November 2014


World Premiere!
Pass Laboratories XA30.8 Power Amplifier
This 30 Watt Class A amp conveys an involving musical intimacy.
Review By Ron Nagle

Yowzer, Yowzer, step right up ladies and gentlemen, and listen to the eighth wonder of the world! You should not miss this once in a lifetime opportunity with the all new, and revolutionary, XA30.8 amplifier from Pass Labs! Hey, wait just a minute my Audiopals!

Nelson Pass doesn’t need a pitchman, as his reputation is most certainly secure within the field of audio signal amplification. After all we are talking Nelson Pass here. For many years he designed some of the most advanced and innovative High End audio components out there. His design process, or more aptly his thought process is made abundantly clear. You will find it outlined in the introduction that is contained in the XA30.8 owner’s manual. Unlike most audio engineers, Nelson Pass remains uniquely vocal that listening tests remain valuable and that electrical measurements alone do not fully characterize the sound of an amplifier. In part he tells us: "There have been cases of some state of the art engineering (efforts) resulting in economic failure, apparently because people did not care for the sound. With regard to amplifiers at least, I think we already have the measurement data in hand. The problem is in our failure to interpret it with respect to human perception. My experience is that under the right conditions the customer can often hear the difference, and his observations are not to be ignored." Amen Nelson.

Evolutionary?
Well yes and no, there were predecessors early on like the X.5 and XA.5 series amplifiers. However, at this point in time the $6500 XA30.8 has moved beyond these. The immediate predecessor was the XA30.5. While it is true that the XA30.8 shares some of the same specifications as the former XA30.5, you could not turn the former into the latter. True, they share the same power rating, 30 watts per channel with equal distortion specs over the same frequency spectrum. However, there is a major difference between the XA30.5 and the XA30.8, it is really like an entirely a new amplifier. Internally the front end uses a mixture of four each complementary JFET, MOSFET, and Toshiba bipolar devices. The Point 8 series was introduced in Las Vegas at the 2014 CES. The entire Point 8 series has a larger output stage and there are more output devices, plus an added current source and greater bias current. In addition the power supply is an all new design with added capacitance. As a consequence the amplifier has been beefed up. The XA30.8 weighs in at 85 lbs., and this represents an increase of 23 lbs. over the XA30.5. The chassis now has larger heat sinks due to the higher bias and current sources. Note: Over the entire Pass lineup the prefix XA designates Class A operation (low rail voltage and high bias current). While the X prefix amplifiers are high bias Class A/B i.e.: high rail voltage and lower bias current. Therefore the new XA30.8 uses higher bias current for lower distortion while the amplifier is in Class A operation. I’m certain that the Pass people would likely think of these changes as revisions, since nothing that preceded them was actually bad.

Physicality Speaking
At its debut in 2014 the XA30.8 faceplate was changed (I am told) to distinguish the series and update the appearance. For many years Pass Laboratory amplifiers looked like the present X.5 series of amplifiers, these have a two part face plate. The front section of this two part panel had a circular opening framing the large round bias meter. The bias meter dial was actually mounted on a second sub panel. Now only the X.5 line retains this two piece sculptured look. The original two layer aluminum fascia was a massive macho metal muy importanté front panel. I know all of that is only a design feature and that the appearance does not in any way premise sound quality, but I thought the two part face plate looked really cool.

The new X.8 series look is certainly O.K. but it has been trimmed down. The 0.75" inch front panel is essentially a single thick slab of aluminum with beveled edges. There are two slots near the bottom of the panel on either side of a centrally located mains power button. Happily the Pass people retained the large round Cyclops style bias meter centered on the front face. The meter has only one specific function. It shows the current draw of the amp and in the case of Class A amplifiers it stays pretty much at 12 o'clock. When you do exceed the Class A bias, the meter pointer may move to the right if you encounter big bass hits or large crescendos. If the pointer is left or right of center by 1/8" or so, it doesn't mean anything. It you are pegging it against its stop to the right then you are pulling 100 Watts plus out of the amp.

As an aside the meter looks really nice, you can see it glowing with a blue light in my darkened room. The XA30.8 has a 19" wide face and it is 21.25" from front to back and 7.375" high. The amplifiers heat sinks are huge, big enough for what might normally be found on an amplifier with ten times the power rating. The XA30.8 amplifier is 85 lbs. and it is easily the most massive 30 Watts per channel amplifier I have ever experienced.

The Business End
If you look around, at the back you will find both unbalanced RCA inputs and balanced XLR inputs. Note: The amplifier is shipped with U shaped wire jumpers in the XLR sockets. If you chose the RCA inputs than the XLR input sockets must have the U shaped jumpers connecting the input pin 3 to pin 1, ground. And of course the XLR wire jumpers are removed if you chose to use the balanced XLR inputs. Pass Labs provides four massive speaker cable binding posts, two per channel, a main AC power switch and just to the right of that a 5 Ampere fuse socket and below the fuse is an IEC style power cord receptacle. Additionally there are two mini binding posts intended for a 12 Volt trigger input, and last there is a grounding post labeled, "Signal Ground." This provides a chassis ground, not an earth ground.

Experientially Speaking
As it states in the Owner’s Manual, this amplifier draws a lot of power. The book says "give it lots of space". The XA30.8 Class A amplifier runs hot! Not so hot that it could harm anyone, but I would not advise leaving a plastic remote control on the top cover. About two hours after you turn it on you could probably keep a mug of coffee warm. Aviso: Each time you do turn on the XA30.8 it will take about 30 minutes for the sound to mature. Also when you depress the power on button the amplifier is on almost instantaneously, there is no turn on or turn off delay, no soft start. At one point when I turned on the amplifier the sound level was so loud I thought my speakers were fried. My bad, I forgot to turn down the Parasound preamplifiers volume control. Anecdotally, I used three pairs of speakers, My Aurum Cantus leisure 2ses are a two driver stand mounted pair with a ribbon tweeter. And my floor standing Rocket Strata Mini speakers have only average efficiency at 88dB/W/m. Added to both speaker systems is a Mark & Daniel Omni-Harmonizer. This is a separate tweeter with response out to 40 kHz. FYI, the Pass amplifier had absolutely no problems driving any of them.

When The Music Plays
I let the Pass amplifier play music many hours before ever attempting to listen critically. Additionally over a span of three weeks’ the XA30.8 seemed to improve a little more each time I sat down to listen. As always my path to the truth in a music composition is the sound of the human voice. Three full hours pass on the Pass before I cue up, Clap Hands Here Comes Charlie [Verve 835 646-2]. Seventeen classic songs flowing from the flawless voice of none other than the late, great Ella Fitzgerald. Of all the songs on this album the song that stays with me is, My Reverie. Like honey flowing from the cone her voice has an effortless liquidity that carries her into the room you sit in. In that room, just sit back and relax, I cannot find any faults. She sets a mood that leaves me wanting even more. So let’s listen to Ella Fitzgerald, Billy Holiday and Carmen McRae at the 1957 Newport Jazz Festival [Verve MGVS 6022]. Liner Notes: "On three successive nights recorded but never released three of the greatest jazz singers". The first ten tracks are all Ella now in a totally different venue. The stage pickups could be better but the audience sounds add to the live experience. Ella’s styling is now much more into Jazz phrasing. She rifts and turns and scats all the way through, Air Mail Special. And I find only Ella Fitzgerald can take sole possession of Lullaby of Birdland. Tracks eleven through sixteen are the voice of Billy Holiday. At track fifteen, Lady Sings the Blues. When listening, you can hear the sounds of a hard life imbued with a grainy sleepy sensuality. On Willow Weep for Me, we can touch the sadness in Billy. The last tracks, seventeen to twenty four are all Carman McRae. Her song Body and Soul is not subtle. Her pace and her vocal phrasing places the words right in your lap. And on track twenty she just seems to talk her way through the tune, Skyliner. A wonderful recording but much more than that it is an event through a time machine taking us back to 1957.

Let’s Rattle The Room
Can’t help myself, need to snoop out the amplifiers 30 WPC bottom end. At this point the midrange and treble have made their presence felt, so moving right along. Nothing beats this deep down bass demo. Fanfare for the Common Man [EijiOue and the Minnesota Orchestra]. Well darn, surprise surprise, it is all there and you can hear the impact plus bass rumble reverberating back from the walls. Now my Strata Mini speakers (No longer made) are about middle efficient @ 88dB/W/m, so that’s pretty good. Who would have thought a relatively small thirty watts per channel amplifier could paint the deepest bass overtones and the transient impact of a kettle drum. OK, I have heard some Solid State amplifiers with a bigger bass "Slam Factor" riding on the back of quicker transients. But, they did not, could not support the sound of this amplifiers realistic low distortion Class A midrange.

CODA
It takes a while to ferret out the heart of this amplifier. Not just because it takes time to warm up from a cold start. Much more than that you need to play a very wide variety of music to get to the truth. It is kind ‘a like a shadow you see far off on the periphery of your vision you turn to look and it melts away. This is certainly a pure conduit for music and purity is the hardest of all things to quantify, for it is to describe what is not there. The best way to characterize the XA30.8 is to relate the sound to a musical genre. I believe this 30 Watt Class A amplifier has the elusive ability to convey an involving musical intimacy. That conclusion lends itself to something like but not restricted to a string quartet. That also includes the intimacy necessary to fully understand the human voice. For me, this is my refuge where I can go to and escape the days trivial. To achieve this state-of-the-art the XA30.8 at $6500 is eminently reasonable. In the market place and at this date in time it should be considered middle priced. A pure conduit for music you ask? It truly is, and you must go and listen.

Semper Hi-Fi

Review Gear
Two Preamplifiers, my refurbished Audio Research SP-9 MK 3 and the Parasound Halo P5.
The Halo P5 allowed the use of balanced and unbalanced connections to the Pass Labs XA30.8. I can’t say that there was a marked difference in sound between those cables.

Three speaker systems, Reference Rocket Strata Mini 3.5-way speakers and stand mounted
Aurum Cantus 2SES speakers, 2-way & ribbon tweeters. Also Mark& Daniel Omni Harmonizers.

Digital sources, Marantz SACD/DVD DV8400 CD player with switchable input to a Music Hall DAC 25.3 up-sampling tube buffered Digital Converter. Also in system the Sangean HDT-1 Digital AM/FM Tuner.

Cables, Interconnect, Speaker cable, Kimber 12TC, Audioquest Red River XLR to Amplifier, RCA Nordost Red Dawn.

Mains Filter, Rickard Gray 20 Ampere Power station.

Ancillary: Note: Although not strictly a subject of this evaluation The Marantz CD 8400 and Music Hall 25.3 as well as the Parasound P5 preamplifier all have built in Digital to Analog Converters. This allowed me to listen to 16-bit/44.1kHz Red Book CD at times up-sampled to 24-bit/192kHz and SACD including new DSD disks. The Pass XA30.8 proved to be an extremely clear conduit of every system change.

Specifications
Type: Solid-state stereo amplifier
Frequency Response 1.5 Hz to 100 kHz
Operating Class: Class A 
Type Stereo
Gain: 26 dB 
Power Output: 30 Watts per channel @ 8 Ohm (60 @ 4 Ohm)
Distortion: 1% @ 1 kHz, full power
Maximum Output: 40 Volts
Maximum Output: 20 Amps
Input Impedance: 50 Ohm unbalanced RCA, 100 Ohm balanced XLR 
Damping Factor: 150
Slew Rate: 50 V/uS
Output Noise: 200 uV
Input CMRR: -60 dB
DC Offset: 0.05 Volts
Dimension: 19" x 21.25" x 7.5" (WxDxH)
Weight: 85 lbs.
Price: $6500

Company Information
Pass Laboratories Inc.
13395 New Airport Road
Suite G
Auburn, CA 9560

Voice: (530) 878-5350
Fax: (530) 878-5358
Website: www.PassLabs.com