Allnic/ZL Technologies L-7000

Immerse yourself in the original recorded space. The L-7000 is a single gain stage, transformer coupled, remote controlled line stage pre-amplifier. It uses the DHT 300B as a voltage regulator.

• DHT 300B as a series voltage regulator
• Single gain stage
• True Dual Mono design
• 41-step Silver Contact Constant Impedance attenuator

The 300B has justly won the reputation for being a superb output tube in single-ended amplifiers. But it will take some rethinking to imagine this great tube in a non-audio role. The benefit the 300B brings to as a voltage regulator is its ability to pass a fair amount of current at low cathode-to-plate voltages, the result of having a low Rp.

The L-7000 offers world class, holographic sound-staging combined with incredible resolution, clarity, micro-dynamics, and drive. Instrument and vocal tone and timbre are lifelike; placement of instruments and bodies in three dimensions startling, life-size, and addictive. The L-7000 has no voice of its own. It is silent, except for the music emanating from the blackest of backgrounds. The outstanding sonic quality is matched by the simple elegance, flexibility and ergonomic functionality of the casework and connection options. Few pre-amplifiers can compete. The L-7000 is, simply, a revelation.

The L-7000 is Allnic Audio’s reference line stage pre-amplifier. Like all Allnic Audio products, it uses permalloy (iron and nickel alloy) for its transformer cores. Allnic is grateful to Mr. G.W. Elmen of We stern Electric for inventing permalloy for transformer core use, and in so doing, providing an enormous service to recorded music listeners everywhere.

• DHT 300B as a series voltage regulator. The benefit the 300B brings to a voltage regulator is its ability to pass a fair amount of current at low cathode-to-plate resistance, the result of having a low voltage drop.

• True Dual-Mono design. Each of the two channels operates completely independent of the other. The chassis, attenuator control and the AC power connection are the only parts of this pre-amplifier that both channels share.

• Single gain stage. A single gain stage circuit uses only one tube for amplification (“gain”). This reproduces a purer, more detailed, more spacious and more dynamic sound than multiple gain stages.

• Line output transformer coupling. The L-7000 is “transformer coupled”. In tube amp circuitry, there are two coupling methods; one is capacitor coupling and the other is transformer coupling. Capacitor coupling is the traditional, low cost method. It is somewhat stable but transfers only voltage, not wattage (i.e., not real energy). With transformer coupling, about 90% of real wattage is transferred (there is still a transformer loss of about 10% of wattage, while voltage is not affected).

• In-house transformer manufacturing and transformer/tube matching. While transformer coupling is superior to capacitor coupling, all the advantages of transformer coupling depend on the quality of the transformer and on the choice of tubes. Allnic Audio manufactures its own transformers and uses what it views to be the best core material, permalloy. Allnic Audio’s unprecedented, wide (16 Hz ~ 50 kHz, -3db), low distortion, and ultra-flexible (up to 20 kHz square wave response) output transformer helps Allnic Audio to realize the ideal transformer coupled pre-amplifier. Of course, gain tubes are also carefully selected for three critical factors for function with the permalloy output transformers: high gm, low internal resistance and high mu.

• Power supply circuit with under 1% voltage regulation. The voltage regulation of the transformer is the percentage change in the output voltage from no-load to full-load. To get the best performance out of your transformer, you need the lowest possible voltage regulation. The voltage regulation of Allnic’s power supply circuit is under 1%. It yields an improved power transfer and lower regulation factor, resulting in increased current speed and better dynamics.

• Constant and low output impedance. One of the benefits of transformer coupling is that it facilitates constant low output impedance. Low output impedance is critical to the design of a good pre-amplifier. The L-7000 has a 150ohm (150Ω) constant output impedance at all frequencies. In capacitor coupling (C-R coupling), a “cathode follower circuit” is usually used to lower output impedance. Unfortunately, this method of lowering output impedance is accompanied by high distortion and has an “L” shaped output impedance curve. Please compare the two graphs below, especially for low frequency response. Allnic’s (left), other’s (right)

Allnic Audio’s Technology

Soft-start Circuitry

Allnic uses soft start circuitry that, after sufficient warm-up only, provides the high voltage supply to the plate of each tube. This protective design results in prolonged tube life and fewer and less frequent issues with tube performance.

Permalloy output transformers

Allnic uses very large permalloy (Nickel/FeSi) core output transformers. This provides for higher inductance with fewer windings than other designs can provide and results in the great benefit of an extremely wide range of output frequencies.

Line output transformer coupling

In tube amp circuitry, there are two coupling methods; one is capacitor coupling and the other is transformer coupling. Capacitor coupling is the traditional, low-cost method. It is somewhat stable but transfers only voltage, not wattage (i.e., not real energy). With transformer coupling, about 90% of real wattage is transferred (there is still a transformer loss of about 10% of wattage–voltage is not affected). Transformer coupling is superior to capacitor coupling. However, all the advantages of transformer coupling depend on the quality of the transformer and on the choice of tubes. Allnic Audio manufactures its own transformers and uses what it views to be the best core material, permalloy. Allnic Audio’s unprecedented, wide (16Hz ~ 75kHz,-3db), low distortion, and ultra-flexible(up to 20kHz square wave response) output transformer helps Allnic Audio to realize the ideal transformer coupled amplifier. Of course, gain tubes are also carefully selected for three critical factors for function with the permalloy output transformers: high gm, low internal resistance and high mu.

Beautiful 20kHz square wave response

We can show you how beautifully a 20kHz square wave response is reproduced.

New vacuum tube damping technology

Allnic Audio’s patented “Absorb GEL tube damper” technology prevents harmful vibrations from reaching the signal/gain tubes and, therefore, prevents micro-phonic noise propagation in the tubes. The Allnic Audio Absorb Gel damper technology effectively solves a problem that plagues most tube amplification systems. Provided other tube components do not introduce micro-phonic noise into your system, with the Absorb Gel damping system, you will enjoy a degree of transparent sound that will surprise and please you.

Full engagement output transformers

Conventional output transformers use pre-set secondary windings to accommodate 4, 8 and 16-ohm loudspeaker loads. However, these conventional transformers utilize only one secondary winding at a time, while the other secondary windings remain “idle”. This approach has two adverse effects. First, the output transformers are not working at their maximum efficiency, reducing their output relative to their potential. Second, the “idle” windings are not actually “idle”; they are subject to parasitic oscillations, producing their own “signal”. This undesirable electrical information is additive to the transformer’s output, distorting the amplified signal going to the loudspeaker. Allnic’s “Full Engagement” transformers address these issues by having 4 independent, secondary windings which are always fully connected, never “idled”. This means that all secondary windings are always connected to your loudspeakers, regardless of which output switch position.

Powerful driving circuitry

Allnic believes in the importance of using high-quality, low noise and powerful driving circuitry in all its amplifying devices. Therefore, for example, in the M-3000 mk2, we employ the E282F tube (E55L for M-5000) in triode mode as the second stage driver tube, with a load of about 6 k ohms, and using 20 mA of current. The listener can easily hear and even “feel” the differences between this design and other, more conventional, ones. Please imagine, as you listen to the M-3000 mk2, its sound compared to the sound of an amplifier with conventional 12AU7 or 12BH7’s used as drivers, with a load of about 47 k ohm, and using 2 to 3 mA of current.

Analogue power tube current monitors

In order to provide constant current (bias) monitoring for the power tubes, Allnic uses a separate analogue current meter for each tube. The meters make it exceptionally easy to see the status of each tube at any time and to respond immediately to any variation in bias by use of the bias control knob for the relevant tube. The meters offer a simple, unambiguous indication of each tube’s status compared to conventional LED bias monitors.