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I forgot to mention ... what about half-speed mastering? So there you're having the tape machine treat the transients at half the original velocities (that might be the wrong word). How does that compare to original-speed fidelity? My point is, it's an interesting debate and I'm not convinced there's a "right" answer as long as you can have original-source azimuth alignment and make sure polarity is maintained. I don't consider a magnetic tape playback system capable of perfect fidelity from tape to tape and machine to machine, so I think you can't set hard and fast rules and, joyfully for some of us and dreadfully for others, we must use our ears and aesthetics as the final decider. -- Tom Fine ----- Original Message ----- From: "Tom Fine" <[log in to unmask]> To: <[log in to unmask]> Sent: Thursday, October 08, 2009 7:32 PM Subject: Re: [ARSCLIST] Reverse engineering > This backs up what I have experienced here. The reverse-copied tracks can (but don't always) sound > "crisper." And yes, Richard is right -- reverse polarity. You will probably hear a difference with > that, too. > > As I said in my previous post, I'm not sure what's "right" vis-a-vis fidelity since you're not > playing it back on the machine on which it was recorded and all head-playback > electronics-alignment combos have some sort of sonic signature, be it mild or not. > > Finally, Richard is 100% right about low-fidelity oral histories. It gets more debate-worthy when > you get into an instance like well-made music recordings that are 1/4-track 7.5IPS and you want to > ingest all 4 tracks at once. > > Oh, and regarding duplicated tapes ... the unfortunate truth is that there is almost never an > azimuth match in the two "sides." The reason, especially with quarter-track 7.5IPS reels duped > back in the "golden age" days of the late 50's and early 60's, is that there were two record heads > that were almost never in perfect alignment. I think SOME but not all later cassette dupers had 4 > stacked tracks, but most formats from the days of Ampex 3000 series dupers had pairs of record > heads, one for the "side A" tracks and one for the "side B" tracks. 8-tracks would be four and > four, from the heads I've seen and dupers that have been described to me. > > The practice I ended up adopting for quarter-track tapes with music is just charge for the time > required and ingest one side at a time with an azimuth tweak each time. With home-made tapes, if > the azimuth was _really_ well aligned at the factory, you can sometimes get away with a 4-at-once > ingestion, but a sharp-eared client can hear the difference with transients and may not like his > two sides sounding different. > > -- Tom Fine > > ----- Original Message ----- > From: "Robert Cham" <[log in to unmask]> > To: <[log in to unmask]> > Sent: Thursday, October 08, 2009 6:03 PM > Subject: Re: [ARSCLIST] Reverse engineering > > >>I should think that it isn't relevant to digital copying at all, but back in the analog '70s we >>used to high speed dub reel to reel tapes backwards because seeing a decay as a transient was much >>easier on the electronics than an attack, especially a percussive one. That was the >>recommendation of Ampex, who built our duplicators. >> >> Bob Cham >> >>>Back in the day when duplicating tapes was a day job for me, they said that side 2 of cassettes >>>duped ay high speed both sides at once would sound better than the side 1 would. Never made much >>>difference on cassettes, especially at 64 or 128IPS dupe speed, but some people told me copying 2 >>>tracks worked better in reverse too... They said the electronics could respond to transients >>>backwardsbetter than forwards. I have no empiric evidence of this though. >>> >>>Just old tape tales by now, but this had me thinking back... or backwards! >>> >>>I have transferred some quarter track tapes doing all four tracks at once top a four channel A/D, >>>and not noticed a significant difference, but it is easier to do them one side at a time as then >>>they end up tails out, as long as it is an hourly job and not a mass flat fee transfer project. >>> >>>Hope this isn't irrelevant! >>> >>>Lou >>>Lou Judson >>>Intuitive Audio >>>415-883-2689 >>> >>>On Oct 8, 2009, at 1:59 PM, Richard L. Hess wrote: >>> >>>> >>>>>It's not the digital realm, its the way the reel electronics handle transients and phase >>>> >>>>There appears to be waveform differences between playback in the two directions after accounting >>>>for the polarity flip. To my ears, this is an acceptable tradeoff for copying oral history tapes >>>>in half the time. This is especially true of mid-to-low-fi recordings such as some 3.75 and most >>>>1.88 in/s reels. >>>> >>>>Cheers, >>>> >>>>Richard >> >