JBL Premium sound system problem

Hi o_intent! The fact that another RAV4 Prime owner reported an identical issue suggests this could be a software bug affecting certain Toyota models.

 

I'm my opinion the weak rear door sound with the JBL is by design. Generally when designing a system you want the majority of the sound coming from the fronts to set a proper sound stage. The rear is just used to fill in a little bit if needed, and provide something for those passengers. The priority is for the driver to have the best sound quality and you don't really need rear speakers to do that. Pulling the sound behind you is a bad thing. (Highs especially)

The fact that they opted to go with no sub at all is more disturbing to me than the rear speaker tuning.

 

I realize this may be a long shot but it would be quite helpful in addressing some of these JBL amplifier issues.

I keep noticing this port on the amplifier.



And thinking it looks a lot like a Micro B USB port.


Than I started searching around to see if I could find any references utilizing this port on the amplifier. I came across this product description for the JBL DSP4086 amplifier which doesn't exactly match the JBL amplifier in the Prius but to me is sounds pretty similar. The point that particularly might be relevant to this topic is mentioning of accessing a tuning interface via PC software available on JBL site to tune the amp channels.


Here is a screenshot of the software running on a PC.



I do not have a portable PC available at the moment to easily check this out. If someone on this thread has a pc available, a mico B usb cable and the JBL audio on their Prius here is a link if they want to see if by chance it works. The software file is available in the Specs and Download section for the amplifier.

https://www.jbl.com/car-amplifiers/DSPAMPLIFIERDSP4086.html

 

That port is not a micro usb it's some kinda proprietary connector.

 

I verified it is not micro usb 5 pin like PhoS said. After do some more reading and searching my next best guess is USB Mini-b (4-pin) aka Kodak U-4 usb.

Here it is on a USB plug from C2G cable.


Here it is on a Kodak printer.



And here is a better shot of the receptacle on the JBL amplifier.



I ordered one from amazon and will see if it fits.

 

It's a stretch but I have a little hope. That would be nuts if the JBL software will communicate. Usually OEM stuff is buried under multiple layers of encryption and proprietary software you could never get your hands on. I would guess the main reason the plug is still there is because they are flashing the AMP with whatever firmware is needed per vehicle. This exact JBL amplifier has been used across many Toyotas for years now.

With everything right there under the driver seat it would be tempting to just replace the factory amp with one like that DSP JBL you linked. You would need something with some processing ability since the factory deck outputs are usually very wacky with all kinds filtering in place, 8-10 channels would be ideal. Typically dsp capable amps of that caliber are pushing upwards of $2k..

 

The 4086 from JBL that I think was linked before and which google results show is a common in place upgrade for these car systems is under 1k and has 8 channels. That's an option.

Im sure if you trawl enough on the internet, someone would have released the software that these OEM amps can communicate with to tune them.

 

Receptacle synonymous with female port. We will get a clearer idea once I get the cable and try it out.

There is a good chance that JBL/Harmon use 1 digital signal processor in multiple amplifiers packaged differently. The JBL DSP4086AM price point is likely lower due to the minimal chassis or case. The one the Prius came which sells for over $1k comes with a big piece of metal attached which is probably a giant aluminium heat sink and will probably extend the life of the amplifier by keeping the temperature down when under heavy load.

 

FWIW, I have discovered that for my Gen 4 JBL system on my blue 2021 Prius Prime Limited, the best setting is the default, flat equalizer setting. If I just set everything in the middle, I get the best sound in most conditions.

Overall, I am fairly pleased with JBL. It could always be better, but it is pretty good for music listening. Most of the time, I am limited by the transmission quality of Sirius XM anyway.

Regarding your problem, note that different audio sources (bluetooth, radio, satellite radio, etc.) have different sound-level presets. Moreover, the problem you are having might have to do with your phone or some software update than the JBL amplifier itself.

 

They've done sufficient troubleshooting and others have chimed in to point out that its not the phone, and if it is software, it's related to the way the audio signal is processed. Given the amplifier will do signal processing, and that this is offloaded from the head unit (because it's own internal amplifier and DSP is going to be bypassed so signal goes straight to amp), then the issue - if it is software - is amplifier related on it's DSP settings in some way.

And FWIW the audio sources do have different lossy compression tied to them. But if they are using wireless AA or Carplay, those signals are lossless format. So they pass on whatever the app is doing, and the app won't be doing anything as it relates to filtering the audo channels in the car to various speakers - which is the specific issue they have. The rear speakers are getting a heavily attenuated signal and along a significantly narrower range of frequencies than they want. In a traditional aftermarket audio setup you go to the amp to change things there in terms of gain/EQ, with more advanced models offering much more complex EQ tuning on a per channel basis. In my old car (before a crossover broke after many years of valiant service not worth fixing now), I had a simple 4 channel amp with simple gain and 3 band EQ for the speakers, as well as optional high end attenuation switch on my kicker KS crossovers.

 

FYI, the head unit sends separate front and rear signals to the amp. The amp then splits the signal further to different speakers.

I'm just saying that getting control of the amp might not solve the problem if the head unit is feeding a very low strength signal to the amp on the rear channels. Before spending a lot of time and money trying to crack into the amp, I'd first make sure it's going to be worth the effort.

 

Interesting, so, it's also the audio quality—not just sound level.

And resetting all the audio settings doesn't help?

I think I have DSP turned off in JBL in my 2021 Prius Prime Limited under the audio options.

 

I had the equalizer adjusted in my Gen 4 JBL for louder bass and louder treble and quieter midrange for a long time. I then tried to optimize around those settings. I was never pleased with it. I finally decided to adjust everything flat, and ever since I did that, I've been pleased with the sound of my Gen 4 JBL system.

It sounds like the head unit might have some bugs. The Gen 5 head unit a US-designed head unit. But if that's the case, then the non-JBL owners must have similar issues. The larger Gen 4 head unit is a Denso, and the smaller Gen 4 head unit is a Denso Ten.

 

Curious to hear if it lasts. I turned everything extra off like speed sensitive volume. I did notice some inconsistency in the volume levels of the car alerts early on but that seemed to had resolve itself. On my android phone I have spatial audio turned off , and HD audio over bluetooth turned on. (pixel7)

Have you tried playing from a USB drive to see if the issue was consistent with the phone out of play?

 

I have verified that DSP (auto sound leveling) is set to off and the equalizer (bass, mid-range, and treble), balance, and fade settings are all set to the middle position in my Gen 4 Prius Prime JBL.

 

What player are you using? I use Poweramp. It has convenient built in EQ, I rarely use it but it comes in clutch on some lesser produced stuff I like to listen to.

What have I done to the Prius? Nothing too intense yet, just added a sub and replaced the dash and JBL tweeters. I've been waiting for the weather improve to dig in more. I'll be doing some extensive sound deadening, upgrading the door speakers, building an enclosure for a bigger subwoofer, and then rewiring the whole thing though a processer/amp. I always build up the sound system in my vehicles. I never liked the JBL so I started formulating a plan to replace it immediately.