Krell FPB 700cx Stereo Power Amplifier 
Home Theater Power Amplifiers Stereo Amplifiers
Written by Augie Bettencourt   
Wednesday, 01 October 2003

In America, we love things big. We buy big houses, big vehicles and when we eat, we “super-size” our meals. We like monster trucks and enjoy watching big athletes play in the “Super Bowl” on our big-screen TVs. Therefore it’s no wonder that there is a market for huge audio amplifiers. For over 20 years, Krell Industries has been famous for making some of the biggest, baddest and most powerful amplifiers in the world.

The Krell FPB (Full Power Balanced) 700cx is Krell’s latest top-of-the-line amplifier in the FPB stereo amplifier line-up. The amplifier retails for $14,000 and is rated at 700 watts per channel into eight ohms, 1400 watts into four ohms and a whopping 2800 watts into two ohms. Having recently reviewed the Krell FPB 400cx, I was reminded of the Krell’s top build quality. Weighing in at 180 pounds and measuring 19 inches wide, 10.3 inches tall and 25.5 inches deep, makes the Krell FPB-700cx the title-holder for the most massive amplifier ever to grace my listening room. The 700cx’s large black anodized face and three small blue LEDs give the amplifier a very appealing, stately appearance. The front panel also has an infrared sensor for remote operation and interaction with other Krell products. The rear panel has two pairs of speaker binding posts per channel for bi-wire applications. These can be easily thumb-tightened, but they will not accept bare wire, banana plugs or pins -- only spade lugs will work. It offers balanced connections, as well as the proprietary Krell CAST™ inputs, which I’ll cover later in this review. The rear panel also includes the remote control Krell Link to turn the amplifier on and off, a very substantial non-detachable power cord, as well as a power breaker switch and a pair of handles to carry the beast around. Krell recommends a 20-amp circuit for this amplifier, which I was able to oblige.

As I unboxed the amplifier, I kept wondering how I would get this mammoth beast upstairs into my listening room. Fortunately, Krell supplies a packing system that includes handles, so that so that two people can lift the amplifier out of the box. Lifting the amplifier out of the box wasn’t difficult, although carrying it upstairs into my listening room was a different story. Once upstairs, I placed the Krell FPB 700cx on the bottom shelf of my rack and connected it to the Krell KCT preamp, via its CAST™ inputs. Speaker connections were made using the Cardas Golden Cross bi-wire speaker cables, which have long been my reference speaker cables. The Shanling CD-T100 CD player was used for all two-channel audio listening. For home theater viewing, the Krell FPB 700cx was connected to the Krell HTS 7.1.

The FPB 700cx is a Full Powered Balanced X Series Stereo Amplifier, which is what Krell calls their latest circuit design. The new X Series Amplifiers use the Krell Sustained Plateau Bias III microprocessor control system that maintains Class A operation, regardless of music or movie demands. Class A bias is the most accurate method used to amplify musical signals, but it has its engineering challenges. Class A operation means that all transistors in the amplifier draw current all the time. The large current consumption gives us one of the benefits of Class A operation, namely a distortion that is low and kind to our hearing. However, it’s a design that’s neither cheap nor easy to engineer, although it has obvious advantages. As I mentioned earlier in the review, the FPB 700cx has its own proprietary output design, called CAST™ Technology (Current Audio Signal Transmission), or in this case, CAST™ II Technology, Krell’s latest update. Krell claims the CAST™ II system improves every performance area, including speed, precision, dynamic range, depth and width of the soundstage, transient impact, tonal balance, harmonic distortion, and more. With the Krell KCT preamplifier on hand, I was anxious to try out the Krell CAST™ II system, something I couldn’t do during my previous review of the Krell FPB-400cx. Being a natural-born skeptic, I was looking forward to proof that the CAST™ II system was more than just hype.

Music and Movies
I started my listening session with the musical aphrodisiac and undisputed king of make-out music, the late Barry White from his The Best of Barry White: The Millennium Collection (Island-Def Jam). The first song I listened to was “I’m Gonna Love You Just A Little More Baby.” This song starts off with a pounding bass line that has never sounded tighter or more pronounced through any pair of Martin Logan Prodigies I have heard in my listening room, or any other listening room, for that matter. I was immediately struck by this amp’s ability to control the Prodigies with an iron-fisted grip, yet was able to convey the emotion in the rumbling, basso profundo of Barry White’s voice. It’s an intimate emotion rarely heard in an amplifier this powerful. What should be considered Barry White’s theme song, “Can’t Get Enough of Your Love, Babe,” is an upbeat little disco number that has never sounded more alive. The Krell drove the Martin Logan Prodigies with a control and force that I’ve never heard in my system before. Its sheer power was truly something to behold, as it always let me know it was in control at any volume level with extra power to spare.

The sometimes-haunting voice of Annie Lennox on “A Thousand Beautiful Things” from her Bare CD (J Records) seemed to float in front of the speakers, creating a broad, layered soundstage. It had a natural, organic sound. Lennox’s voice was as melodic as ever I’ve heard it and strings had excellent tonal quality. If I had to describe the sound of the FPB 700cx in one word, it would be transparent. This amplifier is as true to the source as any other I’ve had in my system and sounds completely uncolored. Lennox has the ability to sing with the most gentle, angelic voice ever heard in one breath and then sound like a dominatrix in the next. A perfect example of this is in “Pavement Cracks.” Lennox starts the song with a fragile voice before she builds to a crushing crescendo, which the Krell FPB 700cx handles without breaking a sweat. Its ability to scale dynamic peaks is unrivaled and unlike any other amplifier I’ve ever heard, no matter how much I pushed it. Its lack of compression and effortless sound is extraordinary and it can create a sense of sound and space like very few amplifiers can.

I don’t listen to classical music often, but the power and intensity of “Carmina Burana,” composed by Carl Orff and performed by the Atlanta Symphony from the Everything You Hear Is True CD (Telarc Digital), is astounding. It’s complete with choir and orchestra and is the piece that you hear almost every time you see a preview for an epic film. It’s both barbaric and very potent and conveys emotion like no other orchestral piece, especially when heard through the Krell FPB 700cx. This amplifier was made for “Carmina Burana.” As a matter of fact, it is “Carmina Burana.” It’s big, dynamic and dramatic. From the first kettledrum strike to the soft hush of the choir, the Krell produced the biggest, most powerful sound I’ve ever heard from my system. The Krell has a very quiet background but a very bold sound, so soft passages that become very loud passages can be startling. I found myself scrambling for the remote more than once. I tried hard to hear a sonic signature in the Krell, but it was never bright or soft, forward or laid-back, it just had a very big, honest presentation.

The first movie I watched was the critically acclaimed “Chicago” DVD (Buena Vista Home Entertainment). I’m sorry, but did I miss something? Yes, it sizzled and yes, it dazzled, but did it really deserve the Academy Award for Best Picture when it was up against films like “Gangs of New York,” “Road to Perdition” and “Lord of the Rings”? Regardless, the DVD is visually stunning and almost as impressive sonically. The Krell FPB 700cx made songs explode from the speakers, with clear, uncolored midrange and boisterous high frequencies. The bass response was tight and powerful and more effortless than I’ve ever heard in my listening room. Imaging across the front soundstage was terrific, with the dialogue, score and effects perfectly balanced.

The second DVD I watched was “The Lord of the Rings: The Two Towers” (New Line Home Entertainment). With its robust frequency response, this film offers an epic experience, with deep, rumbling lows to open, spacious mid-range and pristine high frequency response. The soundtrack is first-rate, balanced accurately against all the effects. The Krell FPB 700cx made the surging score by Howard Shore sound impressively impactful.

The Downside
Obviously, not everyone has $14,000 lying around to go out and purchase a two-channel amplifier, so the expense associated with purchasing this amplifier will prevent most from enjoying all it has to offer. Its size and weight could pose a problem for people who want to put this amplifier in a cabinet. Additionally, this thing can heat a small house on its own, due to its hot-running Class A circuitry.

Sonically, if you’re looking for a polite amplifier with decadent, tube warmth, this Krell is not be the best choice, but if you’re looking for an amplifier that’s very transparent and true to the source material, then this is definitely the amplifier for you. As with all Krell FPB amplifiers, this amplifier does not have single-ended or RCA inputs, which could prevent it from being compatible with some stereo preamplifiers. Possibly, this could require you to either purchase a new or different preamp, or possibly new cables as well. Krell recommends a 20-amp outlet for this amplifier and because this amplifier is a fully “Class A” amplifier, it’s like running a race car at full throttle while in use and could cause a slight increase in your power bill. The typical outlet is 15-amp service, which means this amplifier might facilitate the need to hire an electrician to upgrade your circuit, costing in the neighborhood of $300 (this is in Northern California dollars).

After lugging this truck-sized amplifier to my upstairs listening room, set-up was a breeze. By now, you also know how much I enjoyed the sound of the Krell FPB 700cx amplifier. I would have preferred it to have single-ended inputs, so that I could have tried a wider variety of preamplifiers, but the CAST™ inputs worked wonderfully with the Krell KCT preamplifier and I never felt like I was missing anything sonically.

For many listeners, this level of amplification could seem excessive. It’s like owning a 600 horsepower car. Most will wonder who really needs this. When it comes to amplifiers, there is no sonic equivalent to sheer power. It can supply the control and extension that will make your loudspeakers sing. Martin Logan speakers are notoriously difficult speakers to drive for most amplifiers, but with 1400 watts of “Class A” power into a four ohm load, the Krell FPB 700cx offered an incredible amount of headroom and what seemed like endless power reserves. Never did I feel the need for more power, and I also never felt that I was compromising sound quality for brawn. It was rather the opposite. Never have I heard an amplifier that could offer more delicate, extended upper frequency extension, open midrange, sound staging and the deepest, most controlled bass response I’ve ever heard in my system. Whether listening to the soulful voice of Barry White, the dramatic sound of “Carmina Burana,” or the epic experience of “Lord of the Rings,” this big, powerful amplifier never failed to impress me.
Manufacturer Krell
Model FPB 700cx Stereo Power Amplifier
Reviewer Auggie Bettencourt

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