Audio restoration - Page 1
Forum section: electronics / projects

author: antenna
author_rank: Frequent Contributor
timestamp: January 04, 2022, 04:07:52 pm
content: I have been copying reel to reel's of my great uncles band to the computer. Aside from a bit of degradation from being played many times and stored for about 70 years, my grandma was sitting a little too close to the bass amp when she recorded the live shows. My question is two-fold. 1- I read somewhere that the Library of Congress uses heat (about 130°F?) to recover degraded reels. The reels are not shedding oxide yet. Is this technique real, and does anyone have enough experience using it to give me some advice? 2- Some of this distortion is from over-driving the microphone. I was wondering if it is possible to repair that. I sort of envisioned using Goldwave to separate the different frequency components and pass the low ones through a filter and reassembling the audio. I figure this will be difficult with the variation of bass tones and the harmonics created by the flat topping, and I fear this will only work if done one chord at a time, if at all. Again, looking for some direction because these recordings mean everything to my grandmother and they are the only ones known to exist. Thanks!

author: Shock
author_rank: Super Contributor
timestamp: January 04, 2022, 05:24:42 pm
content: https://arstechnica.com/science/2020/04/the-chemistry-of-why-baking-degraded-reel-to-reel-tapes-can-reverse-damage/Sounds legit to me. If your tapes aren't out-gassing though I don't see any advantage in risking that.I would consider doing what you suggested yourself, there are probably plenty of books on remastering audio. The latest techniques use machine learning.None of this is really electronics related though is it?

author: antenna
author_rank: Frequent Contributor
timestamp: January 04, 2022, 09:31:34 pm
content: Quote from: Shock on January 04, 2022, 05:24:42 pmMy mindset was in making a series of audio filters, but being my question was not specifically regarding that, you are correct. Apologies for the non-electronics related post and thank you for the reply.

author: Circlotron
author_rank: Super Contributor
timestamp: January 04, 2022, 09:45:05 pm
content: Quote from: Shock on January 04, 2022, 05:24:42 pmI’d say it’s more legit than cat pictures or cooking.

author: John B
author_rank: Frequent Contributor
timestamp: January 04, 2022, 09:51:49 pm
content: Before any physical experiments on the medium, I would try to see how much you can achieve in software. Noise reduction and clipping restoration come to mind. Noise reduction takes a sample of the background noise by itself and tries to subtract it from the rest of the recording, while clipping restoration makes some educated guesses about the waveshape at the maximum excursions. The key thing is to take a sample of the recording before trying anything permanent with the physical medium.

author: Shock
author_rank: Super Contributor
timestamp: January 04, 2022, 10:04:15 pm
content: It's always worthwhile messing around on projects for electronics experience.But it sounds like you are trying to needlessly reinvent the wheel. There are digital audio processing techniques that you wouldn't be able to improve on within your lifetime. Just putting it into perspective, a lot of people use emotional brain rather than logical brain when it comes to audio.There is probably someone on fiverr that does this work all the time and can knock it out for you in an afternoon. As long as you know this before going in, play till your hearts content.

author: antenna
author_rank: Frequent Contributor
timestamp: January 04, 2022, 10:52:26 pm
content: Quote from: John B on January 04, 2022, 09:51:49 pmI recorded everything onto the computer in wave format and will keep that saved separate from edits. With the medium already backed up digitally, I was thinking it would be of benefit to try to improve the reels and re-digitizing before attempting the restoration process. The only program I have is Goldwave from the XP era, but it does a great job at hiss removal and is loaded with features. I will see if there are other more advanced programs, but I cannot pay the thousands most companies want for their editing software.

author: NiHaoMike
author_rank: Super Contributor
timestamp: January 04, 2022, 11:23:36 pm
content: Might want to look at DIY 3D printer filament dryers to do that, the temperatures involved are similar.

author: Martian Tech
author_rank: Regular Contributor
timestamp: January 05, 2022, 03:01:12 am
content: iZotope RX 9.