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Audio & Hi-Fi Ferrograph Series 6, model 632.

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PYE625
(@pye625)
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The motor and bearings are all back together and I used a synthetic grease, Loctite super lube. It seems to be perfectly ok and the machine is operating well.

Although this is a fine machine, I somehow don't think I will be replacing my trusty Revox A77 with it. The Revox is quite a bit more refined in pretty much every area, so for regular use, it will stay.

Go forward just a few years and the Japanese decks, such as top of the range Akai and Technics etc, leave the Ferrograph in the dark ages. But that is not the point. It is like comparing a modern car with a vintage classic.

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Topic starter Posted : 21/05/2022 10:36 pm
PYE625
(@pye625)
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A minor criticism is the slight difference in level between the upper and lower track (L&R stereo) tape playback only. This is really only included as a matter of interest, as I will be doing nothing to modify or interfere with the design.

Basically, there is perfect scope for adjustment by preset controls R52/4 for equalisation of both playback tracks for the differing tape speeds, but nothing to compensate for the slight difference in overall audio level from the stereo playback head.

Considering the below circuit (upper track only for simplicity), SW7 selects tape playback or feed from the input stages. R56 is the volume control and R57 a preset level control. If R57 say, is adjusted for similar (L&R) levels of tape playback, you then mess up the balance of the input levels. In other words, there is no facility of adjustment for the head playback level alone. (R74 preset control between the cathodes of the input to the playback amplifier is an adjustment for minimum crosstalk level. SK2/3 connect directly to the playback head).

The only way to achieve perfect playback balance is to adjust the main volume control of either channel. As I said, a minor niggle, but could have been solved by an additional preset control probably at the output of C34 prior to the volume control and preset R57.

IMG 6247 50
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Topic starter Posted : 15/06/2022 7:49 pm
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PYE625
(@pye625)
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Posts: 4980

I should have perhaps added, purely for addition to the above, that a tape having exactly equal volume levels upon both tracks was played at the time.

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Topic starter Posted : 15/06/2022 9:55 pm
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