[JasonB]

I have a 2007 Toyota Matrix and currently have 2" Tang Band full range drivers in custom on axis sail panel pods and Dayton RS180's in the stock door locations. These are all run off of an older MTX 4 ch amp rated for about 70 watts/ch. The rest of the system consists of stock rears run off of the MS-8's built in amp and a Dayton 12" in a small sealed box powered by a JL Audio JX-1000. There is more info on my install here:

http://www.diymobileaudio.com/forum/build-logs-project-install-gallery/103485-2007-toyota-matrix-sq-budget.html

I have been struggling to get the midrange to sound right for a long time. Today I spent a few hours tweaking and listening. I learned a couple of disappointing things. First, a lot of the midrange harshness I am hearing is from reflections off the glass from my 2" Tang Bands. I had tried crossing them anywhere between 500hz and 1000 khz. Today I tried 3 khz just for kicks and the mids actually got quite a bit better, a lot of the harshness is gone. Second, I do get some slight clipping at higher volumes from the RS180's. I only notice it with the 2" and the sub turned off. The RS180's cross to the sub at 90 hz, the clipping definitely not over excursion, it is either the MS-8 or the amp. I forgot to try turning the amp gains down in order to exclude the amp and pinpoint it to the MS-8. I will try tomorrow.

I want to do something to fix the situation but don't want to put much more money in to the system right now. The 2" in the sail panels need to go, there is no easy way to control reflections there and I don't think they are ever going to sound quite right. Crossed at 3 khz they sound ok, but if I am crossing that high a conventional tweeter will sound even better. The RS180's are a great mid crossed low like I originally had them but again if I am crossing higher than there are better choices out there.

I am thinking I will probably end up with conventional tweeters in the sail panels and different mids in the doors. The tweeter should be the easy part. For a mid I need something that is no bigger than the RS180, at 3" deep they just barely fit with a lot of work. No less efficient that the RS180's and be able to cross as high as possible.

Any input is appreciated,

Jason

 

[fish]

Where is your budget at for some mids?

 

[JasonB]

Where is your budget at for some mids?

I would like to stay under $150 for the pair, and that would have to include shipping to Canada.

Before I bought the RS180's I had also considered the SB Acoustics SB17NRXC35-4. Nice driver but the QTS is pretty low (.32) for use in a door.

 

[Andy Wehmeyer]

Move the mids to the door and add a tweeter. No need to aim the mids or the midbass in this configuration.

 

[JasonB]

Move the mids to the door and add a tweeter. No need to aim the mids or the midbass in this configuration.

Andy, if I understand you right you are suggesting keeping the RS180's in the stock door locations, moving the 2" full range drivers also to the doors and adding tweeters to the sail panels?

I'd have to do quite a bit of cutting and fabrication to get the 2" mids in to the doors. I was hoping that I would be able to get away with 6 1/2" or 7" midbass in the stock door locations and tweeters in the sail panels.

The link below has a pic of the same door panel my car has. It's not the easiest place to mount extra drivers in and I was really hoping to avoid cutting in to the door panel.

How To: Subdue Door & Hatch Rattles - The Matrix Garage

Thanks,

Jason

 

[Patrick Bateman]

I have a 2007 Toyota Matrix and currently have 2" Tang Band full range drivers in custom on axis sail panel pods and Dayton RS180's in the stock door locations. These are all run off of an older MTX 4 ch amp rated for about 70 watts/ch. The rest of the system consists of stock rears run off of the MS-8's built in amp and a Dayton 12" in a small sealed box powered by a JL Audio JX-1000. There is more info on my install here:

http://www.diymobileaudio.com/forum/build-logs-project-install-gallery/103485-2007-toyota-matrix-sq-budget.html

I have been struggling to get the midrange to sound right for a long time. Today I spent a few hours tweaking and listening. I learned a couple of disappointing things. First, a lot of the midrange harshness I am hearing is from reflections off the glass from my 2" Tang Bands. I had tried crossing them anywhere between 500hz and 1000 khz. Today I tried 3 khz just for kicks and the mids actually got quite a bit better, a lot of the harshness is gone.

What makes you think that the midrange harshness is being caused by reflections off of the glass? Tangband 2" drivers have voice coils that are smaller than many tweeters, just 1/2" to 3/4". Due to the very small size, they distort quickly. If you look at the measurements done by John Krutke at zaphaudio.com, you'll see the distortion in his plots.

I've used them, and I'd wager that the harshness you are hearing is due to distortion, not due to where they're located. Possibly both, but 70 watts is a huge amount of power for those drivers. IIRC, most of them are rated for just ten watts.

Unfortunately, there's no easy solution. If I were using the TBs, I'd use them in an array where the power handling will be increased dramatically.

 

[JasonB]

What makes you think that the midrange harshness is being caused by reflections off of the glass? Tangband 2" drivers have voice coils that are smaller than many tweeters, just 1/2" to 3/4". Due to the very small size, they distort quickly. If you look at the measurements done by John Krutke at zaphaudio.com, you'll see the distortion in his plots.

I've used them, and I'd wager that the harshness you are hearing is due to distortion, not due to where they're located. Possibly both, but 70 watts is a huge amount of power for those drivers. IIRC, most of them are rated for just ten watts.

Unfortunately, there's no easy solution. If I were using the TBs, I'd use them in an array where the power handling will be increased dramatically.

I first noticed a lot of the harshness went away with the windows rolled down, I then tried surrounding the 2" full range drivers with a towel and this improved things dramatically. Also, the harshness is there at all volumes, not just when I turn it up.

I agree, 70 watts is lots of power for a 2" driver but crossing them over at 1 khz makes a big difference.

Jason

 

[req]

well putting the towels around the drivers is not necessarily a factor of amplitude to the driver, but diffraction and reflection properties of the installation.

think of it like this,

the point on the right is the speaker, and all the 'waves' coming from it is a sine wave, lets call it 1000hz. all the secondary ripples in the left and top left are diffraction and reflections off of surfaces around the speaker, or the rear wave of the speaker getting out there and mucking stuff up too.

basically, people have been trying to make enclosures with smooth round surfaces to combat diffraction on the edge of a surface

some images that should help;

by placing the towel back there, it helps kill extra energy radiated laterally\off axis that could cause diffraction and reflection problems... so thats why we stuff a towel back there to help testing different locations more easily.

thats why when you rolled down the windows it helped, because that energy that is reflecting off the side windows is 'released' and the reflection is gone. so properly aiming, or using dispersion lenses (horns, etc) to help control directivity is something all of us are interested in.

hope that helps.

 

[Patrick Bateman]

I first noticed a lot of the harshness went away with the windows rolled down, I then tried surrounding the 2" full range drivers with a towel and this improved things dramatically. Also, the harshness is there at all volumes, not just when I turn it up.

I agree, 70 watts is lots of power for a 2" driver but crossing them over at 1 khz makes a big difference.

Jason

Ah, then you're definitely hearing the sound of diffraction. Particularly since it's not level dependent.

 

[JasonB]

well putting the towels around the drivers is not necessarily a factor of amplitude to the driver, but diffraction and reflection properties of the installation.

think of it like this,

the point on the right is the speaker, and all the 'waves' coming from it is a sine wave, lets call it 1000hz. all the secondary ripples in the left and top left are diffraction and reflections off of surfaces around the speaker, or the rear wave of the speaker getting out there and mucking stuff up too.

basically, people have been trying to make enclosures with smooth round surfaces to combat diffraction on the edge of a surface

some images that should help;

by placing the towel back there, it helps kill extra energy radiated laterally\off axis that could cause diffraction and reflection problems... so thats why we stuff a towel back there to help testing different locations more easily.

thats why when you rolled down the windows it helped, because that energy that is reflecting off the side windows is 'released' and the reflection is gone. so properly aiming, or using dispersion lenses (horns, etc) to help control directivity is something all of us are interested in.

hope that helps.

Ok, if it is diffraction, and I agree that it is a possibility, can I use a shallow waveguide to help eliminate it? I could probably get away with a 1/2" deep waveguide with a 1/2" radius on the inside.

Jason