Even the Martinelli Woodhorn projects 4 1/2" in front of the cabinet.
Does anyone know what the front to voice coil dimension is for the 416 woofer that would be in a true Model 19? Are the 2 driver voice coils in vertical alignment?

Thomas

It is important to know that the delay caused by the crossover is diferent than the delay caused by physical offset. Delay caused by physical offset is fixed but delay from crossover is variable, changing with respect to frequency. They don't cancel each other, so you can't align the system. But you can make it close enough to limit destructive interference that causes a sharp null at some frequency. That's what is really important.

Some suggest offset of one diaphragm in respect to another in order to counteract the delay caused by the crossover. To some degree, this makes sense. I take advantage of these kinds of relationships to allow flush baffle mounting of horns of various lengths. But I have long thought it was important to make it clear that this is not time alignment.

The best you can hope for is to configure the system so that two or more sound sources do not combine to form destructive interference in the target listening position. This is accomplished when sound sources are within about 120° apart, better if within 90°. You can't hope to align them perfectly, but if you can get them within +/-90° in the crossover range, then summing will be good. The idea is to prevent destructive interference from causing nulls in the target listening area.

• Baffle spacing, phase angles and time alignment, revisited

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13,5000 / freq(in hz) = wavelength

for 800hz = 16.875"

You want 1/2 wavelength (8.4") distance between the VC's using 2nd order crossover.

The 2226 VC is 3" behind the mounting backside.

Using 3rd order crossover, I don't know what to do. In the past I have used the same formula and it worked for me.

I currently have 2426J on Martinelli horns and trying to figure out where the VC on the 2426 is. On Altec drivers there is a metal band that goes around the driver that lines up with the VC.

Ron

The PCD tool below is a lot of fun to play around with to see the effects of different crossover order and frequency combinations, combined with driver offsets. You can import actual driver response and impedence for the modeling, or just use the default 90dB/w/m, 8 ohm settings.

Wayne explained it pretty well below, but it's fun to see it in graph format.

Gar.

• Passive Crossover Designer

Funny thing is I wonder if the crossover caps need some burning in yet as they are sounding kind of forward yet. I started out with a tube amp (Norh SE-9/SEP EL34's), and the sound was a little bit lacking. I then hooked up my Sansui AU-7900 which has been fixed/modded with Black gate caps and such, new outputs and driver transistors. A much better sound presentation. I will leave Bill to report on how they sound after his visit.

Thanks again Wayne!!!

Ron