Coffman Labs H1-A: Full Review

  1. sheldonkreger

    Overall Impression
    The first time I tried the Coffman Labs H1-A was at the Portland Oregon user meetup at Echo Audio. I tried a lot of great equipment that day, but the H1-A was the piece of gear that really caught my attention. Not only is it eye catching, it had a remarkable affect when I listened to some of my favorite recordings. I gave the engineer, Damon Coffman, a bit of feedback about my perception of the way it affected a few different headphones that day, and a few weeks later, he contacted me to review the first production unit, coming right from the Coffman Labs shop in Hillsboro, Oregon.
    Coming to pick it up at the store, we warmed it up and I listened closely through a Senneheiser HD-600. By luck, they had Dave Grusin's “Early AM Attitude” playing through the CD player. Now, “Early AM Attitude” is one of those songs where I can name the musicians, the year it was produced, the label, etc. all off the top of my head. I was completely blown away, overwhelmed by the level of detail. I immediately burst into a fit of laughter and had to set down the headphones, take a few deep breaths, and try to maintain an adult-like composure in the audio store. It was pretty overwhelming to hear my favorite musicians from a fresh perspective, and I decided it was probably best if I turned the unit off and waited until I got home to explore further. 
    As a drummer, I pay very close attention to the sound of drums. Different styles of music require different techniques and instruments in order to be played convincingly. Over time, I have realized that what distinguishes my favorite drummers isn't just their ability to play, but their dedication to using the best combination of cymbals, drums, and other equipment for a particular performance. They also have the ability to respond to the coordinative and technical demands each drum set requires. Knowing which instruments to use for a given musical situation – and how to adapt their playing to utilize those instruments – is what distinguishes the best drummers today.
    Once I had everything set up at home, I started experimenting. It was a lot of fun, and I learned a lot along the way.
    Using the H1-A paired with appropriate headphones taught me that a dedicated listener can connect with the musicians they listen to on a deeper level. I have realized that the listener faces a similar set of challenges when recreating the sounds they are listening to. Although I don't have enough experience to say that the H1-A is “the best” at delivering the intended sound that my favorite musicians have in mind, I can say that using the H1-A has made me aware that the listener has a responsibility if this goal is to be achieved. 
    If music is to be played, recorded, and heard at a later time, the instruments that the end listener chooses play a very important role in that process. Using the H1-A opened my mind to the challenge of recreating musical performances effectively, simply because it does it so well.
    Lessons I Learned

    (My desk at OpenSourcery - Don't bring your toys to work!)
    Everything is Important
    There are many pieces of the puzzle in the journey of recreating sound. An effective recreation of living music is a unification of factors including the quality of the instruments recorded, the way they were played, the microphones used in the session, the mastering, the format of the sound files, the EQ, the headphones, and so on. The headphone amplifier is one piece in that chain.
    Several Improvements to Small Details Add Up to a Big Jump in Quality of Sound
    Putting all of these pieces together is complex, and there are many different factors which contribute to the end listening experience. Refining the quality of the sound means honing in on not one, but many small details. Damon Coffman, who engineered the H1-A, is aware of this and places great value on each small modification he made to the amplifier.
    High End Gear Exaggerates Both Positive and Negative Qualities – And That's Good
    I did some experimenting with low quality headphones, poor recordings, strange EQ, and so on while using the Coffman Labs H1-A. Strangely, it was actually very fun and enlightening to hear the negative qualities of sound be amplified so clearly. Hearing what is bad, better, made me more aware of those problems, and how to listen for them. This was an unexpected learning experience I had while reviewing the Coffman Labs H1-A. As a listener and aspiring sound engineer, I realized that I need to be aware not just of what sounds good, but also of what causes music to sound bad.
    Different Tools for Different Jobs
    A headphone amplifier isn't going to magically make all of your music sound amazing. Music must be paired correctly with headphones and EQ to really shine. Although the Coffman Labs H1-A didn't magically make any of my headphones match any different music than before, it dramatically improved the quality of the sound when a match between the headphones, EQ, and music was present.
    Active VS Passive Listening
    Most people listen to music while driving, working, studying, or doing something else. This is passive listening and high end audio gear isn't going to provide much value to those situations. However, people like myself actually make time to sit and listen intently on music. My time is valuable enough that if I'm going to spend time listening to music, I want to have the highest quality experience possible. I'm the kind of person who really pushes to be the best at everything I do, and using the H1-A helped me realize that listening is also a skill which requires time and equipment to master.
    Your Instruments Should be Better than You
    I was recently watching a video of Russ Miller explaining a few components of his drum set, and he made the point that as a professional studio musician, it's important to not only have instruments that do the job, but that they are inspiring and supportive to your playing. When musical equipment responds the way you expect – and only brings you pleasant surprises – your playing feels natural and is elevated to another level. Using the Coffman Labs H1-A showed me that the same is true for listening equipment. When everything in the chain is lined up – the music, headphones, amplifier, EQ, etc – something special happens that can't really be achieved if you are making compromises.
    The Hardware
    - The H1-A is completely analog, with the exception of the LED on/off switch on the back.
    - The knobs are military grade, heavy duty. I can't imagine these things ever breaking, but they are completely beautiful.
    - There are both quarter and eighth outputs on front, which is very convenient.
    - The back has two eighth inputs, a stereo input, and a stereo output on the back.
    - Ground lift switch on the back.
    - Power switch on the back.
    - Source selection, volume, impedance selector. The source selection allows you to plug in multiple units and switch between them freely. The impedance selector has three settings - high, medium, and low. All of the knobs feel very solid and operate smoothly. There is no noise when the knobs are turned while playing music.
    - Tubes - two 6C4 and four 50L6.


    The Sound
    Overall Changes
    I tried the Coffman Labs H1-A with several different headphones, and compared the sound of each with just running them directly from my sound source. Consistently, using the H1-A made the sound more immediate and clear, but less shrilly and less separated. That's not to say that separation between instruments was poor – in fact, the separation between instruments improves with the H1-A – but rather it is the separation between tonal ranges which seems to diminish. Rather than hearing highs, lows, and mids with individual qualities, the H1-A blends all of the music into a unified performance unlike anything I've heard before. The natural blending of sound is probably a reflection of Damon Coffman's goal of recreating the live performance with the H1-A.
    The second major difference I notice while using the H1-A is its impact on soundstage. No matter what I plug into it, the soundstage opens up vastly, and the music seems to have room to breath, expand, and fade away. Again, this contributes to the feeling of sitting in a concert hall watching a live performance.
    Effect of Impedance
    Changing impedance is easy and fun to experiment with on the H1-A. There are three settings (High, Medium, Low) which allow you to get a good match with whatever headphones you are using. In some cases, I used different levels for different kinds of music and mixes, even with the same headphones. There aren't any 'general rules' that apply, it's just a matter of finding the right match with the music and the rest of the equipment.
    Paired with AKG K702
    The K702 is a reference headphone meant for mixing and mastering situations. They provide a very high quality, detailed, analytical, and neutral sound. It might not be the most “pleasant” sound, but I really enjoy listening to music this way, because it gives me an accurate representation of what the sound engineer intended to deliver.
    It is also worth mentioning that the K702 is notoriously difficult to power, but that the H1-A had no problem delivering the juice.
    The headphones are very sensitive to EQ and perform well with certain kinds of music – jazz, acoustic, classical. Really, any recording of a real musician playing an acoustic instrument sounds great. Acoustic guitars, banjos, pianos, etc. sound extremely accurate and detailed. 
    I really enjoyed listening to some of my favorite acoustic bass solos through this setup. Many sound engineers complain that the double bass is notoriously difficult to record. As a conscious listener, I know that the of the bass sound is overshadowed very easily by other musicians. However, this setup effectively blends all of the sounds coming from the band into a unified presentation, without pushing out the acoustic bass. Even when nobody else is playing, it is almost impossible to recreate the most important details of a bass solo. In fact, I was unaware that it was even possible to hear this level of clarity and definition on a recording. During a live performance, you don't just hear notes. Instead, you hear the way the musician moves their fingers up and down the fretboard, the way the fingers pull the strings, and the slapping and buzzing of the strings on the instrument. You also hear the dynamic relationship between different strings when they are played simultaneously. All of these things are typically removed from the end listening experience – and I thought that was a result of the recording process. This setup taught me that it's possible to recreate many of the most important qualities of a live acoustic performance when the listener is dedicated to using the correct combination of listening tools.
    Everything I outlined about listening to acoustic bass on this setup applies equally for all other stringed instruments, including violin, cello, guitar, banjo, mandolin, etc. My favorite blues album, “Blues Dream” by Bill Frisell features many stringed instruments layered together. Listening through this setup allowed me to hear the sounds from each and every string in the orchestration in a detailed and dynamic manner. I didn't realize how much I was overlooking the role of sustained notes played harmoniously on various stringed instruments until I experienced this combination of instruments.
    Of all the combinations of music and equipment I've ever tried, the K702, H1-A, flat EQ, and modern acoustic jazz music is the most outstanding due to the impeccable recreation of the live performance it creates. I was completely unaware that music can be captured and played back in such a seamless manner.
    Paired with Sennheiser IE60
    I like to use the Sennheiser IE60 for listening to hip hop and other kinds of electronic music. They crank out the lows, which works really well for these styles. However, I often find that electronic music producers have a tendency to take lots of different, unassociated sounds and stack them on top of each other in a way that doesn't really come off as natural. This is a consequence of the huge libraries of sounds that they have access to and oftentimes their lack of experience with live musical instruments. I often feel like digital orchestrations are more like mish-mashes of random sounds broken into 16 bar chunks.
    However, when I do find electronic producers who really know what they're doing, it's a lot of fun to hear it. The Sennheiser IE60 works well in these cases.
    Pairing an in-ear system with this giant amplifier was somewhat comical, but the result was no laughing matter. Much like I've mentioned before, the H1-A has a way of pulling the highs, mids, and lows together into a unified presentation. This is true not only with acoustic music, but with digital music, as well.
    However, after a few minutes of listening, I realized that the H1-A compromises the important definition in the bottom of the lows that this style of music aims to highlight. This is yet another surprising lesson I learned from the H1-A: The electronic producers I like are creating a lot of sharp contrast between different sounds intentionally. And, when the H1-A imposes it's earthy, natural characteristics in this style, the end result was sort of like serving really good wine with really good pizza.
    There was an exception to this rule, which was listening to Burnt Friedman and Jaki Liebezeit. Although that music is largely digital and the drums are highly processed, for some reason, the way their albums are produced really worked well with the H1-A. This is probably because the producer is experienced with recording live instruments, and integrates digital sounds naturally into the music.
    I'm going to reiterate an important point that I made earlier, which is that there are different tools for different jobs. This is true in any kind of work or hobby, and headphones are no exception. As the listener demands higher levels of sound quality, the equipment becomes more specialized to meet increasingly specific demands. My experience is that the H1-A truly excels in recreating performances of acoustic instruments, because that was the goal of the engineer when it was designed. Trying to force it into a different role just isn't the right thing to do.
    I discussed this with Damon Coffman (the engineer), and he said, "My sense with electronica parallels yours and I decided not to make any changes that would compromise the acoustic music reproduction.  I think this was the right choice." I have to agree enthusiastically with Damon.
    By listening to the Coffman Labs H1-A, I realized that there are engineers who are truly dedicated to refining the listening experience to the highest level. The hours of work and dedication to sound from Coffman Labs are clear the moment you begin to listen. As a musician, it's inspiring to know that the music I produce can be recreated in such a convincing manner.
    In particular, the H1-A excelled with my favorite kind of music – contemporary jazz. This was also true for any other kind of organic, acoustic music I played through it, including classical, bop, blues, folk, bluegrass, and so on. That's not to say that it doesn't do well with other styles, but I am especially happy with its performance in these areas. When paired correctly with headphones, the H1-A creates impeccable balance between the different instruments in an orchestration. Every articulation is clear and never overshadowed by contrasting sounds coming from other instruments. 
    Hearing the H1-A makes it impossible to distinguish between harmonious blend and separation between instruments, due to its ability to create a unified performance. Its remarkable affect on soundstage also contributes to the feeling of sitting in a large concert hall. I honestly had no idea that it was possible to recreate a live listening experience so closely.
    Recommended Listening
    John Abercrombie - “The Third Quartet”
    Bill Frisell - “Ghost Town”
    Lee Ritenour - “Rhythm Sessions”
    Burnt Friedman and Jaki Liebezeit – Any album from the “Secret Rhythms” series
    Anything from the ECM record label
    Purchase Info and Social Media
    Find Coffman Labs on Facebook:
    Purchase the H1-A from Echo Audio:
    Feel free to contact Sheldon Kreger (myself) for reviews via
    Much thanks to Coffman Labs and Echo Audio for graciously lending me the H1-A to write this review.
    Thanks for the review on this esoteric piece of equipment. I really enjoyed reading it.  Can you compare the H1-A against any other tube amps you may have heard?  Also, what about heat?  With 6 tubes I'm wondering whether or not this amp would be uncomfortable in a smallish room.
  3. fabio-fi
    According to specs, this headphone amp is capable of delivering up to 1 Watt? im confused there. 
    some pics of the internals would be nice. 
  4. sheldonkreger
    I am pretty new to the high-end audio world, and I don't have much experience with different amps. Unfortunately, I can't draw any comparisons to similar equipment; I just don't have the experience (yet).
    Regarding heat, yes, the H-1A does create heat. I certainly don't think it's enough to discourage anybody from using it. Although I can't be precise, I can say that there is less heat than, say, a desktop computer. Because the goal of the H-1A is to provide the best possible reproduction of the live sound experience, I suspect details like this were much less important to the engineer.
    Let me know if you have any additional questions and I can forward them along to Damon Coffman, the engineer.
  5. CoffmanLabs
    Hi and thanks for the questions.
    The amount of heat generated is not very great--much less than an equivalent 4 tube 6V6 amplifier running in the 15W range.  I use it in my small office for the computer speakers.
    Regarding output--it will deliver between 1-2 watts to a speaker (4-12 ohms).  This is more than it seems due to the non-linearity of volume perception in the human ear.   Doubling the power only increases the perceptual volume by 3 dB, where 1 dB is defined as the smallest unit of change that the human ear can easily detect.  I use this amplifier in my 25' X 50' X 14' (high) workshop to drive 98dB sensitive speakers.  It is able to drive these speakers loud enough to drown out the machine shop next door.  My next amplifier jump (in my shop) is to 50 Solid State Watts, which is what is necessary to feel like there is a reasonable increase in power.  I could get about the same amount of perceptual power increase with a 7-10W Class A tube amplifier, however.
    Please note--we are still determining the best way to market this product.
    Damon Coffman
    Coffman Labs
    Hi Damon,
    Thanks for answering the question I asked about heat, and thanks Sheldon for an absolutely bang up job with the review.  Lots of information presented in an engaging style.  What I did miss though is how the H-1A compares to other headphone amplifiers.  At this stage I don't have a perspective on where to position the amp.  I'm also one of those pernickety folks who is located overseas so the opportunity to hear before making a purchasing is not an option.  There are a few key brands that are mentioned here on Head-Fi and even though I haven't heard them I can at least benchmark performance against cost by referencing reviewers whom I have come to trust.  For example, some of the respected tube amp manufacturers would be companies like Eddie Current (Balancing Act, Zana Deux, Super 7) Donald North Audio (Sonnet2 & Stratus), Decware (CSP2+ & Taboo MK III) and others like Woo Audio (WA2, WA22, WA5-LE), Cavalli Audio (Liquid Glass), etc.  It would be helpful to know how the Coffman H-1A performs in relation to these amps.  You mentioned about determining an effective marketing strategy.  I think one of the best methods is to attend some of the local, regional and national headphone meets and give enthusiasts the opportunity to talk about and listen to your products.  Another option that some vendors have done is to arrange a "loaner" unit to do the rounds amongst some of the more well known Head-Fiers with the proviso that they write a review.  I'm sure you have already thought of these options so please disregard my comments if they are a little naive.  
  7. CoffmanLabs
    No problems and thanks for the comments.  I am definitely planning to pass these among some of the members for a listen and write-up.  At this point, I'm just cleaning up a few final issues.  I realized that I needed to add an ultra-low output for the in-ear-headphones.  I've done that, but it means I need to paint and re-etch new front plates.  At the same time I also added an ultra-hi resistance output for the 600+ ohm headphones, since I was doing new plates anyway.
    I have had this out to a few audiophiles--and that is the reason I'm adding the two new output settings.  Soon as they are done and I have the new front plates I'll be looking to find some listeners on the forums.
  8. sheldonkreger
    I just wanted to follow up on this and share the new collaboration between Coffman Labs and Cypher Labs, the Prautes. It seems to me that this might be the highly improved model Damon was discussing last year. 
    I haven't heard it yet, but I am very excited to see the new improvements. Specifically, I'm excited to hear about the new outputs - XLR, SPK, 1/4, 1/8th. Also great to know the details about compatibility with speakers.

    I'm VERY excited about this!

Share This Page