The JCA Circuits Golden Ratio GR 1.6 is a completely original guitar amplifier design. The amplifier concept has been created expressly to offer the finest sound, feel, versatility, control, durability, overall construction, and parts quality available. Each part utilized in the amplifier was chosen based on highest performance, finest possible tone, exceptional feel factor, and the highest degree of build quality. This amplifier truly is more than the sum of the parts.

Cocoa Levant With Small Weave Cane Grille (Click to image enlarge)		Cocoa Levant With Small Weave Cane Grille (Click image to enlarge)
We are able to offer the guitarist the finest amplifier quality, value, and service at a competitive price. Our personal standards have always been that the simplest of tastes are all that is necessary. We only require the best. The sound and feel of our amplifiers are the most serious aspect of our design. What good are the excellent parts if they can only produce mediocre sound? The JCA Circuits GR 1.6 is the premier medium powered combo amplifier. We offer the most versatile sounds and best playability of any vintage or modern combo amplifier in our power range. We offer every guitarist this exceptional design which will appeal to players of all styles. We feel that we are able to offer the most versatile single channel high end amplifier available. We enjoy listening to and performing many different styles of guitar music.
Black Levant With Salt & Pepper Grille (Click image to enlarge)		Black Levant With Salt & Pepper Grille (Click image to enlarge)

Features

• Cathode Biased 20 Watts RMS 6V6GT Duet Output Stage

• No Global Negative Feedback

• Vacuum Tube Rectifier Choices: 5AR4/GZ-34, 5U4GB, 5V4GA, 5Y3GT

• 12AX7 Based Preamp and Phase Inverter

• ¼" Thick Milled Aluminum Chassis—The Thickest and Most Durable Chassis Available

• All Stainless Steel Fasteners and Mounting Hardware

• Beautiful, Resonant Cabinets by Armadillo Amp Works

• Extra Heavy Duty Power Transformer by Dave Allen

• Extraordinary Custom Paper Bobbin Output Transformer by Heyboer Transformer

• Ultra Premium Celestion AlNiCo Blue 1X12 Speaker Option Available

• Ultra Premium Tone Tubby Ceramic Guitar 10 2X10 Speaker Option Available

• Exceptional Octal and Noval Ceramic/Silver Vacuum Tube Sockets by Angela Instruments

• Ultra Premium 2 Watt Mil-Spec Sealed Carbon Composition Potentiometers by PEC

• All Metal Input and Speaker Output Jacks by Switchcraft

• 1/8" Thick FR4/G-10 Garolite Circuit Boards

• Sprague ATOM Power Supply Filters and Bypass Filters

• Mallory 150 Series Coupling Capacitors

• Cornell Dubilier Small Value Coupling Capacitors

• 3 and 5 Watt Vishay/Dale Wirewound Power Supply Resistors

• 1 Watt Xicon Signal Resistors

• 12 Foot IEC Power Cord

• MOV AC Mains Surge Protection

Front Panel Controls

Input: ¼" input jack
Our Input is buffered and shielded to minimize interference and work seamlessly with effects.

The single input/channel style amplifiers are known for allowing the character of the guitar and player to best shine through. Small changes in the nuances of playing tend to be magnified utilizing this style of preamp.

Volume: knob
The Volume control increases or decreases the overall volume and distortion level.

Clockwise rotation increases the volume level. Changing the volume level also changes the distortion level of the amplifier. The Volume control can be set at a desired volume/distortion level and the overall volume can be controlled from the guitar itself. Back off on the guitar’s volume control and you will get a fabulous clean tone. Increase the guitar’s volume control and a fabulous distortion tone will appear. This is much more seamless and effective than channel switching.

Hi/Lo Tilt: small switch
The Hi Tilt setting emphasizes the thick upper midrange response of the amplifier and treble response of the amplifier. This setting cuts through the mix extremely well. The bristling harmonics make the 6V6’s sound other-worldly.

The Lo Tilt setting emphasizes the fat and tight lower midrange response of the amplifier. This setting is stunning for a multi-dimensional clean passages. Less bristling harmonics make the 6V6’s appear more sheer and elegant.

Lean/Plush: small switch
The Lean setting changes the frequency response and drive levels for a lean, biting, and dynamic push like no other. The imaging is more reserved while appearing a bit further back in the mix.

The Plush setting changes the frequency response and drive levels for a huge sounding, heavyweight tone. The sound is thickened considerably and the imaging appears closer in the mix.

Trim: knob
The Trim control allows fine shaping and tweaking of the Lean and Plush settings. This effect is absolutely amazing for tweaking your final sound.

Full counterclockwise rotation allows the minimum amount of Trimming of the Lean/Plush effect. At this point, the Lean/Plush effect is at a maximum level.

Full clockwise rotation allows the maximum Trimming of the Lean/Plush effect. At this point, the Lean/Plush effect is at a minimum level.

Treble: knob
The Treble control changes the overall level of treble response within the entire preamp. Clockwise rotation increases treble response.

Bass: knob
The Bass control changes the overall level of bass response within the entire preamp. Clockwise rotation increases bass response.

Cut: knob
The Cut control reduces treble response in the power amplifier section.

The Cut control is a tone control for the power amplifier as opposed to the preamp. This classic control is the best way to add "presence" to an amplifier without global negative feedback - like our amplifier.

Standby: large switch
The Standby switch enables the high B+ operating voltages for the vacuum tubes. The Standby is OFF when in the DOWN position. The Standby is ON when in the UP position.

Power: large switch
The Power switch enables the AC Mains power and allows the vacuum tube filaments to heat up. The Power is OFF when in the DOWN position. The Power is ON when in the UP position.

NOTE: First activate the Power switch for at least 2 minutes by placing the Power switch in the ON position to allow the tube filaments time to warm up. Once the filaments have had sufficient time to warm up, then place the Standby into the ON position to play the amplifier.

Pilot Lamp: indicator
The Pilot Lamp is the colored indicator lamp which shows that the amplifier’s Power switch is activated.

Rear Panel Controls

AC Cord
The AC Cord receptacle is where the detachable IEC Connector AC Power Cord plugs into the rear of the amplifier.

2.0 A Slo-Blo Acting Fuse
The 2.0 A Slo-Blo Acting Fuse receptacle is the AC Mains safety fuse. Use only a 2.0 Amp Slo Blo fuse in this receptacle.

4 Ohm, 8 Ohm, 16 Ohm Speaker Jacks
Each output tap is wired to it’s own discrete jack resulting in the least possible chance of impedance mismatching or outright failure between the amplifier and the speaker load.

0.5 A Fast Acting Fuse
The 0.5 A Fast Acting Fuse receptacle is the safety fuse that protects the output transformer in the event of output tube failure. Use only a 0.5 Amp (1/2 Amp) Fast Acting fuse in this receptacle.

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