Genesis M60 power amp

 

The Genesis Monoblock 60-Watt Valve (or vacuum tube) Amplifier is a limited-edition product that was created as proof of concept that a well-designed, well-executed, value-priced amplifier will be able to drive any Genesis loudspeaker with ease and authority. The transparency, detail retrieval, dynamics, and wide frequency extension of Genesis loudspeakers place great demands on the quality of amplification. Because of our emphasis on absolute fidelity™ above all else, the speakers do represent a difficult, but not impossible load for an amplifier to drive.
The M60 was created as a partner to a pair of Genesis loudspeakers, and as a result, it has the quality of amplifiers costing much more. The M60, together with a pair of Genesis loudspeakers, will give your entire music collection a whole new life. In a well set-up system, it is capable of transporting the musical performance into your room. The hiss and hum normally associated with vacuum tubes are completely absent, while retaining the richness and rightness of the best of this genre of amplifiers.

While developing a value-priced product, quality has not been scaled down. Hand-selected, precisely matched components are used throughout: custom-made military-spec paper-in-oil capacitors with aluminum cans are selectively used; the output transformers and power transformer are laboriously hand wound to precise specifications tailored to the circuit and valves used. Point-to-point wiring using solid-core silver wire is used in the entire signal path. This reduces the resistance, capacitance and inductance normally associated with ordinary printed circuit boards. Each and every unit is first burned-in on the test bench, and then run in for over 100 hours before final test and packaging.

Very little feedback is used – just enough to make the amplifier unconditionally stable. Not the excessive amount usually employed to make amplifiers measure better at the expense of musicality. The result of all this obsessive attention to detail is a fabulously musical power amplifier capable of driving almost any loudspeaker in the world.

Before using this unit, please take the time to carefully review the safety instructions and operating information contained in this Owner’s Manual and Set-up Guide. Becoming familiar with your new amplifier and the correct operating procedures will help assure you of safe usage, reliable operation, and maximum musical enjoyment.

 

About M60 Amplifier

The Genesis Monoblock 60-Watt Valve Amplifier uses proprietary circuits, high quality components, and state-of-the-art vacuum tube topology to deliver sonic performance rivaling other amplifiers costing much more. The design objectives of this product are to: 1.  Deliver musically accurate amplification, 2.  Provide a vacuum tube amplifier that would approach the reliability and ease of use of solid state amplifiers, and 3.  Provide an affordable vacuum tube amplifier that would be able to drive the Genesis family of loudspeakers. A valve amplifier matched with an appropriate loudspeaker can produce a sound that we can only call magic. The hard, brittle, and edgy presentation of many transistor amplifiers is contrasted with the rich, lush and silky sound of the tube amplifier. Often, valve amplifiers offer much better imaging and sound stage presentation compared to an equivalently priced solid-state amplifier. It is more musical, and the performance seems almost alive.

A properly designed and built valve amplifier, such as the Genesis M60, is capable of reproducing midrange and treble with crystal clear definition – the sound can only be described as smooth and silky, and musically accurate with the right timbre and harmonics.  As for the bass, the M60 is designed to maintain tight control over the bass, and deliver the powerful punch and dynamics at the low end with the solidity and weight of transistor amplifiers. 

Design and Construction

The Genesis M60 uses a single 6SL7 as an input stage in the standard mu-follower configuration with 6SN7’s in the driver stage. No ordinary 6SN7’s for the M60 though – military spec 6N8P are selected for their reliability and durability, and then hand-picked for linearity and low noise. A matched-pair of KT88 power output valves are used to deliver a very conservative 60 watts. While the M60 is developed as a value-priced product, quality has not been scaled down. Extensive listening tests were done throughout the design process, and expensive components were used where they were appropriate. Custom-made military-spec paper-in-oil capacitors with aluminum cans are selectively used and low-noise gold plated military-spec ceramic tube sockets are used throughout.

Very little feedback is used – just enough to make the amplifier unconditionally stable. Not the excessive amount usually employed to make amplifiers measure better at the expense of musicality.

During construction, all components are hand-selected and precisely matched. The output transformers and power transformer are laboriously hand wound to precise specifications tailored to the circuit and valves used.  Point-to-point wiring using solid-core silver wire is used in the entire signal path. This reduces the resistance, capacitance and inductance normally associated with ordinary printed circuit boards.

The only PCBs you see in the “guts” of the amplifier are the boards associated with biasing of the power tubes, and the soft-start electronics. The output transformers are custom designed and hand-wound with a core of grain-oriented silicon steel specifically for the output tubes used. Two output taps are provided on the secondary – 4ohm and 8ohm – with the 4 Ohm tap specifically tuned using Genesis loudspeakers. Each amplifier is extensively inspected and tested at every stage of manufacturing. It is also allowed to burn-in before the valves are biased and calibrated, and then run-in for 100 hours before finally being electronically tested prior to packing for shipment. Hence, it should come to you ready to use straight out of the box

Specifications

Rated Power Output:   60 W RMS

Frequency Response:  20 Hz - 30 kHz,   (<1% T.H.D)

Input Impedance:  250 k Ω

Output Impedance:  4 Ω  or 8 Ω  

Signal to Noise Ratio:  >90 dB

Vacuum Tubes:  KT88 x 2;  6N8P x 2 (or 6SN7 may be used); 6SL7 x 1 (or 5691 may be used)

Dimensions (W x H x D):  480 x 185 x 380 mm (17" x 7 ¼” x 15”)

Weight:  17 kg (38 lbs)

Adcom GFA-565 power amp

Adcom stereo components have a loyal and devoted following, having earned a reputation among audiophiles, engineers and musicians for extraordinary performance at affordable prices. Now Adcom introduces its newest amplifier, the no compromise GFA-565, for those in pursuit of absolute power and sonic perfection, but who prefer not paying a king;s ransom.

The evolution od Adcom's GFA-565

Adcom's new mono GFA-565 evolves from the design of the critically acclaimed GFA-555, greatly extending its capabilities. Representing brute strength, it delivers 300 watts at 8 ohms, 450 watts at 4 ohms and an awesome 850 watts at 2 ohms. most significantly, it will accurately drive even esoteric loudspeakers which present loads as low as 1 ohm.

Inspired by the GFA-555, the new GFA-565's well-regulated, high-current power supply has an enormous reserve capacity to meet tremendous dynamic demands, resulting in distortion free reproduction on a continuous basis.

Why use Two Mono Amplifiers?

The ability to deliver very high power into complex loads is a prereguisite for superior sound reproduction. power supplies capable of delivering the energy necessary for high power, high-current amplifiers are massive. but there are prectical limits to the size and weight of stereo amplifiers designed for home use, as well as heat dissipation and reliability constraints. consequently, the use of two Adcom GFA-565 mono amplifiers offers optimum sound definition, detail and dynamics, satisfying even the most demanding perfectionist.

More Sound. Less Money

Like the GFA-555, the new Adcom GFA-565 sound superior to amplifiers costing two and three times as much. it is so powerful and pure that it may be the last amplifier you ever buy, even if you upgrade your loudspeakers several times over the years. And that makes the GFA-565 an extraordinary bargain considering its exceptional performance.

 

High-Current Output Stage

More and more of today's high performance loudspeakers exhibit very low impedances and particularly difficult loads. many so-called esoteric amplifiers are incapable of delivering large amounts of undistorted power continuously into these complex loads thereby defeating the objectives of the loudspeaker's design. The GFA-565's highly advanced, triple darlington output stage featuring 20 rugged, discrete output transitors is designed to deliver extremely high-current at low impedances and reactive loads. No protection circuitry or current limiting devices are incorporated which would restrict the delivery of full power output. Protection against short term overloads, short circuits or long term, excessive output is achieved by non-interfering power supply fuses and thermal circuit breakers.

 

Well regulated, High-Current Power Supply

Advancements in CD technology and the introduction of digital audio tape have created opprtunities to reproduce the full dynamics and psychoacoustic experience of a live musical performance. To realize the full potential of this technology, amplifiers and loudspeakers must be capable of delivering tremendous energy continuously, not just for tiny fractions of a second. The massive power supply of GFA-565, featuring 70,000 microfarads of filter capacitance and a huge 1,25 kVA toroidal power transformer, has enormous reserve power capability. this is a no compromise power supply that eliminates all audible limitations. Hum, vibration and noise, the byproducts of lasser power supplies, have also been reduced to an absolute minimum. For most home applications, the optional variable speed cooling fan is unnecessary, making the GFA-565 a silent performer despite its formidable power.

Instananeous Distortion Alert

A highly accurate LED on the front panel is activated by a unique monitor circuit if any form of distortion - THD, IM, TIM, SID, etc. - exceeds 1 percent. this will provide ample warning that the music system is being operated beyond its design parameters.

Specifications:

Continuous Power Output (20 Hz - 20 kHz, less than 0,02% THD)

300 watts/channel at 8 Ω

450 watts/channel at 4 Ω

850 watts/channel at 2 Ω

Signal-to-Noise  Ratio:  better than 106 dB (A-weighted, full output)

Input Impedance:  50 - 700 Ω

Input Sensitivity:

For Rated Output :  2,15 V

For 1 Watt :  130 mV

Damping Factor:  better than 1000 at 8 Ω  (20 Hz - 20 kHz)

Dynamic Headroom (at 4 Ω):  1,6 dB

Voltage:  120 V, 60 Hz (availaable in 220 V, 50 Hz on special order)

Dimensions (W x H x D) :  432 x 210 x 292 mm (17" x 8-1/4" x 11-1/2")

Weight (shipping):  20,5 kg (45 lbs)

Optional:

Top mounted, automatically variable, ventilating fan (565 FAN)

Rear mounted, symmetrical balanced line input circuit (565 BAL)

Rack mount adaptors (RM-8)

White front panel and switch

McIntosh MC-60

The Mcintosh Model MC-60 is a 60 watt high fidelity power amplifier designed for home entertainment systems and professional applications where high power and distortion free performance is required. The Model MC-60, like all other McIntosh power amplifiers. Uses the exclusive McIntosh high efficiency output circuit and bifilar output transformer to obtain the high standard of performance found in this amplifier.

Some of the more important characteristics of the amplifier are less than 1/3% harmonic distortion at any power output up to 60 watts and at any frequency in the audio spectrum, 20 to 20,000 cps; less than 1/2% intermodulation distortion for all power levels up to 120 instantaneous peak watts; and noise and hum level 90 dB or more below the rated output level.

The MC-60 has two high impedance inputs and many be operated from any signal source deliviring 0,5 volts or more, or directly from a McIntosh Audio Compensator or pre-Amplifier such as the  Models C-4, C-8, C-104 or C-108.

Output impedances of 4, 8 and 16 ohms are provided for direct connection to loudsapeakers. An additional 600 Ω output is present for use with lines.

Specifications

Power Output:  60 watts continuous

Input Level:

Input 1 :  0,5 volts to 30 volts, with gain control

Input 2 :  2,5 volts (for use with McIntosh Audio Compensators and pre-Amp)

Frequency Range: 

20 to 30,000 Hz ±0,1 dB at 60 watts output

16 to 60,000 Hz ±0,5 dB at 60 watts output

10 to 1000,000 Hz ±1,0 dB at 30 watts output

Total Harmonic Distortion:  less than 1/3% at 60 watts output or less, 20 to 20,000 Hz

Intermodulation Distortion:  less than 1.2% if instentaneous peak power is below 120 watts

Impulse Distortion:  Negligible

Noise and Hum level:  90 dB or more below rated output

Damping Factor:  15 or better for 4, 8 and 16 Ω output, 20 for 600 Ω

Input Impedance:

0,5 meg for 0,5 volt input

0,13 meg for 2,5 volt input

20 cycles to 40,000 cycles

Output Impedance:

4, 8, 16 and 600 ohms (600 ohmis balanced to ground)

Phase Shift:  ±8° 20- 20,000 Hz

Tube Complement:

Rectifier :  2-5U4GA

Pre-Amp :  12 AX7

Phase Inverter : 12AU7

Voltage Amp : 12BH7

Driver : 12AX7

Output : 2-6550

Dimensions (W x H x D):  14" x 10" x 8"

Weight:  41 pounds net

Finish :  chrome and black

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McIntosh MC 3500

The McIntosh MC 3500 sets a new precedent in high power performance and flexibility.

Many years of diligent research, space age product advances and careful examinations  of new developments in component parts have lead to the McIntosh MC 3500, a new Laboratory Standard.

The quality performance that is demanded in the scientific laboratory  is your for the highest performance in a home music system.

McIntosh  developed the first low distortion, high quality, high powered amplifier in 1947. the secret then was the Unity Coupled circuit and Bifilar Output Transformer.

The MC 3500 has made another new advance. Again transformer design has made the difference. A new output transformer with 5 primary windings, interleaved with the secondary to give you maximum output, lowest distortion, multiple output impedance for any type type of sound distribution requirement. The new McIntosh Pentafilar output transformer and Unity Coupled circuit means lowest distortion, flat power response, long, trouble free cooler operation at high power.

McIntosh has produced the answer to the majority of sound problems. With the McIntosh MC 3500, your music system will produce music as never before. All the instruments will be reproduced with clarity and accuracy. No more will you hear just a barrage of sound. Now you will hear each instrument clearly and cleanly without the cloudiness produced by the lack of power in the amplifier. The McIntosh MC 3500 is the ultimate in high power amplifiers.

Specifications

Power Output:  350 RMS watts continuous

Harmonic Distortion:  0,15% at 350 watts power output from 20 Hz to 20 kHz. Typical performance is less than 0,1% at rated power. Distortion decreases as output power is reduced.

Frequency Response:  20 Hz - 20,000 Hz (+0 -0,1 dB at rated output); 7 Hz - 70,000 Hz (+0 -3,0 dB at 1 watt)

Noise and Hum:  95 dB below rated output

Output Impedance and Voltage:  1 Ω/ 17,3 V; 4 Ω/35,8 V; 8 Ω/53 V; 16 Ω/75 V; 50 Ω/132V; 64 Ω/150 V. may be operated isolated from ground. (1 Ω/17,3 V output is rated to 300 watts, and 4 Ω/35,8 V output is rated to 320 watts)

The 75 Volt output is used to power 70,7 V sound distribution lines. The 150 V output is used to power 141,4 V distribution Lines. The 132 Volt output is used to provide 117 V for laboratory or industrial applications.

Internal Impedance:  about 5% of rated load Impedance. The 1 Ω/17,3 V output is rated about . 1 Ω

Input Impedance:  200,000 Ω

Input Sensitivity:  1,1 volts. Level control provided for higher input voltages.

Power Requirement:  117 volts AC 50/60 Hz, 400 watts at zero signal output:  900 watts at rated output.

Solid State Complement:  3 Silicon Transistors; 2 Silicon Zener Diodes; 3 Germanium Diodes; 9 Silicon Retifiers and Diodes

Tube Complement:  2 x 12AX7; 2 x 6DJ8; 1 x 6CG7; 1 x 6BL7; 8 x 6LO6

General

Dimensions:

Front panel :  10-1/2" (high), 19" (wide)

Chassis :  17" behind panel including connections

Knobs project 2" in front of panel.

Finish:

Front panel :  Gold anodized aluminum and black

Chassis :  Chrome and black

Weight (Chassis only):  125 pounds (shipping 135 pounds)

I like 

Mark Levinson ML-2

ML-2 Monophonic Power Amplifier

ML-2 Class A power Amplifier in the appropriate system will produce striking sonic results. Each musical instrument is more articulated, while clear and open sound is maintained. Harshness seems to disappear from instruments with higher frequency content, such as violins. Music takes on more body and fullness. Absolute solidity of deep bass gives the entire performance an essential foundation and enables the listener to hear notes and passages that were previously inaudible. With quality recordings, the image of a performance is precise and remarkably stable appearing to emanate from a wider, taller and deeper stage.

The ML-2 may be operated in either the inverting or non-inverting mode. This allows a pair to be used in bridged configuration without additional circuitry. In bridged mode, two Ml-2s deliver twice the output voltage and four times the power. The power supply is fully regulated under all operating conditions. The ML-2 offers completely modular construction allowing efficient up-dating 9when available) and ease of servicing if required.

While outstanding performance can be achieved in high power amplifier designgs, the refined sound quality offered by ML-2s can only be attained by a design that, by today's standards, is limited in output voltage. The ML-2 is rated at 25 watts continuous sine wave power into 8 ohms from 20 Hz to 20 kHz with no more than 1% THD. For this reason, Ml-2s work best with higher efficiency loudspeakers, in multi-amp systems, or with lower efficiency speakers where loud listening levels are not required. While Ml-2s may not be optimum for every application, in the appropriate system they offer a beauty of musical sound unachievable by any other design.

Specifications ML-2:

Rated Power:  25 watts minimum continuous sine-wave power into 8 Ω from 20 Hz - 20 kHz with no more than 1% THD.  

Input Impedance:  100,000 Ω

Power Supply:  AC 100, 120, 220, 240 Volts, 50/60 Hz

Power Requirement:  400 Watts nominal, 50 - 400 Hz

Connector Complement:  2 Camac coaxial connectors; 13-pin audio connector (XLR); 5 binding posts; 1 AC receptacle/line voltage selector

Dimensions (overall W x H x D):  483 x 216 x 546 mm (19" x 8,5" x 21,5")

Weight:  29,6 kg ( 65 pounds)

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B&W MPA-1

 The B&W MPA-1 is a high quality 120 watt, into 8 ohms load, monoblock amplifier. Its design is directly derived from the Mos-FET power modules employed in the MPA-810 professional studio amplifier.

This unique amplifier is the first in a series of electronic products which incorporate the highest engineering technology within a set of sophisticated designs developed specifically for use in the home. In line with established B&W tradition, the new products are designed and produced entirely in-house.

System topology and component specification are in keeping with the latest knowledge of how sonic realism is best achieved. For those who like to deploy the more exotic system configurations, MPA-1 is equipped with dual outputs, to facilitate bi-wiring - and with ATO (audio turn-on) to simplify the remote siting of power amplifiers. Some professional and audiophile systems call for long input wiring runs, frequently necessitating the use of balanced line feeds. Consequently, MPA-1 is equipped with a balanced XLR input in addition to the more common single-ended phono connection.

 B&W MPA-1 contains three circuit boards; input buffer, power amplifier and power supply.

The input buffer is a low noise, unity gain differential amplifier which converts balanced inputs to single-ended signals which can then be fed to the main amplifier stage. In addition, this board contains the signal detection circuitry for ATO, the main power switching control and both current and offset protection. This circuitry is supplied by a small. Regulated standby supply, which remains active as long as the mains power is connected.

The main amplifier consists of a dual complementary differential input stage feeding high linearity cascode drivers to give voltage gain. Finally, two matched pairs of complementary power Mos-Fets are incorporated as current buffers. Separate supply connections are made to the output stage, permitting independent supply regulation for the input and driver stages.

The heart of the power supply is a custom-designed 300 VA transformer with two low-impedance, 10,000 µF capacitors providing the main charge storage elements for the output stage. An additional pair of capacitors with regulators supplies the higher voltage requirements of driver and input sections. Mains power control is achieved with an opto-isolated solid state switch, allowing operation for the low level output of the power control logic circuitry.

Specifications

Power Output (Continuous 20 Hz - 20 kHz):

120 W into 8 Ω

200 W into 4 Ω

Current Limit:  ±16 A

Output Impedance:  1 m Ω (measured at main PCB)

Input Impedance:  24 k Ω

Voltage Gain:  29,2 dB

THD:  0,03%

IM Distortion:  0,03%

Frequency Response:  10 Hz - 20 kHz, +0 dB -0,4 dB (input filter limited)

Distortion (A-weight):  better than -86 dB (20 Hz -20 kHz at 5 W / 8 Ω)

Signal-to-Noise Ratio (A-weight):  -100 dB

AC Voltage Requirements:  110/130/150/220/240/260 V AC

Power Consumption: 

Standby: 1,2 VA (at 240 V)

Idling: 40 VA

Full Output: 4 Ω - 500 VA

Dimensions (H x W x D):  167 x 175 x 200 mm

Weight:  7,5 kg

Marantz Model 5

 The Power Amplifier Model 5 it is  a revised and more attractive version of the Model 2

Marantz Power Amplifier have been designed and constructed to give a long, trouble-free life of fine listening quality. Here is the type of performance and workmanship that previously was found only in high quality broadcast or laboratory equipment. Built-in metered test instruments permit simple, accurate adjustments for optimum performance.

 The Model 5  is essentially a smaller version of the 40 Watt Model 2, with certain minor simplifications, never theless embodying fully the same quality.

Its exterior design adapts itself to instalation requirements for multiple amplifier systems such as in stereophonic applications and in those embodying the Marantz Electronic Crossover.

Specifications

Power Output:  30 Watts (60 Watts peak) "Ultra-Linear" operation.

18 Watts of excellent Triode operation can be had by altering two connections inside chassis.

Output Connections:  4, 8 and 16 ohms

Input Sensitivity (for 30 watts):  1,3 volts RMS into 250 kohm

Response:

At 30 Watts : Within 0,2 dB from 20 cps to 20 kc 9equivalent of ±0,1 dB from 15 cps to 40 kc into "Grid" (or test) input.

At ½ Watt : ±1 dB from 3 cps to 40 kc. Response has been deliberately rolled off approx. 7 dB at 100 kc to control transient response.

Subsonic Filter in standard "Input" slowly rolls response off below 20 cps (less than 1 dB at 20 cps, -10 dB at 3 cps, etc)

Distortion at 30 Watts

Total Harmonic Distortion :  less than 0,1% at mid-frequencies. Less than 0,5% from 20 cps to 10 kc. Less than 1,0% at 20 kc with resistive load (much less of equivalent voltages with inductive speaker loads).

Intermodulation Distortion :  less than 0,5% (60 cps/12 kc, 4:1)

IM measurement of typical amplifier: 35 W equivalent  0,5%;  30 W equiv.  0,28%;  20 W equiv.  0,17%; 10 W equiv.  0,11%

Distortion below 30 W is largely of 2nd order and reduces rapidly with signal level

Damping Factors:

Greater than 20 from 20 cps to 20 kc (instructions given for optional insertion by the customer of two additional resistors to provide damping factors of 2, 1, or ½)

Inverse Feedback and Stability:

20 dB of overall feedback. Great care has been taken to ensure stability and low distortion under widely varying loods, both resistive and reactive, such as are encountered in loudspeaker systems.  Power supply surges are balanced out of signal channels providing excellent recovery from strong transients. Will not oscillate under any condition of open circuit capocitive load.

Hum:

Beter than 90 dB below 30 Watts containing proportion ately little of high order components.

Metered test and Adjustments:

Built-in meter and test switch provide acurate adjustment of each output tube bias. This makes the use of matched tubes unnecessary. Adjustable A.C.  Balance (located subchassis) pre-set at factory

Power Supply:

The use of a transmitting type oil condenser, choke, telephone quality electrolytic, and GZ-34 heater-cathode rectifier provide protection from starting surge voltages, improved regulation, and thorough filtering, together with long life.

Power Requirements:

Design center 117 volts, 60 cycles. Range 105 -125 volts. 100 watts at zero signal; 130 Watts at maximum signal

Tube Complements:

1 x 6BH6;  1 X 6CG7;  2 X EL34/6CA7;  1 X GZ34

Dimensions (W x H x D):  6" x 7 ⅜" x 15 ¼"

Weight:  35 lbs (shipping with grille)

Marantz Model 2

 The Marantz Power  Amplifier has been designed and constructed to give a long, trouble-free life of line listening quality. Here is the type of performance and workmanship that previously was found only in high quality Broadcast or Laboratory equipment. A built-in metered test instrument permits simple, accurate adjustments for optimum performance.

 "The Model 2 power amplifier followed in 1956. largely completed by Sidney Smith, it was a very successful tube design using EL34's in ''ultra-linear'' (push-pull) configuration.

… some sources cite the Model 2 as the beginning of Smith's exclusive concentration on power amplifiers while Saul focoused his attention on preamplifiers,…" (from Marantz History)

 40 Watt / 20 Watt Switch

This unit has been designed primarily as a 40 watt ultralinear amplifier. Speaker systems of a lower power rating could easily be damaged by unwanted pulses coming through at full power. To protect these systems we have incorporated a switch which changes the output connections to Triode operation limiting the power output to 22 or 23 Watts. This control, located near the output terminal strip, is marked '40 Watt UL' and '20 Watt TRI'.

 Input Connections

There is a choice of three input connections to the Marantz Power amplifier.

Pre-Amp: This input is recommended for most preamplifiers. At this connection a 2 volt signal will drive the amplifier to it's full output. A subsonic filter rolls off frequencies below 20 cycles so as to supress speaker "breathing" and other subsonic disturbances.

High Gain, Filtered: For preamplifiers that have a low output voltage capability. Also may be used where loudspeaker has very low efficiency. A signal of 0,7 volts is required here for full 40 watt output. Subsonic filtering is also in effect.

High Gain, Unfiltred: Same as above in sensitivity but without the subsonic filter, response being maintained to below 2 cycles. This input is direct to the input grid and is used in testing frequency response or for special applications where subsonic response is needed.

 Output Connections

When not using Variable Damping:

Use "Ground Return" (center terminal) on loud speaker output terminal strip together with impedance tap on right which matches speaker.

Variable Damping control must be switched off for proper operation.

To use Variable Damping:

Instead of usual ground return, connect to corresponding "Variable Damping Return".

Turn "variable Damping" control on and adjust to desired damping factor.

Specifications

Power Output:  40 Watts ( 80 Watts peak). "Ultra-Linear" operation.

20 Watt Triode Operation. Switch changes output connections to protect speaker of low-power rating.

Output Connections:  4, 8 and 16 Ω from Ground Return. 4, 8 and 16 Ω Variable Damping returns.

Input Sensitivity for 40 Watts:

Two High Gains Inputs:  0,7 V RMS into 105 k Ω

Pream Input: 2 V RMS into 285 k Ω

Response (has been deliberately rolled off approx. 5 dB at 100 kHz to control transient response):

At 40 Watts : Within 0,1 dB from 20 Hz - 20 kHz, within  1 dB from 15 Hz - 45 kHz

At ½ Watt : ±1 dB from 2 Hz - 50 kHz

Subsonic Filter: In Preamp and High-Gain Filtered inputs, response is slowly rolled off below 20 Hz (less than 1 dB at 20 Hz, 10 dB at 3 Hz; etc)

Distortion

Total Harmonic Distortion at 40 Watts: 

less than 0,1% at mid-frequencies;

less than 0,5% from 20 Hz to 10 kHz;

less than 1,5% at 20 kHz with resistive load  (for less at equivalent voltages with inductive speaker loads)

Intermodulation Distortion at 40 Watts (equvalent 80 watt peak):  Less than 0,5% (60 Hz /12 kHz  4:1

Distortion below 30 Watts is largely of 2ad order and reduces rapidly with signal level.

Damping Factors

Greater than 20 from 20 Hz to 20 kHz (without Variable Damping connections)

Continuously Variable from 5 to ½ with Variable Damping connections

Inverse Feedback and Stability

23 ½ dB of overall feddback (20 dB in triode position). Great care has been taken to ensure stability and low distortion under widely varying loads, both resistive and reactive, such as are encountered in loudspeaker systems. Power supply surges are balanced out of signal channels providing excellent recovery from strong transients. Will not oscillate under any condition of open circuit capactive load.

Hum

Better than 90 dB below 40 Watts (containing proportionately little of high order components)

Meterd Tests and Adjustments

Bias, D.C. Balance, A.C. Balance (drive).All accurately adjustable with built-in D'Arsonval meter and test switch

Power Supply

The use of a transmitting-type oil input condenser, choke, telephone quality electrolytic and the new type 6AU4-GTA as heater-cathode rectifiers provide, protection from starting surge voltages, improved regulation and thorough filtering

Power Requirements

Design center; 117 volts, 60 Hz. Range 105 -125 volts. 150 Watts at Zero signal, 200 Watts at maximum signal

Tube Complement

1 x 12AX7 / ECC83

1 X 6CG7

2 X 6CA7 / EL34

2 X 6AU4GTA

Size and Shipping Weight:  15" x 9½" x 6½" / 47 lbs

Marantz Model 14 (Fourteen)

 The Marantz Model 14 is the Single Channel Amplifier

If you need a high-quality amplifier for monophonic or  center-channel operation, then the Model 14 is the ideal choice. Available in utility form, it has the same performance specifications and circuitry of each channel of the Model 15.

Specifications

Power Output Each Channel:  

70 Watts at 4 ohms

60 watts at 8 ohms

40 watts at 16 ohms

Frequency Response:  Within 1 dB,  10 to 60,000 Hz

Damping Factor:  Greater than 30 with 8 Ω load.

Total Harmonic Distortion:  less than 0,1% at and below rated power, 20 to 20,000 Hz

Typical Harmonic Distortion:  0,03% with 8Ω or higher load - at full rated output,any frequency from 20 to 20,000 Hz. Distortion decreases as output level is lowered.

Total Noise:  better than 90 dB below 60 watts into 8 ohms.

Power Requirenets:  105 - 130 V AC, for 50-60 Hz. Easily covertible form 110 volt to 220 volt operations.

McIntosh MC-30

McIntosh, the world's most advanced amplifier is unequalled for quality reproduction of any sound source. Its unique circuitry provides ample reserve power combined with unprecedented low distortion - less than 0,5% harmonic distortion at all frequencies, 20-20,000 Hz (cycles) and at any volume, even full power. Designed for those who expect the finest, the McIntosh MC-30 sets a new standard among amplifiers today. It Brings an almost unbelievable clarity of tone - clean, pure living sound. Most important, you can listen to the McIntosh for hours without listening fatigue or irritation. For performance that really makes a difference, enjoy the McIntosh, masterfully crafted for your lifetime satisfaction.

The 30 watt Amplifier model MC-30

Featuring the patented McIntosh Circuit

Guaranteed 0,5% maximum intermodulation distortion

Unity Coupling for performance plus

Beautifully Styled in Black and Chrome

Zero VU Line Level or any Tuner will drive to full output

Why the exclusive patented McIntosh circuit brings you purest high-fidelity sound....

The McIntosh circuit is fundamentally new. It provides practically 100% coupling between primary windings of the output transformer, by winding the primary wires together, or bifilarly. the high efficiency of class "B" amplification can be used for the first time with high quality performance. Wave form distortion, causing listening irritation, due to switching transients between each half of the class "B" amplifier is eliminated at all frequencies.

Before 1947, truly faithful amplified sound was severely limited by: (1) too much distortion;and 82) not enough power capacity. With the invention of the McIntosh circuit, less than 1% distortion became the performance standard which engineers everywhere had been striving to attain. The McIntosh has an inherent large advantage over conventional circuits. By bringing the output tubes electrically four times closer together the impedance is 1/4 that of the conventional circuits. The coupling to the secondary is improved by a similar factor of 4 to 1 since the primary to secondary turns ratio has been reduced 2 to 1. The 1/2 cathode, 1/2 plate loading provides a feedback factor of 12 dB, which with additional loop feedback, offers the lowest distortion, most stable power amplifier made.

Specifications
Power Supply: 117 - 125 volts, 50/60 cycles
Power Consumption: 135 watts at 30 watts output; 105 watts at zero signal output
Power Output: 30 watts continuous
Input Level:
Input-1 (pin jack and screw terminals and pin 5 of pre-amp socket) .5 volts to 30 volts, with gain control
Input-2 (pin 2 of pre-amp socket) 2,5 volts, (for use with McIntosh pre-amplifier equipment)

Frequency Range:
20 to 30,000 cycles ±.1 dB at 30 watts output
15 to 50,000 cycles ±.5 dB at 30 watts output
10 to 1000,000 cycles ±1 dB at 15 watts output
Harmonic Distortion: less than ⅓% if instantaneous peak power is below 60 watts for any
combination of frequencies 20 to 20,000 cycles
Impulse Distortion: negligible
Noise and Hum Level: 90 dB or more below rated output
Damping Factor: 12 or better for 4, 8 and 16 Ώ output, 16 for 600 Ώ
Input Impedance: 0,5 meg for 0,5 volt input and 0,13 meg for 2,5 volt input. 20 cycles to 40 kc
Output Impedance: 4, 8, 16 and 600 Ώ (600Ώ is balanced to ground)
Phase Shift: 20 cycles 3°, 20,000 cycles 9°
Tube Complement: Pre-Amp: 12AX7
Phase Inverter: 12A U7
Voltage Amp. 12BH7
Driver: 12AX7
Output: 2 - 1614
Rectifier: 5U4-GA
Auxiliary Equipment connection (“Pre-Amp Input” receptacle): Designed to power C-8 and other
McIntosh Pre-Amplifiers
Size: 13” x 8” x 8” high, chassis type construction
Weight: 30,5 pounds net
Finish: Chrome and Black

McIntosh MC 1000 Mono Power Amp

McIntosh Is thought by many to have invented the high fidelity audio amplifier in 1949. And, through continuous research, McIntosh has been reinventing it ever since with new developments and refinements that bring us ever closer to the goal of absolute perfection in musical reproduction. This proven amplifier technology, together with a number of technical innovations, has resulted in audio amplifiers that are capable of meeting the challenge of moder performance requirements.

McIntosh power output wattmeters indicate the true power that the amplifier delivers to the loudspeakers, regardless of speaker loads or impedance variations. Driven by circuitry that constantly measures both voltage and current, these illumniated, peak responding meters are extremely acurate, responding to 95% of full scale with only one cucle of a 2,000 Hz tone burst.

Power Guard a patented McIntosh circuit design , eliminates harsh clipping distortion without sonic side effects Not a “soft clipping” circuit or a limiter, Power Guard has no effect prior to the clipping point of the amplifier. A waveform comparison circuit continuosly monitors, the output signal and compares it to the input signal. Should distortion appear in the output signal, Power Guard acts by reducing the level of the input signal until distortion is reduced below clipping then restores the amplifier to full gain. because it is so brief, only thousandths of a second, you won’t hear the gain reduction. power Guard assures your listening pleasure and protects your loudspeakers from the damaging effects of clipping distortion.

McIntosh has provided their unique output autoformers in all of their “flagship” power amplifiers since the beginning of the “solid state” era. McIntosh output autoformers enhance amplifier performance by providing optimum loading of the output devices. This assures that maximum current may be delivered by the output circuit without exceeding the safe limits of the output devices. Additionally, autoformers provide expanded operational flexibility and contribute to long, consistent performance with far greater reliability.

McIntosh MC 1000 - The Power Amplifier for the most discriminating music listener.
features:
Dual Balanced advanced circuit design
McIntosh Output Autoformer for perfect amplifier-loudspeaker interface
2, 4 and 8 ohm output impedances
Gold plated, multi-way output terminals
1% metal film resistors and polypropylene capacitors
Peak output current of 160 amperes
An 8 inch illuminated output meter reads the true Power Output by measuring both output voltage and current simultaneously.
Balanced and Unbalanced inputs
Exclusive McIntosh Power Guard non clipping circuit

Specifications:
Power output: 1000 W mono
Distortion, IM & Harmonic: 0,005%
Output indicators: Meters
Output interface: Autoformers
Dimensions (W x H x D): 438 x 264 x 510 mm (17¼” x 10⅜” x 20⅛”)
Weight: 47,6 kg (105 lbs) net