Shellac / acetate / cardboard NR

Greg Miller · December 8th, 2022, 10:50 PM

Mr. Hart:

There is an excellent (unbelievable, actually) program called Capstan which can remove wow and flutter. I've never used it myself (of course it's pricey) but I've heard demos that are quite impressive. The other option (used by at least one of the "old time radio" resellers here) is to use a turntable with no center post, and to center the discs manually to eliminate wow caused by holes that were punched slightly off-center.

As for the info about past EQ practices, two possible sources come to mind. Take a look at the documentation for Audacity, and/or the documentation for the Diamond Cut line of NR products. I'll be surprised if you don't find something relevant from at least one of those sources. [Disclaimer: I was a beta tester for Diamond Cut several years ago. I have no present connection with the company. I do feel their documentation is unusually thorough as might be helpful especially to beginners.]

Some further info about Dolby. Many years ago, someone modified a Dolby Type A card, in an attempt to make a single-ended NR playback system (downward expansion only). The amount of expansion was controlled manually by the user, rather than by some factory calibrated threshold. IIRC Dolby designated this a Cat 43 (or some such name). Also IIRC there is now a separate company writing software which they say operates more or less like the Cat 43 did. In fact I have a card cage with seven Dolby A cards, and I was tempted to modify at least some of them for manual control. But after actually trying a Cat 43 for a few weeks, I concluded that it wouldn't solve the problem I was working on at the time, so my cards remain unmodified.

December 8th, 2022, 10:50 PM	#16
Greg Miller Trustee Join Date: Jan 2011 Location: Pennsylvania Posts: 1,786	Re: Shellac / acetate / cardboard NR Mr. Hart: There is an excellent (unbelievable, actually) program called Capstan which can remove wow and flutter. I've never used it myself (of course it's pricey) but I've heard demos that are quite impressive. The other option (used by at least one of the "old time radio" resellers here) is to use a turntable with no center post, and to center the discs manually to eliminate wow caused by holes that were punched slightly off-center. As for the info about past EQ practices, two possible sources come to mind. Take a look at the documentation for Audacity, and/or the documentation for the Diamond Cut line of NR products. I'll be surprised if you don't find something relevant from at least one of those sources. [Disclaimer: I was a beta tester for Diamond Cut several years ago. I have no present connection with the company. I do feel their documentation is unusually thorough as might be helpful especially to beginners.] Some further info about Dolby. Many years ago, someone modified a Dolby Type A card, in an attempt to make a single-ended NR playback system (downward expansion only). The amount of expansion was controlled manually by the user, rather than by some factory calibrated threshold. IIRC Dolby designated this a Cat 43 (or some such name). Also IIRC there is now a separate company writing software which they say operates more or less like the Cat 43 did. In fact I have a card cage with seven Dolby A cards, and I was tempted to modify at least some of them for manual control. But after actually trying a Cat 43 for a few weeks, I concluded that it wouldn't solve the problem I was working on at the time, so my cards remain unmodified.