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Well, there is another partial explanation. Use a machine set for 3.75 in/s at 50Hz and use it on 60Hz, you'll make a recording at about 4.5 in/s made with 3.75 in/s EQ. I saw one of these on paper tape in the Provincial Archives of Saskatchewan. I didn't realize it at that time, but it seems like the most logical explanation. Fortunately, that tape had low-harmonic 60Hz hum on it, so I line-locked my oscilloscope and tuned the speed for a stable 60Hz. I got 4.4 in/s as the "proper" speed with that method, and that's within 2.2% of theoretical which is pretty good, all things considered. I did a quickie table If you used a 60Hz machine on 50Hz mains, then the tape recorded at the following speeds will play back at the second speed in the pair: Nominal Actual 1.88 1.57 3.75 3.13 7.50 6.25 15 12.50 30 25.00 This requires a machine that can shift downward by 16.7% Repeating the same exercise, but with a 50Hz record machine run on 60Hz mains, you get Nominal Actual 1.88 2.26 3.75 4.50 7.5 9.00 15 18.00 30 36.00 This requires a machine that can shift upwards by 20% Now, none of these sequences explains the 5 in/s in Don Chichester's email and 5.63 in Marie's original post, although this does explain the 4.4/4.5 in/s of the Saskatchewan tapes. Also another point to ponder. I believe some early portable tape recorders used spring-wound motors and mechanical governors for the speed control. This is distinct from the horrid "rim drive" machines from the 1960s -- which make all 3-inch reels suspect. No capstan at all, just a motor on the takeup reel and a rheostat in series between the battery and the motor. Cheers, Richard At 04:33 PM 3/4/2004 -0500, you wrote: >About 15 years ago a friend sent me his reel tape collection of interviews >he had made while doing a religious news show on the BBC. He asked only >that I might convert one or two tapes to cassettes for him. Upon playing >the tapeS! I found they were, in fact, recorded at about 5 ips! >I did the best I could at the time by increasing the size of the capstan >until it came close to c. 5 ips. >Evidently some recorders (for radio use???) recorded at 5 ips, or nearly >so. Else, why were there several such tapes? >Don Chichester