Found this on the web.Can anyone please explain to me in "simple" english what exactly the following paragraph means?Not being very technical oriented i find it a little hard to comprehend. thank you SUN TAPE ECHO "By 1954 Sam Phillips had upgraded his equipment and installed two Ampex 350 recorders: one a console model and another mounted behind his head for the tape delay echo, or slapback". See http://www.history-of-rock.com/sam_phillips_sun_records.htm The slapback/echo tape machine (#1, the mounted model) would typically record a dry signal from a local mike. The tape with the local signal, recorded less than a second ago, then reaches the playback head of the same machine. (Length of delay is governed by the tape speed of the echo machine.) The played back dry, local signal then goes into the console where it is mixed with signals picked up by all the microphones in real time, including the one also recorded on the reverb tape machine. The console tape machine finally records the mixed signal on its only track. Assume a distance between the recording and playback head of 4 inches and echo tape speeds of 7.5 ips: Delay = 4/7.5 = 0.53 seconds (most likely the most common echo tape speed). 15 ips: Delay = 4/15 = 0.27 seconds (When It Rains It Really Pours). (Update July 2004: 7.5 ips as the common speed of the echo tape machine has been confirmed by Roland Janes of Sam Phillips studio - thanks!) So the distance between heads would correspond to the longer path if the wet signal is delayed with about half a second (7.5 ips). Speed of sound at 25 centigrades (77 F): 347 m/s. It would take a distance of 180 metres to get the same delay (as 7.5 ips) that way. This means that it would be difficult to measure if a signal was recorded twice from both amplifier and microphones in a studio, but on the other hand the delay ought to be too small to be worth that extra procedure. One can but wonder if RCA thought of this in January 1956 when Heartbreak Hotel was recorded - perhaps they found out the hard way when they had to use the stairwell eventually.