Tube Audio Lab Western
Electric Model 91A 300B Stereo Amplifier
Model #: TAL Cantata 300B Stereo
Operation mode: 9 watts per channel, Pure Class A, Single Ended
complement: Output: 2x JJ 300B tubes, Input/Driver: 2x NOS Tung-Sol 6C6 (WE310A can also be used), Rectifer: 2x NOS Chatham
fully potted James 6123HS output transformer
- NOS Western Electric power transformer and Altec inductor
- Switchable filament power supply for 6C6 (6.3 vac) or WE310A
(10 vac) tubes.
All asc oil-filled capacitors(no electrolytic capacitor used)
- Angela Jensen/Jensen PIO signal caps,
- Western Electric bias meters for 300B tubes
- Brushed 12 ga aluminum top plate
clearcoated in automotive finish
- Custom-cut double enforced red oak base
- 100% point-to-point wired, no PCB used.
- Input impedance = 330k
- No negative feedback
- Gain = 22 dB @ RL = 8 ohms
- Output Impedance = 8 ohms (can be switched to 4 or 16 ohms)
- Net weight = approx. 80 lbs
The construction of this amp was inspired by Dixon Chen's WE91A-300B stereo. I made some minor modification to Joe Roberts' schematic of modernized WE91A to improve filtering in the power supply stage.
I was so impressed with the sound quality of his amp that I had to duplicate one (sans $500/pr Duelunds PIO caps). My only
stipulation in building another one was that it had to be better looking and had to be unique in some way.
As far as the aesthetics of the amp goes, I could not be happier than how
it turned out. It was an added hassle to build the wood base and to work on 12 ga aluminum plate, but the result was well
worth it. In terms of uniqueness, I achieved it by using an 500-0-500 500 mA NOS WE power transformer and an equally big Altec
choke that I have been saving for a big project like this one. I also added a switchable filament power supply, so that either
the 6C6 or the 310A can be used as a driver tube. I like using the 6C6s mostly because I can get quality NOS American brands
relatively cheaply, whereas the 310A does not give you such an option since it cost as much as the 300B. There are cheaper
Russian alternatives for the 310A, but I can't really vouch for their quality.
amps sounds great. It plays music with much authority and delicacy. The focus on music is on the performer and not on the
backround. You can still hear the background in detail, but it's not the primary focus. Great highs and mids. The bass is
tight and plenty, but not overwhelming. It's a nicely balanced amp.