Well the subject line says it all.

I'm looking for input, people's personal experience, about digital or analogue delay devices.

For example, would time aligning a tweeter(with respect to the midrange)crossed over at 3khz be just as criticle as when it's crossed over at 6khz?

For those with the practical knowledge, which drivers do you get the most improvement on by using time alignment? Bass, midbass, midrange, tweeter?

Don't get silly with me Chadxton.

Adam

 

Hey Adam, these issues have been in my thoughts lately as well.

My intent is to run the 4 inch Poly Kev mid from about 250-300 up to around 5500-6000 and have the tweeter pick up from there as the most critical frequncies for pathlenghts seem to be in the midrange. (I'm using the Ligne Mistral TN-46 tweet, IMHO superior to the titanium tweets you are familiar with. This one has an inverted fiberglass dome http://www.focal-jmlab.fr/gb/car/arc...ages/165ex.jpg ). Beyond 6000 Hz it's mainly spatial info and this appears to be the way a lot of guys are now setting up their three way front stages, and experimenting with the placement of the tweets in the A-pillars, just below ear level, aimed following the curvature of the windshield, or somewhere in the kicks.

I'm torn as to where the midbasses should go.

If I put them in the doors the pathlenghts are not ideal but bass extention will be very good as the driver will see the door cavity as an IB.

If I put them under the dash as far back as possible the pathlenghts will be most ideal but it will be difficult to create enough space behind the midbass have it play nice and low.

As far as your question on time allignment, I should have some interesting observations soon, I'm just about to hook up the PXA-H700.

I have played around with time allignment but only 6 channels of it, my opinion being this: Every frequency is affected, including bass. Having a really well sorted out midbass to subbass transition has a lot to do with how well they are frequency and phase(time-allignment) matched. Seamless sound is hard to achieve, but boy does it ever sound good when this critical transition is spot on.

 

Here's an interesting thread somewhat on topic about mid to tweet x-over points and imaging:

http://www.carsound.com/UBB/ultimate...c;f=5;t=001568

And Phasing:

http://www.carsound.com/UBB/ultimate...c;f=5;t=001458

Pathlenght & X-Over freq:

http://www.carsound.com/UBB/ultimate...c;f=5;t=001558

 

Thanks Islandphile [img]graemlins/thumb.gif[/img]

I've read those threads before, but I always pick up something new when I read them.

Boy Mark really opened up a can of worms!

I'm very interested in how you set up your system, as our equipment is pretty similar.

Are you going to use more VRx amps on the front stage?

I was thinking of a VRx2.150 on the tweeters, VRx2.250 on the midranges, and a VRx2.400 on the midbasses myself. Currently my VRx2.400 rocks though. [img]smile.gif[/img]

I mounted my midbasses in the door, and let me warn you, they shake the hell out of it. You better have your door WELL dampened if you are going to mount the basket directly coupled to the door frame. I've got a ton of Cascade Audio Engineering VB2HD on the door frame, and 2 cans of VB1-S on each door skin. Also, I've got a few meters of weather stripping on the door skin for every surface that comes in contact with the door frame.

With over 250 watts on tap, as you know, that 6.5" midbass can move some air!

Later,

Adam

 

Here's an overview of what I'm trying to do. Read the one on bi-amping as well.

http://sound.westhost.com/biamp-vs-passive.htm

I want to try this with a twist. As most amplifiers have crosstalk between the stereo channels I am going to try using one amp for the left mid + tweet and another for the right channel mid + tweet. Dual gains really come in handy here.. and active processing naturally.

As far as which amps where...The VRx2.400 on the midbasses in stereo, Wavelength amp on right mid + tweet (not bridged), separate amp for left channel. I have enough amps that I could try run one amp on each midrange alone, and use a separate amp for the tweets....I see some experimentation coming up. [img]graemlins/thumb.gif[/img]

 

All frequencies are phase sensitive. Wire the mids/tweets out of phase and enjoy the odd soundstage (or correct it). Connect the mid-bass out of phase and the entire warmth and body of the music will change. Connect the woofers out of phase and enjoy the cancellation nodes

 

^^^I don't see any enjoyment in the above [img]graemlins/freak.gif[/img]

 

In a funny world, you don’t need any T&A. But all real men need some T&A.

You can TA left/right or you can TA tweeter to mid to midbass on the same side. And every car is different and with every position it’s different. The best setup I think has the least amount of drivers. The next best thing like say in a three way setup, would be to have one driver covering the majority of the frequency range, say like the mid ranging from as low as it can go without sounding like crap to as high as it can go with sounding like crap. And then fill in the missing lower and higher ends. So then I would say you want to tune in those mids and then work the surrounding drivers in to match those mids. And you have to also remember that EQ-ing usually messes up your TA-ing. So to dial it all in, you have to go round and round in a circle …………… which either brings sonic bliss or insanity.

 

Tom
That is the best argument for TA I have heard and I would now consider doing it if my setup required it. In a car the drivers are physically located all over the place (and not in a nice neat time aligned cabinet in a rectangular room as in home stuff). Phase angles, reflections, cancellations are all over the place in a car. The point of TA is to get the phase and timing correct at the driver (passenger) seat. Drivers wired in phase can actually be out of phase if your head is not located equidistant from each driver (correct me if I am wrong) so delaying a signal should theoretically put the system back in phase. Also, time shifting divers could help to overcome drivers located *****-nilly (technical term there) in your doors, floorboard, dash and a-pillars.

I have mentioned how I dislike EQ’s, and my justification is my system sounds ‘dirty’ or the music sounds damaged with the EQ in the loop. One of your points is that some of that is due to TA and this makes sense … maybe with TA I could use an EQ. EQ probably selectively shifts phase as well as frequency response…. Hmmmm sounds expensive and time consuming.

 

Regardless of how we align the waveforms, they are still going to arrive at our ears at differnt times if the sources are different distances away.

I think that the human ear is most sensitive to arrival time in the area that human speach covers. It's how we, as animals, are able to judge the distances of threats if we can't see them. That happens to be the "midrange" frequencies, so it totatally makes sense that pathlengths are so important in this area.

Aligning the waveforms will help with cancellation issues which will ultimately manifest itself in frequency response. So I understand how we can "go in circles" tuning time then frequency with an RTA or our ears.

What I'd like to consider, is how we percieve the results based on theory. In other words, how can Gary Biggs or Scott Buwalda rationalize the sound in their systems.

Keeps me head scratching...

Adam

P.S. Great posts above guys [img]graemlins/thumb.gif[/img]