Where can I read about CTC

[chrapladm]

about center to center (CtC), acoustical center and vertical polars?

I could just ask Zilch(PE forum) but I want to try and learn some of this stuff and I dont think I should burden him with every question. He does enough already.

I was learning about the E-waves and learning more about the CtC spacing and acoustical center importance.

I asked Zilch where do you measure Ctc from when trying to figure out the KH bass bin and mid horn.
KH is crossed much lower, so there's more leeway.

Hard to know without measuring what the vertical polar might look like, as the midrange from the woofer is "distributed." Gotta be nulls there somewhere, tho....
Thats what Zilch said and instead of just asking him everything I figured I would ask everyone else so I can try and figure out how to measure for myself all the needed parameters I would need.

I am not building any KH bass bins any time soon I am just trying to understand the science of everything Zilch has been doing but on a different speaker.

I have a few "Klipsch-esque," plans I have aquired and in a few years I will build them but for now I am just trying to learn.

Thanks for any help.

[Don Richard]

Is this something like what you are looking for?

http://www.audioroundtable.com/PiSpeakers/messages/11054.html

[chrapladm]

Yes this helps. Thanks

But the other question I was trying to figure out is what are the exceptable parameters for CTC distance?

And where do you measure the center at when using a horn such as the KH?

[Don Richard]

But the other question I was trying to figure out is what are the exceptable parameters for CTC distance?

It depends on the polar patterns of the horns (in a Khorn) and your desired lobe null angles. This is for the region of crossover overlap.

And where do you measure the center at when using a horn such as the KH?

From the centerline of the voice coils of the drivers. Note that with folded horns you also have path length differences that are much greater than the vertical stacking distances. In order to minimize lobing and comb filtering it is really necessary to time align the arrival of the sound from each horn to the listening position. This requires triamping and correctly implementing signal delays to the mid and high horns.

[chrapladm]

Thanks Don.

Thats what I was trying to undertsand. I new that vertical stacking wasn't going to matter as much in a horn as a direct radiating setup. I will have to keep looking but can you explain more on what would a desired lobe angle be of a given set system say the top of a Khorn?

I understand the time aligning as that to me seems to be most important when using different horn lengths for sound reproduction. I just have to learn more about the fine tuning of different horns placed together to accurately recreate recorded or live sound as it should be in a given room. I wouldn't know the correct questions to even ask, as where to start, but these answers have helped me answer some of the more common questions I have.

[Don Richard]

It would be hard to give any specific data because there have been several driver/horn combinations used in factory Klipsch through the years. Also, people have replaced stock components with Altec horns, JBL horns, Tractrix horns, Crites tweeters, etc. Generally you want the lobe null angles to match the vertical coverage angles of thespeakers that are being crossed over, at the crossover frequency. Note that this is not the "nominal" coverage angle spec. If a specific horn manufacturer does not offer directivity plots then you will need to run your own polars.