Gearslutz.com - View Single Post - 2" tape : 30 ips : is anybody out there?when did the speed change?stories..thoughts

Mark Ettel · 29th May 2006

> think you have that backwards.
30 has a bump in the 120 area... 15 has the bump way down lower.
30 also rolls pretty sharply down on the low end.<

ww has it correct here. One of the reasons that 15 ips has a head bump on most machines is the fact that the architecture of the heads is optimized for flat response at 30ips. Very long wavelengths are difficult to reproduce so extra sensitivity is need in this range. Another factor is the "fringing" effect that occurs at long wavelengths, where low frequency energy is picked up by adjacent tracks. A 50hz signal is almost two feet long on the tape at 30ips, and that energy "bulges" out and is picked up by the tracks next to it. What this means at 15 ips is that a head bump, centered around 50hz depending on the machine, of 6db or more can occur. This usually won't happen on a machine with heads optimized for 15ips.

>and all three sound different.
the ProTools mix does NOT sound just like live<

I've worked with just about every type of recording system an the only thing that has sounded so close to the buss that it was probably the cable run back to the console that made the difference was Direct to Disc recording. I'm talking about vinyl disk, not hard disc. Back in the day when I was a young whippersnapper, I was privileged enough to be involved in a couple of the D to D projects Doug Sax used to do with Bill Schnee engineering for his Sheffield Labs label. The playback from the lathes was simply amazing. Flawless. When Bernie Grundman opened his own facility next to Ocean Way Recording, we did quite a few D to D's there. During tests, we could monitor the disc while it was being cut with a phono cartridge playing the disc right after the cutter. Perfect. It's amazing how accurate a mechanical system could be. The only thing that came close was an Ocean Way modified Ampex ATR 102 running at 30ips, which was backup for the lathe. The new DSD recorders sound excellent, but it took all that to approach the sound quality of a heated ruby cutter head making a little squiggly groove in a piece of acetate. Amazing isn't it.

29th May 2006	#19
Mark Ettel Gear Head Joined: Nov 2005 Location: Studio City, CA Posts: 43	> think you have that backwards. 30 has a bump in the 120 area... 15 has the bump way down lower. 30 also rolls pretty sharply down on the low end.< ww has it correct here. One of the reasons that 15 ips has a head bump on most machines is the fact that the architecture of the heads is optimized for flat response at 30ips. Very long wavelengths are difficult to reproduce so extra sensitivity is need in this range. Another factor is the "fringing" effect that occurs at long wavelengths, where low frequency energy is picked up by adjacent tracks. A 50hz signal is almost two feet long on the tape at 30ips, and that energy "bulges" out and is picked up by the tracks next to it. What this means at 15 ips is that a head bump, centered around 50hz depending on the machine, of 6db or more can occur. This usually won't happen on a machine with heads optimized for 15ips. >and all three sound different. the ProTools mix does NOT sound just like live< I've worked with just about every type of recording system an the only thing that has sounded so close to the buss that it was probably the cable run back to the console that made the difference was Direct to Disc recording. I'm talking about vinyl disk, not hard disc. Back in the day when I was a young whippersnapper, I was privileged enough to be involved in a couple of the D to D projects Doug Sax used to do with Bill Schnee engineering for his Sheffield Labs label. The playback from the lathes was simply amazing. Flawless. When Bernie Grundman opened his own facility next to Ocean Way Recording, we did quite a few D to D's there. During tests, we could monitor the disc while it was being cut with a phono cartridge playing the disc right after the cutter. Perfect. It's amazing how accurate a mechanical system could be. The only thing that came close was an Ocean Way modified Ampex ATR 102 running at 30ips, which was backup for the lathe. The new DSD recorders sound excellent, but it took all that to approach the sound quality of a heated ruby cutter head making a little squiggly groove in a piece of acetate. Amazing isn't it.