HELP Digital bad, vinyl good???

Swampwalker: your description is right in how most preamps work, but as Tvad mentions, we aren't sure that's how this specific preamp works. His suggestion to disconnect the phono rig from the preamp ( interconnects, ground wire, power cord, etc... ) is where i would start. After that, it is a matter of tracking down the offending tube in the preamp, if there is one ( or two if dual mono ).

As a side note, the phono stage may not drive the line section as hard as your CD players do. As such, you might not hear as much distortion from the phono rig as you do the CD player. This would be due to the increased heardroom / lack of drive from the phono stage. This is just a guess though, so don't put too much faith in it. Sean
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The BAM module is basically an active equalizer with a high pass filter built into it. This reduces driver excursion below port resonance, lowers distortion, reduces power consumption and increases power handling.

Evidently, either your phono system isn't capable of very deep bass and / or the records that you were playing didn't have a lot of deep bass on them. Obviously, the CD's did, which is what caused the distortion that you heard. This is one of the drawbacks of using a vented design without some form of active equalization and / or a steep high pass filter. Now you've actually heard the distortion that i've mentioned many times before when discussing vented designs and the woofer(s) becoming "unloaded". Not pretty, is it?

Glad that you were able to figure things out without any real down-time or great expenditure on your part. Sometimes, as is the case here, the simple stuff is the easiest stuff to overlook. Sean
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Obviously, i wasn't there to hear what was going on, so i could be off in left field. Having said that, over-excursion of a mid-woofer can lend a distortion / vibrato effect to midrange and treble frequencies. Don't know if this is what you were hearing, etc... In severe cases of over-excursion, the driver will mechanically bottom out. This sounds VERY scary, as it should. Sean
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