As many of you know, I've been yapping about developing a kick panel & component speaker combo for a long time. About a year ago I got started with my first prototype, and unfortunately it never moved after that because by the time it warmed up enough for me to work on it (unheated garage), we ran right into our home buying extravaganza, which kept me busy basically right up until now.

Well now we're in a new house, and I have a heated garage, so work is going to resume. With my prototype that I built, I had a very forward midrange, and also had harshness in the upper mid/low treble range. Because it was right around the crossover frequency, I wasn't really able to nail down the problem. Another bigger problem was that I didn't have adequate testing software at the time, so my abilities to tweak were severely limited.

Well now I have software, and I've figured out at least enough of it to get through the frequency response testing that I need for filter design. In addition, thanks to the old tweeters becoming discontinued, I've moved on to a different set of tweeters. These cost over twice as much, which will have an impact on final product pricing, but they are significantly better. This is a high end tweeter in every sense of the word, and is far better than what comes with any affordable component set that I've seen. The biggest benefit to these is that they play clean, even at low-ish frequencies. This means that there will be no harshness from the tweets, and I can also move the crossover frequency down farther, which will help avoid distortion issues with the woofer. I think these will be well worth the extra money.

For now I may try building another prototype filter by using the new tweeters in the existing kick panels, but ultimately I'm going to redesign the kick panels to better aim these tweeters. My current kick panel design was based on tweeters that sat in a swivel-cup, which made critical aiming of the enclosure unnecessary. These tweeters are a fixed-mount, so the tweeters fire basically at the center console instead of up toward the middle of the car.

I'm not giving any time estimates because I always take 5 times longer than I say I will, but at least I'm making progress. I hope that in the coming weeks I'll have a good sounding prototype using the current kick panels, and soon after that to have the new panels with the properly aimed tweeter.

I'll provide updates as I progress.

 

nice man i cant wait to see em

 

you tease!! I was hoping you were going to say they were ready.

 

That would have been a "major" update.

 

Sounds sweet Jim!

 

Last night I brought one of the kicks inside, set up a "mocked up" installation that placed the kick in a corner similar to how it sits in the car. I took measurements with the old tweeter, then I tried dropping in the new tweeter with the old crossover, and finally I measured the woofer and tweeter separately so that I can design a new filter.

I knew that I'd get a midrange bump in the midrange from the small enclosure, but what I didn't count on was having it be such a wide bump. What I saw in my plots was that overall, the output of the woofer over it's entire range was quite a bit higher than the tweeter. The system had a declining response from 1k right to 20k. The new tweeter is much more efficient, and even with the old filter, measured substantially better.

Listening was a very rewarding experience. While it's obvious that I've still got a long way to go on the filter, the sound was a substantial improvement with this new tweeter. All of that midrange harshness that I had is gone completely. The harshness that I had before apparently was 100% tweeter, and this new one eliminated it. Before it sounded a bit rough at low volumes, and got harsh at medium levels. High volume was flat out painful. When loud hurts your ears, that's a clear sign of distortion. With the new tweeters, I could get it very loud and the sound still remained completely clean with no hint of that distortion. These tweeters play so clean that I may try bringing the crossover down another couple hundred hz to see how they sound.

But, I still have a lot of filter development to do. Although almost everything I threw at it sounded very good, Hotel California sounded terrible, and there's no way I'm putting my name on a pair of speakers that can't do Hotel California.

 

Here's some interesting stuff to look at.


The first graph is the modeled response in black, with the woofer and tweeter responses shown in blue and red. Also in grey is an overlay of my actual measured response. You can see that they track fairly well, except around the 2khz range. This discrepancy is due mainly to phase differences between the measurements, and that's something that I'm trying to work out. Overall though, it shows that my simulations are at least in the ballpark. On all measurements, content below 200-250hz can be completely ignored. This type of gated response measurement technique does not allow for low frequency measurements without causing problems with the higher frequency accuracy.

Now, everybody's first reaction is "holy crap, that frequency response is terrible!" Welcome to car audio. The wild variations in the response is due mainly to cancellations due to the non-ideal baffle and the placement in the corner of my measurement room in an attempt to simulate the kick panel environment. I expect my in-car measurements to get even uglier.


The second pic shows the simulation with the same filter, but with the new tweeter instead of the old one. Right away you can see that the tweeter level is more in line with the woofer level, and doesn't exhibit the same amount of roll-off at the highest extreme. This really surprised me considering the extreme off-axis condition of the tweeter. Another thing you can see is that the response of both tweeters show the same dip at 3,200 hz, 5,200hz and 7,300hz. These are a result of cancellation due to reflections and can't be avoided. The large suck-out at 600hz is a bit more curious to me, and I haven't really determined the cause of it yet.

Fortunately, the human ear is not real good at hearing a dip in the response. However, the ear is extremely sensitive to peaks in the response, so those are what I am trying to avoid/eliminate. My main priority right now is to eliminate the broad bump centered at 1khz, and I also want to get better integration between the drivers around the crossover frequency. Once I accomplish that, I think that this speaker will sound very good.

 

You might fid that a lot of the issues disappear when installed in the car. I have had speakers that had a very eratic response out of car and in the car they smoothed out considerably. It was a MBQuart 3 way set I bought in 91. Just brought that up because I know what a pain in the butt it is to design a filter. Can't wait to see the kicks!

 

so jim you gonna sell any of these when there ready really interested to see what youve got

 

It depends on what you mean by "smooth out". Sound wise, this setup already sounds pretty good in the car. Measurement wise, on a low-resolution device such as an RTA, this system probably measures just fine already, but an RTA won't show the high Q dips that I'm getting. For that, you need a measurement system with much better resolution.

 

updates jim?

 

No.

Owning a house that's in dire need of updates is totally kicking my ***, and getting carted all over the North East to deal with my fiance's friends' weddings every weekend isn't helping. I've been so busy that I'm on week number 2 of an injector swap on my Corvette. That should be a 3 hour job.

I will say that I spent 3 days driving my IROC last week with the new tweeters in the car, and I'm actually quite happy with the sound. The woofer and tweeter seem to integrate well even though this crossover was designed around the old tweeter. It's clear that both the woofer and tweeter have very good sound. I don't think a lot of tweaking will be necessary to bring out the best that these drivers have to offer. The one hold up right now is that I want to build a new set of kicks to change the tweeter angle. My kicks were built based on using tweeters that sit in a swivel-cup and allow final adjustments, but these tweeters that I'm using don't have that, so I've got to make the adjustments right in the mold of the kick panel, which means I've got to redo every step... new plugs, new molds, new panels.

I'm dieing to get going on this though, and pretty soon I'm going to try to put off a few of my other projects so I can spend a couple weeks finishing this up and getting a few of them made for whoever may actually still want them.

 

are these the same ones from your site?

 

No. The kick panel itself is the same, but the pics on my site show kicks installed with customer's speakers. I'm building my own custom component set for the kick panels to be sold as a complete set.

 

aah i see still doing the ones on the site? i just ordered some jbl components.

 

Not at the moment, but after I fufill any potential orders for the full sets I'll be offering them again.

 

any updates are going to be available again. I will be needing a set here pretty soon.

 

Not really. I'm swamped with the house and other projects. Maybe fall.

However, I've been listening to the set in my IROC and I do really like it. Rather than major changes with the 2nd crossover, I think it will be minor. I need to contour the sound to restore the lower midrange "richness" that's lost due to the tiny enclosure size, and I need to re-aim the tweeters for more consistant high frequency imaging.

 

do you have any sets of the unloaded kicks to get rid of?

 

No, because even those have to be made specifically for the component speakers that the buyer is using, so I have to make them with the buyer's speakers in my posession.

 

so no time to do any? I am not in a big hurry and I can send you mine after I get them. yours seem to be the best I have seen so far. lmk If nothing else I can always wait. THX