[tspence73]

Hi all,

I am trying to design my next-gen upgrade for my super-sentra. My design goal is to have the best axis response possible throughout the frequency response range.

I was reviewing graphs and think I have a winning pair. First, I wanted the best midrange performer I could get that has at least a decent extention in flat response until the off-axis response starts crapping on it. Then I wanted a tweeter that could go low, real low and yet still have a very good extention before off-axis response is corrupted. Third, I wanted to keep the crossover point low enough to keep it out of the critical 2.5KHz - 6KHz range. Well, I think I have my combo.

The Scanspeak 12m 4.5 midrange:
http://www.tymphany.com/datasheet/printview.php?id=72

Please note that the off-axis response starts crapping out at around 2KHz. My plan is to eventually get a sound processor with a 48db/octave slope capability and use that to highpass this driver at 1.5KHz to help avoid the off-axis response problems above 2KHz.

Then we have the ADI (Tang Band) ceradome with an incredible response graph:
CeraDome Tweeter

You'll notice this tweeter can go low, real low. I plan to highpass this at 1.5KHz, again with the 48db/octave slope to avoid the rising distortion below this point as much as possible. Also, notice the off-axis response crapping out at 15KHz!!!! Wow. That's perfect.

With a proper A-pillar build, this should be a really nice combo that will give a really smooth response, even off-axis throughout the critical frequency ranges of 250Hz to 15KHz. That's some good chit mang.

What do you guys think of my plan?

 

[falkenbd]

Sometimes superb off-axis response can be detrimental. (Think reflections)

Why would you assume that your tweeter can play 2 khz better than your mid? Look at the rising THD of that tweeter when you go that low compared to the low THD of the mid at that point. If your mid and tweet are mounted together (properly) it should act like a point source and you won't need to cross that low)

Didn't you just get kicks made? (Why not use those)

I thought Infinity Reference were the best speakers ever made?

 

[tspence73]

The Infinity Refs were the best speakers I could find at retail stores. That doesn't mean I can't custom-build my own setup that sounds better.

I want to give this a try. If the a-pillar idea doesn't pan out, I can always go back to the kicks/Infinity Refs and re-sell the 12m.

This is a hobby and if I'm not striving for something new and better I might as well not bother thinking about car audio at all.

 

[Melodic Acoustic]

I would have to agree I would never play that tweeter that low, hell no tweeter. You will be miss out on part of what the 12m can do for you. Don't get me wrong the tweeters graph look great, but let it be a tweeter.

 

[[email protected]]

Great choice on the 12m, dont knwo anything about that tweet tho. Like stated I would run that mid up higher than 2k, get a godd EQ and you can wqork out any major kinks you find in its response after its in your car.

I am eyeing this new DLS tweeter out myself, its not coming out till next month tho
DLS - Products
they have a graph in the manula or product info page.

They also have an interesting mid that plays really flat up to about 16k on axis, in the same scandanavia line

I would imagine they will be alittle pricey but I dont think anymore than the scans

 

[falkenbd]

Tspizzle, I think if you are serious about trying this setup (It could be a good combination) you'd be best off getting yourself a measuring mic/pre amp combo for use with a PC and MEASURING the results instead of trying to guess what crossover points you'd use MONTHS before even purchasing the speakers.

This is getting back to "Why start the thread if you know what you are doing already"...

Yes, try those mids, and those tweets. Figure out what crossover points to use AFTER you have them installed. Because install will play a role in how well those speakers do at which frequencies.

 

[tspence73]

I would have to agree I would never play that tweeter that low, hell no tweeter. You will be miss out on part of what the 12m can do for you. Don't get me wrong the tweeters graph look great, but let it be a tweeter.

My thinking is to keep the drivers operating in the frequency range where axis dispersion is uniform and put steep xover points just before where there is major dispersion variance off-axis. My bet is this will give more listening positions a uniform quality and improve the chances that listening positions that aren't ideal (ie, a car at any seated location) will get good response.

I also want to keep the crossover point well below the critical frequency range of 2.5KHz - 6.5KHz. I find it very irritating that so many people think it's a good idea to transition from one driver to another in the most sensitive part of the range of hearing.

I figure this combo should give good results in conjunction with a great sound processor. I'm holding my breath for the MS-8 but probably shouldn't.

 

[falkenbd]

There are a lot of things you aren't considering. You are taking a few things that you have heard way beyond the useful context.

You can integrate 2 drivers so you won't be able to tell that its 2. In this situation crossing them at 4khz will work, But not likely with 48db/oct crossovers.

Just using 48db/oct crossovers on everything is probably not a good idea. You are taking something way beyond its useful context here.

You should read the 2 crossover threads that minivanman created.

To properly integrate 2 drivers, just picking a cool crossover point and using 48db/oct isn't going to work. Unless you believe it sooooo much that you ignore what you are hearing and assume its good.

 

[tspence73]

Tspizzle, I think if you are serious about trying this setup (It could be a good combination) you'd be best off getting yourself a measuring mic/pre amp combo for use with a PC and MEASURING the results instead of trying to guess what crossover points you'd use MONTHS before even purchasing the speakers.

This is getting back to "Why start the thread if you know what you are doing already"...

Yes, try those mids, and those tweets. Figure out what crossover points to use AFTER you have them installed. Because install will play a role in how well those speakers do at which frequencies.

Well, the off-axis drops are already done for me. It's a good guide to follow ahead of time IMO, unless there is some reason why I should doubt those graphs they provided.

 

[falkenbd]

Well, the off-axis drops are already done for me. It's a good guide to follow ahead of time IMO, unless there is some reason why I should doubt those graphs they provided.

I was saying get measuring equipment for in car response.

Reflections are killer.

So is a too small enclosure in the a-pillar.

You are trying to jump up a few notches in SQ here, this is good. But you don't get there by just buying expensive stuff. You need to figure out WHY certain things work and others don't. Not just think they will because someone else said it would.


Just a small example, using a 48db/oct crossover might actually cause a phase shift on a certain driver, and if 2 drivers both had a 90 degree phase shift they could be 180 degrees out of phase at the crossover point.

I swapped the phase on one of my subs last night and the response dropped to almost nothing at all. It was the coolest thing I've ever seen. Two subs moving around like they should be creating all the VBA in the world, and there was almost NO SOUND! Then swap the phase back, even on the same sound at the same volume, and poof the disappearing bass is back again.

 

[tspence73]

I was saying get measuring equipment for in car response.

Reflections are killer.

So is a too small enclosure in the a-pillar.

You are trying to jump up a few notches in SQ here, this is good. But you don't get there by just buying expensive stuff. You need to figure out WHY certain things work and others don't. Not just think they will because someone else said it would.


Just a small example, using a 48db/oct crossover might actually cause a phase shift on a certain driver, and if 2 drivers both had a 90 degree phase shift they could be 180 degrees out of phase at the crossover point.

I swapped the phase on one of my subs last night and the response dropped to almost nothing at all. It was the coolest thing I've ever seen. Two subs moving around like they should be creating all the VBA in the world, and there was almost NO SOUND! Then swap the phase back, even on the same sound at the same volume, and poof the disappearing bass is back again.

Aren't phase issues normally encountered more with passive xovers? I thought active processing was mostly immune to phase issues. Esp with a good processor that does the thinking for me.

 

[falkenbd]

Aren't phase issues normally encountered more with passive xovers? I thought active processing was mostly immune to phase issues. Esp with a good processor that does the thinking for me.

1st: active crossovers still effect phase,

2nd: what processor does the thinking for you? that isn't really the point of them at all...



the point I am trying to get across to you is, YOU HAVE TO DO THE THINKING.

If you want the new stuff you buy (NO MATTER THE PRICE) to work well, you will have to:
1. stop making assumptions
2. stop reading something and believing it verbatim
3. start trying to understand root causes (this ties into 1 &2)

I understand what you are trying to do, I think its good. You need to get past the old spence ways. Break out of spoon feed mode.


Here is something to read: Interference - Wikipedia, the free encyclopedia

 

[MiniVanMan]

Spence, stop trying to predict what slope you want to use for your setup.

There's a lot of study that's been done on how different slopes affect things like power response, and polar response.

If you have a tweeter that can truly handle 1.5khz, and a mid that can play cleanly to 5khz, on-axis, then you could use the mighty 6 db slope that gives the best polar and power response of all the slopes.

I'll reiterate what somebody else said about point sourcing. Keeping the mid and tweeter together, and on-axis is critical to a good point source that takes advantage of excellent polar and power response.

I'm sure you'd be happy with the 12M, but I'd look at something a bit cheaper to start with and maybe smaller so you can accommodate a mid and tweeter together up on your dash somehow.

Just a thought.

 

[FoxPro5]

With a proper A-pillar build, this should be a really nice combo that will give a really smooth response, even off-axis throughout the critical frequency ranges of 250Hz to 15KHz. That's some good chit mang.

Sounds real spiffy until you actually get done with the project and realize there's nothing you can do with such awful PLD's in that location. Good thing that driver is fairly forgiving and transparent otherwise I suspect you'll really not like trying not to hear your L MR all the time.

And it saddens the Fox to know you'd cut the most beautiful part of the 12m out and force it on a compact dome. Instead of boasting about a flat response to 1k, they should just be honest and say it sounds like flat out **** at 1k. But WTF do I know, I haven't even had my beets yet today..............

 

[falkenbd]

where is donvanM with the cat pictures when you need him...

just kidding...

I think spence is starting to think this one over... which is why he hasn't responded 10 times in the last hour

 

[tspence73]

I really don't want to do a xover point right in the middle of the most critical range. I would rather xover at 7KHz than between 2.5KHz & 6.5KHz.

What the hell is wrong with a steep slope? Someone show me some numbers on this hocus pocus you speak of. The good thing about a sound processor is that I can try any xover points I want and listen to them and decide. If you guys are right about a 6db/octave slope, I'm intrigued that it would work to great effect. I wouldn't bet on it thought but stranger things have been true in this hobby so far that I wouldn't have guessed ahead of time.

 

[MiniVanMan]

I really don't want to do a xover point right in the middle of the most critical range. I would rather xover at 7KHz than between 2.5KHz & 6.5KHz.

What the hell is wrong with a steep slope? Someone show me some numbers on this hocus pocus you speak of. The good thing about a sound processor is that I can try any xover points I want and listen to them and decide. If you guys are right about a 6db/octave slope, I'm intrigued that it would work to great effect. I wouldn't bet on it thought but stranger things have been true in this hobby so far that I wouldn't have guessed ahead of time.

Who said there's anything wrong with a steep slope?

Also, you are in NO position to call anything I say "hocus pocus". ESPECIALLY when you don't comprehend what I'm saying.

I said, don't get caught up in trying to determine slopes BEFORE you actually do the install.

There are definite drawbacks to a 48 db slope in a car. For one, you'd better have dead balls accurate distance and spacing between drivers. In other words, they need to be identical to get proper phasing with a 0, 12, 24, 36, or 48 db slope.

There's this misconception that steeper slopes are better. No, they're just steeper. In fact, there are many circumstances when odd order slopes are superior (6, 18, 30, etc), i.e. MTMs.

You also don't know what you're acoustic slope will be, and that has more of an effect than electrical slope.

 

[Dr.Telepathy SQ]

Who said there's anything wrong with a steep slope?

Also, you are in NO position to call anything I say "hocus pocus". ESPECIALLY when you don't comprehend what I'm saying.

I said, don't get caught up in trying to determine slopes BEFORE you actually do the install.

There are definite drawbacks to a 48 db slope in a car. For one, you'd better have dead balls accurate distance and spacing between drivers. In other words, they need to be identical to get proper phasing with a 0, 12, 24, 36, or 48 db slope.

There's this misconception that steeper slopes are better. No, they're just steeper. In fact, there are many circumstances when odd order slopes are superior (6, 18, 30, etc), i.e. MTMs.

You also don't know what you're acoustic slope will be, and that has more of an effect than electrical slope.

Steep Slope passive Xovers= great audio hype marketing

Think CDT Satnet. Ultra high slopes used in 2 way passives comp sets. I never understood that, given most people will end up having well over 6 inches of verticle distance between their midbass/tweeter installs per side.

Focal uses this thought process too.

 

[falkenbd]

I really don't want to do a xover point right in the middle of the most critical range. I would rather xover at 7KHz than between 2.5KHz & 6.5KHz.

What the hell is wrong with a steep slope? Someone show me some numbers on this hocus pocus you speak of. The good thing about a sound processor is that I can try any xover points I want and listen to them and decide. If you guys are right about a 6db/octave slope, I'm intrigued that it would work to great effect. I wouldn't bet on it thought but stranger things have been true in this hobby so far that I wouldn't have guessed ahead of time.

Do you like to learn or just be given a solution? Everyone in this thread has pretty much pointed out that choosing 48 db/oct before even getting the drivers is a bad idea. Same thing with chosing crossover points...

I understand what you are saying about trying to avoid crossing over in the range of 2.5 khz and 6.5 khz.

You need to do some reading about crossovers, that's the point I think everyone is trying to make.

The "Give me numbers" statement shows that you are unwilling to take the time and effort to understand what is going on.

Look for minivanman's threads on crossovers. Do an advanced search on "Crossover" [in title only] and user "minivanman" [exact matches only].

They'll get you started.

 

[rockinridgeline]

The frequency response on that tweeter doesn't look that appealing to me. Pretty jagged. Not the kind of tweeter that would typically be paired with that quality of midrange.

I second that thought on a-pillar for that mid. Not likely to be able to get the enclosure size you need. Keep thinking.