Let me start by saying that I have owned planar speakers exclusively since I bought my first pair of Magneplanars in 1986.
As soon as I saw Danny's video about the Carnegie CST-1s, I figured I needed to try them.
1. With the current lockdown and lack of GR Research speakers available for audition near me, I wanted to actually get to hear one of Danny's designs.
2. I wanted to see what an upgrade package could do to an existing speaker.
3. If I didn't like them I figured I could use them in a secondary system, or take them to my brother's house so I could have something to listen to when I visit him.
I'm glad I jumped when I did because Danny sold out before the end of the day I called.
I did listen to the unmodified speakers a bit to get a handle on the sound. They had promise, but I could detect some of what I don't like about box speakers. Was that some internal resonances? I'm sure it was.
I upgraded the crossovers first as I waited for answers on the use of No Rez - the purpose for this thread. I heard some detail improvement, but possibly too much as they became a bit bright. I initially had towed in the speakers and reduced that to get a better balance.
Once I finished the No Rez I listened again. I could detect much less boxiness. One of my reference recordings is the organ transcription of Pictures at an Exhibition by Jean Guillou. The deep organ notes were much more focused and solid. That even improved more once I put the last bit of No Rez in the chamber inside the lower port. I needed to clean out all the built up dust in the bottom of the speaker first and had been too tired for that when I tried to finish the No Rez the night before.
Once fully finished I began to listen more carefully. I had kept the speakers playing as much as I could since I got them to break them in. They had just been sitting in the room and I realized that sitting on two levels of carpet was not letting the speakers get enough floor loading - they were vibrating on a cushion of carpet.
I made the time investment to disassemble my Apogees and loaded stands. Being in my main speaker position really helped. I then added the spikes - I didn't want them on my good oriental rug. The speakers were still floating a bit until I added the spacers that allowed the points to dig down into the deep shag rug that is the lower layer in my room. Finally the speakers were on a solid foundation.
They were still sounding a bit "nervous" and bright. Possibly this is a factor from my years of listening to planar speakers that aren't known for the greatest dynamic swings.
I continued to let the speakers run overnight.
With somewhere around 150 hours of running, the speakers are finally coming into their own. I never thought I would like a box speaker this much.
I have always lived in fear of some of the organ music I like might eventually make the bass panels of my Apogee Stages rip apart. They made some protest if I turned up the volume too much. The CST-1s just take it in stride. I am amazed at the amount of bass these 5.25" drivers are capable of. A testament to Danny's transmission line design.
With more time on them, the "nervous" character is now gone. I won't say that they sound quite as effortless as my Apogee Stages on mid to high frequencies, but they continue to get much better. I just played the Les Brown direct to disc record I have had since 1978 and I don't have anything to complain about. It is clean and dynamic and free of almost all colorations - a window into the performance.
With the amount of effort needed to swap speakers, I am going to keep the CST-1s in place for a while to see how they continue to progress. No speaker is perfect, you have to balance all the factors. I like what I am hearing and if they continue to improve with more playing time, they just may be my new main speakers.
Equipment makes a big difference, so here is what is driving the speakers.
Turntable: SOTA Star Sapphire, SME 309 arm, Dynavector XX-2 MkII cartridge
Electronics: Audio Research LS-27 pre, PH-6 phono, DAC-8 for digital. Rogue Audio Medusa power amp
Wire: Kimber Select KS-1116 interconnects and 12TC speaker wire
If there is anything holding the new speakers back it might be the amp. It is way more than needed for these speakers. I needed an amp with lots of gain and watts for the inefficient and power hungry Apogees. Another lower gain and sweeter amp might be an even better mating.
As a comparison (not fair, but I'll make it): I gave a friend a pair of ELAC Debut 6.2 floor standers several months ago. While they are decent. They still sound boxy and these CST-1s are completely in another realm of sound. They should be for their retail price, but at the price I got these - and a bit of effort. They are stunning.