Vacuum Tube Sound for the 21st 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 above tubes for more information

Quick Find:    Preamplifiers      Power Amplifiers     Headphone Amplifiers    Routers and Switches  

Please note: We will be closed for new orders for the month of August. For those inquiries we have on hand we will respond again at the beginning of September.



Line 2CRM Line Preamplifier (contact Lloyd Peppard for more information)
Review of Line 2B SE by Tim Smith at wall of sound.


The Line 2CRM is an upgraded version of the Line 2C line preamplifier which includes an Alps remote 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 output jacks, which are automatically disconnected from the active circuitry (the preamp can be turned off).

NEW!  In addition to the standard maple and oak, exotic hardwood end panels are available at no extra cost. Shown below (L to R) are:  Ebiara (Red Zebrawood), Yellowheart, Peruvian Walnut, African Sapele, and Roasted Ash.

Line 2CRM
features include:

• Premium passive components - polypropylene film coupling capacitors, metal film precision resistors, and Alps remote volume control.
• Optimized circuitry for lowest distortion and noise.
• 3 inputs, 2 outputs, volume (with remote), and balance controls.
• Front panel Home Theater (HT) mode switch effective on all inputs.
• 2 x 12SN7GT with rear panel switch for 6SNtGTB tubes                                          
• Separate PS 2D power supply included.

Download the User's Manual for more information

 Phono 3E Phono Preamplifier (contact Lloyd Peppard for more information)


NEW!  Custom side panels to match the Line 2CRM/PS 2D (above right shown with Yellowheart panels)

The Phono 3E preamplifier incorporates low-level gain and phono equalization stages for moving magnet phono cartridges and is designed to operate alone or 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 alone or shared with the Line 2CRM (a second power jack on the rear panel allows the connection of the PS 2D to both the Phono 3E and Line 2CRM preamps without any modification). Two switched phono inputs are provided, which can be ordered with custom loading specs. Tubes supplied are two new production 12AY7s and one NOS 12SN7GT.

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.


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 AB1 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, especially 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:  12SJ7/12SJ7GT, 12SN7GT, 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
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


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)


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 circuitry 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.

• Black powder coated finish with choice of natural maple, natural oak or black oak side panels.
• End panels are also available in the exotic woods shown above for the Line 2CRM.
• 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

Mellow Boy Octal Duo OTL Headphone Amplifier

he new Mellow Boy Octal Duo OTL (output transformerless) Headphone Amplifier 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 impedance 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 system components, namely the LR 1 Line Router, the SP 1 Amplifier/Speaker Selector, and the SCC 1 System Configuration Controller. Here is a brief summary of what is available. More information can be obtained from the Branches 7 Newsletter.

LR 1 Line Router - The standard version is designed to switch one of up to three input stereo signals to one of up to three outputs. Other configurations are available to handle up to 6 inputs and/or outputs. Chassis sizes are chosen to accommodate the required I/O connections. As with all the Mapletree switching components, RCA jacks are high quality gold plated with inside and outside hex nuts, switches are Lorlin or C&K enclosed rotary types with silver-plated contacts, and wiring is silver-plated stranded copper with Teflon insulation.


LR 1 Pro Line Router -
This is a balanced signal version of the LR 1. The standard model can switch up to  3 inputs and 3 outputs. Additional I/O can be accommodated using special multi-deck rotary switches. XLR connectors are Neutrik gold-plated type with locking tabs on the female version.

< Custom LR 1 Pro with 4 inputs and one output.             

"I received the switch [LR 1 Pro] today and it is exactly what I wanted and works perfectly - no noise at all when switching. I have bypassed my preamp for my DAC and LPs and have a sonic improvement".

SP 1 Amplifier/Speaker Selector
- The simplest (standard) version switches the stereo output of a power amplifier to one of two (or both) speaker systems. A typical modification is the addition of a switch for one or more amplifier inputs. All switches handling amplifier output or speaker connections are high-current rated versions of those employed in the LR 1 line router
. Multi (>2) speaker switching uses toggle switches (see below).  All amplifier inputs are terminated with suitable load resistors and binding posts are heavy-duty 5-way dual units.


SCC1 System Configuration Controller - This is a custom combination of the LR 1 and SP 1 that allows switching of several sources to one or more preamps or headphone amplifier, preamp outputs to one or more power amplifier inputs, and power amplifier outputs to one or more speaker systems. 

"[The SCC 1 is] simple elegant and effective. Does exactly what I needed it to do and has significantly reduced the effort involved in switching between components. Just a wonderful product".

    Custom SCC 1


For more information or to place an order, please telephone or email Lloyd Peppard or Al Freundorfer as referenced for each product or refer to price list tab

Telephone: (613) 387-3830

Email contacts:

Lloyd Peppard:

Al Freundorfer:

Mapletree Audio Design
158 Seabrooke Rd
R.R. 1, Seeley's Bay, Ontario, Canada K0H 2N0

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