We used a variety of amps in the lab and listening room. Threshold, Mark Levinson, Krell and Classé were always there. Unsound may be right about the TH12e, I don't remember. The Classe´amps were a pair of DR9s strapped to mono, which I still have, have hot-rodded and use every day. Their stereo rating is 8/4/2=100/200/400 and mono is 400/800/1100. An amazing thing to me is driving a pair of PowerPoint 1.2s, sealed box home theatre monitors rated at 89 db/w-m with 75 Hz cutoff into an easy room at "normal" playback levels . . . have you guessed? Their performance jumped a big notch going from stereo to mono with these amps. MUSIC IS TRANSIENT and impact requires power. These PPs are my mix and room monitors with stereo SmartSubs. (I'm still looking for a beat-up SS-2 or SW1). When people suggest your Thiels are sounding conjested on complex / demanding music, look to your amplifier.
An endemic design problem is second-guessing. If an amp designer assumes that low-impedance loads will be narrow-band / reactive, lasting instantaneous / short durations, then he can sign off on the particulars of his power supply. However, Thiel (and some other) speakers assume that a properly designed amp can deliver its rated output into resistive (easy) loads for longer term cycles (hard). The amp with enough power supply will love that load. The wimpy supply will starve the rails, clip the peaks, generally sound hashy and burn out drivers. I personally examined hundreds of burned-out Thiel drivers over my years (1975-1995) and every single one failed due to heat which means they were fed dirty signal. Conversely, over all the years of our listening and testing at well over 100dB (large) room levels, we NEVER burned out or otherwise failed a single driver. The specialty retailer and review magazines are supposed to do the educating, but that education is quite thin, in my opinion.
Jon, fiberglas is the cost effective standard. I tested and love genuine wool. Its naturally spiraled fiber works magic in converting pressure-motion to heat. We used 2 grades of SAE military pure wool felt on the back cabinet wall of the midrange enclosures to absorb the back-wave. Wool's performance can't be equalled by modern materials, which I call wishful engineering products. Wool fiber has a couple of problems in the cabinet. It acts very differently than fiberglas, so don't just replace the FG with Wool. And wool is inconsistent, so every cabinet would have to be trial-and-error optimized, which doesn't work well in a production environment. It is also hydroscopic (absorbs water in humid environments) and it's expensive. I will consider it if/ when we get to ultra-upgrade prospects, but wool must be re-engineered, not merely substituted.
An endemic design problem is second-guessing. If an amp designer assumes that low-impedance loads will be narrow-band / reactive, lasting instantaneous / short durations, then he can sign off on the particulars of his power supply. However, Thiel (and some other) speakers assume that a properly designed amp can deliver its rated output into resistive (easy) loads for longer term cycles (hard). The amp with enough power supply will love that load. The wimpy supply will starve the rails, clip the peaks, generally sound hashy and burn out drivers. I personally examined hundreds of burned-out Thiel drivers over my years (1975-1995) and every single one failed due to heat which means they were fed dirty signal. Conversely, over all the years of our listening and testing at well over 100dB (large) room levels, we NEVER burned out or otherwise failed a single driver. The specialty retailer and review magazines are supposed to do the educating, but that education is quite thin, in my opinion.
Jon, fiberglas is the cost effective standard. I tested and love genuine wool. Its naturally spiraled fiber works magic in converting pressure-motion to heat. We used 2 grades of SAE military pure wool felt on the back cabinet wall of the midrange enclosures to absorb the back-wave. Wool's performance can't be equalled by modern materials, which I call wishful engineering products. Wool fiber has a couple of problems in the cabinet. It acts very differently than fiberglas, so don't just replace the FG with Wool. And wool is inconsistent, so every cabinet would have to be trial-and-error optimized, which doesn't work well in a production environment. It is also hydroscopic (absorbs water in humid environments) and it's expensive. I will consider it if/ when we get to ultra-upgrade prospects, but wool must be re-engineered, not merely substituted.