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Over-amplified bass from phono stage?

I just recently entered the world of vinyl, and I've been having some scary incidents. I am currently just using the phono stage in my cheapie adcom preamp, and when the volume is turned up past 1/3 or so, the woofers in my speakers start going wacky, moving in and out, with very high excursion but nothing audible. This is in addition to the music that supposed to be coming out. This also happens when the record pops or whatever. Is this a problem with my phono stage, or is my turntable (a pro-ject 1, grado zf3 combo) set up improperly, or is this just a necessary part of analog music? By the way, I only reluctantly buy CD's now. The sound just isn't comparable. Thanks!
gvibes
stevea
3 posts
 
This is common in phono stages that don't have infrasonic filters. IF you watch your tonearm and cartridge when this occurs, I'm certain that there is much lateral travel occurring. Certain tonearm / cartridge combinations don't mate well due to compliance differences. This could be aggravating the situation. I don't believe that changes in setup would help. Time was, you could buy in-line filters to insert in the interconnect between the turntable and phono stage. I don't know if these are still available. Good luck! Steve
woodrow
19 posts
 
Oh Boy, did we ever fight that problem back in the days before CD's! I'm not telling my age but my first "high end" turntable was a Garrard model 50 (yuck!). I think Steven has touched on your problem however, I suspect that rather than an ifrasonic situation you may have a subsonic problem. Please believe that your speakers don't like that high excursion and neither does your amplifier. Although probably not totally accurate I offer the following analogy: Think of your turntable, arm and cartridge combination as a microphone. If you walk across a hardwood floor and the vibrations of your footsteps travel to your rack and then the shelf and then the turntable, the turntable (microphone) will pick this up and send it through the signal path along with the music. Bass information from your speakers will do it too. Big time! This can come from the vinyl itself due to warps etc. Subsonic filters will obviously filter most of that out but the problem is still there and still affecting the overall sound of your turntable system. Also, depending on your speakers, these filters can remove some of the lower bass information that you want to hear. Isolation is the answer. There are some good isolation platforms available today that we didn't have years ago. Back then, a friend had a Fried Model H speaker system with a transmission line subwoofer that was to kill for. We finally ended up with the speakers being the only component in his listening room. The rest of his components were in another room and the base of his turntable was packed with duct-seal. Problem solved. Isolate that table by whatever means necessary be it a platform, cones, etc. As far as subsonics from the vinyl itself I would suggest a record clamp. At least that will help with warps and keep the record pressed to the mat. Good luck and happy listening.
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