MS-2a
Chassis for Single ended and Push-pull
monaural amplifier

An upper amplifier was completed by installing the transformer etc.

MS-2a is a suitable chassis for producing 300B, 2A3 and 45 etc monaural amplifiers with R core transformer.

1. Feature

Chassis for Single ended and Push-pull monaural amplifier.
Portrait shape. When two is arranged, it is width of an almost standard stereo amplifier.
Front panel and exterior and interior parts.
Gold-plated input terminal and gold-plated speaker terminal.
It suits our R core input transformer and output transformer.
It suits the power supply transformer and choke coil by NOGUCHI and KASUGA co.
Composition of tubes
One MT 9pin tube and three UX or US 8pin tubes.
The tube socket is included.
Size W:170mm, D:400mm, H:75mm
Price US$150 (excluding tax & shipping).

2. Assumed circuit configuration

The amplifier of the following circuit configurations is assumed in MS-2a.

Single ended amplifier
Driver tube 1 (MT 9pin)
Driver tube 2 (US 8pin or UX)
Input transformer
Output tube (US 8pin or UX)
Output transformer
Rectifier tube (US 8pin or UX)
Push-pull amplifier
Driver tube (MT 9pin)
Input transformer
Two output tubes (US 8pin or UX)
Output transformer
Rectifier tube (US 8pin or UX)

3. Parts that can be installed

Tube	One MT 9pin tube and three UX or US 8pin
Input transformer	Softone RC-20 TANGO NC-2X series
Output transformer	Softone RW-20, RX-40-5, RX-30-8 TANGO FX-40.
Power supply transformer	NOGUCHI PMC-150M, PMC-170M, PMC-190M. KASUGA O-BS500, O-BS700
Chalk coil	NOGUCHI PMC-1520H, PMC-1030H. KASUGA KAC-5250, KAC-2012
Input potentiometer	Cosmos: RV24YN type potentiometer, Softone: mini attenuator, Alps: 27 type potentiometer.
Hum balancer	Cosmos: RV30YN type potentiometer

4. Chassis upper shape

From the left upper sequentially

Hole for input transformer
Hole for output transformer
Hole for choke coil
Hole for power transformer

From the left under sequentially

Hole for MT 9pin driver tube
Hole for two US 8pin or UX tubes
Hole for hum balancer
Hole for US 8pin or UX rectifier tube

The hole for the installation of two 10pin T terminal boards is in the top and bottom of MT 9pin driver tube.
There is a hole for the installation of two 5pin T terminal boards between two US 8pin or UX tubes.
Cosmos RV30YN type potentiometer suits the hum balancer.
Because the hum balancer is not used, the cap is attached.
The bridge diode for the DC filament ignition or Lagu boards can be the installations on two holes at the right of the rectifier tube.

The shape that socket etc. are mounted

5. Shape in the front of chassis

The front panel adheres in front of the chassis.
The power switch and the input potentiometer are installed.
Cosmos RV24YN type or Softone mini attenuator,
Alps 27 type suits the input potentiometer

6. Shape on the back of chassis

The input terminal, the speaker terminal and the AC inlet with fuse holder are installed the back side of the chassis.

7. Examples using MS-2a (MS-2)

8. Parts list

Parts in the table below are included in MS-2a

Names of parts	quantity
Main body of chassis	1
Front panel	1
Bottom plate	1
Input terminal	1
Speaker terminal red	1
Speaker terminal black	1
AC inlet	1
MT 9pin socket	1
UX socket	3
US 8pin socket	3
AC code	1
rubber foot	4
Power supply switch	1
Volume knob	1
10pin T terminal	2
5pin T terminal	2
Small knob	1
9.5mm black plastic cap	1
10mm white plastic washer	2
10mm tooth lock washer	1
3X6 black truss screw	8
3X8 black cap screw	4
3X10 black screw	7
3X15 black truss screw	14
3mm spring washer	15
3mm nut	15
4X15 black truss screw	4
4X20 black truss screw	2
4mm spring washer	6
4mm nut	6
Faston terminal	7
Manual	1

The following parts are not included in MS-2a.

Vacuum tube
Potentiometer
Transformer
Resistor
Capacitor
Lagu boards (Two 10pin T terminals and two 5pin T terminals are included)
Wire
Tools

Ordering

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MS-2a Chassis for Single ended and Push-pull monaural amplifier