MODEL L72P-1
Your Search for the German Console Preamp Sound Ends Here

500 series channel of the most accurate sounding V72-style gain available today

The Locomotive L72P gives you the solid lows, thick & creamy mids, and smooth top end - just like the original

Inspired by the console amplifiers built for the German Radio Network decades ago, the Locomotive L72P delivers the sound and character of the original V72 modules, all with the modern options and flexibility today's engineers need. Countless hours were spent making sure every aspect of the L72P amplifier lived up to its vintage inspiration.

From house-wound transformers and plate chokes to more affordable and easy-to-find tubes, we designed the L72P with two things in mind: performance and ease of use well into the future.

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Accurate vintage specifications with modern flexibility

Authentic Reproduction of Transformers and Plate Choke

Accurate Low Distortion

Up to 54 dB of gain in 4 dB Steps (Vintage Module - 34 dB)

Dedicated Line Input XLRs

Numerous Dual Triode Tube Options (see details here)

Output Attenuation Control
in 2 dB Steps

$1099 PREORDER PRICE
PREORDER ENDS JUNE 20
REG. $1299

NEW L72P-1 PREORDERS START SHIPPING IN LATE JUNE. PREORDERS ARE FIRST COME - FIRST SERVED.

WORLDWIDE SHIPPING EXCEPTIONS

Authentic reproductions of the input transformer, output transformer, and plate choke

By far, the most important part of the vintage V72 sound is the combination of input and output transformers, as well as the plate choke. Given how low the harmonic distortion is within the amplifier, most of the coloration we hear comes from these three components.

Our house-wound transformers will guarantee you get a punchy, solid low end, thick and creamy mids, and smooth highs!

More detail here

Coils, Coils, Coils!

By zeroing in on what gives the original modules their unique sound, it was decided that the input transformer, output transformer, and plate choke should be the main focus. The audio path with tubes, capacitors, and resistors is the easy part. But, off-the-shelf transformers just don't have the response needed to match the original modules' qualities. We took it upon ourselves to develop modern recreations of these three vintage components. The expense and time required to make these transformers is tremendous, but it's the only way to truly achieve the sound we are after.

Studying the original build sheets and testing our vintage modules' transformers and chokes, we wound coil after coil, failing over and over until we finally wound exact matches to the originals!

We tested inductance at different frequencies, primary and secondary stray capacitance, interwinding capacitance, DC resistance, phase, square wave response, and frequency response until we nailed the exact specifications we were after.

From the six-chamber input to the three-chamber plate choke to the screened, multi-section output, the response of the L72P is exactly the same as that of its vintage inspiration.

See the full amplifier square wave response of the L72P compared to the original. (Vintage module (Blue) / L72P (Red) set to 34 dB gain)

Input Transformer

The original V72 modules developed for broadcast differed slightly to the “S” (Studio) version which was made popular years later by companies like Decca and EMI (Abbey Road). In short, the "S" input transformer version is just a touch flatter in the high frequencies when compared to the original non-“S” broadcast version. The difference is about 0.25 dB at 15 kHz and 0.5 dB at 20 kHz.
The stock L72P ships with the "S" configured input transformer. Both versions still give the amplifier that thick low-mid sound! If you prefer to upgrade to the "non-S" version of input transformer, you may upgrade when you add-to-cart. All input transformer mu-metal shielding cans are marked on top to indicate the transformer's version.
We also have included a user-selectable jumper on the circuit board that alters the response of the input transformer by changing the input transformer "load resistance" from 400k ohms to 200k ohms. This was a common mod applied to the "S" configured modules.

The above frequency response shows the effect of different input transformers within the entire amplifier circuit. L72P is set at 34 dB gain.

L72P Input Transformer

(Mu-Metal shielding can not shown)

Inputs V72 vs L72P Blue - Both Reverse Wound 425k.BMP

Non-"S" Version

"S" Version with 400K ohm load resistance

"S" Version with 200K ohm load resistance

The above square wave response shows an original vintage V72 non-"S" input transformer (in yellow) and the L72P input transformer (in blue/green)

Plate Choke

The plate choke is just as important as both the input and output transformers in this circuit. It provides a high-impedance load for the output tube, allowing a larger output-level swing before distortion sets in. The V72 circuit uses a 3-chamber plate choke, which helps high-frequency response and lowers distortion within the amplifier as frequency rises. The L72P choke uses an expensive nickel core, just like the vintage Siemens modules we have modeled this unit after.

Output Transformer

The L72P output transformer was designed to replicate the vintage module's output transformer response. This transformer has 4 copper shields between the windings, which help maintain high-frequency response.

We wound about 12 prototype versions of this transformer before landing on the final design. The only difference between the 12 versions is how much tape was used between winding layers. These small changes dictate how the transformer responds, both to transients and overall phase and frequency.

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Quiet and Reliable Tube Options

After the transformers, tubes are the next main focal point in the L72P design. A major deviation from the original vintage design was necessary due to the shortage of quiet, high-quality EF86 pentode tubes available today.

Instead of using two EF86 or EF804 pentode tubes, as the vintage design dictated, we designed the L72P to use two dual triode tubes, each in a "cascode" arrangement. This configuration is a special way to replicate the response of pentode tubes, without the inherent issues of noise, microphonics, scarcity, and expense.

We fine-tuned the L72P to use 6922/E88CC tubes to match the original module's response. The user can also use other common tubes, such as 12AU7 dual triodes, as a substitute. Read more

TRANSFORMERS

House-wound plate choke, input and output transformers just like the vintage modules

TUBES

Two 6922/E88CC tubes (in cascode arrangement) amplify the signal with 54 dB of max gain

OUTPUT CONTROL

A 5-position rotary output attenuator allows the user to adjust total final output level in 2 dB increments

PAD OPTIONS

Standard 20 dB pad and 34 dB pad for line level sources.

SEE ALL FEATURES AND SPECS

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L72P INSPIRATION

Remaking vintage circuits requires time and patience to achieve the perfect balance. The L72P produces the warm, organic, and characterful sound of its vintage inspiration, beautifully complementing the sounds of the Locomotive 86B and 40AM.

L72P users can expect their hardware to perform and sound just like the vintage V72 units. Solid bottom end, thick and creamy mids, low harmonic distortion, and clear, never-harsh top end are among the greatest attributes to this unit. Front panel flexibility, a variety of tubes options, and dedicated line input mode will up your mixing game!

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The following sound samples show the difference between 3 different Locomotive preamps when sent the same prerecorded line-level audio.

Each preamp has been set to accept a line-level input. The 40AM was set at (HIGH) LINE unless otherwise noted on sound file.

LIFETIME WARRANTY

As an audio engineer, we know you want to use the best tools to shape your sound. And if you are going to spend money on gear, you deserve hardware that's always in tip-top shape. You shouldn't have to worry about when something goes wrong. Rest assured, we guarantee the gear we build by backing it with a lifetime warranty.

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* V72 is a registered trademark of TAB-Funkenwerk. Locomotive Audio is not affiliated with or endorsed by this company. The L72P is designed and manufactured by Locomotive Audio. It is a remake of the original V72 circuit, which was produced in the 1950s and 1960s.

SUPPORT & WARRANTY