Socalsteve...thanks for the reply.

It sounds like you went from PCM/Bose Amp/Bose Speakers to Aftermarket Headunit/No amps (exception sub)/aftermarket speakers. Did you do a interim step where you upgraded only the speakers? I am still looking to understand quality of PCM output. If you changed PCM+Speakers+cut bose amps out of the loop you changed three things at once...logical from getting your stereo upgraded...but doesn't prove PCM was the culprit.

Anyhow, I am interested to see how this thread develops. If I can find a solution to improve sound while maintaining stock look (and not spend too much...as people have noted, this is not the car to dump thousands into sound system) I will likely upgrade.

 

From reading Steve's thread and last post carefully, you would see that he only replaced the PCM headunit. He kept the stock speakers, and bypassed the Bose speaker amps and ran the speakers through the Pioneer's internal amp. That's why/how he concluded that changing the PCM out alone would make a positive change in sound.

 

I read Steve's thread on the change out and all he did was change the head unit and bypassed the amp, and that is what I will be doing first. Also, in his thread showing pictures of the process you can see the finished result looks very stock. To me its a no brainer I can take the brand new in the box PCM I will be picking up from the dealer, place it on ebay, and with the money purchase the new Pioneer AVIC-X920BT. When I initially asked the dealer about adding the OEM Navigation DVD when he swap out my head unit it was an additional $2500, and that's what got me to thinking. With the Pioneer I will be getting a nicer sound, bluetooth, navigation system, DVD player, etc. and there is a local dealer that does the swap all of the time and quoted a price of $1850 installed including factory look faceplate, so for relatively the same price as the head unit alone I will be getting a nicer unit plus navigation. Seems like a no brainer.

 

Please carefully read both my threads. You will get your answers there.

Never changed out the speakers or sub. Nor the Bose sub amp. For as noisy as this car is, it doesn't sound too bad and was MUCH cheaper than replacing speakers.

Unless you are planning on listening to this in your garage, with the engine off and you have a digital processor to shift sound waves to compensate for the sound field (that you are not listening from a center position), all the upgrading you will do will be lost.

Its a noisy small car, not your living room where you have total control over the acoustics. Maybe the best solution would be to take out the back seat and add acoustic sound deadening material and then find the quietest tires you can...This would truly help the interior deal with high end sound....short of that, dont bother.

Good luck!

Steve

 

[quote=muerdeme;2799348]"How do you know that the head unit is putting out a flat audio image/signal across the range? You dont. Maybe the speakers are perfect and the signal going to them is whats flawed...

The PCM is crap, plain and simple. The output signal it generates is crap. All you do to change the amps, speakers, x overs, whatever will not change the fact that signal being output is crap..."


This is the reason that you grab the signal before it gets to the PCM, then you are basically using the pcm for controls and the signal is fed from the optical input prior to the amp, which then takes on the characteristics of the processing of the Motus piece.

 

[quote=ulmpharmd;2799569]This is totally confusing. The PCM is what is generating the signal. Then to the amp(s), then speakers. How can you grab a signal before its been generated?

Doesn't the CD player have to generate a signal? Radio, etc? You are not talking about components here. The pre-ampp, cd player, tuner, etc is all built into the PCM.

Please explain how you do this.

Thanks,

Steve

 

From what I've heard, the PCM unit from the Bose cars does some active reequalization of the output signal variable based on volume or car's speed, which is why replacing it for some it sounds better. The PCM unit from the non-Bose cars does not re-equalize the signal. So that, combined with a small high power class D amp such as a JL HD600/4, good Focal separates (I am using a pair of 165 KR2s) and a 8" subwoofer in a tiny 0.2 c.f. box (Image Dynamics ID8) sounds very good without adding a lot of weight or taking up any more space than the factory sub.

 

You can turn this feature off on the PCM 2.1 Bose equipped model.

I bet if you replaced the PCM with a nice double din head unit, you would be amazed at how much better the sound quality would be, especially since you have already upgraded the amp and speakers. And, you would have a 7" touchscreen, updated nav, XM, bluetooth and ipod integration.

To me, it was a no brainer.

Steve

 

Here is few pictures i took during the test.. As you can see i placed the mic at driver's ears position. You can see the RTA curve from 25hz to 20khz, so basically all 10 octaves human ear can hear. It's 4db step, so each dot step represent 4db (it's a lot).
The low frequencies curve shown is in 1db step (higher resolution), you can see the peak at 50hz and the major roll-off starting at 63hz (typical bandpass enclosure effect).

 

jon8, thanks for all your professional analysis. You've given me great peace of mind as I no longer will waste my time trying to do the impossible getting it to sound right.

 

I can confirm: there is no satisfactionary Treble/Bass/Fader/etc.. adjustment possible. However, on the RTA the best results i had so far is -2 Bass/+2Treble/No surround.

So instead of a sound quality of 2 out of 10, you get 3/10

I have few ideas to improve it to, let's say, 5/10. By just changing few speakers (sub-500$ mod) but i need to confirm few things before (this week).

 

Good point, Steve.

I don't know, for now.

It's pretty easy to test the OE speakers, all i need is to remove them and test it with (quality/neutral) external source. I may also test the T&S parameters, but most important would be the impedance and sensitivity.

Then, i can also test the amp's signal to see if there is any EQ (unlikely) or crossover (most likely) on each channels. That kind of information is essentiel if i plan to change the speakers (i don't want to damage the OE amp nor put unprotected tweeters/mid). Will i need passive xovers ? We'll see.

The sub will be challenging. It's one of the worst subwoofer system i ever heard in my whole life, and i've seen a lot. The tiny bandpass enclosure makes modifications very difficult; you can't change the transducer as you want, the enclosure/air ports are tuned for it. And it won't give low-mid, ever... Maybe up to 80hz if i'm lucky.

 

lol

thats what i found out to be the best sound... in the garage.

https://www.6speedonline.com/forums/...l-setting.html

when i was driving, the bass was drowned out so i had to raise the bass level to +1

 

The "drowned bass" feeling you experienced is probably coming from the end of 2nd and 3rd octave dip (mostly 70hz-140hz) which is the "punch", snappy and full bodied effect sound area. Like i said previously, i highly suspect the noise of the motor/road to be conflictual precisely where the sound system's frequency response is weak.... Maybe Bose/Porsche designed that on purpose so you can hear the motor ?

what makes bass adjustment difficult (read: impossible) is when you add (+Bass) it makes the peak even worst but helps on midbass. Negative adjustement helps reduce the annoying peaky 50hz but reduce at the same time an already weak midbass (so it sounds "thin")

Treble adjustment; while possible to compensate a bit for natural 8khz roll-off, it makes the midbass sound even weaker... And the natural sonic caracteristics of whatever tweeter/mid there is, doesnt like very much EQ correction anyway.

What i'll try to do is very simple: get a good natural frequency response just by using carefully chosed and measured speakers. Just trowing Focal, MB quart or JL's speakers in the doors is not an answer here. Everything must be measured and planned as a whole.

 

jon8, you're my kinda guy! Being in the music field I took at RTA and did the same thing....yep Bose is uterally HORRIBLE!

Only way to really fix it is to rip it all out.

I learned so on my 2009 I did not order Bose...just the stock system. It's not all that great either but better than spending $1800 on Bose. I can take that $1800 and do a much easier upgrade to the speakers in the door and add an amp and that system will out perform the Bose easy.

Best of luck!....funny looking freq graphs with the RTA huh?...they also change as the volume goes up and down....odd stuff for sure! There is compression also in the Bose system.

Remember No Highs - No Lows - Must be Bose! Great marketing and sales company but horrible sound company.