Adcom GFA-7700 5-Channel Power Amplifier
Power amplifier with 175 WPC x 5 channel into 8 ohms (all channels driven), Rated power bandwidth 1.5Hz to 100KHz (-3db), 120,000 uF of power supply filter capacitance, DB-25 connection for signal input, thermal overload and distortion LEDs for all channels, non-inverting, 5-way binding posts, 12V trigger via miniplug, independently fused discrete power amplifier modules fed by custom-made large torroidal transformer, 7.25 H x 17 W x 15 D, 56 pounds, 2-year warranty.
Krell Showcase Surround Processor, Definitive Technology BP2002tl main speakers, C/L/R2002 center speaker, BP2 rear speakers, Rotel RLC1050 line conditioner, Marantz DV8300 DVD player, Audioquest Cables, Krell Showcase 5 Amplifier ($4500) and Aragon 2005 ($2500) for comparison.
There wasnt much to do setup-wise with this amplifier. I connected the amplifier to the Krell processors unbalanced outputs and both analog and digital cables fed the processor from the Marantz DVD player. I planned to use the matching Krell Showcase amplifier as a comparison piece, but abandoned that idea after the first listening test. Instead, I primarily used the Aragon 2005 for comparison listening. Keep in mind that the Aragon amplifier sells for $1000 more. Unfortunately, I didnt have another 5-channel amplifier in the same price class on hand. I left the amplifier powered for four days before doing any critical listening. It ran warm, but was not hot, even after playing for a period of hours.
I opened the manual and was pleasantly surprised to find it detailed, well written, and very informative. It covers placement of the amplifier, ways to eliminate hum if it should exist, and has sections on every control, connection, and feature of the amplifier.
ListeningInitial Comparison with Krell Amplifier
At first I planned to pit the Krell Showcase 5 amplifier against the Adcom, but soon realized that this was an unfair comparison. I began the listening test with Chapter 11 from Gladiator. The voice came across as congested and much more metallic sounding on the Adcom amplifier. The sound could be characterized as unclean, rough, indelicate, constricted, gritty, and lacking in dimensionality. After this audition, I decided that an amplifier closer in price to the Adcom would be a much more sensible comparison. After all, you do get what you pay for most of the time.
Listening IVersus Aragon 2005 Amplifier
I began this comparison with track 2, La Vie En Rose, from a multi-channel SACD collaboration between Tony Bennett and k.d. Lang called A Wonderful World. The Aragon added more depth to the presentation and emphasized the high frequencies compared to the GFA-7700. I noticed a difference in the bass, which seemed deeper and more solidstrange because Adcoms reputation has always been of strong solid bass: Bass all over the place as Stereophiles Sam Tellig was so fond of saying. When I switched back and forth, I discerned a difference in the voice as well. There was a slight warmth and chalkiness that the Adcom imparted to the voice that the Aragon did not. In the middle of the piece when a guitar comes in, the Adcom draws your attention immediately to the solo performance and the orchestration takes a back seat. While listening to the Aragon, my attention was drawn to the sounds in back, and the guitar was less forward and present in the mix.
I switched gears and put on Chapter 3 from Mission Impossible 2. The Aragon seemed to have better transient response, while the Adcom was less congested. The Aragon sound showed off more of the spatial properties on the disc and gave the impression of higher resolution. This scene starts with dancers tap dancing (Spanish style?) on a hard wood surface. There was greater clarity and more impact on each tap with the Aragon. By comparison, the Adcom response seemed rolled off. The Aragon was more natural from top to bottom. There was greater low level extraction and slightly better definition on voice with the Aragon. The Adcom made the sound richer, warmer, and even softer on the top end, but seemed to do so at the expense of heightened resolution. I can see how with a different combination of equipment, speaker system, or taste the Adcom might win out. But with this combination, I still prefer the Aragon. You might ask if the difference was worth the price, and the my answer would be, Yes. But you arent reading a review of a $1500 piece if you could afford a $2500 one are you?
I decided to do a little 2-channel listening to see if the difference would be as dramatic as with the multi-channel recordings. I put on track 2, Night Moves, from a DCC Compact Classics version of Bob Seger & The Silver Bullet Bands Night Moves. On this track Bobs voice sounded a little wispier on the Adcom. Also, there was richness added to the guitar strings and more punch in the bass. The Aragon had better definition, but on lesser recordings this might lead to fatigue. However, the Aragon added a little more sheen to the string strumming, had more resolve on the voice when it trailed off, and generally seemed to offer better transient response. The voice on this recording isnt the greatest and it was interesting to see what the two amplifiers would do with it. At times, I felt I preferred the Adcom, and it was probably due to a little extra warmth.
Next was track 4, Speak Low (alternate take), off Hank Mobleys Peckin Time record. The 2005 sounded lighter and quicker. When I heard the horn sound through the Adcom I thought there was distortion on the recording, but through the Aragon I realized it was the sound of the artists breathing changing as he blew into the saxophone. There was more depth and a noticeable increase in high frequency content on cymbals with the Aragon. Drums were freer with better transient response, and the recording was rendered with greater delicacy. The Adcom seemed a little toned downnot congested, but slightly veiled. Some may prefer the extra bit of warmth the GFA-7700 imparted to the recording. Again, my bias towards resolution and detail leads me to prefer the Aragon in the test system. Personal preference or different equipment may have yielded a preference for the Adcom.
I went back to movies and put on the excerpt from Moulin Rouge off the DTS Sampler #6. Female voice was sweet and the music sounded rich and full. As the scene continues, the music builds to a powerful conclusion. The Adcom seemed to have no trouble with this passage at reasonable levels. I was able to make the amplifier distort, but not at a volume that any sane person would use to listen. The GFA-7700 generally delivered a big, bold sound and seemed to have fairly good control of the loudspeaker. In comparison to megabuck amplifiers, it seems to lack the last bit of control and is not as effortless in presentation as these amplifiers are.
On track 10, Where Is The Love, by Jesse & Trina on the Dead Presidents Soundtrack, I noted good bass and a clean high end. The male and female singing parts complemented each other well. This recording has a little sibilance, but the Adcom didnt make it worse than it should have been. The sound was like dark chocolaterich and slightly thick. Definition and resolution was good, but not amazing. The amplifier is extremely quiet. I felt the extreme top end and air were missing only if I compared the GFA-7700 to a more expensive amplifier. The benefits yielded a larger, more defined acoustic space.
For a journey to the classical side of life, I tried track 10 from a Deutsche Grammophon Sampler (439 597-2): Beethovens Cello Sonata op. 102 no. 21st Movt: Allegro con brio. The music sounded very relaxed and easy to listen to. To use an oceanographic analogy, some equipment might give the impression of crashing waves in a tumultuous ocean. The Adcom resembles pleasant ripples in a tide poolno irritation or pounding dynamics. For some listeners the attack would be insufficient and lacking bite, but for background listening it was entirely unobjectionable. The cello was rich with character and piano sounded as if it were whispering to the cello in a hurried, excited fashion. Nothing was calling attention to itself.
Track 2, Hella Good, from No Doubts Rock Steady proved to me this amplifier could really rock! Bass was tight and was not lacking in weight. I just wanted to turn the music up and bop my head to the music. This album sounds a little bit produced/processed but is better than most of the records I hear these days. The percussive sounds panned back and forth filling the room with sound that was wide and very much in your face just like it is supposed to be.
Lastly, I listened to chapters 16 and 17 from Black Hawk Down. This movie is about as intense as they come and these scenes blend background sounds with various effects, dialogue, and music. All this sound is coming from every direction and the Adcom seems to handle it with no problem. Bullets kept whizzing by in every direction and at one point the empty DVD case that I set on top of the left loudspeaker moved after a gunshot went byeerie.
From the beginning of the testing, I put the Adcom GFA-7700 up against some pretty stiff competitionamps costing up to more than twice as much. It may sound like I was not very impressed with the Adcom GFA-7700, but this is not the case. The Adcom always acquitted itself quite well. Its always possible to get more if you are willing to spend more, but what do you get for $1500? You get a beefy, well-built, powerful 5-channel amplifier. Its sound leaned toward richness, warmth, and power. If this is what you are looking for in a surround amplifier, and the Adcom GFA-7700 is in your price range then give it an auditionit just might make you say ahhhh.
- Brian Bloom