[Manticore]

Sorry, my source is licensed. You can do a Google search for "Pink Noise" and find multiple sources quite easily. Just download to a thumb drive and you're good to go.

 

[Manticore]

I'm not as tech savvy as you are, so how do i take SPL readings?
Did you find the Meridian rference, which I believe to be very important!

The forum member who corresponded with Meridian is on the Reddit KiaEV6 site
This way to Reddit
He is the original poster on the thread.
To answer your other question, you need a piece of test equipment called a dB meter.
You really don’t want or need to go through this process, but ill describe what I did.

First you must create a reference recording in stereo of pink noise recorded at 0 dB. I found a reference source and recorded a 30 minute track of pink noise sampled at 320 kbps (the highest sampling rate the Meridian can process). I then turned off all processing and set the eq’s to flat. I centered the balance so every channel was receiving the same signal level. I decided to use the front center speaker as the reference, and turned the volume up until the SPL meter read 75 dB. The meter was then moved to each speaker in turn. The meter was held by a tripod and placed equidistant and on axis with each driver. A minimum of 5 readings were taken from each speaker and averaged.

One would expect all the drivers to be relatively close in level because each was receiving a signal of the same amplitude. The actual results, however, demonstrated significantly lower program levels across the rear woofers (-7 dB), rear tweeters (-12 dB), surround speakers (-15 dB) and the subwoofer (-20 dB).

On the decibel scale, the smallest audible sound (near total silence) is 0 dB. A sound 10 times more powerful is 10 dB. A sound 100 times more powerful than near total silence is 20 dB. A sound 1,000 times more powerful than near total silence is 30 dB. So the difference in Sound Pressure Level (SPL) of 20 dB between the front center speaker and the subwoofer when both are presented the same signal is quite profound.

I’ve provided all this information to KIA, and I’m anxiously awaiting their response.

 

[Manticore]

The other EV6 did not sound the same. Much more sound volume / punch from the back speakers...didn't really notice if the sub was louder too, as we got out of the car quite quickly after the dealer realized something was wrong with my car
I asked for the build date of mine, and it was built around 23. july 2021, so not even under the SA520 TSB to change the subwoofer.

My dealer has applied every “fix” Service Bulletin related to the audio system to my car; yet none have done anything to make a difference. Once you have played a calibrated signal through every channel simultaneously, then take SPL readings at every speaker which clearly demonstrates the reduced volume, it’s kind of difficult to claim it’s normal. The problem is, there is absolutely nothing a dealer can do to fix this at the current time. Somewhere in the head unit is a line of code that is attenuating the rear speakers output, and a software update is the only way to correct it.

As frustrating as this is, I realize that the dealer is stuck between a rock and a hard place. Until KIA develops a fix, the only cure is to add a powered sub. This only solves half the problem, however, because the rear doors and surrounds are still suppressed. Since bass is largely non directional, the powered sub masks the reduced rear channel output.

 

[Manticore]

Well...i got impatient as always, and went to my dealer.
We sat in the car and played around with the fading options etc., and also uncoupled the subwoofer etc.. Of course his first reaction was to say that "this is probably just the way it is intended to sound"!
So i suggested we tried any other car in the showroom or on the lot, just not another EV6. He then proceeded to choose a new EV6 with the Meridian sound system, but after sitting in that car for 30-60 seconds, he booked me an appointment a couple of weeks from now.
Lets see where that takes us, I will get back to you on that

Glad to hear it helped. I need to search for the Meridian reference, it is on this or another forum. In it, the representative made clear there should be no difference between the level of the front versus rear speakers. I’ll get back with you on this. Did the other EV6 sound the same? The difference is readily apparent no matter what other Kia model you compare.

 

[Manticore]

@Manticore, thank you for your explanation. these are the kinds of insights I was looking for. The whole muting thing is so odd. In my other (ICE) car, the sound system will occasionally get stuck in ducking mode, but a quick full power cycle will fix it.
Dont get me wrong, I still love this car, but ducking Kia and their ducking sound engineers really need to get their ducking act together…

Thanks!

It kind of leads me to believe the production line testing (if there is any at all) is limited to “can you hear it?” or a “go/no go” evaluation. Evaluating the sound of speakers is highly objective, and when you have an underperforming one…well let’s just say it’s very difficult to convince someone who doesn’t have a trained ear that there is a problem. To a lot of people the stereo sounds great. To others it sounds acceptable. But the audience for this car is not your typical buyer. EV6 buyers are more likely to have had luxury or high performance cars as predecessors, so they come in with high expectations. When I first heard my EV6 stereo while still at the dealer I immediately sensed something wasn’t right, but I was confident it was some oddball setting or eq issue. But once I tried to setup the stereo I quickly discovered that something was very wrong in the back of my car.

 

[Manticore]

@Manticore - your input on this subject is simply brilliant and much appreciated! I've got a "big gun" coming next week.

Hawk:

Thanks for your kind words. I'm willing to bet the "big gun" you mention is an understatement.

Instead of spending any more bucks on my EV6, I'm using those funds to add 4 more channels of amplification and speakers to my home theater, taking it to an 11.2 configuration. But I'm envious of what you are doing. I made my decision based upon anticipated hours of use, and I spend way more time at home than in my car.

 

[Manticore]

You are on the right track. Moving the fader towards the rears will improve the overall sound because what you are really doing is reducing the level of the fronts to more closely track the rears. When you move the fader rearward, the rears don't get any louder at all; you are simply trying to achieve a reasonable balance in the relative volume between front and back. I've got the rear balance fader about the diameter of the "knob" towards the rear from the center circle.

(The top of the fader just touches the bottom of the center circle) Try to use some bass heavy program material to make this adjustment. SiriusXM Channel 53 {Chill} is a good bass heavy source. Also, ONLY USE THE REAR ARROW to make this adjustment. If you deviate at all when moving the fader, the rears will immediately drop out. (That's the muting kicking in.) If this happens, touch the "Center" target to restore the rear channels. This unwanted behavior really demonstrates how the muting function works improperly.

Once the levels match (as best they can, it won't be perfect), you then use the volume control and the rears will track. What you are doing is reducing the fronts to match the rears. Because the fronts will now track the rears, volume changes will be better, but you will be using a much higher overall volume to overcome the muting (reduced but not off) that is stuck on the rear channels. You'll be pushing the amplifier harder to overcome the reduced front levels, but the rear bias you have added will make the overall sound much more balanced.
Observation: Using Surround mode adds in the two high mounted rear surround speakers. If and when the onboard navigation speaks, or receives a text notification, you'll hear it loud and clear through the surrounds (if in surround mode) because they unmute momentarily to make the announcement.
Meridian designed the system to automatically reduce the level of your chosen source momentarily so you can hear the navigation or other warnings when they occur. I'm calling this muting, but the proper term in professional audio is ducking. The primary source volume drops (it "ducks" down but isn't silenced) so the warning can be heard. THIS is the underlying problem in the head unit. The rear channels are stuck in this ducked or muted state.
I have documented this anomaly and sent it to Kia Customer Service.

I have had long sessions with the Service Techs at my dealer, including a Kia Certified Master EV Tech (who I don't fault at all) and they fully understand and agree this is a problem. But there is absolutely nothing they can do because the problem is going to require a software update. Kia has tried multiple fixes for this including replacing the amplifier, (which doesn't work) because the problem is in the head unit.
If you need to prove this to your Service Writer, get them to sit with you in your car and do the setup process I described earlier. Then ask them to do the exact same experiment on any other new Kia on the lot (any model they want except another EV6). The problem is immediately evident. Your service department can't fix it (yet). The only other workaround is to use the "big guns", and install a powered subwoofer. This instantly improves everything because it can amplify the muted output from the EV6 external amp. This is why multitudes of EV6 owners are taking things into their own hands and bringing in the "big guns” and instant nirvana a powered subwoofer provides. This solution is best for the the front seats, but rear seat passengers will still have muted rear doors and surrounds, (but plenty of bass). The intended Meridian experience fails to materialize. The Meridian factory installed subwoofer is actually quite capable, (if it weren't getting the muted input). It is actually biamped; the single woofer has two voice coils and each is fed by it's own amp channel. But it can't deliver anything when it's getting a muted signal. This is why the Meridian system can't deliver as it was designed. Meridian has gone on record that the level of the rear channels should match the front channels. But I doubt if any Meridian engineer has ever sat in a production EV6. If they did, they would be horrified. But Meridian has no support network at all for their automobile products, there is no mention of any automobile product on their website. Only Kia can fix this, and I'm confident they will eventually actually listen to what is rolling off the line. But for me, I choose to wait for the fix. The audiophile in me disagrees, but the way I look at it, I shouldn't have to add a powered sub to a $50,000+ car just to hear what was intended.

 

[Manticore]

All it would take is 2 more channels of amplification. Connect the new amplifiers between the existing amplifier and the rear speakers.
You would probably be dissatisfied however.
That's because all the rear channels (mains, surrounds, and the sub) are muted. (Not Off, but down by 20 to 30 dB). You would still need a way to make the rear channels "track" the front channel levels. Otherwise you would have to be constantly adjusting the rear channels output levels to track the front.

None of the TSB's Kia has issued relative to the subwoofer have corrected this problem. I'm holding out for the KIA fix as I don't think I should have to add an amplifier to make my rear speakers audible. Going the powered subwoofer route makes a tremendous improvement, but it doesn't solve the rear sides and surrounds being muted. Meridian has gone on record that the rear channels should have the same output levels as the fronts, but I have yet to hear the rear speakers work properly in any EV6 I've tested. Meridian didn't manufacture the KIA sound system, they designed it. But your head unit was designed by KIA. Kia makes it interface with all the sensors, radars, cameras, audio sources, radio, phone, Bluetooth and internet signals to keep the car on the road and the driver entertained. There's a tremendous amount of processing going on in that head unit. But somewhere deep inside there's a bad line of code, and so far, the engineers haven't found it. When they do, you'll be able to sell your powered subwoofer on eBay.

 

[Manticore]

The four wires you have coming from the KIA amplifier are the inputs to the subwoofer. The subwoofer is really biamped; it combines the outputs of a left subwoofer channel + (brown) with the right subwoofer channel + (pink). The white wire is the left channel subwoofer - (white) and the red wire is the left channel subwoofer -.
Summarized: (all are high level outputs)
Brown Left+
White. Left -
Pink. Right+
Red. Right -

You need to determine which wires on the kicker harness are the subwoofer inputs and connect the above outputs to those inputs.
You'll need to refer to the Kicker documentation to determine which wires are the high level inputs.

 

[Manticore]

Super interesting! Did you by chance run that test at multiple system volume strings to verify it’s a constant -20dB, vs differing with volume?

Yes, but I have run so many tests I don't want to overcomplicate things. Suffice it to say if I set the front center to 80 dBA, the sub would also increase by 5 dBA, but the difference remains constant.
I should also note that the level difference is not -20 dB for all the rear speakers; only the subwoofer demonstrates that big of a difference.
For example, the rear surrounds were down by -15 dB; the rear door tweeters were down by -12 dB. The differences start at -2 dB for the front tweeters and gradually increase as you move backwards. Also, turning on Meridian Surround mode increases the rear surround output (but only those 2 speakers) further complicating the problem.
I chose to present only the unprocessed, totally flat signal to insure every driver received exactly the same signal from the source. The differences exhibited are totally outside the operator's control, and Meridian has gone on record saying there should be no difference in perceived volume or quality between the front and rear speakers.

 

[Manticore]

I bought the JBL BassPro SL2, and i'm disappointed. It's either too boomey, or you can hardly hear it except for a narrow band of bass that thumps. It's so unnatural. The output from the Meridian amplifier is clearly not a flat frequency response. I guess it's running through a DSP to try and extract as much bass from the original passive speaker as it can, and the JBL is not matched. Yes, I fiddled with all the controls on the amp. Bass boost down to zero. I brought the JBLs remote level control to front, and you have to adjust it all the time to match it to the material your listening too.

Does anyone know if the Meridian amplifier has a spare line level output?

No, it does not have any line level outputs. It's inputs are all digital. Most people are utilizing the existing 4 wires coming from the amplifier. EV6 Head Unit Sheet 1
EV6 Head Unit Sheet 2
You should note that the AMP has 2 output channels, and the Meridian Sub employs a single woofer. The woofer has dual voice coils and since it is really bi-amped it is actually capable of some commanding output when the output isn't muted by -20 dBA.
I was an audio engineer in a former life and have taken SPL measurements from every driver using a calibrated pink noise source. Not only are the subwoofer outputs muted, but so are the rear door speakers and the surrounds (unless Meridian Surround is ON). So if you really want to solve all the ills on your own, you should consider adding amplification to the rest of the rear drivers.
The current KIA TSB's 494 and 494A for the Meridian AMP don't address this problem at all, but it is a widely complained about issue. My dealer is totally convinced on this issue and he has observed the same problem on EV6's received this month, so it isn't limited to early production cars for the US market.