TOPIC:

Hello,

I currently use my DDRC24 to actively bi-amp some Klipsch Cornscalas. Tube amp runs the tweeter/squawker with a 2 way passive crossover, and DDRC24 serves as upstream active crossover, with a solid state power amp directly driving the 15" woofer. I apply Dirac correction to this. I am about to get a nicer power amp for the woofers.

I want to know how I should account for the power difference between amplifiers. 
1. Put negative gain on the woofer amplifer channels, then run DIRAC
2. Leave both amps at 0dB, run DIRAC, and let it correct for the presumed overpowered low end and any peaks/troughs in that range

Previously I have used Option 1, which I assume is the correct way. But I am interested in opinions.

For option 1, the tube amp is around 15W, new power amp around 300W into 4Ohms - so I assume I would pad around 13dB.

Interested if DIRAC could potentially calculate the required gain via actual measurement etc. Given that driver sensitivity, impedance, passive crossover losses, power amp input sensitivity, speaker impedance all play a role - making my simple 13dB calculation likely too simplistic.

The power difference of the amps is irrelevant. What matters is any change in the gain of the new amp compared to the old one. More power does not automatically mean more gain.

What I would do is make a measurement in REW with the old amp and another with the new amp. This will show any difference in gain which you could then compensate for in the plugin (I'd use attenuation not boost to do so). Then run Dirac.

How would you do it from first principles? Since I probably never did properly for the old amp.

Would you just set DDRC Crossover point with 0dB on all channels, do a sweep in REW, at which point you would expect somewhat of a 'step change' between the 0-500Hz and 500Hz+? The level of the general/averaged step change would then be the attentuation for the new power amp?