WooAudio 4 Impressions (pics)

[LeChuck]

Update 11/15/06

I just had my first tube-rolling experience with the Woo Audio 4. I swapped out the stock JJ ECC82's for a pair of RFT's, which I got for ~$60 from the Tube Depot. Just as a side comment about the Tube Depot, I called them before buying and they were very helpful in answering all my questions, and they even shipped via USPS (their regular method is FedEx) upon my request. In all likeliness I'll be going back to them for my future tube needs.

It is difficult for me to offer quantitative opinions on the RFT's vs. the JJ's because I only swapped them once, I'm not really interested in swapping back and fourth twenty times to establish the inferiority of one set of tubes. That being said, when I first swapped in the RFT's the difference was pretty big, more than what I had expected. In past tube rolling experiences with other amps, I would rarely get such a significant change in sound between tubes, sometimes the difference would hang on being placebo. In this particular case, however, the situation is entirely different.

I'm tempted to say the RFT's put the music in a more forward position, but I don't want to imply any kind of collapse of sound stage; a better way to explain the difference is that the music is much more lively, more crisp, and more dynamic.

I'm extremely pleased with the RFT's to this point, and now I'm going to start looking at options for the 6922's, which are currently being filled by JAN-Phillips.

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Until recently I considered myself very much a solid state guy; I was turned off by the extra variable that tubes through into the equation, and I generally felt that they complicated something that should be very simple. While I have heard a fair number of tube amps, the only one I had ever owned and given a serious listen to was the original Little Dot II, and I considered this to be somewhat of a disservice to myself. While this is in no way a negative reflection upon the Little Dot II, my impressions of tube amps were for the most part based on a $150 example, while my solid state amplifiers tended to be in the $1000+ range. So at the end of this summer I decided to take a serious leap into the tube world.

I decided to go with the WooAudio 4, in part because Wei Wu's designs are well respected in this community, and because there didn't seem to be many members with this particular amp and I wanted to try something new. The amp is also a transformer coupled design, rather than OTL, which tends to remove a lot of the tube euphonics - something I didn't have a problem with.

The amplifier's build is top-notch. To begin with, it's both massive in appearance and in weight; when you look at the WA4 you know it's going to suck to carry. The top of the amp features six very prominent transformer boxes, which surround six tubes: 2 x 6C19, 2 x 6922, and 2 x ECC82. The faceplate is very nice and features a big volume knob, a four position input selector, a high/low gain toggle switch, a speaker/headamp toggle switch, and the obvious on/off switch and 1/4" headphone jack. The rear features four inputs along with the amp's speaker outputs. One could probably melt down this amp and build a small car.

As a side story, the amp actually broke within a couple of days of use. When the amp's gain switch was in the high position, the right channel was dead. I contacted Woo Audio about this, and they said it was a very rare defect that the switch would fail. They had me ship the amp back to them, for which they happily credited me shipping expenses, and fixed it within a day. While no one wants their amp to break, and WooAudio assured me they were as surprised as I was about this, it is very nice to know that the company was so helpful in getting this fixed as soon as possible.

I always find it difficult to write impressions without sounding like some kind of commercial, I feel like I only have good things to say, and I worry that I might be misleading people. The truth is I'm usually only enthusiastic about posting impressions of something that I really enjoy, and I enjoy this amp on all levels.

The bass response on the WA4 is huge. When I say huge, I don't mean flabby, out of control, in-da-club bass, but strong, authoritative, and controlled bass. I used to own a Gilmore V2-SE with Blackgates and that amp had more bass control than anything I had ever heard, but it left me feeling there was almost too much control, as if the amp was being so careful in tended to understate everything. On the opposite side of the spectrum, I always felt that the Little Dot II had an offensive amount of bass, it added bass that wasn't there. I would describe the WA4's bass as having the V2-SE's control, but delivering all the bass that was on the recording without leaving you longing for more.

Since I'm talking about the V2-SE here, I have to say that it bled detail. But as I sit here with my WA4, I don't hear any less detail than I did with the Gilmore; every note is just as defined, everything is just as crisp, but only now things are more dynamic and much smoother. The highs and midrange are now so sweet it sometimes makes me unknowingly stop what I'm doing and fall into a trance. The amp presents things in a way that grabs your attention, but at the same time it's easy to listen to for hours - much easier than the V2-SE.

One of my initial concerns was that I would lose some of the separation and soundstage offered by my solid state contenders, the opposite turned out to be the case. I'm not saying my solid state amps had any kind of imaging problems, but it's clear that the WA4 is the superior performer here. The majority of my listening is classical music, and in orchestral works the WA4 effortlessly places every musician in their proper place in space. I consider the "oh, what was that sound!?" test to be a major factor in deciding how I feel about components, and I was having so many of those moments on recordings that I knew intimately well that I was out right shocked.

The WA4 is like tubes without tubes. The amp leaves behind a lot of that euphonic tube sound that many people like, and lends itself to a faster, more aggressive sound, but still keeping some of those important tube benefits like lushness, smoothness, and deep bass.

The amp costs $1200 ($1150 + $50 flat rate shipping), so it's a serious buy. I haven't sat down and compared this to other upper end tube contenders like Singlepower, but I find those amps tend to sound a lot more like tube amps, which is a neutral statement depending on the type of sound you are looking for. I'm pleased on every level with this amp; I feel that I haven't lost anything from solid state, but I've gained a lot from tubes.

I haven't tried the speaker amplifier part of the amp yet. This is primarily a headphone amplifier, with a secondary speaker amplifier ability; Wei Wu recommends efficient speakers with a rating of 95dB and above.

I haven't tube rolled yet, but I just ordered some Mullards and they should be here this week.

My source is a Stello DA100.

Note: Some of you might remember a thread I posted regarding a problem with a buzzing noise. That issue ended up being resolved, and was caused because of my own ignorance. Just need to PROPERLY insert my tubes.

[jamato8]

There is no reason a tube amp should have less soundstage than solid-state. From my experience with amps and from others I have spoken to and corresponded with, tube amps present every bit as big a soundstage and even larger. They also do not have to sound like tubes or anything else but just music. It is all in the implemntation of solid state or tubes that will determine sound. The correct use of tubes or solid-state will yield a musical and enjoyable amp. I think it was in the 70's when solid-state really took over for a while that the notion was put forth that solid-state was better in most respects. With the reemergence of tubes and even LP records, the ear is proving many people wrong that something new was better. Part of the problem was that for a while there weren't that many good tube designers after the fall of the vaccuum tube but with people relearning what was known for 40 years or more, tubes are showing what they are really capable of.

Thank you for the review. I have been curious about this amp. It does appear to be a beast. :^)

[nichifanlema]

That amp is soooooooo beautiful

Well, my woo6 will be in my hand in 12 hours or so...

Just a quick question:

Is Woo4 an upgrade version of Woo2, just like the way Woo6 is to Woo3?

[nichifanlema]

Uh oh..double post..sorry

[DRSpeed85]

******* that thing is pretty!!!

[LeChuck]

Is Woo4 an upgrade version of Woo2, just like the way Woo6 is to Woo3?

No, actually the WA4 is more like an upgraded version of the WA6, both are transformer coupled designs and according to Wei Wu have a similar sound signature. The WA3 and WA2 are both OTL designs, and reportedly sound similar (based on impressions I've read here).

[GreatDane]

That amp screams build quality.

I want one.

[DRSpeed85]

Here's a detail I never thought was interesting; the top cover of the transformer box!!

[F155mph]

So did they tell you what went wrong with the gain switch? BTW that is a very nice looking amp....how much does it weight?

[nichifanlema]

Just a quick question : when you plug in the tubes, do I have to push them in as much as I can?

[GlendaleViper]

Wow. Your pic does more justice to the beauty of that amp than the WooAudio website! I was expecting decent, if plain, construction a la the little-tube designs. This is... much, much nicer.

[GlendaleViper]

Double post. Sorry.

[iomusic]

Originally Posted by nichifanlema

Just a quick question : when you plug in the tubes, do I have to push them in as much as I can?

with my experience, I use my thumb, index finger, and middle finger to hold the bulb of a vacuum tube, and insert it into the tube socket with moving backward and forward slightly, and you feel the tube inserting into the socket completely.

I had listened to the wa4 once, it gave me unforgettable impression! but $1150 is a big number for me.

[SK138]

LeChuck...great review. That amp is sure a beauty. Are you planning on any tube rolling soon? If so...please continue this thread with your tube rolling experience and impressions.

[LeChuck]

Just a quick question : when you plug in the tubes, do I have to push them in as much as I can?

As with any tube amp, you have to make sure the tubes are properly and securely in their sockets. I'm not sure what you mean when you say push them in as much as they can, I don't think anyone would recommend you put your tubes in half way.

At any rate, the tubes are pretty easy to get in and out. Some tube gear keeps such a tight grip on the tubes that you feel as if you're going to rip the tube off it's bass when you take it out, happily that isn't the case here.

LeChuck...great review. That amp is sure a beauty. Are you planning on any tube rolling soon? If so...please continue this thread with your tube rolling experience and impressions.

Definitely plan on tube rolling. I'm looking at ECC82 and 6922 options right now, hopefully I'll have something to roll in by early next week!