For the last few months of his time at Sun Records, Elvis Presley pumped his hormonal energy into country, blues, and just about anything else he felt like. With Scotty Moore on the same type of electric hollow-body guitar favored by jazz and country swing players, and Bill Black playing the same upright bass he used on his country gigs, Elvis Presley sang and beat out rhythm guitar on a worn 1943 Martin D-18. During Elvis' Sun tenure, drums and occasionally piano were added to his sound.
But it was Sam Phillips, creating modern record production at the same time Elvis was inventing rock and roll, who gave the band its really big beat, enlarging the group's sound electronically far beyond its three, four, or five instruments, adding echo and using distortion that made the records sound huge and fierce.
For the most part, those revolutionary early discs that set the style for rock and roll would be considered "unplugged" by today's standards. Elvis Presley's guitar style was strictly country rhythm, open chords with ringings strings strummed with a straight pick. Those who say Elvis Presley did nothing more than rip off black bluesmen need look no further than his guitar playing for proof to the contrary. No bluesmen ever played rhythm like that. Black slapped his instrument, rhythmically striking the fingerboard between each pluck of the strings, creating a stuttering percussive effect akin to a snare drum. It was a common comedic technique in the country bands that he'd performed in, often in vaudevillian "rube" costume complete with blacked-out teeth. For his bass to produce maximum slap. Bill Black tuned the E (string) down and let it slap against the neck. Scotty Moore played a bluesy, fingerpicking style drawn from the work of Kentuckian Merle Travis, tossing in some dissonant Memphis blues licks and jazzy chords.
Put all those parts together in Sun's tiny one-room studio, and producer Sam Phillips got an ensemble sound on record much fuller than three pieces had any right to be. The repertoire of those Sun records was just as remarkable as the sound.
Along with the yin-yang of his Delta blues/Kentucky bluegrass first single, Presley crooned "Harbor Lights", "Blue Moon", belted out rhythm and blues "Good Rockin' Tonight", the Roy Brown/Wynomie Harris, and mixed things up even more with western swing//blues "Milkcow Blues Boogie", a straight blues by fellow Sun artist Little Junior Parker "Mystery Train", and even a country polka "Just Because". 
A Memphis musician in the classic W.C. Handy tradition, Elvis Presley was nothing if not versatile, and that would remain the single defining constant in his career, as he drew inspiration from a dizzying array of musical sources.
He haunted the Home Of The Blues record shop on Beale Street, and made Joe Guoghi's Poplar Tunes store his second home and all together turned it into pure Elvis.
Elvis Presley spent part of his vacation at the Sun recording studio. He waxed "Mystery Train" and "I Forgot To Remember To Forget", which would be paired for his fifth and final Sun Records single. "I Forgot To Remember To Forget" would become his first Number One record, reaching the chart in February 1956 on Billboard's National Country Single chart. The song remained on the charts from October 1955 to June 1956, the longest of any of Elvis Presley's single records.
This side, is no less powerful in its own right. For once, Sam Phillips commissioned a first rate piece of original material for his new star. Again, everything works here to perfection: the lyric, the melody, Presley's sexy crooning, Scotty Moore's memorable solo. Perhaps the strongest element is Johnny Bernero's drumming which, more than anything else, defines this recording. Shifting effortlessly from his trademark shuffle to a heavy backbeat during the guitar so elevates this record to greatness.
Composer: - Charlie Feathers-Stanley Kesler
Publisher: - Hi-Lo Music Incorporated
Matrix number: - U-157 SUN - F2WB-8000-NA RCA - Tape Box 1
Recorded: - July 11, 1955
Released: August 1, 1955
First appearance: - Sun Records (S) 78/45rpm standard single SUN 223-B mono
Reissued - 1994 Bear Family Records (CD) 500/200rpm BCD 15801 DI-4-10 mono
"He just didn't dig it at first. Maybe it was a little too country, the chord progression, and it was a slow song, too, recalled Sam Phillips, "but I loved the hook line, and I thought it was something we needed at that point to show a little more diversification. So I called Johnny, he was either in there that day, or I called him, 'cause he had played on some other things for me. And we got it going, and he was doing four-four on the beat, and I said, 'That don't help us worth a shit, Johnny'. I told him, 'What I want you to do is do your rim shot snare on the offbeat, but keep it four-four until we go into the chorus. Then you go in and go with the bass beat at two-four'. And by doing that, it sounds like "I Forgot To Remember To Forget" is twice as fast as it really is. And Elvis really loved it then".
Finally, Sam Phillips had his dream: a two-sided masterpiece by his great white hope, and with both sides owned by his publishing company, Phillips was ready to do battle. This single, Presley's last for Sun, eventually became his first #1 country hit.
Charlie Feathers remember, ''I didn't start the song. Stan Kessler came while we were working on a song 'I Been Deceived' where he played steel on. He had a song called ''You Believe Everyone But Me'' he wanted me to do and then take it up and try to get Elvis do the song.
At that time he mentioned a song he had started ''I Forgot To Remember To Forget''. There was something about that title I liked and said 'Man, that title you mentioned on that song is great.' I went over to his house the next day and we got in there and we played a little and I learned ''You Believe Everyone But Me'' but that song didn't move me too well. So I said, let's get in this thing here, ''I Forgot To Remember To Forget''. We finished it up right there. I put the melody to it and Stan put the biggest part of the words down.
I took it up, but Sam didn't think much of it and it stayed up there two or three months until he finally recorded it and it then turned out to be one of the best things he had done at the time. I was up there when they cut it and Elvis wasn't doing it right. He tried it several times, but Sam didn't think it was right. So we went downtown for lunch, came back and all the time I was sitting there. I'd hum the song, I was humming the song to Elvis and I was showing him that he actually did the song wrong. He was doing the bridge in the song wrong. I got out there and when he came to the bridge I motioned at him, kinda indicated and he did it that way and Sam said "Without a doubt, that's it!" He liked it then and that was it.
It won all kind of awards, it was the number one record at the time. Elvis had never had one in the top ten at that time, so it was his first. Also, ''I Forgot To Remember To Forget'' was the first millionseller, but it was on Sun and RCA combined, you see. They re-released it when he went to RCA because they didn't know how to record him, they thought they had the wrong artist.
''I Forgot To Remember To Forget'' was real big and I've seen a  check down there at Sun records for 2,000 dollars which rightly belonged to Stan Kessler and me. Stan might have got his, 'cause he stayed on there way after me, but I haven't seen one lousy cent yet!''.
According Stan Kesler in 1997, he wrote and produced the song while groping through a painful divorce. Although Charlie Feathers is listed as the co-writer, Kesler made it clear that he alone wrote the song. "Charlie did all the demo tapes and I thought it was only fair to give him the half song.
We had an agreement to pool our talents", Kesler remembered. Since Kesler didn't like to sing, he depended upon Feathers to make the demonstration tape. "I think we worked together pretty well", Kesler noted. "We all knew that Elvis was bigger than the local scene", Kesler concluded, "and it was only a matter of time before he was a star". Part of the magic that facilitated that stardom was provided for Elvis Presley by people like Stanley Kesler. At the July 11 session, Kesler, an accomplished country musician, persuaded Sam Phillips to augment Elvis' sound with a piano, and Frank Tolley, a member of Malcolm Yelvington's Star Rhythm Boys, was brought into the recording studio. Not only did Tolley's piano virtuosity provide a new energy for Elvis Presley's recording, it helped break them into the mainstream country market.
In July 11, 1955, Jack Earls stopped by the Sun studio to watch Presley cut ''Mystery Train'', Phillips originally released the song on Sun by blues singer Junior Parker (SUN 192). Phillips owned the song publishing rights, so he was very interested in seeing Presley record it.
Composer: - Herman Parker Jr.-Sam Phillips
Publisher: - Memphis Music - Hi-Lo Music Incorporated
Matrix number: - None - Take 1 - Tape Box 1
Recorded: - July 11, 1955
Released: - Sun Unissued – Probably Tape Lost
"Train I ride fifteen coaches long...", "Hold it", the beat dies away. "Hey Elvis you got that wrong, should bin 'sixteen coaches'". "Uh, wall I dunno Mr. Phillips, sir, I kinda reckon it was fifteen". The argument goes on, suddenly one of the guys hanging around the studio ones up, "I got the Junior Parker record at home, Mr. Phillips". Sam Phillips leans towards the microphone and booms out his instruction; "Well go get it son, go get it". Jack Earls scampers out of 706 Union Avenue roars round to his house and rushes back with SUN 192, "Mystery Train" by Little Junior's Blue Flames. Perhaps it didn't happen exactly like that, but it is a fact that Jack Earls was at the studio in July 1955, when Elvis was cutting "Mystery Train", and he did go home to get a copy of the record so that Elvis could learn the words. Just one of several contributions made by Jack Earls to the annals of rockabilly music. 6 numbers of coaches in Elvis' song "Mystery Train". Ironically, there were sixteen limousines in Elvis' funeral procession.
After Elvis Presley, Sam Phillips, and Scotty Moore listened to Parker's version, they flipped it over and played the b-side, "Love My Baby". Scotty Moore listened intently to the instrumental virtuously of black guitarist Pat Hare, whose guitar work had more in common with Delta bluesmen than with country musicians.  It took half-adozen attempts before Scotty learned Hare's guitar licks from "Love My Baby". Moore used them on "Mystery Train", a re-combination of elements from the record that transformed Elvis' "Mystery Train" enough to make it popular among both country and rock music fans. Sam Phillips was tickled with the result. Revenge was also a motive for recording "Mystery Train".
"There was an extra bar of rhythm thrown in at one point", said Scotty Moore, "that if I sat down to play it myself right now, I couldn't, but with him singing it felt natural". "It was the greatest thing I ever did on Elvis", said Sam Phillips. "It was a feeling song that so many people had experienced, I mean, it was a big thing, to put a loved one on a train: are they leaving you forever?
Maybe they'll never back. 'Train I ride, sixteen coaches long', you can take it from the inside of the coach, or you can take it from the outside, standing looking in. Junior was going to make it fifty coaches, but I said, no, sixteen coaches is a helluva lot, that sounds like it's coming out of a small town. It was pure rhythm. And at the ens, Elvis was laughing, because he didn't think it was a take, but I'm sorry, it was a fucking masterpiece!".
"I wrote this thing with Junior Parker, but I really think "Mystery Train" is my personal Elvis Sun track", recalled Sam Phillips. "It's one of the most simple songs in the world, it's one of the greatest vamp beats. This was done, and the take that we used... if you'll notice on the end of that thing you'll hear Elvis laughin' cause he didn't think we had a take and he was laughin' at the end of it. He thought, hell, he'd screwed it up, and it's just fantastic. It's an incredible take to me".
On "Mystery Train", all you have is quintessential rockabilly: a confident, virile vocal, staccato revert lead guitar, audible rhythmic guitar strumming by Elvis Presley, and driving percussive bass. If anyone ever asks you what a slap bass sounds like, just play them this record. There is not much room for improvement here. Even the abortive fadeout, during which Elvis' "Wooooo" disintegrates into unselfconscious laughter, seems part of the magic. The distance between this track and Little Junior Parker's original (SUN 192) is immense, from the telling lyrical change (Parker's "It's gonna do it again" is transformed by Presley into "It never will again") to the tempo change from a sluggish freight to a runaway locomotive.
Both Junior Parker's 1953 original of "Mystery Train" and Elvis' astonishing rethink are perfect in their way. Like "Unchained Melody" and "Come Softly To Me", the title is mentioned nowhere in the song, compounding the enigma. Elvis Presley sets a tempo closer to "Love My Baby", the flip side of Junior's single. As he breaks up near the end, he is clearly thinking that this was a rehearsal. Sam Phillips knew better. "The greatest thing I ever did on Elvis", Sam Phillips insisted. No argument.
"MYSTERY TRAIN" - B.M.I. - 2:25
Composer: - Herman Parker Jr.-Sam Phillips
Publisher: - Memphis Music - Hi-Lo Music Incorporated
Matrix number: - U-156 SUN - F2WB-8001 RCA - Take 2 - Tape Box 1
Recorded: - July 11, 1955
Released: - U-156 August 1, 1955
First appearance: - Sun Records (S) 78/45rpm standard single SUN 223-A mono
Reissued - 1994 Bear Family Records (CD) 500/200rpm BCD 15801 DI-4-9 mono
In 1989, Elvis Presley is everywhere in the film "Mystery Train", directed by Jim Jarmush, of three separate but interlocking vignettes. A Japanese couple visit Graceland and Sun Studios, Elvis' ghost is seen, a sleazy hustler tries to sell an Italian widow what he says is Elvis' comb, every room in the Arcade Hotel, located at 540 South Main Street, has a portrait of Elvis Presley, and two Elvis songs are heard: "Mystery Train" and "Blue Moon".
''Mystery Train'' did not make pop charts. What's scary about the young Elvis Presley is his assurance, the complete ease with which he swings into action. Here, singing a song in which rhythm and blues singer Junior Parker reworked the folk images from country songs like the Carter Family's "Worried Man Blues", Elvis rides an urgent Scotty Moore guitar lick and propulsive Bill Black bass line with complete confidence: He owns the song and nothing within it is unknowable to him or could ever betray him. Which is pretty weird because he's singing about something close to a death ship, a "long black train got my baby and gone", which may also be looking to snatch him. By the end, he's persuaded himself - and you, too - that it's bringing her back.
The recording itself is a masterpiece, the sound virtually liquid as it hits the car, the legendary Sun echo finetuned like a Ferrari. Junior Parker's version, a minor rhythm and blues hit in 1953, is spooky because it details what fate can do to a man. Elvis makes you want to defy all omens, he to the graveyard and dance fearlessly at midnight.
Name (Or. No. Of Instruments)
Elvis Presley - Vocal and Acoustic Rhythm Guitar (Martin Dreadnought 18)
Scotty Moore - Electric Lead Guitar (Gibson ES 295)
Bill Black - Acoustic Upright Bass (Kay Maestro M-1)
Johnny Bernero - Drums (Gretsch Round Badge Kit)
Probably Doug Poindexter - Acoustic Rhythm Guitar
Within days of the session Sam Phillips had shipped the tape off to be mastered by Bill Putnam at Universal Recording in Chicago with the words, ''Give me ''hot'' lever on both 78 and 45s and as much presence peak and bass as possible!'' written boldly on the Scotch Magnetic Tape box. There were two noteworthy aspects to this transaction. One was that up until now he had done all of his mastering himself, on his own Presto lathe. The other was that he should be willing to trust anyone to bring out the sound in what he recorded, given how much he knew you could lose in the mastering process. But this was Bill Putnam, universally acknowledged as the progenitor of modern studio recording and one of Sam Phillips' true heroes in the business. Bill Putnam not only had the kind of equipment that was needed to get the levels that Sam wanted for this record, Bill Putnam had the kind of ''feel'' necessary to bring out the excitement he felt.