Magnatone Guitars!

New for Fall 2013, a complete guide to Magnatone guitars and the stories behind them!

1938-1960 Steel Guitars

1956-1963 Bigsby/Barth Era

1964-1966 Starstream Era

 

1963-1966 Custom Series

Faded grill cloth shows the speaker arrangementof both the stereo 1963 M14 and the late 1966 M10A.

 

While the Magnatone the 400 Series amplifiers had received electrical engineering advancements, such as reverberation, the general appearance was more or less unchanged since the 1957 200 Series. Meanwhile, Magnatone's biggest guitar amplifier competitor, Fender, had moved control panels from the rear to the front, and had adopted closed back cabinets for several of its higher wattage amplifiers.

Tough competition wasn't Estey's old problem, since taking over in 1961, attempts to get organ production off the ground had not gone well, and the company was struggling financially.

In 1963, Estey refocused its efforts in an all new series of guitar amplifiers called the Custom Series. The new line-up was an expansive range of amplifiers ranging from small eight-watt accordion amplifiers up to large three channel systems that could simultaneously handle multiple instruments and microphones. Magnatone enlisted John E. Demaree of Demaree Industrial Design to design the cabinet which allowed the control panel to face forward or backward, depending on the musician's preference.  1 

The People behind the Amps

 

Tony Price was promoted to Chief Engineer in 1963 and oversaw the entire product line. Later, after the company move to Harmony PA, he was promoted to National Sales Manager. Bob Warren was the mechanical engineer, and James Evans was the prototype engineer. Also important to the development of the amplifiers were Dick Stuber, the purchasing agent, and Maurice Varin, the machine shop supervisor. It was Varin's task to turn engineering designs into the stamped chassis, and set up the machinery to do so. Stubbe was in charge of getting components on the floor, which was as critical in the early prototyping stages as it was once the amps were in general production.

Chief Engineer Tony Price and an M20 on the cover of the 1965 catalog.

 

Marketing

 

The design and engineering behind the Custom Series amplifiers focused on the guitar. Tony Jerome was hired to help attract attention to the brand among guitar players, but old accordion habits die hard, and Estey sales consultant Roy Hunt wanted to continued to market Magnatone amps to accordion players. Due to Hunt's influence, the 1964 Custom Series catalog was heavily geared toward the accordion player.

Quality control testing at Torrance facility, however, was done with guitars. On the heals of the release of this series, Paul Barth was brought back to work with Price to develop a new guitar line, the Starstream Series, to compliment the amplifiers.

Design

 

The most distinguishing feature of the amplifier was the plastic top and integrated handle. The material was called "Royalite", a product of Rhode Island plastics manufacturer, The Royal Company. The top was symmetrical front to back, so the entire assembly could be installed with the controls facing the rear or the front, a feature that Magnatone touted in sales literature. The shape of the cabinet and the hand on top eventually led to the nickname "suitcase amp".

Printed in Pittman's amp book is a piece of false lore suggesting that these tops were surplus television tops. These tops were purpose built for Estey, and designed by the Demaree industrial design group on commission by Estey. The Royal Company produced the Royalite tops for Estey.

 

From a manufacturing point of view, the design lends itself to a varied product line without add a lot extra cost for additional product line models. The top plastic cover and it's chassis underpinnings could be shared among all many models.

 

The actual wood cabinet that housed the speakers could easily be varied for height and speaker configuration depending on the model.

This, no doubt, made efficient use of the cabinet shop's labor. time required for trim was greatly reduced by having rubber molding at the bottom of the cabinet and the Royalite cover on top Those two subtle design aspects, together with the rubber vertical side trim meant that the upholster had no corners to finish, and only had four sides to cover instead of six.

There were two Royalite tops made for these models: a large 27"x11.25" top for the M15, M13, and M12, and a smaller 23"x10.25" top for all other models.

Circuit Enhancements

 

The Custom circuits were a continuation of the 400 Series with several improvements. The most significant change to circuit design was a move to ultra-linear output transformers and 16 Ω speakers. This was done in effort to reduce distortion at louder volumes. For this, Estey engineers worked closely with Woodward-Schumacher Transformers in R&D to develop the unique 10KΩ:16Ω ultra-linear transformers. Similar development occurred with the EL34 based 3500Ω:8Ω transformers for the M13 and M12 amps (and later, M20).

Another big change to all circuits was a move from tube to a solid state rectifier. This change was even applied to the 96-10041 circuit that Estey continued to produce for the traditionalist accordion vendors like Tonemaster and Titano.

New high quality audio power tubes were used like the 7189A and the 6GW8. The latter was a high quality power pentode in the same glass envelope as a triode. A pair of these tubes in a push-pull circuit allowed Estey to use the two triodes as a gain stage and phase inverter, reducing the need for an extra 12AU7. For the powerful M12 and M13, Estey engineers adopted the 6CA7/EL34 power tubes (later a quad of 6CA7s would power the M20).

While lowering the cost of production was important, Estey engineers Tony Price and James Evans insisted on quality tubes, like Mullard pre-amp tubes, and G.E. power tubes.

Power Supply and Transformers

 

Inside the amplifier, engineer James Evans and machine shop supervisor Maurice Varin worked to standard the Custom's chassis to a single upper chassis could serve several models of amplifiers. Whether it was a stereo M14 or a four tube M7, the same standard steel chassis could be used for either. Also, Evans designed the chassis so all power tubes would be equidistant from their output transformer, a move to help lower noise and hum.

1965 M13 chassis was also used on M12, and M15 amps.

 

Another departure from earlier Magna build amplifiers is the placement of the power transformer, rectifier, and filter caps in a standardized small steel chassis mounted in the bottom of the cabinet. A wiring harness ran a bundle of wires (filament, main power 117VAC, and several B+ supply voltages) to the upper part of the cabinet and connected to the chassis with a Molex style connector. This engineering change was probably an influence of organ production.

Evans and Varin also devised the twin allen screw fastener design that allowed the upper control panel to be removed and serviced with the quick removal of the two side positioned allen screws.

The transformers were supplied by Woodward-Schumacher primarily, Later in the production run, Custom-Coil of Zanesville, Ohio also supplied power transformers (Custom-Coil was only 150 miles away from Harmony). I also have an original M12A power transformer without an EIA code, but with the codes "20-0024" and "C-T 200D". To maximize buying power, Magnatone used the same power transformers across several amp models.

Sound Design

 

Perhaps the most significant sound impact change Estey made to the Custom Series was the switch from open back to closed back cabinets. The newly designed cabinets were made from plywood. The front and back were 3/4" and the the rest was 1/2". The Partition sat above the speaker and below the upper chassis, creating what Magnatone called a compression chamber.

Speakers

 

It is hard to impress the amount of re-engineering that the Estey engineers applied to the Amplifiers, not only did the move to a closed back cabinet, switched from Oxford 12" speakers to heavy 14 ounce Alnico magnet 8" speakers for the M10, M14, and M15 amplifiers. For the M13 and M12, They used a large 27 ounce ceramic Jensen.

Ex-Estey engineer Jack Bartholomew, after leaving Estey sort of reinvented himself as a speaker representative (either for Oxford or Jensen, I'm not sure which). Bartholomew provided Estey engineers countless experimental speakers to help them get the sound right with the closed back speaker designs.

About a year into the production run, a switch from Alnico Oxfords to ceramic Jensens took place. This change was late in the gold era, sometime around late summer of 1964, but it might have been a gradual change where both speaker types were used for a few months.

In early 1965, the 8" Alnico's were dropped in favor of ceramic 12" Jensens. Any model with an 8" speaker was either dropped or redesigned to accept 12" speakers. Tweeters were dropped across the entire product line around this time as well.

Gold to Silver Motif Change

 

Production of these amps began in the summer of 1963 in Torrance. The last Custom amps were built in Harmony, possibly as late as 1967. The switch from the gold accent trim motif to a silver motif took place sometime between February and May of 1965 while production was still going on in Torrance.

Models that were redundant, or were not re-ordered by dealers were dropped. First the M2,M4, and M6 were dropped, then probably the M9 and M8. By the adoption of the silver motif in early 1965, the Custom line was the M7, M12, M10, and the M15. The M13 actually made the move to the silver motif as the M13A but in late 1965, it was replaced by the monster M20. The M14 was sold into 1965, but they were all gold motif.

Production and Sales

 

How did these sell? Not well enough to save Estey. These were premium amplifiers built with quality parts. Though Estey was able to cut costs without sacrificing sound quality with several of the design changes, list prices of the amp remained quite high, in large part due to Estey's distribution network and the need to do wholesale pricing.

The most common Custom amp was the M10, which in 1964, carried a $380 list price. At the time, a very similar guitar/accordion amp was the Ampeg Gemini I, which was $259 list price. Ampeg's Super Echo Twin, a stereo amp, was $379 list price, and Magnatone's comparable M15 was $580!

 

Replacement parts

 

Tubes:
ee 7189A and 6GW8 pages.

Top Fastening Screws:
The screws that hold the top to the cabinet are 1/4"-20 thread and need to be a minimum of 1" in length. The style of screw is called a "Flat Head Cap Screw" or "Flat socket head screw cap". The Hillman part number is H#883357 (Lowes). This does not come with the pilot shank, which makes centering the screw a lot easier. the pilot shank also pushes the interlock switch so the amp will operate. To engage the interlock, you'll need a screw longer than 1" (1.25"?)

Top Fastening Washer:
The washer that the screw fits to is a special part that Estey designed and had machined for their own use. These go missing, and there is little hope of replacing them with original parts. You can try a finish washer, or anything with a suitable diameter and an 82° countersink.

Casters:
Casters did not come on Customs. Estey sold a dolly with casters, but did not affix the casters directly to the cabinet. Music shops might have added them using hardware store casters of some type, and you can do the same if you are so inclined.

More Information

 

References

 

1: Patented. Demaree, South Pasadena, CA, assignor to Estey Electronics, Inc. Patent 199,622 Portable Musical Instrument Amplifier, filed Feb.10 1964, Patented Nov.24, 1964.

DA/MagnatoneAmps.com

 

 

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