GFA-7807 Power Amplifier
GDV-850 DVD Player
GTP-880 Surround Processor
GFA-7807 Power Amplifier
Let's start with the best news first. The clear star of this trio is the power amplifier. This Adcom GFA-7807 power amplifier offers you excellent sound, within its genre, and spectacular sonic value. Its sound is very similar to the Plinius Odeon, which has been highly praised by many reviewers (including me). As to its spectacular value, just consider the following facts: the Adcom GFA-7807 gives you the sound of the $11,000 Plinius Odeon, plus the bonus of 50% more power per channel (300 watts instead of 200 watts), plus the bonus of an extra channel (seven instead of six) at full power, plus the bonus of a 71% discount! This is not a typo. The Adcom 7 channel, 300 watt-per-channel GFA-7807 sells for merely $3200, which amounts to a 71% discount from the Odeon's $11,000. This also means the Adcom GFA-7807 is an outstanding value in terms of watts per dollar, giving you a total of 2100 watts into 8 ohms (3150 watts into 4 ohms!) for just $3200.
Further proof of this amplifier's spectacular value can be found in another interesting spec: pounds per dollar. The Adcom GFA-7807 weighs 119 pounds, which might well make it the champion in pounds per dollar among all power amplifiers, as well as one of the heaviest power amplifiers on one chassis, period. The sheer weight of a power amplifier can be a useful indicator of just how serious its design is in reaching for truly high end performance. The heaviest parts in a power amplifier tend to be the transformers and the heat sinks. Heavy transformers can indicate high power and high current capability, low source impedance, good coupling, and wide bandwidth, all of which can be important to achieving true high end sonic performance. Likewise, the weight of the heat sinks can be indicative of a power amplifier's sustainable power and current capability, and of its high bias, which tends to produce superior sonics. This Adcom GFA-7807 is one serious high end power amplifier, which you might not suspect from its bargain price.
And further evidence of the serious high end qualifications of this Adcom GFA-7807 can be found in its circuit and package design. No corners are cut for the sake of price point. The circuitry is entirely discrete, with no op amps or IC chips. The topology is said to be fully balanced, which doubles the number of parts required for most of the early stages, compared to the single ended topology employed by some other power amplifiers. The output stage runs in regular class AB, so there are no gimmicks trying to cut corners on heat dissipation requirements. The heat sinks and fins are contained within the amplifier package, rather than being at its outside periphery, which makes this amplifier package more attractive and friendlier to handle (at least so far as a hunk weighing 119 pounds can be deemed friendly to handle). Since this seven channel package can put out a total of 3150 watts RMS into 4 ohms, the question naturally arose of how Adcom can manage to handle the heat from such output, given that the heat fins are internal and that the output stage runs in full class AB. Adcom replied that the design of the heat dissipation package was optimized using sophisticated finite element analysis, and that a fan comes on when heat sink temperature reaches a predetermined point. In our listening tests, we never heard the fan come on, so the GFA-7807 ran dead quiet, and the amplifier package never even got abnormally warm, so that sophisticated finite element analysis design of the heat dissipation system must be really paying off.
The Adcom GFA-7807 has two power transformers instead of the usual one, with one power transformer dedicated to just the two main front channels, for best sonics where it counts the most. There are seven distinct secondary windings on the two power transformers, so each channel has its own dedicated secondary, and then also, very importantly, each channel has its own capacitor filter bank reservoir. This makes the Adcom GFA-7807 very close to being an amplifier with seven independent mono channels that happen to share one chassis but otherwise are almost entirely isolated from one another. This perfectionist design tactic of independent power supplies can have important sonic benefits, since each independent channel does not suffer crosstalk or modulation distortion, from signal activity in the other channels modulating its power supply. It's costly to build in seven power supplies instead of one (with seven capacitor filter banks, seven rectifiers, etc.), and one might expect to see this perfectionist tactic in a very expensive power amplifier, but it is a welcome surprise to see this in a power amplifier at such a bargain price.
Of course, all these perfectionist tactics and serious high end design intentions only count if the end result delivers the goods in sonic performance. The Adcom GFA-7807 is a triumph in this regard, when set up optimally. The review of the Plinius Odeon (WSR September 2003) discussed in depth the nature of the tube-like sound of that solid state amplifier, and the euphonic benefits of that sound, for both music and film soundtracks. If you have at hand that extensive review to re-read, it suffices to say here that the sound of the $3200 Adcom GFA-7807 is virtually identical to the $11,000 Plinius Odeon, and that the Adcom GFA-7807 gives you the further bonus of 50% more power and also that full power for a seventh channel (the Plinius Odeon had only six channels at full power, or alternatively five channels at full power plus two channels at half power).
If you don't have at hand our review of the Plinius Odeon, here is a brief recap of the sound of the Plinius Odeon and now also the Adcom GFA-7807. The Adcom GFA-7807 (and Plinius Odeon) execute a transformation of the audio signal that is in our professional judgment very euphonically beneficial, transforming the sound of typically too-closely-miked recordings into an accurate semblance of the sound you would actually hear live from a normal listening distance. This euphonic transformation also accurately mimics classic tube sound, giving you the euphonic benefits of tube sound but with the practicality of a high powered solid state amplifier.
Specifically, the bass regions are rich, full, and powerful, richer than typical solid state bass, yet still having very good woofer control. The warmth region is likewise very rich and full, giving full size and powerful hefty presence to the cavities and sounding boards of musical instruments and human voices. The upper midrange is polite or recessed, which puts the music (and all sounds) at a reasonable, naturally lifelike distance, instead of being artificially in your face or inside the loudspeaker box, as typically close miked recordings tend to do.
The trebles are beautifully delicate, sweet, and softly defocused. They are also wonderfully airy, open, and extended. This accurately mimics what happens to the trebles of live music, as they pass through a long distance of air on their way to your distant live concert seat, and as they ricochet and reverberate around a concert hall. If you were to hear live music from the very close perspective that the typical close up microphone hears, its trebles would sound much harder, and more articulate, with more coherent phase to all transient attacks. But the sound of live music's trebles that you hear from your typically much more distant seat is much sweeter and softer, with mixed phase and consequent defocus of all transient attacks, because you are sitting in the much more distant reverberant field. So that is the sound that you are accustomed to as your reference for live music. By executing its precise euphonic transformation of the audio signal, the Adcom GFA-7807 (like the Plinius Odeon) transforms the sound picked up by the typically too close recording microphones into a more accurate facsimile of the sound you know as the sound of live music.
The Adcom GFA-7807's transformation of the trebles works hand in hand with its polite, recessed upper midrange, and its rich warmth and bass, to create from typically too closely miked recordings a sound that is more accurate to the sound you know and expect from live music. The total sonic transformation makes recordings, both music and film soundtracks, simply sound more natural. It also creates a very relaxing, enjoyable listening experience. And it accurately mimics, from a solid state circuit, the sound of classic tube amplifiers. It is also very effective at making substandard recordings more musically listenable. For example, most film soundtracks and many music recordings (e.g. rock) are not only too closely miked, but also include excessive artificial hardness from excessive processing through IC chips, etc. The Adcom GFA-7807's transformation makes these recordings much more listenable and musically enjoyable.
Note however that this sonic transformation is indeed a transformation, and as such is not literally accurate to the audio signal being input to the amplifier. There are other amplifiers that are more literally accurate to the input signal, and if you want this, there are a variety of other excellent amplifiers, both tube and solid state, to choose from. The very best audio amplifiers you can buy are more accurate to the input signal, and are more transparent and articulate, yet still sound musically natural on most decent recordings. To date, these ultimate amplifiers are available only in stereo or monoblock configurations, so if you truly want the ultimate in surround sound you will have to pay for multiple amplifier chassis to obtain the multiple channels needed for surround sound. These ultimate amplifiers include tube amplifiers such as the Audio Research VTM-200 and new VTL Siegfried, and solid state amplifiers such as the Clayton and McCormack DNA-500. Multichannel amplifiers occupy a second sonic tier, somewhat below the ultimate sonic performance of the very best stereo and monoblock amplifiers, and here too you have a wide choice of sonic personalities. You can opt for the crystal clear solid state crispness of amplifiers such as the excellent Arcam P7, or you can choose an example of what we would call the ideal midpoint between solid state and tube sound, such as the McCormack DNA-HT5. But if you want the sonic benefits of a euphonically natural transformation and tube sound from your multichannel amplifier, then the Adcom GFA-7807 is a great choice, especially at its irresistible bargain price.
How did Adcom manage to deliver such an outstanding amplifier, with such beautiful sound and such perfectionist construction integrity, at such a bargain price? The GFA-7807 owes its existence and credentials to the confluence of two major forces. Adcom itself has a long tradition of offering good to very good sounding products at bargain prices, so it knows how to build products efficiently (the current range of Adcom products are built in Thailand). The other major force is a person, Dan Donnelly. Dan used to work at California Audio Labs, and was responsible for their monster, no-compromise amplifiers. CAL had a heritage of tube products and tube sound, so Dan is also an expert at getting musical tube sound from solid state circuits. Dan brought these talents to Adcom, thus enabling Adcom to bring you the beauty of tube sound, executed in a massive, no-compromise engineering and construction triumph like this GFA-7807 power amplifier. Adcom, to their credit, heeded Dan's perfectionist instincts, and did not skimp or cut corners in specifying the build of this monster amplifier. And Adcom, with their in-house expertise at building efficiently for less cost, has managed to deliver this engineering and construction perfectionism to you at a spectacularly low price.
To help you choose the kind of sound you want, we directly compared the Adcom GFA-7807 to the McCormack DNA-HT5, so we could precisely describe the sonic pros and cons for you. To properly evaluate these two power amplifiers, we substituted each in turn into a known, constant reference system. For the evaluation of each of the three Adcom products in this review to be scientifically valid, it was important to first substitute them into the reference system singly, one at a time, thereby properly controlling the variables in the listening tests by varying only one link at a time (and postponing until later the distinct assessment of how these Adcom units sound together as a team, in various combinations).
It was also scientifically important to employ a reference system that is very revealing and neutral, even if it included expensive components that might not typically be used with value oriented products like these Adcom units. That's because we (and you) want to learn exactly what these Adcom units sound like and are capable of doing, in precise and absolute terms (later, after we have gauged their absolute performance, we can assess the distinct question of sonic value for the money). Thus, it's important that the rest of the reference system be truly excellent. Only in this way can we (and you) be sure that the sonic strengths of each Adcom unit were evaluated at their sonic best and at their full potential. Only in this way can we (and you) be sure that colorations or sonic weaknesses heard are truly intrinsic to each unit under review, and are not due to some other link in the chain. And, only in this way can we (and you) be sure that sonic weaknesses of a unit under review are fully exposed, rather than being masked, offset, or obscured by some other imperfect links in the chain. Therefore, in our reference system to test these Adcom units we employed very transparent, revealing, and neutral reference quality component links, such as the Arcam DV-27A as a source, Nordost Valhalla loudspeaker cables, Verity loudspeakers, Nordost Optix video cables, and a Princeton HD CRT video monitor.
How did the sound of the Adcom GFA-7807 compare to the McCormack DNA-HT-5? It was easy to hear that the McCormack is, objectively speaking, the more accurate amplifier, and slightly more transparently revealing of true musical (and soundtrack) information. The McCormack has tighter bass with better definition. Its tonal balance is much more accurate to the input signal, especially in the upper midrange, where it is not recessed like the Adcom, so musical instruments and film sound effects have better tactile presence and more realistic dynamic bite and impact. In the trebles the McCormack is more articulate and informative, with better individualization, coherence, focus, and slightly better transparency. Bear in mind that the McCormack itself is already slightly relaxed in sound, being at that midpoint between tube and solid state sound, so even with its superior articulation it is still enjoyably sweet and natural sounding (as opposed to many other solid state amplifiers which, with their typical solid state sound, seem artificially crisp or hard in their articulation).
The Adcom GFA-7807 is, like the Plinius Odeon, even more sonically relaxed than the McCormack DNA-HT5. Even though the Adcom is objectively not as literally accurate or informative as the McCormack, it is subjectively even more relaxing and is very enjoyable, especially with most film soundtracks and many suboptimal music recordings. The Adcom's euphonic transformation is, like that of the 344% more expensive Plinius Odeon, nearly perfect at accurately mimicking, from most recordings, what they would actually sound like when heard live at the usual audience listening distance in a normal venue. In other words, both the nature and the degree of the Adcom's euphonic transformation are, to quote Goldilocks, just right.
Yes, the GFA-7807 has a sonic personality, and is, objectively speaking, not neutral or accurate to its input signal. But its sonic personality is so effective at re-creating a different kind of accuracy, accuracy to your live listening experience, that we don't award any demerits for this particular sonic personality. Of course, it's my job as a reviewer to tell you about this sonic personality, so you can make an informed decision as to whether you want this in your power amplifier, or whether you want instead a power amplifier that is more literally accurate to its input signal. If you do want this euphonic listening experience from your system that reminds you of the live sound you heard at concerts, then the power amplifier is a good place to accomplish the euphonic transformation that gives you this listening experience. You can obtain this euphonic transformation in a power amplifier by employing a tube amplifier with classic tube sound, or you can employ a solid state power amplifier that wonderfully mimics this classic tube sound, such as the Plinius Odeon or this Adcom GFA-7807 at 29% of the Odeon's price.
The Adcom GFA-7807's sonic personality also imposes a transformation upon the stereo imaging and surround imaging, and here too it is very euphonic and tasteful. Its upper midrange tonal politeness or recession puts music and sonic events at a greater distance from you the listener, and helps to enlarge and deepen the perceived sonic stage up front and the perceived sonic space all around you. And its soft, sweet defocus in the trebles consistently extends this sonic portrait, by giving you the kind of treble sound you would hear live if the music and sonic events really were happening at that greater distance. Thus, the Adcom's imaging transformation is very effective at offsetting the typical shallow, up front, in-your-face imaging that many recordings and most soundtracks have due to their too close miking.
Many other amplifiers that are literally accurate, especially solid state ones, restrict the imaging to a shallow plane in the line between the loudspeaker locations in your room, which tends to claustrophobically hem you in and make you realize that you are still trapped in your small room and have not been aurally transported to the much larger venue of the original recording. Sometimes that other amplifier is partly to blame for this, but the close miking employed for most recordings is often also at fault (that's why we make a point of using recordings with spaciously miked imaging to evaluate intrinsic imaging capabilities of products under review). The Adcom GFA-7807 is wonderfully effective at offsetting this shallow claustrophobia from typically close miked recordings and soundtracks, and giving you a large, deep surround space.
The McCormack HT5, with its more tonally accurate upper midrange and more articulate trebles, does not place music and sonic events at as great a distance as the Adcom does, and so does not create quite as large and deep a surround space. But, to its credit, the McCormack does reveal better layering within the depth of the musical ensemble or sonic events, portraying some as being closer to you (more up front) and others as being farther away, while the Adcom portrays them all as being more uniformly far away. And, with its sonic personality being at that ideal midpoint between tube and solid state, the McCormack still bestows some measure of sweetness and relaxed, airy ease upon the hardness of typically too closely miked recordings and soundtracks. The McCormack also slightly betters the Adcom in revealing the ambience and reverberant character of the hall. This is probably because the upper midrange contains a lot of information about hall ambience and
(Continued on page 124)