The magnitude of the vibration of the AC induction motor in old times when Marantz Model 7 was first released is much larger than that of today's modern high-end turntable system. This will result to the necessity of the subsonic filter.
The magnitude of the vibration of the AC induction motor in old times when Marantz Model 7 was first released is much larger than that of today's modern high-end turntable system. This will result to the necessity of the subsonic filter.
But according to Jeff's article, it is better to set the cutoff frequency to a slightly lower frequency. This is possible by replacing the C63's 0.01 MFD SPEC MC-DA mica capacitor with our 0.012 MFD Ultimate Ruby Mica capacitor.
The change from 0.01 MFD to 0.012 MFD of C63
lowers the calculated cutoff frequency of the
first stage from 48.2 Hz to 40.2 Hz.
This also results to:
・rich tonal contrast
・sharp focus of the sound
・improved tonal balance
<References>
Jeff's Place (Last viewed date : 11/9, 2020)
https://jeffsplace.positive-feedback.com/a-guest-article-from-mr-shirokazu- yazaki-my-adventure-with-my-old-marantz-model-7-part-9/
A modified Marantz Model 7 replica. When the Marantz Model 7 appeared in 1958, the main playback sound source was analog LP and FM broadcasting, so the tone amplifier receiving the Phono EQ output did not need to extend the bass range.
In order for the bass to be expressed naturally, a new capacitor must be installed. Our Ruby Mica is a breakthrough in sound quality thanks to its outstanding characteristics.
Jeff's article shows an expanded schematic of this part of Marantz Model 7.
The sound quality has been greatly improved as a result of changing from 0.01 MFD to 0.016 MFD. By simply replacing a few parts, the sound quality was greatly improved, and the sound was closer to realistic sound. Jeff also mentioned in the article that he strongly recommends his comrades who are Marantz Model 7 enthusiasts.
<References>
Jeff's Place (Last viewed date : 12/7, 2019)
https://jeffsplace.positive-feedback.com/a-guest-article-from-mr-shirokazu-yazaki-my-adventure-with-my-old-marantz-model-7-part-8/?fbclid=IwAR3e5fIVKJoypuTmo7JkP61FiHd_hZU1uYKVl8qyGyZzSjJNghr9ozn8th4
The model 7c PHONE jack RIAA equalizer uses the following two capacitors. 5600pF and 1600pF (red part in right figure). The original capacitors used in the Marantz7c use film-type capacitors with very high immunity. This part uses Matsuzaki Electric's acoustic capacitors that use ruby mica, which is considered to be higher quality in terms of tone and transparency than conventional silver mica capacitors.
The orange capacitor is for 5600pF.
Two brown capacitors near the 560k resistor are 1600pF (1500pF).
After replacing the capacitor.
Two replacements of 1600pF.
Replace 4 Ruby Mica inside.
<References>
SOUNDARIES （ Last viewed date : 12/7,2019）
http://soundaries.com/2016/06/spec-ruby-mica-in-model7.html/