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|Jeff's place - fishin' for steelhead
I've definitely got the hots for EveAnna's Tannoys. Man those are some cool speaks! But what about that Steelhead phono stage (or maybe it is more appropriate to call it the Steelhead phono control center because of its massive adjustability)? The Steelhead arrived at my place from EveAnna's place perfectly packed in a well designed and robust shipping carton, so it's my guess that shipping damage must be a rare event with Manley & Langevin electronics. My first impression of the Steelhead while unpacking it was ... like wow! The Steelhead has a high level of fit & finish and sports a robust build quality, and my oh my, that power supply is simply amazing and bigger than quite a number of amplifiers I've seen.
|But what about all of the front panel switches, buttons, knobs and stuff - what's that about? Let's do a little quick tour through the features. The big knob on the right side of the faceplate is the buffered volume control. The Steelhead can be used either as a phono stage that feeds into a preamplifier via direct outputs; or as a full function preamplifier with a line section that -- via variable output jacks controlled by the buffered volume control -- can drive power amplifiers directly. Note that if you want to use the Steelhead as a full-function preamplifier, there's only one set of line level inputs. If you have more than one line level source, you'll want to add the $900 Skipjack RCA switch box that provides more inputs and which Srajan reviewed. The Skipjack is an interesting studio-like device that allows 4-into-1 or 3-into-2 source selectors that not only provides more inputs but allows you to do A-B-X comparisons of interconnects and components.
To get a feel for the practical uses of the Skipjack, check out Marja and Henk's interconnect survey , where they used a Skipjack in the review process: "Ten pairs of cables arrived in our listening room, a completely random selection determined by availability. We used a Manley Labs Skipjack to perform A/B/X comparisons as accurately as humanly possible. The Manley Skipjack is a cable switcher managed by a microprocessor and a remote control to make for seamless -- and even truly blind -- switching." Sounds like a piece of equipment that would be useful for yours truly!
The Steelhead plus Skipjack is a very clever combination of equipment and is sure to find a following among studio engineers, reviewers, dealers and even hobbyists who want to do easy switching between gear and comparisons of gear. So for $8200 with a Skipjack, you can get a full-function preamplifier with multiple inputs and an amazing array of adjustability and comparability that makes it the most flexible preamplifier extant. The features included in the Steelhead plus Skipjack certainly makes the combination the benchmark for flexibility that all preamplifiers should strive to attain to. Can you imagine what it could do coupled with a 2-channel equalizer? It boggles the mind!
|But back to the buffered volume control: When using the variable output depressing the line button to the lower left of the volume control selects either the phono output or whatever is connected to the line input. The source signal then goes to the Noble potentiometer volume control, then to a high-current low-impedance vacuum tube White Follower output and to the variable outputs. EveAnna's preferred way to use the Steelhead is through the variable outputs to drive amplifiers directly.
Directly below the volume control is a button marked sleep that toggles the Steelhead between its normal operating mode and a low-power sleep mode. In sleep mode, there are no operating voltages except to the CMOS system control logic powered by a separate small mains transformer in the power supply.
To the lower left of the volume control is another button marked sum. When toggled, it combines the stereo into a binaural signal that routes to the variable outputs only (i.e. it doesn't work if you use the fixed outputs). According to the Steelhead's manual, this means that "monophonic or the lateral-only modulation content of your stereo records may now be heard. True mono may be experienced if the feed to one of your two loudspeakers is cut."
|Directly to the left of the volume control is another button marked dim to reduce the output to 25% of its previous volume setting, available again on the variable outputs only (no, it doesn't dim the front panel lights, my first guess before I read the owners manual). The Steelhead owner's manual warns that "the preamp specifications at the variable output may be slightly compromised with the dim feature engaged. This feature should be treated as a convenience for use when, for example, cueing up a record. System-menacing pops and thumps due to needle drop are held at bay yet sound from the pick-up may still be heard." The mute button completely silences the signal present at both the fixed and variable outputs.
At the center of the Steelhead's front panel is a 5-position rotary switch that allows you to select a cartridge load impedance of 25-50-100-200 or 400 ohms for moving coil cartridges, or 25-50-100-200 or 47K ohms for moving magnet cartridges. For moving coils, this works by switching between various taps on a "specially manufactured dual-primary bi-filar wound, high-bandwidth low-resistance and multiple-shielded nickel-core step-up autoformer" to transform the cartridges signal from a low-volt/high-current signal to a high-volt/low-current signal for better signal-to-noise ratio on the cartridge. This allows the user to hear the cartridge as intended at the load specified by its manufacturer.
Conversely, a load may be applied that the manufacturer didn't intend, in order to achieve a different tonal balance that suits your personal preference or system balance - a cartridge tone control if you will. As the Steelhead manual says, "The 'right' setting will ultimately depend on the cartridge in use, the type of music being heard, other downstream equipment and, most importantly, your personal preference. There will no doubt be moments when a technically 'wrong' setting will be musically 'right' for a given situation. Do rest assured that, in this instance, a technically wrong setting is completely harmless for all equipment involved."
|For moving magnet cartridges, the load switch selects between different fixed resistors in the values of 25-50-100-200 or 47K ohms. The Steelhead manual also says that "MM cartridges capable of properly driving low impedance loads between 25 and 400 ohms should be auditioned through both the MM and MC inputs. By doing so, you may find the most appropriate sonic character through the use of unconventional input arrangements. In short, experiment; don't let the control labeling stop you. On the contrary, we invite you to tweak away." So in short, twirl the knobs until you like the way it sounds. It doesn't get much easier than that!
To each side of the load switch are two switches for each channel. They allow you to select cartridge termination capacitance in 10 pF steps up to 1100 pico Farads. The manual explains that "the termination capacitance is present at the gain stage inputs and is not affected by input selector or gain switch changes. For best accuracy consult your phono interconnect cable literature or manufacturer to determine how much of the termination capacitance may be attributed to the cable. Then subtract at least that amount from the target capacitive termination value.
"If the interconnect manufacturer does not know the amount of capacitance per unit length that their wire presents (!), then refer to the following example for a starting point: Typical phono interconnect cables will exhibit self-capacitance on the order of about 30 pF per foot. If the interconnect cable is 3 feet (~ 1 meter) in length, you may expect about 90-100 pF of input capacitance present due to the interconnect cable alone. If the cartridge manufacturer specifies a load capacitance of 150 pF, then it is best to subtract the cable's portion, i.e. 90 pF. This yields a balance of 60 pF. Thus, the audition should start with the termination capacitance switches set to 60 pF." Got that?
|The idea behind all this adjustability is that each cartridge transmits maximum signal when loaded with a given amount of resistance and capacitance as specified by the manufacturer. When it is dialed in right, "the signal developed by the cartridge is at maximum power transfer into the preamp, with minimum overshoot and ringing, flattest frequency response and gentle roll-off characteristics." The Steelhead's manual recommends you start with the settings specified by the cartridge manufacturer (minus the interconnect capacitance) and then vary it until you like how it sounds. Unless you have it, you need not really know the settings for the cartridge. Just dial it by ear. The manual recommends that 150 pF is a good starting place as the standard "used by preamp manufacturers past and present."
The capacitance loading affects different cartridges in different ways depending on their design, but the general sonic attributes that will change are the imaging and spatial cues, the high-frequency content and the forwardness and speed of the sound. As we continue our march across the front panel, we encounter the input and gain selectors. The gain selector allows you to adjust the preamplifiers gain to match differing cartridge output levels and interconnect drive voltage requirements for long interconnect runs. The user can select from 50 to 65dB of gain in 5dB increments. The manual also says that the "MC step-up autoformer may provide approximately 2 to 12dB of additional voltage gain depending on cartridge source impedance and load switch setting." There are three separate phono inputs on the Steelhead so you can run multiple turntables or tonearms into it. There are two MC inputs and one MM input selected with the input selector located above the gain selector.
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