With the Z40+ Integrated Amplifier, Linear Tube Audio (LTA) promises—”beautiful tube tone with the clarity of solid state”—from 51 Watts (into 4 Ohms) of push-pull, class A/B output transformer-less ZOTL power per channel.
Being output transformer-less also means the Z40+ weighs a heck of lot less than similarly powerful transformer-endowed amps, which is music to my back. The new “+” version of the Z40 offers a number of upgrades including 100,000µF of additional capacitor storage, Audio Note resistors, Subwoofer Output, and an updated Volume Control w/ Adjustable Gain & “Hi-Res” Settings.
The review unit includes the optional MM/MC phono input which joins the RCA and XLR inputs, Tape Monitor (In/Out), Sub Out, IEC inlet, power switch, and single pair of Cardas speaker binding posts on the unit’s back side.
Four Gold Lion KT77s peak through the Z40+’s top plate (NOS Mullard EL34s are also available), while pairs of 12AU7s, 12AX7s, and 12AU7s hide inside.
A pair of headphone jacks (Hi/Lo) join the brass touch sensitive buttons on the Z40+ front panel. Fern & Roby designed the Z40+’s understatedly handsome chassis while David Berning’s patented ZOTL technology and preamp design reside within.
LTA Z40+ Integrated Amplifier
Price: from $7650
Company Website: Linear Tube Audio
Inputs: 4 single-ended Cardas RCA stereo, 1 balanced input using two 3-pin XLRs
Speaker Output: 4 Cardas speaker binding posts
Headphone Outputs: Low: 220mW per channel @ 32 ohms, High: 2.6W per channel @ 32 ohms
Tape Monitor: 1 stereo tape monitor out, 1 stereo tape monitor in
Subwoofer Output: Stereo subwoofer output (Mono option available upon request)
Front Panel Controls: 7 brass touch switches (power, input, tape monitor, up, down, menu/select, back), volume control, and headphone speaker switch
Remote Control: All front panel functions using paired Apple TV Remote
Volume Control: 100 stepped attenuator (smallest step 1/1000th of total value) using Vishay Dale 1% precision resistors
Output impedance: 1.2 ohms
Input impedance: 47k
100V / 120V / 240V operation: Auto-switching
Hum and noise: 94dB below full output (measured at 20Hz-20kHz)
Power output with 4-ohm load: 51W, 0.5% THD
Power output with 8-ohm load: 46W, 0.5% THD
Frequency response (8-ohm load): 6Hz to 60kHz, +0, -.5dB
Amplifier class: Push-pull Class AB
Size: 17 inches wide, 5 1/8 inches tall, 18 inches deep (including connectors)
Net weight: Amplifier: 18 lbs./8.2 kg
Finish: Aluminum case
Tube complement: 2x 12AU7 preamp, 2x 12AX7, 2x 12AU7, 4x KT77
Home Theater Function can select any input for fixed volume
Display: 16 Levels of brightness and programmable 7-second time out
MM/MC Phono Stage:
Inputs: MM or MC
MM Gain: 46 db fixed
MC gain: 10db/20db additional (56 db total or 66 db. selectable by jumpers)
MM loading: 47K ohms
MC loading: 10, 20, 30, 50, 100, 200, 470 ohms selectable by dipswitch
100pf, 220pf, 330pf selectable by dipswitch