Sunfire Theater Grand 7400 Multi-channel Amplifier 
Home Theater Power Amplifiers Multi-Channel Amplifiers
Written by Ken Taraszka, MD   
Thursday, 01 February 2007


Grown men have spent their entire lives fighting and even dying for it. We often associate power with size and weight, but can be fooled by the little guy whose abilities can drop the largest of men. Bob Carver is known for packing amazing amounts of power into the smallest and lightest of boxes with his amplifiers, and it seems Mr. Carver has empowered yet another “little guy” with his new Theater Grand Amplifier 7400. As president of Sunfire, Bob Carver has been a major player in the audio industry since 1970, when he founded Phase Linear, and he has kept pace with the rapidly changing business throughout the years. His advances in amplifier technology are legendary and his new top of the line seven-channel amplifier, the Sunfire Theater Grand Amplifier 7400, puts out a rated 400 watts per channel into eight ohms into all seven channels, and doubles down to 1600 watts per channel into two ohms for peaks. It offers two different output impedances for the front channels, both balanced and single-ended inputs with the ability to daisy chain multiple channels together for bi- and even tri-amping your speakers, and multiple options for powering up the amp. All this comes at a price of just $4,449.

When the new TGA 7400 arrived, I quickly unpacked it from its box and high-density foam and carefully unwrapped it to reveal the new look Sunfire has bestowed upon its components. Gone are the rounded edges of the previous models; they have been replaced with a milled aluminum faceplate and steel case. The side edges of the faceplate curve in slightly, giving the faceplate the look of being curved as well. The front of the amp is otherwise pretty sparse, exhibiting only a small power button in the upper left side with an LED above it. The rear is far more complex. On the right side are nine sets of binding posts for the front left and right speakers. This amp offers two types of outputs for these speakers, current source and voltage source, with one associated fuse for each of these channels current source options, and five sets of binding posts for the remaining channels. The IEC plug for the removable power cord is located in the bottom right. Seven sets of inputs are on the left, each offering two single-ended and one balanced input. On the far left side are the 12-volt triggers and an auto on/off switch that allows you to choose how to activate the amp, either keeping it on at all times or allowing it to be turned on either by the 12-volt triggers or whenever an audio signal is present on any of the channels. All the speaker binding posts are gold-plated and accept spades, bananas and bare wire. Threaded 12mm gold-plated nuts bind your choice of terminals to the posts. The amplifier measures just 17 inches wide, 5.9 inches tall and 16.7 inches deep and weighs only 40 pounds. Sunfire is able to pack so much punch into such a small and light amplifier in great part due to the use of their Tracking Downconverter™ technology, which provides high current power on an as-needed basis that greatly minimizes heat production, and therefore the need for heat sinks or a fan to maintain proper operating temperature.

I connected this amp to my Canton Vento speakers with Transparent Reference cables and to my reference home theater gear, the Meridian 861v4 preamp processor, Meridian G98 DH player, Teac Esoteric DV-50s and Toshiba HD-XA1 HD DVD player, for evaluation. Power was fed to the amp via its own dedicated 20-amp circuit, run through a Chang Lightspeed CLS 9900 Amp power conditioner. Due to some changes in my main system’s wiring, I had to relocate the amp to the front of the room, and I had not gotten around to having the electrician move one of my dedicated 20-amp lines to that part of the theater. When I first plugged in and powered up this amp on the line that also does the fans and lights for the room, the lights dimmed for nearly two seconds. I immediately switched over to one of my dedicated lines with a longer cord, as this amp was obviously going to need some good power to perform at its best and my room still has a few power demons haunting it.

Multi-channel amplifiers tend to get pretty crowded on the back plate, and this is no exception to that rule. Packing nine sets of binding posts and seven sets of inputs leaves little free space. The fact that the binding posts have 12-millimeter nuts to tightly compress the wire terminals was a big help here. These allowed me to secure the position of my wires so that they stayed put. While it took some finesse and a little planning, I was able to easily connect all my speaker wires to the amp. Had I used wires with very large terminations, this might not have been the case. Low-level inputs were connected via the balanced inputs initially. Then, in order to use four channels of this amp to bi-amp my front speakers with both current and voltage source, I used the RCA inputs.

The Sunfire TGA 7400 offers two different outputs for the front speakers, current source and voltage source. Current source is the output method most frequently associated with tube amplifiers, while voltage source is most often associated with solid-state amplification. The inclusion of these two different outputs allows you to tailor the sound for the main speakers several ways. You can obviously use either one or the other, or bi-amp or bi-wire them using both. You could even bi-amp then with four channels of voltage source output. I initially connected the front speakers to the voltage source outputs, and then switched to the current source. For bi-wiring, Sunfire recommends using the voltage source for the bass and current source for the highs. I tried this set-up, as well as bi-amping my Canton’s with four amplifier channels. After making all the necessary connections, I set the auto/on/off switch to “on,” enabling the signal sensing option for automatically turning on the amp, and let the entire set-up burn in for a little over 100 hours before doing any critical listening. The initial set-up took me several hours, as I had to rewire and relocate numerous components in my home theater. Had I just needed to switch out the amps, I could have been done in 15 or 20 minutes – it was quite simple.

Music and Movies
The Beastie Boys Paul’s Boutique (Capitol Records) is my absolute favorite album of theirs. It’s got a great flow, groove and deep bass too rarely seen in modern albums, and Rick Rubin’s exceptional recording skills make it a great disk to for listening. The Sunfire amp’s powerful ease of reproduction had me cranking this disc to obscene levels, where the TGA held tight, giving me all the power I could need. During “High Plains Drifter,” the bass was powerfully displayed, shaking the metal sculptures on my wall to the point that I have since removed them from that room. During “Car Thief,” the bass simply slammed me. Comparing the voltage source vs. current source outputs for the front two speakers, the current source outputs offered a less edgy top end to the sound, but I found the air and liveliness of the lower end to be better on the voltage source for this track. I switched between them several times with different songs and seemed to always feel the same. On “Johnny Royal,” the bass was fuller. Though it didn’t seem to go as deep with the voltage source compared to the current source, I found this is a plus, as it allows you to tailor the sound of the amp to your listening tastes, speakers and room. “Hey Ladies” had excellent air while maintaining the dynamics this song needs. The bells had an ease and naturalness to them I greatly appreciated. To take it to the next level, I bi-amped the front speakers with the front channel powering the highs via the current source and the second channel’s voltage source powering the lower end. Though this required two sets of (ideally) identical wire, this was the best of both worlds, offering the best sound I got from this amp, with smooth highs and powerful tight bass. This does require using the RCA connections to the amp to allow daisy-chaining the multiple channels, but the sonics offered by this set-up were worth the extra cabling to my ears.

I was so happy with the powerful presentation of this amplifier that I went to some old school funk to further test it. Parliament’s Mothership Connection (Mercury) is an amazingly fun album, and if you don’t own it, you owe it to yourself to buy it. Its deep grooves and powerful vocals are unmatched and the TGA 7400 was able to play this album at the levels it deserves. “Give Up The Funk (Tear The Roof Off The Sucker)” is not only one of the best funk songs of all time, but also a great test of gear as it displays the numerous vocals and deep bass grooves ever present in this album. The TGA did a great job powering the bass while keeping the voices clear. The synthesizer flew into and out of the soundstage and, once again, I found myself listening at higher than normal levels due to this amp’s ease of reproduction. “Handcuffs” showed this amplifier’s ability to handle complex passages and widely disparate range with ease. “P. Funk (Wants To Get Funked Up)” further demonstrated this amp’s ability to handle dynamics and deep bass while maintaining smooth clarity of vocals. Though I often found myself playing this album at very high listening levels, the amp never showed signs of distortion.

Nine Inch Nails’ The Downward Spiral (Interscope Records) is an old favorite industrial album of mine, and now it is available on SACD, so to further push this amp to its limits, I cued it up. NIN’s older material can be trying on an amplifier, as the music is extremely complex. Subtle backgrounds often connect entire songs, with huge swings in intensity interspersed with quiet, subtle and often musical interludes. The second song of the disk, “Piggy,” showed full bass and kept vocals clear while easily handling the wide dynamics of the piece. Even with all channels producing the extreme volumes this disc deserves, the Theater Grand Amplifier showed no signs of weakness. There was a little less detail in the more complicated passages than I’ve heard in higher-end amplifiers, but the extreme dynamics and thunderous bass afforded me by this amp were simply amazing, and the transitions from ear-splitting levels to quiet passages were impressive. As the rim shots of the drums came in, the attack was startling, while maintaining clarity not often found at this volume level. “Hurt” is my favorite song on this album, and the TGA kept me enthralled with its ease of reproduction at extreme listening levels while maintaining good separation and filling the room with a massive soundstage.

Action movies truly need dynamics for impact, so I cued up “Mission Impossible: III” (Paramount Home Entertainment) on HD DVD to further test this amp. It didn’t fail to impress me. The dynamics this amplifier is capable of producing are amazing, even with my power-hungry Canton Vento speakers. During the mission in Berlin, the amp easily reproduced the subtlety of small details, such as the dropping of the grenade and the ever-present background music, while handling the intense dynamics of guns and explosions throughout the scene. Voices were easily discerned and had a fullness and depth not often heard in theater systems. Much of this movie’s soundtrack contains deep musical bass, and the Theater Grand Amplifier 7400 had no trouble with it. The helicopter chase scene not only showed the power of this amp, but also its ability to transition between speakers. I found the dynamics from this amplifier impressive, to say the least. It likes to rock and does so well. The rumble when Owen Davian (Philip Seymour Hoffman) is held outside the flying jet shook my home, while the sounds of small items bouncing around the cabin of the plane remained clear and well-placed. The slightly forward sound and amazing dynamics of this amp made movies highly enjoyable to listen to and truly lifelike.

Tori Amos has been one of my longstanding musical loves, and her enthusiasm for my home state of Florida left her to finish the Scarlet’s Walk tour at the Sound Advice Amphitheater in West Palm, where she recorded her concert DVD Welcome to Sunny Florida. Tori has the ability to play softly and delicately and to rock out as well. Her keyboards and Bosendorfer piano can truly test the merits of any system, and I found excellent handling of the dynamics she is known for, while the bass stayed full and deep. With these challenging musical passages, the Sunfire TGA 7400 lacked some of the separation my reference amps exhibit, but made for an exciting and lively recreation of the concert. “Crucify” filled my room with Tori’s voice and its echoes gave a “being there” feel to the song. Her voice was sharp, with just the slightest sibilance to it. The drums that start out the song “Cornflake Girl” had a solid kick to them and, as Tori ramped up the song, the bass of her piano had a wonderful resonance. Transitions were fast and well handled, allowing near silence to quickly explode into musical intensity. The sound character stayed the same at low to moderate listening levels, as well as at extremely high volumes. “Bells for Her” showed the heft I am used to from Tori’s piano, and the stand-up bass resonated through my room while the shaker was placed to the left, just where it would seem to be from the stage set-up. The lone piano notes at the start of “Leather” seem to float in the air, while Tori’s voice starts filling the room with her eerie staccato. “Precious Things” is one of Tori’s more aggressive songs, and this DVD’s version is a great example of it. I cranked up the volume to the 98 decibel range and was glad to see the TGA had no problems maintaining its composure. The powerful bass of her Bosendorfer piano was well articulated, even at these listening levels, while her voice managed to send chills down my spine. The bass lacked some of the absolute authority I find in some higher-end amplifiers, but the TGA 7400’s infallible handling of dynamics more than made up for this to my ears. After several hours beating this amp up with loud, complicated multi-channel playback, it was only warm to the touch.

The Downside
Though it is tough to find fault with this amplifier, as it does so much well, it is my job to find areas where there is room for improvement. Bass, though clearly extended to the lowest of registers, lacked some of the authority of higher-end amps, and separation during complicated passages was less than with my much more expensive reference gear. This is not unexpected, as the amps I am using cost more for two channels of amplification than the Sunfire does for all seven. Given the price difference, the Sunfire did an amazing job.

The binding posts are pretty close together, again not unexpected on a seven-channel amplifier. I was able to easily connect all my wires, but had I used some others I keep around, this might not have been the case. The new look of the Sunfire gear appeals to me, but aesthetics are user-dependent and you will need to make your own judgment. I did all my listening to this amp on its own dedicated 20-amp line, and due to its power supply’s ability to deliver on an as-needed basis, and the massive dimming I witnessed when initially plugging this into a already loaded power circuit, I would provide this amp a solid power feed to get it to perform at its best.

I often found myself listening to this amp at higher than normal levels, due to the ease with which it reproduced volume and its ability to maintain its sonics at the highest of levels. At one point, I turned it down, as it was becoming painfully loud. Yes, this amp will play that loud if your speakers, and ears, can handle it, with seemingly absent heat production. While the TGA lacked some of the separation and air of some of the big boy amps, like Mark Levinson and Krell, it absolutely held its own and, in terms of absolute value, may be even better than the big boys when you consider dollar per performance. This Sunfire has power to spare and affords user adjustment of sonics to match your specific system needs with its two different types of outputs for the front speakers. Its slightly forward presentation worked extremely well for movies, giving a true theater-like experience, and it did a solid job with music as well. I found the TGA 7400 a solid performer offering flexibility and power not found in most amps, let alone seven-channel amps.

This amp can rock, which it proved to me, blowing me away during my extreme listening sessions to the point I found myself checking my speaker’s drivers for fear of damage. Thankfully, there was none, which is yet another testament to the clean power offered by the TGA 7400. This amp has amazing dynamic capability, and can run full-bore for hours on end without generating significant heat. I know some will find its $4,449 price tag high, but in the amplifier world, I assure you it is not. Factor in this amp’s amazing power production, flexible connectivity, small size, weight and the near absence of heat production, and you have one exceptional piece of gear that I am sure home theater enthusiasts as well as custom installer will love. While it weighs less than some speaker cables I own, it out-powered my expectations and made for fantastically real theater dynamics rarely seen in midrange, let alone high-end, home theater amplifiers. If you are looking for an amplifier to power your theater that can blow off your doors, and possibly your ears as well, this is an amp you need to hear.
Manufacturer Sunfire
Model Theater Grand 7400 Multi-channel Amplifier
Reviewer Ken Taraszka, M.D

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