Canned Crossover Design - What Next?

[ODougbo]

Pic of mock up of LEAP xo - DIY style (or very confused man )

Only one done, but parts needed may be today/tomorrow.

A few thoughts - the bass is nice, pretty darn full sounding. The tweeter is getting a workout, maybe more than I like for a inexpensive tweeter. The crossover point does sound even/smooth with generator sweeps.

Note 11 degree angle boxes from the top view

I'm really loving this box idea, it's way easier to make than it looks. I.e. cut a few groves on top and bottom panels - cut sides/back (12" - btw) and glue it up on corner of a table - it self alines. Used 4 - 6 penny nails to press back "in" while clamping down.
One thing I've been doing for back panels is gluing 2 - 1/2" sheets together for a 1" back - I highly recommend that ploy!!

[ODougbo]

more rabbits......Odougbo is on a roll.....

[ODougbo]

Tried the xo in last post - okay, thought I lost some bass with the 16g series woofer coil. I switched it out with a 14g and used 14g feed wires, quite the improvement (bass).

I thought the tweeter sounded a little hot on some songs, so swapped the 1st tweeter resistor; 2.2ohm with a 3.3ohm ....They sounds nice, they pound, kick, slam and have nice high end.

(ordered some steel lam inductors - will try that next)

[tvrgeek]

'Bout time to measure again. This time, with your stuff.

[ODougbo]

I thought this woofer was going to be a peaky monster when I took it out of the shipping box (large magnet) - and I guess it is, but with the cork/felt/large coil that's all gone.

The woofer circuit has the typical 3 parts to ground (besides large coil) coil-cap-resistor; I can't wrap my head around what that does

Also curious why this woofer is only $29, it's built really well, even self seals - but need to cut exact hole size!! I.e. if the hole is 1/8" to large, won't seal with out extra tape/sealer.

So yeah, amazing life-like guitar and bass strings, not sure if I ever heard a speaker so accurate.

btw, don't you have a pair of X25 tweeters? hint hint.

[wintermute]

Hi Odougbo, when you say coil cap resistor, do you mean in series and shunting to ground? If so then it is basically a "notch" filter. Effectively what it is is a bandpass circuit with a resistor to set how much cut you have. The coil sets the upper frequency range and the cap sets the lower frequency range. The resistor determines how much of the energy shunts to ground rather than going through the voice coil.

At least that is my understanding of what is happening, Someone jump in and correct me if I've got it all wrong

Tony.

[tvrgeek]

A Three parts in series, shunting the driver is a "series notch filter". It is a lot slicker than just setting two frequencies, as the cap and coil hey work in tandem as a resonant circuit at some center frequency. The resistor adjusts the depth of the notch. It works much the sale as a parallel trap, which has the three parts in parallel, but in series with the driver. This is to kill that horrible breakup the SF has.

Google Image Result for http://www.speaker-designer.com/mobile/images/series_notch_final.png

Redirect Notice

[wintermute]

A bit of googling showed that my description is off, in that as tvrgeek says it is a resonant circuit. I've done the parallel type notch filters myself, but have not tried the series ones (except in some sims) I found that the series ones seemed to be better for broad peaks which is what gave me the impression that the worked more like a bandpass circuit than a resonant one.

Tony.

[tvrgeek]

I have to laugh. We rely on Google and Wiki so much these days, we have been accused of not remembering anything. Freshman Engineering Orientation circa 1974: "Never memorize what you can look up. Understand the concepts and look up the details" I wonder Dean Blackwell would look at that now?

Use the parallel on tweeters and mids where the DCR of the choke is not an issue. The series notch is more often used on woofers as the DCR is not dropping the woofers efficiency. My experience, I will try a steeper crossover first, but I did use a notch on some Dayton RS's. Just don't put a bottomless (no resistor) series notch on a woofer as the amp will not like that at all. As a rule of thumb, I like to keep the smoke inside the wires.

[ODougbo]

There were quite a few posts on the X25 tweeter recently, and now has me second guessing if that was the best choice for this 2-way.

No complainants about the $29 SF woofer - Outstanding lower register/baritone and bass (with circuit shown).

The tweeter just seems to be "shining" but it's not that great. I have the X25 tweeter in Madisound HDS kits and the mid sounds are very smooth, however, they only down to 80 hz and these are rolling off into the low 40s

Any thoughts on tweaking?
Go find another tweeter ?