In a Gibson interview, Shavo says, "When System of a Down were recording our first record, we went out to buy some equipment. I found this non-reverse body ’66 Thunderbird somewhere in Hollywood. I ended up using it on the entire record. It just felt right. Before that I was using a bass from a different company, and they gave me as many basses as I wanted, in any color I could imagine, but I didn’t like any of them as much as that Thunderbird. Those old Gibsons are the Rolexes and Cadillacs of guitars. They’re all about quality. Just holding that bass made me feel different. You have to fight with it a little to make it your own because it has a heavy headstock that dives to the ground if you let go of the neck. But once I mastered that bass I couldn’t go anywhere else."

Here you can see him playing a WHITE IV BASS

He's seen jamming with it in the video

This photo shows Bassist and Band Lader Armenian So-Cal band System of a Down performing live with a red Ibanez BTB. Ibanez sponsored Shavo Odadjian shortly and in this time he picked up an Ibanez BTB-1000 as well as a BTB-500.

Odadjian can be seen playing a black Fender Precision Bass in this image.

Odadjian can be seen playing a Music Man Stingray in this image.

He started using a Warwick bass in 2017 for their 2017 tour.

Shavo Odadjian of System of a Down is a featured artist of Ashdown Engineering. They have him listed as using their ABM 900 EVO III Bass Amp.

In the Ernie Ball: String Theory video featuring Shavo Odadjian of System Of A Down, Shavo is shown using two Ashdown Engineering ABM 810 8x10 1200 Watt Bass Speaker Cabinets.

In this documentary, at 6:36 and 3:41, shavo is seen with a 1961 stacked knob fender jazz bass in a natural finish. It was used all throughout mezmerize/hypnotize for its sharp attack, and great note clarity for high speed songs. The Gibson Thunderbird, was not used at all for what is on these two albums, due to the tone being much too boomy and not tight, like the fender jazz bass' tone.

Here are some tracks that this bass was used on for further evidence:

https://youtu.be/TVm1OqppOK0

https://youtu.be/k091342VpFk

In a video titled "Shavo Jamming" on his YouTube channel, Shavo Odadjian can be seen with a Rickenbacker 330 Electric Guitar in the background.

In this video, you can see Shavo Odadjian playing this guitar.

In this video you can see an Ampeg SVT-810E Bass Enclosure to the right of the screen at 1:28 seconds into the video behind Shavo

In this video you can see an Ampeg SVT-VR Bass Amp Head at 1:28 seconds into the video behind Shavo

He said he used these strings in the video at 3 minutes

In the second half of Shavo Odadjian's String Theory episode, he's shown playing a Gibson Les Paul Custom while talking about his music wrtiting process.

At the end of this video it shows that Shavo uses regular slinky bass 5 strings and regular slinky electric guitar strings.

he can been seen playing it through out the video

Listed on Shavo's official Ashdown artist page.

In the video titled "Shavo jamming" on YouTube, Shavo Odadjian can be seen with a Fender Telecaster Deluxe in the background.

This bass is seen in the equipment list

Shavo Odadjian is listed as using the Tech 21 SansAmp Bass Driver DI Effects Pedal on Siteofadown, a dedicated System of a Down fan site.

Shavo is seen on stage in the first image on what appears to be like a brown Warwick Fortress Masterman bass.

Shavo Odadjian uses the Gibson Goth Thunderbird IV bass, as listed on Siteofadown's equipment page dedicated to his gear.

In this video taken at the recent Sick New World festival, Shavo can be seen playing a Warwick P/J Streamer.

Used this in 1997. Can be seen being played at The Whisky a Go Go concert.