I have just picked up a mint condition 11-03 that works fine on radio but when playing a record the speakers distort particularly with increased bass. Any suggestions as to the most likely cause would be appreciated.

Greg

My initial guess would be a crook cartridge/stylus combo, which in turn could be caused by too much pressure on that end of the tonearm.

I tried the cartridge in another 11-03 and it played fine. I put it back into the latest acquisition and adjusted the stylus pressure to 4.5 grams but it still distorts.

Going by what some of the other members have this setting on, 4.5 grams still sounds a bit heavy. If possible to do so, I would recommend going lighter still.

One other thing worth checking is the sharpness of the stylus.

If we accept for the moment that the stylus/cartridge combo is okay, then it's got to be something in the signal path back to the amp, or in the amp itself.

Have you used contact cleaner on the radio/phono switch? I have been on wild goose chases before because I didn't do that first.

Have you used your ohmmeter to acquit the (presumably coax) signal cable of intermittent shorts or unwanted high resistance?

Seems I don't have the 11-03 schematic. Without the schematic I can't see if a phono preamp stage is involved because, if there is, that would be my next line of investigation.

Thanks to all. The problem turned out ot be a broken holder for the cartridge.

Just a comment on stylus pressure; 4 grams is about the minimum pressure for good tracking with a ceramic cartridge, and 6 grams is the usual minimum for a crystal cartridge. Decreasing the stylus pressure below the maker's recommended weight will result in distortion on loud passages and eventual groove damage; the stylus loses close contact with the groove walls and starts to tear chunks off the high spots. Higher pressure will increase the wear on the stylus and records, but should not cause distortion unless the stylus is bottoming out or the cartridge is scraping the record surface. When in doubt, go for a slightly higher pressure. You can reduce the wear by keeping the stylus and records clean, and replacing the stylus regularly. I check mine with a microscope. What you should look is flat wear spots or chipping.