Marshall YJM100 Yngwie Malmsteen Amplifier Deep Review by Tony Mckenzie

Probably the longest review of this amp anywhere in the world!

Firstly, I really want you to remember that I only mention things that do matter in my opinion in one way or another in this review. Remember that as you skip past things that might appear to be filler for the review. Nothing is filler. Its important to gain knowledge from this review – that’s why its here!

Secondly, this review has been read by Santiago Alvarez, chief designer at Marshall Amplification PLC. Santiago kindly commented on a number of things which I have included inyellow – and any replies from myself in green.

Remember that those comments in colour were added after my review – hindsight sometimes is a great thing…

Heres the review of the YJM100 amp and note that at the end of the review is my latest update.


After the AFD100 amp from Marshall this is I guess the second most awaited amp in recent times. Its a behemoth of a product (just as the price is) but should come through with the goods now that Marshall has released this amp – even though they are currently coming from the Marshall factory in the UK slower than a snail in winter. This will change over time.

This amp offers some unique features over and above the AFD100 amp, but is it really worth the difference in money for the YJM100 amp?

This YJM100 is getting an even more in depth review than the Slash amp ever did… why, well if you have heard of Yngwie J Malmsteen, or better still seen him play and or heard the music then you will know that this amp is one of the most used and driven amp ever to hit this sunny land of the UK or anywhere else… and when it (if it) gets to the USA you guys had better be prepared… ‘Yng’ rules.

Yngwie takes absolutely no prisoners at all and if you are a ‘Yng’ clone good for you.. but really that’s what you will remain, a clone of the real deal. One of the reasons why I don’t typically play other peoples music…. I don’t want to be a copy of some other guy who got his stuff together instead of copying someone else.. if you get what I mean… you might think about that in what you do with your music… ever heard of someone who copies a well known musician getting to make real money in the music business? of course not…

There’s a lot on offer in this amp, the power reduction like on the AFD100, the 50/100 watts switch, the noise gate, the overdrive built right in to the amplifier and more, all boxed up to look like something from the very late 60’s or early 70’s. A very nice RED cover supplied too.

Whereas the AFD100 had a reasonably undefined era case, this YJM100 is exactly a specifically defined era case, so whether you like it or not, using one of these YJM amps is going to define you (at least that’s what your audience will think) as a tone hound. FYI a tone hound is one of those guys always looking for ‘that’ tone but never actually finds it (it’s not there to find and is a figment of the tone hounds mind) – and there is only one Malmsteen.

Actually this amp was not for the world to find out about yet… but someone let it slip out… so Marshall told the world in January NAMM 2011. And why not I say, we waited long enough for the AFD, so why not wait for this too? I’m actually getting used to it!


The Marshall YJM100 arrived with me on the 28th July 2011 and I’m told its one of the first 25 units released (but who can believe that – they are all dealers selling things) – apparently these are coming out of the Marshall factory here in sunny England slower than the time it took to write this site (and that was a very long time).

But don’t despair – the YJM100 for review is here now – and don’t forget to visit my YouTube channel at to see the videos – one inside the amp and one showing the tones.

This review covers inside and outside of the amp, a thorough check of exactly what you get, analysis and comparisons between this and other amps, and lastly some video of the sounds.


Just messing around after first switch on…

But don’t forget that I’m no Malmsteen and never will be – and more likely than not – you are not either. But this amp is far more than just a ‘Yngwie Malmsteen’ amp so to see it in other modes or styles than ‘Yng’ plays should be a very useful thing – especially if YOU are no ‘Yng’ either. And if you ARE an ‘Yngwie’ – nice (I think he is awesome), I always wanted to do that but was told ‘not to try this at home’ so I didn’t. If you can play as Malmsteen you must have been misled at some stage in your life 🙂

Or maybe you grew up on a forum…. they are all the greatest everything… and the best thing to do about that…

is to stay there and hide behind some really pathetic name.



 I had ordered this amp some months earlier on the basis that if it’s good enough for Yngwie J Malmsteen, then its good enough for me! (Yngwie is pronounced ‘ingvay’ – I just thought I should say that in case you wander in to a shop or something and say the wrong thing 🙂 – don’t worry – I did too once!

In case you did not know, Yngwie is a top class metal guitarist who started (in my opinion) the whole neoclassical style of rock lead guitar playing.


Yngwie J Malmsteen – Marching Out

I went out and bought that first album and could not believe what I was hearing. Here was a European guy who had simply changed rock guitar forever and he did it on that one album, right there and then. He did not stay in Europe for long.

Some of those tracks today are just as awesome and inspiring as they ever were. In fact I played the whole album last night and instantly remember why I play guitar.

But its like anything really, ‘Yng’ (as we shall call him for this review) is older and some say he has mellowed a little – a ‘nicer’ Yng. Let’s hope that he has, I once met him in ‘Musical Exchanges’ in Birmingham England and he was extremely aggressive and did not have the time of day for his audience at that time. Gary (yes you Gary at PMT Birmingham UK) calmed Yng down a little and the result was that I did get a signature. Good old Yng…

Later down the road, I thought some of the music deteriorated a little from that spark that was on the original albums I heard. And some of those later albums I really did have a hard time with, the playing is there but the content seemed to slide away somehow from that original awesome playing on the first two or three albums. But its great that Yng is still alive and playing as great as ever. Yng has in my view picked up again more recently.

Yngwie always used Marshall amps to play through. I did hear rather a lot about Yng’s amps and guitars (lord knows he has enough) but I was always led to believe that Yng always used 50 watt Marshall heads without reverb, front ended with a distortion pedal. Maybe you heard the same? Maybe not?



So Marshall Amplification have a long chat with Yngwie J Malmsteen and lo and behold here comes the YJM100 – A tribute to Yng by Marshall. What a great idea – sounds like the Slash AFD100 a little, buy Yng is no Slash. And that’s a fact – those two are as far apart as you can get.

But anyhow, the story is a little twisted (like me) and the specifications for the amp take on a new twist, Marshall and Yng decide to make a ‘Plexi’ copy, integrate digital reverb, include Yng’s distortion pedal (thank you DOD) and throw in a noise gate too. They also make the amp switchable from 100w to 50w and include the same Power Reduction system which was first sold under the AFD100 amp model – reminiscent of a London Power design.

That’s fantastic… but is it REALLY the amp that Yng has used for all these years?

If you believe what is published then Yng these days says that he always used 100w AND 50w heads together (louderama) AND reverb depending on the venue. Where the hell did I get that 50w head only stuff idea? Maybe it was from the devil himself I don’t know, or maybe Yng was not telling the truth all along… only Yng says the 100w was always there with the 50w tagging along for the ride… but just maybe he did use 50w Marshall’s and no reverb!

In any case, both Yng and Marshall Amplification are telling the same tale today. It could really be that way, or it might not be. But I distinctly remember seeing Yng (I was 10 foot from him at the time) playing through a Marshall 50w head (with no reverb) in Birmingham at that time all those years ago.

Like most things, its really a question of what is myth and what is fact… and somewhere between the two will lie the actuality of it all. Sounds like the AFD100 sort of vibe? maybe, but no matter what, some will argue and discuss this aspect of both the AFD100 AND the YJM100 for years to come. I have already made my mind up.




The YJM100 Marshall Amp set up and ready to rock – or is it?

Take a good look at the design, its sort of a Plexi style amp – if you look at it face on from the front it IS a Plexi amp – just those three letters ‘YJM’ on the left face of the amp tell us its not. So it all looks cool?

Well not quite. Looking at the amp from either end and you will immediately notice that this amp is fatter than the ‘Plexi’ of years gone by – maybe Marshall should have called it the ‘Fat Boy’? Its also far fatter than the reissues that Marshall still incessantly make of the old ‘Plexi’ from the 70’s.


Side View of the YJM100

This image of the rear of the amp shows clearly just how wide the YJM100 actually is when it is sitting on top of a Marshall 1960B cab (those are the wide square ones at the bottom of a stack) and just how much real estate is taken up by the amp.

Marshall say that the YJM100 housing is the same as a Marshall Major (which was a 200 watt amp) and I believe them. Trust me on this it IS big.

Its heavy too – this amplifier comes in at a whopping 24Kg (about 50 Lbs.) and while that is not a record, it makes little difference as you crack your back. Indeed the shipping box specifically says its a two man lift. So why one handle? Those aesthetics have a lot to blame.

They say (as I pointed out above) that Yng needs one for 100w and one for 50w to get those tones. Actually, knowing Yng (at least as I perceive him) he needs 25 of each!

But ordinary guys are not going to do that are we? Of course not.

Actually I don’t know a single guy that would buy two and use one 50w and the other 100w.. all stacked up on 4 4×12 cabs – its a little hard to grasp that someone you know will use two either. Neither the real estate or the backbreaking weight is going to let you? is it? Don’t even mention the cost! Maybe you’re a Yng clone… so maybe you want two? I’m sure that somewhere in cloud cuckoo land on the forums there will be a few that claim that’s their setup and they are playing the arena’s ‘sometime’ soon.

Then there’s those pesky knobs on the rear of the unit – put there in my opinion for aesthetics so that the amp from the front remains faithful to the Plexi of years gone by. A good idea –unless you want to change the settings. There is no doubt you will. Maybe you will have the back of the amp facing you and the front away from the audience? Then why bother making the front of the amp so ’70’s’… that does not work either. Hopefully its a set and forget for those knobs on the back – and that’s exactly how I found them once I got to really ‘know’ the YJM100 amp.

But actually it is good to see that this amp at least from the front looks right and I still think that was the right choice.

Yng and friend (did I really say that) did put some thought in to those aesthetics (how it looks if you don’t know what the word means 🙂 and the fonts etc. are (as far as I can tell) correct. Unlike the AFD on this amp you can read them!

It looks good.




Manuals and other goodies in the box

Like most Marshall stuff there’s a nice manual, and in this case its one with pages of Yngwie chat. Interesting, but it’s not going to help… if you are not a Yngwie clone – you will probably be like that for life.

There’s also the usual welcome from Jim Marshall. Its good to know that Jim is still around although I doubt he has much input really these days. After all, Jim has been around a long time. Great to see some input anyway attributed to Jim and even greater if he actually wrote it!

There are also two or three pages explaining the features of the amp. Its not rocket science and is quite a good manual but it’s a bit short. I would have liked to see some Yngwie ‘settings’ in there just for posterity… then we could all see exactly how Yng gets those sounds from this new amp.

Also included is the EU safety and other regulatory docs – binerama, and a YJM100 ‘certificate’ which if the truth be known, is simply a printed A4 document with probably zillions printed off. Worthless in my view – those Yng ‘settings’ would have been a much better option. In fact, Yng could have written a page or two (rather than the sell speak) about his exact settings with this amp – a substantially better contribution than the certificate. But don’t worry… they didn’t do it.

More importantly is a build sheet included. This shows who and what built and checked the amp and the dates they did it. I’m looking for one of those dudes (but read on it all becomes clearer later down the road).

Lastly is that fantastic Ferrari red (can I say that? oops I did) amp cover with the Yngwie YJM100 logo and other nice things such as facsimile signatures of Jim Marshall and Yng himself.

Spiffing (no, really) I really like that amp cover… it makes the amp look cool and really adds to the overall feel of this amp being a little different.



The serial number on the one I received was:


The serial number on the YJM100 amp I received

In fact the code is: year – week – sequential number – voltage/area code as confirmed by Santiago Alvarez from the AFD100 review on this website.

So this makes the amp I received a 2011, week 27 (July) amp (see what did I tell you) and area one (UK).

Investigation inside the amp showed the PCB as 04/2011 and the main board as issue C.

So this unit, by the time they got all the bits together was shipped out pretty much a week or so before I received it.

But one thing was actually very annoying. Its to do with the supply of the amps to the dealers. I continually chased the delivery of my ordered amp with my dealer (Academy of Sound) a dealer I trust greatly and in fact believe what he said about my order.

The story goes that these amps have been shipping for a short while at a very slow pace. I spoke with my dealer about a week before getting this amp (sounds like a drug thing) and he said that they were still hardly coming out of the factory. I asked other contacts and they ‘were not allowed’ to tell me dealers who had taken delivery of the YJM100! I still can’t follow that line of thought no matter how hard I try. But I don’t blame the contact – its just a ‘PLC’ mode they get in to. But customers should come first.

So I went fishing to see if there were any on the internet.

There were! I found a single dealer with TWO actually in stock and ready to go. So the next day I called up my dealer (again) and confirmed I needed the amp now so I could review it (what a ridiculous situation to be in). The dealer went off to the Marshall rep… as they do and promptly called me back. The good news was, that ‘maybe’ we will have yours in a week or so… but we cannot tell you for a week if that will or will not happen.

In the end I had to cancel with my regular dealer (no fault of his) and buy one of the two on the net. Asking carefully about allocations of the YJM100 with the new dealer, he confirmed that they had now received FOUR of these amps. My dealer on the other hand received nothing without any firm promise of delivery to him from Marshall. Ouch. That’s just plain wrong.

Its really up to Marshall and other companies how they distribute their products and its none of my business. That is, until I can’t get information where to buy one now, AND that my dealer is messed about with my order by the supplier with ‘ifs or buts’. That little ditty cost my dealer the business and believe it or not I have great sympathy for that dealer. I HATE buying amps from people I don’t really know and I do have loyalty to my trustworthy regular dealer. If only… it’s tough enough for dealers without being messed about.

Thanks Marshall for that one.

And if you think Marshall is bad wait until I tell you about the product I’m reviewing next – absolutely unbelieveably bad – and that product for review certainly never will be a Marshall product. Later….



At first I had a feeling of dejavu with this amp. The fixing pins for the back cover are in fact EXACTLY the same as the AFD100, machine screws, short and mounted in to metal fixings in the wood. At least there is conformity to a standard… even if the older Plexi had wood screws, but I guess there is only so far they want to take that ‘look’.

Note though that the corners of this amp have no plastic covers to protect them and might get some knocks on the road, as indeed the original ‘Plexi’ amps confirm.



The chassis is 1.6mm steel as confirmed by Santiago Alvarez when I reviewed the AFD100. It might have changed a little (its a bigger unit remember), but it looked identical to me… and it might indeed look that way to you too.


Chassis thickness

No matter how you look at the Marshall chassis its made well. There’s absolutely no getting away from that.



Once again (just like the AFD100 which claimed to be also from a different era) the YJM100 board was a modern, computer developed board – and it showed. The quality of the board was excellent with no hard wired modifications or fixes as is so common these days from some manufacturers. These usually show themselves as point to point wires (usually singular) that ‘fix’ PCB design issues. Those issues are later ‘fixed’ on newer issue or revision boards.

I noticed on this amp that the PCB in question was an issue ‘C’:


Issue C Board

Now Marshall may use the ‘issue’ for other things. It does not really matter except to say that the board is not the first one they developed. AND that there are no hard wire ‘fixes’. Its good to know and frankly gives me some confidence at this point on the review.

Let’s take a closer look at inside the amp (click it for a larger image):


YJM100 Chassis Layout

Exactly as Santiago Alvarez said, The YJM100 has the same transformers that the AFD100 had. Here’s what Santiago said “Output transformers are the same as the 1959’s and the JCM800’s but mounted horizontally. We used the same transformers in the JVM, 2203KK and YJM100 for example. The mains transformers are a variation of the JVM ones, which are beefier than the JCM800 ones for example.  Indeed, there are many similarities.

It looks like most of the Power regulation is the same or very similar. Also identical speaker outs, also similar guitar inputs (just two more).

There’s also a BIG FAT choke reminiscent of the ‘old’ Plexi amps.

This amp differs with the Board neatly mounted vertically across the back of the amp (where the controls are at the rear of the amp and shown in green on the image above.


That board has some serious stuff on there as follows:


DSP Chips possibly for Reverb

While this innocuous chip by Texas Instruments does not look as if it does much, here’s a little snippet of what’s in there – don’t worry if its all a little technical – who cares? its just nice to know that Marshall are not using any old rubbish in the build:


TMS320VC5401 Features
Advanced Multibus Architecture With Three Separate 16-Bit Data Memory Buses
and One Program Memory Bus 40-Bit Arithmetic Logic Unit (ALU), Including a 40-Bit Barrel Shifter and Two Independent 40-Bit Accumulators
17- × 17-Bit Parallel Multiplier Coupled to a 40-Bit Dedicated Adder for Non-Pipelined Single-Cycle Multiply/Accumulate (MAC)  Operation. Compare, Select, and Store Unit (CSSU) for the Add/Compare Selection of the Viterbi Operator Exponent Encoder to Compute an Exponent Value of a 40-Bit Accumulator Value in a Single Cycle. Two Address Generators With Eight Auxiliary Registers and Two Auxiliary Register Arithmetic Units (ARAUs). Data Bus With a Bus-Holder Feature.

Extended Addressing Mode for 1M × 16-Bit Maximum Addressable External Program Space
4K x 16-Bit On-Chip ROM
8K x 16-Bit Dual-Access On-Chip RAM
Single-Instruction-Repeat and Block-Repeat Operations for Program Code
Block-Memory-Move Instructions for Efficient Program and Data Management Instructions With a 32-Bit Long Word Operand Instructions With Two- or Three-Operand Reads
Arithmetic Instructions With Parallel Store and Parallel Load , Conditional Store Instructions, Fast Return From Interrupt
On-Chip Peripherals − Software-Programmable Wait-State Generator and Programmable Bank
Switching − On-Chip Phase-Locked Loop (PLL) Clock Generator With Internal Oscillator or External Clock Source − Two Multichannel Buffered Serial Ports (McBSPs) − Enhanced 8-Bit Parallel Host-Port Interface (HPI8) − Two 16-Bit Timers − Six-Channel Direct Memory Access
(DMA) Controller

Power Consumption Control With IDLE1, IDLE2, and IDLE3 Instructions With Power-Down Modes, CLKOUT Off Control to Disable CLKOUT, On-Chip Scan-Based Emulation Logic,
IEEE Std 1149.1† (JTAG) Boundary Scan Logic, 20-ns Single-Cycle Fixed-Point Instruction
Execution Time (50 MIPS) for 3.3-V Power Supply (1.8-V Core), 144-Pin Plastic Low-Profile Quad Flat pack, (LQFP) (PGE Suffix), 144-Ball MicroStar BGA (GGU Suffix)


To most of us, this reads like gibberish, but in fact, this chip has a wealth of features and it’s easy to see why someone would choose this DSP to integrate in to their control, not least the 4k rom and 16k ram. There are other features for timing, and three 16 bit busses for data.

Personally I reckon this is used for far more than you might think – but I guess Marshall will not be telling anytime soon 😉

There looks like some external memory on the back board:


This looks to me like on board memory, maybe static ram.

The above looks like static ram to me – I could be wrong, but manufacturers often use this sort of stuff to store settings that change (rather like bios settings on a PC).



The Atmel ATMEGA8

I use these in the industry I work in and we reprogram these for various tasks as needed. We can reflash these to update the program on there and make the processor do other things. Its a RISC based low power microcontroller.

There really is a whole plethora of digital stuff on that back plane of the YJM100 amp.

But that is to be expected bearing in mind the Noise Gate, the Reverb, the Distortion unit and of course the Power Reduction circuitry. Oh and don’t forget to remember that controller for the floor pedal and the effects loop.

Whether these are all ‘out of the analogue path’ is an interesting question that maybe Santiago Alvarez might answer some time… I’m sure he will!

Santiago Alvarez: The ICs: The TMS320VC5401 + the CS12LV + memory in the socket are used EXCLUSIVELY for the reverb. The Atmel microcontroller takes care of all the switching, the power control and the noise gate. By the way, the noise gate is an evolution from the Kerry King one with mixed analog and digital control. Yngwie’s guitar has extremely low output pickups and the gate control can get a bit tricky.
Tony: So now you know!



Once again I noticed that the control pots on the amp (at the front and the back) are non-standard. I always wonder about these sort of things. Think of it this way, if these were fitted to a real ‘Plexi’ from 1970 and we looked at that amp today, would all those pots be working, no crackles, no pot failures at all, no dead spots? You don’t think so? really?

Maybe they work in a different way on this layout, but I can’t help thinking once again that these long term could be trouble. Marshall say not.


Just so you can see them too – here are the control pots – unfamiliar? right!

I remain to be convinced. Simply because if one of these does fail, you are not getting one soon – especially on Friday night. Compare these with Mesa? Don’t bother – Mesa wins hands down and that is my firm belief about these. Maybe they won’t fail? But….

Santiago Alvarez: Regarding the pots. They are not custom made at all. In fact you can see green ones and blue ones are already from different manufacturers and you can order as per their catalogues. They won’t sell you just 1 or 2 but they are not made as per our requirements either. Don’t also believe that other manufacturers order pots “off the self”. As an example just for a so called “log” pot there are 6 different taper variations. If you then add the mounting type, thread type, shaft type, length,etc, etc. the number of variations start being a considerable number.

Tony: Frankly, I did not quite say what I mean here. What I really was getting across is that these pots appear to be difficult to source easily and are far less common than the regular old style of pot. I’m pretty sure they are not sitting on the shelf of many of the electrical shops you might take your amp for a quick fix (especially on a Friday night, it might just be the TV man). I can’t be exactly sure about those Mesa Pots, but I am sure you could find something to work. In the case of these on the YJM100 even the shape is obscure. I still don’t like them – you might. I like the simple ones…



Some of this has to be the same in this review as the AFD100 – there is common ground between the two builds in many respects although the amps are simply different.

The EL34 tubes mount in sockets directly soldered to the main PCB. I have mentioned this before about heat, but Santiago Alvarez from Marshall did say that the heat transfer is minimal. I’m sure there will be some but am not too concerned about that because of Santiago’s comments.

The preamp tubes are mounted in a similar manner.



Coming presently – watch this space – I only have so many hours in the day!


BACK OUTSIDE THE YJM100 (in case you get bored)


This feature is extremely similar (if not the same) as the AFD100.

Basically, this is a simple way of reducing output power from 100 watts to 0.1 watt which is ridiculously low output. But wait – there’s more!

Because this amp can be switched to 50 watts the figure is divided by two giving something like 0.05 watt out. Can you hear it? you sure can, but it will not wake up the baby.

Power Scaling was an original idea by London Power (not London UK) who came up with a neat idea to reduce the power of the amp in a particular way. I talk more about this in the AFD100 review.

Marshall have their own take on this and I guess the results are similar, although I know that Marshall changed a few things along the way from the London Power method.

One of the main ‘problems’ of the ‘Plexi’ amp was volume. Its a perplexing thing, you either cranked it and got ‘that’ sound, or left it turned down and didn’t! Attenuators had an effect on the tone big time and still do – but not the Power Scaling on the YJM100.

So bearing in mind in Marshalls own words that this YJM100 is basically a ‘Plexi’ design they had to do something to calm down that Lion. Although the roar of the Lion on the Plexi is earth shattering when cranked – so is the tone – and many say that the Marshall stuff today has no ‘soul’ ‘like the old kit’.

Really though, the world is a different place and volume to those old levels would not be tolerated (at least here in the UK it would not) for too long. Firstly you get a visit from the cops… who ask you to play – really they are checking your volume… and then ask you to turn it down… if you don’t? when they return, they take you with them 🙂 Been there – done that 🙂

Santiago Alvarez: The power control works on similar basis as Kevin O’Connor’s “power scaling” implementation does and both are based on previous patents (now expired) like the US4286492 by Claret. Kevin has made it popular and published plenty of literature about it and he definitely deserves his credits. Our circuitry is not his implementation straight away (for example we don’t track the HT) and we also modify some parameters that he keeps fixed and vice versa. This is not done just for deviating from his works but because we considered it works better for what we want to achieve. This isn’t as well any sort of polemics, just clarification, Kevin and I have been in touch with each other on several occasions and I hold him in high esteem.
Tony: These comments in some ways show how innovation takes place. This is not a dissimilar methodology than any other innovation. Lets face it – if you had to reinvent the wheel from scratch? Well I guess that we might be playing through tube amps as big as the room you are in (even bigger than the YJM100) so it’s reasonably easy to see that near enough every manufacturer can ‘evolve’ circuitry based on earlier designs. They get in trouble if there’s a patent infringement, but like Santiago Alvarez said – the patent had lapsed so others can base designs on that original and redesign accordingly.



It’s hard to get away from that AFD100 with some of this, its exactly the same or so near you cannot tell the difference!

And so it is with the auto biasing feature of the YJM100 amp. I’ll repeat what I said in the AFD review…

‘Another neat feature is the ‘auto’ biasing of the power tubes. The AFD100 uses 6550 tubes (the YJM uses EL34 Winged C tubes Russian made) but in fact you can use near enough all octal base tubes with just a few exceptions – so you could use say 2×6550 and 2xEL34 and the amp can basically solve the issue of impossible to bias tubes. Its worth noting though that this feature is NOT completely automatic in its operation. Firstly you have to look at a table in the back of the manual that refers to input power AND bias voltages for different tubes. Then you set a preset on the back of the amp to match the tubes fitted and lastly run through an automated feature where you hold the loop switch on while turning on the amp.’

Santiago Alvarez commented at the time ‘There is a reason for making the feature semi-automatic. We wanted the amp to be as close as possible to one with standard bias so the natural dynamics are preserved. There are some other systems that monitor the current while in use and adjust the bias continuously but that would be different from a classic biasing topology. The fact that you need to start the biasing procedure could be understood like biasing the amp once and then closing the cabinet, having the bias fixed to what ever we wanted.’


The bias feature on the back of the YJM100



Some of what this amp is all about is the noise gate and the overdrive (we’ll call it that) which turns this amp in many ways from any old ‘Plexi’ to a roaring monster.

The noise gate is a clever one (remember those chips) which knows about sustain or instant stops etc. and acts accordingly.

And I can tell you its excellent and works perfectly – one of the best I have used.

Linked with this is Yngwie’s distortion pedal. But on this amp its built right in.

I wonder what DOD said? You see, Yng was known to use a DOD pedal (at least that’s what he said at the time) in front of his amp… well maybe that story I was telling you at the start of this review has changed once again and is now the consistency of myth. Maybe Yng (what a great name) has always used something else and maybe the DOD Yngwie J Malmsteen pedal shown below is myth too? Well no its not a myth, but maybe Yng just wants to forget it?


The YJM308 distortion pedal from DOD

Maybe this pedal is still available – maybe it’s not. But the whole point of raising the issue of this pedal in the review is that it cost me £39.00 to buy. Look at the controls? Look familiar?


Booster on the back of the YJM100 amp

Maybe volume and level are different things. Who knows, but Yngwie used the YJM308 he said? So I guess the ‘booster’ in the YJM100 is similar to the one from DOD – that’s a reasonable statement and conclusion to make. Unless Yngwie wanted a new distortion?

Of course, back in the day of those first albums from Yngwie only he knows exactly what he was using – it certainly was not a DOD YJM308 – I think I am right in saying that they did not exist.

But neither was he using a YJM100.

One way of reckoning on all of this is simple. Buy a Plexi (preferably old or even a reissue), get a YJM308 and a Boss Noise Gate (£50 ish) and the total could be less than £1000 all in.

Or maybe (if you follow the myths and forum boys etc.) get a Marshall 50 watt then you will be cooking on gas!

AND you will be able to pay the gas bill… at least here in the UK you would on the £600 or £700 you would save against the YJM100.

But it’s never that simple – is it?

Stop a moment and think… what about that Power Reduction, and that great Reverb? Hmmm maybe this YJM100 is a little more than the sum of its parts.

And there is more of course….

Santiago Alvarez: The booster… well, without talking about brands and, in a very general manner, any circuit that is not protected under a patent can be used.. You can start counting how many “hundreds?!” of manufacturers copy Marshall circuits. Other issue are the cosmetics, which by the way plenty of manufacturers copy Marshall or Fender and live with it as if nothing could happen. Saying it bluntly as trade dressing, intellectual property and the likes can be very complicated issue, you could copy a Mercedes car making sure none of their patents are included but just make sure that when people see your copy it doesn’t look like a Mercedes.

Tony: Of course, Santiago is correct – if the Marshall amp over the years has not been subject to copying by way of ‘clones’ then nothing has. And with a Brand as renowned as Marshall then that can be a good or bad thing, depending on your point of view. I’m not always convinced that ‘copies’ are best – check out the ‘Chinese’ Ibanez 7VWH shown in a review on this very site – awful. But my opinion on these ‘copy’ products is this: a) if the copy is bad it can have an effect of devaluing the real kit (as in that Chinese Ibanez) and b) that in turn can hurt the innovator, so illegal copies are bad, but enhancements of original designs (the Power Scaling is a good example) can be a way of innovation of products as in the case of the YJM100.



Well you forgot about that? or was it just an oversight?

In either case, the cheap options might not have these two fitted – indeed its likely they will not be there. The effects loop Marshall say is a completely bypassed when not in use thing, and the foot pedal? Awesome control through a simple cable.

I liked the serial effects loop too – parallel loops can drive you dotty. Fortunately this one is the right one in my opinion for this amp.


The foot controller of the YJM100

This is a great foot controller (as all these are on the Marshall amps). Its made of steel and is as solid as you can get. A great addition which you really miss when there is not one on the amp. Ask ANY Plexi user.

These two make a good amp really great. This foot controller is far superior to the AFD100 one in near enough every way. If you hit the boost (turn it on) then the pedal automatically turns on the noise gate too. You can turn on the noise gate by itself as well as turning off the noise gate if the boost is on also. The reverb and the loop are independent of everything else.



Hey, what’s Tony going on about now? This is a Marshall? Right? Quality and Marshall are the same thing?

Well, actually on this occasion they are not – and I really wanted to share with you the things I found on this amp right out of the box – they are a little concerning.

If you look at the large picture of inside the amp which I spent some time on, it all looks great. It is.

But that was after I spent some time realigning the resistors with long legs on. Some were bent well out of shape and believe it or not one was actually touching another resistor on the PCB. Heres a picture before I fixed it:


Hard to see but look close in the middle of the board to the left of the grey cable

Those two resistors are touching each other!

Heres another resistor worse for wear:


Much easier to spot. But the other one above appeared to be dangerous.

Lastly, here’s a shot of the first one after a good talking to:


Here is the fixed resistors from image one above.

Now no one is decrying the overall quality of the product. But frankly, for this sort of money I expect the insides to be as good as the outsides – wouldn’t you?

And secondly, those two resistors touching each other in this way could maybe have caused damage to the amp, me, or indeed you. I admit, I have not analyzed that issue to the n’th degree – but common sense says these should not be touching and shorting something in the circuit out in some way. Lucky I opened it up first.

Santiago Alvarez: The resistors touching. Well, nothing at all, those pins are connected internally already. If we had wanted something not potentially touching we wouldn’t have implemented them that way on the pub. Please see the attachment. In any case, if any two were touching and causing a short (for example a solder bridge after wave soldering) the amp would have failed straight away the pcb tests even before being assembled into the chassis.


Tony: Its fair to say that I did not check the board circuitry down to track level. And Marshalls image shown here does indeed confirm that the two pins of these components were linked anyway. But that might not have been the case – and it was a little shocking (no pun intended) to see those items on this amp looking like they had just been thrown in there. Surely its no big deal to look at the overall condition of the components and ‘tidy’ them up a little – if only for aesthetics. Nevertheless it is a mass produced product. One thing is for sure, this amp was not exactly what I would have liked to see inside – especially at list price where the dealers discount nothing (seems to be a trend). FYI this amp was changed for a ‘sealed’ boxed unit from the dealer and that amp build was decidedly far more tidier inside thankfully, and without free scratches from the dealer. A sealed amp from Marshall is what you should buy – check it out at the end of this review.

But that’s not all.

Heres a shot of the amp underneath (remember right out of the box from the factory! (but was it? read more below) :


Clear scratches (some reasonably deep right out of the box).

Now I could blame the dealer. I could blame Marshall.

But these scratches were there right out of the box on a brand new amp. I am going to complain to the dealer anyway. Either he sold me a ‘used’ amp or its from Marshall. Simple either way.

Update (yes already): The dealer said that he ‘just plugged the amp in’ to make sure it was ‘OK’ in his words. I have sent him images and a nice email – I’m like that. The dealer has offered to change the amp for a FACTORY sealed amp. I have taken them up on that offer and there is no doubt that I will update this review at the end regarding exactly what I find on the second amp – now THAT should be really interesting. Maybe this amp under review was hopefully a ‘one off’ or a ‘Friday afternoon’ amp, who knows? All will be revealed on the replacement and my findings about that amp and the comparisons of the two at the end of the review in due course.

But no matter what – that resistor stuff is factory there is little doubt.

These things do happen, but that’s why quality control is there – and the documents are all signed confirming the QA on this amp was perfect.

Conclusions on the QA? Needs work – in progress – for both the dealer and Marshall on this amp. Like I said, tell it the way it really is!

There were no issues like this on the AFD100 – and that was a cheaper amp.



I used the 1960B cab from Marshall for this amp as it was the cab that Marshall recommended its customers to use.

Its a big cab really, being the bottom one in a Marshall stack. As you saw earlier, the amp takes up real estate space (maybe one of the reasons why Marshall said to use this cab) and maybe the 1960A cab would not have been wide enough to take that extra girth of the Marshall Major amp cabinet – I did not check that. The amp IS big! Remember I said it – I highlight nothing that does not matter.

I used the right one and set everything to 16 ohms as I always do.

I also used a Monster cable for the cab to amp and discarded the one from Marshall. There’s nothing wrong with the Marshall cable, but I had the Monster one so used that. Now I don’t condone cables – I certainly don’t believe for one minute that you can ‘hear’ the difference on a speaker cable – I don’t have a lot of time for ‘experts’ who can either. And the costs are extortion. I used it simply because its made a bit better and that’s it! So don’t waste your money – you need it all to buy this amp.

I set most things in a reasonable manner at first with all those bells and whistles turned off in the 100 watt mode. Yes – its a ‘Plexi’ sound alright and if you have heard one (you will have) or rather played through one you know it immediately.

The ‘Plexi’ thing for me was always an issue back in the day because there was inadequate gain for the way I play guitar. I like really great crunch and great singing leads to work with.

So firstly, I turned the Power Scaling up (about half way) and cranked the amp.

In fact I had joined the two channels (as I used to do on an original Plexi) and cranked it all up.

With the power scaling in, it was a Plexi but not as we know it. There it was, that great sound (the one that Marshall originally came up with all those years ago) and at levels that were shall we say, kind to the ears.

Here were my FIRST settings:


Maybe you can make them out…

The two channel knobs were nearly full on, with the left on backed off a little as you might be able to see from the picture above.

Later, I dropped the output to 50 watts and that was awesome too. One thing I did notice was that if you set the amp for 50 watts, then turn the amp off, when you turn it back on it was defaulted back to 100 watts output. Strange, bearing in mind how much is actually in this amp by way of digital control.

When I dropped in the noise gate and the drive this amp took on another level of sound – and another meaning in life. No more was this amp a pussy footed Plexi – it had turned in to that sound you have heard thousands of times. I introduced some reverb and played this amp for about an hour. Players heaven.

I achieved so many sounds it was actually hard to believe that this amp could do so many, but in my opinion what it excelled at were sounds like on Black Sabbaths ‘Die Young’ or ‘Lonely is the Word’ and other tracks like Robin Trowers ‘Day of the Eagle’. I could hear Free, Hendrix, Led Zeppelin, the list goes on and on – they were all there – and yes there was that Yngwie tone – superb, but I could not emulate Yng if I wanted too – neither can my bank account. Its a shame I know, but some things are not meant to be and me playing Yngwie J Malmsteen or having his bank account is not likely to be any time soon.

The funny thing is, for me, although I can get those Yngwie tones, I can never replicate his playing. But that’s what I said from the start.

By the time I completed the video review of the sounds of this amp, of course I knew a lot more about how to drive it, what it likes and what it does not like.

It REALLY likes a cry baby pedal. And so do I so that was used with superb results in my opinion.

In fact all I needed was this amp and cab, the cry baby, a decent guitar and that was it.

This amp also likes some volume no matter what you do about the Power Scaling – I found that at about at least 12:00 on the power scaling, 3:00 on the drive and both knobs on the front – the left one at 4:00 and flat out on the right one the sounds were really awe inspiring.

If you check out the video with the playing on you will get a good view of the overall sounds for non Yngwie players from this amp. Its a really great all round (not really a modern detuned stuff amp so don’t buy it for that) classic and sometimes not so classic rock amp.

I am really surprised there are only 1500 going to be made.

The AFD100 had top end that could cut a tree down, but the YJM100 had some of that if you wanted it – but if you didn’t want all or any of that then the amp was much more controllable very nicely, especially with the amp patching in the front input sockets as described in the manual.

I did watch some pro’s demo this amp flat out. You might well have seen them (Hi Rob). There is little point in doing that unless you have never used a Plexi on a stack cranked before (I suspect at least one of them has) – I have also, when the real ones were around the first time and it is an awesome feeling… not the sound, but the sound waves literally hitting the back of your neck. To be honest, when those old ones were flat out on two 4×12 that sound in my opinion was not that great in real life. But there is no reason for that level of volume anymore. I think they lost sight of the Power Scaling aspect of the YJM100 maybe and why its there. Sure its a blast doing all that, but really, it does not prove a bean – except to have loads of guys on forums hiding behind funny names saying how great it all is. But maybe that’s what that dealer wanted – after all, he is not a video maker just to look good… he doesn’t 🙂 – but I agree it was probably fun.

That Power Scaling is there because the majority of guys will NEVER play as loud as those pro’s were testing, negating the option to bother in the first place.

On the other hand, I’m sure that many guys will get along with any Marshall amp that does not dictate to them how loud they have to play for ‘that’ sound.

I know I liked this amp within five minutes of turning it on. And I did not have to go above 1/2 output (at least on the Power Scaling control).


This has been a really long review (and its not over yet by a very long way), but I wanted to try and instill most of the feel and findings of buying a ‘brand new amp’ that most guys don’t do very often. And if you’re a younger guy then that £1515.00 is probably savings from a very long time.

And that’s easy for the ‘fast buck’ dealers to forget – lord knows there are enough of them around.

Recapping on the sound of the YJM100 – whether you play at 50 or 100 watts the amp sounds glorious. I have many amps to compare this YJM with and you know what? This is right up there at the top regarding the sounds coming out of that 4×12 1960B cab – and yes, its likely that the 1960B does instill a particular emphasis on this sound – but it really is for the good.

I said actually on the inside video that I was shaking after first playing this amp and trust me I was – its hard to describe what a really good sound from a Marshall amp can do to you. You know – it was not the volume – and there are not many other things that can do that to me. But ‘that’ sound – the one you have wanted for some time (no not you detuned guys) is absolutely in there – I found the reverb was awesome too along with the noise gate it all worked wonderfully.

So going back to my comments earlier in this review about buying a ‘Plexi’ reissue, a DOD YJM308 and a noise gate? Was I correct? is it worth saving some money? Surely?

Absolutely not!

Remember that this amp has less availability than the AFD100 (which was 2300 worldwide) and this YJM100 only 1500. It always sounds a lot, but in real terms its a few hundred for each country (if that) so these amps are going to be short supply no matter what. And I reckon these will increase in value over time if Marshall don’t issue more.


One thing, I always sell equipment after reviewing it in a fair and reasonable manner and rarely hang on to it longer – firstly because of the ongoing costs (I finance it all myself), and so I can use the money to buy replacement gear to review.

Once the ‘enthusiasm’ wanes and I’ve had the item a while, then I sell. The AFD lasted about 6 to 8 weeks – and the ultimate reason looking back was that the ‘treble’ in the amp was hard to get right. What I mean is that when one ‘channel’ was right then the other was not. That was a little limiting – and the AFD was not a ‘cheap’ amp. I gave it a 10 out of 10 because it really did feel right in the review, but maybe I should have backed that score off to 8 out of 10 and in retrospect – I have updated the score for the AFD100 in its review – downwards.

But this is NOT the AFD review!

This is the review of the YJM100 – the Yngwie J Malmsteen amplifier from Marshall Amplification PLC in Milton Keynes UK.

I hate to say this – but I’m keeping this amp (figuratively speaking – this exact one is being changed for a ‘new’ one).

No its not a quick euphoria since getting the YJM100 out of the box, and there’s the Axe-FX II I have to buy and review soon assuming they can actually ship them some day (vaporware is always like that) and lots of other things I have to do with my life and money, like buying some Budweiser and loose women. If my wife ever reads this of course I’m only joking… or am I?


Then I have no reservation in classing this YJM100 as a supreme and awesome guitar amplifier that effectively puts Marshall back at the top (or near to the top) of the pile in my opinion.

An amp fit for that frankly ridiculously high cost that will stop all the younger guys getting one while they are available for sale. And of course it will stop them later when the price hikes because of production cessation and that’s a REAL shame.

I suppose the UK government at a 20% cut of the price contributes too in their own ‘south of Watford’ way (that’s a bit like being called a ‘southerner’ in the USA). PS: I like all the yanks 😉

And NEVER ever forget that aspect of the size and weight of this amp at 24 Kg (around 50 Lbs.). Think of the guy who wants two… they have to be kidding? right?


Now to the final score:

If this amp had reached me as it should have, then it would have achieved an unequivocal 10 out of 10.

But it did not.

So I’m afraid, that this particular amp (Serial No: shall remain nameless) because of the issues I found surrounding QA is relegated to a 9 out of 10. A pity really because its as near perfect once everything was (or is being) resolved by Marshall / Dealer. Update is that the Dealer is changing this amp out. And so he should for £1515.00.

Suffice to say I never had these sort of issues with Marshall kit before, but then again I have not with Engl, Mesa Boogie, Egnater, Splawn, Ceriatone, or many others.

Lastly, I’ll update this review from here on down the page later when I receive that ‘replacement’ factory sealed amp and do a quick ‘comparison’ between the build of the two. Now that is something to look forward to.

I truly hope that this no bulls*it review helps people to make up their own mind about the YJM100 – and don’t forget to watch both videos – my playing will never be like Yngwie, but in some ways that’s a really good thing – because this amp will be pushed forever to the Yng way of styles by others – there are not many guys that actually take an artist amp and demo it in other ways. But that’s all part of the fun.


After going back to the dealer and pointing out the scratches under the amp, they admitted to having done that damage at the dealership. As you might expect – I was not a ‘happy chappie’ as they say.

However, they did see the error of their ways and I’m pleased to say that they changed out the review amp for a FACTORY SEALED unit. So they DID do the right thing.

Check out the ‘mini’ review below to see if there was any improvement inside and out! and look for the rating of that amp. See what I say about the sound comparison between the two.


Finally – MY YJM100 Amplifier!

Yes I was dragged down the road a little on this one. As it turned out ultimately, like I said the review amp went back and I got the replacement which is really the amp I should have got from the dealer for my LIST PRICE amplifier in the first place. To be fair (really?) to the dealer he did see the error of his ways and changed out the amp at his expense (and so he should) so he did correct the problem and I am grateful (?) for that. The dealer was Guitar Guitar in Scotland. See I DID tell you it was for a review! Now you will be (in)famous forever. But actually he did what was right – so he supports his customers which is more than some might have done.

I have a local dealer (discussed in the first part of this review). I would have preferred to give my business to a dealer I TRUST & KNOW and not one who I have never really bought from before. My regular dealer in the UK is Academy of Sound and they tried hard to get me the amp for review as soon as others had them… but alas, on this occasion they were given promises by the rep over and over again about delivery, but nothing firm – hence I had to look around. A review 6 months after the kit arrives is basically useless.

Advice – stick with the dealers you know and trust.

In any case the replacement amp serial is M-2011-27-495-1 which makes this amp just a few amplifiers away from the one on review above.

But there is a difference in the build quality.

I have made a quick video of the insides and outsides of that amp:

Video of 495 here – presently

As you can see in the video this box was completely sealed as it arrived. Look for that on your purchase too. If your box comes resealed you really need to ask yourself why. Maybe your amp will not be as ‘new’ as you would like it. Maybe it will even be the one from review who knows!

Notice that the case on this amp has no scratches, blemishes, rips, tears, scuffs or anything else wrong with it – and that’s how it should be.

And inside? I found one resistor that was ‘squashed’ a bit, but nothing like on the previous amp. In fact I still did align a couple, but it would have made no difference to the operation of the new amp – it just looks better – and for my £1515.00 I like it that way.

You would too – right?

Strangely enough, those same four people who were responsible for the build of the original amp are listed on the original build sheet of the replacement 495 amp, namely:

1. Tony Weir – 16/06/2011 – Production Line Assembly

2. Betty Wilson – 16/06/2011 – Testing

3. Martin Patton – 19/07/2011 – Finishing

4. Mark Reeve – 19/07/2011 – Final Test and Inspection

Santiago Alvarez did say that if the bending of the components was dangerous then the amp would have failed at test. He’s probably right. I’m glad he is!

But I know of no other reviewer anywhere in the world that has gone to the lengths that I have in this review. And it’s just good to know that while there might be the odd silly thing here and there which are generally easily fixable, that there are variables in each and every amplifier – and those can be added too by the dealer! But of course – you will know a little more after having read this review. How many other reviews EVER give you this level of detail? I suspect none…


But for one last time I’ll confirm that this amp really is a keeper. I sold the AFD100 because of that all encompassing treble (read above) which was not controllable easily and it always affected the other ‘channel’ or sound.

The YJM100 on the other hand? There is treble in there (just like the Plexi and even the JTM45 – indeed very similar) but like those original amps, the YJM100 is easily controlled. The reverb is very good and you can think of this amp as a two channel amp (even though its not) thanks to those other additions. The power reduction is welcome too. The 50w seems to hang on to notes a little longer.

Rating for the replacement factory sealed new amp?

I thought you would never ask!

If the amp had arrived in the condition inside and out of 495 (the replacement) then the original score might have been higher.

But this 495 amp was just about perfect so the final review for amp 495 gives this YJM100 amplifier from Marshall Amplification PLC a 10 out of 10 – even with those tone pots fitted.

One thing to be aware of was this. My use of either amp yielded EXACTLY the same sound from them both. So even bearing in mind the original units build (but after the components were placed as they should have been) both amps sounded the same – awesome.

My first video of the sound really has not particularly done this amp justice (video compression and eq) so I’m currently working on a pro recording so you can get the real tone in your head. But remember – my tone might not be yours… its all a little subjective. One thing is for sure though these YJM100’s really are awesome sounding amps.

Maybe it might have gone to 11 if they had put those other tone pots in there.. like on that other famous Marshall amp that also used to go to 11 😉 someone should tell them 🙂

Things I liked about the 495 amp:

  • Sounds
  • High quality power tubes (Winged ‘C’) EL34
  • Power scaling feature
  • Reverb – digital but sounds great
  • Drive circuit and the noise gate – work perfectly
  • Effects loop
  • Auto biasing of the power tubes
  • Floor pedal – and the thing about how the noise gate turns on when you hit that drive
  • Red Ferrari cover 🙂 I just need the car now.
  • Little red link cable included

And some things I really could do without:

  • Price – £1515.00 is just a little high for the UK in recession
  • Bent components on the PCB – check yours (MUST be unplugged from the mains)
  • Knobs round the back – hard to set when the amp is on a 4×12
  • Ridiculous ‘certificate’ that is a print with no real reference to the amp you buy.
  • Weight is 24Kg
  • Its big
  • Long wait for product and very limited availability
  • No ‘exact’ Yngwie settings included for the Yng fans
  • Meddling dealers – guys – leave them in the boxes! meaning well does not always do what you intended

I guess that sums up the YJM100 Marshall amp in a way that no other reviewer ever has!

I would like to thank you all for reading this far  – and not if you never made it to the end of this awesomely long review. And of course for visiting my website – its been here forever… like me.

Now get out there and buy one! Tell em Tony sent Ya…


This review and all content ©&® A B Mckenzie 2011 –

Please do feel free to link to this review but do not steal the images or text without my written approval.