Swart AST MASTER Manual

AST MASTER Tech Info

Specifications

• All Tube circuit ~18-20w twin 6V6 High Class A Biased AB

• Can be powered by 6V6 and 6L6 (No KT-66, 5881, or EL-34)

• Tube stage Master Volume that is bypassable for Purists

• Cathode "AUTO" Biased (no need to bias)

• JJ & TS12AX7(3) - JJ 12DW7 - JJ 6V6 - JJ GZ34

• Tube Rectification ~ GZ-34 or NOS 5Y3 (See below)

• Sub NOS 5Y3 for earlier breakup/increased compression

• 100% Tube Reverb & Tremolo ~ Quality Spring Tank

• Hi/Lo Inputs for better PU Output matching

• Hand wired point to point ~ Made in USA

• Standby Switch ~ Amp warmed up|extends tube life

• Carbon Comp Resistors for BEST TONE

• Mallory, Sprague and JJ Caps, selected for Application

• Finest silver tinned cloth & Teflon covered wire

• Twin Outputs to run internal and EXT Cabinet

• 4 / 8 / 16 Ohm selectable ~ Rear Panel Switch
• IEC Fuse: 1A Slow Blow 20mm | HT Fuse: 500ma Long Fuse

• Dedicated 2 button foot switch included

• Extra Large Rubber Feet for Vibration/Protection

• As all Swarts, optional Export Transformer/Plug ~ $30

• Solid, finger-jointed Cabinet ~ Lacquered Tweed

• Dimensions: 20"H x 24w x 11 D ~ 39lbs

NOTES

TREMOLO in MV Mode
When in MV mode and you have the Master Volume at 3 or below, the TREMOLO, which is bias regulated, will be weaker. It's best to have the master volume at 4 or above for proper tremolo reproduction.
External Speakers
With the AST Head mk II,, you can run one or two speaker CABS. Please make sure to set the impedance correctly to handle the load. For instance, if CAB 1 8ohm option and you run an External 8ohm cabinet, set the impedance to 4 ohms for this load. If only running ONE cab, always plug into output 1.
NO power at all? CHECK IEC socket FUSE
This is the MAINS power supply fuse that is designed to blow if any issue threatens circuit. It cuts off the main power entering amp. Most miss this fuse as it's right adjacent to the plug entrance in a small compartment accessable with a small flathead screwdriver. There is one backup 1A slow Blow 20mm fuse within the compartment
see below

- Click above for full size-

See full size - Atomic Space Tone Amplifier

The heart of the matter - AST MASTER (same as AST HEAD II) Chassis with all tube circuitry - Click above for FULL view. See additional 4th 12AX7 dedicated to the Master Volume Circuit, totally bypassable for the purist. This unique Master Volume was developed to quell the potential leeching of TONE by the typical MV implementation. Swart would not marry a MV with the AST until a solution was found. We feel this is perhaps the best MV implementation out there.

~ Click above and below for full high resolution views ~

Internal & External Speakers
With the AST Master, you can run the INTERNAL speaker and an EXTERNAL cabinet at same time. Please make sure to set the impedance correctly to handle the load. For instance, if your internal speaker is the stock 8ohm option and you run an External 8ohm cabinet, set the impedance to 4 ohms for this load.

**NOTE: There is an extra Fuse located above the IEC socket. If your mains fuse is intact and amp won't power up, check this fuse by prying cover with flathead. You'll see the fuse plus one spare. Only use Slo-blow of equal value.
IEC Fuse: 1A Slow Blow 20mm | HT Fuse: 500ma Long Fuse .

CHASSIS REMOVAL
When accessing chassis, make sure amp is tilted forward. Inside four screws actually hold the CHASSIS to back panel. OUTSIDE SIX SCREWS remove the panel with heavy chassis attached. Be sure to take care in removing whole panel for ease of access. Tubes are held with wire holders. Take care in removal. Be sure to reattach before install.