Horn alignment....

[taotao]

Hi,

I completed my speakers with a tractix horn. See here: http://www.diyaudio.com/forums/showt...93#post1875893

My question: Is there a way to determine horn-alignement.
Oh, I know, you can measure, but can it be easier?
For example allign the coils of the drivers on one plane (seen from top down).

Or should the bms driver been put regressed on top?
Xover is 24 dB 800 Hz. I guess it can't be good for space-reproduction, if alignement isn't properly.

Thanks.

Olaf

[JEP]

Hi tao,

To measure is the most accurate way on listening position at the height of your ears. If the horn and fostexunit are about earlevel at 800 hz you can try putting the coil center a bit in front of the fostexcoilcenter because its freqencydependeble.

I think with 24dbfilters you dont need to worry that much cause the are less susepteble for missallignment. All within reason ofcourse


Fourth order crossovers
Fourth-order filters have an 80 dB/decade (or 24 dB/octave) slope. These filters are complex to design in passive form, as the components interact with each other. Steep-slope passive networks are less tolerant of parts value deviations or tolerances, and more sensitive to mis-termination with reactive driver loads. A 4th order crossover with -6 dB crossover point and flat summing is also known as a Linkwitz-Riley crossover (named after its inventors), and can be constructed in active form by cascading two 2nd order Butterworth filter sections. The output signals of this crossover order are in phase, thus avoiding partial phase inversion if the crossover bandpasses are electrically summed, as they would be within the output stage of a multiband compressor. Crossovers used in loudspeaker design do not require the filter sections to be in phase: smooth output characteristics are often achieved using non-ideal, asymmetric crossover filter characteristics.[1] Bessel, Butterworth and Chebyshev are among the possible crossover topologies.

Such steep-slope filters have greater problems with overshoot and ringing[2] but there are several key advantages, even in their passive form, such as a the potential for a lower crossover point and increased power handling for tweeters, together with less overlap between drivers, dramatically reducing lobing, or other unwelcome off-axis effects. With less overlap between adjacent drivers, their location relative to each other, becomes less critical and allows more latitude in speaker system cosmetics or (in car audio) practical installation constraints.

this is from the loudspeaker cookbook by Vance Dickason you can read it online at wikipedia

success roy

[taotao]

Yes Roy,

guess you are right: You have to measure it.
I know, you can observe it in an impulse response measurement.

I'll have to setup my measuring stuff and will do it some day.

Bye

Olaf

[norman bates]

since you have a 24db LR crossover, play some recordings with sharp sounds such as xyzlophone, keys jingling, woodblock, or scnare drum.

Have someone slide the horn forwards and backwards till it sounds best.

If I remember, you need to be +/- 1/4 wavelength at crossover point. So even if you are exactly lined up, you can be off by 1/4 800hz, so you can be plus or minus 4".

Norman

[Robh3606]

"guess you are right: You have to measure it.
I know, you can observe it in an impulse response measurement."

Yes that would be best but I simply set-up the offset using the voice coils and then designed the crossover for flat response and it came out pretty good. It may already be better than you think. You can also reverse phase a driver and use the deepest null to find the best alignment. They just set them up in phase.

Rob

[taotao]

Thanks Norman and Rob.

I think, I'll give this nulling trick a try and finetune by ear.

Have a nice time.
Olaf

[norman bates]

800hz is easy to get in, now 5khz, that's tougher !!!!!!!!!!!!!


Enjoy.


Norman

[JEP]

Well I totally agree!