World Premiere Review!
To tube or not to tube? Strange as it may seem, that age-old question is still relevant. Today new materials and innovative designs have taken vacuum tube audio components to a higher level. When I first saw the Black Ice Fusion F100 in room 504 at the Capital Audiofest, they were powered with Russian Tung-Sol KT150 beam tetrodes. This innovative tube is only one type of power tube the F100 can use, each with a different musical voice. This ability has a substantial fundamental advantage. Unlike solid-state amplifiers, you need not be stuck with one solid-state sound. Like a fine wine, the sound of vacuum tube audio components can appeal to many diverse tastes.
The Fusion F100 amplifier has an adjustable bias to accommodate a wide range of power tubes. Black Ice Audio offers a choice of output tubes. They can supply specific output tubes upon request with a new F100 purchase. The MSRP is based on the type of tubes you request: $7,800 with EL34, $8,450 with KT88, $8,200 with 6550, $8,650 with KT150, and $8,850 with KT170 output tubes.
The Back Story
I reviewed two of his inventions for Enjoy the Music.com in April 2017 including the JoLida Foz XT-R. It is an amplifier designed by Jim Fosgate to eliminate cross-talk between a phono cartridge's left and right channels. Later that year, in September of 2017, I reviewed the Jolida Foz SSX sound-stage "expander," another Jim Fosgate Invention. More to the point, I wanted to know more about this F100 Odyssey circuit. What to do? I decided to give Jim a call. He told me his wife wanted him to retire at age 84.
But retirement proved difficult. Because he still had so many innovative ideas that needed doing. So he set out to design a simple dual-stage amplifier with a "V" drive circuit. The concept evolved into what he now calls the Odyssey. It is a symmetrical push-pull design configured with low 4.5dB negative feedback. The amplifier has only two stages, an input and an output stage. The input stage uses a 12AX7 dual Triode in an SRPP configuration.
The circuit shown is a representation, not the actual F100 circuit.
Definition: What is an SRPP Circuit? It stands for Series Regulated Push-Pull amplifier. This circuit promises the advantages of both the Grounded Cathode amplifier and the Cathode Follower with high gain and low output impedance. Two tubes act as a single-stage, close to push-pull. The overall odyssey design is a fully balanced differential push-pull circuit able to direct drive the output stage.
This circuit design has high gain, low distortion, and low output impedance so that the output tubes can be driven directly with no buffers. Jim stated that he uses second-harmonic cancellation to stabilize feedback. This is done by adjusting the SRPP bias so he can keep negative feedback to 4.5dB. He prefers the same type of transformers used in the old Dynaco ST70 amplifier. The Dynaco transformer was designed and patented by David Hafler. The German sourced silicon steel transformer lamination's are based on that Hafler design. This patented Hafler section was incorporated in the Jolida transformers. After some searching, he managed to find a Chinese company that makes a similar transformer.
I asked Mr. Fosgate if he was going to patent his Odyssey design. He said he didn't design the amplifier just to make money. He doesn't plan to publish a circuit schematic of the amplifier. His sole intention is to squeeze every bit of performance out of the amplifier for a reasonable price. He designed a two-stage amplifierwith a simple circuit and fewer internal parts to accomplish this. His designer's repertoire spans every category of electronic audio from two-channel audio, car audio, surround sound, headphone amplifiers, and digital audio. Mr. Fosgate's resume of audio innovations is truly remarkable.
The Chinese sourced Hafler designed silicon steel transformers are enclosed in an attractive rectangular cover made with silver foil-backed glass. The review amplifier's surface has a matching soft silver color, but you can order the amplifiers in a black finish. Directly in the center of the amplifiers top surface is a round D' Arsonval bias meter with a scale marked in milliamperes. Occasionally you will need to adjust the bias settings of the four output tubes.
To set bias there is a five-position selector switch marked Off, V1, V2, V3, and V4; they allow you to select one of four bias trim-pots. Black ice audio provides a small screwdriver for this purpose. The Odyssey Circuit, designed in 2015, is a dual-phase balanced V drive circuit. With EL34 power tubes, it pumps out 120 Watts of pure tube magic. With KT88 tubes or 6550 tubes, the available power is increased to 140 Watts.
The back panel of each mono-block has an IEC socket for the power cord, a master on/off power switch, and three speaker cable binding posts. They are marked as Ground, 4 Ohm, and 8 Ohm speakers. Very unconventionally, there are two RCA input jacks and three XLR jacks. So you have a choice to input either balanced XLR or unbalanced RCA cables from your music source. An unconventional feature is the ability to combine two F100 mono amplifiers to double the power output to 280 Watts. It is straightforward to strap two amplifiers together since they have both input and output jacks. You would need one XLR cable and one RCA cable to connect the two. When it's time to kick it up a notch, the F100 can be bridged with another F100 to double the wattage and experience music at concert levels.
That doubled-up combination can be expensive since a stereo system would require four Fusion F100 amplifiers.
The 12AX7 tubes have a nine-pin base. The corresponding ceramic tube sockets are high quality and hold the tube pins in a very tight grip. You need to be careful that all the pins of the tube line up precisely with the base sockets. You will need to use some force to seat the tube. My first three attempts resulted in bent tube pins and one cracked glass tube.
There is a two-step process to turn on the amp. Once you have installed the tubes, activate the main power switch on the back panel. Next step, there is a capacitive touch sensor power switch in the center of the front panel which is not visible. The Black Ice logo will light up in red with a light touch on the faceplate, then the amplifier will turn on.
There is a delay of about ten seconds for the amplifier to power on. At this initial turn on, check and set each of the four bias trim pots to specification. Then, after the amplifier has played for approximately twenty minutes, perform an additional check to see that the tube bias is stable at 50mA. You will need to play music through them for approximately two or three hours to ensure the tubes have settled in and stopped changing. I advise you to periodically check tube bias; properly set it has a big effect on what you hear.
Back in the day, whenever a musical overtone decayed in volume/loudness, it reached a cutoff point, and digital volume controls could drop the least significant bit. With this amplifier, nothing I hear is in pieces; nothing goes on and off. It is, as HP said, "continuousness."
Even while streaming piped in Pandora music, you can plainly hear the sound of the Odyssey singing songs at you from the very first moment.
To fully appreciate what the Odyssey amplifier does, you should want what tubes do best, image! It is possible to craft an audio system that paints a sound stage that can turn your room into a performance space and not just between your ears. Vacuum tubes will reproduce all three realistic dimensions, including height, something that ear-bud gizmos just don't do. Did you ever surprise yourself by finding something you forgot you owned? I normally use an album's CD version as a reference.
This discovery is Basia Trzetrzelewska's vinyl album, Time And Tide Epic [BFE 40767]; damn, this woman can sing. I played the album's first track, "Promises" ,wonderfully dynamic with a tremendous driving tempo. What a very complex multi-layered vocal and instrumental score this is. It seems to me that tubes and vinyl recordings have a particular, very logical affinity to each other. Everything I hear has an organic tone color. I seriously considered stopping right here and not describing anything more about this performance. But there is still one more test it has to pass.
The 6550 Audition
I saved the best for last as I tell you the tale of a vinyl interlude. It involves a favorite recording, Another Page, by Christopher Cross [Warner Brothers 23757-1]. You may not own this recording. But as the British say, "needs must" because this is the moment something rare happens. At this juncture, it's one of those moments where a paper publication might proclaim, a veil was lifted. Another Page is an excellent studio effort filled with small aural clues. As I listened to the track All-Right, I could hear the background singers far better defined as separate entities.
Now clear to hear are individual voices that are separated by space and timing clues. The singer's voices contained reverberate studio effects overlaid by a second delayed echo. Both effects remained separate, and clearly, each would start and stop at different times. I could pick out most of the individual backup singers. This recording has Michael McDonald, Carl Wilson, Don Henley, Art Garfunkel, and J. D. Souther, all singing back up vocals. I have played this album so many times before but never got this deeply into it. The hardest thing to describe to you is the envelope of air, like a dimensional halo that formed in the space between my speakers. Because of this, I can better understand the way this album was mixed down from separate tracks.
Ultimately we strive to gain a clear insight and a sense of intimate personal involvement in the music we play. This is the light at the end of the audiophile tunnel. The Fusion F100 is a world class amplifier that you need to audition.
Remember to Enjoy the music and from me, Semper Hi-Fi!