Is it ok to Bi-amp using different Brand/model of
Hi Stanwal, Thanks for the input. The Marchand active XO does have attenuation for each Hz section. My concern is different input sensitivity of the amps. The VK-60 is 1.0V. The SS BAT amps are rated at 1.5V. Does this mean when adjusting the volume on the pre-amp the gain on the two amps change at different rates. That is, do I need to re-adjust the level controls on the Active XO to balance the gain on the woofer and mid-tweeter sections with each diffent pre-amp volume settting. |
No, all you need to do is to set the relative level once and since both will receive a signal that varies in the same way from the preamp they will stay in balance. If one were coming from a fixed output like tape out then you would have to rebalance them. I often use subs powered by amps different from my main amps with no problem, you just have to set the level relatively higher on the less sensitive amp. For example my Meridian 605s [main amps] have a ,5 volt sensitivity and my Tandberg 3026A is [I think] 2 volts but I have had no trouble using them together using the crossover level control. Once you have it set they will stay in balance. |
My concern is different input sensitivity of the amps. The VK-60 is 1.0V. The SS BAT amps are rated at 1.5V. Does this mean when adjusting the volume on the pre-amp the gain on the two amps change at different rates. That is, do I need to re-adjust the level controls on the Active XO to balance the gain on the woofer and mid-tweeter sections with each diffent pre-amp volume settting.No, once levels are matched between the woofers and mid/hi drivers, they will stay matched as you change the volume control setting. BTW, what you are matching is amplifier gains, not sensitivities. The sensitivity of each amp is the input voltage it requires to reach its particular maximum rated output power. For instance, if all of the speaker's internal crossover elements were in place, and you were to drive the woofers with a 200W amp having 1.0 volt sensitivity, and you were to drive the mid/hi's with a 100W amp also having 1.0 volt sensitivity, the input to the 200W amp would have to be attenuated by 3db for a proper match. The fact that you have the speakers' mid/hi crossover elements in place, with the woofers' crossover elements removed, complicates things a bit further, because the crossover will introduce some loss at mid/hi frequencies but not at low frequencies. But once you obtain a satisfactory volume match, it will not have to be readjusted as you change the volume control. I'm wondering, though, about crossover slopes. I note in Figure 3 of Stereophile's measurements that the crossover slopes of the mid/hi section appear to be asymmetrical with respect to those of the woofer section (approximately 24db/octave for the woofer section, and close to 12db/octave for the mid/hi's), although that figure presumably represents the combined rolloffs of both the crossover network and the drivers. If you are saying that in your setup only the active xo is rolling off the woofers, while both the active xo and the internal xo of the speaker are in the path to the mid/hi drivers (with all of the crossover points being about 550Hz), it seems to me that (depending on what the active xo slopes are) you may be making the overall crossover characteristic significantly different than what was provided in the original design. Regards, -- Al |
