The Monograph Mono Preamplifiers have been discontinued. This page has been left for future reference. |
Monograph Mono Preamplifier, Front Panel
Monograph Mono Preamplifier, Rear View
|
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. In addition, in the world of 78s, there is also a low bass setting called "Shelf" which is fixed at 50Hz.
The audio circuit, designed by Dr. Arthur Loesch (pronounced "Lesh," like the Grateful Dead's Phil Lesh), is virtually identical to 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. The primary difference is the addition of variable bass (Turnover) and treble (Roll-Off) filters, for which Dr. Loesch calculated the values, as well as a new low output circuit for high output cartridges. With 12 bass and 12 treble restoration points, a total of 144 different equalization curves (including RIAA) are possible. With the right combination dialed in, vocals and instruments are fully restored to their proper balance.
| Bass Turnover Switch Position | Bass Turnover Time Constant | | Treble
Roll-Off Switch Position | Treble
Roll-Off Attenuation @ 10kHz |
|---|
| A | Acoustic | 1 | 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 a future listening session. For example, a record cut with the RIAA curve can be labeled "J 11," Okeh 78s can be labeled "D 4," early Blue Notes "J 7," and so on.
A comprehensive guide to 78 RPM 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 MonographTM single channel, 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 requirement for a high-end, dedicated monaural phono system.
Features in the Monograph 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)
- Two separate mono phono inputs, selectable from the front panel
- 100 ohm and 47K ohm phono load resistors, switchable from the front panel
- Provision for a custom phono load resistor in any value
- 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
- An Alps volume control
- Double-thick, 0.125" circuit boards with extra heavy traces for low internal resistance
- High quality audio capacitors by Audyn, Mundorf, ASC, MIAL (Philips), and Solen
- High quality audio resistors by Vishay, Caddock, Huntington, Takman, KOA, Dale, Holco, and Roderstein
- Classic-style, full-size components throughout; no sub-miniature SMDs (Surface Mount Devices)
- No electrolytic capacitors in the Audio Stage
- Pure silver, Teflon-insulated audio signal wire
- Teflon-insulated, silver-plated copper wire throughout the power supply
- 120V/60Hz and 240V/50Hz user switchable voltages for world-wide use
- 15A Furutech Male IEC connector on the power supply for use with custom and worldwide power cords
- Assembly by hand in our workshop in Troy, NY, with 95% of the parts sourced from USA and European manufacturers
Monograph Power Supply (Concept)
|
The upgraded Monograph Premium model include these additional features:
- A Western Electric 417A First Stage tube, specially selected for low noise and low microphonics
- Premium copper foil audio capacitors by V-Cap, REL AudioCap, and Jupiter
- Premium audio resistors including "Naked" Vishay TX2575, Audio Note Tantalum, Caddock, Huntington, Dale, and PRP
- 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: 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) |
| 2nd Gain Stage | RCA 6GK5 / 6FQ5A |
| 3rd Gain Stage | Tung Sol 5687 x 2 |
Inputs:
| Phono x 2 |
| Outputs | Main Out x 2 Connected 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 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) |
| Monograph Power Supply (Monograph Preamp) |
| Tube Complement | 6C4 / EZ81 Rectifier (Vintage NOS RCA or Mullard supplied) |
AC Mains Input
(Dual Voltage on a toggle switch) | 120V / 60Hz
240V / 50Hz |
| 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) |
Tube Complement
(Vintage NOS USA or UK tubes supplied) | 5V4 Rectifier
6FW5 Output
6AN8A Amplifier
12AT7 Amplifier
5651 Regulator |
AC Mains Input
(Dual Voltage on a toggle switch) | 120V / 60Hz
240V / 50Hz |
| 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 | $3,895 |
Monograph Premium
Fully upgraded with premium parts, including the separate 1201B+ Power Supply | $6,895 |
| "Naked" Vishay TX2575 Custom Phono Load Resistors | $25 each |
| Additional phono inputs or 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 |
| 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 | Discontinued |
The Monograph Mono Preamplifiers have been discontinued. This page has been left for future reference. |
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 1PM - 6PM, 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.
|
HOME
ABOUT US
PRODUCTS
eMAIL LIST
PURCHASE
