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Product Review
 

Sunfire Cinema Seven Signature Edition 400 Watts x 7 Home Theater Power Amplifier

November, 2003

Kris Deering

 

Click on the Photo Above to See a Larger Version

Specifications:


Power: 400 Watts RMS x 7, 20 Hz -
    20 kHz

THD: 0.5%

MFR: 1 Hz - 80 kHz
Current Source and Voltage Source
    Outputs

XLR and RCA Inputs
Size: 6.5" H x 19" W x 15.75" D

Weight: 52 Pounds

MSRP: $3,995 USA

 

Sunfire

www.sunfire.com

 

Introduction

I first became aware of Bob Carver and his Carver products back when I was in High School overseas. The only affordable source of electronics was the Exchange on base and needless to say, the selection was very limited. Mainly you could choose from some very low end receivers at the time. But this wasn’t really the era of affordable home theater.

The Exchange did carry a few select products that were a bit better then the norm though. For speakers there were some nice offerings from JBL. But for components, the only higher end example was Carver. I personally couldn’t afford it on my Burger King salary at the time, but I had a friend who was using Carver separates to power a pair of Bose 901s which at the time were the elite, well at least to my limited knowledge.

As most of you know, Bob went another direction later and established a dedicated line of home theater products under the name Sunfire. The Carver line is still produced, but it deals mainly with commercial applications, or so I’m told.

Under the Sunfire line came some very well regarded processors and amplifiers featuring some seldom used technologies, even by today’s standards. Bob has carved somewhat of a niche market with his designs, and we at Secrets have truly admired his efforts since our start. His processors and amplifiers have received a lot of praise from our reviewers and rightly so.

For this review, I was sent the new Cinema Seven Signature Edition amplifier. This amplifier is similar to Sunfire’s previous offerings in that it uses a Class D switching power supply, making it very efficient. It is also a workhorse of rare breed offering an unprecedented 400 Watts per channel into no less then seven channels, all channels driven!! This kind of power is an extreme rarity unless you’re looking at products the size of end tables with enough heat output to keep an Alaskan town warm. What is even more amazing is the fact that the amplifier doubles its output each time you halve the load impedance. Sunfire claims this amplifier can actually produce 1,600 Watts per channel into 2 ohms on a limited time basis. I was unable to test this theory, as I don’t have any 2 ohm speakers hanging around, unfortunately.

The Design

As we have mentioned in previous reviews of Sunfire’s amplifiers, this kind of power is due to the tracking down converter Bob has developed. Most amplifiers keep their rail voltages at a constant level, so unused voltages can create a heat buildup. The Sunfire takes samples of the signal voltage and keeps the rail voltage just slightly above that.

During dynamic shifts, the voltage may have a hard time keeping up. But the Sunfire sounds excellent, and I never heard any noticeable distortion in my time with the amplifier.

Another advantage to digital switching amplifiers is cost. Sunfire’s designs give you incredible amounts of power without an incredible price tag, and the Cinema Seven Signature will drive any set of speakers you might have, including electrostatics.

The Cinema Seven casing is machined aluminum and is roughly the dimensions of most processors. The front panel features a meter that indicates the current joule rating of the capacitors. This gives you an idea of the stored power the amplifier has. The meter is illuminated and gives the amp a bit of an old fashioned look. The lighting is adjustable so those looking for absolute lighting control in their room have no worries. For the Signature Edition the meter reads 480 joules. I never once saw it drop below that at any time, even while running my setup at full reference levels.

The back panel has a very nice layout, making connections fairly easy. The binding posts are 5-way and are very solid. Each input features three connection options, two RCA unbalanced and one XLR balanced. The Sunfire is not a truly balanced design but if your processor has XLR outputs, you can use them with the Cinema Seven.

Click on the Photo Above to See a Larger Version

Like previous Sunfire amplifiers, you have a choice of voltage source or current source outputs, selectable by choosing which set of speaker binding posts you connect to. The principle is based on classic tube amplifiers being current source by design. According to Bob, this gave them their trademark sound, which was warmer and a bit more full bodied than the voltage source designs of most solid state amps used today. Bob wanted the flexibility of offering a choice depending on your taste in sound. Those with electrostatic or ribbon speakers may opt to use the current source connection, while others may use the conventional voltage source outputs. You can also drive separate parts of your speakers with the different output types, e.g., drive the woofers with the voltage source and the tweeters with the current source. This is the recommendation Bob gives for setup in the manual, and I gave it a try. I’ll talk more about that in the listening section of the review.

Last up on the back panel is the power switch, which has settings for On, Off, and Auto. Auto will turn the amp on when it senses a load. This was the setting I used most of the time and the delay once a signal is detected was only about 1-2 seconds. There is also a 12V trigger input so that the amplifier can be powered on from a processor or receiver.

The amplifier comes with a glass plate for placement underneath. This plate has more functions than just looks. First it allows proper room beneath the amp for ventilation. It also serves as a vibration damper for those choosing to set the amp on a component rack.

The Sound

I started my listening for the first week or so with strictly home theater use. I wanted to break the amp in a bit with more dynamic tracks and then work into music. The amplifier I was using prior to this one was the Krell Showcase amp which I found very satisfying.

The Sunfire actually upped the ante a bit with film soundtrack reproduction. The soundstage increased a bit and the amp seemed to give my speakers a bit more transparency then the Krell did. This may be attributed to the power increase, as the Sunfire has more then double the power. The Sunfire never so much as batted an eye at any DVD I threw at it. This is pretty much what I would expect as my speakers are fairly efficient (92 - 93 dB) and only a 6 ohm load. I also have them crossed over at 80 Hz providing a relatively simple task for an amplifier of this magnitude.

The Sunfire has a relatively high distortion rating compared to most Class A/B amplifiers due to its tracking design (0.5% THD). This never appeared to be a problem, as the amp sounded every bit as good as anything I had heard before it. The soundstage was rich, powerful, and very transparent. It continually impressed me regardless of genre and sound design, enough that I started conspiring how I could get my wife to agree to let me add it to my system. This is an amplifier that I would easily consider as a reference piece in a home theater system.

After a week or so, I started delving more into music, both multi-channel and stereo listening. The Sunfire provided a spectacular sound that was very neutral and very engaging. Most of my listening involved high resolution DVD-Audio, and the Sunfire performed brilliantly. I never heard any audible coloration in the midrange, and the higher end of the spectrum sounded very detailed and rich.

After listening to music for a few days, I decided to experiment with the different output configurations of the amplifier. At first I drove the speakers using the standard voltage source outputs. This provided the sound I was more accustomed to and was by far my preferred setup. I thought the amplifier performed its best in this configuration especially in the low end. When driving my speakers full range with two-channel material, this configuration provided the most dynamic experience with tighter more detailed bass, and was evident more in jazz and hard rock. Kick drums and lower bass notes had more report to them. However, this area is the only spot in which I thought the Krell outperformed the Sunfire. The Krell had a low end that was extremely impressive. Using the Krell with my speakers resulted in bass that would almost make a subwoofer unnecessary. The Sunfire did provide plenty of low end power; it just wasn’t quite as involving as the Krell was. But this wasn’t much of an issue with me, as I rarely ever run my speakers full range.

When I switched to current source, I immediately noticed the change in tonal quality. This mode is used to coax a more tube-like sound from the amplifier. It did offer a slightly more laid back sound, but it wasn’t really to my liking. I found the lower end a bit too subtle. There have only been a few times that I have preferred a tube sound, and that is mainly in guitar amps with certain types of music. A good example of this is Eric Johnson’s music. The richness of his playing is fully complimented by the tube amplifier he uses.

I also tried using the voltage source for the woofers and the current source for the tweeters. This was more enjoyable than going all out current source. The soundstage was more defined, and the lower end regained the tighter more pronounced feel. This was more apparent in music playback than film soundtracks though. While I did prefer straight voltage source overall, I love the idea of offering the end user a choice and leaving it up to his/her ears.

Conclusions

Sunfire has yet again produced an excellent amplifier that sets a new benchmark for price/performance. I was very reluctant to give the amplifier up at the end of the review, as I had really enjoyed my time with it. It is easily the best amplifier overall that I have had the pleasure of having in my system. For those looking for extreme power and excellent sound, this is an amplifier you should definitely audition.


- Kris Deering -

 

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