Prior to 1954, when the RIAA curve was adopted by the recording industry as the de facto standard, there were dozens of equalization (EQ) curves in use. Some were standardized in-house by label, while others were improvised on the spot by the recording engineer. For the vintage LP and 78 collector, restoring the EQ curve that matches the original recording is critical to enjoying the music as it was intended to be heard. A few widely used settings were often included in hi-fi components from the 1950s, but deviations from the RIAA curve are rare in modern gear. The Tempo Electric Universal Mono Preamplifiers change all of this by incorporating the most comprehensive choice of user friendly EQ settings available today.
EQ playback curves consist of two major parameters — the Bass "Turnover" frequency and the 10kHz Treble "Roll-Off" value. They define a bass boost curve with a 3dB cutoff or "corner" frequency at the Turnover point and a Roll-Off or "cut" curve which reduces the gain above a certain point, so that the gain at 10kHz equals a specified value. Note that some 78 EQ curves have a 10kHz Roll-Off of Zero dB, meaning that they are flat at the treble frequencies.
The audio circuit was designed by Dr. Arthur Loesch (pronounced "Lesh," like the Grateful Dead's Phil Lesh). It's the same design that was the basis of the now-discontinued Arthur Loesch 1.1 Control Preamplifier which was rated "Class A" by Art Dudley in Stereophile and about which the Bound For Sound Audio Report devoted two extensive reviews. However, the original circuit has been modified with the addition of variable bass (Turnover) and treble (Roll-Off) filters, for which Dr. Loesch calculated the values. With 12 bass and 12 treble restoration points, a total of 144 different equalization curves (including RIAA) are possible. With the right combination in place, vocals and instruments are fully restored to their proper balance. In the world of 78s, there is also a low bass setting called Shelf which is fixed at 50Hz.
| Bass Turnover Switch Position | Bass Turnover Time Constant | | Treble Roll-Off Switch Position | Treble Roll-Off Attenuation @ 10kHz |
|---|
| A | 0Hz
Acoustic | 1 | -0dB
Acoustic |
| B | 150Hz | 2 | -5dB |
| C | 200Hz | 3 | -7dB |
| D | 250Hz | 4 | -8dB |
| E | 300Hz | 5 | -8.5dB |
| F | 350Hz | 6 | -10dB |
| G | 400Hz | 7 | -10.5dB |
| H | 450Hz | 8 | -11dB |
| J | 500Hz | 9 | -12dB |
| K | 629Hz | 10 | -12.7dB |
| L | 800Hz | 11 | -13.7dB |
| M | 1000Hz | 12 | -16dB |
For your convenience, each switch has a corresponding letter or number code that makes it easy to annotate your records. For example, a record cut with the RIAA curve can be noted as "J 11," Okeh 78s can be labelled "D 4," early Blue Notes "J 7," and so on. A comprehensive guide to 78 RMP EQ settings and disk speeds, as well as a guide to early LP EQ settings is periodically revised to suggest these settings. Of course, you can always make adjustments by ear.
The Sound
In voicing the phono circuit, unamplified music, recorded in a live environment, rather than in a studio, was used as the primary reference. The result is a natural, well-balanced sound. If the details are on the disk (or disc) and the rest of your audio system is on par, you will easily hear nuances that were previously hidden. These include those unique, low-level cues which distinguish individual recording spaces from one another — even on mono 78s. The lack of a sonic signature produces a sound that is notable for its natural bass, glare-free treble, and rich, detailed midrange. In addition, there is an uncanny degree of clarity plus "air" which enables you to follow every individual instrument or voice with ease. With associated equipment of equal quality, the audio hardware disappears, leaving you alone with the performers themselves.
The Circuit
The phono circuit amplifies the audio signal in three gain stages and is suitable for any cartridge with an output of 0.1mV (or lower) up to 7.5mV, moving coil or moving magnet. 12 popular cartridge loading resistor values can be dialed in from the front panel and a custom cartridge load is possible via spring-loaded, plug-in sockets, located on the main board next to the phono inputs. The standard, front switched phono load values can also be replaced with custom values.
Custom Phono Load Sockets
Moving Coil or Moving Magnet (Moving Iron)?
The original Loesch high-gain (+60dB) phono circuit was designed exclusively for low-output moving coil cartridges, eliminating the need for a step-up transformer or pre-preamplifier. Due to the popularity of high-output cartridges, an additional low gain (+40dB) circuit is now included with both the Panorama And Monograph preamps. The Panorama models also include a tube-based (+14dB) active line stage.
Economy or Premium?
When our listening panel first heard the version built with economical, high quality parts, they did not know it wasn't the version built with premium parts which they had been listening to for the past decade. Dr. Loesch's circuit design is so well thought out, that you will barely notice the difference yourself. For the perfectionist, who lies awake at night wondering if the electrons are happily flowing in the right direction, the Premium and Silvermine models offer the Last Word in phono reproduction. However, it's not hyperbole to say that the basic builds offer better than 90% of the sound quality of the upgraded, "cost no object" versions.
Not Just For 78s!
The Universal Mono Phono Preamplifiers are all based on the same circuit board and only vary in their size, features, parts build, and power supplies. The ability to customize gives you a unique opportunity to own a reference quality phono preamplifier that restores the sound of any recording to the way it was originally intended to be heard. While first developed for 78 RPM collectors, listeners with large collections of pre-1954 (and later) mono LPs will enjoy the benefits of proper EQ, as well. A pair of Universal Mono Preamplifiers, with their separate, dedicated power supplies, will bring a lifetime of enjoyment from modern stereo recordings, too.
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Models
The Universal Mono units are available in five different versions: the phono only Monograph and Monograph Premium, the Panorama, Panorama Premium, and Panorama Silvermine. The Panorama models are (full function preamps that include two passive line inputs and one active line civuit.
These are not "phono stages," but complete phono-based preamplifiers. While you can use them with the passive or dummy input of a line stage or other preamplifier, they are designed to be stand-alone units that connect directly to your power amplifier(s). They will not sound right when their output is fed into an active line stage.
Monograph Mono Preamplifier
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The MonographTM mono phono-only preamplifier is the simplest and most economical version. It's based on the concept of "Phono In, Phono Out" and comes with a separate, tube rectified power supply. The slow turn-on protects the entire circuit and helps to extend tube life. It represents the minimum requirements for a high quality, dedicated phono system.
Features in the Monograph include:
- Your choice of a 3-stage High Gain (+60dB) phono circuit, suitable for use with any moving coil phono cartridge (0.05mV-2.0mV output) without a step-up transformer and a 3-stage Low Gain (+40dB) phono circuit, suitable for most Moving Magnet or Moving Iron cartridges (2.5mV-7.5mV output)
- Two selectable phono inputs
- 100 ohm and 47K ohm phono load resistors, selectable from the front panel
- Provision for a custom phono load resistor in any value, including fractional values
- Variable cartridge capacitance loading from 50pF to 350pF in 50pF steps (custom values on request)
- Kimber Ultra-PlateTM RCA Sockets
- Two Main Output sockets, wired in series, so that mono signals can be played on a stereo system
- A Record Out socket that bypasses the volume control for recording the output signal to another device
- Double-thick, 0.125" circuit boards with extra heavy traces for low internal resistance
- Pure silver, Teflon-insulated signal wire throughout the audio stage
- Heavy gauge, Teflon-insulated, silver-plated copper wire throughout the power supply
- 120V/60Hz and 240V/50Hz switchable voltages for world-wide use
- 15A Male IEC connector on the power supply for use with custom and worldwide power cords
- All units are assembled by hand in our workshop in Troy, NY, with 95% of the parts sourced from USA and European manufacturers
Monograph Power Supply (Concept)
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Features in the Panorama include:
- A 3-stage High Gain (+60dB) phono circuit, suitable for use with any moving coil phono cartridge (0.05mV-2.0mV output) without a step-up transformer
- A 3-stage Low Gain (+40dB) phono circuit, suitable for most Moving Magnet or Moving Iron cartridges (2.0mV-7.5mV output)
- A Plate Voltage Adjustment control, with dedicated panel meter, for the first stage tube
- Three selectable phono inputs (up to 6 phono inputs are possible)
- Front panel selectable cartridge loading resistors in 12 popular values
- Provision for a custom phono load resistor in any value, including fractional values
- Variable cartridge capacitance loading from 50pF to 350pF in 50pF steps (custom values on request)
- Two Passive Line inputs (no gain circuit) connected directly to the volume control
- One Tube Active Line input with 14dB of gain
- Kimber Ultra-PlateTM RCA Sockets
- Two Main Output sockets in series, so that mono signals can be played on a stereo system
- A Record Out socket that bypasses the volume control for recording the output signal to another device
- Double-thick, 0.125" circuit boards with extra heavy traces for low internal resistance
- Pure silver, Teflon-insulated signal wire throughout the audio stage
- Heavy gauge, Teflon-insulated, silver-plated copper wire throughout the power supply
- 120V/60Hz and 240V/50Hz switchable voltages for world-wide use
- 15A Male IEC connector on the power supply for use with custom and worldwide power cords
- All units are assembled by hand in our workshop in Troy, NY, with 95% of the parts sourced from USA and European manufacturers
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The upgraded Panorama PremiumTM package includes these additional features:
- A Western Electric 417A First Stage tube, specially selected for low noise and low microphonics
- Premium parts throughout including "Naked" Vishay TX2575 resistors, Audio Note Tantalum resistors, V-Cap Teflon capacitors, and Caddock MS series power resistors
- Copper Foil coupling caps following each stage: V-Cap Teflon Film & Copper Foil, REL Polypropylene Film & Copper Foil, and Jupiter Paper & Wax Copper Foil, respectively
- A ladder-type stepped attenuator built-up with Vishay-Dale axial resistors, based on a Swiss-made Elma switch
- WBT NextGen Ag Pure Silver RCA sockets
- The Arthur Loesch designed 1201B+ tube-rectified and tube-regulated power supply
 1201B+ Power Supply |
| Specifications: Universal Mono Preamplifiers |
|---|
| Monograph and Monograph Premium Audio Stages |
| Gain | +60dB MC Phono
+40dB MM Phono |
| Tube Complement (Vintage NOS USA or UK tubes supplied) |
| 1st Gain Stage | Raytheon 5842 (Monograph) or Western Electric 417A (Monograph Premium) | /TR>
| 2nd Gain Stage | RCA 6GK5 / 6FQ5A |
| 3rd Gain Stage | Tung Sol 5687 x 2 |
Inputs:
| Phono x 2 |
| Outputs | Main Out x 2 in Series
Record Out x 1 |
| EQ Filters | Treble (12-position "Roll-Off")
Bass (12-position "Turnover")
Deep Bass ("Shelf" fixed at 50Hz) |
| Frequency Response | 5Hz - 50KHz |
| Phono Input Impedance | A front panel switch allows the selection of either a 100 ohms or 47K ohms Phono Load resistor. On request, any other value(s) may be substituted. In addition, an internal spring-loaded socket accepts any custom value Vishay TX2575 or Caddock MK132/MK232/MK232 resistor. |
| Phono Output Impedance | 10K (Monograph and Panorama)
15K (Monograph Premium, Panorama Premium, and Silvermine) |
| Recommended Amplifier Input Impedance | 100K Ohms |
| Total Harmonic Distortion | No more than 0.1% |
| IM Distortion | No more than 0.1% |
| Signal-to-Noise Ratio | Better than 87dB |
| Phase | Non-Inverting |
| External Ground Connector | Earth Ground (AC Earth) |
| Signal Ground | Switchable via locking rear toggle:- Signal Grounded or
- Floating
|
| Dimensions | 17.48" Wide x 16.0" Deep x 4.0" High (including feet)
(444mm Wide x 406mm Deep x 101mm High) |
| Net Weight | 12 lbs. (5.44 kg) |
| Shipping Weight | 20 lbs. (9.1 kg) |
| Panorama, Panorama Premium, and Silvermine Audio Stages |
| Gain | +60dB Moving Coil Phono
+40dB Moving Magnet Phono
+14dB Active Line
0dB Passive Lines |
| Tube Complement (Vintage NOS USA or UK tubes supplied) |
| 1st Gain Stage | Raytheon 5842 (Panorama) or Western Electric 417A (Panorama Premium and Silvermine) |
| 2nd Gain Stage | RCA 6GK5 / 6FQ5A |
| 3rd Gain Stage | Tung Sol 5687 x 2 |
| 3rd Gain Stage | Tung Sol 5687 Active Line |
Inputs
| Phono x 3 (up to 6 possible)
Passive Line x 2
Active Line |
| Outputs | Main Out x 2 in Series
Record Out x 1 |
| EQ Filters | Treble (12-position "Roll-Off")
Bass (12-position "Turnover")
Deep Bass ("Shelf" fixed at 50Hz) |
| Frequency Response | 5Hz - 50KHz |
| Phono Input Impedance | 12 built-in selectable values, plus the option of a 12th custom value via an internal, spring-loaded socket. |
| Phono Output Impedance | 10K Ohms (typical) |
| Recommended Amplifier Input Impedance | 100K Ohms (typical) |
| Total Harmonic Distortion | No more than 0.1% |
| IM Distortion | No more than 0.1% |
| Signal-to-Noise Ratio | Better than 87dB |
| Phase | Non-Inverting |
| External Ground Connector | Earth Ground (AC Earth) |
| Signal Ground | Switchable via locking rear toggle:- Signal Grounded or
- Floating
|
| Dimensions | 17.48" Wide x 16.0" Deep x 6.5" High (including feet)
(444mm Wide x 406mm Deep x 165mm High) |
| Net Weight | 13 lbs. (5.9 kg) |
| Shipping Weight | 21 lbs. (9.5 kg) |
| Panorama Silvermine Preamplifier |
| | Replace the three copper foil coupling capacitors with Jupiter, Audio Note, plus three Duelund Silver Hybrid coupling capacitors and six critically placed Audio Note Silver/Tantalum resistors. |
| Monograph Power Supply (Monograph Preamp) |
| Tube Complement | 6C4 / EZ81 Rectifier (Vintage NOS RCA or Mullard supplied) |
| AC Mains Input | Nominal 120V @ 60Hz.
On request, the 1201B+ power supply can be supplied for 240V / 50Hz at no extra cost. Other worldwide voltages are available. |
| Dimensions | 8.37" Wide x 16.0" Deep x 3.47" High (including feet)
(213mm Wide x 406mm Deep x 88mm High) |
| Net Weight | 14 lbs. (6.35 kg) |
| Shipping Weight | 20 lbs. (9.1 kg) |
| 1201B+ Power Supply (Monograph Premium, Panorama Premium, and Panorama Silvermine Models) |
Tube Complement
(Vintage NOS USA or UK tubes supplied) | 5V4 Rectifier
6FW5 Output
6AN8A Amplifier
12AT7 Amplifier
5651 Regulator |
| AC Mains Input | Nominal 120V @ 60Hz.
On request, the 1201B+ power supply can be supplied for 240V / 50Hz at no extra cost. Other worldwide voltages may be available. |
| Dimensions | 8.37" Wide x 16.0" Deep x 6.25" High (including feet)
(213mm Wide x 406mm Deep x 160mm High) |
| Net Weight | 23 lbs. (10.4 kg) |
| Shipping Weight | 31 lbs. (14 kg) |
Prices in USD $
Plus shipping from Troy, New York 12180, USA |
Monograph
Fabricated with high quality parts, including the separate Monograph Power Supply | $3,900 |
Monograph Premium
Fully upgraded with premium parts, including the separate 1201B+ Power Supply | $6,900 |
| "Naked" Vishay TX2575 Custom Phono Load Resistors | $25 each |
Panorama
Fabricated with high quality parts, including the separate Monograph Power Supply | $5,900 |
| Additional phono inputs or main outputs based on Kimber Ultra-Plate sockets | $50 each |
| Additional "Naked" Vishay TX2575 Custom Phono Load Resistors | $25 each |
| WE417A 1st Stage Tube | $250 each, selected for low noise and microphonics |
Panorama Premium
Fully upgraded with premium parts, including the separate 1201B+ Power Supply | $7,900 |
| Additional phono inputs or main outputs based on WBT NextGen Ag Pure Silver sockets | $100 each |
| Additional "Naked" Vishay TX2575 Custom Phono Load Resistors | $25 each |
| Additional phono inputs or main outputs based on WBT NextGen Ag Pure Silver sockets | $100 each |
| Panorama Silvermine | $9,995 |
| Upgrade the Panorama Premium with Jupiter and Audio Note Silver Foil coupling capacitors, plus three Duelund Silver Hybrid coupling capacitors and six critically placed Audio Note Silver/Tantalum resistors. | |
| Stereo Playback | Two complete mono units, including two mono power supplies, are required for stereo |
| Warranty | 10 years, transferable, on parts and labor. 90 days on vacuum tubes. Unauthorized parts substitution or modification(s) may void the warranty. |
| Availability | First Quarter of 2024 |
Conceptual illustrations, specifications, prices, and production dates are subject to change without notice.
Tempo Electric Custom Audio LLC
PO Box 770
Saratoga Springs, NY 12866-0770
USA
+01 (518) 542-7004
The best time to reach us by telephone is 10AM-7PM, US Eastern Time.
If you reach our voicemail, please leave a message or send an eMail to  .
Either way, we will try to reply within 24 hours.
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