How does or should a pair of HE833 sound? Well for most people, they would probably feel its top end is a bit too dark while the midrange is rich and warm, but somewhat mellow. To note, these are very muscular set of amps with high energy dispersion. However the bass lack of control has made it somehow slow, and yes, sluggish. It also sounds coarse during loud passages.
In my system however, they sound too seductive and compelling that keeps me away from another amp. It has a very transparent and detailed, crisp midrange with fast transient speed. Though the top end cannot match a good 300B type, it is still quite open, airy and never have the mellow feel. The mid bass is a bit fuller and dense. While overall the bottom end is fast, tight, dynamic and can rival a lot of solid state amps toe-to-toe. What I like most is the solidity, the HE833 makes all instruments sound alive, rock solid right in front of you where you can almost feel like touching them. But why some people have different opinions as mentioned above? Below is my root cause analysis:
1) Too sensitive to noise – any of ground, AC and vibration noise can downgrade its performance dramatically. Unlike other tube amps which turn these noises into something pleasant to ear, HE833 on the hand amplify them and therefore the top end will be darkened, midrange will sound coarse and bass will become muddy with no contour. Overall sound is blurred, noisy and forceful. Luckily, AE introduced several amazing products to tackle the noise problems. The Troy/Orion/Virginia team transformed HE833 into something beyond imagination. You can feel the background suddenly becoming extremely calm and everything is microscopic clear like someone replacing the soft lens with a high resolution one. Sound from each instrument presents with lots of tonal, textural and spatial information and the musical notes hang in the air with the right amount of harmonic decay.
2) Overflow of energy – indeed HE833 is a very powerful amp with high energy dispersion. If the listening area is not big enough to accommodate the sound, the reverbs will make everything noisy, intense and out of focus. Your eardrums will easily be fatigued after playing a big orchestral piece or a live rock concert. Like any other amp, room acoustics treatments and speaker location and proximity is very important for the optimum performance of this amp. You must painstakingly retune everything even when you change a PC or a pair of interconnect. I move my speaker by a quarter of centimeter incrementally whenever I change something in my system. That’s how tricky things get.
3) Mismatch of PC – well, FMR is a very good PC with respectable noise reduction; awesome speed and somewhat unlimited energy. Unfortunately it’s excess midrange and bass energy makes the HE833 sound intense and have the inflated problem. Pick a PC with very good extension to the top end, transparent midrange and light and tight bass. With the right PC, the midrange coming from your HE833 can be something you’ve never experienced before.
4) Mismatch of speakers – avoid using speakers that demands high damping factor amp. Mated with the wrong speaker, the bass performance can be catastrophic. Although my Affascinate is back loaded bass horn design, Ralph told me it can be driven by low damping factor amp. With precise speaker positioning especially the distance from the rear wall, it matches HE833 very well and thus delivering extremely fast and tight bass which can really move you especially when playing live rock music.
The technical measurements provided by Stereophile is not outright a guilty verdict but a good reference for system matching. Even if you have an amp with perfect linear specification, are you sure all other equipment and cables are linear as well? These are machines. Machines work its best in perfect matching systems. Besides, many amps with perfect technical measurements may sound terrible. I rather judge the performance by ears. If beauty is in the eyes of the beholder, then by same exact magnitude, it is in the ears of the listener.
As far as I can recall, when you used the HE833 to drive your Sunray, you were using FMR PC and didn’t have the full noise extinguisher team from AE. In addition to that, I strongly believe Sunray does demand a high damping factor amp to drive which explains well why all the problems you had encountered, is almost negligible or doesn’t even exist in my system.
From my past experience, power is never enough and even chamber music especially quartet and quintet demands a lot of power. But how many muscular amps out there can provide the same richness, transparency, delicacy and solidity to all live music. Tidal and Takumi are good however they over damped my Affascinate.
FYI, my recent references are mainly chamber music, soprano and live rock. I post this essay here is not to provoke any further controversial arguments, after two years of painstakingly battling with this big pair of monsters I would like to share my personal experiences with all other HE833 users. Of course if anybody wants to experience how these perform in my system, please feel free to drop me a visit. You are also welcome to bring along your amps for comparison. It will be interesting for sure.