Here's the description Justin used to have for the Big Ben on his website:
Big Ben – Single Ended Stereo Tube Amp
The draw of single ended amps has always been realism and engagement. The Big Ben is setup for clarity over crazy power. Parts selection was crucial during this build and each was chosen not for price, but for quality of synergy between parts. Rectification is Solid State for cool running and reliable performance, again always over spec’d. The amp is configured for ultra linear operation allowing great power output and minimal use of feedback. The sonic signature is deep rich bass, and soundstage to die for.
Big Ben makes use of an over specified, extremely stiff power supply. The power supply is significantly larger than needed for primary filtering. In the early days of tube amps, chokes were easier to come by than caps and more reliable. As such, large chokes were utilized for primary filtering. As capacitor production gained reliability and costs lowered, cap filtering and smaller chokes became the norm. In a single ended designs, a regulated ultra quiet power supply is very important. Using a 5 Henry choke is expensive and large, but yields significant improvements in reduction of DC ripple.
Output transformers are over spec’d and ultra high quality. We consider the output transformer as important as any other design choice. When buying any tube amp, the weight of output transformer can be directly proportional to the quality of sound. In general, larger outputs have largers cores which are less prone to saturation and have higher inductance. Larger cores and greater inductances allows the transformer to carry a low-end signal with minimal distortion. These transformers are bench tested to perform down to 20hz and up to 20khz. Even if your speakers only go to 50hz like a LS3/5a having an amp with can drive that low impedence signal is pivotal in creating the whole sound stage.
Well paired speakers: Big Ben pairs well with most speakers 84db and above. Big Ben is ultra-quiet allowing use of full range or horn loaded speakers with efficiency above 100db. Speakers which can go down cleanly to 30hz really bring out the very best of the amp.
Our 3 Speaker suggestions:
1. DIY Econowaves (12” and a 1” compression driver; great sounding 95db efficient). 2. Klipsch horn loaded anything… Preference to Cornscala’s; (15” woofer with elliptical horn/2” compression driver and horn loaded tweeter with 1” compression driver 98db efficient and able to shake the house). 3. DIY/ampsandsound bass reflex cab ~.25cu ft with Fostex 103 4” or audio nirvana 4” ~approximately 89db efficiency. Probably not for a big room, but gives low 50hz response in a crazy small cabinet. Wonderful for near field, offices or small rooms.
The amp is compatible with all 6l6 family tubes, including 6l6GC, KT66, KT77, KT88, KT90, and EL34s. The driver tube is a 6SL7. My personal favorite currently is new EH6550 paired with new production Tungsol 6SL7 driver. For new old stock tubes, I like RCA 6L6GC clear tops.