Akarakrit Uamkruea, blogger and audio gear maker who passionate in vacuum tube, audio & music.
Producing electronics projects since high school. Seriously upgrade and modify vintage audio equipment for “Real Sound” concept.
He is a co-founder of Soundaries, all audio solution provider.
Experienced and lively explore the listening rooms & audio shops in Japan as his most favorite to do.

Friday, December 30, 2022

Western Electric 6BP Audiometer transform to 95A Amplifier Part 2

After I published the first part in 2 months ago about planning to make 95A amplifier. 

Now I finish these mono-block amplifiers with some modifications from original schematic.

1) Using main power transformer instead of connect directly to power outlet

2) Using 80 full-wave rectifier tube instead of parallel 25Z5 tubes

3) Replace 221B with 221G choke (higher inductance)

4) Add WE313CC as voltage regulator & bleeding tube

5) Add LC filter to each screen grid for make lower noise voltage

6) Change some resistor & capacitor values based on real characteristic tube's curve

Expand some holes to put Neutrik connector both AC inlet (powerCON) and XLR input.

Almost US made components except transformers & choke from P&C Japan.

All 43 tubes are Raytheon 4 pillar (engraved base), 80 tube from Visseaux (France).

Top view


Techlab PK-322 600 ohm attenuator

Raytheon 4 pillar

Visseaux 80 tube

Bottom view

Speaker terminals

Ready to use

Neutrik powerCON AC Inlet

Neutrik XLR input connector

Original Schematic of WE95A amplifier

Schematic of modified WE95A amplifier

It's sound very good especially instrumental. Transparency & good tonal balance.

Maybe need more burn-in time to get it's real sound.

Finally I finish this project and post to this blog within 2022.

Happy new year to everybody!