series Vs parallel passive Xovers

[Puggie]

I understand parellel passives, they easy and simple, now I've read the humble homemade hifi pages about series crossovers and I understand the theory of how they work. Would anyone care to comment on the relative merits and failings of both systems? what do people prefer. I currently have a set of small bookshelves with a simple 1st order Xover and L-pad (its a bit lopsided Lpad but it flattens the top end nicely). I'm considering having a bash at a series crossover for that as a start point.

Any thoughts on the subject in general anyone?

[rabbitz]

Have a look at some info on Andy's site.

http://users.tpg.com.au/users/gradds...ross-overs.htm

There's reasons for using both types but since you've got a 1st order all ready in there, give it a try as you might get a surprise..... require a bit of testing to get right but very worthwhile. Series are driver dependant and don't tolerate drivers that aren't well behaved.... need a smooth roll off and no nasty peaks and humps.

Been my xo of choice for quite a while since Andy pointed them in my direction.

[Dick West]

I thought the comments on the Humble Hi Fi web site were spot on. They said it all about as best possible.

I am using nothing but serial xovers here. They are just more "musical" to my ears. But, a previously stated, the proper choice of drivers is absolutely required. Also, for some hi power hi decibal applications one must stay with the parallel xovers as they can better attenuate out of passband loads to the drivers.

But, experiment. Try it and maybe you will like it. . . .

[Cal Weldon]

Originally posted by Dick West
Also, for some hi power hi decibal applications one must stay with the parallel xovers)

Thanks Dick,

I think that's a useful thing for people to know.

Cal

[Geenius]

Series are driver dependant and don't tolerate drivers that aren't well behaved.... need a smooth roll off and no nasty peaks and humps.

.....when using first-order series networks.

If you use 2nd order (at least on the woofer) you can add LCR notch filters parallel to the woofer. I have used several Seas aluminium woofers with series crossovers and they work very well.

[Puggie]

Oooh the spreadsheet looks handy to get somewhere close as a start point.

I'll have a play when Audiocominternational finally deliver my CAPS!!!!

I'm playing with Morel and C-quenze drivers so quite well behaved with no nasty breakups. Series crossovers seem a rarity but everyone who seems to use them speaks very highly so must be worth a go.

[Ropie]

Originally posted by Puggie
I'll have a play when Audiocominternational finally deliver my CAPS!!!!

Argh! Don't mention that name (I waited 9 weeks for some Black Gates a couple of years ago)!

[Dick West]

Puggie,

Series crossovers seem a rarity but everyone who seems to use them speaks very highly so must be worth a go.

Parallel crossovers are easier to design and more software is available to do so, therefore a speaker manufacturer can knock out a design with less R&D expense.
Plus the parallel designs are more tolerant of the slight driver variations that often occur over a period of time with many different manufacturing runs of the drivers chosen. It is easier to make money from parallel xovers than from serial xovers. My $0.02

Series xovers have an elusive quality and they are very driver dependent. One change in a part of the network effects all the rest of the network so one can get into a lot of iterations to achieve the final goal. However, once you get it right you can almost hear the sound "gel" in your room as it all becomes coherant and musical.

Keep us informed as to your driver choice and xover schematic.

[soongsc]

What's "zeta" of a crossover?

That "conversation with the Ultimate Monitor Designer" is really clear and to the point.

[Dick West]

Serial xovers have been discussed in great depth 3 years ago at the Madisound board. Here is a part of a small "white paper" written by Ken Perkins. Check messages by Ken and John K.

"The biggest confusion has seemed to come from the term "zeta". As John Kresovsky describes it in his excellent papers, zeta is simply a description of the damping of the circuit. Butterworth values in the circuit give zeta = 1. Zeta less than 1 is an underdamped circuit, with a slight peaking overlap at or around the crossover frequency. The circuit will typically be more capacitive as it uses a smaller choke and larger capacitor than straight Butterworth. Zeta greater than 1 is an overdamped circuit, with a slightly sagging underlap at or around the crossoverfrequency. It is more inductive than Butterworth, using a larger choke and smaller capacitor. As would be expected, the lower zeta values will give a slightly more than 6 dB/octave roll off due to the peaking. A zeta of .5 gives a nearly 12 dB/octave roll off. A zeta of .7 is nearly 9 dB/octave roll off and as zeta goes up, the roll off becomes even more gradual. Thus the need for a really beefy tweeter and a woofer that can play cleanly at the top limit of its range for high zeta. In my opinion, zeta should not necessarily be the target for the design. It's the result. The crossover frequency you choose is the most important consideration. When the right blend of drivers and crossover have come together, you can then determine what the zeta is."

Also, study comments at the Humble HiFi web site mentioned by the OP. In this write up curves were shown for various combinations of coil and cap values. I don't recall that "zeta" was mentioned but it would relate to the above comments about zeta and higher/lower values of coil/cap around the same target xover point.