Vacuum Tube Sound for the 21st Century

Mapletree Audio Design offers a unique range of products designed and hand crafted by Dr. Lloyd Peppard, a retired electronics engineering professor. The goal is to increase your enjoyment of recorded music through the use of vacuum tube amplification and signal processing. 

Click on these tubes for more information ^^^^^^^^^^

Quick Find:    Headphone Amplifiers   |   Preamplifiers  |   Other Products (line routers, Dynaco driver board, power amplifiers)

Customer Photo of the Month: Jeff Kew: Ear+ HD Super II


Fall Specials

SOLD OUT  • 12SX7GT upgrade for prea
mps. While supplies last, customers will receive NOS (or strong OS) tubes in place of the stock 12SN7GTs. This means a pair of 12SX7s for the Line 2B and Ultra 4B and a single tube for the Phono 3. The 12SX7 is considered by many to be the ultimate audio tube in the 12/6SN7 family. This is a $50 value.

• Free shipping to N. American locations and a $30 credit for international customers.

• Remote Control review unit. The RM 1 Remote Control for the Line 2 preamp reviewed at wall of sound is for sale for $300 with new warranty. This can be used with any of the Line 2 preamps or the Ultra 4 (line inputs only), and includes a replacement power interconnect cable to supply power to the remote unit. Black chassis with anodized aluminum front panel; black oak end panels.



Go to:   Preamps  •  Headphone Amps   •  Other products (Power amps, Dynaco ST70 driver module, Magic Eye monitors, Line Routers)

NOTE: All MAD components, with the exception of the Super Stealth and Stealth Max power amplifiers, are available for 230-240 VAC 50 Hz at no extra cost. Super Stealth and Stealth Max monoblocs for 230-240 VAC are available at a slightly higher price.  

Chassis colors include RCA red, textured black, Sylvania yellow, eggshell white, cobalt blue, and sage green. Side panels are available in black or stained oak.


New! A comparison of the Mapletree/SugarMaple headphone amplifiers

Ear+ HD Super II  Headphone Amplifier

Customer feedback 

The use of  6BQ5/EL84 output tubes in the Ear+ HD250 was popular with customers who aprriciated its wide availability. Like the HD250, the HD Super II  utilizes the EL84 with triode connection in cathode follower mode (as is the 12B4A in the Ear+ HD). The 12AX7/5751 drivers are configured in SRPP topology. The power supply is constructed on a separate chassis to obtain the lowest possible noise floor and to minimize heat buildup in the main amplifier chassis, thus increasing component life expectancy. Both units are a compact 5" wide. Appearance is distinctive with brushed aluminum and chrome trim.  Wood side panels are not available as both chassis have ventilation holes along the sides. The two chassis can be stacked, positioned side by side or even located on different shelves. A 1 ft power interconnect cable is supplied; longer cables can be requested. Available with 240 VAC wiring at no extra cost.

provides three inputs and a passive output.

Bent Audio motorized Alps potentiometer or DACT stepped attenuator options.
Provides 4 inputs, source output, and passive preamp output. Please inquire about price and package options.

Ear+ HD Headphone Amplifier

"Now I have to listen to all my CDs all over again. I have a decent stereo system but with the Ear+ it sounds like a $20,000 setup".

Customer feedback

• Outstanding performance with a wide range of headphone impedances and drive requirements.
• 2 x 12B4A NOS and 1 x 5751/12AX7/ECC83 tubes.
• High and low impedance headhone jacks.
• Premium passive components include Panasonic polypropylene output capacitors and Alps volume control.
• Ultra high-speed rectifier diodes.
• Line output for use as a passive preamp.
• Dual inputs for easy patching into system.

• Available with red/black/white/yellow/blue/green chassis and/or brushed aluminum front panel.
• Solid oak side panels finished in ebony or natural.
• Dimensions: 7.5" x 12" footprint x 5" tall
• Weight: 8 lb

SugarMaple OD300 Headphone Amplifier

This is the first product developed by Mapletree Audio Design Associate, Dr. Al Freundorfer, under the new SugarMaple banner. The OD300 (Octal Duo) Headphone Amplifier employs an all-octal tube lineup including a 6080 (6AS7G equivalent) output and a 6SL7GT triode driver stage. Polypropylene output caps are standard and circuit refinements ensure a perfectly flat frequency response from 20 Hz to 20000 kHz. The high output power (over 1 W into 16 Ohms!) and low driving impedance of the 6AS7G easily handle any headphone sensitivity and impedance characteristic. For more details and complete specifications, you can download the User's Manual.

"The OD300 sounds great after settling in and combines musical dynamism with a lovely euphonic quality."

SugarMaple Sidewinder Headphone Amplifier

The latest take on the Ear+ HD theme features ultra-low output impedance and ample opportunity for tube rolling with new and NOS 6DJ8 and 12AX7 tubes and variants. For more details, download the User's Manual.

New! A comparison of the Mapletree/SugarMaple headphone amplifiers


Line 2B SE Line Preamplifier                   New! Review of Line 2B SE by Tim Smith at wall of sound.

Customer feedback

• Premium passive components include polypropylene film coupling capacitors and Alps volume control.
• Optimized circuitry for lowest distortion and noise.
• 3 inputs, 2 outputs, volume and balance control.
• 2 x 12SN7GT with switch for 6SN7GT tubes.
• Separate PS 2 power supply (with 6X5GT tube/fast diode hybrid rectification) included.

Also available—Line 2B HT with Home Theater bypass. The source input switch is modified to select Line1, Line2, or HT. In HT mode, Line2 (front channels) is routed to the output completely isolated from the preamp circuitry (preamp can be powered off).

New! RM 1 Remote Control unit for Line 2B preamplifier

A motorized Alps potentiometer or DACT stepped attenuator is now available for use with the Line 2B SE preamplifier. It provides three manually switched inputs plus the remote volume control with handset. The RM 1 output feeds one of the inputs of the Line 2B, leaving two additional inputs independent of the remote volume control setting. The Line 2B volume control remains available and the RM 1 control may be manually adjusted. Power for the RM 1 is available from the Line 2B with adapter cable supplied. The Line 2B shown below has been modified to provide a separate power output for the RM 1. The PS 2 power supply feeds the Line 2B as usual.


 Alternative styling for Line 2B/PS 2/Ultra 4B/LR 1/RM 1. If wood side panels aren't your first choice, consider an anodized aluminum front panel as shown her for a   Line 2B/PS 2. Black chassis only.

Ultra 4B SE Phono/Line Preamplifier

Customer feedback

Shown above in Cobalt Blue/below in sage green


• Premium passive components include
polypropylene film coupling capacitors and Alps volume control.
• 48 dB phono gain, two 18 dB line inputs, two line outputs.
• Volume and Balance controls.
• 2 x 12SN7GT (switchable for 6SN7GT) and 2 x 12SC7.
• Separate PS 2 power supply included.

Phono 3
Phono Preamplifier

For a number of years, customers have asked about a phono preamplifier that embodies just the phono stage of the Ultra 4. The issue was always that the Ultra 4 was really a phono preamp with line inputs, so there was little price or sonic advantage in going to a dedicated phono version of the Ultra 4 by omitting the volume/balance controls and source selector switch. The phono gain of the Ultra 4 is around 48 dB which is suitable for MM cartridges driving a typical tube or solid-state power amplifier. The new Phono 3 preamplifier incorporates the low-level gain and equalization stages of the Ultra 4 without the output buffer and with around 10 dB less gain. Thus, it is suited to drive the line input of a preamp or integrated amplifier with at least 5-10 dB of additional gain. The Phono 3 output has a driving impedance of around 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. Like the other Mapletree preamps, the Phono 3 is designed to use a separate power supply. Normally, this is the PSX unit that powers the L2X line preamp. However, the new PS 2a power supply can be ordered if sharing the power supply with the Line 2B preamp is desired. For those customers who have a Line 2 preamp and wish to add phono capability, existing PS 2 power supplies can be modified to PS 2a configuration at a nominal cost. Two switched phono inputs are provided, which can be ordered with custom loading specs. A power switch on the rear panel allows powering down the Phono 3 when just the Line 2 preamp is needed in a shared PS2a setup. Details and full specifications can be viewed by downloading the User's Manual from the "Users Manuals" page.

SugarMaple BB (Black Buff) Line Level Buffer Stage

You can now sweeten the sonics of your DAC or other digital source with the Black Buff  line stage. It features unity gain, 100K input impedance, <500 Ohms output impedance, and includes  a volume control and heater voltage switch for use of either a 6SN7GT or 12SN7GT tube (supplied). Tube heater glow is visible through opening in chassis. Download the User's Manual  for complete specs.


Dr. P spins some 78s on his mini system. Photo by Christian Keresztes
For more information or to place an order, please telephone or email Lloyd Peppard at
(613) 387-3830

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

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