Garage1217 Project Ember Hybrid Headphone Amplifier & Preamp

background -

my main amp has been an elekit 8200 that i built in 2018, it uses 2 power tubes and 2 preamp tubes. i got it primarily for speakers. it was my first tube amp and ive never looked back (at solid state) since. over the years, i've rolled a lot of tubes with-it and am pretty sure of the sound i like (warm, 3d/holographic with bass).

earlier this year, i realized when listening to headphones i could use a smaller amp. the main reason is the elekit is like a small space heater and makes my room hot especially in the summer. plus i realized i could trim the tube collection- i had enough tubes to last several lifetimes (this is only half of what i have!). and of course, since i had a bit of cash from the tubes i sold, i wanted to try something new.



i found the ember via a comment on reddit when looking specifically for amps that use a 12au7 or 6sn7gt tube (since i already had them for my other amps). since the ember can roll those plus so many more, it was a no brainer buy. i knew long term it would save money (single tube required)


sound
with the tubes i've tried, in general i'd say the sound is smooth, detailed and refined just like you'd expect from a tube amp with beautiful harmonic distortions and easy relaxed listening. of course some of the characteristics change depending on the tube used but since i have mostly the tubes i already know i like (12au7s and 6sn7gt), it wasnt much of a surprise hearing them on the ember instead of the elekit.

after listening for a few weeks, heres what i tried and took notes on-

1. Tung sol 6sn7gtb is probably one of the clearer more balanced ones i've listened to so far.
2. RCA (red label) 6sn7gtb one of my favorite 6sn7GT tubes, warm lush and wide sound stage
3. GE JG 5814As are one of my favorites, with one of the tubeyest and balanced sound ive heard yet. they're my favorite on the elekit and also on the ember.
4. Amperex 12au7 bugle boys- holographic and well rounded like theyre known for
5. RCA 12au7 clear top- clear airy and transparent with a nice sparkle in the treble
6. Tung sol 12AV7 - excellent bass and midrange with a very smooth, liquidy sound and pleasant vocals. very forward treble and soundstage (higher gain than 12au7)
7. Dumont 12BH7 - a little light on the bass with vocals a little more recessed than others but overall good for some classical (or non bassy music)
8. RCA 6GU7 - thought this tube had a very neutral to average sound, but good soundstage and resolution

the amp sounded great with all of the music i listen to (mostly rock, blues, electronic, classical and jazz), but i think tube sounds mostly do best when real instruments or vocals are present and especially so with live (concert) recordings. with electronic, the tube sound is not always as obvious to me at least.

power
i only have a couple of pairs of regular headphones that i tried it with- ath r70x (470ohms) and avantone planars (32ohms) and with both it has plenty of power and was dead quiet with nothing playing. most of the time i had the volume around 10-11am with the athr70s and the impendence jumper on high. you can switch it to medium or low which will make the volume even louder at the given setting.




conclusion
the ember holds its own against my elekit. it gives me exactly what i wanted as far as the tube sound goes with plenty of options to try different tubes and experience the same music in different ways. in fact, if it had a speaker output, i might even consider selling the elekit.

if youre curious or looking for a headphone tube amp, not sure theres a better option out there with the support, warranty and freedom to try all the tubes the ember supports (and also self biases so you dont have to) and plus you can use it as a buffer or preamp if you want to connect it to your solid state speakers to get a little tube sound there.

for the forseeable future i dont think i'll be changing much if any of my audio equipment. very happy with the elekit, the ember, and of course my more recent foray into stax.

I picked this up recently and drove a TON of different headphones with it. I thoroughly enjoyed getting to know this amp. It has a lot of strengths. The amplifier in it has arguably fallen behind more recent competition, but the preamp performance is still excellent. It's a tinkerer's dream: support for a almost every 9-pin 6V and 12V tube type out there; jumpers to toggle 3 output impedance settings (for adjustable damping factor); jumpers to bypass input capacitor or input resistor or both; 2 gain settings. It can be bought as a kit if you're looking for a fun project or can come pre-assembled for about $100 more. More complete thoughts in the video:

So up for review/comparison is a Modded APPJ pa1502a an stock G1217 Project Ember II and a stock Schiit Valhalla 2

My Ember II has a CNC Chassis 1940 Vintage Sylvania 6sn7 JAN CHS VT231 Bottom Getter Flash Clear Top - $455 as tested if bought New

• Ember II Assembled - $390
• 6sn7 Adapter - $26
• 1940 Vintage Sylvania 6sn7 JAN CHS VT231 Bottom Getter Flash Clear Top - $39

[Though it's the longest established and can be gotten second hand for closer to $350 often with upgraded Tubes or you can opt to assemble it your self and save a little there too]

My Modded Set has a set of Russian 6n6c Power Tubes with a 1940s Sylvania 12SN7GT Driver - Cost as tested is $394

• Appj pa1502a Base Unit - $199
• Pair of 6n6c Power Tubes - $20
• Pangea AC 14 Power $30
• 1940 Vintage Sylvania 12sn7GT JAN CHS VT289 Bottom Getter Flash Clear Top - $10
• Audio Note Kasai + Auricap XO Re-cap an installation - $125

The Valhalla 2 is 100% Stock! - $350

As some one whose spent a lot of time tube rolling and modding/tinkering I was really curious to see how a stock amp like the Valhalla 2 compared to my rolled in wonders.



Overall I felt my Modded APPJ pa1502a was the most resolving, audibly it had the highest degree of fidelity or exactness in reproducing sound when specifically paired with dynamic headphones. The mods we did were;

• Replaced existing Output Caps with AuriCap XOs & Audio Note Kaisei's
• Introduced bypass caps into the Circuit Path

All in all it's the result of about 7 months of research and I'm very impressed with the results! At the end of it all I feel if your able to DIY your likely going to get the highest degree of fidelity for your system with the least monetary cost. But there's extensive knowledge and experience required as any mistakes invoke additional cost. I also had to do some digging to figure out who to have install the mods, as I'm not cleanest solderer. So again time and money can quickly add up when putting together a custom piece. I suppose I lucked out!

But in a sense I feel it's a bit unfair to compare an amp Modded specifically for my exact system, still I wanted to include it to get some perspective on how a more DIY Focused option compares to available retail products. An I'm happy to say there was in fact a retail amp that followed closely behind my own Modded SET! So much so I kinda wish I'd purchased said amp before venturing into my own little experiment.



I did my listening with a ZMF Auteur in Cocobolo with their Silver Michanikos cable as well as with my HD 800 using a Audio Envy Tone Kraft Copper.

Each of these I felt was a headphone that had a more natural mid range presentation with even bass response, the HD 800 is brighter up top and very technical with strong staging and the Auteur was a bit more intimate with a more correct timbre and more even tonal response.

An I personally enjoy each with a drier sounding tube amp, so the three amps featured all share that slightly drier presentation in comparison to something like a Schiit Vali 1 or a Cavili Liquid Glass with a thicker sounding Tube.

An again overall I felt my Modded APPJ pa1502a had the most resolve and audible fidelity how ever on high gain an at over 80% rotation I also noticed it was nosier than the other two amps. Thankfully only about 10% of my music requires me to push the amp to this upper limit, and even then I've got around 3-4 dBs of headroom.

But I'll go over 4 aspects of sound quality in comparing the remaining two units;

• Detail
• Dynamics
• Staging
• Tonality/Timbre/Envelope

An as you guys know each of these aspects are often linked together, as tonal imbalances can often lead to perceived changes or in-inaccuracies in regard to staging as well as mask over some detail.
Overall I felt these aspects of the Valhalla 2's presentation were better than that of the Ember II;

• Black background
  • With less audible noise, hum or hiss present during silent or quite passages
• Clear Micro and Macro Dynamics
  • Gradual changes of individual instruments and musicians were easily identified
  • As were more sudden and intense changes to the intensity of the composition as a whole
• Vivid Presentation of Transients
• Tauter Bass
  • With a cleaner more balanced envelope - so no emphasis on attack, decay sustain nor release

Overall I felt the Ember II presentation was stronger in these aspects;

• Staging
  • More precise location of movement of sounds within the audible space
• Resolved more of the "sound of the room"
  • Such as ambient noise like wall reflections, echo's and things like foot steps
• More Even Tonal presentation
  • Overall neither forward nor withdrawn throughout the frequency response

In comparison I felt the Valhalla 2 did the following different from the Ember II

• Slightly Forward Mid-Range
  • While tonally not as balanced I did feel the Timbre was more natural
    • With a more even presentation of each part of the envelope
  • Slight forwardness helps define space for more intimate headphones but ultimately skews precision in staging for more open or spacious sounding headphones

In comparison I felt the Ember II differed from the Valhalla 2 in these aspects;

• Some What Polarizing Presentation
  • Slight emphasis on attack and decay over sustain and release on in the mid range an upward
  • With contrasting emphasis in the lows
  • In a sense this some what polarizing presentation is more "tonally" correct but...
• Slight emphasis on Ambient Noise
  • Part of why I feel it's staging is slightly more accurate

An finally I felt the Ember II did noticeably worse in these aspects in comparison;

• Noisier
  • More audible hum and hiss during quite passages
• Looser low end presentation
• Some what skewed timbre
  • Again odd presentation creates a nice tonal balance but skews the overall balance in how the envelope is presented which makes the timbre kinda off

An lastly I felt the Valhalla 2 had this single fault;

• Slight Glare or Hardness
  • A rougher top end texture alongside an unpleasant upper mid glare

So it was quite fatiguing with really bright or energetic cans like those from Audio Technica or even the Filter-less Campfire Audio Cascade.



An yes I also felt the Valhalla 2 did give my little Modded Amp a real run for it's money!!! Thankfully, I have purchased an upgrade to my system so my experiment isn't holding me back at this time, though I wonder how much sooner I might have gotten said upgrade if I'd just gotten the Valhalla 2 in the first place...

An I again choose to limit this review to just dynamics as I felt the Hybrid Ember II had a clear advantage driving my Hifiman HE 560 and PreFazor LCD 2. An I've found that typically at this price points Hybrid Units seem to do better with harder to drive Planar Magnetics. Though exceptions may exist and I may explore them in the future.

Though with that Said the Ember II biggest strength is it's versatility.

As a single tube swap can make small changes to;

• Audible Noise/Gain
• Tonal Balance
  • Timbre or presentation of the envelope

You can also change how the circuit operates and these changes bring a slight adjustment to;

• Audible Noise/ Gain
• Timbre

It's also far more powerful then either amp so it's got much more headroom on tap.


To this day I still feel the Ember II is an excellent choice for very power hungry Legacy Planars like the two I own, and I feel the circuit mods help to balance out the sound of these as well. Helping each to be a little more natural, while still be exceptionally "fast" sounding overall. In fact many of the weakness of the Ember II with my dynamics are in fact strengths with my planars as they have a some what contrasted presentation over my HD 800.

So for those of you that own large collections of headphones that have very differing sound presentations and amping requirements the Ember II will likely remain an excellent choice given how easily you can adjust it's operation to compliment a variety of gear and sound signatures.