KT88
Mono Block:
Triode connected KT88s make BIG sound, excellent for
electrostatics. They feature a long-tailed pair input stage, DC coupled to
a long-tailed SRPP pair drive stage. Now on loan since I have become an single-ended amp
enthusiast. (Thumbnail shows original construction
before a complete re-design).
6SN7
PP
Line Stage: Intended for use with the KT88 PPP amps and
now on loan with those amps. It originally accompanied a CD player modified
using Sowter 8347 DAC mu metal cored step-up transformers.
EL34
PP Integrated: Incorporating a quality phono-stage, this amp can be switched on-the-fly between triode and
ultra-linear operation. Single stage gain/drive by true "long
tailed*" 6SL7 pair. *Pentode Constant current source. Now
modified to a 'power long-tailed pair' output stage topology.
6AS7PP:
4WPC Class A stereo amp. Using inexpensive toroidal power transformers for
the output transformers (credit to Steve Bench for this idea). The drive
stage is of the Mullard type, benefiting from later technology constant current
sources. The output stages similarly benefit, being configured as 'power
long-tailed pairs'. It is an excellent sounding economical and compact amp. Though a tube
rectifier is not shown, slow B+ turn-on is included to give the 6AS7 tubes an
easy life.
Calrad
SA30 Rebuild: I got this cheap via Ebay. A
lousy design with decent output transformers, it formed the basis for a fun
project.
