Review: ALLNIC AUDIO L-10,000 OTL/OCL Linestage Preamplifier

Greetings! It has been some time since I have written any review or contributed to any forum. Now I have come across something that is worth an audition in any system. The NEW Allnic L-10,000 OTL/OCL Linestage. This is my first experience with a Transformer-less and Capacitor-less component.

While not by any means economical, to realize the true potential of the benefits associated with this circuitry I had to reconfigure some aspects of my system.  

The Allnic L10,000 OTL/OCL contains a more complex wiring system than the new Allnic L8000 DHT thus involving a circuit board and necessitating a somewhat higher price point. The clarity presented with this linestage demonstrates how a preamp can really be the limiting (read detrimental) component in the signal pathway. The L10,000 is single ended designed circuit, meaning in order to run balanced outputs, there exists a small insulation transformer, which separates the ground from the cold signal. The output from this linestange is 20V, so even when you need to run long distances - for me 31 feet, a well shielded unbalanced cable performs without issue. This level of potential also has a secondary benefit for low watt single stage class A amplifiers that only boost an already strong and very clean signal. This gives much greater headroom and overall dynamics.  

This preamp also has a low 200 Ohm impedance output and therefore plays well with most if not all amplifiers on the market.

By my estimation, the qualities that set this unit apart from any predecessor becomes somewhat lost when balanced outputs are used. This necessitated the selling of my 10 meters of balanced and very expensive Antipodes Reference cable. This finding is somewhat surprising to me. Allnic is infamous for their high grade and well-designed nickel alloy transformers. After my Allinc L4000, I moved to a passive transformer for years, the Final Drives by Empirical Audio. These $3000 passive transformers were a stellar price-to-value item. Auditioning may preamps in the interim, only the Direct Heated Triode, Allnic L5000DHT would provide better sound but at a significant price penalty.  

Trying to eliminate any confounding influences, I inquired with my source component manufacturer, Collin Shin of Waversa Systems. He stated the output stages are of comparable sonic qualities. I then used the same brand and model cable, Antipodes Reference. However, the balanced XLR cable was 3 meter and the unbalanced RCA cable was 1.5 meter. The single-ended input to the linestage improves sound significantly—much more open, airy, with a deep soundstage. This difference in clarity is not subtle, which demonstrates to me that ideally, equipment that are synergistic are ones of the same circuit topography. In other words, use single-ended circuit design components with single-ended cabling throughout the signal path.  

Even with the standard tubes, there is no warm-up required. What this pre-amp offers is bar none the greatest improvement to my system since this journey started in 2012, L4000 to L5000 DHT to L10,000. This upgrade tops any dac, and component upgrade. The clarity and presentation are on a level that every family member took notice.  

Regarding tube influence in signal path: 12AU7>>300b>>>6AN8. The latter had only one manufacturer and supply is plentiful. Another advantage here is 12AU7's are not expensive, with the rarest, coveted tube costing me $200 --but what a difference with RT 12AU7WA Black Plate. Oh my, super quiet, super refined, soooo delicious. This one does no wrong at all, period. These are pretty much neutral, with a lot of special thrown in: Air, density, energy, dimension, and super wet sounding. To me: Deep, soulful, sultry, passionate.

I switched from Russian stock tubes to Kron 300b and did not observe much gain. However, I do notice a deeper and tighter bass. Seems for my L10,000 the 300b tubes have limited benefit. I have interest in the anticipated release of Western Electric 300b re-issue first quarter 2019. I know in this linestage David Beetles was not super impressed with Takatsuki TA300b, which is a proven spectacular tube. I speculate this may be more to do with the circuit design of the L10,000. Because of the wide variation of presentation, the adventure in tube rolling may pay dividends vesting in the cheaper 12au7.  

From my personal life story, I can never pinpoint the moment I found love, yet I certainly noticed the moment it ends. Once my system had great emotion but then was lost for many years. This left me somewhat frustrated and disenchanted in the hobby. It was one unexpected day I received a phone call from David Beetles of Hammertone excited about his ‘holy shit’ moment and unlike finding love, I too shared this moment. Finally, there exists a tonality and subtleties with deep intricate layering presenting great emotion long missed and in reality never experienced to date! With great appreciation of Kang Su and his team at Allnic Audio Labs, I agree this unit is a keeper!

Current System:

99 dB Daedalus Zeus replaced 97 dB Ambience Reference 1600's Neodymium Ribbon.
Allnic L-10000 OTL/OCL linestage replaced Allnic L-5000 DHT
Allnic A-6000 60 watt single ended quad parallel 300b Monoblocks with Emission Labs 300bXLS.
Waversa Systems WCORE ROON server and DAC3. Pending arrival of New Waversa flagship dac
Antipodes Reference XLR/RCA/Speaker unshielded and Allnic Zu7r RCA shielded.
Power cables: Wireworld Pure silver OCC to Allnic ZA5000. Latter is recommended for both high current AND digital applications, over the ZA3000.
Torus 75 Amp Wall mount isolation transformer
Audience Adept Response 12 TSSD – run digital equipment.

David Beetles:  Canada
Albert Porter:

From the Manufacturer:

L-10000 OTL/OCL Preamplifier

The L-10000 Preamplifier is a Direct Coupled OTL/OCL Tube Preamplifier.

OTL/OCL means “Output Transformer-Less” and “Output Capacitor-Less”.

In an OTL/OCL preamplifier, there is no coupling device between the preamplifier and the power amplifier, that is, the preamplifier’s final output tubes are directly connected to the power amplifier. Normally, an Output Capacitor or Output Transformer for separating AC music signal from the DC operating potential; if this is not done, the latter will destroy the power amplifier or loudspeakers. But these two types of coupling devices are effectively obstacles to transmission that add their own character (color), increase distortion, and consume small signals according to physical efficiency theory. In addition, they limit signal dynamics.

Because of all these adverse effects, OTL/OCL has been considered the best solution for amplifiers in order to maintain signal purity.
* Removing these two coupling devices from the signal path, gives the best results.
* No coloration is added to the musical signal.
* Extremely detailed expression, natural harmonics and subtle musical decay are achieved.
* There is the lowest distortion possible due to the absence of coupling parts.
* The widest musical dynamics are attained.
* Some circuit experts might worry about DC potential in the music signal, but there is no need to worry. Allnic uses a “floating power supply circuit” which prevents the creation of any DC potential in the first place.
*The OTL/OCL circuit is basically SEPP, “Single Ended Push Pull”, so we need a “cancellation circuit”, which adjusts the balance of signal between the upper and lower power output tubes’ input grids.

Newly developed 61 STEP CONSTANT IMPEDANCE BRIDGED TYPE ATTENUATOR, world premier, is installed inside, which contributes to L-10000’s different dimensional sound.

Allnic uses the most sophisticated “Active Balanced Positive and Negative Feedback Circuit”, in which a 6AN8 pentode perfectly controls all the circuit’s entire operation with extremely low distortion and the greatest speed.

• Input Impedance: 10 kohms(RCA, XLR)
• Frequency Range: 5 Hz to 100 kHz
• Voltage gain: +18dB
• THD( 1kHz, 1V RMS) : less 0.03%
• S/N ratio: -90dB
• Maximum Output: 20V RMS(non-clipping)
• Output Impedance: 200 ohms
• Power consumption: 120W (230V 50/60 Hz)
• Tubes: 300B x 4, 6AN8 x 2, 12AU7 x 2
• Fuse: 3A/230v, 5A/120V
• Dimension: 430mm x 450mm x 280mm WDH
• Weight: 22kg/net