eico st 70
- Thread starter Tronhead
- Start date
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FalconEddy
Audio Mastering Engineer
Well, if you can't hear anything, you may have some type of unwanted subsonic frequencies getting to them.
It could be some type of subsonic oscillation (10Hz as an example) in the output stage from something you perhaps added in the rebuild.
Have you attempted to increase/decrease the bass pot controls to see if that affects the way/depth the woofers move at idle?
Also check the Loudness and Lo Filter switches to see if either of them cause/remove this effect. Then check to see if it happens in all modes. e.g. phono A, phono B, etc.
Although there shouldn't be anything getting to the speakers with the volume level fully counterclockwise, leaks are possible if the pots and switches aren't completely clean.
Do you have new 7591's, or are they the originals?
. . Falcon
It could be some type of subsonic oscillation (10Hz as an example) in the output stage from something you perhaps added in the rebuild.
Have you attempted to increase/decrease the bass pot controls to see if that affects the way/depth the woofers move at idle?
Also check the Loudness and Lo Filter switches to see if either of them cause/remove this effect. Then check to see if it happens in all modes. e.g. phono A, phono B, etc.
Although there shouldn't be anything getting to the speakers with the volume level fully counterclockwise, leaks are possible if the pots and switches aren't completely clean.
Do you have new 7591's, or are they the originals?
. . Falcon
