Project Horizon 3.1 - Tube Headphone Amplifier and Pre-Amplifier:
Project Horizon is a sister amplifier to Project Sunrise III even sharing the same PCB. Understanding the want and need for a version specifically built for high impedance headphones, Project Horizon was born. Horizon costs a bit more than Sunrise III as it takes quite a few more parts and a much higher voltage power supply. Horizon is quite a beast and just like Sunrise III, she is very musical and offers loads of adjustability combined with the ability to roll a ton of tubes. Horizon is a real staple to our lineup and also has been reviewed and loved globally!
New features of Horizon III:
- Revised layout
- Line-out bypass (when headphones are plugged in)
- Variable input gain with easy to swap gain module
- Revised protection circuit with LED indication
Features of Horizon:
- Easy Set bias via LED indicators. No need to use a multimeter anymore when rolling tubes! Access from the side of the amp, no removal of top cover
- Easy access to bias trimmers. You can use a jewelers screwdriver to dial in the bias through the top cover, no need to remove the cover to set
- Access to the 6/12V jumper through the top cover, no need to remove the top
- Output impedance selection can now be set from each side of the chassis
- Line output for pre-amp use
- Revised protection circuit protects your headphones and audio gear
- Revised circuitry overall
- Designed in the U.S. & Netherlands. Kitted or Built in the U.S. depending on how you order / 5 YEAR WARRANTY ON G1217 BUILT AMPS!
- All parts sourced in the U.S. From reputable distributors, NO FAKE COUNTERFEIT PARTS, CAPACITORS OR RESISTORS!
- Only top quality components used, such as Bourns pro audio potentiometer, Bourns trimmers, Low noise Vishay/Dale RN, CMF and CPF 1% resistors, Nichicon Roederstein capacitors, Fairchild IRL510 Mosfets & top quality LM317HV’s used, Neutric phono jack. Ruggedized PCB RCA jacks, Rugged 5a power switch ETC… RCA's, tube socket, phono jacks and even jumpers are gold plated
- Beautiful piano gloss black .096 thick double sided, 2oz PCB with top and bottom ground planes & gold wash. Will not bend or flex while inserting a tube!
- Dedicated heater power supply, no piggy-backing off LM317's which is a cheap, non desirable way of powering the tube heaters
- Turn on / off protection for your headphones and audio gear
- Supports a wide range of 6V or 12V tubes with voltage selection
- Built in test points to easily and quickly dial in bias or dial in bias via the Easy Set LED indicators!
- Class A, No overall Feedback
- Fused with reverse polarity protection
- Chassis is beautifully laser cut and serialized.
- Chassis hardware features all stainless steel allen bolts, washers and nuts. Stand-offs are aluminum along with top cover thumb screws
- Each factory built amplifier is meticulously hand built and tested prior to shipping. Solder work is outstanding and clean with no flux or fingerprints left on the board. Pride in workmanship is evident from every angle of this amp. What you see in photos is the quality of build you will get!
- An RGB LED is available under the tube which can allow you to turn the tube ANY color you desire via 3 trimmers, or cover the LED so all that you see is the glow of the tube!
For Advanced Tuners:
- Input capacitor section is drilled for multiple capacitor footprints. 2, 2.5, 3.5, 5 or 7.5mm spacing available
- Output capacitor section is drilled for 7.5mm
- Power supply capacitor section is drilled for 7.5mm
- Input capacitors can be bypassed for optimal sound (can result in a scratchy sound only when adjusting volume)
- Variable output resistance, selectable from 1.5, 35 and 120ohm
Actual Project Horizon Measurements
- Single ended OTL class-A output stage.
- Power consumption: 13W continuous, 19W peak.
- Power supply: 48VDC (0.55A cont, 0,8A peak)
- Input Resistance: 11k / 31kOhm gain module dependent
- Input Sensitivity (6N23): 270mV (dependent on tube)
- Gain: 20dB (dependent on tube) Changed from the original higher 26dB specification
- Max Output voltage (no load): 14.1Vrms at 300ohm
- Output Resistance: Selectable 1.5, 35 or 120ohm
- Frequency Response: 10Hz – 160 KHz (-0.5dB) with 32ohm load
- Frequency Response: 4Hz – 400 KHz (-3dB) with 32ohm load
- Signal to Noise ratio: 91dBA (dependent on tube)
- Crosstalk: -88dB (dependent on tube)
- THD: > 0.013% (dependent on tube)
- Suitable for: 120-600ohm Headphones
- 6.5L X 5W X 2.75H in inches
- Acrylic Chassis 1lb (without power supply)
- Aluminum Chassis 1.34lb (without power supply)
Optimized for Headphones 120 - 600ohm | Shown in both aluminum and acrylic chassis options
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