5AS4 / 5AS4A Full-Wave Rectifier (Higher Max DC output current and peak current per plate than 5AR4, but 5AS4 is directly heated, recommended as an upgrade for a 5U4GB) - Sun Audio SV300B-MKII - Meixing Ming Da mc-7r 2006 pre - Audio Note Mono amps
5AS4A US Brands (5AS4=uprated 5U4GB) 1 tube $27) 5AS4A Raytheon NOS one small vertical scratch on base 1 tube $27) 5AS4A RCA branded GE NOS 1962 1 tube $27) 5AS4A RCA branded as Miniwatt NOS reboxed 2 tubes $27/ea) 5AS4A Sylvania NOS 1950's 0) 5AS4A RCA
Sonic Comments SONIC COMMENTS: -------------- 5AS4, as you described, seemed to open up the soundstage and improved the headroom, more macro-dynamic, just seemed to be stronger and more forceful. Bass was significantly more extended and detailed at the same time. Tonal balance was still even, despite improved bass, suggesting to me my previous rectifier tube was not as extended. (Mullard and AWV both came from the same factory, Amalgamated Wireless Valve Co, Sydney, Australia. Late 1960's) (These were very popular subs for 5U4GB, many were branded Super Radiotron, very good bass, lots of headroom, these 5AS4 blow away most 5U4GB ever made) SONIC COMMENTS: -------------- "Just wanted to let you know the Mullard 5AS4 tubes arrived yesterday - safely - and they sound great! These are much better sounding than the Philips 5U4GB's. The improvement is immediately noticeable. As always, thank you for the great recommendation, fast service and friendly communication. Bryan"