vucelick

I have been lurking here for a while, and recently picked up a TL. Soon after I noticed that when I played standard 2 channel cd’s in the TL that they did not sound near as good as the demo DVD disc that came from the factory, given that the DVD disc can contain a great deal more audio information, I thought that it was normal to hear a difference.

Upon a closer and more directed listening session, with standard 2-channel cd's, I noticed a distinct lack of mid-bass coming from the front speakers, much less than I anticipated should have been there (even for inexpensive factory drivers). I was trying to get the car to play 2-channel stereo in a more classic sense, where the left and right channels create an image sweet spot in the center of the dash preferably projected out in front of the car a bit, similar to what a good home stereo system can do. I consulted with a friend and fellow “stereo guy” who quickly came to the same conclusion that I had.

We tried to ascertain if the crossover was an active one in the amplifier, i.e. electronic, or if it was a passive one, i.e. capacitor and coils wired in with the speakers, or if the head unit itself was applying some kind of signal processing/crossover function.

What we found is that if you fade the sound completely to the front, the deck shuts of the sub off completely, and the front speakers are crossed over very high and lack mid-bass. Additionally, and more importantly, we found that the center channel is wired such that if you shut it off completely the head unit allows a more favorable front crossover point that gives some nice mid-bass to the front speakers, with front speakers set to a +2 or +3 front bias, and the sub set to +3 to +5, and the bass setting a center or + 2 to 5 (depending on the recording), you get a nice projected center image with nice, accurate sub-bass...for a stock system.

Try it by fading the front to +3 with a well-recorded 2 channel stereo disc, then listening as you turn down the center speaker all of the way to -6, then click it the next click to “off” and listen to the crossover frequency change to a more favorable one with quite a bit more mid-bass. You can just toggle back and fourth between -6 and off the hear the difference.

CYBERTIGER 718

wow! That Is A Great Finding. Thanks For The Info. Just Got My Wdp Today. I'm Going To Try That Now Thanks Vucelick!

Republican TL

good work. I have been messing with the settings too but not as much as you have!! Nice research.

Lore

This is odd - a few months ago someone posted that you should have all settings at dead center except for the BASS which should be set to -2. Here it sounds like we should increases all the biases (as listed). For true sound, who's right?

vucelick

I think that the bias is mostly a personal opinion and very much dependant on the type of recording on the CD, however the crossover switching that occours when shutting off the center channel, and the fact that it shuts off the sub completely when you fade it entirely to the front shows that some signal processing/crossover shifiting is occouring. I believe there are benefits to the front soundstage when listening to 2 channel audio cd's and XM/FM with the front crossover frequency at a lower hz.

JetJock

Thanks for the info...it's great that we have people on this forum that do more than complain about rattles. Great job!!

svtmike

I was listening to a stereo DVD-A made from CD source today (I can't hear any difference between them, BTW), and I tried this. I couldn't hear any audible difference between the C-6 and C-off positions.

Mike

kosh2258

What you describe sounds suspiciously like the effect created by the matrixed quadrophonic systems back in the 1970's. An early and failed attempt at moving beyond stereo. These systems derived their back channel information by playing some games with crossover points and speaker wiring schemes.

It wouldn't surprise me if Panasonic is using some methodology to synthesize a multi-channel effect from stereo material. Playing with speaker levels or turning them completely off perhaps switches this effect on and off.

I will have go do some playing because I have observed that certain CD's don't sound all that great in the TL but sound great on my home system.

Good observations, and thanks for the tip!

vucelick

I noticed that the change is not as noticable with the source set to FM or XM, and with certain CD's it is difficult to hear a dramatic difference undoubtedly due to the wide variation in cd sound quality and recording techniques. As is the case with audio what sounds good is usually totally dependent on the listeners preferences.

I used the Donald Fagen cd with "I.G.Y." on it, the same as the demo DVD-A, and found that when listening to the CD with all of the settings "centered out" and the sub at +3, it sounded very thin and hollow, similar to insufficient amplifier power. The DVD-A on the other hand, sounded very good with the "centered out" settings. I checked some other cd's and found similar sound quality improvments. This is of course only my opinion.

kosh2258

Yes, this coincides with what I found tonight as I played with the sound settings you described. The change in mid-bass as you cycle the center on and off is subtle on some CD's more distinct on others. That probably has to do with tracks that have more mid-bass content in the affected frequencies.

I also noted the change in soundstage with the center speaker off, the staging spreads out and gets more definite. Panasonic is most definitely deriving a virtual center channel for stereo recordings when they probably should be turning off the center speaker for stereo material. The virtual center channel they're creating is mudding up and narrowing the soundstage. I did find it odd that they shut down the subwoofer when fading to full front, however.

After making the adjustments you suggested a couple CD's that didn't sound all that good before sounded a lot better on the system - fuller, with more authority. On the CD's I tried I found that center off, -1 on bass and +3 on the subwoofer, with a 3 notch bias to the front speakers gave the tightest overall bass response. But, as you say, that's primarily a matter of preference.

"The Night Fly" is a good reference album since it was one of the first works done in an all digital domain and Donald Fagen is known as a perfectionist when it comes to his work and post production. You can bet the farm that the CD mastering was to the highest standards of the time as was the mastering of the DVD-A version.