Center channel connection

[davis419b]

Is it possible to use 2 Academy,s up front withj only one wire coming from the receiver ? If so what is the wiring procedure ?

[derrickdj1]

It is possible but, not needed or should be done.  What is the problem?  One center channel should be enough for most rooms.

[Chris A]

Just like batteries in series to increase voltage...connecting plus-to-minus connection between the Academies, and the remaining minus and plus terminals connected to your center channel amplifier circuit...it's much better to have 2x higher impedance than 1/2 lower impedance--like if you connected the terminals minus to minus, and plus to plus.  Having too low an impedance load can cause real problems with your amplifier. 

 

Adjust the center channel output gain to match the two fronts.  Voilà!  You're done.

 

Chris

[jjptkd]

I've ran dual KG 2.2's as a center before and it worked out great. I placed them end to end under my TV, called them my poor mans 64. I'd be careful on how you wire them as stated above, some Receivers can't handle a low ohm load and will likely trigger it into protection mode. If you want my advice, I'd sell both of those Academy's or move them to rear surround duty and buy either a RC-64 II or a RC-7, you'll be much happier with a single, nicer center speaker.

[davis419b]

33 minutes ago, Chris A said:

Just like batteries in series to increase voltage...connecting plus-to-minus connection between the Academies, and the remaining minus and plus terminals connected to your center channel amplifier circuit...it's much better to have 2x higher impedance than 1/2 lower impedance--like if you connected the terminals minus to minus, and plus to plus.  Having too low an impedance load can cause real problems with your amplifier. 

 

Adjust the center channel output gain to match the two fronts.  Voilà!  You're done.

 

Chris

 

I have been using 1 Academy for years and bought another one 2 years ago with this in mind. They both have Popbumper networks in them so they should match each other. One is great I just think 2 would be better. I will wire it like you said.

[davis419b]

26 minutes ago, jjptkd said:

I've ran dual KG 2.2's as a center before and it worked out great. I placed them end to end under my TV, called them my poor mans 64. I'd be careful on how you wire them as stated above, some Receivers can't handle a low ohm load and will likely trigger it into protection mode. If you want my advice, I'd sell both of those Academy's or move them to rear surround duty and buy either a RC-64 II or a RC-7, you'll be much happier with a single, nicer center speaker.

 

 

I think I want to stay with heritage centers to hopefully sonic maych my Khorns better.

[davis419b]

43 minutes ago, derrickdj1 said:

It is possible but, not needed or should be done.  What is the problem?  One center channel should be enough for most rooms.

 

 

1 is great I just want to see if 2 is better. The second was has just been sitting idle for 2 years.

[jjptkd]

Have you considered a single Heresy? They have the same tweeter and mid driver as the K-horn.

[davis419b]

6 minutes ago, jjptkd said:

Have you considered a single Heresy? They have the same tweeter and mid driver as the K-horn.

 

 

I have 2 extra Heresy's but they wont fit between my mantle and tv.

[derrickdj1]

Comb filtering may be a problem.  If you do run two speakers, wire them in series for a 16 ohm load.  This will reduce the amp power by 3 db.  Running to centers also looks odd, lol.  It does not do much for clarity or over all volume.  Now, if you had a really big screen with a low center ch. then one on top  or in the ceiling may work.  This would anchor the voices more in the screen than coming from below.

[Chris A]

1 hour ago, derrickdj1 said:

wire them in parallel for a 16 ohm load

Do you mean series (assuming 8 ohms per loudspeaker)?

 

1 hour ago, derrickdj1 said:

Comb filtering may be a problem.

Lobing is a concern starting at the point where the distance between the doubled drivers becomes 1/3 of a wavelength (just like La Scala, Belle, Klipschorn, or Jubilee bass bins). 

 

For two Academies laying flat on each other, that starts to occur at about 400 Hz.  Lobing will increase until you reach 1/2 wavelength--at which point you'll get a cancellation notch on-axis (about 600 Hz), then you'll have the equivalent of two sources with their directivity lobes based on 11" separation of sources.  There are more than a few people that use stacked loudspeakers that have problems that are in fact worse due to the increased distance between like drivers/horns.

 

Line arrays used at big concerts are much, much worse.

 

See: http://sound.whsites.net/articles/pa.htm#s4

 

One of the reasons why I pursued a coaxial arrangement of acoustic sources in the K-402-MEH, and why others use "D'Appolito configurations" in driver configurations (e.g., MTM, WMTMW, etc. using direct radiator drivers), was to avoid lobing issues, and thus preserve a point source output. 

[jjptkd]

I've read lots of times that running dual centers is bad, I've also done it several times with two side by side and one on top of the TV and one below. Improvements were marginal really but I did not notice anything wrong with the sound from doing it, I just decided it wasn't worth it. One big center is the way to go IMO but since you already have the second one you might as well try it out and see for yourself. Please post your impressions if you do!

[derrickdj1]

48 minutes ago, Chris A said:

Do you mean series (assuming 8 ohms per loudspeaker)?

 

Lobing is a concern starting at the point where the distance between the doubled drivers becomes 1/3 of a wavelength (just like La Scala, Belle, Klipschorn, or Jubilee bass bins). 

 

For two Academies laying flat on each other, that starts to occur at about 400 Hz.  Lobing will increase until you reach 1/2 wavelength--at which point you'll get a cancellation notch (about 600 Hz), then you'll have the equivalent of two sources with their directivity lobes based on 11" separation of sources.  There are more than a few people that use stacked loudspeakers that have problems that are in fact worse due to the increased distance between like drivers/horns.

 

Line arrays used at big concerts are much, much worse.

 

See: http://sound.whsites.net/articles/pa.htm#s4

 

One of the reasons why I pursued a coaxial arrangement of acoustic sources in the K-402-MEH, and why others use "D'Appolito configurations" in driver configurations (e.g., MTM, WMTMW, etc. using direct radiator drivers), was to avoid lobing issues, and thus preserve a point source output. 

Thanks for catching that Chris.  Series wiring would give the 16 ohm load.  Considering the negatives, there is not much positive to go the route of using two center channels.

[Chris A]

Well...increased sensitivity and lower modulation/harmonic distortion levels result from halving the load on each center loudspeaker (-3 dBSPL). 

 

Chris