Some Boss MG-10 facts

From what I can tell, I get a fair few hits on this site from people wanting to know more about the Boss MG-10 amplifier, and since I have had one since they came out in 1989 (and now have three) I thought I’d post about what I know about the amp, starting with some basic facts.

If you didn’t already know, the Boss MG-10 is a small solid state guitar amplifier. Solid state means it doesn’t use valves (or vacuum tubes) and that fact alone will alienate a whole bunch of guitar players, but…whatever.

As the name implies, it’s a 10 watt combo amplifier, meaning it can output up to 10 watts into its two five inch speakers. Although it has two speakers and looks a bit like the stereo Roland JC amps, it is not stereo – the two speakers are wired together in parallel to make a 4 ohm load.

Boss MG-10 amplifiers

The cabinet is closed-back, and the front baffle has a cutout between the two speakers which stops the whole enclosure from being “sealed” without being “ported”. If you don’t know what I’m talking about, honestly, don’t worry. You can just see the cutout in the photo below, a circle between the two speakers at the bottom of the baffle.

Being a closed-back cabinet there is nowhere to stash the hard-wired mains power lead, which is one of the most annoying things about it, given that it’s a small amp and therefore portable. Mine came with a plastic strip on the cable for wrapping the cable up, and it worked for years before falling off. Mine also came with a moulded UK 3-pin plug. You can wrap the cable up and stuff it into the carrying handle, but then you can’t use the carrying handle…

If you look at the photo above you can see my original amp on the right. I moved the carrying handle from the top of the amp to the side so that I could stand my Yamaha REX-50 effects unit on the top. The amp on the left was a later acquisition and has the handle on the top where it was intended to be.

As is standard for lots of small combo amps the carrying handle is actually what holds the amplifier chassis inside the cabinet. Over time the black steel parts of the carrying handle rust, so if you see an amp like this second hand and those parts are rusty, don’t let that put you off.

The cabinets are made of particle board and are fairly sturdy, but not indestructible. One of mine has been damaged in the past, but more of that in a different, forthcoming article. The cabinets are covered in black textured vinyl with black plastic corner protectors. The speakers are covered with black nylon mesh which has proved very sturdy on mine over the last 30 years.

Boss MG-10 solid state amplifier

According to the manual the amplifier measures 32 x 24 x 17 cm (about 12.5 x 9.5 x 6.5 inches) and weighs 4.9 kg (10lbs). The amp itself is quite balanced (big amps tend to be heavier wherever the transformer and speaker magnets are) and is a really cool size.

It has seven controls on the front for shaping the sound – gain, volume and master volume controls and bass, middle and treble and presence EQ controls. If you are familiar with guitar amplifiers you will know that more gain and volume = more overdrive/distortion/fuzz (like a punky, heavy-metal sound). Master volume controls the overall volume. With all the EQ on zero there is no sound at all. You can “pull” the master volume control to engage the “warp” function which kicks in a different type of distortion, and removes the bass, middle and treble controls leaving just the presence doing anything. Presence is like super-duper treble.

There’s one input, a headphone jack (which I’ve never used) and a power switch. Being solid state it comes to life immediately after you switch it on. The seven controls have blue-topped control knobs. All of mine on my original amp survived, but the two I subsequently bought have both lost at least one knob (see the presence knob below), and just about every one I’ve seen on eBay has been missing one or more knobs. This may have something to do with the “warp” control being on a pull-control and eventually being pulled right off forever. Sometimes too the knob remains but the blue top goes missing. Boss/Roland do not make replacements.

Boss MG-10 amplifier

I’ll make a video one day about the sounds as it’s just easier to play them rather than describe them, but suffice to say this amp, with its 10 watts of solid state power and two five inch speakers is NOT a heavy sounding amp in the same way that a 12 inch speaker can be – those two five inch speakers just don’t deliver a lot of bass. But you can get a huge variety of sounds out of the amp, from clean to exactly what you can imagine warped distortion sounds like. It’s also really, really loud for a little 10 watt amp.

But it won’t sound be loud enough to compete with a live drummer, and it won’t sound like a plexi, or an AC-30, or a twin reverb. It sounds, instead, like itself. If you have bought one and are wondering whether it’s any good or not, it’s a great amp, trust me. But just remember that it’s a 10 watt practice amp, not a classic tube stack or anything else. Let it do its own thing!

As I said I’ll make a video about the sounds one day. In the meantime check out some of my existing videos of the amplifier.

Boss never made any variants of the MG-10, for example a head-only version. So if you see one of those, someone got out the hacksaw. They did make the MG-80 a few years later, which is an 80 watt version with two 6.5 inch speakers. I have one of those two and they are bigger and heavier amps. I’ll make a video of that too one day.

Watch this space for an article about the limited information I have about the circuit.

10 thoughts on “Some Boss MG-10 facts

  • Hey I picked one of these up recently and it’s a really interesting wee amp! Could you tell me any more about this amp like is there a schematic available for it?

  • Hi John, glad you’ve got yourself an MG-10 and find it interesting. Not seen a schematic for one yet – alas I don’t understand electronics very well so whilst I am planning a video about the circuit, I don’t have any expert knowledge of how it works and will only be talking through the bits I can identify. Do let me know if you find one however!

  • Thanks for the run-through, Jim. These practice amps get a bit neglected, but I think that’s what we end up using the most (speaking for myself as a bedroom would-be musician). What are your thoughts on the MG80? I know it also has two small(ish) speakers, so I would imagine you also get more focus on mids and highs, only louder. There’s always a couple of them around down here in Brazil (Roland had a local factory here in the 80’s called Oliver), but I never had the chance of playing them.

  • Hey Dave, thanks for stopping by. The MG-80 is a strange one. It is loud, but I can never be certain it could be as efficient with those two small speakers. I am not sure it could compete with a drummer for example! But a 50 watt amp with a 4×12 would probably be fine.

    Interestingly it has a speaker output and I have tried it through a 2×12 cabinet. The one thing that stood out was how limited the bass was – there was no way you could “djent” with this amp. I am not sure if that is a problem 😀 but it is noticeable.

    So in some ways, although it is probably best as a strange small but powerful combo, it is certainly nice to have a bigger louder MG-10, and I would like to check out the circuit to see if the pre-amp is the same as the MG-10 (with my limited electronics knowledge).

    If you can find one at a reasonable price, why not try it and buy it? I had to wait for a long time for mine as they are not easy to find in the UK. The idea of a Brazilian Roland is very exciting to me – I would love to visit Brazil and check out the music scene there!

  • This was my very first amplifier in 1989. I got my first “good” electric guitar, and this amplifier to go with it. I still have it and use it as a travel amp, or hotel room amplifier. It really does have some interesting sounds and really, is not a bad sounding amp. I run pedals on it from time to time, and it takes them well.
    I recently did a search to find a owners manual or any other information, and found this blog.
    As I do not see many of these around. It is nice to see someone else enjoying them.
    Thanks for the blog!

  • Hey Mike, thanks for your comment and observations. Nice to know you dig these amps too. I’ve never really tried pedals with this amp which is a bit crazy as I have LOADS, but good to know it can take them – with all that gain control I am not surprised really 🙂 Keep rocking!

  • Hi everyone. I too now have one of these amps as part of a recent acquisition. So, the first thing I noticed is the thing buzzes a lot, especially when I pull Bass/Warp knob. I opened up the back and it’s a simple circuit board but, Im not really versed with the electronics end of it. I can however, pull one of the speaker connectors to only allow one speaker to go on and sure enough, it sounds better with only one speaker. I see that Ebay is selling 15 watt 8 ohm 5″ speakers that will fit for under 25.00 with postage so I might just take a chance and try some new cones in their just for the heck of it. Note: I unplugged it every time I reached back there as to avoid any electric shock. Also, sometimes the capacitors store voltage in them so its best to let the amp be unplugged for a while if you’re going to be playing through it for a while. My process of elimination took about 7 minutes tops. Im 99% sure it’s the speakers but Im a little concerned about the warp circuit as well. Since the speakers are returnable, I’ll probably just do it. If I come across a schematic, I’ll be sure to download it as well. Cheers everyone!!! Victor in California

  • there are several heads on net that are identical with chassi above the controls..they are in the 2012 way to add a pic here

  • Victor! I have no idea why I did not reply earlier, other than you-know-what (the story of 2020!). Thanks for sharing your experiences with the MG-10 mate. Did you get any further with your speaker experiments?

  • Bill, thanks for your comment! What catalogue are you referring to? I can’t see anything in the Boss 2012 catalogue?

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