I made a video recently detailing the facts about the Boss MG-80 guitar amplifier.

So far my videos on Jimbo Guitar have concentrated on the Boss MG10, a 10W guitar amplifier from the late 1980s.

But I’ve got its big brother, the MG80, and I thought I would do a facts video to complement the facts video about the MG10 before I get into any kind of demonstration of me playing guitar through this amplifier.

So if you’re looking for more information about the Boss MG80 guitar amplifier well hopefully this can help you.

I bought this one second hand in 2019 but I think they were released sometime around the early 1990s. My guess is that BOSS saw that the MG10 was quite popular but was very very small, and somebody decided to make a bigger and louder version.

So what I’m going to tell you is what I know about the amplifier from owning one, starting with some basic facts.

Basic facts

The Boss MG80 is a small solid state combo guitar amplifier, meaning it has the speakers and the amplifier in the same cabinet. Although it is bigger than the MG10, I think it’s small in comparison to the 75 watt Marshall 5275 combo amplifier for example.

As the name implies it’s an 80 watt combo amplifier, meaning it can output up to 80 W into its two built-in 6.5″ speakers. As with the MG10 although it has two speakers and it looks a bit like the stereo Roland JC amplifiers, it is mono. The two speakers are wired together in series to create a mono output, but we’ll be looking round the back at those later on.

The physical facts of the MG80 guitar amplifier are that it weighs 13 kg or around 28 lb. That is quite a big difference between the Boss MG10 which weighs 4.9 kg or 10 lb, so nearly three times as heavy, and almost certainly that is the transformer and possibly the speakers contributing to how much it weighs, along with, in part, the bigger case.

Regarding dimensions the MG80 is 38 cm or 15 inches wide, 24 cm or 9.5 inches deep and 30 cm or 12 in high.

I measured the speakers at 5.5 inches on the front, but they’re technically 6.5 inch speakers.

Controls

So, looking at the front you can see that it has the same controls as the MG10 although there is a slight difference.

You may spot that there is a second input, one marked high and one marked low. The high input is the same as on the MG10, and the low input has some kind of attenuation behind it. My experience of playing through the amplifier is if you’ve got very loud or powerful pickups in your guitar then having this attenuation or load reduces the input going into the amplifier and this allows you to get a clean tone more easily. It’s really no different to turning the volume down on your guitar except that there doesn’t appear to be any change in tone, and it is a common feature on lots of amplifiers. If you’ve seen any of my sound demonstrations of the MG10 you’ll know that it distorts very easily so this is quite a good feature.

The other notable difference is that the power switch is a push on push off switch unlike the rocker switch on the MG10. Cosmetically the amplifiers look very similar although i personally feel the logo of the MG80 is slightly different typographically to the MG10 – you might be able to spot the difference in the way the words look for example.

Don’t be confused by the green color of the control knobs; I believe when the amplifiers were made the control knobs were the same identical light blue on both models and were the same part. I think that the version that I have here has been in the house of a smoker and the controls look slightly green because they’re stained with nicotine.

You can also spot on this amplifier that the both the inputs and the phones jack have lost their retaining nuts. Iit’s not altogether clear in the picture but the only one remaining is the low input and that is cracked so clearly being made of plastic there’s some kind of lifespan to these pieces of hardware and they eventually split and I guess they break altogether or fall off.

It would be good to replace these at some point – the whole of the control panel is held to the chassis through hexagon nuts behind the control knobs but all the same you don’t want any undue strain from constantly plugging things in and out causing the circuit board to crack.

Somebody has attempted to replace the nut on the high input with a metal one cosmetically it’s not so great but certainly structurally it’s better and it won’t be difficult to find replacements online to replace them I’m sure and that’s something I’ll do one day.

You can see it has the same plastic nylon type mesh over the speakers, it has the same type of vinyl covering the cabinet and the same plastic corners as the MG10 so it really is fundamentally a scaled up version of the original MG10 amplifier.

Cabinet construction

If we go round to the back and we just how scaled up it is in terms of the electronics

Apart from its ability to be louder one of the big differences between the MG80 and the MG10 is it is not a closed back cabinet. If you’ve seen the MG10 video you’ll see that it has a closed, sealed back and it has a port on the front to let the air from the back of the speakers out through the front. Although there are panels on the back the MG80 cabinet is not sealed and you can see there is a rear panel with a kind of oblong in it. This means that air from the speakers going backwards and forwards at the front (and therefore sound) will come out of the back of the amplifier as well.

You can also see that the metal chassis of the amplifier is visible at the top and if we take a closer look you can see one of the differences from the MG10 is that from the factory there is an external speaker socket.

This allows you to plug your Boss MG80 into other guitar cabinets; 12-in speakers, 4x12s anything you want as long as the minimum resistance of the speaker is 8 ohms. Again the retaining nut is showing plastic fatigue with a split in it. There’s also a serial number panel telling you that it’s 240 volts, the power consumption and there’s a serial number on there and also that it’s made in Taiwan. There is also the usual important safety information on there in English and French.

If we take off the first back panel we’re presented with another panel but you can now see on the top left the transformer and on the top right the heat sink.

That transformer is very big and very heavy but that’s because the amplifier is going to be giving out 80 Watts. I don’t fully understand how transformers work but my rough understanding is if you want a lot of power you need a big transformer to efficiently turn the 240 volt mains that we have in the UK into a power supply that can keep the output stage of the amplifier happy. As far as I know it’s always better to over-engineer these things so you’ve got a nice big fat transformer, but transformers are made of layers of steel plates so there’s no getting away from the fact that they are heavy.

The comb shaped thing that you can see to the right of the transformer is the heat sink, although solid state amplifiers don’t get as hot as valve amplifiers do where you could seriously burn your skin if you were to touch parts of a valve amplifier going at full chat they do nevertheless create a lot of heat and the heat needs to be dissipated or let back into the atmosphere away from the output transistors. So this is just like in a car that has a radiator – you can consider the heat sink to be a radiator radiating the excess heat generated by the power it’s producing and being turned into warm air that drifts away through convection away from the amplifier and keeping it running happily and not overheating and bursting into flames.

Speakers

You can also spot the two speakers in the previous image, so let’s take away that second panel to reveal them.

The speakers are marked PEITONE and they are 4 ohm speakers capable of 50 W each. The internet doesn’t have a great deal of information about PEITONE speakers – it merely says that they come from Taiwan so I expect they were a reliable local supplier for Boss and Roland for their Taiwan manufacturing base. They are wired in series, meaning the two 4 ohm loads at 50 watts become a single 8 ohm load capable of taking 100 watts – again, over-engineering is probably a good thing. There is a lot to be said about loads and impedance and speakers and output and I’m not expert in this regard, so i’ll leave it at that for the time being, but I hope that demonstrates how to make a bigger combo you need a bigger box and more power.

I suspect like the MG10 the cabinet is made of particle board, though the inside is black unlike the unfinished particleboard inside the MG10.

Certainly the two panels on the back are particle board but I noticed that the pieces of wood in which the panels are screwed are real wood because I suspect that’s got a better structural strength than the particle board.

I thought a lot about the construction of the back of the cabinet and whether the two panels were meant to do some kind of folding of the sound like a horn type speaker, but on reflection that would require the rest of the cabinet to be sealed and with all of the air that will be lost through the chassis of the amplifier and elsewhere what I actually think is that the back of the amplifier is designed to be able to stow the mains cable safely without it damaging the speakers. That was a bug bear of mine about the MG10 that you can’t put the cable away anywhere – it seems to work quite well on the MG80.

Of course stating the obvious it is a mains powered amp and the amp is hardwired – there’s no way to unplug the cable and it comes in my case with a molded 3 pin UK plug for our 240 volts power.

In summary

I can tell you without playing it in front of you that this is a much much louder amplifier than the MG10, but its size still means that it would struggle with a real life drummer and it would struggle to be heard over a band. That said it’s a very shrill sounding amplifier and shrill sounds travel much
faster than heavy sounds.

There’s a whole lot of science about perception of sound and so on and so forth that I’m not going to get into here, but like I say this is very very loud, but by sheer design it is a bit of an oddball compared to the type of amplifiers you can buy today.

It is louder than the MG10…but compared to the Marshall 5275 it’s not as loud. The Marshall is a 75 watt amplifier, though you should know by now that watts are a unit of power and don’t equal decibels.

There are all sorts of things that go into why an amplifier is loud or not. There is certainly no difference between “valve watts” and “transistor watts” incidentally, but there are very very different definite differences between the components that make up a combo amplifier, including the speaker and the transformers and the output stage and it’s how those are balanced and put together and the recipe that the manufacturer used that gives a combo its volume, overall sound and character.

You don’t always want deafening loud volume, and there are various reasons why you might want this amplifier – certainly if you find one for a reasonable price you should get it as it won’t take up much space…but it is heavy.