Need help with amp schematic

[tromprof]

I am going to add a center La Scala between my k-horns. What I would like to know from those who have a better electrical knowledge is can I hook the 3 speakers to my amp as described:

The Jolida has three speaker terminals for each channel (Ground - 4 Ohm - 8 Ohm).

The Left and Right Heresy's were connect to Ground & 8 Ohm amplifier outputs on their respective channels.

The Center Speaker was connected between the 4 Ohm contacts of both channels. More particularly, the Ground of the Center Speaker was connect to the 4 Ohm terminal of the Left amplifier channel, and the Positive terminal of the Center Speaker was connected to the 4 Ohm terminal of the Right amplifier output. Note, for this to work, the two output channels have to share a common ground, which is how the Jolida is wired from the factory.

Can my Grant Fidelity safely do this as well? Attached is its schematic. I have other options to add the La Scala but would love to try this if there is no danger to the amp.

[Guest " "]

when you connect a speaker across two channels like you describe.....each channel see half the load.....so a 4 ohm lascala would put 2 ohms on the left and 2 ohms on the right.....your using a 4 ohm tap so this is problem number 1. Next we have a speaker already connected to each channel on the 8 ohm tap.....Heresy 1's are 4 ohms and Hersey 2's are 8 ohms....so the parallel combination of the 2 ohm lascala load and the hersey 4 or 8 ohm load is 1.3 or 1.6 ohms. It will probally work at low volues with out blowing fuses or over heating your transformers.....but I wouldn't do it at higher power levels.....best bet is to feel your transformers.....if they are very hot....not a good sign.

[djk]

"when you connect a speaker across two channels like you describe.....each channel see half the load..."

That is not correct.

The center channel bridged between the 4Ω taps is a trivial load for the amplifier to drive.

It will also not sound the best.

The center channel should be a L+R signal, but the center channel bridged between the 4Ω taps will only see a L-R signal. Loud passages in the bass are usually mono, so nothing will come out of the center speaker, and the amplifier load will not be affected. Since the difference between the two channels is small, the increase in amplifier power dissipation will also be small.

For a LaScala center between two Klipschorn the variable resistor would be replaced with a series LCR having the same impedance shape as the LaScala.

[tromprof]

Thanks for the help. It sounds like I could do this, but the better way is a separate amp. I have a Yamaha CA-1010 sitting unused at the moment. It has the ability to do a mono A+B out so I think I will start there. Operating in class A it sounds quite good. To get a signal to both amps I am planning on splitting the signal coming out of the DAC, do you think this will this degrade the sound? My other option is to split the digital signal instead and add a second DAC as well. I have a Behringer DEQ2496 available. Any thoughts are apreciated, I pick up the La Scala Friday.[]

[Exponential]

djk: I can't under stand your schematic. Are there five speaker boxes? Please clarity a bit.

tomprof: I looked carefully at your schematic, and it appears that the speaker outputs share a common ground, so you could use the PWK differential connection safely.

As for which center channel arrangement is preferred, I think this a very personal sonic choice. Although, I would say that a tri-amped power section fed from a line level matrix circuit would be a generallly preferred sesign. - - - - NEWBIE QUESTION - - - I there any way to make this forum accept carriage returns to separate replies into paragraphs?

[Guest " "]

the diagram does not represent the intentions by the op to use the 4ohm and 8ohm tap of each channel. If V=1 on the 4ohm tap, V on the 8 ohm tap will be V*2.

[Exponential]

" Loud passages in the bass are usually mono, so nothing will come out of the center speaker, and the amplifier load will not be affected."

This is only correct of the bass passage was recorded with a single microphone and mixed to both channels. In many recordings, the original audio will be gathered in stereo. Therefore, there will be a phase difference between the Left and Right channels, even from a single acoustic source. The phase difference signal will be reproduced by the L-R center channel. Thus the center channel introduce new a complexity to the experience.

[djk]

The L-R for the center will make it sound less like it would have in a live music situation.

The best way to do a center is with the PWK resistive combiner and another amplifier.

The drawing presents a passive 5-channel surround sound set-up driven with a 2-channel amplifier. The center speaker receives the proper L+R signal, and the rear speaker receive the L-R signal. The potentiometer connected L-pads provide level adjustments for the surround and center speakers. This set-up works best on speakers with a relatively flat impedance curve (which does not describe a Klipsch Heritage speaker). A parallel connected RCL network would be needed to replace the potentiometer for the correct center level with a Klipsch Heritage model.