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

[shawn k]

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

lol... no it isn't

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.

There you go (yet again!) putting faslified words into my mouth! It's got to stop sometime man! I never said using an RTA or other instruments are "not" usefull. I'm simply arguing that we shouldn't take the "human" element out of tuning!

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?

Sorry man but this graph is only representative of the response characteristics for the xover and is not adequate for our discussion. Why? Well the voltage applied to to these graphs is miniscule. Like I had previously stated: "Your power loss within the xover will be logarithmic. The more V in = a greater loss in power. At low V it would be hard to see any loss." The voltage applied here does not allow us to see a "significant voltage drop". For example: 1dBm=0.250vrms Voltage applied needs to be raised for a better interpretation.

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.

Look I'm not trying to be the "know it all guy", (I'm acutally a pretty humble guy) but if I can share some facts (not just opinions) I thought it was what forums were all about!? I'm not just going to walk away from a debate just because there are varying vues. I "can" and "will show results for some of the points I've tried to imply. However, I cannot "show" on a forum how a particular system sounds better going active vs passive!!!

I apologize that I wrote "intermodulated distortion". It was simply a product of thingking/typing fast. I know it's "intermodulation" distortion. I know what it means do you? It "is" a factor when considering xover design.

[csperl1]

Hmmmm still trying to decide if I want to ditch the 360 and go passive. Can anyone give me some input? KIDDING! Wow if I would have known it would have erupted into the battle of the egg heads I would have kept my pie hole shut! I am actually sorting through all the info and learning a ton. Thanks guys.

[Eric D]

Why? Well the voltage applied to to these graphs is miniscule.

Are you looking at the same graph as me? Where did you get any voltage information from that graph? You don't know what scaling factor was used.

[shawn k]

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.

You "STILL" are falsifying my statements! Man! Look.. you seem like a nice guy and all. Enthusiastic, like to help others, but you simply cannot argue/debate by twisting statements!!! (and you have on several occasions!) I DID NOT SAY I USED A DMM!!!

[Eric D]

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.

You "STILL" are falsifying my statements! Man! Look.. you seem like a nice guy and all. Enthusiastic, like to help others, but you simply cannot argue/debate by twisting statements!!! (and you have on several occasions!) I DID NOT SAY I USED A DMM!!!

I was simply reading the voltage drop after the passive xover.

[Eric D]

Ok you got me here. I re-read what you had posted. You are right, you did not state you used a DMM...

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.

You do state you measured a voltage drop from 10V to 8.5V. If you did not use a DMM, what did you use? I suppose you could have used an oscilloscope. Either way, does it really matter what you used, the point I got from it is you measured a voltage drop on pink noise. I don't understand how you can measure the voltage of pink noise when it bounces all over the place (by the definition of pink noise).

[shawn k]

OK. So we are all mature here and tho debates can be fun, sometimes there's a situation, like now, where arguments can go on forever.. and ever.. and ever... I've said what I believe is legitimate information only in hopes of trying to help. At this point I don't forsee a need to go on and on (which is probably what could happen lol) so I'm going to respectfully end my posts for this subject. If anyone would like more input on the matter I will gladly offer up my time and try my best to answer any questions (if any) via pm.

Although at some points it may have seemed like things were getting a little aggressive, I still had fun with this debate and no hard feelings by any means. I've never really been a part of the whole forum thing. Just browsed around here and there and I specifically chose to be a part of this "Phorum" because of you guys! You have a chill atmosphere here and I think that's terrific.

In the future: If I offer up information on any given subject please don't mistake me for a "know it all". I have made car audio my life for the past ~16 years and I have literally studied it. It was my profession for 12 years and would have been my career if the economy would have stayed on track. Through those years I have gained a welth of knowledge because I was open minded and I wasn't afraid to experiment. My only intention is to share some info and help others as I have been helped before. I'm not that guy at the competition who shunts eager to learn enthusiasts. If asked, I will show you my install AND any "secrets" up my sleeve ... I love car audio and I like to help others.. that's just me.

[Eric D]

I find myself re reading over all of this thread trying to figure out just what is going on. As most of us know, assumptions lead to trouble, and I think that is where I am going wrong here. Maybe Shawn will agree…

Example #1: Say Focal came out with a new set of components. They are top of the line in every way. They have a 6in mid, and a 1in tweeter. You can buy them two ways, one is with a Focal designed passive crossover. The other is with a Focal designed active crossover. I would buy the set with the active crossover.

Yes, you read that right. I would take the factory designed active over the passive, and I would have no bad feelings dumping the extra cash into the second set of amp channels needed to run it.

Example #2: Focal came out with that same set of components, but they did not offer an active crossover, only passive. Would I buy the set and use the passive, or would I ditch the passive and go active? I would use the passive.

I know without a doubt that I do not have the knowledge, experience, patience, and finances to setup my own DIY active crossover which will outperform the manufacturer's passive crossover. That line is important. I can make an active crossover which works, and probably sounds ok too, but it won't be better that what I started with in the box.

Now, here is one of those dreaded assumptions. When I make the above statements, I am assuming the following…

The factory passive is a good one in that is does not use undersized parts which will saturate and then distort the output signal.

***

Some more assumptions…

While I do think a car audio enthusiast has the ability to setup an active crossover which will work, I highly doubt it will outperform the included passive crossover. Anyone can feel free to disagree with me on this assumption, but doing so is like saying you know more about speaker design than the guys who designed the speakers. I personally don't fall into that category, so I know my design would not be better.

I assume the average person does not have a trained ear (or the test equipment) to setup an active crossover which will outperform the included one.

I assume the average person would like their system to be not only good sounding, but very loud if possible. For this reason I push the idea of four times the power on passives, over one quarter of the power on an active setup.

[Ahsmo]

There you go (yet again!) putting faslified words into my mouth! It's got to stop sometime man! I never said using an RTA or other instruments are "not" usefull. I'm simply arguing that we shouldn't take the "human" element out of tuning!

Is that human element measurable?

Are you talking about how an individuals have different frequency sensitivity curves?

I almost have lost enough hearing in my ears to collect disability when I get out of my current profession. So what sounds good to me is probably going to sound like dog shit to someone who hasn't been exposed to a significant amount of noise at around 4,000hz.

If that is what you are talking about, I don't want what sounds go to you because it is going to sound like shit to me. I want a flat frequency response curve to start with and an equalizer to make it sound good.