great job of describing your installation, components, and problem in a very non-dickish manner. What wasn't clear is if it ever worked properly for a while, or if you had the intermittent problems from the time you installed everything. Anyway, here's a brief run-down of the component functions and some set-up thoughts for your audio chain.

First, the Non-JBL Head Unit puts out 4 channels (FR, FL, RR, RL) of full-spectrum (or full "audio range") speaker level audio. The three dash speakers receive the full-spectrum FR and FL audio directly from the HU and use passive crossovers (filters) to select the proper frequency range of audio for each speaker. The two front side speakers act as high frequency (tweeter) speakers and the center speaker gets passthrough audio from each front side speaker. The same full spectrum FR FL speaker signals from the HU to the dash speakers also go the non-JBL amp. The amp performs active crossover filtering and drives the front door speakers with a mid/low range of the audio frequencies. It also amplifies the power a little more for the door speakers since they can handle greater power than the dash speakers. The RR and RL channels from the HU are also speaker level signals and feed the rear tweeters directly if your truck has them. (Note that most Dual Cabs won't have rear tweeters). And just like the front channels, the rear channels also go to the Amp where they are filtered for mid range, boosted a bit, and output to the rear door speakers. And by the way, the reason you use coaxial speakers in the rear is to give you both mid range and tweeter sound from one speaker assembly. The coaxial speaker has internal passive crossover to filter the lows and mids out of the tweeter signal.

Now on to the LC6i. This unit has a lot of features but to keep from muddying the water, I will focus on the features and setting you should use for your setup. The whole purpose of this Line Output Converter is to reduce the speaker level, full spectrum signals from the head unit into low-noise, filtered pre-amp signals that are compatible with a higher quality aftermarket amp. The Entune HU has 4 channels of output so you should be connecting the front L/R channels to your LC6 Main input and your rear L/R channels to the LC6 channel 2 inputs. "Channel" terminology can be confusing here. Normally a channel is equivalent to a speaker. The LC6 accepts up to 6 channel inputs (thats why it's called an LC6) but they label the inputs as channel 1, 2, and 3 because their channel terminology refers to Stereo (L/R) channel pairs as channels. I won't get in to the summing function in detail, but basically since you have full spectrum audio coming from the head unit, you don't need or want the summing function in the LC6, so you should go back to factory defaults (non-summed) for that. Since the HU signals coming into the LC6 are already amplified speaker levels, you don't want a lot of gain through the LC6. I would turn each output level to about the 11 o'clock position - or lower - as a starting point. If you feed too much signal to the amp from the LC6 you can get distortion or clipping that could cause some of the audio level problems you are having. Without a realtime analyzer (RTA) or a good pink nose setup, it's hard to set these levels properly, so just go with the idea that less is more for the LC6 gain since you already have speaker level signals from the HU. There is a "maximized" LED on the cover. With pink noise or good level music playing on the HU, set the HU volume to 3/4 (48). The maximized light should be barely flickering or completely off with a proper setting. If it is illuminated as a solid light or heavily flickering, you have the gains set too high. Finally, the LC6 will automatically create an additional channel output pair - what they call channel 3 - from the channel 2 inputs. This is controlled by the auto mode jumper that should be in the factory default position of Auto. The channel 3 output can then be used as an input to your 1200-1D for the Sub.

Now the last part of the chain; the Amps. I already mentioned the 1200-1D above. It has internal active crossovers for the sub frequencies (50 - 250 hertz) so it takes the full-range audio input and filters out what the Sub needs. I would set the frequency pass to the full clockwise position (250 Hz). The 400-4D does the same thing for the Mid Range Door speakers. You have a little more control of the active cross-overs here. Each channel has a Crossover mode switch (labelled X-Over). With your configuration I would set these to HP (High-Pass) and then adjust the Frequency potentiometer to about the 2 o'clock position. This will filter out frequencies below about 125 Hz from going to your door speakers and "pass" the rest of the higher frequencies. This is a play it by ear thing based on your preferences on how much Sub Bass you want coming out of your door speakers. I like to have a little bass response out of the doors and leave the lower bass frequencies to the sub. And finally; gain. First adjust your LC6 outputs as discussed above, then set your amplifier gains to minimum. Then adjust your HU volume to same level as above (48). Now adjust the amp channel gains to the desired levels. You shouldn't need to adjust the amp gains beyond about 6 or 7 to get a pretty decent power out. This will be pretty loud since the HU is set to 48, but it should be crisp and clear with no hiss or muted audio. If you have either of these, reduce the Amp gain until it sounds clear and level in all channels.

Please excuse the wordiness, but it helps to understand what everything in your system does to know how to set it up properly. If you're lucky, the volume issues could be due to incorrect gain levels in the LC6 or the Amp. Let us know how it works out.

 

@ezdog your question about summing indicates that you don't understand much about the Toyota audio system design or the functionality of the LC6. You are wrong in assuming no line converter is required. You are obviously unaware that the Toyota non-JBL HU outputs speaker level signals, NOT "non speaker levels" as you stated. This setup is a little unique and definitely requires a line converter to avoid over-driving the aftermarket amp. You also don't appear to know much about the Entune HU since you are not aware that the factory HU has no RCA connecters. All signals are routed through the multi-pin connectors. It's a good thing to try to help someone asking questions, but if you yourself don't understand the basics of the factory set-up or the aftermarket components being used, there is no way on earth for you to understand or diagnose the possible causes of the problem. You are not alone in your incorrect assumptions about the Toyota audio system. It is not a "normal" design. And unless you have studied the factory schematics, it's not apparent how it really works. My post above should help clarify. You are right that it is best to change one thing at a time while troubleshooting to avoid confusion. I'm just trying to provide additional clarity, so to echo your own words above; please don't take this personally, I am observing what you have written and that's all.

Hope this helps.

 

Sh*t. I guess I left the most important part out of my original post. Everything worked great for months. These troubles are all new. I'm out here now trying to get some measurements and will update soon.

 

@ezdog, please don't delete prior posts. There is no telling what might help someone down the road who may stumble upon this thread. I genuinely appreciate the effort.

 

At the risk of showing my ignorance, I'm supposed to check these signals with a multimeter set to AC voltage, no? If so, I'm having trouble as my free Harbor Freight multimeter refuses to function in AC voltage. I can read DC voltage all I like.

Edit OK, I've got a reading in AC voltage on the input of the rear channels only and only if I read across speakers. Meaning, I can read pos or negative of the left with the pos or negative of the right and get a consistent reading. If I read pos to neg of the same channel, I get nothing on all channels. I get nothing on the output of the 4 channels from the LC6i. However, I'm getting a test tone from all 4 channels as tested by my ears. I'm so damn frustrated right now that I can't think straight. It drives me nuts to accept having to take my truck in someplace for a diagnosis. I don't know if I'm screwing up, if the multimeter is broken or if my stereo system is possessed. I'm going to go talk to the dog about life and throw the ball for her.

 

@ForceV4 go through the post I put up this morning. And see if it’s a little easier to check things out that way.
Just out of curiosity, what are your gain dials set to on the LC6 and the amp?

 

I have access to a decent multimeter now and will try this all again.

Gains on everything are roughly 1/3 of maximum. Ill be double checking that, too, now that I have a meter.

 

Well, I think I have some data that can be interpreted. 1 hiccup though. I forgot to undo the head unit wires to the LC6i this time. I just measured with them hooked up. I'm happy to do it over tomorrow if necessary. Oh, the gains were way higher than I thought. I must have dialed in another half turn for some odd reason. That was resolved prior to testing.

I dialed the gain all the way back and set the volume at 48 while playing a sine wave @ 1k hz (I think). Input at LC6i LF 5.09, RF 5.51, LR 7.15 RR 7.75 all measured twice with no significant difference. Output (RCAs disconnected) LF measured .114 the first time, .053 the second time. RF .116 first with jumps to 5.xx and .063 2nd time. LR .063 twice and RR .061 twice.

If I put on my thinking cap and cinch it really tight, I'm thinking the LC6i has given up the ghost. Would that be correct? If so, what do you recommend replacing it with? Another one of the same would make life easy, maybe the 7i version if that does anything fancy for me, otherwise I'm open.

 

Sounds like you’re making headway! I would repeat what you did with a pink noise playing. That way you get a number of frequencies rather than just one. It will give you a better feel for full spectrum performance rather than just 1Khz.

if you continue to have problems with the LC outputs then you could start there. Is it still under warranty?

 

Will do just that tomorrow.

I was so excited thinking the problem had been found. You aren't convinced, though. Hmm. I do the test again and see what happens.

No, the warranty is history.

 

I would agree that it is pointing that direction. Using broadband noise at various levels will help confirm. One thought. I believe Crutchfield and maybe others offer a return policy if you decide you don’t like or want your item within a certain period of time.

 

Today I tested at volume 48 (I just saw your post about various levels, oops) and got the following.
Input FL 1.18, FR 1.18 RL .8 RR .9 and on the output FR .01 and .003, FL .004 and .08, RR .007 and .01 RL .008 and .08.

I used pink noise and white noise with similar results. I'm a bit saddened that this test doesn't have quite the discrepancy that the first one did. Perhaps the stereo is screwing up again this morning.

 

I sent you a PM. Give me a call if you’d like to talk through some additional steps.

 

@TundraTex, thank you for the help. I set the volume back at 48 and attempted to adjust the gains on the LC6i to where I could get .8 to 1 volt across 4 channels and it won't work. In the front, I can get to .9 volts but it isn't constant. It wiggles around a bit. In the rear, I can get to .6. This is with the gains on the LC at maximum. If I set the gains to 1/2 and the volume on 30 of the headunit, I have .3 volts of output for the front. Something is fishy.

Oddly enough, I have nothing hooked up to the 3rd channel on the LC6i. The sub amp get's it's signal from the output of the 4ch amp. So, when I played with the gain on the 3rd channel just for fun, when the sub and the tweeters up front change, I become puzzled. BTW, this 3rd channel was summed. I unsummed it and now it's just the sub level that gets changed. This doesn't make any sense to me as there is NOTHING plugged into the output of the LC6. This is interesting and I am only posting it now because I just discovered it. My main concern is the 4 channels and why they are so darn funky and if this isn't related, I don't much care at the moment. At least it works.

 

Your last sentence is what caught my eye. Is everything working now?

I wouldn’t be too concerned About the .3 volts on the output. It could be the response time of your voltmeter. Audio is AC voltage but it is best viewed on an RTA. A voltmeter is good enough To set equal levels though. The goal is to have them all roughly equal and the gains to roughly equal positions. After that, the final amp can be set to the desired levels and you’re good to go.

 

No joy. It cut 3 channels again inside of 5 minutes of driving on smooth road.

 

Sounds like it’s time for a new LC

 

Yes, it is. If Toyota were to release a 94 to 97 LC with lockers and a big V8 instead of the 6 banger, I would sell my sisters into slavery to buy one. Plus, it would come with a new stereo.

I bought a new LC7i (same thing with bass something or other) and as soon as I plugged it in, it didthe same damn thing. The hissing was better though. Also, after turning the key off, the LC7 stayed on for maybe 5 seconds and I got a pop out of the LF. I tried it again to see if it was a fluke and it happened again.

So its narrowed down to the head unit, an amp, wiring or a poltergeist. To say that I'm frustrated is an understatement. Maybe there are 2 things wrong.

I have an appointment to have it diagnosed at a shop on Tuesday. I desperately don't want to do that. I really, really don't want to do that.

 

Solved! There was 1 wire to the LR speaker that had issues. The amp was at fault for the rest of it. Finally it is resolved. I can't thank @TundraTex enough for all of his help. While we didn't solve the problem, I've learned a few things about electronics and measuring things with a multimeter.

And just for fun, after my last post, the left channel went out in my garage stereo. Ha. Ha. Ha. No irony there. Plus, my windshield cracked like a spider web after washing the Tundra. I must have really pissed the automotive gods off recently.

 

Pretty sure that I told you it looked like a wiring issue to me.