Avantgarde Trios, SETs, and Impedance Curves

I guess I should check in here more often. I thought my thread was done in September. Thanks to all of you have responded here in November with some really helpful information and suggestions.

Ferenc, your comment on the Altmann amp is truly interesting. You're the first person I've seen report using the Altmann, and that you like it with the Trio tells me you are a man who listens and doesn't give one whit about the cosmetics of your amplification devices. I am also curious about your use of the REL Stentor II sub. I assume you have replaced the AG woofers, is that correct? Are you using one or two RELs? If so, at what frequency are you crossing into the REL? I didn't think the REL was able to go up high enough in frequency to mate with the Trio's lower mid horn.

711 smilin, the Mactone sounds very interesting as well, but given the inability to audition one with the Trios along with their cost, it probably isn't going to happen.

Atmasphere, it seems to me that you are saying that neither SETs nor solid state amps work properly with the AG Trios due to the Capacitors in the crossovers. Don't most speakers with crossovers use capacitors? Your comments seem to conflict with all the results of others who report very fine results with SETs and now Ferenc stating he is getting fabulous results with the Altmann amp, which to my knowledge (correct me if I am wrong) doesn't use any feedback just like most of the SETs that others have found favor with. Yet you claim that an amplifier with feedback is required in order to achieve proper results. It does make one wonder.

I think Atmasphere is saying that some SET's have trouble with the tweeters crossover. My 845 amps sound very extended on top. They are very powerfull for SET's though. I have heard from others that 300b amps have no problem also. Wavelength recommended to me there 300b Cardinal over their lower powered amps for trios. I will be trying a Wavac 300b next week and will give my comments later. It sounds like some of the flee powered SET's might have problems with trios. Many people use them though, so they should be auditioned first.
Steve.

I would like to add one more thing that I forgot. I talked to Jim Smith last week on the phone. He no longer represents Avantgarde, but still answers the phone and gave me his opinion on amplifiers for Trios. I hope you don't mind me quoting you Jim. I was interested in maybe a ART px-25. He said that he thought the ART px-25 was a very good amp. I didn't ask him about the Audiopax which he also sold. I asked him about my amp, 845 Viva Aurora Monoblocks, which he did sell at first with Avantgarde. He told me that if he was stranded on an island and had to choose one amp for the rest of his life it would be the Vivas. It was a nice comment to hear from someone so respected in this industry. Jim says he has closed the distributorship business for good. I don't see any gain to make a biased comment. I still would like to try a low powered like px-25 or 45 tube. I have to hear it one day for myself. There must be other Trio owners out there with other amp comments. Also, anyone in the Vancouver, Canada area with a flea powered that would like to hear on Trios let me now.
Steve.

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.