hollowstate.netfirms.comWelcome to Mapletree Audio Design

Vacuum Tube Sound for the 21 st Century Mapletree Audio Design offers a unique range of products designed and hand crafted by Dr. Lloyd Peppard and Dr. Al Freundorfer, both electrical engineering professors. Our goal is to foster the enjoyment of recorded music through the use of vacuum tube amplification and signal processing, offered at a reasonable price. Click on the abov e tubes for more information Quick Find: Preamplifiers Power Amplifiers Headphone Amplifiers Routers and Switches SUMMER SCHEDULE Both Lloyd and Al will be taking a summer break until the end of August, 2020. We're happy to respond to inquiries, but orders will not be taken until the end of the month. Special - Custom LR 1 PRO Line Router LR1 PRO line router has 6 XLR inputs switched to two XLR outputs including one dual output. Priced at $300 USD. Contact Al Freundorfer for product details. MAPLETREE PRODUCTS PREAMPLIFIERS Line 2CRM Line Preamplifier (contact Lloyd Peppard for more information) Review of Line 2B SE by Tim Smith at wall of sound. Reviews The Line 2CRM is an upgraded version of the Line 2C line preamplifier w hich in cludes an Alps re mote volume control, IR receiver and handset at no additional cost. It also provides a Home Theater (HT) mode in which the selected input source is passed to the ou tput jacks, which are automatically disconnected from the active circuitry (the preamp can be turned off). Line 2CRM features include: • Premium passive components - Panasonic polypropylene film coupling capacitors and Alps remote volume control. • Optimized circuitry for lowest distortion and noise. • 3 inputs, 2 outputs, volume and balance controls. • Front panel Home Theater (HT) mode switch effective on all inputs. • 2 x 12SN7GT with rear panel switch for 6SN7GTB tubes. • Separate PS 2D power supply included. Download the User's Manual for more information NEW! Phono 3E Phono Preamplifier (contact Lloyd Peppard for more information) The Phono 3 E preamplifier incorporates low-level gain and phono equalization stages for moving magnet phono cartridges and is designed to operate in conjunction with the Line 2CRM line preamplifier . It has an output impedance of 2.5 kOhms, which can drive a reasonable length of interconnect without compromising the high frequency response. Noise at full output is less than 2 mV. It is designed to use the PS 2D power supply of the Line 2CRM with an extra power jack on the rear panel to permit connection of the PS 2D to both the Phono 3E and Line 2C RM preamps without any modification. Two switched phono inputs are provided, which can be ordered with custom loading specs. Tubes supplied are two new p r oduction 5751s and one NOS 12SN7GT. The compact PSX power supply is available for using the Phono 3E with other preamps/integrated amps. Details and full specifications can be viewed by downloading the User's Manual . BB (Black Buff) Line Level Buffer Stage (contact Al Freundorfer for more information) Layout designed to facilitate tube rolling. Sweeten the sonics of your DAC or other digital source with the Black Buff line stage. It features unity gain, 50K input impedance, less than 500 Ohms output impedance, and includes a volume control and heater voltage switch for use of either a 6SN7GT or 12SN7GT tube (supplied). Download the User's Manual for complete specs. POWER AMPLIFIERS Stealth Max Monobloc Power Amplifier (contact Lloyd Peppard for more information) Coming soon: Stealth Max II monoblocs . Contact Lloyd Peppard for more information. Delivers 50 W with KT88s running class AB 1 ultra-linear with fixed bias. Includes a triode mode switch. Built on a stainless steel Dynaco Mk III chassis with Mullard topology driver circuitry (6SJ7 voltage amplifier and 6SN7GT long-tail phase inverter), Dynaco spec output and power transformers, premium passive components, and a very stiff power supply. The sonics are effortless and open, espe c ially noticeable on high level transients. << Stealth Max system with custom passive stereo attenuator for use without active preamp. Super Stealth+ Monobloc Power Amplifier (contact Lloyd Peppard for more information) The Super Stealth+ monobloc power amplifier features proven Mullard driver circuitry and a 30 W power output using EL34 tubes. Tube complement: 12 SJ7/12SJ7GT, 12S N 7GT, 2 x EL34 Rectifier: full-wave solid state with ultra high-speed silicon diodes Output configuration: Class AB1 ultra-linear push-pull with self bias (EL34 matched pair recommended) Driver circuit topology: Mullard type with pentode voltage amplifier (12SJ7) and cathode-coupled phase inverter (12SN7) Rated power output (8 Ohms): 30 W Frequency response at 1 W output: 20 Hz–20 kHz –0.5 dB Gain: 27 dB (22.2) or 0.7 V input for 30 W output Input resistance: 100 kOhms Output resistance: < 1 Ohm Noise: < 0.7 mV (87 dB below rated output) Dimensions: 9.5"W x 13" D x 6" H overall Weight: 15 lb HEADPHONE AMPLIFIERS For a table listing the technical specifications of all the Mapletree headphone amplifiers, click here . Ear+ HD II Headphone Amplifier/Passive Preamplifier (contact Lloyd Peppard for more information) Reviews The Ear+ HD II is the latest edition of the Ear+ family of headphone amplifiers with new features including: • Front panel source selector switch for two line inputs. • Passive preamp output bypassing the active headphone c ircuit ry while retaining the source selector and volume control. • 2 x 12B4A NOS and 1 x 5751/12AX7/ECC83 tubes. • Low impedance headphone output compatible with a wide variety of headphone characteristics . • Premium passive components include Panasonic polypropylene output capacitors and Alps volume control. • Ultra high-speed rectifier diodes in power supply. DC heater voltage. • Textured black chassis with choice of natural maple, natural oak or black oak side panels. • Dimensions: 7.5" x 10" footprint x 5" tall • Weight: 8 lb OD300 SET Headphone Amplifier The Mapletree Audio Design Octal Duo (OD)300 Single Ended Triode (SET) Stereo Headphone Amplifier represents a high performance development of an octal tube based headphone amplifier. The use of a high capacity power supply provides increased power output and a lower driving impedance employing a widely available 6AS7G/6080 output tube and 6SL7/5691 driver. The separate power supply chassis allows flexibility in positioning each unit and reduces the heat seen by components in the main amplifier chassis. Download the User's Manual or contact Al Freundorfer for more information Headphone Guru Review: One Smooth Player NEW! Mellow Boy Octal Duo OTL Headphone Amplifier T he new Mellow Boy Octal D uo OTL (output transformerless) Headphone Am plifier employs an all-octal tube lineup including a 6336 output and a 6SL7GT triode driver stage . The high output power (over 1 W into 400 Ohms!) and low driving impedance of the 6336 easily handle any headphone sensitivity and im pedance characteristic. An innovative "mellow control" on the rear panel tailors the character of the of the music being played. Softest is when the dial is rotated completely clockwise and crispest when completely counter clockwise. For complete specifications, yo u can download the User's Manual or contact Al Freundorfer for more information Engineered To Order (ETO) Routers (contact Al Freundorfer for more information) Note: Images are shown for example only. Chassis and layout are selected to meet specific customer requirements. Customers often have specific requirements that can be met with custom features and/or modifications to existing Mapletree products. Usually, these can be accommodated at nominal extra cost. The most modifiable components are those disigned to route signals and/or reconfigure s ystem components, namely the LR 1 Line R o ute r, the SP 1 Amplifier/Speaker Selector , and the SCC 1 System C o nfiguration C o ntroller . Here is a brief summary of what is available. More information can be obtained from the Branches 7 Newsletter. LR 1 Line R o...