Indian music and the blues tradition; he developed a precise playing style and sound that partly evoked the fretless Indian sarod. From its introduction on All Things Must Pass, Leng writes, Harrison's slide guitar became his musical signature – "as instantly recognisable as Dylan's harmonica or Stevie Wonder's". Final mixing and mastering On 9 October, while carrying out final mixing at EMI, Harrison presented Lennon with the recently recorded "It's Johnny's Birthday". The track featured Harrison on vocals, harmonium and all other instruments, and vocal contributions from Mal Evans and assistant engineer Eddie Klein. That same month, Harrison finished his production work on Starr's 1971 single "It Don't Come Easy", the basic track for which they had recorded with Voormann in March at Trident. Aside from his contributions to projects by Starr, Clapton, Preston and Ashton during 1970, over the following year Harrison would reciprocate the help that his fellow musicians on All Things Must Pass had given him by contributing to albums by Whitlock, Wright, Badfinger and Keys. On 28 October, Harrison and Boyd arrived in New York, where he and Spector carried out final preparation for the album's release, such as sequencing. Harrison harboured doubts about whether all the songs they had finished were worthy of inclusion. Allan Steckler, Apple Records' US manager, was "stunned" by the quality of the material and assured Harrison that he should issue all the songs. Spector's signature production style gave All Things Must Pass a heavy, reverb-oriented sound, which Harrison came to regret. Whitlock says that, typical of Spector's Wall of Sound, there was some reverb on the original recordings but the effect was mostly added later. In music journalist David Cavanagh's description, once abandoned by his co-producer midway through the summer, Harrison had "proceeded to out-Spector Spector" through the addition of further echo and multiple overdubs. Voormann has said that Harrison "cluttered" the album's sound in this way, and "admitted later that he put too much stuff on top". According to Leckie, however, the reverb on tracks such as "My Sweet Lord" and "Wah-Wah" was recorded onto tape at the time, because Spector insisted on hearing the effects in place as they worked on the tracks. Outtakes from the recording sessions became available on bootlegs in the 1990s. One such unofficial release, the three-disc The Making of All Things Must Pass, contains multiple takes of some of the songs on the