how to make high/lowpass filter in series connection???

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Hello all!

I'm planning to build a 3 way loudspeaker system and is wondering how to make the passive crossover in a system wired in series(2 woofers) and parallel(the tweeter).

I am planning on using two 6.5" woofers and a tweeter (all 8 ohms) crossed @ 300 hz and 5000 hz...

If I wired all the transducers in parallel, the overall impedance would be 2.67 ohms... which is too low for my amp. So the alternative is to wire the two woofers in series and the tweeter in parallel relative to the woofers, which would have a total impedance of 5.33 ohms, which is acceptable...

But then, In a parallel connection, each woofer/driver/tweeter has its own set of +/- wires to connect the filter components to, while in the series connection, both woofers only have one +/- wire to share with....

So I was wondering how to make the low/high/bandpass filter for the 2 woofers in series...

And I was wondering what Zobels are used for and should I use them????

Thanks for any info...
It's a little unclear how you're laying all this out.
You're saying that it's a three way, but with two woofers and a tweeter. That's a two way system. A speaker is described as two way or three way (or four, or whatever) based on how many ways the crossover divides the frequency spectrum, not how many drivers are used.
Later, you say that you'd like to use crossover points at 300hZ & 5kHz. That describes a proper three way, but you've still only mentioned 6.5" woofers and a tweeter. If you try to run a 6.5" driver up to 5kHz, you'll have to listen with your head in a vise, as it will beam pretty badly. A 5kHz signal has a wavelength of something like 2.75", which coming from a 6.5" driver would be the sonic equivalent of a laser beam. (Proper dispersion of frequencies from a driver is a function of the wavelength you're trying to reproduce, vs. the size of the driver.)
What are you planning to use for a midrange?

One of the most important things you can do is ignore the advise of the "Audio Elder" that says if you try to cross a 6.5" driver at 5KHz you'll need to listen with your head in a vise. Laser beam my foot.

I love being a critic. I think I'll stick around the DIY audio forum looking for and reporting errors.

I joined the forum some weeks ago and am amazed at some of the ******** I've read.
Just out of curiosity, have you ever tried using a driver that size for a frequency that high? 2kHz, sure. 3kHz maybe. 5kHz? Go ahead...try it.
Ever seen something called a polar diagram? It's a plot of dispersion of a driver at various frequencies. The main variable is the ratio of frequency to the driver diameter/width. On axis radiation is always strongest, but off axis radiation drops off rapidly with frequency. In the vernacular, that's called beaming. It means that you've got to sit in one place to hear the higher frequencies...move to one side, and the high frequencies drop off; the sound goes dead.
Electrostatic speakers have a justly deserved reputation for beaming. Why? Because the panel width is wider than the frequencies being recreated. Acoustat had a single panel wide model (the 1+1? I forget), but it beamed above about 2 or 3kHz. Ditto for the Stax F-81 (one of the best sounding electrostats ever made, but it took a 200W amp to make it even whisper).
Setting aside questions of dispersion (the math is trivial), there's also the mass to contend with--in other words, the transient response would be somewhat less than wonderful by the time you got up towards 4 or 5kHz.


P.S.: The whole Neophyte/Prophet/Elder/whatever thing isn't my doing. If you've got a problem with it, take it to Jason. It's his site. He did the coding.
With a wavelength of 2.75" and a listening distance of 96" your head would have to shift laterally by about 16" before you would be at the center of the first cancellation null. This is nowhere near a situation that would require clamping ones head in a vise.

Additionally, the null wouldn't really be a null. The reduction in output would be on the order of 20-25db.

A two way system which takes advantage of the mechanical roll-off of the woofer, omitting the low pass filter AND which properly integrates a tweeter will, for serious listening from your favorite seat, impose little or no penalty when the head is shifted from side to side by a reasonable amount.

None of this is helping limking with his speaker project and GRollins and I might best continue this thread as a new one. All I'm saying is that the situation is not nearly as dire as GRollins suggests. I have constructed systems which take advantage of the mechanical roll off of midranges and when done correctly they are very nice indeed.

limking, buy yourself a copy of the "Loudspeaker Design Cookbook". Read it and understand it. You will then be ready to get started. You will also save a great deal of time.
With a 20-25dB drop at 16", what do you get at, say, 4-6"? 6dB, perhaps? That's a quarter as loud. I don't know about you, but I regard -6dB as pretty significant; to be avoided if at all possible. And 4-6" is pretty limiting, as far as seating arrangements. What if another person wants to listen? Their head will be 16" away, minimum, even if they're sitting shoulder-to-shoulder with the person in the sweet spot. You've just condemned them to a serious hole on the lower side of the 5kHz crossover point.
And there's still the mass to contend with. There's a *reason* that dedicated midranges are smaller and lighter than 6.5"
Now, you and I are in agreement as far as the mechanical rolloff trick...when it can be arranged. It takes a well behaved driver to get away with it--and we don't know what limking has on hand--but it's an elegant solution if the driver is up to it.

Hmmm. A 2 person, serious, listening session. That's a new one on me.

40 years in audio as an enthusiast and moderate to high end retailer and it's never happened. Am I missing something here?

Anyway, if these 2 listeners are not passionately in love there will probably be 36"+ between them. Even if the sweet spot was wide enough for both, what about the room; you know - standing waves and boundary reflections? An out of phase reflection can create a serious null too.

One room, one best spot. That's why people labor over speaker placement. If you want to give your guest a treat, you're supposed to give him/her your seat. You can then sit on the sidelines agonizing about room modes.

And the hits just keep on coming.
Life sure must be different on the other coast, as people over here frequently have guests. I've got a buddy who regularly hosts Friday and/or Saturday night sessions with as many as four or five other people in addition to himself and his room mate. His sweet spot isn't a spot--it's about three or four feet wide. Two people easily, three if they're friendly. (His listening seat is a nice sofa, so people can scoot back and forth as the occasion demands.) The image is stable, and the frequency response stays balanced. It works.
There used to be an audio club here locally. They met once a month at each others' houses. Some systems were pretty tight, others were wider. I didn't attend often, as I wasn't an official member of the club, but I never saw less than eight or ten people at one of their meetings.
There were four people the day I visited the fellow with the Genesis 1.1s. The listening spot there was easily two people wide, and I felt that the system might be capable of more (in many ways) once it was tuned in some more.
My system is similar. I don't have guests often, as my schedule doesn't match well with others. Still, when I get a new piece of equipment bought/built, I have people over.
In my view, anyone who's putting up with less should at least be aware that it's possible.
So...yeah, you're missing something.

You're describing a social situation.

OK, so the difference is in our definition of "serious."

Here's serious to me.

A very well loved piece of music.

Sitting comfortable in THE chair.

The room is black - not dark but BLACK. Not even an LED showing. No visual distractions. No unwanted photons bouncing around.

Zero aural distractions. No talking, shuffling, throat clearing, mechanical noises or breathing. No air conditioning, heaters or refrigerators cranking away. No ice melting in a glass. The phone is unplugged and the neighbors have been warned.

Not an object in the room vibrates, rattles or otherwise responds to the sound of the music; except the speakers of course.

Attention to the music is rapt, almost trance like; a transportation into the very heart of the matter.

But, then, I like to party too.
Who said anything about parties?
With the exception of the audio club, where food was served, and people frequently talked, all of the above meet your critera, with the exception of light. The fellow who has the regular Friday/Saturday night thing turns out the lights and has electrical tape over the LEDs. In all other cases, the room was light. My buddy and I tease each other about light and whether it matters, but other than that, everything is square.
Maybe people over here just know how to listen to music without dancing.
Besides, even if I'm alone, I regard it as an imposition on the part of a system if I've got to sit on a dime to hear the music. The system should be able to provide a decent image and balance such that you're not required to get out a measuring tape to make sure you're in the sweet spot.

As an observing bystander, maybe I can help sort this out. Or add fuel to the flames...
Bill is saying that music can only really be truly enjoyed under the perfect sort of conditions he describes, and if anything is out of place then why bother with trying to get fidelity for everyone.
Grey is saying that smaller drivers have better dispersion at high frequencies, so if you want to achieve good results over a reasonable area use a smaller driver for the high frequencies.
I don't see a conflict here. Different expectations, different solutions. This is the stuff that makes us human.
Fuel to the flames, probably. Someone is going to land on me for this one.

Music comes from the heart and mind of the performer/composer. It's intent is self gratification. Bach wrote for himself, not others. Paul Desmond plays for himself, not others. And so it goes.

That we can appreciate the efforts of musicians and artists is both psychological and physiological. The thread that links the listener to the feelings of the artist is a fragile and easily broken thing. Yet, it's attraction is strong; a "weak thread/strong thread" if you will.

The more complex and delicate the artistic offering the greater the need for accuracy in the transmission of the information to the listener.

The point in listening, presumeably, is to go directly into the mind of the artist, to understand exactly what he is doing and, if we're lucky, why he is doing it.

There is nothing that stands in between the mind of the artist and his own mind because the are the same thing. He gets it. It's point A to point A, the perfect straight wire and no gain needed.

Anything and everything that stands in the way of the artist and the listener reduces the meaning/quality/fidelity of it. This process is aural with some tactile ammendments.

All our senses compete for processing "slices" of our mind. Call it multi-plexing if you will. Multi-plexing reduces the ability to focus accurately on a single input.

It's obvious, to me a least, that if we reduce or eliminate the input to our other senses, we can increase the "fidelity" of aural perception.

So, I say, get rid of new or strong aromas, get rid of light, get rid of noise, get rid of shifting thermal gradients. Get rid of anything that causes or mind to timeslice. Focus. Focus. Focus. But, as Yoda said, don't TRY, DO. Then you'll be there, as close to one with the artist as possible. Or, is there more that can be done?

Just exactly how much does the appreciation of music have to do with the instrumentality of reproduction? Is it possible that we have gotten sucked into the pursuit of a red herring with a continuing and unreasonable focus on equipment at the expense of other, more important factors?

Sure, smaller drivers have greater dispersion at high frequencies. And, while back on the subject of equipment, why doesn't everyone that can afford it either tri or bi amplify? It's a hands down winner from EVERY single technical point of view. This should be a "case closed" topic, yet it is not. WHY?

Speaking as one who has a quad-amped system, I couldn't agree more.
As for connecting with the music (and speaking as a musician, myself), I've never been to a classical or jazz performance in the dark. Only on rare occasions have I ever heard rock in the dark. There was always some light, even if just light reflected from the stage. If there's no light in my listening room, to me it's just another reminder that I'm listening to a recording (I generally, but not always, listen with my eyes closed, but of course you're aware of light anyway even with closed lids). My buddy who listens in the dark feels that light is distracting, but I'm not clear why. I've never asked him if his eyes are open or closed in the dark.

Well, there are major and easily verifiable differences in the way that the retina responds to the following situations:

1. Light room, closed eyes.
2. Dark room, open eyes.
3. Dark room, closed eyes.

There is always visual noise. The less light, the more spatially homogeneous the noise seems to be.

So this could be a new line of inquiry for someone. "The signal to noise ratio of the mind and how it affects perception."

I have never been to a venue in the dark either. Imagine the problems. Anyway, part of the concert presentation is visual.

I think I will start an active crossover thread in the next few days. Jump in. If you should start it first, I'll jump in.
Sorry, forgot to throw something in. I frequently spend large portions of (at least classical) concerts listening with my eyes closed. So, for me, room-light-with-eyes-closed duplicates portions of my actual live music listening experience. The visual aspect of classical concerts is pretty tame--no fog machines, lasers, whatever. So I don't miss much by listening with eyes closed, and it allows me to remove a variable from comparison between live and reproduced. And, somewhat in the same vein you're describing, I hear more of the music if I'm not watching the bows go to and fro, or checking out the pretty cellist.

Glad to hear that.

For all that are following this, I think the following point is in order:

The view of your speakers, the wall behind them and all the other assorted paraphernalia in your room are not relevant to the reproduction of any kind of music regardless of where it is performed. These intrusions are NOISE. Not the kind of noise that most people consider to be noise but noise nevertheless. I don't see how they can be considered anything else.

Noise is something to be gotten rid of. It follows then that listening in pitch black is the only option for serious listening.
Thanks vdi_nenna, your comment is most gracious despite your fumblings with grammar.

Actually, I'd be quite worried if everybody liked me.

Tell me, are you one of those people who has to bask in the visual results of his own DIY accomplishments in order to enjoy the music? Do you gaze at your speakers in awe of your own greatness? Or, perhaps you are afraid of the dark.

Let us all know the answers to these nagging questions.
Subjective listening

So why do we do DIY? I think there are at least 2 reasons. One is to get the best sound possible, and perhaps the only way to do that is to build the system the way you want it. At the esoteric upper stratosphere of audio, it's probably cheaper to build it yourself. Getting it the way you want will be an iterative process, so plan accordingly.
The other reason is because it's fun to do, and it's something electronic you can build that is actually useful and achievable (don't see many DIY cell phones around).
I happen to fall in the latter camp. I like to look at what I built, but I'm certainly not in awe of my own greatness. My living room with the bay windows and couch will have to do. And if we happen to think it sounds better because we built it ourselves, that's perfectly okay.
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