Power Amplifiers

Jones Audio PA-M300 Series 2 Monoblock Power Amplifier


In Use

The first thing that jumped out at me was the sound of the bass. Boom! Wham! Slam! Big, powerful, tight, focused, and viscerally thrilling bass. Not since I reviewed the Parasound JC-1 Halo monoblock amplifiers in August, 2004 have a heard such jaw-dropping bass from my system. The timpani thwacks at the start of Ivan Fischer's recordings of Mahler's Symphony No. 2, "Resurrection" (Channel Classics) were floor-shaking.

But that head-turning bass was only from the CD layer of a hybrid SACD, whose ultimate dynamic range is limited. A far bigger surprise was in store when Ray Burnham of Auraliti brought over the prototype L-1000 music player to prepare for the BAAS demonstration, and put on a not-yet-available hi-resolution file of Reference Recordings' fabled version of Copland's Symphony No. 3. This is the symphony from which the ubiquitous Fanfare for the Common Man originates. I wonder, when the Republican Party chose it as their election year theme song a campaign or two back, if any of the decision makers were aware that the composer was a liberal who narrowly escaped total vilification and career destruction by Sen. Joe McCarthy's House Un-American Activities Committee.

Well, if Joe had ever gotten the chance to hear what the Jones Audio amps could do with the big bass drum thwacks on this ultra-dynamic, hi-resolution file of Copland's symphony, he might have stopped pointing the finger outward and run for cover. The bass was like nothing I'd ever heard before in my room, or just about any room I can think of.

When we first played the track, I was experimenting with midrange port loading, and had loosely stuffing the rear ports on my speakers' upper modules with white anklet socks. The first time we turned the volume way up to realistic symphonic levels – not ear-deafening levels, but definitely loud – and the bass drum pounded in 24-bit, 88.2 kHz sound, one of the socks shot straight out the rear port and hit the wall behind the speaker!

Even more dramatic, the huge current draw required to reproduce such realistic thwacks soon tripped the internal protection circuit on the amps. The sequence sounded something like this: Boom, Pop (as the first sock shot out one of the rear ports), Boom-Boom, Pop (as the other sock shot out), Boom-Boom-Boom, Click (as the amps shut off).

This was accompanied by a huge emotional swing on my part that went from "What?" to "Wow!" to "Are you kidding!" to "Oh no!" in the space of a few measures. Right after Ray quipped, "How's that for a case of sock it to me," our elation crashed.

As we retrieved the socks, both Ray and I saw that the amps looked dead to the world. Then we realized that the BAAS demo was but two days away. We had no idea if we had burned them out, if they contained esoteric value fuses that we would never be able to replace in time, or what.

An emergency call to Jason Jones, who bless his heart was available, produced reassurance that the amp's internal circuit breaker had tripped to avoid damage, and would reset once the babies cooled. We able to turn the amps back on in a few minutes.

As a result of this quasi-hilarious mishap, the amps' headroom has been bumped up a bit to avoid similar unnecessary simulated meltdowns in the future. Glad to serve.

Bass, of course, was only one aspect of the sound. The rest of the range was also as tight as could be. Midrange was strong, and highs were brightly illumined, extended, but never piercing. (This is not a dark sounding amp by any means). In addition, as mentioned above, the dynamic range was far greater than I was accustomed to, especially from CD. The huge chorus at the end of Mahler No. 2 was astounding, as hundreds of singers, two soloists, gongs, bells, timpani and everything else in the huge Mahler orchestra joined together in one huge, clearly articulated outpouring of resurrectional release.

One of the reasons I wish I had been able to spend more time with the PA-M300 Series 2 monoblocks is that I've since learned far more about optimal positioning of the Eficion F300 loudspeakers. They are now considerably closer together, with less toe-in. I've also established that, at least in my room, the more the toe-in, the more the tonal balance shifts from midrange-full and top just right to midrange lean and top over-pronounced. I can even white out the sound by not toeing in enough. There is a delicate balance where top to bottom sounds in correct proportion both tonally and in volume, but it takes time and patience to dial it in.

While the Jones Audio monoblocks were at my home, I experimented with the exact degree of speaker toe-in by using a protractor. Please join me in a chorus of "the best laid plans of mice and men…" As it turned out, the protractor I was using was inaccurate, and whose 90º middle setting was more like 88.8º. As a result, when I tried to toe-in both speakers 2.5º, one speaker was actually angled closer to 3.7º, and the other 1.3º. This produced an uneven tonal balance between the two speakers, and skewed the certainty of my evaluation..

Hence, when I say that, if pushed to characterize the sound of these monoblocks, I would describe them as having just a touch of the muted silver, gunpowder gray patina that I recall from the Parasound Halo JC 1 monoblocks, I would also say with certainty that I cannot trust that call. Had the amps remained through the time when I finally found a Taiwan-sourced protractor that gave accurate readings, and was able to position the speakers properly, I'd feel far more comfortable describing their tonal balance.

Let us instead say this . . .