November 2005

WAVAC MD-805m Monoblock Amplifiers
A crystal palace for your music.
Review By Wayne Donnelly

  The WAVAC family of tube electronics from Japan is widely recognized for fabulous cosmetics, no-compromise build quality, glorious sonics, and — inevitably, given their design approach — very high prices. This writer has previously had the pleasure of reviewing the company's EC-300B and MD-300B stereo amplifiers, driving very high-efficiency loudspeakers appropriate to their 10 Wpc power output. The MD-805m monoblocks' 55-Watt power offered a chance to evaluate the WAVAC approach to amplification with a wider range of loudspeakers, and I jumped at the opportunity to try them out.

WAVAC offers an unusually large selection of amplifiers, based on numerous output tubes and ranging in price from around $7000 up to $350,000! The basic characteristics of the line are consistent throughout: all are Single-Ended Triode (SET) designs running in pure Class-A mode. All use WAVAC's proprietary IITC (Inverted Interstage Transformer Coupled) architecture, and all incorporate ultra-wide-bandwidth Tango transformers.

First Look
At a bit over 40 lbs. each, these amplifiers are dense little nuggets.  The chassis enclosures are exceptionally rigid and acoustically dead. The top plate is a 10 mm-thick aluminum, which provides a resonance-resistant platform for attaching circuit components.

The sculpted fascia, nearly an inch thick on the left side, holds the familiar large WAVAC power-on button and power LED, as well as a volume control knob. The inclusion of the passive volume control allows the owner of a single-source system to connect, say, a CD player directly to the amplifiers without need for a preamplifier.  Within a more conventional setup, the volume knobs allow the listener to "trim" channel balance if the system preamplifier has no balance control, as is commonly the case these days.

The three tubes of each chassis are exposed on the front half, surrounded by a heavy glass screen. The transformers are behind the tubes in a sealed protective enclosure. The IEC input, 4- and 8-Ohm loudspeaker terminals, and a single RCA input jack are located at the very rear of the top plate — a thoughtful choice that facilitates connections using thick and less-flexible audiophile cables.

Functional Highlights
The robust 805 power tube allows these amplifiers to deliver a solid 55 Watts with only a single output tube per side. WAVAC suggests that this kind of minimalist design offers better performance and more SET "magic" than parallel SET designs using multiple output tubes to get higher power output. The 4 Ohm and 8 Ohm speaker output taps offer greater flexibility and excellent sonic performance with a broader range of loudspeakers. The MD- 805m drives 4 Ohm speakers with aplomb — a rare ability among SET designs.

The IITC circuit completely eliminates capacitors in the signal path.  In particular, DC ignition of the filament contributes materially to the amplifiers' excellent S/N ratio.  In addition to the heavy-duty chassis, anti-resonance measures include isolation of the tubes and transformers from the chassis with elastomers In order to reduce tube microphonics and transformer vibration.

Notes for Tube Rollers
In my previous WAVAC reviews, including the magnificent PR/T1 line stage, I found that the essential neutrality of the circuits made sonic changes resulting from substituting different tube immediately and clearly audible. I had originally planned to do a good bit of tube-rolling for this review, but circumstances dictated differently. This review sequence was unusually lengthy, being interrupted by a four-month hiatus caused by my relocation from California to Chicago. Not having lived in the Windy City for some 25 years, I have not yet established a full complement of audio buddies — including tube enthusiasts with good stuff to lend — as I had on the west coast.

The tubes provided with the MD-805m's by Jim Ricketts of WAVAC distributor tmh Audio proved to be excellent:

    Input: NOS GE 5751 (12AX7 type)

    Driver: NOS GE 6Y6GC

    Output: New production Chinese 805

Jim Ricketts also sent a note with several suggestions, which I am including here for reference by interested tube rollers"

"With respect to input tubes, listener reports and my experiences indicate superb results with other 12AX7 types, including Mullard ribbed-plate and Mullard CV4004 box-plates for that gorgeous Mullard midrange. For a more neutral & clean sound, we have had great results from Telefunken ECC801S and NOS Tesla grid-frame types. Since tube tastes are subjective, any high-quality 12AX7 type that an owner prefers would work well and provide that last bit of fine tuning. The NOS GE 6Y6GC is a superb driver tube; no need to experiment. They are widely available for under $10 each, and they last a very long time. The Chinese 805 tube is well made in a ISO9001 factory [which indicates stringent quality control standards] and provides excellent sound."

Just to verify my assumption that these amplifiers would match the typical WAVAC sensitivity to tube differences, I did make a couple of brief substitutions with recent-production 12AX7s I had on hand.  The differences were indeed clear, but neither substitute rivaled the impeccable tonal balance and transparency of the original.

Review Conditions
In the course of several months of listening, these amplifiers were matched with an impressive array of equipment, both upstream and downstream.  Preamplifiers were the WAVAC PR-T1 (sheer sonic bliss, for a net tab of almost $50,000), Atma-Sphere MP-3, ModWright SWL 9.0SE, and my reference VTL 7.5 line and Thor TA-3000 phono stages. The amps performed impeccably with all of them.

Loudspeakers included the Oskar Heil Kithara, ELAC 608.24, and my current reference Meadowlark Blue Heron 2.  (Note that there are no super-sensitive 100+dB speakers on this list.)  All three are fairly efficient designs with around 90dB sensitivity. I more typically drove all three with big, very powerful amplifiers, especially my VTL MB-750 Reference monoblocks.  But I was gratified to find that these little 55 Watt SETs are able to push those designs to surprisingly robust, room-filling listening levels without notable strain — something no 300B-based SET could do.  It was of course possible to push the amps into clipping in my more insane moods, but these amplifiers were quite comfortable producing volumes that would satisfy me 80% to 90% of the time.  These are SET amplifiers for those who, like me, are generally not big fans of horn-loaded loudspeakers.

The Sound Of The MD-805m
To cut to the chase (and, I suppose, give away the punch line), the sound of these amplifiers is virtually flawless. From the left-brain, audio-checklist viewpoint, the only reservations I have are in ultimate power output and ultimate bass performance. As I suggested earlier, their ability to drive reasonably efficient loudspeakers is hardly deficient unless judged against much higher-powered designs. I don't recall any other 50-Watt amps that do better with the kinds of speakers I used.

Bass response does not reach the subterranean depth and jump-out-of-your-seat impact and amplitude of some, especially solid-state, amplifiers. However, the bass is quick, tuneful and wholly continuous with the rendering of the higher frequencies. It is superior to what I have heard from any other SET amps.

Beyond those minor points — which are not deficiencies so much as expectable characteristics from this class of amplifier — I can offer nothing but superlatives. No matter what combination of equipment surrounded the amplifiers, they consistently delivered broad and commendably deep soundstaging, with stable and dimensional rendering of individual and ensemble instruments and voices. Altogether, their spatial resolution is absolutely first-rate.

I do not recall hearing any amplifier, regardless of type, power or cost, that is more consistently free of tonal colorations. The clarity and openness that flow from these remarkable 805 amplifiers is truly uncanny. They are a Crystal Palace for your music!

As my time with the amplifiers progressed, I noticed an interesting phenomenon. More and more frequently, I found myself listening at lower volume than is typically my practice. And no, that was not because of power limitations.  The sonic presentation was so comprehensively pleasing — harmonically complete, open and relaxing — that I simply didn't feel the need to turn it up! Probably no term in audio is as ubiquitous and indiscriminately used as "transparency." But these amplifiers would be a great choice as the poster child for the concept. From the subtle vocal modulations of jazz singer Tierney Sutton to the symphonic complexities of Stravinsky and Mahler, the MD-805m's simply "get it right" — in scale, in tonality, and most importantly in the ability to reach out and draw you emotionally into the music.

Conclusion
As always with WAVAC, the question of price/performance value is necessarily part of the equation. Yes $19,000 is a lot of money for any amplifier, and certainly for 55 Watts. But tempting as it may be to break out the old "If you have to ask, you can't afford it" clich้, in my opinion it really doesn't apply here. The purity and beauty these amps deliver make them worth strong consideration from any highly discerning listener who values musical truth over audio dazzle. If your loudspeakers and other equipment match up well, and of course if your budget permits, you owe it to yourself to listen to these very special amplifiers.

Specifications
Type: Monoblock tube amplifier
Power Tube: Single 805 directly heated triode
Power Output: 55 Watts
Frequency Response: 20Hz to 50kHz (-3dB)
Input Sensitivity: 1 Volt
Input Impedance: 10kOhms
S/N Ratio: >83dB
Load Impedance: 4 & 8 (16 optional) Ohms
Dimensions: 260 x 460 x 270 (WxDxH in mm)
Weight: 19kg (each)
Price: $19,000 per pair
Warranty: one year parts/labor; six months on tubes

Company Information
WAVAC Audio Lab - Sigma Co. Ltd.
1404-26 Nakada-Machi Yonezawa-Shi
Yamagata, Japan

Website: www.WAVAC-audio.jp