The Woo Audio WEE Electrostatic Headphone Energizer

Electrostatic speakers have been around for ages. Perhaps you're familiar with the big flat-panel speaker systems from Quad, MartinLogan, Sanders, SoundLab, Audiostatic, Silberstatic, etc. They have potential to sound phenomenal but can be all kinds of picky regarding placement and amplification. Electrostatic headphones have also been around for a long time and have earned a reputation for being exceptionally clear sounding. But there's also a catch - several of them actually.

First is the price: we might say that worthwhile "entry-level" dynamic headphones start around $99, and go as high as $1500 or so at the high-end. Contrast that with Stax where the entry level earspeaker is $420, a midrange unit is $1100, and the top model is $5250. The Stax brand driver units start at $500 and rise as high as $2400, though most serious Stax aficionados use 3rd party models that go even higher in price. So the overall cost of entry tends to be significantly higher than dynamic or planar based systems.

Next comes the confusion of differentiating the models. Experienced Stax users may scoff at this complaint, but it really is confusing for newbies to make sense of the terms "Lambda", "Signature", "Omega", etc which don't really line up with the advertised names of any production model on the market today. Part of this is caused by the fact that Stax has been making earspeakers since 1960 and many of the older models are still in use. This is somewhat rare among headphones, especially compared to the world of speakers. Yes, you still see some Sennheiser HD580s that are nearly 20 years old, and the venerable Sony MDR-V6 is even older. Heck, the Beyerdynamic DT48 is ancient. But generally speaking the Stax models seem to have a unique ability to generate a cult following, and people tend to hang on to them for a very long time. Because of this it is easy to search eBay and become quickly confused by the variety and scope of what is still available. I suggest checking out the current lineup at the Stax USA website to see which models are currently in production. I also recommend the Stax section at Wikiphonia to get some good background information about when each model was made. Stax is certainly not the only manufacturer of electrostatic headphones but most others are out of production. And to be honest for the general headphone population Stax is synonymous with electrostatic headphones, period.

These two issues conspire to keep newbies somewhat intimidated and therefore ignorant of the electrostatic phenomena. This is too bad because people who make the switch to 'stats often remain, never going back to regular dynamic headphones. So clearly it is worth getting past these barriers if at all possible.

Tech Talk
A quick primer on 'stats: they work differently from dynamic or planar magnetic designs. Because of the way they work, they have far higher voltage requirements and thus demand special amplification. In addition to the Stax brand driver units there are options from Woo Audio, HeadAmp, Ray Samuels Audio, and Cavalli Audio, with at least 1 other model (Eddie Current Electra) in the works and some DIY designs (like the eXStatA and Kevin Gilmore's KGSS) floating about.

More choices usually equate to more competition which results in lower prices, but the 3rd party electrostatic amps don't really work that way. Most of them are intended to be flagship state of the art products and have correspondingly hefty prices. The one commercially available exception is the Woo Audio GES which starts at $1450 in basic form and can exceed $2500 with upgrade options. And that's before we figure in tube upgrades. So while it may be cheap as far as these things go, it still isn't what I'd call a budget product.

Stax did at one time provide some low priced options for driving their earspeakers: the SRD series was made from 1960 through 1986. Stax called these units "energizers" rather than driver units because they paired with a speaker amplifier and acted as a step-up transformer to provide the required high voltage. These are available on the used market for affordable prices. The downside is obvious though - the newest of them is 25+ years old, and newbies should absolutely not be poking around inside to make sure everything is in order.


Enter the WEE
Woo Audio took the idea of the affordable transformer box and ran with it. The result is dubbed the WEE for Woo Electrostatic Energizer ($499). It works in the same way as the older Stax units - simply attach a speaker amp (anything with 3 watts per channel or more will do), plug in some earspeakers, and enjoy. The unit has a switch on front for selecting pass-through mode which allows the signal to pass through unmolested to your speakers. This allows the WEE to be easily inserted into nearly any system. The only caveat is that the input grounds are tied together, so bridged/balanced amplifiers should not be used (Pass Labs for example).

The unit itself is very well built and uses an enclosure similar to several of the other Woo Audio amps. Woo is known for their eye-catching designs, and the WEE does look a little plain compared to something like the Woo WA22 with its protruding tubes and transformers, but it's still very well done overall. The size - 12"w x 8.5"d x 3.75"h - allows it to fit easily in most situations. The weight - a healthy 13lbs - is indicative of the substantial build quality.

Woo Audio
5209 Seabury St.
Floor 1
Elmhurst, NY 11373
(917) 324-5284

ultrabike's picture

Very nice review John. Thanks! 

I was wondering how the WEE energizer compares to the SRM-252s STAX basic amp.

John Grandberg's picture

That unregulated wall wart power supply doesn't inspire a lot of confidence, probably chosen by Stax based on price rather than anything else. But I suppose the unit as a whole still does a good enough job.

The nice thing about the WEE is that a user can "tune for flavor" so to speak, by matching it with different amps based on the desired character one is looking for. Like tube rolling, in a way, but more dramatic. 

ls35a's picture

I had one of these.   It sounded .... ok.  And the transformer buzzed.  I finally broke down and bought a 323S amp, it was worlds better. 

I have a friend who tried one as well.  He didn't like it any more than I did.  

A more helpful review would be, 'this is just an ok device, but if you really like Stax Headphones spend the money on a 323'.  

ultrabike's picture

That's a $800 - $1K (~2x) amp though.

What headphone did you use? Also curious about what amp you paired with your WEE. From what John said, results are depedent on the amplifier used.

xzobinx's picture

for  the wee or any stax transformer you need to include the price of the speaker amp which is about 800-1k anw 

John Grandberg's picture

The whole point is that you might already have a killer amp sitting around doing "normal" amp things like driving speakers. Why not tap into that for a Stax setup? If starting from scratch, then yes the price of the amp needs to be factored in. 

I'm not saying the WEE is the ideal solution for everyone. Yet for some situations it would work great. 

John Grandberg's picture

First off, Woo Audio has a 20 day return policy, with a 10% restocking fee. If you just don't like the thing, it's a $50 loss to send it back. If it's got a buzzy transformer I'm pretty sure Woo would replace it for free. Did you contact them about it?

Second, as I mentioned in the review, the result is highly variable based on the amp being used. Not all amps will make a good match, for a variety of reasons. But many amps do and they aren't limited to just expensive amps either.

Don't get me wrong - the 323S is a great bang for the buck model from Stax. It's probably the cheapest way to drive an O2 well - only the 727 beats it in terms of output voltage. But for the Lambda series it isn't my favorite match and I know several folks who agree. Doesn't mean you can't enjoy it but personally I'd rather have a WEE paired with a decent amp, preferably tube based. 

Chiumeister's picture

Thanks for the timely review on the Wee energizer.  I am on a long wait list for the Blue Hawaii.

Did you have a chance to use a top amp with the Wee?

Also, did you match it with a pair of the SR-009 during test?

John Grandberg's picture

No SR-009 or SR-007 used for this evaluation. I mostly stuck with the SR-404LE though I did briefly try an SR-003 in-ear model and an older SR-Sigma Pro. 

I didn't mention it in the article because it was somewhat outside the scope of normal WEE use. But I did have a chance to try it with some PrimaLuna Prologue Seven monoblocks. I'm not sure if that qualifies as a "top amp" though. The sound was really great, probably pushing the limits of what the SR-404LE is capable of. But to be fair, the Consonance integrated (with mid-range Psvane tubes) came very close to matching the PrimaLuna monoblocks for a lot less money. 

ultrabike's picture
John Grandberg's picture

I did link to that thread but you seem to have mined the more important posts from it. So that's very helpful.

It's interesting to note that most opinions go in the same direction when discussing Class D amps versus other types. I'm still not convinced that every "digital" amp will match poorly, but it sure seems to be the trend. 

ultrabike's picture

Here I go, thinking again... Besides speaker amps, could Wee work with some of the juicy-er headphone amps?

This might be a good product to drive electrostats with your Schiit. Valhalla seems 6W per side and it's designed for high impedance cans. Lyr is another one... Not sure though.

Say one had the Cavalli Liquid Glass... Maybe one could Woo-Wee-fy it and have it drive Stax... and in comes primo tube rolling goodness! That said while the LG should deliver 6W into 50 ohms, the Wee seems to be 100 kohms input impedance...

If it works, it sounds cool for the folks that already have these powerful amps for their dynamics and orthos! 

**** EDIT ****


Seems the WEE might couple well with the Woo Wa5 for an all in one solution:


It might be cool if Woo included a ESP950 adaptor as well (they seem to do custom modification of 6 pin normal bias) cool

bobusn's picture

Thanks, John!

Magick Man's picture

If you already own an excellent stereo amp, the WEE is very good, and a solid pairing with all but the higher-end STAX. I've found it's no match for my WES (wouldn't expect it to be) but it isn't that far off the pace of my SRM-717. That's good value for money.

divasson's picture

I have a unit driving a Stax 404, off a Musical Fidelity KW500. Compared with a Stax SRM-313, the Woo Wee is MUCH more dynamic, with better bass and more clarity. You get a top headphone amp for quite a low amount (provided you have a good amp and two cable runs). 

Maybe when compared with top units from Stax, Wee and Ray Samuels, the verdict would not be so clear.

babmusician's picture

have you guys used the wee with a class d amp like hypex ncore/ucd?

Earos's picture

Has anyone tried the Wee with the SR-009?