Thursday, July 12, 2012
Review: Eico HF-60 tube monoblocks
EICO, unlike McIntosh, Marantz, or Fisher, isn't quite spoken with the reverent tones with discussing the best of the vintage amplifiers, but to do so would be a mistake. From their budget units, up to the the flagship model, the HF-60, they represented a serious competitor to Heath and Dynaco, offering good value for the hobbyists of yore. When I had the rare and unexpected chance to buy a pair, I went for it, knowing I would be hearing with one of the best EL34s amplifiers around.
So what is an EICO HF-60? It's a monoblock amplifier - requiring two for stereo - featuring 5AR4 tube rectification, the classic Mullard 5-20 circuit with an EF86 and 6SN7 driving EL34 output tubes in Ultralinear, fixed bias, and the legendary Acrosound TO-330 output transformer. There's nothing tricky going on here circuit-wise: current sinks, current sources, regulators, dc filaments, etc are non-existent, but component quality is still quite high with wirewound resistors, good tube sockets, and a really nice hunk of iron. Biasing is through two pots: one to balance between output tubes while the other is raw bias. These came as very basic kits with no circuit boards: the end-user was expected to be experienced enough to do point-to-point wiring.
Another thing to note is the high plate voltage and bias, making the HF-60 run steep Class A. 500VDC on the plates with 65mA means the EL34 output tubes are running 32.5Ws (plate + screen) of dissipation, right on the bleeding edge of their maximum rating. If the lights are off, a faint red glow can be seen on the plates(!) which, according to the manual, is considered normal operation! Back in the day, this was no big deal since you could pop down to the local store to pick up your new set of Mullard EL34s, but now with the high price of quality old-stock tubes, a user of this amplifier may want to dial back a few milliamps.
Not Quite Stock
Before I go and describe the sound of these amplifiers, I would like to mention that mine aren't exactly stock. Of course these days it's hard to find a vintage tube amplifier that sports its original power supply capacitors, but my set of EICO HF-60s came with some additional modifications that will effect the sound. First off was the addition of a small choke in the power supply. The original just used 40uF of electrolytic to clean up the voltage. Instead, I have a 25uF electrolytic bucket, followed by a 1.5H choke, and then a large 40uF Suzuki polypropolene capacitor. This change gives a clean and fast power supply. The second modification is to the EF86 input tube which now uses a battery to supply the bias. This was done by the local "tube guru" and is purported to clean up the treble and whatnot. Original coupling caps have also been replaced with MIT RTXs and some Jantzen Z-Superiors.
Tubes used for this review: Genalex CV4085, GE 6SN7GTBs, Mullard XF2 EL34s, and Hitachi 5AR4s.
Expectations were high when I dropped the needle on Side 2 of Supertramp's Crime of the Century. I've often been disappointed by audio purchases since the hype doesn't often live up to the reality. In this case I had nothing to fear - within seconds I recognized that the EICO HF-60s are something special. They really gripped the UREI 813A speakers hard, delivering power in an effortless way, all while casting a big, deep and detailed soundstage. It thoroughly demolished the budget wunderkind Yaqin MC-10T, and my memories of other tube amplifiers - the Dynaco 70, Dynaco Mark IV, Dynaco Mark III, Harman Kardon Citation V, Heath UA-1, various Scott, Heath, and EICO integrateds, and anything else that I missed over the years of this crazy hobby. The EICO also beat out my now departed Threshold S/500 or any other solid-state amplifier I've owned (which hasn't been many).
Okay, enough gushing already, eh? In order to give some further insight into these amplifiers, I invited a fellow longtime audiophile friend over to listen, hoping a second set of ears would keep my effusive praise somewhat in check. After spending a chunk of cash it's easy to get carried away with new gear, missing the warts and blemishes of music reproduction. We listened to a number of records and this is what we heard:
Steely Dan - Aja: Recorded by Roger Nichols, Aja's technical prowess - both musically and sonically - is laid out perfectly with the UREI speakers. The bouncy dynamics are engaging and fun, with plenty of little details to keep the brain locked into the music. At no time do the amplifiers run out of power - delivering the power effortlessly.
Grateful Dead - Terrapin Station: Side 2 of this album is a sorta short rock opera with bits of Renaissance-inspired flourishes and backup vocals. Yeah, it's a little cheesy at times, but still well-recorded with big dynamic shifts that sound diminished with lesser speakers and amplifiers. Needless to say, the EICOs passed with flying colors, keeping everything locked into place without ever sounding strained.
Faces - Long Player (German pressing): Not exactly an audiophile recording, the Faces good-time boozy musical party record sounds better than I ever heard it. Every instrument is audible, standing by itself in the soundstage without getting lost in the thick mix.
Supertramp - Crime of the Century (British pressing): before I got the UREI speakers, I always considered Supertramp to be lightweight rock 'n' roll music. But with the right system, the darkness of the music becomes more apparent. Once again the dynamics and bass impact was amazing, as was the midrange and treble detail. Soundstaging was deeeeeep, making my listening space sound like a larger than the confines of the walls.
Fleetwood Mac - s/t: Back when I was a kid, I pretty much loathed this 1975 album whenever my parents would play it. But changing tastes and Stevie Nick's wonderful voice on Rhiannon changed my mind. On this system, the high production values were evident, along with various multi-tracks used to create this sonic gem.
Bass: For the longest time, the king of bass reproduction was my Threshold amplifier. 250WPC with a huge amount of available current and the high damping factor helped to give some of the most fluid and detailed bass response I had ever heard. A known limiting factor of tube amplifiers has always been - at least in my experience - the slightly sloggy and underdamped bass. But somehow through the Acrosound TO-330 output transformer, those normal limitations are no more. Low frequencies are extremely accurate, controlled, and easily equal that of the massive solid-state Threshold. Amazing for a tube amplifier.
Midrange: They actually reminds me of an DIY amplifier I built a few years ago - a SE 300B design with a hefty SV83 pentode driver. The same kind of speed and snappiness, along with a natural reproduction of vocals, guitars, and everything else that dominates the most important part of the frequency range. No fine sand or loss of detail, but just a natural but uncolored presentation.
Treble: At my age, my hearing of highest frequencies isn't what is used to be, but still there was no sign of harshness or glassiness. I may niggle here and there and say that I've heard better - the above mentioned SE 300B design comes to mind or my SE EL156 amplifiers - but this is very fine hairsplitting indeed. Cymbals have a nice shimmer with natural decay while synthesizers snap and howl like the real thing.
Soundstaging: Deep, wide, and layered with everything sitting properly in it's place. At no point did the sound ever collapse or shorten like I've heard with several other amplifiers with undersized power supplies and output transformers.
Detail: I'm no hyper-detail freak, but the EICO HF-60s certainly didn't fog over the sound with a "tubey" mush or give fake information by cranking the upper-mids on up. Also different recordings sounded, well, different instead of congealing into the same tonality. I've heard plenty of tube amplifiers that suffer from "too much character", making every record sound as if it was recorded in the same studio.
I'll also note that I did some brief listening on the Magnepan 1.6/QR speakers and got great results, but the maximum volume was limited. Those speakers love to suck current and even 60Ws of tube power wasn't enough unless you enjoy baroque/folk/light rock music at moderate levels.
Okay, I hate to enthuse too much about just an amplifier since getting here has been a long journey. That's to say that an amplifier is only part of the chain of electronic reproduction. It took several other dead-ends and paths to finally come to this point. First of all, it helps to have a solid front end. Though not the best in the world, the VPI HW19 is still a solid performer, as is the Rega arm coupled to the Denon DL-103R and Cinemag transformers. The Quicksilver is really a nice bit of kit, and none of what I'm hearing would be possible without the amazing extension, speed, and explosive dynamics of the UREI 813A speaker. This same pair of monoblocks, especially stock, may not be quite so amazing with a lesser combination of gear. Back in the past, I used to be amp crazy, thinking "just the right amplifier" would catapult my system from mediocre to greatness. I've since learned that a solid front-end along with a good pair of speakers should be your first step before embarking on a path of expensive amplification upgrades.
Even though the EICO HF-60s are just a part of an overall, what I did hear from these amplifiers was a revelation. The most amazing part was the way they delivered power. I've owned some heavy-hitter gear in the past, but it's almost like the HF-60s "know" beforehand what wattage to deliver to the speakers. This sense of ease in reproduction just makes you forget about the amplifiers and instead just revel in the music experience. Yes, I've owned amplifiers that can deliver much more power, but they could never do with the finesse of this electronic antique. Much of this has to do with the Class A biasing, but also the Acrosound TO-330 output transformers. There is definitely something special about these hunks of iron. It's too bad that their design blueprint has been lost in the mists of time, though I'm sure some of the best offerings from Tamura, Magnequest, Tango, etc could match their performance.
It's been a long journey but I'm happy to say that I've finally found a pair of "keep for life" amplifiers. Until I hear something better at his price point - which may be possible - I will instead turn my attention to improving my turntable, stock up on my system's tube needs, and keep buying records.
VPI HW19 Mark III with SDS Power Supply
aluminum rebodied Denon DL-103R
Rega RB300 with Cardas wiring
Cinemag CMQEE-3440A in custom aluminum box
Cardas Cross 1M interconnects
Quicksilver preamplifier with Mullard short-plate12AX7s, RCA 12FQ7s, and a Raytheon black-plate 5814
Cardas Quadlink 5C 1M interconnects
EICO HF-60 monoblocks with Mullard XF2 EL34s, GE 6SN7GTBs, Genalex CV4085s
Cardas Hexlink 2M speaker cables
UREI 813A speakers
VTI BL503 equipment rack