Avantgarde Trios, SETs, and Impedance Curves

A friend of mine was using the 45-based Kondo, which realistically makes about .75-1 watt. This ought to be enough on the Trio, but he was unable to run the amp so there was not a high frequency rolloff.

The problem is that the midrange unit is not rolled out when the tweeter rolls in. This is because there are only caps in the crossover- no chokes to kill the highs to the midrange. The result is that the midrange is in parallel with the tweeter. The big horn OTOH is 19 ohms, but with the midrange and tweeter in parallel with it, you have a low impedance at high frequencies.

To make this work you have to play with the taps on your output transformer. The issue is that if you have a zero feedback amp (really about the only thing that otherwise sounds right on a speaker like this), you will not get the proper loading of the output transformer at frequencies less than that for the tweeter. The result is ringing (harmonic distortion) which obscures detail.

The end result is while you get the speaker and amp to work, neither is presenting the best of what its capable of. If, OTOH, the crossover were dealt with, this would not be the case. I would be very interested to see what that speaker could do then!! Given the cost of really good tube amplifiers, it seems that correcting the crossover would be a relatively inexpensive way to create a transformation.

For my TRIO Omega with a pair of Basshorns, I am using a pair of Antiphon Monolith 300B SET monoblocks. The Antiphons produce 7.5 perfect watts with lots of current reservoir (its power transformer is 600 watt capacity) Due to its enormous power reservoir and huge damping factor, it can drive a speaker with a very difficult impredance curve. I have directly and indirectly tried many amplifiers for Avantgardes, but nothing comes even close to the performance of Antiphons when it comes to driving a highly efficient speakers with huge drivers (15 inches or larger)such as Tannoy Westminster Royal HE, etc.
One of my friend is also using the Antiphons to drive his pair of Wilson Watt/Puffy speakers(known as a very difficult impedance load despite of its good efficiency at 92dB). The Antiphons surprisingly replaced his former amplifier, Boulder 2060 stereo amplifier. My other firends are satisfactorily using the Antiphons for Avalon Eidolons and Rockport Technology Antares.
As you can denote from the above instances, the Antiphons are outstanding at driving a speaker with highly fluctuating impedance curve.
If you want more reference or photos, please let me know.

Tron 300B amps are ok match for avantgarde Trio,but you will clip 300B tube, 8 watts, not enoughpower for trios complex load, this speaker withdemanding music can easily handle 50 watt peaks.

With my Trio 2.2s, later upgraded to Trio Omegas (huge difference, btw, like removing stuffed cotton from the horns), and using a pair of 225 subs in an 18 sqm room, I have tried Jadis 845, Zanden 300B, Hovland Sapphire, Lamm ML2, and Audion 300B power amps. The Lamms sound by far the most dynamic and detailed with full top to bottom extension, all other amps sounded somewhat anemic/rounded off though perhaps richer/more musical in some aspects. I have yet to find the sound I am looking for, but am sticking with the Lamms while I continue to tweak the rest of my system.

Has anyone tried the ART PX-25 or Wavelength Cardinal with Trios. Anyone else have any comments on 45 SET's with Trios.