Benjamin Goldwasser

"In addition to the ever-present Fenix (going through OTO Biscuit pedals), Goldwasser also had control of the Roland Chorus Echo delay guitar effect pedal, the Waldorf Microwave, and a rackmount Jupiter."

In this video, Ben can be seen often playing the Prophet 12, perhaps as his main keyboard. e.g 4:55.

At 14:36, whilst he isn't playing it, the camera shows the Big Red '12' showing without a doubt that he's been playing a Prophet 12

In a live performance of "Electric Feel" on KCRW, Benjamin Goldwasser of MGMT is seen using the Access Virus TI2 Polar Synthesizer. Although it seems to have been phased out from his live setup, its distinctive sound likely continues to influence his music through sampling and processing on his Mac Pro.

"But also, older synthesizers such as the Nord Lead and Access Virus—whose older digital converters appeal to Goldwasser—as well as the Roland SH-7 found their way into the circle of gear."

"In addition to the ever-present Fenix (going through OTO Biscuit pedals), Goldwasser also had control of the Roland Chorus Echo delay guitar effect pedal, the Waldorf Microwave, and a rackmount Jupiter."

This image shows Goldwasser playing the Elektron Analog Keys Keyboard

It's plain as day to see that MOOG (pronounced like vogue) Voyager XL being wielded by Goldwasser. It's got a great sound fat, warm, and rich. Great for pads, Bass, and Leads. Goldwasser uses it the right way.

"But also, older synthesizers such as the Nord Lead and Access Virus—whose older digital converters appeal to Goldwasser—as well as the Roland SH-7 found their way into the circle of gear."

The Modor NF-1 is shown at the 4:38 mark of this video

At 0:52 of this video, Ben is seen playing a Wurlitzer 200A for the recording of "Electric Feel".

In the live performance of "Electric Feel" on KCRW, Benjamin Goldwasser of MGMT is seen using the Moog Little Phatty Stage II. Although this synthesizer is featured prominently in this performance, it appears to have been retired from his setup in later shows.

At the 3:54 minute mark of this video the Arturia Micro Brute SE is shown to the left of Benjamin

Kember's aforementioned EMS Synthi A was also much in use. "We ended up using it for the screaming sound on 'Lady Dada's Nightmare',” says Goldwasser. "That was just me staying up on the last night that we were recording in Malibu, right before we packed everything up. I was just making the weirdest noises. He's had some work done on it, a couple of the kind of common modifications. It has a soft sync built in, so you can get the type of oscillator sync sounds the Cars used all the time. But it's like it gets halfway there but it needs to catch up with itself, and sometimes it does and sometimes it doesn't, so it does this kind of throaty thing that sounds like a voice. So that's what that screaming thing is, this weird function of the soft sync.

Goldwasser used an Elka Panther 300 heavily on the MGMT album Congratulations. In this photo from an MGMT practice session, Ben's red Elka Panther can be seen on the far left.

Sound on Sound's article about Congratulations discusses Ben's use of the organ:

Meanwhile, the highly idiosyncratic sound of 'Congratulations' was being created using an array of new musical toys discovered by the band. Chief amongst these was the Elka Panther organ that features throughout. "We found it on Craigslist in LA and got it for about $400,” says Goldwasser. "It needed a little work on it. The vibrato knob's broken but everything else works great. I got really obsessed with transistor organ sounds early on in the recording process. For me it was the most psychedelic sound of the moment. I just love how jarring it is and how cartoony it is. It's this weird reddish orange colour and it's set up differently from some of the other organs. For each register, there's different stops that have a different tone. But then it has a volume knob for the whole stop, so you can set up a tone on one and then you can mix it. It's really musical and you can get so many tones from it really easily.”

Benjamin Goldwasser is confirmed to use the Korg DW-8000, as mentioned in an article by Reverb Machine. The article notes that during a recent Twitter listening party, the band discussed renting a Jupiter-8 and a Korg DW-8000 for the track "She Works Out Too Much," along with employing various obscure Russian Soviet synths and drum machines throughout the album.