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In Reply to: RE: It was not, no posted by MWE on September 25, 2020 at 10:36:53
That's why I am so excited to get these genuine Magnepan passive crossovers, so see how they should really sound! :-)
And I masy biamp the IIIas they way they should be biamped! :-)
Given the 18dB & 12dB XO slopes in the IIIa, the way they should be biamped is by:
1. not using the IIIa external XO box.
2. using a 2-way active XO after your preamp / DAC.
3. feeding the outputs from this 2-way XO into 4x identical monoblocs or 2x identical stereo amps.
The 2-way active XO can be either analogue ... or digital. (I started off with analogue active XOs - but, after nearly 20 years, changed to digital (miniDSP).)
One x/o that is capable of creating the high and low pass slopes required is the no-longer-in-production First Watt B4. I believe nelson Pass is now making it available as DIY kit. If you don't have electronic skills, you can look for someone who does to build it for you.
Here is a link to an article on the Pass crossover kit
Yes, there is a DIY project, Pass 6-24XO, that can do more than the textbook slopes. I have two of these boards on my desk. I do not like the electrolytics at in- and output. The impedance could also be lower. As Nelson Pass is the designer some guys get excited...
I don't know about the kit, but the factory-built B4 has an output impedance of 125 ohms. It has no coupling capacitors, the filter caps are Wima polypropylene, the resistors Vishay metal film. Good enough for me!
That is the B4. I refer to the 6-24XO that is available now as a DIY-project. I mean the internal impedance. The noise level can be influened by it. Good pratice is to stay between 4-15 k for the RC-links, not 10-60k as it is in the 6-24XO. That require bigger capacitors.
Getting rid of as many capacitors and inductors as possible between the power amps and drivers does a lot of good things for sound quality and efficiency.
Mark in NC
"The thought that life could be better is woven indelibly into our hearts and our brains" -Paul Simon
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