Make/buy rumble/warp filter for pre phono inputs?

Zaikesman what were your results trying to transfer to CD-R without a filter? Are the warps so great that they use up all of the A/D's headroom? I've read that records can be de-warped by clamping the disc between two non-heat conductive surfaces and placing them in an oven at a low heat setting. Maybe someone will comment on this further.

I am currently transferring a large part of my vinyl collection to a digital format and I've come to the conclusion that for bad quality discs that computer-based DSP processing is essential. A record cleaning is the first step. Then once in the digital domain low-cut filters can remove rumble, gain can be altered as needed, pop/clicks and broadband noise can also be removed. All of this can be done relatively transparently. I use t.c. works Spark XL (Mac).

Onhwy61 - I will be using Sound Forge on some of these (which has the filter feature you mention) for scratches, but I suspect the results on the warped disks will be superior if the phono pre-preamp never has to deal with the heavy sub-bass modulation in the first place. As for the ADC, the meters on my HHB burner don't seem to register these frequencies' energy very well, but the overall result is poor enough, even when played back at low volumes, that some digital overloading is certainly a possibility. Of course, reducing the recording levels to compensate would reduce resolution and S/N ratio as well. While I haven't yet tried the digital warp filter, I will still want an analog pre-filter, not only for the reasons above, but also for making cassette copies, or just auditioning records in real time without having to digitize the signal and perform "post-production" on the computer.

Zaikesman, now I understand. I admire you for caring enough about music to save these less than perfect favorites, and now your filter idea makes perfect sense.

The problem is that putting a network of resistor and capacitor at the input of your RIAA stage can mess up the phono cartridge load and the input impedance of the preamp.

I suggest calling Conrad Johnson and tell them your situation. They have engineers that have probably already addressed this problem for others. My guess is that the filter should be in a tape loop. Other possibility is an equalizer, allowing you to cut and add for each situation as needed.