Seta
®
Balanced Direct Coupled Ultra Wide Bandwidth
Phono Preamplifiers
Seta Phono Preamplifier (Model L / Model H). Click for back view of preamplifier with optional internal RIAA correction module, featuring simultaneous Flat and RIAA outputs.
| Seta phonograph preamplifiers provide the users of Channel D Pure Vinyl software with an end-to-end route to the superb performance obtainable from "flat" vinyl reproduction (linear amplification followed by software RIAA correction). Seta preamplifiers offer a fully balanced (from input to output), low-noise, direct coupled (DC) differential circuit design, with an unprecedented (5 MHz) signal bandwidth, even at high gain settings. |
- "Flat" Phono Preamplifier; perfect for use with Pure Vinyl software RIAA correction
- DC to 5 megahertz (- 3 dB) bandwidth (Model L), unprecedented for a phono preamplifier, delivers stunning improvements in smoothness, clarity, definition and 3-D imaging
- Optional, precision (± 0.1 dB) RIAA Correction provides simultaneous "Flat" plus RIAA Corrected, independently buffered and balanced (XLR) and single ended (RCA) outputs
About Seta: Listening evaluations using a variety of reference systems and program material show that an important key to accurate reproduction of vinyl audio involves greatly increasing the signal bandwidth of the preamplifier front end (the first stage of amplification touching the signal from the phono cartridge).
Why? High quality phonograph cartridges are capable of reproducing signals well over an octave above the audio range.
While such signals are inaudible, the preamplifier also must work to amplify these signals, which also are boosted over 20 dB above midrange levels (because of the standard vinyl treble pre-emphasis curve used in the mastering process). A preamplifier unable to handle out of band signals will distort in the ultrasonic region. This distortion will carry over into the audio range, affecting the reproduction of the midrange and treble.
Futhermore, the audibility of one of the most maligned deficiencies of vinyl, those irritating "pops and clicks," is a function of and can be exacerbated by the design of the preamplifier. The reason is that the transient signals caused by the stylus striking a scratch or foreign object in the groove have, in addition to large amplitude, a very fast risetime, and are unlike any musical signal. The fast risetime can cause slewing distortion in traditional narrow bandwidth or inexpensive phono preamplifiers, magnifying the audibility of pops and clicks. It's quite possible that this nonlinear coloration from a less capable preamplifier is at least partially responsible for causing many music lovers to shun recordings in the vinyl medium! The Seta wide bandwidth design employs a fast-responding front end gain stage with a slew rate of over 500 volts per microsecond (Model L), making it immune to transient distortions induced by pops and clicks, minimizing their impact on the listening experience. (The slew rate of the Seta output is deliberately limited to avoid causing slew rate distortion in any following components.)
How much bandwidth is enough? The rule of thumb for linear signal reproduction is ten times (an order of magnitude) greater than the signal of interest. With that criterion, the amplifier is able to linearly reproduce out of band signals, while preserving the integrity of the midrange and treble without the "haze" caused by, and characteristic of, ultrasonic intermodulation distortion. Going still further, extending the bandwidth by two orders of magnitude, delivers a stunning improvement in three-dimensionality and imaging.
| Feature | Benefit |
| Ultra-wide linear signal bandwidth (-3 dB at 5 MHz; Direct Coupled circuitry, No Capacitors in signal path) | Improved Smoothness, Clarity, Definition and 3-Dimensional Imaging |
| Fully Balanced, Complementary Circuitry | Reduced Noise and Distortion |
| Minimum Signal Path Design | Preserves Signal Integrity |
| Low Impedance AGM Internal Rechargeable Battery | 20 Ampere Peak, Deep Power Reserve Preserves Signal Dynamics |
| FET or Bipolar Hybrid Circuit Topology | Performance Tailored to MM or MC Cartridges |
| Video Bandwidth, Balanced Low Impedance Output Amplifier | High Noise Immunity; Not Affected by Connected Equipment or Length of Output Interconnect |
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| Seta preamplifier's hybrid, video - bandwidth amplifier modules are electronically and acoustically isolated and kept at a stable operating temperature and environment (constant humidity) by enclosing and sealing them in a block machined from a solid piece of oxygen-free high conductivity copper. Each module is carefully tested and characterized before and after being hermetically sealed in the copper block. | |
Circuit Design: The Seta front end circuitry is tailored to preserve the strengths of the characteristics of different cartridge types. A low noise, high impedance FET front-end is used in the Seta Model H for moving-magnet and other high output cartridges, while an ultra-fast, ultra low noise bipolar transistor front end is used in the Seta Model L for low impedance, low output moving coil cartridges.
The circuit topology is fully differential, balanced direct-coupled circuitry from input to output. The front-end active circuitry is surrounded on five sides by a sub-enclosure machined from a solid block of copper. This provides electronic and acoustical noise isolation plus thermal stabilization. Bare copper metal surfaces are coated with a clear lacquer to prevent oxidation (and to maintain their beautiful color).
Unlike many other preamplifier designs: the rated (-3 dB) bandwidth is independent of gain.
Rechargeable Battery Power Supply: The low-impedance, internally located AGM rechargeable battery is capable of supplying over 20 amperes of peak current, outperforming other types of batteries used in audio applications. The battery is conditioned and kept float-charged by a proprietary, uniquely designed rail balancing circuit, rather than use an "off the shelf" microprocessor based conditioning and monitoring circuit, which would introduce unwanted noise. Locating the battery inside the preamplifier chassis also insures that the battery is in the same electrical environment as the sensitive front-end circuitry, eliminating potential sources of noise pickup. The external charging supply is automatically disconnected when an input signal is detected.
Mechanical: All connectors are the best available, professional quality Neutrik gold contact XLR, premium Switchcraft TRS and WBT gold contact helical conductor wide bandwidth RCA.
Pushbutton actuated, sealed gold contact small signal relays are used to change gain settings (four different gain settings). A unique rear-panel (optionally on front panel) rotary balance trim control with a precision 2 dB range provides for fine cartridge channel balancing (the setting of trim control is not affected by the overall gain).
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| (Left) Interior Close-up View of Seta, showing Solid Copper Front-End Circuitry Isolation Block; (Right) New Seta Model L / Model H Preamplifier Modules | |
Seta Wide Bandwidth Direct Coupled Balanced Preamplifier Product Line:
- Seta Model L for Low Output Moving Coil Cartridges (Bipolar Hybrid, DC to 5 MHz bandwidth, < 0.001% THD 10 Hz - 40 kHz)
- Seta Model H for High Output (Moving Magnet, High Output Moving Coil) Cartridges (FET Hybrid, DC to 1 MHz bandwidth, < 0.007% THD 10 Hz - 40 kHz)
- Seta RCM RIAA Correction Module (simultaneous Flat and RIAA Outputs) for Model L or Model H, < 0.001% THD 20 Hz - 20 kHz)
- Seta Nano for Low Output Moving Coil Cartridges (Monolithic IC, DC to 3 MHz bandwidth, < 0.02% THD 20 Hz - 20 kHz)
Features:
- Delivers stunning improvements in sound staging, detail and 3-D imaging (compared to other preamps)
- Fully Balanced, Complementary Design from Input to Output; can be used with balanced or single ended turntables and other equipment
- Pure Linear, Straight-Wire Signal Gain, designed to be used in conjunction with Pure Vinyl software and A/D Interface (for RIAA curve correction)
- Software RIAA Correction Eliminates the need for Capacitors in the Signal Path (except for the adjustable cartridge termination on Model H/MM input)
- Circuitry Optimized For Cartridge Type (Bipolar for L/MC; FET for H/MM)
- Gain Settings (Seta Model L/H) are accessible from front panel
- Load Settings accessible from rear panel
- Solid copper shielding and temperature stabilization block (Seta Model L/H)
- Premium, precision components in signal path (0.1 % metal film resistors; silver mica and metallized polypropylene film cartridge loading capacitors)
- Rechargeable battery powered (low impedance AGM type, with peak output current capability of over 20 amperes, Seta Model L/H)
- Designed and Assembled in U.S.A.
Specifications - Seta Phono Preamplifiers (Model L, H)
| Of course, the "last word" in the evaluation of audio products should be done by using the best "measurement:" real-world, listening-based evaluation. However, we believe that careful measurements also are essential, if only to insure that the product you receive actually conforms to the designer's original vision and intent. |
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| *Note: If you're accustomed to using conventional phonograph preamplifiers, the available Seta gain settings may seem somewhat lower than usual. However, they are tailored to using the Seta with Channel D Pure Vinyl's digital vinyl compensation curve. The required gain is about 10 to 12 dB less than needed in a conventional phono preamplifier, because the signal is provided to Pure Vinyl with treble emphasis (boost) intact. (For the technically knowledgeable: this turns out to be somewhat less than the maximum 20 dB correction of the RIAA compensation curve at 20 kHz, due to the frequency balance of most music.) For example, if you would normally use a preamplifier gain of 40 dB for a moving-magnet cartridge, then the proper setting on the Seta would be 29 dB (or perhaps 35 dB). Likewise, the optional RIAA hardware compensation module provides an additional 12 dB of gain (at 1 kHz). |
Internal RIAA Compensation Module,
shown installed in Seta Model L.
Specifications - Seta Optional Hardware - based RIAA Correction Module Specifications - Seta Nano Phono Preamplifier Dimensions Warranty
