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(left to right) Front view of Eddie Current HD25 (headphone cable is Zu Cable Mobius, interconnects are
CablePro Reverie v.2 and Cardas prototype); rear view of HD25 (interconnects are CablePro Reverie v.2).[/align]
PREFACE: The first headphone amp to really showed me what magic tubes can bring to headphone hi-fi was a pre-production version of the Antique Sound Lab Twin Head Mark II (it’s now available in a Mark III version). According to at least one person who’d heard both the pre-production unit I had and the final production version of the Mark II, they didn’t sound the same, the far better of the two being the pre-production version. I wasn’t allowed to purchase the pre-production version, and, given the alleged disparity between its performance and the production version's, I didn’t opt to buy a production unit. (NOTE: The distributor insisted that the pre-production unit and production units should have sounded the same.) That pre-production Twin Head Mark II, however, remains burned in my memory as a headphone amplifier in one of the three best headphone rigs I’ve ever heard (the other two involving the HeadRoom BlockHead and the Sennheiser Orpheus system).
After the departure of the pre-production Twin Head Mark II, I was tubeless (in terms of
headphone hi-fi anyway) for quite some time. However, with a HeadRoom Max, Meier Audio Corda PreHead (MkI) and Ray Samuels Audio HR-2 on hand, headphone listening bliss and bundles of musicality surrounded me, and the allure of tubed headphone amplification easily washed away. But, as it goes with Head-Fi’ing, the desire for something different can start with a mere tickle, before it eventually blossoms into full-blown desire. Just reading Head-Fi every day creates multiple tickles for just about anyone, including me. Someone posts about a MAD Ear tube headphone amp.
Tickle. Then I see mention of a Cary 300SEI.
Tickle, tickle. Then a recent visit to Ray Samuels Audio, which included listening to the upcoming Raptor and A10 (both are tube amps) in prototype forms --
whammo, full-blown desire found me. I found I again wanted -- no,
needed -- the option of having good tubed headphone audio at my disposal, to throw into my daily Head-Fi mix of top-class solid state power. With the sound of the little glass vials of vacuum beckoning, I soon had two tubes glowing ahead of my headphones in the form of an Eddie Current HD25.
First of all, I'm not the type to give much thought to how a piece of audio gear
looks, as is evidenced by the homemade, hand-cut vibration control pads under much of my gear, and my aesthetically plain-Jane (but
sonically reference-class) Cardas cabling. Nevertheless, if a component
sonically performs, and just happens to also
look the part, then you'll certainly get no complaints from me about the bonus. As you can see in the photo (which doesn't completely do the amp's appearance justice), the HD25 is a definite looker. Its chassis lines, old-fashioned knobs, and faceted power indicator light combine with the exposed tubes to present a decidedly retro appearance that has charmed everyone I've shown it to. If its external fit-and-finish is any indication, the HD25's build quality appears very good. (NOTE: Eddie Current’s Craig Uthus e-mailed me instructions on how to open up the HD25 for an internal peek, but I’ve so far refrained, due to an uncanny sense of timing on my part. You see, almost everything I open up -- electronics, watches, clocks, etc. --
coincidentally reaches the end of its service life at some point during my examination.)
The HD25 comes with an external power supply (that alone weighs more than most amps) in a matching metal chassis that contains the amp’s large power transformer. The power supply is permanently connected to the amplifier via a 3.5 foot umbilical cord, but its IEC inlet allows power cord swapping, for those so inclined.
Because it's transformer-coupled, the HD25 can drive just about any available headphone, from 20 ohms to 600+ ohms. I've tried it with lower impedance headphones by Grado, AKG and Sennheiser, and, though it sounds very good with those, it is no surprise to me (because it's a tube amp) that it plays particularly well when matched with the higher-impedance (300-ohm) Sennheiser HD600 and HD650 headphones, both of which seem to find love with good tube amps of all ilk. Don't get me wrong, though, if you have lower impedance headphones, and you're looking for something to show you what a good tube amp sounds like with them (and without breaking a sweat), the HD25 should be on your list of candidates.
The HD25 uses only two tubes, one 6AS7 (or 6080) and one 6SN7. The first 6AS7 that was shipped with it was a noisy Svetlana 6AS7 (a current-production tube), and it had the amp leaving me with some less-than-ideal first impressions. It
sizzle-hummed (best word combo I could come up with to describe it) very audibly in one channel, and it had me back on the solid state amps until I could figure it out. After discussing this with Craig, he decided to send a few more Svetlana 6AS7's and a few NOS (new old stock) 6080 tubes. Fortunately, ditching that first 6AS7 fixed things up
very nicely. First I tried one of the NOS 6080 tubes (RCA), and the amp ran with
no background noise whatsoever, and sounded awesome. Next I tried one of the other Svetlanas, and it was quiet, too, once again indicating that the first Svetlana 6AS7 was a lemon. After doing a little research on 6AS7s, I found that noise problems aren't altogether uncommon with current-production 6AS7's, with one amp manufacturer writing that he rejected one out of every four he tested. Get a good quiet one with good internal matching, however, and the current-production Svetlana 6AS7 can be a nice tube. However, since old 6080's tend to be quieter in general (and because they're easy and inexpensive to acquire
and sound good), I'd recommend that Eddie Current consider shipping the HD25 with a 6080 or old-production 6AS7 instead of the Svetlana 6AS7.
As for the 6SN7, I haven’t done much rolling of this tube yet, having only tried two kinds: first, a General Electric 6SN7GTB, and then an RCA 6SN7GTB. Understanding that these don’t represent the most heralded of the available 6SN7’s, the HD25 still sounds
wonderful with either of these tubes, with my preferences leaning toward the RCA, for rounding out the edges a bit, and sounding just a bit more lush and "tubey." I’m looking forward to trying some of the more respected 6SN7 types with the HD25 to see just how much more performance can be squeezed out of this amp. (If any of you 6SN7 experts have one you highly recommend that you’re willing to sell, please PM me.)
Before I go any further, I have to ask: Why on earth isn’t the Eddie Current HD25 one of the best-selling amplifiers in the Head-Fi community? First of all, it’s an extremely efficacious solution to tube-sound desire, serving up, in generous heaps, harmonic fullness, sensuous midrange bloom in just the right amount, and the richness of timbres that only good valve amplification (and exceptional solid state amplification) can convey -- and as a listener of mostly acoustic music, timbral performance is
absolutely crucial to me. Does it drive you into your chair with anville-solid bass the way a Max -- and even moreso a
BlockHead -- can? No. But the HD25 still has very good bass extension and good low-frequency control, and certainly enough to keep as much thunder on tap as any other tube headphone amp I've yet heard. And, as good tube amps do, the HD25 provides an ease and airiness in the midband that very few solid state amps can duplicate, as well as percussive timbres that match even the very best solid state amps I’ve heard. The HD25's treble extension is good, though not as extended as the pre-production Twin Head Mark II's was, and shy of the Meier Audio Corda PreHead (Mark I LM6171 version), which is among the most talented amps I've ever heard in this regard. What treble the HD25 conveys (and, don’t get me wrong, there’s plenty to speak of) is excellent -- richly textured, completely grainless. As a whole, the HD25's presentation, from bottom to top, is wonderfully cohesive, and not guilty of any errors of commission that I can hear.
With much of my music listening being jazz (with a disproportionate amount of that being jazz piano trios) and classical music of virtually all kinds, soundstaging and imaging are of paramount importance to me. While not being able to top the Max (and definitely not the BlockHead) in terms of forming tangible, corporeal sonic image objects, the HD25 still does a wonderful job at it, reminding me of the pre-production Twin Head Mark II in this specific capacity. Where it excels, however, edging out all of the solid state amps I have, is in recreating the excited air between instruments, people, walls and ceilings. It’s a slight edge, but an edge nonetheless. Would it top a BlockHead or the pre-production Twin Head Mark II in this area of performance? Probably not, but I don’t think, in such a comparison, it would be completely out of its league at all either.
If you can’t tell by now, I’m mightily impressed with the Eddie Current HD25. And just as important as everything I mentioned above is that all of this performance comes
affordably, ringing up at just under $600.00
shipped. And still there's more: with its three sets of inputs, and line and tape outputs, the HD25 is also a tube
preamp. (NOTE: I haven’t yet tried it as a preamp.)
Simply put, I haven't heard an amp priced at $600.00 or less that sounds better than this one. In fact, I think that its performance should make it a candidate even if you're considering amps at twice its price. So, again,
why on earth isn’t the Eddie Current HD25 one of the best-selling amplifiers in the Head-Fi community?
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Eddie Current HD25: Performing Far Above Its Price
