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Most don't know me, my post count is quite low. I lurk and read and search a LOT. With just that I've learned SO much about audio, enjoying music, constructing systems, you name it. Today I put Dayton ND20FB-4's up temp mounted on the sails (pt cruiser) with a Nakamichi PA-102 crossed passive at 4khz. I also (reluctantly) put in a coil in series with my door speakers. There is a story coming.....(cue waviness and haze)

I've always done what most folks do, and that is replace the stock speakers with something that has a name on it. To that end, with the setup in my PT Cruiser, I bought Boston Acoustics SX65 for the doors (a 6.75" coax (actually originally it was the Pioneer ts-D161R. (REV). That was ruined by water intrusion. I was actually upset when I got the BA SX65s that a speaker labeled 6.75 was actually smaller in mounting diameter than the Pioneer REVs. Which gave me my first opportunity to build a spacer, the spacer actually did wonders for that mounting loc - It bridged a gap and allowed a much larger sealed front on the IB. )

For the dash I would use S35's. I went to work with my dremel and carved out a new home where there were only tweeters before. Sub I picked was the 10W3V3 and a prefab 1.0cuft box in the hatch. Picked up a Profile AP600, a Clarion APX2120, and a Nakamichi PA-200, and set out to install it all. I also had a Radio shack 7 band EQ I wanted mounted in the glovebox to play with.

I had a crossover (Audiocontrol EQX original). It crosses at 80hz, has a low (sub really), full range, and a hi output (above 80hz). So I put the sub on sub, the 6.5 on full range and I knew enough that I needed a highpass filter on the s35's. So I figured 400hz would do - got non-polarized generic caps of 82uf, and put in series.

It sounded good to me. Then I realized my bass was really boomy and I couldn't turn it up very loud without this weird distortion. It also didn't sound like any stereo I've heard. For a while I thought my stock system sounded better. Clearer for sure. I found out about RTA and the desire for a flat response. I never understood that before. Just thought you should play around with the EQ till it sounds good. Using a friends mic and my wifes laptop I found a LOT about my cars acoustics. It eats midbass, Highs get really weird, and I need a LOT less sub bass than I had dialed in.

Once that first RTA was sorta done I had my first epiphany and I think thats when I really got hooked on SQ. The music was so much clearer. I had to use a deep cuts up high around 6-8 khz, and 250 was like 9dB up. But OMG my system sounded SOOO much better with just a decent hack at setting levels and basic EQ.

But I still had this weird distortion or ringing, when I was playing music loud, and the music got "complicated". I listen mostly to metal, rock, classic, reggae, and on the harder metal tracks sometimes I had to just turn it down. It got tiring to listen to it. So I started to putz. It took me a while but I figured out that the speakers sound wasn't getting to my ear at the same time, and since I had more than one speaker doing the same thing, PLUS the phase shift due to the cap in the dash speakers.

So that got me started on looking at crossovers and I really wanted to just buy one but I couldn't find anything I could afford that did exactly what I wanted, and I wasn't quite ready (poor) to go to a really nice deck that does the active EQ inside. Plus I wanted it to do weird stuff, I'm ALWAYS messing with my system. Nothing fit, so I found out about car PC's. Most folks just run the audio OUT from it to the system. Eventually I figured out that I really wanted to use the computer as the EQ, xover, could to TA, effects, All sorts of neat stuff. Software existed that did exactly what I wanted and the cost to me could be basically free. I have tons of computer stuff around (I'm in IT), so a carPC should be cake. Well I'm still working on it. But the seed of an idea was formed.

I found the fix to my boomy rattly bass - I put in a 2nd order (12db) hi-pass filter at 100hz (282uf cap in series, and a 9mh cap in series (got real nervous cuz I figured it was a short on the speaker terminals), till I realized that at the frequencies it is a short at, the cap is also highly reactive (err higher reactance). It sort of serves to increase the effect of the cap by taking away signal from the speaker. Another epiphany! I know a bit of electronics, but this was a mind-screw. Wow that's how it works!!! Anyhoo getting the sub-bass out of my low range front speakers also helped me understand how my system could sound a lot better. The vocals cleared up! I couldn't believe it! My system sounded weird because the door speakers were running full range. The bass overpowered them and without the very low end - They sounded mighty fine!

I still had this ringing distortion when the music got busy. I thought it might just be some weird way my car is designed that its got a peak at that freq. I also kept hearing this ticking - quiet popping on the 6.5's. Troubleshooting led me to take out the tweeter (once I realized it was removable) - And OMG the ringing wasn't as bad! So I took em both out, but I still had that quiet "gasp" or whisper popping on those speakers. I had bought a Profile a1200xl and didn't use it, and during one of my putzing sessions I decided to have it run the door speakers. It sounded a bit better, but most importantly the ghostly whispering gasp was gone! I don't know what the deal is with that amp, maybe I'm just very good at hearing, but I could hear something odd with that Clarion in that whispery popping sound. My wife thought I was nuts, but the Profile amp sure didn't have it. So out it came for now.

Next I figured out headroom. I had the Nak set most of the way up to bring my front sound stage up. Another of my putzing sessions led to the removal of the Nakamichi - It was clipping and I didn't know that a sharp sibilance streaked sssss sound was so sorely unnecessary! On peaks the Nak was just hitting the limit. Wow, got that figured out too! I can really run a 75W amp to power a 30W speaker? Sure you can if you feed it 400hz and up and have the gain set right! It helps that the Profile is quite overrated. It made the ringing worse though. More output and all.

So today after reading for a while about harmonics and having realized that thats where the ringing distortion actually came from - I had ordered up a low pass to go with high pass on the door speakers, as well as the same for the dash, and a couple inexpensive sets of tweeters to play with. Really just picked at random, got a couple shapes that I thought I could work into my sailpanel or mount in the vent without trouble.

I put in the .8mh coil in series with the door speakers during lunch at work today. WOW! I finally fixed the ringing! Well its WAY down now. And I was able to prove to myself finally that each speaker needs to be basically alone in its frequency range.

(cue waviness and haze)

Back to the present. Well I'm very much sold on the CarPC idea now. I will want to mess with xover points and do TA so much that I don't think they sell something that I could ever afford to do it all. Very soon I'll be running a 4-way active system, with a 3 way front stage. Although I'll miss the nice caps. I spent a bit of money over the past few months on getting nice capacitors and that they all sound so different but they all sound a LOT better than any old non-polar.

So again, Thank you DIYMA for bringing me over to the dark side!
 

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Wow nice description of your trials and tribulations. I think this is how many of us get sucked into this hobby, first the speakers then an amp then the HU...then rip everything out and have a real go at it. :) Good luck with that next step of a carpc I want to eventually go that route too (I am also an IT person), but I'm not ready to commit to doing it in any of my current vehicles.

Again nice write up and I'm glad you're here learning with the rest of us!

P
 

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I'm with you on the learning from others aspect. This is a great forum for that and there seems to be less stupid flaming back and forth than on other CarAudio forums/ fora.

Nice description of your trials and experiences.
 
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