DiyMobileAudio.com Car Stereo Forum banner

481 - 500 of 1124 Posts

·
Registered
Joined
·
806 Posts
Discussion Starter #481 (Edited)
Update August 12th, 2013:
After 1 year and nearly 6 months after popping the P99 into the dash I'm still finding new ways to improve the sound. If I'm writing something like this a year and a half from now I should have achieved complete audio consciousness and enlightenment. Talk about your value.
The topics of today's update include a revisit to RTA, a revisit to full-range rear fill, a visit to a reference system and encounters with crossover overlapping and underlapping as well as developing your understanding of what you value in your system's sound characteristics.

1) RTA. I thought I had given up on using RTA as a means to set a basic response curve in favor of using band limited pink noise test tones and adjusting by ear. The problem with that approach is that you have no baseline to work with other than your own memory. Once a basic test tone by ear response was achieved, it was difficult to know how much to adjust which EQ band to adjust the sound according to what it was missing. With a baseline RTA curve you can establish a reference from which to work from and develop. In my recent case the mid range clarity was missing and without RTA (for me) it seemed like I was adjusting blindly and not getting anywhere. So I established a new RTA curve (included) and so far so good.

2) Revisit to full range rear fill. After ditching the rear fill (assuming it was the source of destructive interference / comb filtering, which I assumed was affecting my SQ) I could not achieve a front stage only tune that sounded as good. Just something about the properly time aligned and leveled rear drivers that made for a more open, spacious but still focused sound. It turns out that the assumption about the rear stage comb filtering being the source of my SQ issue was not correct.

3) Reference system. I was fairly ticked off after a recent tuning session revealed that I had a high amount of sibilance and brightness. I played the CD on my home system and found the recording is what possessed the brightness and sibilance. Don't beat yourself up over the occasional bad recording and check your reference system- even headphones / ear phones.

4) Crossover overlapping. Reading about the typical null / cancellation response dip many vehicles exhibit around the 60-70 Hz region led me to try multiple adjustments in order to help fix it. As shown on the RTA, the only measure that was sonically pleasing as well as effective was overlapping the midbass drivers and the subwoofer. Higher crossover points on the sub, shallower slopes, phase. time corrections, etc. did not help or were measurable as was a simple overlap- setting the midbass to HP at 63Hz 24db and the sub to LP at 80 Hz 24 db was both sonically noticeable and RTA measurable.
Being able to do the overlap and then go in and re-adjust the EQ for a smooth bass response (without boosting, which seemed to make "strained" sounding bass when boosting to fill a null). Readjusting after the lower midbass HP contributed to the success of this solution. So far so good.

5) Crossover underlapping. After reading a link in a fellow DIYMA member's build log about a high end home speaker system that makes use of underlapping midbass and midrange crossover points- and relies on the summed response to fill in the valley- I decided to measure the response of my midbass upper limit and midrange lower limit at the exact same crossover point. As measured, each individual driver was playing a shelved response well beyond the crossover point and as such there was about an octave of overlap where the midbass and midrange were playing the same frequencies and at equal level. This can't be good, I thought to myself. So I shifted the HP of the midrange by an octave, then re-measured individual and summed responses. No more overlap and they sum to a smooth response through the crossover frequency. So far so good- it does seem to sound better and more focused- especially vocals.

6) Developing an understanding of what you prefer in your "sound". I'm still doing this. I'm finding that I am starting to prefer uber clarity and openness in the sound with occasionally dynamic (but realistic) sounding bass attacks and less of an overall blurred warmth to the sound. It took some time to realize this- and it is a very specific tonality that has to be right on the money. The sooner you can develop your own specific sound preference, the sooner you will stop chasing your tail from one sound to another. Good luck!
 

Attachments

·
Registered
Joined
·
339 Posts
Does the p99 work with iPhone 5? Also, I understand the p99 does not support the pandora app like the 80prs, but one can still stream pandora (or any Internet radio) through ones phone and it will still play on the p99 the iPhone connection correct?

I did not get to read the whole thread, so, my apologies in advance. I'm just trying to decide what will work best if I pull my oem hu.
 

·
Registered
Joined
·
806 Posts
Discussion Starter #484
Update 8/18/2013.
This is basically a tuning update- how to refine the EQ settings of the P99- and the understanding of equal loudness curves- and how to apply this info.
As an owners of the P99, we are faced with the dilemma of how to achieve the best possible sound quality given the fact that we are "left hanging" with an autotune that does not achieve this goal- and a 32 band EQ with no shelf filters and not easily tuned by ear.
Assuming you have your drivers level matched and the best possible crossover points and slopes, we take the RTA route and wonder which frequency response curves to target. What does my best sound frequency response curve look like?
In the previous update we did some things to improve SQ but were left with an overall harshly bright sound on many music sources- despite a curve many find pleasing. The challenge becomes determining which frequencies to cut and by how much.

I did some additional research of equal loudness curves, the science that illustrates more / or less power (volume) is needed at any given frequency in order for our ears to say they are at an equal level. While you do not want to apply these curves at face value, especially in areas of your system's response that you are happy with, they do illustrate the key frequencies where our ears are most sensitive. Use the curves as a reference for which frequencies to target. For example, it wouldn't take a great leap in understanding to realize that a system with overly bright upper midrange, with pronounced localization of the midrange and tweeter drivers in a highly amplified as well as reflective environment, despite a flat or pleasing RTA response curve, still needs some cuts in the levels of key frequencies in order to sound better.
The equal loudness curves tell you which frequencies to go after.
A very cool link I found is your own personal frequency sensitivity test. This test really helped me to target the frequencies my ears are most sensitive to. Check it out!

Equal loudness contours and audiometry - Test your own hearing

Also, there have been updates since the fletcher munson equal loudness curve was derived. The most recent curve is the ISO (International Standards Organization) curve- ISO- 226 from 2003. Testing equipment has changed big time since the fletcher munson era of 1937.

http://www.lindos.co.uk/cgi-bin/FlexiData.cgi?SOURCE=Articles&VIEW=full&id=17

In my case my ear test matched almost identically to the ISO curve. However, the important takeaway is that the curve is volume dependent- meaning that since your ears are more sensitive at lower volume levels, the curve and therefore the adjustment needed are different depending on volume level. You have to reference the curve at your anticipated listening volume reference at 1Khz.
I took the test at a low volume level and it indicated some drastic differences (e.g. 9db between 1.5K and 4K) Therefore I assumed I would be listening at much higher volume levels ( I picked the 60db @ 1.5Khz curve).
Then I applied these adjustments and derived a new RTA curve between 500Hz and 5Khz, the area critical in my car. So basically I have a slight +3db shelf between 800Hz and 1.6Khz, followed by an evening out below 500 Hz to the typical Andy curve in the bass region, and followed by a leveling out from 1.6Khz to 2Khz, followed by a 3db trough from 2Khz to 5Khz with the peak dip at 3Khz, then a gentle downward slope after 5Khz.
So far it sounds much better, a little bright, but it is in line with my preference.
Next steps might be to make different EQ curves for different volume levels- example a more contoured curve for lower volumes added to an EQ preset (The P99's loudness button is heavy handed IMHO) and perhaps another less contoured curve for when you really want to crank it.

Best of luck in your continued quest for improving your system's sound quality.
 

·
Registered
Joined
·
756 Posts
Just recently, when I press and hold the open button nothing happens. I have to turn off the car and open a door in order to open and remove the faceplate.

Is this a symptom of a bad/dirty/dying ribbon cable or is something else going on?

Thanks for any insights and/or suggestions.
 

·
Registered
Joined
·
1,053 Posts
I like what I read here!

Good job avanti1960 putting everything in black and white!

Subscribed !

.
 

·
Registered
Joined
·
806 Posts
Discussion Starter #489
no problem dudes.
man what an odyssey it has been. my sound continues to improve over time- little changes here and there- EQ, levels, learning what to adjust for what music- every time I used to put on a different CD it was like an adventure how to get it tuned properly. now it may take just a little sub level or balance adjustment and it's there.
unfortunately the "tune" has morphed into shades of a fletcher-munson bose type of clean, smooth sound yet with more clarity and definitely more drama and dynamics.
the issue. is that if you go for a more up front sound, the tune will not work for all varieties of music, so its a compromise- yet a very good one.
the other day i thought i heard traces of your typical lower grade mp3 sound- i don't know what to call it- kind of like a cymbal sound that has a slight warble, delay and blur to it? like a satellite radio signal but not as bad, despite that I play only CDs.
this got me pondering if it could be some artifacts of the digital processing within the DEX. If true, I may be in the market for something else some day- maybe a clarion drz or whatever and possibly a mcintosh- although i believe they are out of the mobile audio biz. their website has deleted all mobile products for many months now.
probably just a bad cd from a starving artist who used bad e-files to cut the CD with!
peace, audio nuts.
 

·
Registered
Joined
·
54 Posts
My biggest problem with the HU is that some (well maybe most) CD's are not recorded that well anymore. Sometime I wish I never upgraded everything so I wouldn't realize how bad some recordings are.

Also the iphone 5s does work with the HU.
 

·
Registered
Joined
·
61 Posts
My biggest problem with the HU is that some (well maybe most) CD's are not recorded that well anymore. Sometime I wish I never upgraded everything so I wouldn't realize how bad some recordings are.

Also the iphone 5s does work with the HU.
You cant blame the HU for technological progess (HU) and technological deficiencies (poorly recorded music media). Its time the rest caught up.
 

·
Registered
Joined
·
806 Posts
Discussion Starter #493
My biggest problem with the HU is that some (well maybe most) CD's are not recorded that well anymore. Sometime I wish I never upgraded everything so I wouldn't realize how bad some recordings are.

Also the iphone 5s does work with the HU.
Agreed, but you can use the P99 to help tune even bad recordings to sound their best. This take some time and patience but it is worth it.
Great recordings tend to shine through whatever tune / RTA curve you are running- often they sound great on inexpensive systems. They will still sound great even when you tune for bad recordings.
Look for tendencies in the sound of bad recordings- a little crispy in the lower treble maybe? Bass a little too hard, predominant or boomy? Midrange too bright? These are all tendencies you can carefully tune out and will make the bettr recordings sound even better.
 

·
Registered
Joined
·
61 Posts
Agreed, but you can use the P99 to help tune even bad recordings to sound their best. This take some time and patience but it is worth it.
Great recordings tend to shine through whatever tune / RTA curve you are running- often they sound great on inexpensive systems. They will still sound great even when you tune for bad recordings.
Look for tendencies in the sound of bad recordings- a little crispy in the lower treble maybe? Bass a little too hard, predominant or boomy? Midrange too bright? These are all tendencies you can carefully tune out and will make the bettr recordings sound even better.
Sage advice
 

·
Registered
Joined
·
54 Posts
I know FM quality sucks but, does anyone else notice the not so great reception on this unit. AM come in crystal clear for news. I listen to FM sometimes and the quality is not so great. I have the antenna amp powered. The alpine 149bt that the P99 replaced had great reception. I also know for a fact it is not the unit as I swapped it with another p99 already. I starting to think the issue may be related to the antenna amplifier being more of a match to the OEM and 149bt head units.
 

·
Registered
Joined
·
806 Posts
Discussion Starter #497
i think the p99's fm is very good- specs are right up there for sensitivity, etc. but i did notice the overall sound quality impression seemed to be as if it was not as good as the OEM head unit. at first it was plain awful but now it sounds much better than original. most of this was due to the systems sound tuning being off so as to exaggerate the worst qualities of the FM signal.
because the P99 is so revealing, you need to be dead on with crossover selection between midrange and tweeter, crossover slopes, and final frequency response.
if your tune is on the bright side, and you have crossover overlap or phase issues resulting in comb interference- the FM can sound horrid- you'll be playing right into the static / multipath distortion sweet spot if these aspects of your tune are off kilter.
remember also that most OEM systems have big frequency response dips in these areas and tend to be bass heavy, basically not even reproducing the frequencies where FM can sound it's worst.
 

·
Registered
Joined
·
54 Posts
One more quirk: When using an iPod (either AAC or alac tracks) the elapsed time bar just stays on zero, although the track plays fine and I can go forward or backward. I think it happens when I move too many tracks at once with the steering wheel controls. This is with a 7th gen ipod with lightning connector.
 

·
Registered
Joined
·
4,973 Posts
One more quirk: When using an iPod (either AAC or alac tracks) the elapsed time bar just stays on zero, although the track plays fine and I can go forward or backward. I think it happens when I move too many tracks at once with the steering wheel controls. This is with a 7th gen ipod with lightning connector.
Noticed this aswell. Happens if you switch songs too fast... ^^

Sent from my Samsung Galaxy 3 via Tapatalk.
 
481 - 500 of 1124 Posts
Top