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Topic: Eumig 802
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Paul Adsett
Film God
Posts: 5003
From: USA
Registered: Jun 2003
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posted December 12, 2008 10:55 AM
Hi Steve, The way I set up my Yamaha 10 band graphic equalizer is to notch down -6db at 120 hz, while actually boosting the bass levels by +6db at 30,60, and 240 hz. The hope is that this produces a very sharp 12 db notch around 120hz so you don't lose too much bass. It certainly works a lot better than a simple bass control. I only do this when running my Eumig 820. On my version 2 GS1200 there is no significant hum, so I do not notch out at all at 120hz. But for my older version 1 GS, I do notch out the hum just on track 2, which has an audible level of hum. I also use the equalizer to boost treble levels on 'muddy' sounding mono film tracks, and I also totally notch out (-12db) all films at 16khz to eliminate hiss. All told, I find the equalizer a great tool for improving the playback quality of super 8 sound tracks. Just to note, that the hum problem on the Eumig 800's was essentially eliminated on the later 900 series machines, where the transformer was located much further away from the sound head, and they also improved the shielding of the head.
-------------------- The best of all worlds- 8mm, super 8mm, 9.5mm, and HD Digital Projection, Elmo GS1200 f1.0 2-blade Eumig S938 Stereo f1.0 Ektar Panasonic PT-AE4000U digital pj
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Martin Jones
Phenomenal Film Handler
Posts: 1269
From: Thetford , Norfolk,England
Registered: May 2008
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posted December 12, 2008 12:44 PM
There are simple, but VERY effective notch filter circuits around using Operational Amplifiers and resistor/capacitor combinations. Using these, it's possible to obtain 40dB (or better) reduction at specific frequencies. 50, 60, 100, and 120 hz are the important ones (depending where you live). As suggested, these are used between the Line Out jacks of the projector and an external amlifier and speaker. As I've said before, commercial "hum filters" intended to go in the speaker leads are USELESS.
Martin
-------------------- Retired TV Service Engineer Ongoing interest in Telecine....
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