Passive Crossovers (split out of Ti800.4 review thread)

[smgreen20]

I'm to tired to reply w/what I need.

Mentioned above about the phasing. For every order the slope is, it's a 90 degree shift in the phase, so just switching +/- around isn't exactly the correct answer to the problem. It might help the response, but it wont fix the phase still. Now, will most of us hear a difference in the phase? Probably not, but I can on certain music.

Most people that choose to go active are willing to invest the money for the extra "items" needed. So any argument about more this and that can be thrown out of the window.

That said, sense sound is subjective, you should tune to your taste. Most going active probably have a adjustable xover that even has adjustable slope. My HU does all of that for me, a wide range of xover points and slopes 6, 12, 18, & 24dB/oct.

As noted above, impedance rise will effect the points of crossing over in a passive, you wont get that w/an active.

I'm done for the night.

[Eric D]

There are at least "two" downsides, and you forgot one of them...

Only maybe 1 out of 1,000 people in car audio have the required test equipment to setup an active crossover. And out of those people probably only 1 in 10 have the knowledge to do it right.

There is no way to get an active setup sounding better than a quality passive setup without at a minimum an RTA. You should also have an oscilloscope for good measure, as there is no point in fighting clipping related distortion while trying to get the crossover points correct. To really get it right you need to use a swept sine wave analyzer, and those run over $1,000 for a cheap one.

A possible third downside is what do you use for an active crossover? The ones built into the amp? What if they are 4th order and you need 2nd order? Or what if you only need 1st order? So now you have to buy an external crossover. Well, what if you need 1st on the mid, and 3rd on the tweeter? Are you going to run a passive on the mid, and go active on the tweeter with an external crossover because your amp is 4th order? This does not make any sense!

I'm sorry but I still disagree. I don't see where it's necessary to create a good active crossover without said equipment. BTW I have both an O scope and an RTA and I wouldn't use either when setting up an active filter. If you know the response curve for the particular drivers you are using and the fs especially for the tweeter, one can determine at the very least a good starting point for xover points. From there the points can be further adjusted if needed. I feel like you haven't completely read through my post. I did state that you would need enough adjustabliltiy to get it right. With todays processors, and even within some amplifiers it's amazing how much adjustability we have, and we can take advantage of that! Yes there are processors, not even extremely expensive, that can provide a multitude of crossover points AND slopes. Crossovers are by no means rocket science! Any company, including RF, can design a crossover with any goal in mind. As you stated before: RF was designing crossovers to sound good on a demo board. Well this is horrible if we install speakers in cars right??? Ok.. so forget that and let's say a company, like Boston, designed a crossover that has good off axis response. Fanstastic, but it's still not ideal. If the BA sounds great at 45 degrees then I would certainly say this is "better" than the RF philosophy, but what if I need to install my drivers at 30 degrees? You are inevitably going to have phase shifts especially within a vehicle and no design is going to be perfect (well the Utopia is close albeit extremely expensive ) Straight up.. with an active you don't have to worry about this. You can now work with the off axis response of just the driver/s. Sounds nice to me! You have only come back to shunt the active route,and that's fine, but you cannot deny the downsides I have provided about the passive xover. They do outway the negatives of going active. Look. I was never bashing on going passive. They are simple, cheap, and still sound good. I think I made that clear in my first post. I just want to share some knowledge. I think we are on the same page here yes? I'm a guy much like yourself. I like to experiment and run tests of my own. Not too mention just play around and try new things sometimes. I have done comparisons in the past with active vs passive. I can say that there was a particular time where I noticed a much more dynamic soundfeild when utilizing an active set-up compared to a "nice" passive design. I'm not going to sit here and say that everyone should junk their passive's. It's just not logical. At the same time I think it's silly (I'm not pointing fingers at anyone paricular here) when people when people trash an idea without trying and working at it first.

No, we are not on the same page.

A speaker's response plot from the manufacturer really means nothing of its in car response. So you have nothing to start with. If you do start with it you are heading in the wrong direction from the get go.

The processors and headunits with all the adjust-ability have TOO MUCH adjust-ability. They are far beyond what anyone can figure out or work with.

Crossovers are not rocket science, but they are very challenging to get right. I personally don't have the knowledge or experience to make a good passive crossover. Maybe if I spent an additional 2 years in school I would have what it takes to design one.

I mentioned RF doing it on axis, and Boston at 45deg, but those were examples of how they each do things. I am not advocating that 45deg is the sweet spot or anything, just that Boston obviously spent their efforts in a car, not a sound room.

You have not stated any actual downsides to the passive crossover. All of the points you made in this area can be disputed. How much power do they rob? It would have to be in the form of heat, correct? The only passives I have ever seen heat up were over driven. Don't take my word for it, test it. Measure the voltage at the amp, and at the speaker terminals. If the voltage is the same, where is all your power going, phase loss?

How can a passive make an amp clip sooner? By lowering the impedance beyond what the amp can handle maybe. In that case you need a better amp.

Any good passive is designed with the impedance CURVE of both drivers taken into account. Using the nominal impedance would get you so far off the map it is crazy.

All I can think at this point is we may be arguing from different angles. If you are building an IASCA SQ vehicle, then maybe I can see an active crossover being useful. However if you are any average user, or even an enthusiast, trying the active route will most likely result in discouragement.

[shawn k]

You naturally do not want to create a xover point that is above or below a drivers capabilities and the response curve will show you the best usable bandwidth in which a point could be chosen. I agree the impedance curve is certainly important, but if you don't look at a drivers response curve then how do you determine where to apply a xover point!!!??? You HAVE to look at the drivers response. You wouldn't high-pass a tweeter @ 50hz would you??

quote: "The processors and headunits with all the adjust-ability have TOO MUCH adjust-ability. They are far beyond what anyone can figure out or work with."

No sir! There may be some who lack the knowledge to use these properly, but your statement is quit derogative to those who CAN utilize these tools! To say that "They are far beyond what anyone can figure out or work with" is nonsense.

The downsides of passive xovers I had stated are factual. I'm confident with this subject, but I did a little research before I posted as I want to be factual and as accurate as I possibly can be. In FACT. Before I even posted my first response I did test the "power loss effect". I fired up the Ti elite 5's (excepted as a well designed xover yes?) I did the test with measuring the mid only like your previous test. I fed an amplifier with 100-400hz pink noise (far below the xover point) With ~10vac at the xover input terminal I read ~8.5vac at the mid output! A "loss" of ~1.5v, and yes the loss will be in the form of heat.

It's extremely difficult (at least for me) to explain how a passive xover can cause "earlier" clipping without some sort of diagram. Keep in mind that with this we are also comparing (at minimum) two channels of active and one channel of passive to drive two speakers. Maybe it's better to say that going active provides more "headroom" compared to passive with the same power applied to each system ie. 50w passive or 25wx2 active. I'm not sure at this point how to explain it any differently than what I did in my first post. Sorry

quote: " Any good passive is designed with the impedance CURVE of both drivers taken into account. Using the nominal impedance would get you so far off the map it is crazy."

Um..yea no argument there, I pretty much already stated that

I agree that "for the average user" passive is absolutely the way to go!! That's pretty much what I've been saying this whole time. As far as the "enthusiast", well I feel "discouragement", experimantation, and success is par for the coarse.

[shawn k]

Just something I found earlier. I wasn't originally going to post it but what the heck right?

I'm sure most of us have heard of the different passive xover designs: Butterworth and Linkwitz Riley are probably the most used/common. Well I found a Quote from Mr Linkwitz himself:

Crossover design expert Siegfried Linkwitz said of passive crossovers that "the only excuse for passive crossovers is their low cost. Their behavior changes with the signal level dependent dynamics of the drivers. They block the power amplifier from taking maximum control over the voice coil motion. They are a waste of time, if accuracy of reproduction is the goal."

[Eric D]

You naturally do not want to create a xover point that is above or below a drivers capabilities and the response curve will show you the best usable bandwidth in which a point could be chosen. I agree the impedance curve is certainly important, but if you don't look at a drivers response curve then how do you determine where to apply a xover point!!!??? You HAVE to look at the drivers response. You wouldn't high-pass a tweeter @ 50hz would you??

If I were making an active or passive setup, I would use swept sine wave testing to give me a frequency response curve of the driver, in its installation. That will give me insight to the off axis response, the frequency response of the driver itself, and the interaction of the vehicle on the driver. What you are mentioning is great for home speaker development, not car speaker development. And, I doubt an RTA would be accurate enough for good data in this case.

quote: "The processors and headunits with all the adjust-ability have TOO MUCH adjust-ability. They are far beyond what anyone can figure out or work with."

No sir! There may be some who lack the knowledge to use these properly, but your statement is quit derogative to those who CAN utilize these tools! To say that "They are far beyond what anyone can figure out or work with" is nonsense.

It is not so much about who can or can't use these tools, it is about who has the test equipment to EFFECTIVELY use these tools. With this level of adjustment at your fingertips, ears just won't cut it.

The downsides of passive xovers I had stated are factual. I'm confident with this subject, but I did a little research before I posted as I want to be factual and as accurate as I possibly can be. In FACT. Before I even posted my first response I did test the "power loss effect". I fired up the Ti elite 5's (excepted as a well designed xover yes?) I did the test with measuring the mid only like your previous test. I fed an amplifier with 100-400hz pink noise (far below the xover point) With ~10vac at the xover input terminal I read ~8.5vac at the mid output! A "loss" of ~1.5v, and yes the loss will be in the form of heat.

I give you credit for trying, I will say that. However, your specific test was invalid. You need to use a sine wave, not pink noise. Or better yet, use a swept sine wave to see exactly what is going on. The Ti crosssover is pretty complex, how can you be sure there is no equalization built into it which is affecting your results?

It's extremely difficult (at least for me) to explain how a passive xover can cause "earlier" clipping without some sort of diagram. Keep in mind that with this we are also comparing (at minimum) two channels of active and one channel of passive to drive two speakers. Maybe it's better to say that going active provides more "headroom" compared to passive with the same power applied to each system ie. 50w passive or 25wx2 active. I'm not sure at this point how to explain it any differently than what I did in my first post. Sorry

When you made the point of the high frequency riding on the low frequency wave, you were correct. It does not mean the amp will clip earlier so much as it means the input signal to the amp will clip more with a full range signal than with a signal which has been split up by an upstream active crossover.

I don't disagree with you on this point, but my related point is running a bridged setup with 4 times the power into the passive setup will be so much louder it negates the benefit of running the 4-channels active and separate.

You can make the argument that bridging results in four times the output distortion, but since that would still put it below the threshold where humans can detect distortion, I think this point is negligible.

Quick personal question for you, why are using the Ti crossover at all when you are advocating the use of active crossovers? I am not trying to be a dick, but I am reading into this as "do as I say, not as I do".

[Eric D]

Just something I found earlier. I wasn't originally going to post it but what the heck right?

I'm sure most of us have heard of the different passive xover designs: Butterworth and Linkwitz Riley are probably the most used/common. Well I found a Quote from Mr Linkwitz himself:

Crossover design expert Siegfried Linkwitz said of passive crossovers that "the only excuse for passive crossovers is their low cost. Their behavior changes with the signal level dependent dynamics of the drivers. They block the power amplifier from taking maximum control over the voice coil motion. They are a waste of time, if accuracy of reproduction is the goal."

Great quote by the way. However, I don't know if it really adds or detracts from your points. With all due respect to Mr. Linkwitz, he is after all German, and the Germans are known around the world as over engineering perfectionists, who are quite often as far from practical as you can get (Ever hear of the "Dora" gun?)

Let me quote Gary Church chief acoustic engineer for the Rockford Fosgate and Halfler divisions of Rockford Corporation at the point when Rockford purchased MB Quart and we started analyzing their products...

"The effort put into these German speakers is like measuring a sponge with a dial caliper"

[marko]

so how about x-overs that have a bi-amp capabality?



Devils advocate......

yep, i run mine bi-amped, 2x m50's bridged for midbass and m100 on mids/highs.

it's the most flexible passive i've ever seen, can change x-over frequency for midbass and also the bottom end of midrange, mid to top is fixed and should never need adjusting anyway as focal recomend the mid and tweeter as close as possible with this kinda set up.

the only other processing i use is a ax204a to split sub to midbass, no eq-ing or any other processor is used i could actually get away without using the 204 but i love the lpl capability

[smgreen20]

Eric, Shawn,

Have a read here. Not sure if this will help either side, but worth the read.

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

[shawn k]

Eric, Shawn,

Have a read here. Not sure if this will help either side, but worth the read.

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

Awsome man!! Good read! He pretty much reinforced everything I have been trying to say

[shawn k]

It is not so much about who can or can't use these tools, it is about who has the test equipment to EFFECTIVELY use these tools. With this level of adjustment at your fingertips, ears just won't cut it.

I disagree. Your ears are the "BEST" tools for something like this!

I give you credit for trying, I will say that. However, your specific test was invalid. You need to use a sine wave, not pink noise. Or better yet, use a swept sine wave to see exactly what is going on. The Ti crosssover is pretty complex, how can you be sure there is no equalization built into it which is affecting your results?

Invalid!? Nonsense! The test is legit! Why would you even think of testing something like this using a sinewave? I'm confident even if I used a sinewave I will have the same results. In fact I will try it today just to prove my point. The reason I used a limited badwidth pink-noise is due to the fact that it closely represents a "music" signal. We don't listen to sinewaves!!! Your power loss within the xover will be logarithmic. The more V in = a greater loss in power. I'm curious if when you did your test if you fed the xover input with enough V? At low V it would be hard to see any loss. Finally. I will do more testing today with other xovers and I'm confident I will gather similar results. The only eq'ing in a passive crossover would be possibly "a" notch filter to knock down a possibe peak in drivers response. I haven't opened up the ti xover (yet) but even if a notch filter exists, it alone would not results in a 1.5v loss in output. There's no way around it. Caps and inductors have resistance no matter how well they are designed.

When you made the point of the high frequency riding on the low frequency wave, you were correct. It does not mean the amp will clip earlier so much as it means the input signal to the amp will clip more with a full range signal than with a signal which has been split up by an upstream active crossover.

I'm not referring to the input signal at all here. If we have two seperate amplifiers.. one prducing low freq badwidth, and the other producing high freq bandwidth (freq split by an active xover), these two amplifiers will have more headroom compared to a single amplifer producing full badwidth with freq split by a passive xover. More badwidth = less chance of clipping.

Quick personal question for you, why are using the Ti crossover at all when you are advocating the use of active crossovers? I am not trying to be a dick, but I am reading into this as "do as I say, not as I do".

Again I feel like you have not been fully reading/comprehending my posts! I don't use the Ti xover. I was only using it on my test bench for this quick test. That being said, yes I still run a passive in my car for the a/d/s 3ways. Why you ask? Well maybe I cannot afford a processor with the adjustability I need. Maybe I cannot afford multiple channels of amplification nor have the room for it right now. Maybe I don't have the time to remove/redesign/reinstall my system. Maybe the car sounds really good and I just don't want to change it.......yet There are numerous reasons. After all. And I feel like a broken record here.. I never said one "shouldn't use a passive". Just because I'm not running active "right now" does not negate the fact of my points.

[marko]

I'm not referring to the input signal at all here. If we have two seperate amplifiers.. one prducing low freq badwidth, and the other producing high freq bandwidth (freq split by an active xover), these two amplifiers will have more headroom compared to a single amplifer producing full badwidth with freq split by a passive xover. More badwidth = less chance of clipping.

i guess it's all down to the quality of the amp and it's ability to produce the rated power throughout it's band width, a 200 watt per channel amp will still be a 200 watt per channel amp wether powering midbass or powering midbass and tweeters, it doesn't magically produce more power if it only has midbass to power

[smgreen20]

What comes to mind is the visual given in the basscube "secrets".

http://download.phoenixphorum.com/Manua ... ecrets.pdf
Page 8, figures 8 and 9.

Even thought the amp wont produce anymore power, the level of output from the speaker itself will be greater and possibly cleaner.

I'm having a hard time trying to convey what I'm getting at.




*edit* forgot the link.

[shawn k]

i guess it's all down to the quality of the amp and it's ability to produce the rated power throughout it's band width, a 200 watt per channel amp will still be a 200 watt per channel amp wether powering midbass or powering midbass and tweeters, it doesn't magically produce more power if it only has midbass to power

You are right. A 200w amp IS a 200w amp. But you are not comprehending what I mean by having more headroom. I never said that an amp will "magically produce more power if it only has midbass to power". I'm simply stating that any amplifier that only has to amplify a limited bandwidth (low freq or Mid freq or high freq) WILL have more "headroom" than the same amplifier playing "full" bandwidth. This is simple physics and it cannot not be denied.

[marko]

well then you just buy the next amp up with some of the money you saved on all those amps/processors

i do hear what your saying though but with a decent powerhouse of an amp headroom shouldn't be an issue..

[KUB3]

Tweeters will hardly draw much power anyway so in a sense it seems a bit of a waste of space having another separate amp just to drive them.

[shawn k]

Silly geese! The headroom will certainly be beneficial especially in the low freq area (like your midbass)! That being said, this is just "one" downside to running passive. "Collectively" the downsides far outway those of active if the ultimate in sound reproduction is of concern! So even if you do go with a larger amp you are still behind the 8ball!

[shawn k]

Tweeters will hardly draw much power anyway so in a sense it seems a bit of a waste of space having another separate amp just to drive them.

Have you ever tried it? True, high-freq drivers require less power for adequate results. However, imagine how smooth, natural, and dynamic your tweeters could sound if they were run with their own amplifier undisturbed of intermodulated distortion!

[ttocs]

so how about x-overs that have a bi-amp capabality?



Devils advocate......

Have you ever tried it? What results did you get?

From everything I know, the only real advantage to a bi-amp passive crossover is broader adjustment of the gain.

Say in your install your tweeter is 4 db too bright (as verified by an RTA). Your passive crossover has -3db, and -6db padding for the tweeter. Your crossover also has bi-amp ability. Since you can't get the exact -4db you need, you can run a pair of amps, leave the crossover set at 0db, and reduce the gain on the tweeter amp to get the exact -4db you need. But in all honesty, we are splitting hairs here. I don't think anyone will be hearing the 1db difference in this example.

I am bi-amping my diamond audio 3-ways in my stang and love it. I have the tweeter attenuation on the x-over but it gives me the 6.5 on one side to adjust, and the 4 - 1" on the other side of my 4 channel amp. I have yet to get the speakers to the point the sound bad with out having to put my fingers in my ears to hold the blood back. Gives PLENTY of headroom as well as tunabiliy, and I am even running my rear speakers off of the RAF of the x-over as well.

[ttocs]

I disagree. Your ears are the "BEST" tools for something like this!

aw hell, someone is gonna earn a nick-name and a title to match mine with quotes like that. What kind of crazy talk is this?

[shawn k]

Haha! I'm not sure how to accept that comment, but I stand by my saying I take it we share the same view???

[Eric D]

Shawn, I think you don't fully understand what you are talking about.

Please explain to me how you can quantify anything using your ears? Or how about duplicating results? Your ears can tell you something is wrong, but they won't help you fix it.

Please explain to me how you can measure pink noise with a DMM? I am really looking forward to your explanation on this one.

On the third point I agreed with you and you managed to still disagree with me. What gives? So you are saying an active crossover does not go before the input to the amp and goes on the output? That would be a passive, not an active.

When you ran your pink noise test on the Ti crossover, what speakers did you connect too it?

[Eric D]

Shawn, your argument is falling apart like a house of cards...

Please take a moment to study the photo I have attached.

You claim your ears are the best piece of test equipment for setting up an active crossover. How can you get repeatable and accurate results using your ears? I can run a plot 100 times and get the same data (+-0.5db) again and again.

You don't think sine waves are useful for plotting frequency response? How else do you do it other than an RTA with pink noise? If you think an RTA with pink noise is more accurate than swept sine waves, I really suggest you look into swept sine wave testing. It is as old as the hills and every speaker manufacturer relies on it.

All along you have been stating how passive crossovers "rob" your amplifier power. Look at the plot. Notice how at 100Hz, there is zero voltage loss. Notice how at 500Hz there is 1 db of voltage loss. This is not the crossover robbing power, it is the equalization built into this crossover to improve frequency response in the vehicle. Now look at 20kHz. Can you explain that to me? Even though the tweeter is padded by 4 db, there is actually a voltage GAIN of 2 db. Where is the power loss now?

How can you continue this argument without providing some measure of proof or evidence? A few posts up you mention "simple physics". Well if it is so simple, then why not explain it too us? You act as if you know something we don't, and are holding a carrot in front of us. You also went as far as to throw out a random term "intermodulated distortion". Do you know what that means? For starters it is actually "intermodulation" distortion. Although related to audio it has almost nothing to do with this discussion.

[shawn k]

Shawn, I think you don't fully understand what you are talking about.

No sir. I completely understand what I'm talking about. I'm feeling you do not understand me.

[qutoe]Please explain to me how you can quantify anything using your ears? Or how about duplicating results? Your ears can tell you something is wrong, but they won't help you fix it.[/quote]

You cannot quantify anything using your ears (except possibly how much one subjectively likes or dislikes the sound of something) I simply believe that when tuning a system, especially if one has experience, your hearing is as important, if not more important, than any measurement equipment used. I don't believe a deaf person who can read and understand the physics of using and RTA or Swept sinwave analyzer would be able to tune a system with satisfactory results. Our senses are a gift and we should trust them!

Please explain to me how you can measure pink noise with a DMM? I am really looking forward to your explanation on this one.

I never said you could!! Just where are you comming from with this? I'm assuming you are referring to the power loss test? I was simply reading the voltage drop after the passive xover. Again. You are trying to make an argument without even bringing the truth to the table. You are simply not reading my posts thouroughly or you are not coprehending them, In which case please at the very least know the facts of what I post before arguing. BTW I was not using a DMM for this test as a DMM has a hard time reading ac voltage especially with a reactive load! I was using an analogue meter!

On the third point I agreed with you and you managed to still disagree with me. What gives? So you are saying an active crossover does not go before the input to the amp and goes on the output? That would be a passive, not an active.

Yet again you are putting false words in my mouth Come on man. I think with all of the posts I have provided you should realize I know the difference between the two. It's only appropriate you show me the same respect as I do to you. For instance: With this whole debate, I have only tried to edjucate. Though I may argue some of your points, as you do mine, the difference is you are twisting and faslifying my statements which I have not done to you. Listen. You have brought up several points on your own that have contradicted your own statements yet I have not brought them to fruition out of respect! This is who I am. I believe it's feasible to have an arguement without falsifying or misconstruing statements.. do you?

When you ran your pink noise test on the Ti crossover, what speakers did you connect too it?

I started with the Ti 5 mid at roughly 5vac. This provided roughly a .5v drop. Then I substituted a 4ohm power resistor in place of the mid in order to reach a higher voltage without damaging the driver. (though I'm sure the driver would have handled this still)

[Eric D]

Shawn, you just completely ignored all the points I have made and used it as an opportunity to claim I am twisting what you have said.

When did this become "tuning a system"? I thought the discussion was active vs passive? You can't design either without ears AND test equipment. Ears alone won't work.

What do you mean you never said you could? You did it in a few posts up You stated you played pink noise and measured it with a DMM? You can't accurately measure pink noise with a DMM.

Lets run through this point one more time. An amplifier has an input and an output, correct? You put the RCA cables on the input, and the speakers on the output, right? So, if you run an active crossover, it needs to go before the amp, right? It would be on the input side of the amp. Your point before was that an amp would clip less with an active setup. I agree with you, but it is based on the input signal clipping less, not the output. The active crossover prior to the amplifiers will cut away midbass in the case of a tweeter, and the tweeter signal riding on the midbass signal will be able to feed into the tweeter amplifier's inputs with less clipping (more headroom).

Try your Ti test again with a sine wave. Play several different frequencies. Let us know the results.

[Eric D]

Shawn, since this is going no where fast, can we please try to see if we can find some common ground on something?

1) What is easier to install for the average person, the included passive crossover with a set of components, or creating your own active crossover?

2) What is louder, 4 100W channels running actively into a set of components, or 2 bridged 400W channels running passively into a set of components?

3) At what point do you feel someone has the ability to successfully install an active crossover setup? Entry level, first year installer, 10 years installation experience, some college, more?