Biamping Dunlavy SC-V

Thanks both of you Sean and Tom. You have been tremendously helpful. You are very knowledgable Sean, you must have a technical background I suppose.
Well, the Acoustic Reality has an 8 kOhm input impedance, which is low. An Accuphase representative stated that that wouldn't be a problem with the C-290V preamp I am currently using. But when splitting the signal at the end of the interconnect the amp's input impedance is going to be... 4 kOhms, which is very low indeed. How can I raise the input impedance of the amp? Would be using two pairs of interconnects a solution? The preamp has two pairs of outputs. I've been told though that the preamp actually splits the signal that goes to the amps, instead of driving the two outputs actively. So it will also "see" halved input impedance.

Dazzdax: Now we are getting somewhere. 4K is too low for most preamps and will result in the exact problem that you've described i.e. bloated bass response and trunctuated treble output.

My Dad ran into the same problem in his system several years ago. The dealer had set him up trying to drive a 5K Ohm amp with a preamp that had a higher output impedance. The sonics sounded bad, but much of that was also a speaker based problem. In effect, his whole system sounded bad, so you couldn't really point the finger at any one given thing. In this regards, you might be a lot luckier : )

The simplest solution here is to install series resistors either at the output of the preamp or inside each of the amps. While this will attenuate some of the signal fed into the amps, it should solve much of the tonal balance problems that you're experiencing.

The key here is to find a value that is low enough not to eat up too much signal while being high enough to remove the current drain from the preamp. If you were happy with the tonal balance of the system using one amp per speaker and simply wanted better but equivalent performance, installing 8 K resistors in series with the input of each amp or output of the preamp would put you back appr where you started at.

Personally, i would install the resistors in the amp as that keeps the signal level higher through the interconnects. This is beneficial in more ways than one. Secondly, i would probably use resistors in the 12K region, as this would bring the total load up to appr 10K or so when running both amps in parallel. Even if you chose to run one amp per speaker, the input impedance would be 20K, which is still quite reasonable and easier on the preamp. You should also keep in mind that different brands and types of resistors have different sonic attributes, so you may have to pick and choose your poison there too.

You might want to discuss this with the dealer / manufacturer at Acoustic Reality and see what they suggest. Hope this helps and solves your problems. Sean
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Hi folks, I just want to let you know that the problem has been solved. I asked Peter Thompsen from Acoustic Reality and he has been very kind to get into some analysis of the problem. Due to his suggestions it is now clear what the culprit of the problem was: it was probably related to wrong pin configuration of the XLR plugs. Thank you Peter for your suggestions.

Food for thought. Picture an amplifer playing full range into a speaker load. By using two different terminals to feed the upper and lower portions of a system we still have an amplifer playing full range into a speaker load. Internally the crossover splits the signal but it doesn't change the amplifer playing full range. Now picture a speaker with a network that is designed to be crossed over externally. We supply an electronic crossover rolling off the amplifer at the desired frequency now creating a more efficient system. If a speaker can be driven without an electronic crossover it is not intended for biampflication. You may be doing more harm than good. Phase,alignment, load, etc. Food for thought.