35 replies to this topic

[Steve77]

Just wondering if the angle of the midbass speakers (in the case of 2 way splits) affects the tone or timbre of the sound?

The reason I ask is that my Alpine 6.5inch splits used to sound really good in my VL Calais, but in my last car (Lancer) and my current car (N15 Pulsar) they have a harsh sounding upper midrange.

The main differences between the Calais install and the more recent ones is that in the Calais the midbass speakers were installed on those prefab angled pods, whereas in the recent installs the midbass speakers were firing straight across the car. Could the lack of angle be the reason for the harshness?

[br85]

SQ Wannabe, on Jan 8 2010, 11:45 PM, said:

Just wondering if the angle of the midbass speakers (in the case of 2 way splits) affects the tone or timbre of the sound?

The reason I ask is that my Alpine 6.5inch splits used to sound really good in my VL Calais, but in my last car (Lancer) and my current car (N15 Pulsar) they have a harsh sounding upper midrange.

The main differences between the Calais install and the more recent ones is that in the Calais the midbass speakers were installed on those prefab angled pods, whereas in the recent installs the midbass speakers were firing straight across the car. Could the lack of angle be the reason for the harshness?

The angle WILL affect the upper midrange, and so will the actual baffle the driver is sitting on.

[Pulse-R]

also, if they fire straight across, you get a lot of cancellation around 600Hz.

[~thematt~]

As the other two mentioned, angling will impact midrange frequencies because they have a shorter wavelength. Angling will not impact midbass frequencies though, because they're too long.

[Cyberpunky]

Could also be reflection off inner door skin back at speaker, causing colouration and possibly intermodulation distortion. Fitting deflex panels plainchant etc or going to angled baffle may help.

peace

Cyberpunky

[Pulse-R]

I fought for a couple of years with midbass in the doors.

It really is the worst compromise of locations. The reason most people do it is for convenience, and no other reason.

[br85]

Cyberpunky, on Jan 9 2010, 06:01 PM, said:

Could also be reflection off inner door skin back at speaker, causing colouration and possibly intermodulation distortion. Fitting deflex panels plainchant etc or going to angled baffle may help.

peace

Cyberpunky

Do you really believe this Bruce? I am aware that deflex panels etc can make a difference, but ponder for a bit what is actually going on and you will likely conclude that this is not how it is. Lower frequencies = q loading, higher frequencies = no where near enough energy for the reflection to have any noticable effect on cone movement.

I think the reason plain chant and deflex actually have a noticeable effect is because they add mass and some damping to a resonant body.

[Cyberpunky]

I use deflex panels in the boxes of my 8s and subs, and could hear a marked improvement. My 8s are XO'd at 600Hz and in V shallow FG/MDF boxes, and had a similar resonance I have heard in many cars with door mounted mids, until I fitted the deflex panels to my boxes. One per box directly behind driver.

Internal reflections are, and always have been, an issue with Mids, just look at why a concert wedge is such a great design or B&W Nautilus speakers, Sonus Fabre etc. Do you think these designs are a theory or they work ? Ponder that for a while Jeff and let me know what theory it fails lol. They eliminate reflections back onto the driver. Have you ever seen a decent hifi speaker that is in a 3 inch thick box with the rear wall parallel to the speaker baffle, like a car door ? ever ?

So yes I believe that it is the panels design that helps disperse energy and prevent reflections back onto the driver and that it works. In my 8 boxes, the boxes were too solid for damping to have any significant effect IMO, so can only conclude that improvement was due to reducing reflections back onto the driver.

Cars are a poor environment for audio, we all know that, but its how you deal with the challenges that provides, that will dictate your results.

peace
Cyberpunky

[br85]

Cyberpunky, on Jan 9 2010, 11:43 PM, said:

I use deflex panels in the boxes of my 8s and subs, and could hear a marked improvement. My 8s are XO'd at 600Hz and in V shallow FG/MDF boxes, and had a similar resonance I have heard in many cars with door mounted mids, until I fitted the deflex panels to my boxes. One per box directly behind driver.

I don't doubt you had an improvement, however, the effect of the pressure on the cone either affects the q or nothing at all. I don't believe that the reason those pads improved your sound was because they somehow prevented backwave effecting cone movement.

Just because you found a solution, doesn't mean you correctly identified the problem...

[Pulse-R]

CP is right. rear-wave absorbers work.
even to reduce subwoofer harmonic re-radiation, they have a good effect.

Otherwise I wouldn't bother either.

but like anything in audio - you need the rest of the system to be at a high enough level to be able to hear the difference.

[~thematt~]

A couple of things. Those deflex panels work, but only on the higher frequencies. The order of 600-800Hz and above. They dont perform as they are marketed to (on midbass frequencies). The peak to valley is too small.

We've used the same principle these things are designed for, on anechoic chambers, and using deflex panels that are greater then 80 centimeters deep, could only get pattern dispersion to occur as low as ~200Hz. Any lower, and the peak-to-valley needs to be bigger (as well as the spacing between peaks for the air gap). Its kinda complicated, but kinda simple. Its determined (and I've been involved in the proof through proper experiments, if you're looking for that) from the distance between the peak and the valley (the air gap), being one quarter of the wavelength of the lowest frequency.

So you're deflex pads, in order to be midbass effective, need to be around 1 meter or more, thick, to 'disperse' (or interfere with the reflection of backwaves) for frequencies between 80 and 250Hz.

Plus, you have another problem. For lower midbass and all subbass, you dont HAVE a backwave in your enclosure. Its too small. Its a pressure zone, like the inside of a balloon. Wavelengths are too big for wave propagation. Movement in the cone causes the whole zone to change pressure, so there is nothing to 'disperse'.

I've put these in my midbass enclosures (a long time ago, to test if they worked), so I'm aware of the change in sound (very slight). Its not the same change (which is very audible, and distinguishable) as 'dispersing' a backwave. Its cause is simply down to putting a piece of rubber inside the enclosure. Like I said before, if you're operating a two way and you're frequencies go up to 600-800Hz, then yeh, they will start to work up top. But in a 3-way (crossed over 300Hz/down), the only thing you are 'cleaning' up is your harmonic distortions.

[Cyberpunky]

Jeff The OP is talking about midrange drivers even though he has referred to them as midbass, so we are talking about a midrange driver in a shallow cabinet. My Midbass drivers are XO'd @600 Hz @ 6dB and so are playing above 600 Hz and so not strictly a pure midbass(by Matts definition, I guess Dyn got it wrong *shrugs*). So my suggestion of using either angle or rear absorber may just work, in his situation, and may just explain why his speakers don't sound as good as they did in first car go figure. Real world, real advice, not just real skepticism.

Are you so stuck on theory that you ignore the issue the OP has in the real world? Could you even consider that just maybe my advice may in fact work in relation to the issue he faces. Do your theories fit with that ? Both Simon and I have won National championships by doing, and I'm pretty sure that their is no National title for having a theory on the net.

I couldn't fit my MTX black golds into my doors so I chucked them in a box and fitted them in front of my seats...whattayaknow I invented floor pods by accident and it worked. No one had done this before I did it. No one showed me this, No one told me it would work, no one had a theory. You guys can probably tell me why they work or shouldn't. with some theory or other, but I just did it.

Theory is fine and yeah, maybe you can create a perfect system in theory but at the end of the day, I created an OK sounding system based on experience and working within the limitations of my vehicle. Your theories may hold more weight if executed.

Theory would stop you guys fitting an 8 on the floor in a shallow undersized box, and having speakers in the kicks, and yet I did it with OK results. A wise man suggested if it measures bad but sounds good your just measuring the wrong thing. So is it ok to get the right result with wrong solution ? in theory of course lol

Can you please just build your ambiophonic dual mono array speaker car and show us how all this theory works at nationals already, instead of just telling everyone why we don't know what we don't know or otherwise get it all wrong all the time. Jeff I like that you don't take the status quo for granted but your incessant challenging of everything, can get tiresome when you always express things so black and white and won't consider that just maybe you don't know it all yet. There are those who talk, those who do, and those who do and talk. Which one are you ?
peace
Cyberpunky

Edited by Cyberpunky, 10 January 2010 - 11:15 AM.

[zion187reigneth]

post='1134933, on Jan 9 2010, 12:45 AM, said:

Just wondering if the angle of the midbass speakers (in the case of 2 way splits) affects the tone or timbre of the sound?

The reason I ask is that my Alpine 6.5inch splits used to sound really good in my VL Calais, but in my last car (Lancer) and my current car (N15 Pulsar) they have a harsh sounding upper midrange.

The main differences between the Calais install and the more recent ones is that in the Calais the midbass speakers were installed on those prefab angled pods, whereas in the recent installs the midbass speakers were firing straight across the car. Could the lack of angle be the reason for the harshness?

What i would do is make up a few of these . http://www.mobileelectronics.com.au/forums...showtopic=73107

Keep adding them onto your speaker mount and angling your speakers towards you until you get the desired effect.The desired effect will depend on what Freq range you are using in your woofer aswell.

You know you have given them to much angle when your driver side speaker takes over the sound stage .In that case you have come to a good understanding as you now know what angle is excess for your install.

Mounting must be secure so you dont add resonance to your test angles.

ehhhh i didnt even answer your question.

Edited by zion187reigneth, 10 January 2010 - 02:21 PM.

[~thematt~]

Cyberpunky, on Jan 10 2010, 09:13 AM, said:

My Midbass drivers are XO'd @600 Hz @ 6dB and so are playing above 600 Hz and so not strictly a pure midbass(by Matts definition, I guess Dyn got it wrong *shrugs*).

You and I both know I was referring to midbass frequencies. Not drivers.

What you get to play those frequencies is entirely up to you!!

I'm a big proponent of NOT putting midbasses in the doors. I've done more work then anyone else I know to get mine in there, and they quite simply DO NOT WORK!!

[Cyberpunky]

All Good Matt

AS the OP is asking about midbass but actually only has midrange speakers, can we actually forget all this midbass discussion as its not relevant. I have always been a big fan of using angle mounts as it helps on sooo many issues. The angle helps avoid reflections both from inside the door back at the driver as well as from speaker on other side, that may result in null points(cancellation) and peaks. It also allows you to get speakers more on axis, which often improves response to the listener.

If angle mounting is out, then deflex or plainchant may help IMO

peace
Cyberpunky