Woo Audio 4: A Brief Re-review (upgraded)

Sep 20, 2007 at 11:37 PM Thread Starter Post #1 of 14

LeChuck

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Introduction

To begin I have to apologize for adding to the Woo Audio fire. Lately threads and posts concerning Woo Audio amps seem to be popping up on a daily basis, which I certainly don't view as a bad thing, but I know that some of you might be getting a little tired of the hysteria.

I took delivery of the original Woo Audio 4 about 10 months ago, in October 2006. I wrote my initial impressions, and posted a few pictures which you can check out here: http://www.head-fi.org/forums/showthread.php?t=207234

A little while ago - I'm not sure exactly when - after the Woo Audio 6 craze hit Head-Fi, some members started to experiment with capacitor upgrades, and many of them experience very favorable results. It progressed to the point where Jack Wu began to officially offer upgrades for that particular amplifier, which could be built in during its construction. While I was intrigued by the upgrades, I was quite satisfied with my own amp and never pursued the upgrade bath beyond tube-rolling.

It wasn't until this August that I contacted Jack and asked him about upgrade possibilities for the Woo Audio 4. Among a number of Blackgate and V-Cap capacitor upgrades, Jack said the amps topology could also be significantly modified to make it headphone-only, which he said would also noticeably improve performance. While the amp was always designed primarily for headphone use (it's speaker section can only drive highly efficient speakers), Jack said the headphone-only conversion would completely optimize it for that purpose.

I asked Jack what he thought about a maxed out headphone-only version, with V-Caps and Blackgates. He had actually built one such amp, and had this to say about it:

"In brief, the newer version offer the fastest speed among all other models we build. This version has better dynamic, separation, and bigger soundstage than the previous builds." -Jack Wu

So I sent my amp off to Woo Audio!

Preamble/Disclaimer

I obviously do not have a stock WA4 to compare my upgraded version to, so these impressions will be inherently subjective. I try to be as reasonably as I can, but alas this is not a scientific examination. Also, there are people here who are much better audiophiles than I am, so my descriptions and lexicon might not be the very best. There are adjectives people use here to describe how music sounds to them, and I really have no idea what they mean, so I try to stay away from anything ambiguous. I might be using words in the wrong or untraditional context, so I have to apologize up front. Hopefully what I mean to convey will be self evident.

I have absolute pitch and studied classical piano for a large part of my life, but I freely admit I do not hear certain things. Differences between power cords, interconnects, component burn-in (except in a few examples), all illude me. With that in mind, I can't offer any opinion on those things, and some of you might find my descriptions lacking in detail.

Finally, I love this amp. I loved it before the upgrade, and I love it even more after. I generally don't keep gear I don't like, and I usually don't take the time to review it either. I make an effort to avoid sounding overly preachy, but know that this review will be highly positive.

Impressions

If I were to chose a few words to describe how the upgraded WA4 sounds they would be: powerful/authoritative, smooth, clear, deep, heavy, fast, separation.

I'll start with the last one: separation. I generally consider something to be legitimately improved, or at least changed, if you listen to a very familiar track and hear something previously unknown, or it catches your attention because it sounds different. I start to question myself if I'm straining to hear differences, and can't reliably discern them. There was certainly no straining with the WA4; as soon as I plugged it in and started listening to a few old and familiar tracks, I was immediately experiencing "what the hell was that, I need to rewind" moments.

I would have said that my old V2-SE had a slight edge over the stock WA4 in terms of separation, but the upgraded Woo far outdoes the Gilmore. There are notes on tracks that I've heard thousands of times, coming out like I have never heard them before. I really can't emphasize enough how taken back I was by the separation and clarity of each sound. Complex and layered music is breezed through.

51peWUz2VYL._AA240_.jpg

The 1981 version of Gould's Goldberg Variations taken from the analog masters (the original release was done on inferior digital equipment), is a great recording. To illustrate what I was describing in terms of separation using this album, the key strikes are so sharply defined and clearly cut out, it feels like a key was hit in front of your head.

The WA4 is an absolute powerhouse of an amplifier, which I think is necessary when driving the HD-650's. The Woo dominates the Sennheisers into total submission, it drives them almost laughably. I hardly venture beyond 13 O'clock on low gain. That being said, the amp was delicate enough to drive my Shure E500's in a way that my portable can only dream of.

Notes are heavy, impactful, and authoritative. This ties in with the separation in that not only are things clear and distinct, but they're bold and full of body.

Speaking of impactful, the bass on the upgraded WA4 is nothing short of epic. And to be sure, I don't mean that in the sense that it's bottom heavy, or that it's warm, because it's none of these things. What I mean is that it delivers serious bass on par with the power that it delivers the entire frequency range. The bass is like a marble statue: heavy, carved out to the finest detail, and impenetrable.

A few bass gems like the opening of Strauss' Also sprach Zarathustra, The Alan Parsons Project's The Raven, or Radiohead's Everything In Its Right Place, were sending low frequency chills down my spine. It was mesmerizing.

There's also an airiness, or sparkle to the highs. They're very smooth, yet very crisp. I'm not trying to contradict myself here, but I just want to say that the highs oozing sharpness and definition, but there's not fatigue or harshness associated with them. In fact yesterday while doing a project and listening to Paganini's 24 Capricci I found myself in a daze for nearly 15 minutes before I looked at the clock and realized I had just been sitting there mesmerized doing absolutely nothing.

Final Thoughts

In my mind the biggest improvements are in separation, speed, dynamic impact and punchyness, bass, and detail. This is by no means an all inclusive list, and I would probably go so far as to say the amp is totally improved (and it does measure better), but I won't reach for a million words to say essentially the same thing: the upgrades are significantly noticeable.

I'm extremely pleased. I mentioned earlier that I was pleased before I even decided to upgrade, and really never felt the need to, but asked out of curiosity. Now I'm glad that I did.

One interesting thing about the upgrades is that when I turn the amp off now, it will continue playing music of almost a minute before it dies out.

A few negatives:

1. The amp runs very hot. And because it's so big, it puts off a lot of heat. This thing could double as a space heater.

2. It's huge. Not really a problem for me, and I actually enjoy its massive presence, but some people might not want a 35 pound amp.

3. Woo Audio builds a ton of great amps, and now many of them have upgrade options. Jack is more and more willing to customize amps, which is a great thing, but it can almost make choosing an amp more and more difficult. Singlepower, for example, offers really not "standard" setup, virtually every amp they make is built to order, and I sense that Woo Audio is moving in a similar (maybe less extreme) direction. These new options and models are exciting, but can be overwhelming, and make it difficult to discern differences.

Overall, however, Jack and Woo Audio are a class act and make incredible products with incredible build quality, performance, and value.
 
Sep 20, 2007 at 11:54 PM Post #2 of 14
I corresponded with Jack about the Black Gates starting a couple of years ago and the Vcaps more recently suggesting their use. I am glad both have had an important impact to the sound quality. I find it exciting what they can do for audio.
 
Sep 21, 2007 at 12:17 AM Post #3 of 14
Quote:

Originally Posted by jamato8 /img/forum/go_quote.gif
I corresponded with Jack about the Black Gates starting a couple of years ago and the Vcaps more recently suggesting their use. I am glad both have had an important impact to the sound quality. I find it exciting what they can do for audio.


Yes I remember you were the first to get it done... your black WA6 right? I think he uses your amp in his pictures.
 
Sep 21, 2007 at 12:44 AM Post #4 of 14
No that is not my 6, I corresponded and recommended the use of Black Gates and Vcaps and once they were tried and Jack got good feedback it became part of the upgrade policy. I did do the modification on the Woo 3 with Black Gates a couple of years ago, which was the starting point for recommending them to Jack. I have used BG's for years. One thing to remember if you bypass them with another cap, only use BG's for that purpose.
 
Sep 21, 2007 at 1:10 AM Post #5 of 14
My WA6 was the first to be built with the Black Gates & V-Caps (per Jamato8's recommendation). My amp has about 500 hours on it now. I just completed about 100 hours burn-in on my new SAA Equinox LE cable and I must say, this amp has amazing clarity/resolution. I have been in the audio hobby for over 30 years now, and this is the first setup that I have ever had that allows you get to the heart and soul of the music. It's really hard to put into words, but it's like the equipment is not even there... just the music!
 
Sep 21, 2007 at 11:13 AM Post #7 of 14
Many thanks for the great update on the upgraded WA4. I truly believe the WA4 deserved better recognition, and even in stock form, is one major step up from the WA6.

As a happy WA6 owner, I almost walked down the WA4 path. I started talking to Jack about maxing out my WA6, but that don't last very long. It turned out I started a long discussion with Jack on my next ultimate headphone amp. Jack proposed a headphone amp version only of WA4, maxxed out, and the discussion later evolved to a new model called WA-X, a hybrid derivatives of WA4, which is essentially a totally redesigned amp using the WA4 topology but different tubes, different layout...and feature set.

It was at that point close to a "freeze" that I realise my new, yet-to-be-born baby will cost close to a headphone amp version of WA5.... and from that point onward the decision went downhill, and now I am finalising with Jack on my full feature, maxxed out WA5.... a 80lb two bodied beast.

What a journey !

F. Lo
 
Sep 21, 2007 at 4:31 PM Post #8 of 14
what a great "re-review"! made me want to get in line for a wa-4 and mod it
at home...but listening to my modded wa-6, i'm satisfied at the moment to
stay where i am...these blackgates and v-caps are incredible stuff. i'm hearing
improvements in SQ even now, after 500+ hrs. of burn in...i can just imagine
how the modded wa-4 sounds with its high-end topology...
 
Sep 21, 2007 at 4:34 PM Post #9 of 14
With both the V's and the BG's you can still hear changes, for the good, at over 800 hours.
 
Sep 21, 2007 at 5:36 PM Post #10 of 14
Quote:

Many thanks for the great update on the upgraded WA4. I truly believe the WA4 deserved better recognition, and even in stock form, is one major step up from the WA6.


This is the unfortunate truth. I always wondered why Jack's higher end amps were never adopted as readily as the WA3 and WA6. I realize price is an issue, but there can't be more than two or three people here with a WA4.

Quote:

With both the V's and the BG's you can still hear changes, for the good, at over 800 hours.


One I hit about 400, and then 800 hours, I'll come back and update things with impressions. I obviously won't be able to objectively compare, but I will offer my developing thoughts on the amp.
 
Sep 21, 2007 at 6:27 PM Post #11 of 14
Quote:

Originally Posted by LeChuck /img/forum/go_quote.gif
Woo Audio builds a ton of great amps, and now many of them have upgrade options. Jack is more and more willing to customize amps, which is a great thing, but it can almost make choosing an amp more and more difficult. Singlepower, for example, offers really not "standard" setup, virtually every amp they make is built to order, and I sense that Woo Audio is moving in a similar (maybe less extreme) direction.


i think this is accurate. before i committed to buy an apache i inquired about a balanced amplifier from woo audio, asking if he had any plans to release one as part of his standard line. he said no. but that he could build me one - a custom design. we traded a number of emails for a while and i was actually very close to committing when he said that the design needed to be looked at again and would take much longer than expected. so i got the apache. but i fully expect to see someone with a custom made woo audio balanced amp in the near future.
 
Sep 22, 2007 at 3:22 AM Post #14 of 14
Nice review! My WA5 just returned from a visit to Woo Audio for v-caps. Hopefully Jack will have the WA4 at the National in May. I don't remember seeing it in San Jose. I would love to check it out.
 

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