What does the ZOTL10 Mk II amplifier sound like?

Here is how a selection of reviewers have described the ZOTL10 Mk II amp:

Part-Time Audiophile Review:

While it’s not exactly the “classic” sounding vacuum tube amplifier in many respects, it does seem to preserve those things that tubes do really well (think open, unfettered sound with highly natural harmonics) while minimizing their perceived shortcomings. This amplifier earns my accolades for its stunning sense of clarity, transparency, and precise spaciousness of sound.

Enjoy The Music Review:

I am smitten with the ZOTL10 MK II. Its brings out the best in any music you play through it. Rock, jazz, classical, pop – it doesn't matter. What made it so difficult to review this amp is the reviewer part of my brain would keep shutting off and I would just start listening to the music. I can't think of any better compliment than that.

The Audio Beatnik Review:

The ZOTL10 Mk.II also gave me a very realistic musical presentation… It plays music with wonderful harmonics and richness but with musically quick transience and very nice bass control. Mentioning the bass, it was able to carry the music with a really good rhythmic drive. The bass was also very well defined but not overly tight, and there wasn’t the least bit of “one-note bass.” There was also a very natural air around and within most bass instruments.

The top end was smooth and very extended. String and woodwind overtones were played beautifully. I was particularly impressed with the air around reed instruments and with the bite of horn instruments. Another important job of the top end of an amp is to have enough detail to help place the instruments and voices as they should be on the soundstage. In this area, I was very happy. The soundstage and imaging were very well portrayed by the Mk.II.

What does the ZOTL Ultralinear amplifier sound like?

Here is how a selection of customers and reviewers have described the ZOTL Ultralinear amp:

Terry London’s 6moons.com review:

Think of the ZOTL Ultralinear amplifier as a world-class SET for its inner glow of gorgeous color/timbres plus the sense of aliveness and dynamics of a more powerful push/pull. This amplifier would be welcome in any system with standard speakers and listeners who prioritize beautiful tonality and timbres, first-rate imaging and the aliveness and 'speed' of live music.

~Audiogon User dodgealum

In my system the Ultralinear conveys the natural warmth of acoustic instruments and voices without editorializing. It is exceptionally clean, quick and dynamic yet completely uncolored and free of sonic artifacts. When you listen through this amp your focus will be squarely upon the music, not the means (transistors or tubes) by which it is being reproduced.

~ The Audio Beatnik Review

I’ll start by saying this is the best Class AB amplifier I have ever heard. The first thing I noticed was that the LTA Ultralinear was the quietest amp I have ever heard; not the quietest tube amp, but the quietest amp. I think this enabled me to hear some of its most captivating qualities; its incredible sense of pace and rhythm, explosive dynamics, and micro-dynamics. I found myself tapping my foot almost as often as I do when listening to live music. The amp is so unbelievably natural that it was hard to think about anything but the music, the glorious music.

Will the headphone output on the microZOTL Preamplifier work with my "hard to drive" / "hard to pair" headphones? (Sennheiser HD650, HiFiMAN HE1000, HE-6, HD800)

In some cases, such as the HiFiMAN HE-6, which has notably low sensitivity and thus requires several watts to power adequately, the microZOTL Preamplifier will give you a satisfyingly loud and full listening experience.

Since the unique circuit of LTA amps reacts very little to different impedances, it is mostly a matter of sensitivity when it comes to which headphones the microZOTL Preamplifier headphone output works well with.

Whether it can "drive my headphones" often just means "will I prefer how my headphones sound with this amp?" We've read many accounts of people thinking their HE1000 or HD650 has never sounded better than with their microZOTL Preamp. I've also read one or two accounts of people saying the opposite.

We don't know what you like, but we do know that we've read far more mentions of the microZOTL Preamplifier sounding good with all kinds of headphones than not.

How do I change my LPS+ Linear Power Supply to work with 110V or 220V electricity?

Switching the LPS+ Linear Power Supply to work with 110V or 220V electricity is a simple process.

Look where the AC cord plugs in. You can see the voltage it is set to thru the window.

  1. Carefully pry the little door open from above the red window.

  2. Carefully pry the red fuse block out of the hole.

  3. Turn red fuse block over and reinsert.

  4. Close the door and it should say the proper voltage in the little red window.

  5. You're done.

Here are photos to help you.

Do LTA amplifiers have good bass?

Yes.

Many of our customers describe the bass as “thunderous.” Steve Guttenberg of CNET described the bass of one of our products this way:

Bass depth and definition were well-ordered... There's no muddiness down there of the sort I get from a lot of tube amps.

From a technical perspective, ZOTL amps have a linear frequency response below 10hz.

To put that number into perspective, the lowest most full-range speakers go to is about 20hz, with most being closer to 28-32hz. Even REL, arguably the world’s top subwoofer manufacturer, their flagship subwoofer goes down to 14hz.

So, whatever is in the music, our amps will be able to deliver.


Related FAQs

Can I use a subwoofer with the Z10 Integrated amplifier?

Yes, however, the Z10 Integrated amplifier doesn't have a dedicated output for a subwoofer. The interface to a subwoofer would be via the speaker outputs, which is a common and often recommended solution.

You will need a subwoofer with a "high-level" input, often called a "speaker-level" input, which again is pretty common.

This method of connecting a subwoofer is recommended over a dedicated subwoofer/preamp output because it ensures that your subwoofer and speakers are using the exact same signal.

Don’t take our word for it. REL, maker of some of the finest subwoofers in the world, recommends using this method for connecting their subwoofers to amps of all kinds:

Using the High Level input is always the best option. Using the High Level Input, instead of the Low Level Input, and connecting to the speaker output terminals of your amplifier is one of the unique secrets of REL’s success. When using the High Level input, your REL is fed the same signal that your main speakers are receiving. When connecting to the High Level input on the REL from the amplifier, you capture the sonic signature of your main system, including the tonal balance and timing cues of the entire electronics chain.


Related FAQs

Are ZOTL amplifiers different from other OTL amps?

OTL (Output Transformer-Less) amplifiers manufactured by other companies are a completely different technology than ZOTL amplifiers.

ZOTL technology involves a linear amplification process using a carrier frequency as well as not having a traditional audio output transformer, instead using air-core Impedance Converters.  

Noted pioneer of amplifier technology, Julius Futterman, has inspired many different amplifier designs over the years. Based on Futterman’s principles, other OTL amplifier designs incorporate two separate banks of parallel-connected tubes. The two banks are joined in series by connecting the effective cathode of one tube bank to the effective plate of the other tube bank, and driving the loudspeaker in a push-pull fashion directly from this junction point without a transformer. There are alternatives to Futterman’s principles that use low-impedance triodes, but the basic principles are the same: given a sufficient number of parallel-connected tubes in each bank, enough drive current can be obtained to drive the speaker.

The output impedance of other OTL amplifiers is nowhere near the actual speaker impedance.  In an OTL amplifier, a large amount of negative feedback is required to force the push and the pull to work together properly in order to provide sufficient damping for the speaker. Even with the lowest impedance triodes available, there is still a basic impedance mismatch between the tubes and the speaker in the OTL circuit. 

Traditional OTL technology requires a large number of power tubes which need to be driven hard to obtain the required output. This results in drastically reduced reliability and tube life and generating lots of heat.  Fans or additional room air-conditioning may be required. Power consumption is typically very high for OTL amplifiers, often exceeding one kilowatt for a stereo pair.

Why would you want to remove the output transformer from an amplifier?

Audio amplifier design engineers have long sought to eliminate audio output transformers because of the restrictions they impose on amp performance. Leakage inductance and interwinding capacitance limit the high-frequency response of transformers while core saturation and magnetizing current limit their low-frequency response. Transformer-core hysteresis causes specific distortions of non-symmetric and transient waveforms that are characteristic of musical reproduction. Audio output transformers simply cannot achieve the correct turns ratios as they only max out at 25:1 due to saturation and hysteresis effects. This leaves much to be desired, which creates and issue that needs to be resolved.

Enter the solution: ZOTL.

First, the audio signals “ride” a carrier frequency, on which they are amplified by the tubes (it is not a hybrid amplification design), then the carrier is removed by the Impedance Converters and the remaining audio is delivered to the speaker, similar to how a radio station and receiver work. This changes the impedance plane to match the impedance of the speaker, so the audio output transformer is no longer required to match the tube to the speaker. An Impedance Converter accomplishes this match up. This super linear amplification process allows the amplifier to have a flat frequency response from 8hz to 50Khz, which is nearly impossible with an output transformer.

However, the real advantage is in the transformer turns ratio. Output transformers are limited to a maximum of about 25 to 1 in turns ratio. This turns ratio does the matching between the tube output and the speaker. It turns out that the theoretically correct turns ratio for most tubes is typically 100 to 1 and even as high as 300 to 1. The ZOTL can use the impedance converter to effectively create the ideal turns ratio. The microZOTL has a 300 to 1 ratio and the ZOTL40 has around a 150 to 1 ratio. This results in the detail and accuracy of the sound.

Who is David Berning?

Considered to be one of the world’s foremost amplifier designers, David Berning is among the elite in his field.  A formally trained physicist, David’s unique perspective has invaluably colored every solution he’s designed for classic audio problems. 

After 20 years of designing and manufacturing tube amplifiers, David Berning turned the technology on its ear when he invented ZOTL (Zero hysteresis Output Transformer-Less) architecture in 1996. So radically different from anything around at the time, ZOTL was and still is considered the most significant improvement to tube amplifier technology since the 1960s.  

Even out of production, Berning’s ZOTL amplifiers regularly collect accolades from the world’s top audio reviewers and publications. His ZH-230 amplifier has received Absolute Sound Magazine’s "Editor’s Choice Award" every year since 2011. His Quadrature Z amplifier won HiFi+ magazine’s "Product of the Year" award in 2009. His 211/845 ZOTL amplifier was introduced by Hi Fi One at the 2014 Munich High End Audio Show.  Timeless examples of Berning’s audio genius, the ZH-270 and EA-2101 are still highly sought after by audiophiles everywhere.

David Berning plays an integral role in the development of LTA’s offerings. Currently these include LTA's reconfiguration of his original microZOTL personal headphone amp, the ZOTL10, a mid-to-high efficiency power amp, and the ZOTL40, David's latest ZOTL amplifier designed for LTA, which is in essence the successor to his own, much lauded, ZH-230.

Here’s what others in the industry have said about David Berning:

Herb Reichert in Stereophile:

I have admired David Berning since the 1970s, when I enjoyed his EA230 tube amplifier. The EA230 was a sonically well-balanced variation on the classic Williamson circuit (a push-pull amplifier, made with carefully designed output transformers and using global negative feedback), which sounded especially good with electrostatic speakers.

Rick Becker in Enjoy the Music:

Those of us who get out into the world have probably met people whom captivated us with their accomplishment or their persona. David Berning is such a person for me. His reputation preceded my encounter with any of his amplifiers by an uncertain number of years. But I'll never forget the first encounter with the ZH270.

Bolling Bryant in Audiogram:

If there ever was a genius in home audio it would be David Berning.

How do ZOTL amplifiers sound?

Many tube amplifiers have a sound described as "warm," "tubey," or "round".  This sound can be very nice to listen to. However, it is the output transformers that produce the "warmth" or the tone of the sound, and it is actually a type of distortion, though pleasant.

The downside is the detail of the music can be lost in the "warmth." There is no doubt that many people love the warmth of what they think is the tube, but is actually the transformer.

ZOTL amplifiers do not have the thicker, warm tone that many tube amplifiers have. They still have the liquidity and linearity of tubes, but without a transformer's tone.

ZOTL amplification achieves neutral accuracy without coloration. This achievement is supported both by listening and through measurement.

Switching immediately from other tube amplifiers (and solid-state amplifiers designed to be warmer) to a ZOTL amplifier can often feel like something has been lost. What is actually happening is more akin to adjusting the focus of a lens: an increase in clarity accompanies a reduction of haze. While haze can feel like "body" or "weight" that is no longer there, as you adjust to the ZOTL amplifier you realize you are hearing the more accurate weight and body of what you are listening to, and the consistency in performance over varying impedances will allow you to experience this accuracy throughout the frequency spectrum with many different speakers. 

ZOTL amplification's neutrality is also transparency. As source components increase in performance, ZOTL amps continue to reflect this, scaling up indefinitely.

Do you ever have demo or return units that you sell at a discount?

The short answer is: usually, no.

The slightly longer answer is that we have an extremely low return rate for our products. Any demo units are usually brought back to the shop and used for testing or continued use in our on-site reference system or at future audio shows, events, etc.

You’re welcome to contact us to inquire about what might be available, but just know that the answer will likely be that we have none.

What kind of tubes do you use in your amps?

The below chart lists the type and number of tubes used in each of our amps.

Linear Tube Audio sources the best tubes we can find for use in our production units, tested and curated to provide the best experience for our customers. When you buy an LTA amplifier, know that it will come supplied with the highest quality, premium tubes we can find.

LTA Amplifier Model

Tubes Used

Input

Output

microZOTL Preamplifier

12AT7 (2x)

12SN7 (2x)

MZ2

12AT7 (2x)

6SN7 or 12SN7 (2x)

MZ3

12AT7 (2x)

12SN7 (2x)

Z10 Integrated

12AT7 (2x)

12AU7 (4x)

EL84 (4x)

Z10e

12AT7 (2x)

12AU7 (4x)

EL84 (4x)

ZOTL10 Mk II

12AT7 (2x)

12AU7 (4x)

EL84 (4x)

ZOTL Ultralinear

12AU7 (2x)

12AX7 (2x)

16JN6 (4x)

ZOTL40 Reference

12AU7 (2x)

12AX7 (2x)

EL34 (4x)

Tubes can be a Pandora’s Box or a rabbit hole, depending on your outlook. For many, the opportunity to alter and improve the sound of their amp by tube rolling, is one of the joys of owning a tube amp.

If this describes you, we encourage you to explore different tubes, and feel free to contact us with any questions you may have along the way.


Related FAQs

Will your amps pair well with my low / high sensitivity speakers?

Linear Tube Audio makes amplifiers that range in power output from 1-watt (yes, you read that correctly) to over 50 watts per channel, which is quite a range.

To help guide you, below is a chart listing all of our amps and our recommendations for speaker sensitivity pairing.

It’s important to note that LTA amplifier owners have found great enjoyment using their amps with a variety of speakers outside of the below ranges. The below are guidelines, not rules.

LTA Amplifier Model

Listening environment + Speaker sensitivity recommendations

Critical Listening

Smaller rooms / lower volumes

MZ2

105db+

97db+

MZ3

105db+

97db+

Z10 Integrated

90db+

88db+

Z10e

90db+

88db+

ZOTL10 Mk II

90db+

88db+

ZOTL Ultralinear

88db+

85db +

ZOTL40 Reference

85db+

80db+

Some of the wide variety of speakers that have been heard to work well with ZOTL amplification: Quad 57s, Maggie Minis, Tekton Design, Fern & Roby, Voxativ, Janszen, Decware, Klipsch, Silverline, Spatial, DeVore, Daedalus, Zu, Ryan, Living Voice, Omega, and many others.

If you have questions about your specific speakers, chances are someone we know has tried them. Don’t hesitate to reach out with questions about your specific setup.

Also, don’t forget we have a 14-day no-questions-asked return policy.


Related FAQs

The MZ3 is a 1-watt speaker amp... Will it work with my speakers?

The answer to this question all depends on how sensitive your speakers are, what kind of listening you plan to do, and how big your room is.

In any case, you will need speakers that are highly sensitive. Our speaker sensitivity recommendations for the MZ3 are:

  • Critical listening environments: 105db sensitivity and above

  • Smaller rooms / lower volume levels / non-critical listening: 97db sensitivity and above

Horn-loaded speakers, such as Klipschorns, are really your only option at the 105db level. We know from experience and through many customer testimonials, that the MZ3 and horn-loaded speakers make a wonderful combination.

If you have horn-loaded speakers, you owe it to yourself to audition an MZ3 or one of our other lower-wattage amps, such as the ZOTL10 Mk II power amplifier, Z10 Integrated amplifier, or even the ZOTL Ultralinear amplifier.

If you have questions about your specific speakers, chances are someone we know has tried them. Don’t hesitate to contact us with questions about your specific setup.

Also, don’t forget we have a 14-day no-questions-asked return policy.


Related Products

microZOTL MZ3 Headphone Amp / Preamp / Integrated Amp

Small and mighty. The highest expression of the patented microZOTL technology as a headphone amplifier, a preamplifier, and integrated amplifier in a desktop-sized package.

microZOTL MZ2 Headphone Amp / Preamp / 1-watt Speaker Amp

The second generation of the product that started LTA, the microZOTL MZ2 contains years of product development in one compact chassis. Built on the 6SN7 tube, the MZ2 remains the reference introduction to the unique ZOTL circuit.

Z10 Integrated Amplifier

For those who demand the best, but want to keep things simple. The Z10 Integrated amplifier delivers the magic, realism, and 3D soundstage of our patented ZOTL technology, all in one (gorgeous) box.

ZOTL Ultralinear Amplifier

The ZOTL Ultralinear is the latest amplifier design by David Berning: the first ultralinear amplifier not limited by traditional output transformers.


Related FAQs

Do you sell your amps in stores? / How can I listen to one of your amps?

In order to keep the cost of our amps as low as possible for our customers, we do not sell our amps through dealers or resellers. We only sell direct to our customers.

While this does make it slightly more difficult to audition our amps, we do have a 14-day return policy that allows you to audition any of our amps in your home.

After purchasing an amplifier, you have 14 days after you've received it to return an amp for any reason and receive a full refund for the purchase price, assuming the unit is returned in the same condition we sent it.

This allows you to listen to any of our amps in the familiar confines of your home, with the other components you are familiar with. This is a much better way to evaluate any new component than in an unfamiliar showroom with unfamiliar components.

That said, if you are near Washington, DC, we invite you to our workshop to see where our amps our made and audition them with the selection of speakers and components we have on hand.


Related FAQs

Will the ZOTL40 Reference amplifier pair well with my speakers?

The ZOTL40 Reference amplifier outputs 46 watts per channel into 8 ohms, and 51 watts per channel into 4 ohms.

To help guide you in speaker / amp selection, we have developed speaker recommendations for each of our amps. It is important to note that LTA amplifier owners have found great enjoyment using their amps with a variety of speakers outside of the below ranges. The below are guidelines, not rules.

  • Critical listening environments: 85db sensitivity and above

  • Smaller rooms / lower volume levels / non-critical listening: 80db sensitivity and above

If you have questions about your specific speakers, chances are someone we know has tried them. Don’t hesitate to reach out with questions about your specific setup.

Some of the wide variety of speakers that have been heard to work well with ZOTL amplification: Quad 57s, Maggie Minis, Tekton Design, Fern & Roby, Voxativ, Janszen, Decware, Klipsch, Silverline, Spatial, DeVore, Daedalus, Zu, Ryan, Living Voice, Omega, and many others.

Also, don’t forget we have a 14-day no-questions-asked return policy.

Need more power? The ZOTL40 Reference amplifier can be used as a monoblocked pair configuration to double the power output of each amp. This is easily done at the flip of a switch on the back of the amp.


Related Products

ZOTL40 Reference Amplifier

The latest iteration of LTA's EL34-based amplifier, the ZOTL40 Reference amplifier is an end-game component for guaranteed excellence in any environment.


Related FAQs

Will the ZOTL Ultralinear amplifier pair well with my speakers?

The ZOTL Ultralinear amplifier outputs 20 watts per channel into 8 ohms, 22 watts per channel into 4 ohms.

To help guide you in speaker / amp selection, we have developed speaker recommendations for each of our amps. It is important to note that LTA amplifier owners have found great enjoyment using their amps with a variety of speakers outside of the below ranges. The below are guidelines, not rules.

  • Critical listening environments: 88db sensitivity and above

  • Smaller rooms / lower volume levels / non-critical listening: 85db sensitivity and above

If you have questions about your specific speakers, chances are someone we know has tried them. Don’t hesitate to reach out with questions about your specific setup.

Some of the wide variety of speakers that have been heard to work well with ZOTL amplification: Quad 57s, Maggie Minis, Tekton Design, Fern & Roby, Voxativ, Janszen, Decware, Klipsch, Silverline, Spatial, DeVore, Daedalus, Zu, Ryan, Living Voice, Omega, and many others.

Also, don’t forget we have a 14-day no-questions-asked return policy.

Need more power? The ZOTL Ultralinear amplifier can be used as a monoblocked pair configuration to double the power output of each amp to 40+ watts. This is easily done at the flip of a switch on the back of the amp.

Note for high-sensitivity speaker owners:

You may have heard that the ZOTL Ultralinear was designed specifically for highly sensitive speakers. This doesn’t mean it won’t work with low sensitivity speakers, just that the unique benefits of the ultralinear topology - namely the high levels of detail and slightly more refined, less forward presentation - will be more noticeable in high sensitivity speakers.


Related Products

ZOTL Ultralinear Amplifier

The ZOTL Ultralinear is the latest amplifier design by David Berning: the first ultralinear amplifier not limited by traditional output transformers.

Can I upgrade my ZOTL40 / ZOTL40 MkII to a ZOTL40 Reference amplifier?

Yes.

We value the loyalty of our customers, and in order to protect their investment, we take care to offer upgrade paths for our products.

The ZOTL40 Reference Upgrade Program is designed to offer existing ZOTL40 / ZOTL40 Mk II amplifier customers all the benefits of the new ZOTL40 Reference amplifier at a fraction of the price.

If you are an existing ZOTL40 amplifier owner, we invite you to take advantage of the ZOTL40 Reference Upgrade Program.


Related Products

ZOTL40 Reference Amplifier

The latest iteration of LTA's EL34-based amplifier, the ZOTL40 Reference amplifier is an end-game component for guaranteed excellence in any environment.

ZOTL40 Reference Upgrade Program

As a ZOTL40 owner, we want you to have the best possible sound in your system, so we are pleased to offer an upgrade program for you to get all the benefits of the new ZOTL40 Reference at a fraction of the price.


Related FAQs