Over the past 20+ years I’ve had at least one tube amplifier in my life in one form or another. Most tube amplifiers I’ve had were power my 2.0 speaker setup. Then about 12 years ago I became a father for the first time and I quickly realized that my speaker listening would be severely limited; thus my foray into headphones began. So being a long-time tube fan, I searched for a well-priced and strong performing headphone tube amplifier. I settled on the venerable Mapletree Super Ear+ HD by Mapletree Audio. Dr. Lloyd Peppard, (Ph.D.) is a retired Electrical Engineering professor and has used this extensive background and designed some really impressive products through the years. Well, the relatively newer SugarMaple brand has been released within the MapleTree Audio banner. These amplifiers are designed by Dr. Al Freundorfer (also an electrical engineering professor, Queen’s University in Kingston, Ontario).
When given the opportunity to review the new all-octal tube amplifier, I jumped! The design motif is very similar to the rest of the Mapletree lineup. They offer a much more antique look when compared to the tube amplifiers by Woo Audio. I’m a big fan of the throw-back design character when paired with vacuum tubes and the SugarMaple OD300 does not let down. A strong point in my opinion is you won’t have to break the bank in buying vacuum tubes to run this amplifier; all you’ll need is a single 6080 power tube (a 6AS7G equivalent) and a single 6SL7GT triode drive stage tube. I’ve had some amplifiers where I’ve invested almost $1000 in vacuum tubes alone and thankfully the OD300 (OD stands for the Octal Duo design used in this amplifier) avoids this and while you can still readily tube-roll to your heart’s content to find your sweet spot, you won’t have to spend a small fortune to get you there.
The specifications for the SugarMaple OD300 headphone amplifier are:
|Power Out into 32 Ohms; HiZ output||700 mW|
|Power Out into 16 Ohms; HiZ output||1400 mW|
|Frequency Response||10 Hz–40 kHz, -1 dB|
|Gain (1 kHz; HiZ output) gain is approximately 3 dB lower at LoZ output||9 dB|
|Tubes supplied||1×6080 (NOS) 1x6SL7GT (new)|
|Input impedance||50k Ohms|
|Output impedance (LoZ output) output impedance is approximately double for HiZ output||1.1 Ohms|
|Recommended headphone impedance (Any headphone impedance can be connected to either HiZ or LoZ outputs with a 3 dB reduction in output level for LoZ at same volume setting.)||16–600 Ohms|
|Power consumption (120 VAC or 240 VAC, 50-60 Hz)||90 W|
|Footprint||two chassis 6″ x 10″|
|Options||• 6AS7G output tube|
|Appearance||black chassis with oak corner posts|
With the very low output impedance (only 1.1 ohms) and power available (up to 1.4W into 16 ohms), I found the SugarMaple could literally handle all the headphones I threw at it with great ease and the sound quality was outstanding! Also available are two output headphone jacks; one for low impedance headphones like my 32 ohm PS1000e Grado flagship headphones and a high output impedance jack for higher impedance headphones like the 300 ohm Sennheiser HD800S and 600 ohm Beyerdynamics T1 (Generation 2) headphones. With this amplifier, you can have your cake and eat it too. The black metal chassis and oak corner posts offer a seductive antique design that come to life when the tubes fully illuminate. The dual chassis design does indeed help push the noise floor down to almost that what I expect from a solid-state amplifier. Some tube amps that I’ve owned through the years did suffer from a low level hum (especially with very sensitive and low impedance headphones), but the OD300 could be easily used with even in-ear monitors; to say the least, I was very impressed with this feature.
The measured performance suggests a very natural sound and based on my first hand experience definitely matches up quite nicely with what I hear when using this great amplifier:
The bass is nice and emphatic without a hint of a roll off and the treble is nicely extended without any glare or stridency. So with that, on to the sonic characteristics of this amplifier…
Having previous experience with the venerable Mapletree Ear+HD and Grado headphones, I first selected my limited edition Grado GH-1s. Being in a somewhat sentimental mood, I decided to listen to The Tragically Hip’s: “Fully Completely”. With their recently last concert ever due to Gord Downie’s diagnosis of terminal brain cancer, I have really gone back to this old favourite band of mine and rediscovered so many of their great hits. “At the Hundredth Meridian” and “Fifty Mission Cap” were rocked! And like the Ear+HD, the SugarMaple OD300 was just as nimble and euphonic with Grado headphones. Simply put, this combination really sounded great! I put the same album through its paces again, but this time with the Grado flagship PS1000e headphones and like with the GH-1s, there was a certain magic with the OD300 that I’ve only found with a select group of headphone amplifiers. The sound signature was certainly tube-like and offered a wonderfully rich and vibrant experience. The euphonic nature however seemed neither slow, nor overly warm in any way. As well, I found the amplifier; while slightly tilted to the warm side of things, a very natural sounding unit that wasn’t overly “tubey”. This is a very good thing as with previous tube amplifiers that I’ve owned through the years, the excessively tubey ones can really impart too much of their own specific sound into a recording. The OD300 seemed to balance this line perfectly with solid state tactility and a tube amplifier’s naturalness.
I particularly found the Sugar Maple OD300 a wonderful match for my Sennheiser HD800S flagship headphones. These headphones are notoriously difficult to drive “properly” and can come off as a bit dry or clinical when the amplifier isn’t really up to par. This was certainly not the case with this wonderful tube-amplifier, instead the HD800S headphones were wonderfully quick and full presentation. Pink Floyd’s “The Wall” really came alive when using this combination. The heartbeat at the very beginning of “Speak to Me” was gloriously detailed and the ability of this pairing to dig deep into the recording and pull out the smallest nuances of the reverberations and setup an almost speaker-like presentation really knocked me off my seat. I ended up listening to this three of four times in a row to fully grasp just how impressive this sounded. The clanging cash registers in “Money” seemed to whirl around my head and filled the sound scape with a truly three dimensional presentation. However, with some amplifiers that I’ve tested, these cash registers could come off as a bit too bright and strident. Thankfully that was not the case with the OD300 amplifier. Instead all the brilliance, detail and quickness of that section were all there, but without the etched upper registers. I quickly realized that with the SugarMaple OD300, you can indeed have your cake and eat it too!
Simply put, this amplifier impressed me! Not only do you not have to break your bank in tube-rolling this amplifier (like say with a 300b tube based setup), you get a wonderfully natural sounding tube-based player that doesn’t hold back the smallest details in a recording or the quickness of your particular pair of headphones. Throw in the attractive retro-styling of this amplifier and you have a real winner. If you’re in the market for a higher end tube amp, I strongly suggest you consider the SugarMaple OD300.
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