ECP Audio L-2 Headphone Amplifier

Editor's Note: I want to personally thank Nate for writing this article. Both he and Doug are long-time headphone DIYers. Both are very competent headphone amp builders. Getting to read Nate's thoughts here is much like opening a little window into the heart of Headphonedom. I am very pleased to present Nate's thoughts on Doug's ECP Audio L-2 parafeed headphone amp. Thanks a bunch, Nate. (Next beer's on me!)

The ECP Audio L-2 Headphone Amplifier ($2495)
I met owner/designer Doug Savitsky (the man behind ECP Audio) long ago through the DIY Audio forum at Head-Fi. We shared a common love of building things and were both passionately involved in the headphone DIY community. It was at CanJam 2010 in Chicago that I got my first glimpse of where Doug's passion was going to be focused for the foreseeable future. At the time he'd made the decision to branch out from simply designing and building DIY projects for fun and have a go at a commercial venture. He had already been working with several designs and had the results along with him in prototype form. Based on the brief audition that I had with two of those prototypes I eagerly awaited the finished product and made a mental note to make sure that I got to listen to them.

Fast forward to late 2011 and ECP Audio's official launch of two headphone amplifiers: the DSHA-1, a fully differential (balanced) solid-state design, and the L-2, a single-ended-parafeed tube design. It has been my distinct pleasure to sample the L-2 for the last few months and in that time I've come to truly appreciate what ECP has accomplished with the L-2 and what an exceptional piece it is. I recently encountered Dieter Rams 10 Principles for Good Design and it struck me that it was the perfect analysis tool for this review. Don't worry, I won't use all 10.

Good Design Is Innovative -- "The possibilities for innovation are not, by any means, exhausted."

I've had the good (?) fortune to go poking around a fair number of commercial headphone amplifiers in my time in this hobby, mostly as a result of said amplifier suffering some sort of failure and me attempting to repair it for someone. What I've encountered in that time is a number of similar designs out there, each packaged by their respective manufacturer in slightly different ways. That's not a bad thing, per se, but it does mean that we as the consumer are not always experiencing the variety of amps we might think we are. In this respect ECP has chosen the road less traveled for the L-2.

The fully transformer-coupled (input and output) spud/parafeed design, utilizing a single 6S45pi tube for both voltage and current gain, is pretty unique and not something that I've seen from any other major headphone manufacturer. But the innovative tech doesn't stop there. Instead of using a typical approach, the L-2 implements modern parts like a shunt-regulated biasing arrangement along with a cascaded MOSFET plate load. Both address typical shortfalls in tube amplifier design that date back the better part of century. The over-arching premise here is that headphones are particularly sensitive and that noise introduced by the amplification stage is a direct detriment to successful performance. I agree, and to that end ECP has done a fantastic job with the L-2. I've used it with both closed and open headphones of varying impedances and sensitivities, and the claims that are made on ECP's website are accurate--flip the on switch and you are greeted with precisely nothing. Big plus up for the L-2, but wait, it gets better.


Good Design is Aesthetic -- "...well-executed projects can be beautiful."

The L-2 is, quite simply, beautiful. Some will call it plain, or perhaps industrial, but the approach that ECP has taken is extremely well executed. Buyers are permitted a choice of several exotic hardwoods for the side panels and the rest of the chassis is tastefully brushed aluminum with not a hint of bling save for the ECP badge located front-center of the top panel. I'd call the overall look "understated elegance." But rest assured, the beauty is not skin deep. I've had a peek under the hood and the care with which the circuit was arranged is evident. From the Lundhal input transformers, through the V-cap coupling caps, all the way to the custom designed Electra-Print output transformers, the L-2 is as pretty (to this nerd's eye anyway) on the inside as it is on the outside.

The power supply is a somewhat more utilitarian enclosure, constructed entirely of anodized aluminum with the power umbilical connection on the front and the IEC inlet around back. It also possesses the signature ECP badge on the top panel, which is a nice touch that ties the two pieces together. ECP refers to its products as craft-made and this should not be viewed as a sacrifice or compromise. If anything the build quality evident in the sample unit I was provided is easily the equal of any commercial product I've come across.

ECP Audio

jherbert's picture

And actually, are they suited for anything else then GRADOS? Just wondering.

Willakan's picture

My immediate concern would be the price rather than what they are designed to drive. Would be nice to have at least a couple of basic specs for your two and a half grand...

Any chance of future measurements? :D

n_maher's picture

Sorry for the lack of measurements guys, neither I nor Innerfidelity is currently setup to perform the full spectrum of measurements. It is something Tyll is working on. What I can provide is what the manufacturer gave to me:

Test Constraints - Load: 32ohm, Output: ~125mW (2Vrms)
Results - THD: ~0.14%, IMD: ~0.12%

I'll see if I can get the full suite of RMAA results from ECP and find a way to post them here. It's worth noting that in the test listed above you'd be deaf if you were actually listening that loud and the results are still very good.

Regarding how the amp might perform with headphones other than Grados. Given the configuration, which has selectable output impedance, I'd say the amp should perform well with a wide range of headphones. It has characteristics that should allow it to succeed - extremely low noise floor, selectable output impedance and sufficient power to drive all but the most extreme dynamic headphones.

About the price - yes, ~$2500 is a lot of money. The L-2 is neither the cheapest or most expensive amp in this category. Do I believe that it's a good "value"? Yes. It is extremely well built, well designed, not stuffed into a cookie cutter enclosure and backed by someone who'll provide excellent customer service. For example: Doug contacted me mid-review to let me know that he was completely redesigning the power supply. He had noted, in a few examples, that there was what he deemed to be an unacceptable level of mechanical noise from the transformer. Not content with good enough he designed a new circuit board for the power supply and had new, custom wound transformers produced. It's that kind of effort that shouldn't go unnoticed or unappreciated. That said I don't expect that everyone can justify this type of purchase but for those considering an investment of this magnitude it's a worthy option.

Tyll Hertsens's picture
... at how long it's taking to get measurement routines together. :(

Anybody know where I can buy some time?

Limp's picture

I usually stay well clear of amplifier reviews, but this one was well worth the read. Good job Nate.

No doubt some measurements would be interesting on an educational level, but I wouldn't expect anything revolutionary in the way of transparency. Tube amplifiers are often designed with other goals in mind.

I just got to say that this is one of the best looking amplifiers I've ever seen. TTVJ/Millett could learn a thing or two from Doug, I think ;)

Willakan's picture

Thanks for the specs: seem somewhat typical for a SE amp, although I really did expect higher output power: with orthodynamics all the rage recent designs seem to go vastly overkill on that front (6W into 32 ohms! Acheive 130db peaks!), but this is genuinely ill-suited to driving orthodynamics IMHO. As you say, that wasn't really a design target though...

As someone from the Audio Critic school of thought when it comes to audio reproduction, I don't feel my extended opinions on expensive SE amps would be very constructive, so I'll just say: nice review (and comment on how damn nice that casework is)!

Limp's picture

Peter Aczel, yay!

teufelshunde's picture

I can speak from first-hand experience that Doug's amps work well with both Audeze and Ultrasone phones. We already know that they're great with Grados.

I recently flew to Chicago to audition Doug's amps for use with Audeze LCD-3s; and I came away thinking that both the L-2 and DSHA-1 showed superb synergy with Audeze's phones.

I brought some Ultrasone Pro900s along just for giggles, and they were easily driven to listening levels that transcend discretion.

I ultimately purchased a DSHA-1 because of a personal preference for SS topology (I don't know jack about tube rolling).

I have the front switch on the DSHA-1 set for hi gain; but with the volume control only set at the 9 o'clock position, the output levels are more than loud enough for my '50 something' ears when listening to classical, jazz, hard rock or dub step.

zippy2001's picture

What a great review Nate!
It was enlightening and not too much technical detail to get me lost in the design details. It made me want to give this amp a listen.
It looks great and I would love to hear one at a future meet.

swt61's picture

A straightforward, no BS review. Well thought out and well written.
I was also impressed with the prototypes presented at CanJam 2010.

ECP audio seems to be old school in as far as their reason for being...passion!

purk's picture

I just want to add that the L2 is a match made in heaven for the HD800 as well. The combo sound sweet and very liquid through out the range. The HD800's treble energy is tamed down by the ECP L2 so it is very easy on the ears. Bass is tactile with good sense of low level details. Super quiet background. Easily one of the best amp around for the HD800 (if you are lucky enough to find one used!).