JBL Premium Audio System uncovered

Unplug the Amp (at the amp, so you still have a connector plugged into the head unit).

Reboot the car.

You may need to place a load (like a test light) between pin 3 and pin 20. If my theory is correct, this should trick the head unit into thinking there is an analog amp connected.

(There are no wires in pin location 3 or 16).

Next, check for signal from pin 8 to 16. If I'm right, this will now give a variable output signal.

I don't know if this will work for sure, but it's worth a shot.

Nate

 

OK, so since I already knew that shoving the audio about three notches to the back and cranking it to 50 when something good was playing sounded best, what's the summary of a fix to make it sound better at lower volumes? Expensive will have to wait until next tax return, because this one is already pre-spent...

 

i unplugged my center yesterday. The audio system is much more clear.. however the stock tweeters suck... so.. it sounds like sh** because your highs seem to sound very capped. they only go sooo high *shrug*.. that crappy center muffles up the sound but supplies a mid/high sound that makes the stock system sound more full.

i now know for sure that i need to replace the speakers....

 

Now, if the only thing preventing removal of the JBL amp is that you lose volume, fader, balance, and tone control; if you were willing to give up steering wheel control of volume, and touch screen control for the rest, couldn't you replace the JBL amp with a equalizer box that has a master volume control and most any other amp?

Something like this Clarion eq? (although something with lighted dials would be nice...)

If the beeps are generated in the JBL amp, those would be lost (all together now: awwwww), but is there anything else that would be lost that I'm missing? Would the bluetooth handsfree and the nav voice still work?

 

<div class='quotetop'>QUOTE(FourOhFour\";p=\"73340)</div>

Wouldn't the signals for volume, balance, fader, and tone still be available? If so, an enterprising person could design a circuit to capture them, recode them, then relay them to a preamp that accepts remote control signals. Actually, of those the volume is the only important one - the others would be _easier_ to control via a remote in the cubby than they are via the clumsy MFD interface.

I don't know which would be the bigger benefit - the better sound, or the elimination of the damnable beeps.

Also - how does the JBL amp know to beep? is it decoding a comand, or is a "beep" signal coming in on some control wire? If the latter, maybe one just cuts the wire ...

 

First of all, let me state that this discourse is above my level of knowledge, I know nothing of audio systems.

But,

I use my cell phone for business use quite a bit and the quality of the hands free call is important to me. I have had aftermarket hands free systems in other vehicles before, and the one in the car beats them by a mile, the voice of the caller can be heard quite clearly to me. Now, they sometimes have difficulty with hearing me, projecting my voice towards the mike on the roof centerline helps, along with the new tires and the noise reduction they bring.

I have used the NAV system for more than I thought I would, its great, works well, and I can hear it quite well too.

Those are all midrange sounds and the high end/low end does not mean that much to me for music purposes. Nowhere in this present discussion is the quality of those midrange voice communications addressed.

What are the ramifications for voice with these improvements?

Thanks

 

The hands free is coming straight from the NAV ECU under the driver's seat straight to the driver door lower speaker. The NAV intercepts speaker output from the JBL. However, the NAV does also send a mute signal via a dedicated wire. I forget at the moment if the mute goes to the header or the amp, but I believe it was the amp.

 

<div class='quotetop'>QUOTE(DanMan32\";p=\"73551)</div>

I think the mute signal goes to the head unit, as the tape deck pauses when you are on a call. (It may *also* go to the amp, but I don't see why.)

 

Okay, Sorry for these questions, but I cannot tell from what has been posted already if....

1. One can disconnect the front center speaker by simply lifting it out and pulling (and taping?) the wires from the back of it and....
2. Whether this will make a difference (in the ears of you experts) in the sound quality.

Any thoughts would be appreciated!

Rick

 

I am haapy with the sound from the Premium 6 CD JBL Changer, however I can't figure out how to view the data i.e. names of the tracks on the screen. Is this a bug or does the six cd changer on the 2005 Prius not have the ability to display the CD data?

 

<div class='quotetop'>QUOTE(pforde\";p=\"73814)</div>

See V8Cobrakid's post above regarding his experience.

 

How can I disable center speaker?

 

One of the things I really miss from my Acura RL is the Bose system. Is it possible to take out the JBL system and have a Bose installed?

 

.. i wonder if my parents would notice me swapping the Cadillacs boss system with mine.... lol

that car has a really nice enclosurless sub

 

Thanks so much for doing these experiments and sharing them with us. I was on the verge of doing a similar experiment and you've saved me lots of time.

I'm trying to figure out how to interpret your results... particularly the low frequency response. I assume you are judging amplitude on the woofer measurements from the height of the peak on the lower right graph, and judging the frequency by the horizontal position of the peak. It looks to me like the front woofers and rear speakers go almost to full amplitude somewhere around 35 Hz, not at 70Hz as you wrote. So perhaps you can explain what I missed there.

I did notice, especially on the rear door avi, that the amplitude does seem to be higher near 70Hz, but only by about 15% on the vertical scale. I'm assuming that is a linear not logarithmic scale on the vertical, so 15% is not very much, just a decibel or two. Not too significant in the grand scheme of things.

I'm also curious about the poor signal you observed from the tweeter signal. How were you driving the bose tweeter when you experienced the poor sound...

- Connected directly to the JBL amp? If so, impedance mismatches may have been a problem if the bose tweeter had a different impedance from the factory one. IUnlike aftermarket amps, the JBL amp wouldn't be designed to drive any different impedances besides that of the factory drivers.

- Connecting the JBL amp tweeter output to the speaker input of an outboard amp? Again impedance mismatches are a possibile explanation for the poor sound, but less likely.

- Did you have a passive crossover in the picture? I doubt it, but if so again that could cause an impedance mismatch if connected directly to the JBL amp.


Your results are very helpful in that they answered one question I was very interested in: Whether the front woofers have any low pass crossover on them. From your results it looks like they have a shallow (6 or 12 db/octave?) low pass crossover, starting probably around 3.5k. I had a hope that perhaps there was no crossover on it, which would mean we could just take the full range signal from the front woofers to drive a set of passive crossovers for aftermarket speakers. But obviously that won't work since the front woofers have low-pass.


So it seems that the only feasible solution is to do what you have done: Take the signals from the JBL amp outputs that drive the rear speakers, into the speaker level inputs on an outboard multichannel amplifier, and drive brand new drivers from outboard passive or active crossovers.

Did I understand correctly that the following is that you did...

JBL amp rear door outputs drive all the following:
An outboard amp that powers a passive crossover, which drives front tweeter/woofer.
The rear speakers through the factory passive crossover.
An outboard amp with low pass active crossover that drives the subwoofer


The volume and right/left balance controls on the head unit will still work. You would have to adjust the fader on the outboard amp itself, but that should be fine. Center channel would have to be disconnected of course. The nav system would have to be left in the loop for the new front speakers, so that the outboard amp sends a signal to the nav inputs, and the nav outputs are what drives the new passive crossover for the front. This would likely improve high frequency sound quality of telephone calls as a side benefit since they would use the tweeter as well as the woofer.

Note that we probably can't use the front JBL amp output woofer/tweeter signals in any case, because they presumably are tonally balanced with less midrange and high, to compensate for the mid/hi that normally comes from the center channel. So more and more it's looking like driving from the rear JBL amp outputs is the only way to go.

There's only one concern I have with this approach. Ideally, a manufacturer will customize the frequency response of each channel in order to produce the best sound in that particular cabin. So the JBL amp may be tailoring the rear outputs for the rear cabin, and the front outputs for the front cabin. Given the overall level of ineptness in this sound system, I don't necessarily think they have done this, but if they have it might mean that we can't get great results. I suppose the only way to find out if this was done is to do very high resolution frequency response tests on all channels, or perhaps some data mining from the tests that you've done.

I'd really like to know about the low frequency measurements and how you got the 70Hz figure from your attached results.

Thanks for your work!

 

first of all, thanks for sharing this knowledge SynergyGuy!

The audio system has been my main concern since I ordered the Prius some months ago. (its a business edition with the jbl 9 speaker set and will arrive in two weeks time) Especially I absolutely need some way to play mp3's.
Reading this thread, there three things that come to mind:

1. If the filters in the JBL AVC_LAN amp are software, can't these be reprogrammed to better values? (like uploading new firmware)
2. How would you recommend connecting an mp3 to the amp? does it have standard cinch connectors or do I have to cut wires?
I know there is a comprehensive manual about how to dismantle your dashboard and use the cd changer port, but since my car is leased I don't want to doctor with it to much
3. Has anyone pointed JBL to this thread yet? I think it would be interesting to see their reaction, i.e. how they will correct the obvious flaws in this product...

Regards,
Geronimo

 

If you have the separate JBL amp, you could set up a switch to change over the header audio input to the MP3 player input. Since the amp does all the audio controlling, you maintain volume, EQ, balance and fade control.

You would need an Ipod controller connected to the aux socket of the header if you want more control, such as song list, than that.