AFD100 Marshall Slash Amp Amplifier History

The Marshall SIR #39 is legendary amplifier amp of historical importance. Find out some of the HISTORY behind this amp and where it is now. Is that REALLY #39 pictured below?

Marshall AFD100 Slash Amp History - Will the REAL 'Appetite' SLASH Amp make itself known - A History

This history is updated now and includes part 2 of MisterMiniMite's awesome history lesson. When I was investigating a little history of the SIR #39 amp that was rented for the Appetite for Destruction recordings I came across a great piece of work by MisterMiniMite. That work is duplicated below because I felt it was one of the best stories about the amp I have ever read.

But first.. is this the #39 amp used by Slash for that momentous recording..


Where is it?

There has been much written about the Slash amp and where it is/what it was and the story goes on and on - but is the amp above the elusive S.I.R #39. Check Marshalls site and they say it was most likely a JMP Super Lead or SLII, so maybe this is the holy grail of the Appetite world and a massive piece of history. Note the 'hidden' #39 sound switch on gain 1. Its certainly got some pedigree to it... but we shall see. Maybe its time to rethink where this amp is?

You might well want to visit the AFD100 Forum operated by MisterMiniMite

Now here's the piece from MisterMiniMite


By MisterMiniMite (used with permission)

For many guitarists and rock fans, Slash’s signature sound in 1987′s “Appetite For Destruction” represents the ultimate rock n’ roll guitar tone. From the melodic, neck-pickup-driven opening riff on “Sweet Child O’ Mine” to the action-packed breakdown solo on “Paradise City,” few would disagree that Slash really “hit the sweet spot” in the studio on that particular rig.

But what exactly *was* this rig?

This is the question that has been debated over and over by countless guitarists since the first time the video for “Welcome to the Jungle” aired on MTV. Seeking to replicate that tone, we’ve eagerly read every Slash interview we could find, scoured the internet for clues, and plugged our Les Pauls into every 1980s Marshall we could get our hands on.

But for most of us, it’s been a discouraging and confusing journey, at best. Reports are conflicted and contradictory. Every interview seems to say something different. Was the ’59 Les Paul replica built by MAX or Derrig (no explanation needed for my fellow Slash fanatics)? Was it a Marshall JCM 800, a Silver Jubilee Model 2555 (not likely, since recording for “Appetite” began in August 1986, and the Jubilees weren’t produced until 1987), or something else? Was the amp modified, and if so, how, and by who?

Personally, I’ve always believed that the amp-related questions were the most crucial – and the most intriguing. This is because I believe that the amp used on Slash’s lead/solo parts was probably the one *constant* ingredient throughout all of the songs on “Appetite.” When you listen carefully to every song on “Appetite,” as I have literally hundreds of times, you just might come to the conclusion that Slash didn’t use the Les Paul replica on *all* of his solo parts.

A perfect example is “Nightrain,” arguably a song with solos that epitomize Slash’s “Appetite” tone. To my ear, Slash makes use of tremolo-bar bending a couple of times (listen carefully, and keep an open mind!) during his “Nightrain” lead work (obviously, impossible to do on an ABR-1-and-tailpiece based Les Paul), and the pickups sound a bit hotter than in other songs. Perhaps this other guitar is the “double-locking superstrat” (said to have been a Jackson) that Slash originally brought to the studio for “Appetite.”

(I don’t want to go off on a tangent here, but if you’re still not quite convinced about the tremolo-bar/Jackson argument, listen for the pinch-harmonics “dive” almost exactly one minute into Nightrain. Also, check the inside of the “Appetite” album insert, and see where the band thanks Jackson Guitars (among a practically endless list of other people and companies). Also, keep in mind that Slash had been a major user of tremolo-bar tricks at that time – the first half of “G N’ R Lies” (the live half) is filled with dramatic examples.)

With respect to amps, after exhaustively putting all of the available clues together, and after being given the opportunity to put the question to Slash himself (albeit through a chain of third parties), I have come to the conclusion that Slash used *at least two* Marshall heads to record “Appetite” – a JCM 800, and another, more mysterious, pre-JCM-800 model Marshall – the *one*, true amp that our ears would recognize as Slash’s “Appetite” Marshall.

And that’s where the really interesting stuff begins.


On multiple occasions, primarily through interviews in guitar magazines, Slash has spoken of a Marshall head that he rented from S.I.R. (Studio Instrument Rentals in Los Angeles) and used heavily during the “Appetite” sessions (“Appetite” was recorded between August and December 1986). According to Slash, he loved the amp so much that, when S.I.R. wouldn’t agree to sell it to him, he invented a scheme to essentially “steal” the amp from them. After wrapping up the “Appetite” recordings, Slash told S.I.R. that the amp had been stolen so that he wouldn’t have to return it. Slash kept the amp for a time until a misstep by his roadie at the time spoiled Slash’s plans. During rehearsals at S.I.R. following the “Appetite” sessions (probably sometime in 1987), the roadie made the mistake of bringing the mystery Marshall to S.I.R.. When the guys at S.I.R. recognized their amp, they took it back.

Slash has said that he had a difficult time finding a suitable replacement for this Marshall (while prepping for the “Use Your Illusions” sessions). It is clear that Slash never again exactly replicated his “Appetite” tone, although this might have at least been partially attributable to an intentional evolution of tone on Slash’s part. Slash’s “Illusions” tone stands in stark sonic contrast to his “Appetite” tone, and seems to have been achieved using a JCM 800 exclusively.


To finish the story, we must first step back a year or two to 1985. According to interviews and other reports, during rehearsals for Dokken’s “Under Lock and Key” tour in late 1985, George Lynch was “blown away” by a modified Marshall owned by S.I.R.. Although George had utilized Lee Jackson-modified Marshalls during the actual recording of “Under Lock and Key,” he was so charmed by the modded Marshall, known to S.I.R. as “Stock #39,” that he tried his best to convince S.I.R. to sell it to him. S.I.R. refused to sell the amp (or even tell him who had done the mod), so George paid a substantial sum of money to S.I.R. just for the privilege of renting the amp during the first leg of the tour. The amp was returned to S.I.R. at some point before the conclusion of the tour in September 1986 (probably at least a few months prior to the tour’s end, since George only rented it for the first leg).

Later, despite S.I.R.’s attempts to keep the modifier’s name in the dark, George was able to track down the person who had modified the S.I.R. Marshall and contacted him personally in order to have four of his own Marshalls similarly modified.


Although, admittedly, the evidence is circumstantial, I believe that the George Lynch S.I.R. amp and the Slash S.I.R. amp are one and the same.

As previously stated, George Lynch discovered #39 in late 1985 during rehearsals for Dokken’s “Under Lock and Key” tour. George rented the amp for *only* the *first leg* of this tour (and the *full* tour concluded in September 1986). Guns N’ Roses began recording “Appetite” in August 1986, and the recording was completed in December 1986. This means that Slash probably began renting *his* Marshall from S.I.R. at some time during the Summer of 1986 (August at the very latest, but probably more like June or July). As you can see, there is a virtually seamless timeline here. Following its return to S.I.R. by George Lynch, #39 probably hadn’t been back at S.I.R. for more than a couple of months, at the most (and possibly a much shorter time period), before Slash scooped up his Marshall for “Appetite.”

Given this chronological evidence, what are the chances that George Lynch (who is famous for being particularly picky about his gear and somewhat technical when it comes to his guitar tone, and who had obviously played through his share of custom and modified Marshalls at the time) and Slash (who has said that he usually must try out 50 or more Marshalls before he finds one that is acceptable to him) went bananas over two *separate* Marshalls – *both* owned by, and located at, S.I.R. – and that S.I.R. would refuse to sell *both* of these amps? Neither player was willing to let their amp slip away, and each took extraordinary steps to hold onto it. Although they were both much younger and less experienced at the time, both players’ reactions were so extraordinary and intense that it is probably very reasonable to conclude that they were both head-over-heels about the same amp: Stock #39.

There is at least one more interesting connection between Slash and George Lynch, although it might just be an ironic coincidence. Prior to serving as Slash’s guitar tech, Adam Day – Slash’s trusty right-hand guitar man since 1988 (post-”Appetite”) – worked for – you guessed it – George Lynch.


So exactly what model Marshall was #39? Although records are not perfect with respect to the year that the amp was manufactured, it is known that the amp was a 100W Marshall Super Tremolo (Model 1959T), built sometime between 1965 and 1973. The amp was a hand-wired, pre-master volume model, although it is unclear whether the head was of the “Plexi” variety (’65 through mid-’69) or the later “Metal Panel” variety (mid-’69 through mid-’73, since Marshall replaced hand-wiring with printed circuit boards in mid-’73). The head was modified by a service/repair tech who worked for S.I.R. throughout the 1980s into 1985 (more to come on him later).

In short, the modification consisted of adding an extra pre-amp gain stage. A master-volume control was also part of the modification to #39, since the amp was a pre-master volume model.

The modification made the Marshall very overdriven, essentially leaving it with extremely limited clean-tone (non-distorted) capabilities. This is where the *other* amp previously mentioned – the JCM 800 that has also been connected to the “Appetite” sessions – might fit into the puzzle. I think that the JCM 800 was probably used on all of Slash’s clean guitar parts in “Appetite” (yes, there *were* some clean parts). It is also possible that the JCM 800 was used by Slash on some of “Appetite’s” rhythm parts. However, I believe that it is highly likely that #39 was used by Slash on the vast majority, if not the entirety, of his lead/solo work on “Appetite.”


And the mystery modifier’s name is . . . Tim Caswell. Tim worked at S.I.R.’s tech/service department for several years until 1985, leaving just prior to George Lynch’s rehearsals for the “Under Lock and Key Tour” (which began in late 1985). Following his time at S.I.R., Tim went on to form his company, Studio Electronics, where he remains today. In effect, Studio Electronics grew out of the internal tech/service department at S.I.R., and has moved on to bigger things since that time.

One of the *best* parts of the story of #39 is this: until I contacted Studio Electronics and presented them with all of the information I had gathered, Tim had never connected #39 with Slash and/or “Appetite.” After all, Tim left S.I.R. in 1985, and Slash presumably wouldn’t have rented the “Appetite” Marshall until the Summer of 1986. Although Tim had obviously known about George Lynch’s use of #39 (since George later personally contacted Tim in order to have Tim perform some similar modifications), nobody had ever asked or approached Tim with the Slash-S.I.R. link. After putting all of the clues and bits of information together, and placing them within the context of his personal memories, experience, and knowledge, Tim is now a believer, as I am, that his #39 is likely the primary amp you hear Slash playing on “Appetite.”


Perhaps the most compelling evidence that #39 was, in fact, Slash’s “Appetite” Marshall is this: as of the time that Tim left S.I.R. in 1985 (recall that Slash probably would have initially began renting his Marshall in the Summer of 1986), Tim had been the *one and only* person to ever perform modifications on any of S.I.R.’s amplifiers. It wasn’t until *well after* Tim had left S.I.R. that anyone else performed any modifications on any more of S.I.R.’s amps. Thus, if Slash’s amp had been modified (as is widely believed), Tim would have almost certainly been the one who did it.

Tim recalls that S.I.R. possessed several pre-JCM-800 era Marshalls in its rental inventory. Some of them were 100W Super Leads (non-tremolo Model 1959s); only one was a Super Tremolo. Tim did some relatively standard, mild gain-boost modifications (referred to by Tim as the “stage one” mod) on a few of the Super Leads, but only performed *the* mod – his *signature* mod – on the Super Tremolo (#39). The 1959T and some of the other Marshalls were brought back from the U.K. by Dolph Rhemp, one of the owners of SIR.

Tim got the idea for his unique modification after noticing that S.I.R. had lost the footswitch required to operate the tremolo on the 1959T. One slow day at SIR, he came up with the idea of using the 1959T’s tremolo circuit for hot-rodding the amp.

Tim also recalls that his modded Super Tremolo was, by far and away, S.I.R.’s most exclusive, in-demand, and frequently-requested amplifier, rented primarily to S.I.R.’s higher-profile, celebrity, and discriminating clientele. The amp was used on multiple professional recordings for a number of famous performers. When Tim was at S.I.R., if a high-profile or otherwise important client called S.I.R. to request the company’s best-sounding rock n’ roll amplifier, #39 would have been the automatic, no-doubt-about-it recommendation.

In total, Tim has performed his signature mod on fewer than one dozen amplifiers (all Marshalls). The amps ranged from late ’60s/early ’70s Marshalls through ’80s JCM 800 models. Aside from #39, Tim modified four Marshalls for George Lynch, two for Queensryche, and a few for personal friends of his.


Although it’s been two decades since he modified #39, to my delight, Tim is still available to perform the identical amp mod for customers. The modification can be done on a variety of Marshalls, including, but not limited to, all 1959s, 1959Ts, and JCM 800s (50W or 100W, with or without master volume, hand-wired or PCB) as long as the amp doesn’t have channel switching. In his opinion, the mod works just as well for any of these models. A personal favorite of his is a ’70s Mark II PCB model that he did for his friend Bryan White. SIR #39 was the only 1959T that he ever modified.

Interested parties can contact Tim through his company, Studio Electronics, by visiting the company’s webpage at


I am a firm believer that the abundance of conflicting information and contradictory interviews out there is *not* the result of some sort of conspiracy driven by secrecy or endorsement deals with gear manufacturers. Ultimately, I think that any misstatements have been unintentional, and were made in a good faith effort to answer questions for all of the curious guitarists and fans out there.

First of all, keep in mind that “Appetite” was recorded almost 20 years ago, and that Slash was only 21 years old at the time. Simply stated, memories fade.

Secondly, Slash was, and continues to be, one of those if-it-sounds-good-use-it guitarists when it comes to the amps that he plays through. He’s a guitar collector and a guitar aficionado, but he has admitted that he really is not a “collector” of amps. When Slash was recording “Appetite” with #39, there would have been no need for him to “study” the amp or even take note of the exact model. It is also unlikely that Slash would have even had any particular interest in the technical modifications to #39. He *would* have had an appreciation for the fact that the amp sounded great to him, and that’s probably all that he would have been concerned with at the time. After all, he’s still using his old, reliable ’59 Les Paul replica as his primary recording guitar, simply because it sounds good to him.

Thirdly, I imagine that there might have been a bit of a “falling-out” between Slash and S.I.R. following Slash’s failed attempt at swiping #39 from them. In light of this debacle, Slash probably wouldn’t have been in any realistic position to approach S.I.R. in order to get the specs on the amp, and then go to Tim to have the necessary modifications done.

Fourth, there’s the fact that Tim had already left by the time Slash actually rented #39 to record “Appetite.” Tim’s physical absence from S.I.R. at that time just makes it more unlikely that Slash would have ever come to know who actually modified #39. Besides, as a company in the business of renting out gear, S.I.R. might have been understandably
reluctant to give out Tim’s name, so that anyone who wanted an amp that sounded like #39 would have no choice but to get it from S.I.R. (recall that George Lynch had difficulty convincing S.I.R. to tell him who had modified #39).

Finally, Slash might simply have wanted to move in a new sonic direction, and find a different recording tone, following his “Appetite” days. The fact that he never really tried to *exactly* replicate his “Appetite” guitar tone (by tracking down the specific Marshall model, and locating Tim) might simply be indicative of his intentionally evolving sound. While it is true that Slash has said that he found it difficult to locate a suitable replacement for his “Appetite” Marshall, this does not mean that he wouldn’t have been looking to change his sound anyway for the “Illusions” sessions.


The short answer to this question is: nobody seems to know. Currently, S.I.R. doesn’t carry or rent out any ’65-’73 Marshall Super Tremolo Model 1959T heads, or even own a “Stock #39″ amplifier for that matter. The closest amp that they have now is a non-tremolo 100W Super Lead of the same era. It’s been modified, but the mod was done by another person (*not* Tim) who also modified several other amps in the years following Tim’s departure from S.I.R. in 1985. S.I.R. also carries a couple of old 50W Marshall heads from the ’70s; everything else that they have is JCM 800 and newer.

So what happened to #39? Most likely, the amp was either sold, or rented and never returned, at some point following the “Appetite” sessions.

The amp might still exist out there somewhere. Whether or not it has been further modified or altered is a different story. Maybe the owner knows *exactly* what it is and is keeping the amp locked in a safe. Obviously, there is also a good chance that the amp might never be identified.

So the next time you come across a (presumably beat-up and heavily-gigged by now) modified ’65-’73 Super Tremolo, open up the back of the amp. If it’s signed and dated (in 1985 or earlier) by Tim Caswell, it’s not only the first amp that Tim performed his signature modification on – it very well might be one of the most influential, and mysterious, amps in rock n’ roll history.

Something else I figured I’d include. Here are a couple of related excerpts from some old guitar magazines – interviews with George Lynch and Slash. There are others out there, but here are a couple of really good ones:

(1) Guitar For the Practicing Musician, April 1987 (George Lynch interview):

“For the first album I used old Marshalls, which I’d used for years. Then I tried the Randall's and was happy with them for a while. Then I went to Laney and back to Marshall. I was using Lee Jackson Metaltronics, which is what Vai is using. I also used the Jose modified Marshalls for a while. Now I’m using Tim Caswell modified Marshalls. What happened was that I went into S.I.R. and rented an amp. It sounded amazing. It was the perfect amp. You just plug in and it was all there. I went to the guy and said I’ve got to have this amp. It got to the point where they were calling the owner of S.I.R., who was on vacation, and I was offering him three Marshall heads in trade or $2,000, whatever they wanted. They wouldn’t sell it. They said it was their number one amp. Everybody who came in requested it. I ended up renting it for the whole Twisted Sister tour, which cost me about $2,000. Eventually I had to give it back. I had all kinds of schemes in mind. I thought I’d take all the guts out of the brain and put in different guts. I couldn’t do that. Eventually one of the repairmen told me the guy’s name who did the modification. I called the guy and he did one for me. Now he’s done six for me. He is amazing.”

(2) Guitar Magazine, April 1992 (Slash interview):

“I had one when I did Appetite, which was great. I stole it from S.I.R., and when we were rehearsing at S.I.R. after the record came out, my idiot roadie at the time brought that amp down by mistake, and they took it back. When we went back into the studio a couple years later, I had to find the ultimate amp again…”

Here's the SECOND PART to MisterMiniMite's exceptional work:


By J.R. Rymas

You might recall my article titled “Sweet Marshall O’ Mine?: The Untold Story of S.I.R. Stock #39,” which appeared in Guitar Digest’s June-July 2005 issue. If you don’t, here’s a recap of the pertinent facts:

In late 1985, during rehearsals following the November 1985 release of Dokken’s “Under Lock And Key” album, George Lynch rented a modified Marshall head from S.I.R. (Studio Instrument Rentals in Los Angeles). The amp was a 100W Marshall Super Tremolo (Model 1959T) – a hand-wired, pre-master volume model of the “Metal Panel” (post-”Plexi”) variety (manufactured sometime between mid-’69 and mid-’73). George was so “blown away” by this “perfect amp” (George’s words – not mine) – known to S.I.R. as “Stock #39? – that he desperately tried to convince S.I.R. to sell it to him. After S.I.R. refused to sell #39 or even reveal the name of the person who had modified the amp, George paid approximately $2,000 just to rent the amp for the first leg of Dokken’s tour in early 1986.

Upon returning #39 to S.I.R. following his rental of the amp, George finally learned the name of the mystery modifier who had performed the modification to #39: Tim Caswell (Tim had worked in S.I.R.’s tech/service department for several years until 1985, when he left S.I.R. just prior to George’s rental of #39). Subsequently, George contacted Tim in order to have a handful of his own Marshalls similarly modified.

In short, Tim’s modification to #39 consisted of utilizing the amp’s then-unused tremolo circuit (with its additional pre-amp tube) to hot-rod the Marshall by adding an extra pre-amp gain stage. A master volume control was also part of the modification to #39, since the amp was a pre-master volume model.
Switching gears to another famous guitar player and S.I.R. amp rental customer, my original article stated that, contrary to popular belief, Slash did not use a 1987 Marshall Silver Jubilee model during the recording of “Appetite For Destruction.” In fact, this would have been impossible. “Appetite” was recorded between August and December 1986. The Jubilees were not manufactured and shipped until 1987.

My article went on to document how Slash has also spoken about his affection for a “magic” Marshall head (Slash’s word – not mine) that he rented from S.I.R. and used heavily during the “Appetite” studio recording sessions. After the “Appetite” recordings had concluded, Slash told S.I.R. that the amp had been stolen so that he wouldn’t have to return it. Slash kept the amp for a while until his roadie at the time made the mistake of bringing the amp to rehearsals at S.I.R. following the release of “Appetite” in 1987. When the guys at S.I.R. recognized their amp, they took it back.

My article made the argument that, given the chronological and other circumstantial evidence available (as well as the lack of any substantive and reliable evidence to the contrary), it was reasonable to conclude that the George Lynch S.I.R. Marshall and the Slash S.I.R. Marshall were one and the same.

Since the time of my article’s appearance in Guitar Digest, my research into the topic of Slash’s “Appetite” amp has continued. In fact, the publication of my article gave me the “credibility” I felt that I needed to take my research to the next level. After all, I was no longer just some dude obsessed with gear and “Appetite” – I was some dude obsessed with gear and “Appetite” *who had written an article that had appeared in a magazine.*

Emboldened by my newfound sense of legitimacy, I began a wide-ranging campaign to attempt to track down and contact everyone I could possibly think of who might have even the slightest knowledge about the subject. Through dozens of weekend letters, late-night e-mails, and lunch-time phone calls (most of which receiving no willing repliers), I was able to get in touch with many interesting and knowledgeable people with various potential connections to the subject. However, despite all the fun I had while following up on all of these potential leads,
most of my efforts resulted in dead ends when it came to learning actual historical facts, and I was beginning to get discouraged.

Finally, a *major* breakthrough occurred.

Before I get into this new information, recall the following key excerpt from an April 1987 interview with George Lynch in Guitar For the Practicing Musician (as contained in my original article):
“For the first album I used old Marshalls, which I’d used for years. Then I tried the Randalls and was happy with them for a while. Then I went to Laney and back to Marshall. I was using Lee Jackson Metaltronics, which is what Vai is using. I also used the Jose modified Marshalls for a while. Now I’m using Tim Caswell modified Marshalls. What happened was that I went into S.I.R. and rented an amp. It sounded amazing. It was the perfect amp. You just plug in and it was all there. I went to the guy and said I’ve got to have this amp. It got to the point where they were calling the owner of S.I.R., who was on vacation, and I was offering him three Marshall heads in trade or $2,000, whatever they wanted. They wouldn’t sell it. They said it was their number one amp.
Everybody who came in requested it. I ended up renting it for the whole Twisted Sister tour, which cost me about $2,000. Eventually I had to give it back. I had all kinds of schemes in mind. I thought I’d take all the guts out of the brain and put in different guts. I couldn’t do that. Eventually one of the repairmen told me the guy’s name who did the modification. I called the guy and he did one for me. Now he’s done six for me. He is amazing” Aside from my actual communications with Tim Caswell, this particular George Lynch interview excerpt was probably the single most important piece of information that I had been able to identify early on in my “investigation.” In effect, this April 1987 interview was the original basis for my knowledge of George’s rental of #39.

One sentence, in particular, had always intrigued (and frustrated!) me: “Eventually one of the repairmen told me the guy’s name who did the modification.”

Every time I would read this sentence, it always *killed* me that there seemed to be this one “repairman” at S.I.R. after Tim Caswell left in 1985 who: (1) had this type of detailed knowledge about #39 and who had modified it, and (2) had this level of direct interaction with high-profile players such as George Lynch.
While nobody knew for sure who this “repairman” was that George Lynch had referred to, Tim Caswell and other former S.I.R. guys had mentioned the name of one particular former S.I.R. employee whom they felt might be the only person on earth with the type of knowledge I had been seeking for so long. They universally agreed that this one person would be, hands-down, the key to unlocking the mystery of the Slash “Appetite” amp once and for all.

His name was Glenn Buckley.

The only problem was, nobody had any idea where Glenn was, or how to contact him. In fact, I wasn’t even sure about the exact spelling of Glenn’s first name (was it “Glenn” or “Glen”?), let alone his last name (“Buckley” or possibly the less common “Buckly”)! The last time that Tim Caswell had spoken to Glenn was in 1986. One of the former S.I.R. guys with whom I had been speaking, Jamie Muntner, knew that Glenn had gone on to work at Alesis in Los Angeles after he left S.I.R., but Jamie had lost touch with Glenn after that. I called Alesis, but the bulk of their California operations, including their corporate headquarters, had fairly recently been moved to Rhode Island.

Finally, I found some contact information for a “Glenn Buckley” who seemed to live and work in the greater Los Angeles area, and I called him up. I was *thrilled* to find out that he was the same Glenn Buckley who I had been dying to reach for so many months.

As it turns out, *Glenn* was the mystery S.I.R. “repairman” that George Lynch had referred to in his April 1987 interview!

From early on during my first conversation with Glenn, I quickly learned that Glenn was, without question, the “missing link” and encyclopedic resource that I had been dreaming about. He immediately recalled intricate details about #39 and the other Marshalls in S.I.R.’s rental inventory during the mid-to-late ’80s. Most important of all, Glenn vividly remembered all of the key facts and details about Slash’s “Appetite” S.I.R. amp rental.

Glenn moved to Los Angeles from Vancouver, British Columbia in June 1984 and began working at S.I.R. in September 1984 just weeks prior to his 25th birthday. He worked as the manager of S.I.R.’s quality control department for about five years and left the company in August 1989. Glenn worked closely with Tim Caswell for over a year until Tim left S.I.R. in 1985. In fact, Glenn even recalls how Tim first demonstrated the newly-modded #39 to him in late 1984 (believed to have occurred around December 1984).

As stated above, Glenn was the mystery “repairman” who finally told George Lynch that it was Tim Caswell who had modified #39. Dokken’s “Under Lock And Key” album was released in November 1985. George Lynch and Dokken had been rehearsing in December 1985 for their upcoming tour when George first discovered #39.

Glenn was at the center of the action as George tried in vain to buy #39 and when George eventually settled for renting the amp for the first leg of Dokken’s upcoming tour.
Recent research has revealed that the first leg of Dokken’s tour (which was the U.S.-based portion, with Twisted Sister) began in early January 1986 and concluded with a show in Indianapolis on March 10, 1986. It is believed that George Lynch returned #39 to S.I.R. in mid-March 1986, in the days following the Indianapolis show.

This is when Glenn finally mentioned Tim Caswell’s name to George, and George was able to first make contact with Tim.

Meanwhile, Guns N’ Roses signed with Geffen Records within days of all of this, on March 25, 1986.
Shortly after signing Guns N’ Roses, Geffen paid for Guns N’ Roses to rehearse at S.I.R. during the Spring of 1986 in order to give the band the opportunity to work on their songs before going into the studio to record their debut album.

Glenn recalls reviewing the S.I.R. equipment rental contract for these pre-”Appetite” rehearsal sessions. At the time, Glenn wasn’t familiar with Guns N’ Roses, who were one of many new Los Angeles area bands of the day. Therefore, Glenn didn’t have any basis for anticipating the sound that Slash would have been aiming for with respect to amplifiers. Consequently, at the start of these pre-”Appetite” S.I.R. rehearsals, Glenn brought down a selection of several Marshall heads from S.I.R.’s rental inventory for Slash to try out. Slash’s choice was clear right off the bat: #39. In fact, Glenn is not the only former S.I.R. employee who recalls how Slash insisted on using #39 during these Spring 1986 pre-”Appetite” rehearsals. It is clear that #39 was the only amp in S.I.R.’s rental inventory that would “do it” for Slash at the time.

A few months later, in the Summer of 1986, Glenn recalls reviewing a second S.I.R. equipment rental contract (again, with Geffen Records footing the bill). This second contract called for the long-term rental and delivery of an amp to the studio for the Guns N’ Roses recording sessions (for the album that would become “Appetite”). The contract specifically listed #39 as the amp to be delivered.

Glenn’s heart sank a little bit as he read the contract, since he had just recently rented #39 to another S.I.R. customer, and the amp would be unavailable during the rental time period set forth in the contract. Glenn hadn’t been kept in the loop about when the Guns N’ Roses studio sessions were scheduled to begin. If he had known this information in advance, he might have been able to plan for it by setting the amp aside. In light of the fact that #39 was S.I.R.’s most in-demand amplifier at the time, unless specific arrangements were made clear to Glenn well in advance, Glenn handled requests for the amp on a first come, first served basis.

In any event, S.I.R. still had to deliver an amp, and Glenn soon had a good plan. Although #39 had been S.I.R.’s number one amplifier for almost as long as Glenn had been there, George Lynch’s rental of the amp in early 1986, in particular, served as an important turning point for Glenn and others at S.I.R.. First of all, the intense reaction to #39 by a player of George’s caliber was even further validation of the amp’s special and unique qualities. Secondly, and most significantly, when George rented #39 from early January through mid-March 1986, the amp was sorely missed by S.I.R. and its customers during this fairly longterm absence.

Glenn recognized that S.I.R. simply wasn’t able to meet its customers’ demand with only one amp that sounded the way #39 did. The decision was made to modify a couple of other Marshalls to serve as “substitutes” for #39 for times when the amp was being rented out or routine maintenance was being performed to it.

One of the earliest of these experimental “substitutes” for #39 was Stock #36, which was modified in Spring 1986. The modifications to #36 were performed by Frank Levi (who had just recently been hired by S.I.R. as Tim Caswell’s replacement) in conjunction with Glenn. The two men collaborated on the project, with Frank doing most of the physical modification work.

Frank was very skilled and experienced when it came to all sorts of tube-based gear. When Frank first started work at S.I.R. in Los Angeles, Glenn introduced him to #39. After taking a listen and a look inside #39, Frank was very impressed with Tim Caswell’s work. When Glenn spoke with him about making “more #39s,” Frank was able to make it happen. Frank and Glenn both agreed that #36 was a good test 6 subject to begin their tinkering.

Like #39, #36 was a 100W pre-master volume, “Metal Panel”-era (early ’70s) Marshall. However, while #39 was a Super Tremolo, #36 was a regular (non-tremolo) Super Lead (Model 1959). As such, because #36 didn’t have a tremolo circuit, the amp didn’t have a fourth pre-amp tube as a stock feature. Therefore, when Frank and Glenn applied Tim Caswell’s #39 extra pre-amp gain stage design to #36, an additional (fourth) preamp tube was mounted in a hole drilled next to the original (three) pre-amp tubes.

Frank and Glenn also did some additional tweaking to #36. Specifically, through trial and error experimentation, they switched out certain stock capacitors and replaced them with others obtained from vintage “donor” amps, including some old Fenders, until they were satisfied with the results. As far as other physical and cosmetic characteristics are concerned, Glenn recalls that #36 had the small, “classic” Marshall logo on the front. The amp had “36? stenciled in white, one-inch numbers on each end (whereas two-inch stencils were used on #39). “S.I.R. LA” was stenciled along the top of the back of the amp (also in one-inch letters), with S.I.R.’s phone number below that. The amp was in fairly good condition for its age at the time.

Another interesting variation between #36 and #39 was that the modification to #36 was always “on.” Whereas #39 had a metal toggle switch mounted in place of one of the amp’s four input jacks (which was used to turn Tim Caswell’s mod on and off), the modification to #36 did not include a toggle switch or any other mechanism to turn the mod off. In fact, to someone looking at the outside of #36, the only perceptible modification would have been the addition of a master volume knob. Even this master volume control would only have been noticeable to the trained eye, since it was done in such a manner as to preserve the amp’s otherwise stock appearance.

Anyway, getting back to our story about #39 not being available for the “Appetite” studio recording sessions when the amp was specifically requested in the S.I.R. equipment rental agreement, you’ve probably already surmised that Glenn sent #36 to the studio instead. Thus, #36 was the amp that Slash used during the “Appetite” studio recording sessions.

By all indications, apparently, Slash was just as thrilled with #36 as he had been with #39. In fact, when you read Slash’s relevant interviews, it’s not even clear if Slash realized that #36 (not #39) was sent to him, despite the fact that he had rehearsed with #39, and then specifically ordered #39 for delivery to the studio. Both amps were early ’70s, 100 watt, “Metal Panel”-era Marshalls, with very similar cosmetic characteristics (the tremolo feature on #39 had been plugged and disabled, so from the outside, it resembled a regular Super Lead), and both amps were modified to sound as similar as possible. After S.I.R.’s delivery guys dropped the amp off at the studio, Glenn received no complaints or questions about it, so perhaps Slash never realized that Glenn had, out of necessity, pulled the old switcheroo on him.

At the conclusion of the “Appetite” studio recording sessions, #36 wasn’t returned right away, which wasn’t unusual, since it was pretty normal that some customers would need a little extra time with certain gear for overdubs and other similar reasons. Then more time passed and still #36 hadn’t been returned. Not only did Glenn need #36 back to rent to other S.I.R. customers, but Glenn started to get a bad feeling about his prospects for ever seeing the amp again. After about three months of the amp being overdue for return, Glenn had one of S.I.R.’s dispatchers call about it. At first, S.I.R. was told that Slash was still using #36 and that it would be back within a few weeks. Another month passed and S.I.R. called again. This time S.I.R. was told that the amp had been stolen.

Given the change of story and the preceding stalling tactics, Glenn had a gut feeling that Slash still had the amp. He alerted S.I.R.’s drivers to keep an eye out for #36, since the drivers were constantly all over town, at dozens and dozens of gigs and studios each week. Several months had passed, and still #36 had not been spotted. Glenn decided not to send a bill for cost of the amp to the record company since, in the event that they paid for it and later the amp showed up, Glenn wouldn’t be able to take the amp back.

In the Summer of 1987 (following the release of “Appetite” on July 31, 1987), Glenn got wind that Guns N’ Roses was coming into Stage 6 at S.I.R. to rehearse. [After doing some research into the history of Guns N' Roses in 1987, I believe that these particular rehearsals might have occurred during the first two weeks of August 1987, just prior to Guns N' Roses hitting the road as the opening act for the Cult; the first show with the Cult took place on August 14, 1987 in Halifax, Canada.] Glenn’s hopes rose slightly as he figured that there was at least a chance that he might get some info about what had happened to #36. If, in fact, Slash *did* still have #36, Glenn didn’t think that Slash would ever actually bring the amp to the rehearsals. Nevertheless, Glenn alerted the two S.I.R. guys that worked Stage 6 about the situation, and asked that they call Glenn personally if, by chance, the amp somehow showed up.

During the first days of these rehearsals, Glenn actually went down to Stage 6 himself, standing in the background and hoping to catch a glimpse of #36, but nothing came of it.

A few days later, while Glenn was working late one night, he was informed by the dispatcher on duty that #36 had just been spotted at Stage 6.

The dispatcher, knowing that the #36 issue was personal to Glenn, smiled and handed Glenn the keys to one of S.I.R.’s vans. Glenn asked a couple of the other drivers to come with him to act as witnesses, as well as to provide a little “extra muscle,” if needed. Glenn didn’t know if Guns N’ Roses would be at the stage or not, but it was his intention to walk in, grab #36 “with a smile,” and then simply walk out.

Glenn and the others got in the van and drove the short two blocks down to Stage 6 at Santa Monica Boulevard and Gower Street. They entered through a loading dock door. Glenn went over to the S.I.R. staff at Stage 6 and asked if the band was in. After being informed that that band wasn’t there, without any confrontation or fanfare, Glenn simply walked over to #36 and carried it back to the van, and then drove it back to S.I.R.’s main shop on Sunset Boulevard. Glenn hid the amp for the night in the back of the repair shop under a blanket and some other gear, and then went home, stopping by a local pub, The Cat and Fiddle, in quiet celebration of #36's surprise homecoming.

Glenn never heard a word about Slash’s reaction to #36's repossession, although he never asked anyone about how Slash took the loss of “his” prized “Appetite” amp. Glenn looked after the amp the best he could until the day he left S.I.R. in August 1989. At the time Glenn left S.I.R., both #36 and #39 were still available in S.I.R.’s rental inventory.

Then, of course, came the “Use Your Illusions Sessions” but that is another story (and another amp) altogether!

Thanks and acknowledgement MUST go to MisterMiniMite for this extensive examination of the facts and if you want to know more whizz across to


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