The Master of Puppets album was a high water mark for heavy metal. It redefined the thrash metal sub-genre and is still often cited - nearly 40 years later - on numerous Top 100 album lists.
In this Gear Spotlight, we’ll discuss a critical component of the landmark and coveted guitar tones on the album - the Marshall cabs used during tracking.
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THE HISTORY
In the fall of 1985, Metallica entered Sweet Silence Studios in Copenhagen, Denmark to record their second album with producer Flemming Rasmussen. Over the course of 4 months from September to December, Metallica tracked what many critics consider their finest album - Master of Puppets.
As guitar tracking commenced, James Hetfield and Kirk Hammett used newly acquired amps - (3) Mesa Boogie Mark IIC+ and (1) Mesa Boogie Mark IIC++ head units. James and Kirk each acquired 1 new amp with 1 as a backup with gear advances provided to purchase new equipment. James used his primary Mark IIC+ then dubbed as “Crunchberries,” while Kirk’s primary amp - the only Mark IIC++ in the possession of the band at that time, often called “Lead A” - was used during tracking of his leads. These heads sat side-by-side in the studio on a pair of Marshall cabs.
The Marshall Cabs on Master of Puppets
Numerous cabs were available at any given time in the studio, and multiple combinations of cabs were tried to achieve the desired tone. When it was time to track guitars, 2 primary cabs were chosen. These cabs were a pair of June-July 1985 Marshall JCM 800 4X12 “B” cabs with vented Celestion G12T-75 speakers. Let’s explore the information surrounding the cabs and how we reached that conclusion.
When Flemming released studio notes from tracking of the album, some notable details stood out in the identification of the cabs used - the serial numbers and wattage of the cabs - which were serial numbers 11622 and 11739 with both noted as 300W.

This becomes notable for numerous reasons. Pictures of the cabs clearly indicated that JCM 800 era straight “B” cabs were used, but the JCM 800 front badge alone isn’t sufficient for identification. Marshall used the same front badge for cabs during this era spanning countless speakers. However, when combined with the serial numbers and wattage, we can not only identify the cabs, but narrow the cabs down to a small window of time in Marshall’s production range.
The JCM 800 “B” cabs kept a consistent serial number format for the primary line throughout most of the 1980s. Given the serial scheme used on the MoP cabs, this allows us to rule out the adjacent speaker cabs using similar front badges (e.g., G12-100, etc) and focus exclusively on the primary line. Now that we’ve determined which series of cab these are in, let’s dig deeper to determine the timeframe they were manufactured in and the speakers used.
The Master of Puppets Speakers
Marshall had been using the Celestion G12-65 speaker for a number of years going into the early-to-mid 1980s, but - as companies often do - decided to “improve” upon that offering.
By 1983, the G12M-70 speaker was introduced into the mainline cabs, but quickly removed. Many myths persist on why it was short-lived. “User feedback” was terrible, “folks at Celestion weren’t happy” and numerous other stories surround them. What is the truth? It’s all subjective. Asking 3 former employees at Celestion will likely net 3 different explanations. Regardless of reasoning, they didn’t last long, mostly appearing in cabs no later than early 1984.
By late 1983, Celestion was quick to course correct and introduced a new speaker - the vented Celestion G12T-75.

Many online sources report this speaker was not introduced until 1984 or 1985 (including some official Celestion articles), but this is inaccurate. Speakers of this type have been seen with date codes as early as October 1983, although these are relatively rare. Marshall seemed to finish out the remaining stock of G12M-70 speakers mixed with the G12T-75 going into 1984. If you own a mainline production Marshall cab from late 1983 through early 1984 with original speakers, you’d likely have to open it up to see exactly what speakers came with your specific cab.
The early G12T-75 speaker is subject to much debate. There is a possibility that the only noteworthy difference between late era G12-65s and early era G12T-75s is a Kapton voice coil used on the 75s as opposed to the fibreglass voice coil used on the 65s. It’s entirely possible that in Marshall’s haste to replace the 70, a different coil was used on the 65 with a new label slapped on it to brand it as a “different” speaker. Even that single change, however, lent a different flavor to the tone and allowed the 75 to inherit an additional 10W of power handling.
Narrowing Down Production Dates
With the series of cab now determined, the serial numbers allow us to narrow down the production date significantly. Marshall, like many manufacturers at the time, was very frugal and cost conscious. When the transition to the G12T-75 speakers came, Marshall continued to use the older 260W serial number plates that were produced for the G12-65 to finish using their remaining inventory. Because of this, most early G12T-75 loaded cabs from Marshall were erroneously labeled as 260W as opposed to 300W. This led to confusion at times, including leading players to wrongly assume their cabs came stock with Celestion G12-65s.

The example seen above is from a late 1984 Marshall JCM 800 4X12 “B” cab with stock vented G12T-75 speakers. Marshall did not start using the newer 300W serial badges consistently until early 1985.
Given that B cabs from the primary series started 1985 in approximately the 10500 serial range in January, and just under 2000 cabs were produced by October 1985, we can narrow down the production date of the cabs used on MoP. With the assumption of equitable production across months, this would place the production of the MoP cabs roughly in the June to July 1985 timeframe.
Putting it all together, this means the cabs used on Master of Puppets were a pair of June-July 1985 Marshall JCM 800 4X12 “B” Cabs loaded with vented Celestion G12T-75 speakers. Of particular note here is that the band went into the studio to record the album in September 1985. With a June-July production date, it indicates the cabs were virtually brand new at the time, being barely 2-3 months old when the band entered the studio.
A Buyer’s Guide for “Master of Puppet” Cabs
If you’re looking to purchase a cab for Master of Puppets type tones, what should you buy?
Option 1: Buy an Original
If you’re looking to get as period accurate as possible, a mid-‘80s Marshall JCM 800 4X12 “B” cab with vented Celestion G12T-75 is the closest you’ll find. Buying a standard series JCM
800 1960B cab in the 10500 - 12500 serial number range places the cab close to the same production run as the cabs on MoP. Please note this serial number scheme refers only to the “B” cabs. The “A” cabs follow a different serial scheme.
Option 2: Buy an Original “Adjacent”
If you’re not able to find an original with vented G12T-75s, you could seek out adjacent cabs that came before or after. Slightly earlier cabs with Celestion G12-65 speakers are similar. While not exact, some subtle EQ will get you into the ballpark and give you a cab manufactured close in era. Another adjacent option is buying the slightly later G12T-75 loaded cabs with non-vented versions of the speakers.

The non-vented versions - on average - seem to have a slightly more present midrange with a touch of additional rolled off top end. These non-vented white label speakers were made through the late 1980s until 1989, with some scattered into early 1990.
Option 3: Modern Celestion G12T-75 Cabs
If you cannot find an older model cab or are looking for a more affordable option, any later edition Marshall G12T-75 loaded cab will suffice. The 1990s era Marshall JCM 900 cabs (4X12s and 2X12s) can be found for very affordable prices, and all were loaded with UK made speakers (as opposed to China starting in the early 2000s). While the speakers underwent some tonal change, many of these cabs now have 30+ years of break-in which helps tame some highs and round out the low end.
Buying Disclaimers
When buying vintage cabs and speakers, it’s important to highlight a few important notes.
First, used cabs of this age have been around for 30-40+ years. Just because it came stock with a particular speaker doesn’t mean that it still has the stock speakers in it. A best practice is always ask what speakers are in a vintage cab and get assurances from a seller to the best of their knowledge that the speakers have no issues. Get pics if possible. It’s always a risk buying vintage gear, but asking smart and targeted questions can help ensure that you have an understanding of what you’re purchasing.
Second, no two vintage cabs and speakers will sound the same. Aside from different parts and batches differentiating them when new, 40+ years of varying levels of break-in, storage, and aging will cause drastically different swings in the tone not only from cab to cab, but also from speaker to speaker within the same cab. No two you purchase will sound identical, so buying vintage can become a slippery slope if you’re looking for something with a specific sound.
Third, the cabs themselves vary in sound and tone as much as the speakers themselves.

I’ve owned quite a few of these cabs and vented Celestion G12T-75 speakers over time. I still own 4 of them, with a pair of them pictured above - a 1984 cab and a 1985 cab made only a few hundred serial numbers off from the MoP cabs.
They all sound different. Some are brighter and some have more low end, while others have more or less mids. One particular ‘84 cab of mine makes everything that’s in it sound appreciably brighter and more scooped, even when using the same wiring and speakers from another cab that sounded darker and mid heavy!
The moral of the story here is you never know how a vintage cab or speaker is going to sound until you try it, and it’s highly likely that very few will sound exactly the same. As long as you approach buying vintage with an open mind and realistic expectations, you should be able to find something that suits you, your rig, and the tone you’re trying to achieve.
If there are aspects of the Marshall cabs not covered here that you’re curious about, please leave a comment or send a message. We can edit the article to include additional information if there is a demand for it.
Also, please check out our other articles for a detailed analysis on other Metallica gear, album breakdowns, and more. Thanks for reading!
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