Part I: http://forums.corvetteforum.com/show....php?t=1997796
Part II: http://forums.corvetteforum.com/show....php?t=1998746
Part III: http://forums.corvetteforum.com/show....php?t=2002471
Part IV: http://forums.corvetteforum.com/show....php?t=2005028

I managed to get the new crossovers built yesterday. I used a couple Radio Shack hobby boxes to house the components. Since these are prototypes, and some tweaking is likely necessary, I used spring terminals to facilitate faster installation and removal later on. All the parts are from Madisound, including the drivers. To this point, the total cost is around $250. It took me about three hours to assemble the crossovers. Needless-to-say, I won’t be building too many of these, at least not without some process streamlining.

Here are the finished prototypes.





I got about twenty minutes of listening time after the installation. At first blush, they’re highly articulate without any of the nasty edge the Focal tweeters have. The improvement over the Focals was quite large in terms of smooth response, detail and listenability. Although the simulations show otherwise, it seems to me the tweeters need a couple dB of padding. This is probably a function of the interior of the C6. Remember, the initial measurements were gated to eliminate most reflections. Those reflections are the cause of the apparent brightness I noticed. Still, even a little bright, they sound very good. Classical, classic rock and especially jazz recordings are their strong suits. New rock, which tends to be oversaturated, distorted, compressed and generally harsh-sounding did not fare so well. These speakers are quite unforgiving of poorly-recorded material. I’ve found this to be true of every high-quality system I’ve ever heard. I’m going to leave the tweeters alone for now to allow Komoman the time to assess how much padding he thinks they need. It’s his car after all.

The simulations held up under these conditions which were less-than-ideal. The measurements and the program both proved their worth by providing a solid foundation for the crossover work which has as much effect on the sound as the drivers themselves. Without these tools, this would have taken months of trail-and-error work with countless hours of re-installation, building and listening time. Twelve years ago, my first attempt at building crossovers for a car took an entire summer. Not counting shipping times, this took about 5 days.

Comments or questions?

 

Awesome!

Mark

 

I have 2 questions.


1) What time do I get my car back tonight.

2) Where am I buying you dinner?

 

Thanks for the project.
What xover points and slopes are you using ?

 

Great job and all for $250! I guess the obvious questions, are you planning on posting crossover schematic/parts list? Will you be doing any in car measurements while fine tuning the response to komomans liking?

 

2000 Hz 12 dB electrical 24 dB Linkwitz-Riley acoustic slope. I haven't decided whether to publish specs or not.

This is where we get away from measurements and start listening, so no, the measurements are over for now unless there's a total re-do for whatever reason

 

awesome

 

I spent some time with them yesterday and today, though more today since I was in the car by myself and didn't have to worry about punishing a passenger's ears.

The speakers are amazingly detailed and clear, and Spkrboy's statement that they are unkind to modern rock is accurate. It's not that they don't sound good still, it's that you can hear how the mix has been deliberately distorted, my assumption being that the producers these days know most will be listening via those little white earphones that come with their iPods. So this is not a fault of the speakers, it's just that they're more revealing than that particular type of mix will tolerate.

We listened to quite a bit of Steely Dan and the jazz stuff sounds wonderful. Today on the way home I had Rush Retrospective 1981-1987 cranking and it really sounded great. You can hear every note of Geddy's bass riffs and Neil's drums pop & pound superbly. They are definitely suffering from some cabin gain with the windows closed up and it pushes them to the bright side. When I got off the highway and rolled down the windows it toned it down quite a bit, but I still think we're going to have to adjust the tweeter down another db or 2 maybe.

He warned me listening to a low-distortion setup would take some getting used to and he was right. However I went a long way towards getting accustomed to that on the drive home and I look very much forward to continuing that process. I think at this point the crossover point between the front speakers and the JL subs needs to be adjusted before I can make any sort of final conclusion. The crossover in the Xtant I'm running right now is at 80Hz and I think that's too high. I'm guessing pushing that down closer to 60 or maybe even 50 will be the ticket, those big 7" Seas should be carrying more of the load.

This will be addressed when the new Zapco Reference DC1000.4 I ordered from forum vendor Patrick at Pinnacle comes in and I can hook my laptop to it and start doing some SERIOUS tweaking. I'll report back after I start messing with that!

Thanks Rob!

 

"When I got off the highway and rolled down the windows it toned it down quite a bit"

I noticed the same thing on my system. Is that due to reflection on the side windows ?

"He warned me listening to a low-distortion setup would take some getting used to and he was right"

Can you elaborate ?
Thanks,

 

Yes, when you seal the cabin you get gain for the confined space, same concept as the volume of a subwoofer or any speaker enclosure. Where you get the gains varies from cabin-to-cabin, but given the position of the tweeters high in the doors in the C6, reflection off the windows makes a lot of sense.

The distortion thing is hard to describe until you've heard it. Distortion has a sound and most speakers system include it intentionally. Think of it like the intentional distortion that rock guitars use. It gives the guitar sound depth and texture that the strings straight up don't produce. All speaker systems introduce some form of distortion, including the one he's designed here, but it's much lower on these drivers and the crossover setup than is typical. So basically, it sounds like something is missing.. and it is, but it's something that wasn't supposed to be there in the fist place.

OK, I've tried to explain that to the point I know I spoke in circles.. hope there was something intelligible there!

 

I understand exactly what you mean about the distortion. I am experiencing the same thing.
Thanks for explaining.

 

Just in case.. there were 2 different topics there, cabin gain (why the tweeters sounded brighter) with the windows closed vs distortion. Cabin gain can certainly induce distortion, but that wasn't my point - I was talking about speaker systems in general vs what I have now.

 

Distortion in loudspeakers is a function of poor design or manufacture as opposed to deliberate intent. Drivers aren't built with a certain amount of distortion intentionally. Low-distortion drivers are few and far between, and the better ones tend to be more expensive, but there are exceptions like the ones we used here. There are also very expensive drivers that are terrible, too (Morel, Accuton).

Listening to a low-distortion is a different thing to get used to. It takes some time. Komoman's explanation about sounding like something is missing is dead-on. The important thing to remember is that once you become accustomed to a low-distortion system, it's hard to listen to a typical system because the distortion is easy to hear now, and like the Trinitron line on a computer monitor, once you notice it, it'll make you crazy.

There's more that could be said, but that's it in a nutshell.

 

I should have clarified, but I did know you were talking about speaker distortion.
It's kind of funny because I felt something was missing too, but I haven't been able to put my finger on it.
Now I know exactly what you're talking about.
Thanks for all the great info It's really helpful for someone like me who is trying to get educated on all this.

 

Your new Zapco Amp is rated at 4 x 150w.
Will that be driving the sub(s) also ?

 

Yes, the rear channels will be bridged to run the 2 8 ohm subs as a 4 ohm load.

 

Awesome project Spkr, and nice explanation of the process without getting too "techy"

As for the crossover point, asking a 7" to play from 50hz to what is effectively 1.8k is a tall order, and you will likely sacrifice some lower to middle midrange clarity doing it. I am sure you will do some serious measurements and listening before you decide, but most subs sound best in cars between 38hz and 45hz .. and 50hz is a lot to ask from a 7" cone with any power behind it.

IMO it is worth a listen to play around with the high pass point on the 7" without the tweets to see how different the midrange output becomes with various slopes and points. I spent a fair amount of time with my Focal polykev 7" in my vette doing just this and was really surprised how big a difference it made. I am likely going to change my 3 way to a 2 way with the tweet in this project, as the vette is more a race car than a cruiser these days

Enjoy the system Komo.

Fej

 

Komoman... did you get the new Zapco amp installed ?
We would really like to read your review of the new system.
Will that be Part VI ?

 

It's IN the car, but I didn't have a cable I needed last week. The cable arrived yesterday and as soon as I have time (no idea when that will be!) I will plug it in, hook it up to the laptop and start playing with the crossover point to the subs.

 

Slight progress last night, bumping this to keep the thread alive...

I pulled the door panels off to find out what was going on because midbass had disappeared. The explanation became obvious once I saw that the wires for the mid had gotten tanged up in the window mechanism. It's a tough balancing act in there between giving yourself slack to connect things and keeping it away from the window so it's an easy thing to have happen. But the good news is Sprkboy's new & improved way to get the door panels back on works like a charm.. I'll post that later in it's own thread for FAQ inclusion.

So now that I had midbass back it was time to get my laptop to communicate with the Zapco DC Reference 1000.4. The software is predictably quirky(small company where software isn't a specialty) and it took a bit to get it to work. My laptop had COM ports 3-14 marked as in use, I think from the Motorola driver software I had on it to charge my old cell phone. So after checking a tech doc included on the CD from Zapco I found out the port has to be number 1-9. OK, so into device manager and re-assigned to COM2. Well it still didn't to communicate, so guessing that maybe it just wouldn't be happy unless it had the first available number I moved it to COM1 and bingo, Zapco DPN loads and finds the amp, YAY! OK, boo.... I'm in restricted user mode which doesn't allow changes and when you go to administrator mode you need a password, which I don't have yet. OK, so message off to Pinnacle to get that. Patrick is a great guy and gave me an awesome price, just not experienced with Zapco so he's learning the ropes with me - a worthwhile tradeoff for the money saved.

So my listening experience last night is still without subs because I can't adjust the xover yet, but obviously vastly improved over what I had been hearing. The relative level of the tweet to the midbass needs to be adjusted. Spkrboy has a new coil for the xover that should give more output once we get it installed and we still may need to pad the tweet. He's of the opinion that there's a ton of cabin gain on the high frequencies and given the position of the tweeter mount that makes a great deal of sense. Some of it may be able to be adjusted via EQ built into the amp as well. What I am hearing though is still very smooth & sweet and I think will be absolutely killer when we nail the rest down.