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Many audiophiles must be very familiar with the Marantz Console 7 pre-amplifier. Many could have even owned it or its variants for many years. This is already a classic design, and it is as hot as it was first introduced to the market. Today, digital audio has already nearly replaced all traditional analog signal sources, but the Marantz 7 can still be considered the best because of its rich, golden sound. The original M7, or other equivalent tube amps, are actually very old; some perhaps might be nearly half a century old. Even if very well taken care of, oxidation and aging of components must have taken toll on such classics. Even when brand new, the old components might not be ideal due to the standard of manufacturing in the older days. (However, classic capacitors and resistors have their own characteristic nice sound). If one is to invest in an original M7 today, itmay well be more of profound feelings of the golden age than true audio. Having heard the original M7, the author is very impressed by its sound. The authorI has visited www.ebay.com recently, and saw an almost new M7 asking for at least US$1000. However, there were still many people bidding for the old classic.
As early as 1981, the American audio DIY magazine ‘The Audio Amateur’ discussed about the M7 with great interests. Modifications, improvement and maintenance tips were widely shared and argued. Certainly, there must be numerous M7 still in service in the US, but they must be so old and many of them badly need a good over haul. The original designer of M7, Mr. Sid Smith provided modification services for the M7 in the US. However, the wait is so long it might as well do it by yourself. The author has once heard a very old system playing Chinese music in China town, Singapore. The pre-amplifier was the M7 and even though both extremes of the frequency range were lacking, the sound was transparent from the pair of old unidentified horns.
Long ago, the M7 circuit already tempted the author who was still a college student. The author enjoyed collecting M7 related publications and DIY information, and arrived at three huge files of documents. Perhaps partly due to the ‘Peking Duck Style’ education system the author had; the author was only able to copy the design part-by-part, connection-by-connection, and was unable to analyse the circuit, and did not have the guts to modify it. The author was getting confused on starting to get designs from VTL (such as the Ultimate) and the McIntosh C22. Which can be the best design? Well, if you have all the amplifiers at hand, it will be easy to compare. However, at that time my friends only enjoyed a Walkman or Minicompo. They would have thought talking tube must be something from Mars. 0 |
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Many friends in Hong Kong, US and Japan must be very familiar with the DIY version of the M7. Many interesting articles about the M7 have been published, with thousands of field reports of building it logged. This shows that M7 has an authoritative position in the audio world. Even for today, the M7 line amp design is considered as a good and advanced design.
The expert who writes for ‘The Audio Amateur’, also a famous IC designer, Mr. Walt Jung has published articles related to M7 modification. He employed modern components to rebuild the power supply, and uses LM317 IC to regulate the voltages to a very stiff and stable level. The sound compensation facilities, tone controls, filters, were all removed. This total changed the sound of the M7, but this was the sound every one wants: great dynamics, transparent, smooth and nice. The more importantly the new M7 makes many transistor pre-amps sound horrible, and even terrible.
