Wonderful Woo Audio WA5 300B Single-ended Triode Class-A Speaker and Headphone Amp.

[Steve Hoffman]

Way back at the Head-Fi show three years ago I met Jack Wu. Earlier in the year, Jeff Dorgay, publisher of TONE AUDIO had given me a WooAudio 3 - Single-Ended OTL, Class A Vacuum Tube Headphone & Pre Amplifier to try out with my new Cans. I dug it and when Jack introduced himself at the show, I was mighty pleased to meet him and told him so. I love a company that is nutzy over vacuum tubes and will find any way to utilize them in their products.

http://www.wooaudio.com/

Jump ahead to last year and the headphone show at the LA airport area where Joe Harley and I gave our Blue Note Music Matters lecture. I met the entire Wu family and it was arranged that I hear their new WA5 300B Single-ended Triode Class-A Speaker and Headphone Amp (see pictures below).

Now, let me say right here that the Woo amps are built in NEW YORK CITY, UNITED STATES OF AMERICA (in case anyone had any doubts). Jack's father Wei is the designer and Jack's brother Zhidong helps with the handcrafting of each amp. As you can see by their product line on their website, they have many wonderful products for headphones but the WA5 is special to me because it has enough juice for use as a single-ended speaker amplifier.

Jack offered to build me a special WA5 (with many parts upgraded as you can see on this page: http://www.wooaudio.com/products/wa5.html ) and I jumped at the chance to hear what Woo Audio could do in the world of single-ended 300B amplifiers.

All WA5's are built to order over a five-day period (there is a waiting list). This is not a mass produced product. As you can see, their product line is reasonably priced for the hand-built quality you get.

Now, please note and I'll shout this as well: NO PRINTED CIRCUIT BOARDS ARE USED AND THE WIRING IS POINT TO POINT. I love that. I was told even the friggin' output transformer (which is usually outsourced) is designed and prototyped by Wei Wu.


Woo amplifiers are ONLY sold directly on the company's website (see above links).

WooAudio doesn't care if you tube swap in fact (unlike many other companies) they love it if you try out different tube types both new and vintage. I have mixed and matched old and new and really like the tube combination I have spelled out below.

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Now, before I talk about the sound in this mini-review, a few technical details. The WA5 is two pieces. First piece has the power supply on the chassis and the other is the amplifier. Both measure 8 1/2 x 9 x 17 inches.

You can use headphones with a rating of 70 ohms or higher (in the "high" jack) and the "low" jack is for cans with less than 70.

Now as you can see by the open design and big old tubes, the unit contains HIGH VOLTAGES! So keep this sucker away from children and animals. They could get burned.

I love the beautiful standard brushed silver finish chassis (but there is also a black finish available). I dig the build quality. I'm telling you that the build quality of this thing is DEFINITELY on par with top of the line amps that sell for MUCH more money.

Here is what you get in the standard version for your $3,150.00:



Color Black Silver * AMP and PSU ship in a molded foam within a wooden crate
* Power supply umbilical cord is included.

* 1 pair of 300B, 6SN7, and 2 tube rectifiers are included.

* AC Power cord and RCA interconnect cables are NOT included.

* Shopping cart applies to the U.S. buyers only. International buyers please contact for shipping cost and payment instruction.

Technical Specifications:
•Two 300B power tubes
•Two 6SN7 drive tubes
•Two 5U4G rectifier tubes
•Voltage: AC 110/220V, 50/60 Hz
•External dimension (each): 8½(H), 9"(W), 17"(D)
•Weight: Amp Unit: 35 lbs, Power Supply Unit: 40 lbs
Headphone Amplifier Specifications:
•Headphones impedance : 8-800 Ohms
•Frequency response: 10 Hz—60 KHz, -2dB
•Power output >= 1.5 watt
•Signal/Noise: >= 95 dB
•THD: <= 0.08%, 1Khz
Speaker Amplifier Specifications:
•Power output: <= 10W x 2, THD <= 3%, 1Khz
•Frequency response: 16—38 Khz, -2dB
•Output impedance: 8 ohms
•Signal/Noise: >= 90 dB

Standard Features:
•Independent headphone and speaker circuits
•High-end output transformer design
•Point-to-Point wiring
•Selectable speaker, AKG-K1000, high and low impedance dynamic headphones output switch
•One 1/4" headphone jack and one XLR connector for K1000
•Four pairs of gold-plate RCA inputs
•Selectable inputs switch
•Two pairs of gold-plate speaker terminals

Got it? Good. Most of you know how much I love the sound of the old 300B amplifier tube. The vintage Western Electric versions of this tube were so reliable that they were the tubes that were sunk to the bottom of the Atlantic Ocean to amplify the transatlantic phone cable back in the 1930's. The tubes lasted forever (a good thing if they are at the bottom of the ocean) and have that perfect sound.

Now they made my version with the Premium parts upgrade:

Parts upgrade: $1100
Premium parts upgrade package.
(Parts upgrade are intended for amplifier purchase, not to be sold on a standalone basis.)


We carefully selected the best possible audiophile graded parts that bring the ultimate performance from the amplifier.


•V-Cap input coupling caps. Matched pair 0.15uf/600V
•Jensen voltage filtering caps, 220uf/450V
•Blackgate bypass (6SN7 cathode) caps, 220uf/160V
•Blackgate bypass (6SN7 cathode) caps, 220uf/16V
•Blackgate bypass (300B cathode) caps, 470uf/160V
•Mills load resistors (300B), 750 ohms, 50W
•Mills load resistors (6SN7), 22 kohms, 12W
•Mills cathod resistors (6SN7), 7.5 kohms, 5W
•Kiwame cathod resistors (6SN7), 330 ohms, 2W
•Kiwame cathod resistors (300B), 330 kohms, 2W
•Jensen decoupling caps, 100u/500V


I also told Jack I wanted to try this new 300B that I heard about and he gladly upgraded for me like so:

Power tubes upgrade 1:
Shugang 50-Years Treasure 300B matched pair. $600 with 12-month warranty, sourced from Grant Fidelity

These are incredible detailed, excellent image, great speed, lush mid range, extended high end, and yet the most authority bass a 300B can produce. Indeed, the Treasure 300B is one of the most favorites for the WA5.

The Treasure series is a statement work of Shuguang's 50-years' of expertise in vacuum tube design and production, a highest quality build. Its unique black glass is due High Polymer Compound Carbon (HPCC) coating. Compared to traditional carbon spray technology, HPCC coating will allow greater concentration of electrons, enhance and maintain stability of the electron flow, maximize "secondary electron emission suppression" from the glass enclosure, in turn reduce effects of electron swirl which generates internal noises from the vacuum tube itself.

The tubes sound great and can really hold their own with other current 300B's out there. In fact they are my current (pun intended) favorite!

Another upgrade I asked for was the rectifier tube. I had heard the Sophia 274 before and learned that Jack Woo liked it as well:

Rectifier tubes replacement:
Sophia Princess Mesh Plate 274B rectifier. $300 (2 pcs) with 30-day warranty
To impact WA5's sound quality or for your super backup. Buy and ship independently.

Sophia Electric™ 274B tube is a premium rectifier tube for a 5U4/5R4/5AR4 direct replacement with 3X longer plate structure, thus it has a deeper, wider sound stage and even smoother sound than Mullard 5AR4.



So, after about 2 hours of burn in I couldn't wait any longer. Had to try the new Woo out. First I tried it with my two headphones:

Sennheiser HD-600 headphones with Stefan Audio Arts Equinox cable upgrade
AKG K-701 headphones with Ken Ball ALO Audio upgrade


Ah, wow, amazing sound from the cans. I could feel the upgrade. It made listening on phones a much more sensual thing and I am usually not much of a headphone listener, preferring trusty speakers.

So, with great anticipation of a great 300B sound coming out of my Belgian Venture Audio GRAND EXCELLENCE speakers I switched over to "amp" and hooked up some neutral sounding Audience bi-wire speaker cable, plugged everything in to my main system and fired away. First of all, since the Woo has a volume control, I could eliminate my preamp from the equation and just concentrate on my McIntosh MCD500 digital player into the Woo into the Ventures. A clean connection.

Let me state right here that I did not and do not expect a 10 watt receiver to move mountains on my gigantic Venture speakers. What I wanted to hear was a magic midrange, full, lush sound and that 3-D impact that single ended 300B amps can deliver. I wanted this sound but not the $20,000.00 price tag that goes with it! The Woo WA5 delivered.

Other amps can sound two-dimensional and flat. Some solid state and tube amps can sound too mellow, too lean, too whatever but an amp that uses 300B tubes better damn well sound holographic or there will be hell to pay. I don't care what kind of hard to drive speakers you are using in your system, when you use a low powered 300B single-ended amp you should be able to instantly HEAR THE MAGIC.

Once hooked in I put on my Nat "King" Cole DCC Compact Classics 24 karat gold disk of LOVE IS THE THING and let it rip. Ah, resurrecting the dead, Woo style!

I tried BTO and "Takin' Care Of Business" to hear that low bass and how it "swung" down there with only 10 watts. It sounded deep, even and only a tad underpowered which was not unexpected.

I still have my big Venture speakers hooked up to the Woo so I can have that "YOU ARE THERE" sound for a while longer...


Now, folks, with GIANT speakers that are used to at least 50 watts, a small 10 watts is not going to drive the volume to ear-shattering levels so don't try. But on speakers that are easier to drive (like my vintage 15" Gold Tannoy Lancasters) you can blast the Woo WA5 as loud as you want and it's like you're back in the past, dancing with Benny Goodman or watching Nat Cole, Billie Holiday and Frank Sinatra singing right in front of you. I love it!

So, there you go. You get holographic 300B sound either for your headphones or your speakers. This is so cool as most every 300B amps (even the $50,000.00 ones) do NOT have any headphone jack whatsoever!


I think it's a great deal for those of you who want amazing sound, hand-built premium quality, made in America reliability and a beautiful two-piece audiophile showpiece to enjoy your music collection with.

Thanks for reading. Here is the Woo Audio WA5. Notice the neat way the two units are packed. Impressive, yes? Take a look:

[Claus]

Beautiful design....

Maybe a perfect match with Sennheiser's HD800.

[Raylinds]

I have been using a Woo Audio WA5 with all of the upgrade for about two years now and couldn't be happier. They are driving a pair of Paradigm speakers, and the sound is magnificent with my VPI Aries 3 TT. The Wu's are great people to work with, and provide great service.

Steve,
I am currently using the reissue Western Electric 300B tubes, did you compare these to the Treasures?

[TigerMMG]

Wow... I am drooling now...

[Steve Hoffman]

Originally Posted by Raylinds

I have been using a Woo Audio WA5 with all of the upgrade for about two years now and couldn't be happier. They are driving a pair of Paradigm speakers, and the sound is magnificent with my VPI Aries 3 TT. The Wu's are great people to work with, and provide great service.

Steve,
I am currently using the reissue Western Electric 300B tubes, did you compare these to the Treasures?

It's amazing what 10 dinky watts can do, isn't it? Of course, as they say, it's the FIRST watt that counts.

I didn't try my reissue WE 300Bs in the Woo. I have those in my Wavac unit. I'm sure they do sound wonderful in there. Isn't it amazing that so many current versions exist of a tube that was rendered obsolete over 70 years ago? And all of them have a good 300B type sound. Thank the Asian audiophiles who worshiped Western Electric way back when we had written single-ended off 300B amps off (around 1935!) for that rebirth.

On the other hand, have you looked on eBay or with tube sellers at the price of NOS vintage Western Electric 300B's these days? Yikes. People thought I was crazy when I paid $85.00 each for 38 new old stock etched base 1939 Western Electric 300B tubes in original boxes back in 1989 (thanks, Steve M.) when I had no amplifier to even play them on. Now I could buy a mansion with swimming pool and tennis court with the money if I sold them at current value..

[Raylinds]

Originally Posted by Steve Hoffman

On the other hand, have you looked on eBay or with tube sellers at the price of NOS vintage Western Electric 300B's these days? Yikes. People thought I was crazy when I paid $85.00 each for 38 new old stock etched base 1939 Western Electric 300B tubes in original boxes back in 1989 (thanks, Steve M.) when I had no amplifier to even play them on. Now I could buy a mansion with swimming pool and tennis court with the money if I sold them at current value..

Warren Buffett would turn green with envy!

[Mike in MD]

Great review Steve, I would love to have that sitting on my rack.

[kevinsinnott]

I've got a lowly 300B amp, an Audio Electronic Supply SE-1 (Cary's budget line). I can only imagine how great the Woo Audio amp sounds. I am convinced of the 300B tube's greatness every time I listen.

Thanks for the review, Steve. I've followed your comments regarding headphones over the years. You compliments take on greater significance knowing your preference for loudspeakers.

[MilesSmiles]

I like the design.

[TigerMMG]

I just took a look... $1000 a tube?!

[Steve Hoffman]

Originally Posted by TigerMMG

I just took a look... $1000 a tube?!

?? The NOS (new old stock) tubes are quadruple that price!

[TigerMMG]

Western Electric 300B tube on ebay... about $1000 each. There is a guy selling a pair used for $2500.

[Solitary1]

Their headphone amps have been on my wishlist forever. They absolutely gorgeous equipment.

[TigerMMG]

Originally Posted by Solitary1

Their headphone amps have been on my wishlist forever. They absolutely gorgeous equipment.

With what Steve wrote... I am really tempted to buy an amp from Woo... I don't have much use for headphone amp... maybe I can score an used Woo Audio amp.

[John Sanders]

Beautiful design.

[Baron Von Talbot]

Pair-fection :-)

[YarGnawh]

Awesome review Steve!! Glad you enjoy the amp. I also use the Sennheiser HD-600 and the AKG K-701 on my WA5. I upgraded my tubes a while back to the Shugang 50-Years Treasure 300B + Shuguang Treasure CV181-Z / 6SN7GT + Sophia Princess Mesh Plate 274B which is the perfect combination!! Finally, Jack Wu is always a pleasure to work with!!!

[Tony Plachy]

These are beautiful, would love to hear one of them, if head-fi is ever near here I plan to check these out.

[Steve Hoffman]

Originally Posted by YarGnawh

Awesome review Steve!! Glad you enjoy the amp. I also use the Sennheiser HD-600 and the AKG K-701 on my WA5. I upgraded my tubes a while back to the Shugang 50-Years Treasure 300B + Shuguang Treasure CV181-Z / 6SN7GT + Sophia Princess Mesh Plate 274B which is the perfect combination!! Finally, Jack Wu is always a pleasure to work with!!!

It's always nice to know the face behind the product. Good people...

[LeeS]

Looks like very well made gear.