Visaton 200B and 2x Eminence Alpha 15A

SteveRB · « **Reply #20 on:** 16 Jul 2011, 03:46 pm »

Thanks Rudolf. That's the type of response I'm looking for. But I'm a little confused of the 10% threshold. Can you explain it a bit further. My xo is near 220.

Thanks again.

Rudolf · « **Reply #21 on:** 16 Jul 2011, 05:14 pm »

Quote from: astronaut_glen on 16 Jul 2011, 03:46 pm

But I'm a little confused of the 10% threshold. Can you explain it a bit further. My xo is near 220.

10 % is just because you wanted some "basic rule"

Basicly you don't want the drivers a quarter wavelength or more apart. A quarter is 25 % and means a phase difference of 90°. That's were the summation of two waves starts to become really destructive. Since you want the crossover to behave well an octave below and above the nominal Xover frequency too, you cut that 25 % in half. And voila - my 10 % comes into sight.

It is just a cookbook rule. You may play with an applet like http://www.smaphysics.ca/phys30s/waves30s/waveadd1.html to get a feeling of phase relationship.

JohnR · « **Reply #22 on:** 17 Jul 2011, 05:34 am »

Quote from: Rudolf on 16 Jul 2011, 02:10 pm

If you want to align two true dipole drivers, NEVER do it by electronic delay.

Rudolf, are you sure about NEVER?

I do it, and if it causes a problem, it's not significant (in the measurements out the back of the baffle) compared to e.g. issues caused by using cone drivers. However by your criterion they don't need time alignment anyway

I do it because it ensures that the crossover integration is a piece of cake.

Doing something like a stepped baffle would have its own issues...

Rudolf · « **Reply #23 on:** 18 Jul 2011, 09:03 pm »

Quote from: JohnR on 17 Jul 2011, 05:34 am

Rudolf, are you sure about NEVER?

I was only trying to argue the Rick Schulz way - digital. That means: "real bad" or "super", but not much in between.

Quote

I do it, and if it causes a problem, it's not significant (in the measurements out the back of the baffle) compared to e.g. issues caused by using cone drivers. However by your criterion they don't need time alignment anyway I do it because it ensures that the crossover integration is a piece of cake.

John, now you already anticipated the answer:
"NEVER align two true dipole drivers by electronic delay, unless you have aligned them mechanically in a sufficient way beforehand."
I give you just one try to guess, what the next question from our beloved forum members woud be ...

Quote

Doing something like a stepped baffle would have its own issues...

Yeah, and those issues can indeed become more serious than a less-than-perfect-alignment. I've seen that with my own eyes - in measurements.

Rudolf

p2mc · « **Reply #24 on:** 20 Jul 2011, 03:41 pm »

Hello everyone. I am greatly interested to build the project, but I can not properly read the dimensions. Can anyone give me the dimensions?

Otherwise is can I replace the alpha 15a by Delta 15a, because I have a pair already.

thank you in advance

SteveRB · « **Reply #25 on:** 25 Jul 2011, 08:16 pm »

Quote from: p2mc on 20 Jul 2011, 03:41 pm

Hello everyone. I am greatly interested to build the project, but I can not properly read the dimensions. Can anyone give me the dimensions?

Otherwise is can I replace the alpha 15a by Delta 15a, because I have a pair already.

thank you in advance

if you PM me your email, i will send the drawings over.

p2mc · « **Reply #26 on:** 28 Jul 2011, 11:45 am »

hi astronaut_glen, i really don't know why i can't send a MP to you, but it's not important. i give you my second e-mail, and you will send me the plan.

in advance thanks

gg.toupin@gmail.com

JohnR · « **Reply #27 on:** 28 Jul 2011, 03:33 pm »

Quote from: Rudolf on 18 Jul 2011, 09:03 pm

John, now you already anticipated the answer:
"NEVER align two true dipole drivers by electronic delay, unless you have aligned them mechanically in a sufficient way beforehand."

Thanks Rudolf - sounds fair. Been struggling this evening with tweaking crossovers. So many infinitesimally small adjustments to be made! And then you wonder if perhaps a different mid would just solve the problem. Ah well.