A history (I think pretty accurate - corrections welcome). When commercial stereo tapes began in the early mid 1950's (several years before stereo records) they were 7.5ips 1/2 track tapes, often dubbed in real time (I have about 40 of those early tapes - mostly RCA, some Westminster, Everest, Capitol and a few other labels.) They were very expensive. My RCA Gaite Parisienne Fiedler was $14.95 for the reel when LP's were $3.98. so about 4 times as much as LPs. The main costs were the tape (materials cost) and the speed of duplication (labor costs).
So then, the goal became reducing costs. Two things were done. First, lower tape costs. Change from 1/2 track to 1/4 track which reduced the cost of tape by half. Then reduce the speed (mainly for pop albums) from 7.5ips to 3.75ips, again reducing the cost of the tape by another half.
Second was to increase the speed of dubbing - I think it went up to 16 or 32 times, lowering labor costs. In addition distribution systems were set up to do dubbing on multiple machines simultaneously. Ampex had a major complex just for duplication of tapes. 1/4 track tapes had all four tracks recorded simultaneously, meaning that two of the tracks were recorded backwards (usually side 1 - tracks 1 and 3, so that when the tape was finished, side 1 began on the outside of the reel, ready to play.)
To lower the effect of tape hiss and tape overload, dolby B was introduced for reel to reel tapes (not sure whether this was at the same time that dolby B was introduced into cassettes (which also reduced the speed to 1.875ips and the tape width to 1/8 inch from 1/4 inch.). My dolby B tapes seem to start around the late 1970's.
Some tape companies mitigated the loss of sound quality by dubbing at lower speeds (still faster than 1 to 1) like Barclay-Crocker, which licensed almost exclusively classical titles and also used dolby B in all their releases (except for a few in dbx II). There were also some very small companies which continued to do real time duplication. I have a few DTR tapes made by Bob Sellman in real time. These were both done in the 1980's and available directly from the companies.
My tape collection includes over 500 commercial 7.5ips tapes from this era, including both 1/2 track and 1/4 track tapes, and a fair number of dolby B encoded tapes (many from Barclay Crocker). (I don't buy 3.75ips tapes). The quality of many of these tapes are excellent, a few even outstanding. Many are just OK. 1/2 track tapes, particularly those dubbed in real time can be outstanding. One big advantage over vinyl, is that with tapes there is no inner groove distortion. Psychologically, one can more easily adapt to a constant low level hiss than scratches and uneven surface noise.
With my collection of 15ips 2 track tapes, I find I don't play my 7.5ips commercial tapes very often. However, most of the titles I have on the latter are not available commercially on 15ips 2 track tape.
Larry
