Noise reduction for projectors?

[Joerg Polzfusz]

Hi!

Agfa's Sonector LS2 might be the only projector with an integrated noise reduction system:
https://www.filmkorn.org/super8data/...nector_ls2.htm
However, not only the used DNL system, but also Dolby B/C and HighCom 1/2 are also available as separate devices to be placed between reel-to-reel- or tape-recorder and an amplifier. Hence the question: Does it make sense to put such a device between projector and amplifier? Or is the quality of the sound coming from the projector so "weak" that it doesn’t make any difference? Did anyone ever tried this?

Thanks
Jörg

[Brian Fretwell]

I went to a "Widex" (the UK Widescreen Association annual event) where someone had used a DBX compander system on a 16mm magnetic film (it doubled the dynamic range, reducing noise in the process, but lost out to Dolby commercially). That sounded very good.

On 8mm I don't know if the top frequency reproduced on most projectors (especially at 18fps) would allow much improvement, but I did record some of my home made films with sound recorded on a Dolby cassette without the replay back Dolby equalisation so t hat the treble boosted track went to the projector. It didn't sound bad, but I doubt that it improved things very much as I had no playback equalisation from the projector to the amplifier.

[Steve Lee]

Some years back I had a go at recording onto super 8 at 24 fps from a digital source at the same time encoding it with dbx noise reduction. Dbx uses a similar system to High com, and both of these are nothing like Dolby noise reduction.

If the track has been encoded with dbx / High com noise reduction it must be played back through the dbx / High com noise reduction unit. If not it sounds like fingernails down a blackboard.
Unlike Dolby where by adding A,B,C ect noise reduction to the playback, even if the track has been encoded or not, you only lose the top end of the frequencies, as this was originally designed to take out the crackles and pops from optical soundtracks.
Dbx / High com uses a compression system that takes the full bandwidth and compresses it down onto the medium that otherwise would not be able to handle this amount of information. And by playing it back through the decoder it stretches it back out to the full bandwidth. This system is total joy to the ears and can send tingles down your spine, but there is a problem.

It was designed to be used with an analog medium that runs at high speed to make it work well, a minimum of 15ips. Super 8 sadly doesn't run fast enough to allow for the soundtrack to be recorded and read.
There is a slight improvement to the sound on the top and bottom of the bandwidth, it was from having a dbx unit that I use on my reel to reel recorder that allowed me to experiment with this. I don't recommend anyone going out and purchasing one, as you would get very little sound improvement for your money, as these units are now changing hands for crazy money.

As for using Dolby, it has similar problems. The soundtrack needed to be encoded to start with using one of the systems for it to work correctly. Just adding it to the playback will have the same effect to turning the tone control to bass, it will just take out the top end frequencies leaving the sound muffled.


Retro HiFi: DBX Disc - The best thing you probably haven't heard - YouTube