Thursday, June 23, 2011

A visit with the Audio Research D-52B power amplifier


With the arrival of summer, a young man’s (*cough*) fancy turns to power amplifiers. Okay, maybe not. Lately I’ve been more interested in looking at wooded property to buy, walking on the beach and trying to remember what it actually feels like to be a young man. I’ve also been modernizing my 1948 Bungalow into something a little more tasteful. To my eyes, a good-looking stereo always helps and since my recently acquired Audio Research SP-7 needed a playmate, I decided to purchase a matching amplifier.

Trolling through Audiogon the past few months has been interesting because Audio Research gear certainly holds its value. You see, I wanted an amplifier for a future speaker upgrade - perhaps Magnepans – so I was holding out for something with a bit of power. After passing by several expensive amplifiers, I finally gave in and purchased an Audio Research D-52B for only $350.

The original D-52 was introduced in the heady days of 1978 – famous for disco, punk rock and Jimmy Carter. The D-52B revision came out in 1979 and originally sold for a then expensive $995, later increased to $1295 and then $1395. Rated at 50Ws per channel into 8-ohm and only 80Ws per channel into 4-ohms, the D-52B isn’t exactly a powerhouse. But under the lid, you can see a massive transformer flanked by a large number of power supply capacitors. This is one underrated amplifier that should be able to deliver a nice wallop of short-term peak power.

Early Audio Research solid-state gear was met with derision by the audiophile press at the time. That is hardly unexpected since ARC was one of the few carriers left of the mystic tube flame. The introduction of solid-state gear certainly made them few friends and based on the number of Audiogon ads, they have certainly sold less SS than tubes. When I bought my solid-state Audio Research SP-7, sound quality was actually second-tier in my decision. I just wanted something reliable with quality long-lasting controls. However to my surprise, the SP-7 not only worked well, it sounded great.

So how does the Audio Research D-52B sound? Let’s find out.

When I first received the D-52B from the FedEx, I was surprised by the weight. This amplifier weighs in at a nice 39 pounds but still has a relatively compact size. As usual with ARC gear, build quality is high. Removing the lid revealed the previously mentioned large power transformer and (in this case replaced) power-supply capacitors. There are also four output devices per channel, a quality circuit board, and the much-hated but mysterious Audio Research “Analog Modules.”

The first stop was my second system which is to be the eventual home of this amplifier. I removed the Mitsubishi DA-A10 and installed the Audio Research D-52B. Since neither of these amplifiers has a proper power-supply switch, I used the switchable powered AC jack from the Audio Research SP-7. The two ARC pieces with their silver-faces, black handles and high-quality lettering make for a handsome pair. Turning on the SP-7, I was greeted with a nice green LED glow from the D-52B.

The KEF Q-60s in my second system are remarkably forgiving . They aren't all that detailed and the treble has a nice roll-off which helps out the worst of recordings. But even through these limitations, I can tell that the D-52B has more treble detail and apparent speed than the Mitsubishi DA-A10. Dynamics through the 8" Uniq driver are very good as is the overall sound. Though not as "rich" and "full" as a vintage tube amplifier, the D-52B seems to be quite transparent and resolving. I won't mention soundstaging or depth since this second system setup is woefully inadequate for that type of listening because the speakers are too close to the wall and the source quality is too low. At this price level, I'm listening for frequency aberrations and general fidelity. Paired with Audio Research SP-7, this is a surprisingly good system for the money. I'm looking forward to replacing my KEFs with something even better, bringing the my second system even further along.

The second stop was my main stereo rig. The Magnepan 1.6QRs are notorious for their current-sucking demands, so I was interested in seeing how this little amplifier would fare. The last amplifier I tested here, the B&K ST-140 rated at 105WPC, was capable enough but was a notch below the Threshold in sound quality. As usual, removing the mighty Threshold S/500 from the rack was a chore. In comparison the D-52B looks like a pipsqueak but sometimes good things come in small packages.

This turned out to be an unfair comparison against the Threshold S/500 which has five times the amount of available power. At higher listening levels, I could tell the D-52B was running out of steam. Mind you, it never clipped harshly, but dynamics became squashed and the soundstage flattened. However, at moderate listening levels or with less dynamic material, the ARC amplifier turned out to be quite pleasant. Though detail and depth seemed less than the Threshold amplifier, the overall sound was still quite musical. An example of this is my original pressing of Neil Young - Tonight's the Night. Through the Threshold amplifier, I can really get a great sense of the room and it almost feels like you are there. With the Audio Research D-52B the lower resolution leads to less space and depth, minimizing the illusion. However, along the width of the soundstage, every instrument kept its proper place. Voices were very natural sounding as was the treble extension. From Blue Nile to Neil Young, the ARC was a competent amplifier that only suffered when asked for more power than it could deliver.

The Audio Research D-52B is by no means a perfect amplifier, but it is much better than I expected. Since this is a relatively ancient design, I'm also willing to cut it a little slack. With only 50Ws of power, it's really not up to the task of driving inefficient speakers unless you have a small room or prefer lower listening levels. It's also not a particularly resolving amplifier or one that captures the total possible depth from a recording. However, it certainly doesn't deserve the bad press it has received - at least from a sonic point of view - I will have to wait and see about the reliability. But nonetheless, for a second system or for one just built around musical enjoyment, the Audio Research D-52B is an excellent performer. Recommended but with caveats.


Second System:
Preamplifier: Audio Research SP-7
Amplifier: Mitsubishi DA-A10
Analog: Dual CS-5000 turntable - Audio-Technica AT95E cartridge

Digital: Pioneer DVD-V7400
Speakers: KEF Q60
Speaker cable: Canare 4S11 Quadlink
Interconnects: Cardas Crosslink

Main System:
Preamplifier: Threshold FET-10/HL

Phono Preamplifier: Audio Sector Phono Stage
Amplifier: Threshold S/500
analog: VPI HW19 MkIII with SDS - Rega RB300 with Incognito wiring - Denon DL-103R
Speakers: Magnepan 1.6/QR with Sound Anchor Stands
Speaker cable: Kimber 4PR/8PR Bi-wire with banana jacks
Interconnects: Cardas Cross and Cardas Quadlink 5C


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