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Technical & Product Guides




 Why do your amps have such high power ratings when I only need x amount of watts?

It may seem like a lot at first glance but there is a reason for this. All solid state amps are usually rated at their optimal impedance. Usually 4 ohms for most amps.

So the figure on our amps is that rating when the amp is receiving it's optimal input signal and the volumes are on full. Now when a solid state amps encounters a higher impedance the amp has to work harder. The amp delivers less power because of this. Usually around half the power before. So if at 4 ohms the amp can give out 400w, at 8 ohms it can only deliver 200-250w. At 16 ohms the amps power drops even further to around 100-120w.

This wattage when the amp is working hardest is the important figure to us as guitarists as this is the power rating that most guitarists would consider as matching that of a tube amp head. So we wanted to make sure our amps had enough power at 16 ohms to compete with a loud tube amp and have enough headroom and volume to run even on a big stage.

Solid state watts aren't as loud as tube watts so there is no way your amps can be as loud can they?

This is a misconception.

A watt is a watt whatever the source.

The confusion comes from how tube amps are measured for their power. They are only measured to the point of distortion. Also from how solid state guitar amps were often misleadingly specified in their power rating.

Now we know that tube amps don't take much to get to that "distortion" stage (and when they do they distort in a very pleasing manner) so in effect when a tube amp says 30w, it's more than that. Some 30w tube combos can easily be used on stage, as can a 50w tube head. This is because they are putting out a lot more than their "rated" power. Stage volumes tend to be around 60-100w depending on the style of music and band playing which then explains why those "low power" tube amps can do that as they are actually putting out more watts than they say they can. So what does that mean in the tube vs solid state battle? Well for one you are not comparing 30 tube watts, it's more like 60 or 80 and that real world level versus any other 60 or 80w should be the same (using same sensitivity speakers, input signal etc). That is one of the reasons our amps have so much power so that when they get to 16 ohms they have enough to still compete with a tube amp in on-stage conditions.

Also remember above when we mentioned that solid state amps work harder and lose power at higher impedances? Well standard practice is to label the power section at the rating for 4 ohms. So although that solid state combo may say 100w as that is what the amp is rated at for at the lowest impedance. In actual fact, using a higher impedance 8 ohm speaker has already dropped the power. That 100w combo is now probably 50 or 60w, less if the speaker is a 16 ohm one. So people see a 100w combo and think, oh 100 solid state watts is nowhere near 100 tube watts when the fact is, it isn't even 100w. You can see how a combination of both of the above can lead to the misconception. Bad design or bad marketing or both?

So if your amps are so powerful will I blow my speaker?

Great question and any amp (especially a tube amp which delivers way more power than it's rating) has the capacity to do just that if pushed too far.

There is one great thing that stops that and that is yours and your bandmates ears.

Too loud and you know that in rehearsal or on stage everything else gets lost. Too loud and your singer or bassist will start throwing things at you!

Too loud and you damage your hearing or it starts being painful.

That level isn't a huge one, as mentioned above, around 60-100w. Remember also that all speakers have an RMS/AES rating and a peak rating which is normally double the RMS/AES. Given the stop start nature of guitar playing rather than constant music, there'll be times the speaker is taking more power than it's RMS rating and be still under it's peak.

So you have your ears and also the speaker rating that means you are unlikely to blow stuff as there is a bit of a built in safety with those two factors. But just in case and for those of us that do worry, our amps have a handy signal light. This lights up and flashes when the amp is dishing out enough power and the light gets stronger and solid the more power the amp gives. It will start flashing at 12.5% (-9db) of the amps rated power. So for a single channel of a GT800 (400w) in a 4 ohm load, that is 50w. At 8 ohms it's 30w and at 16 ohms just 15w. When the light starts staying solid the amp has doubled in power to 25% (or -6db because every 3db doubles the output). So our single channel now puts out 100w at 4 ohms, 60w at 8 ohms and 30w at 16 ohms. Below are a couple of charts showing the power levels at each impedance for when the lights flicker and are on solid (-6db and -9db). It should help give you one final "visual" safety net.

Chart showing output power at -9db (12.5%) with 0.775v input signal


  4 Ohms 8 Ohms  16 Ohms  Bridged 8 Ohms  Bridged 16 Ohms
 GT800FX 50w   30w  15w  100w  60w
 GT1000FX (1u &2u)  60w  40w  20w  120w  80w
 GT1600FX  100w  60w  30w  200w  120w

Chart showing output power at -6db (25%) with 0.775v input signal


  4 Ohms 8 Ohms  16 Ohms  Bridged 8 Ohms  Bridged 16 Ohms
 GT800FX 100w   60w  30w  200w  120w
 GT1000FX (1u &2u)  120w  80w  40w  240w  160w
 GT1600FX  200w  120w  60w  400w  240w

Chart showing output power at -0db (100%) with 0.775v input signal


  4 Ohms 8 Ohms  16 Ohms  Bridged 8 Ohms  Bridged 16 Ohms
 GT800FX 400w   250w  100w  800w  520w
 GT1000FX (1u &2u)  500w  320w  150w  1000w  650w
 GT1600FX  800w  500w  250w  1600w  1040w

Do I turn the modeller up full or your amp?

Ok this links back to the last couple of questions.

Solid state amps are basically attenuators. 

That means that to achieve full power at it's specified load our amps require a signal of .775v (0db) and the volume knobs up full.

If you put a higher level signal into the amp, it will achieve it's full power rating earlier than at full volume position and inversely, if you put a lower level signal in, say -6db, the amps full volume will always be -6db of full power rating.

If your volume is lower than expected even with the Matrix amp on full then look to increase the signal level going into the amp.

This could be the individual patch volume or the master volume of the unit or indeed the send level of a preamp.

Be aware of the noise floor of a unit as well. Turning something up full will usually turn up the amount of noise the unit generates. The Matrix amps are obviously designed to be turned up full and have a low level of noise/distortion but you may experience issues if you turn up the signal being fed into the Matrix too much and have the volume of the amp set too low.

You may have heard that the Matrix amps "come alive" at a certain level. A lot of players think this is something within the amp but in effect it is just the volume level and the physical properties of that volume (air movement, speaker interaction etc).

NOTEThe newer Axe FX units have a -10db and +4 db setting so you will find that -10db may be too quiet. +4db is ok but remember the amp will get to full power before the volumes are up full unless your patch levels are at a lower level or your global EQ level is reduced by -4db to compensate.

Do I have to connect a speaker to both outputs of the amp?

NO. Unlike tube amps which may be damaged by having no load (speaker) attached, solid state amps are perfectly fine having nothing connected to them. The rack amps we do are two mono bloc amps in one casing so in effect two separate amps in one box. It is fine to just use one channel and run the other with nothing connected. The only "kryptonite" for solid state amps is generally linking or shorting the two channels together either by plugging one output into the other or linking via a speaker that is not truly stereo and separated. If in doubt run mono and just use one channel.

It's perfectly safe running one channel with no load attached on the other.

My cab has two sockets on the back does that mean it is stereo and I can connect both channels of my amp to it?

Just because your cab has two speakers and two sockets on the back it doesn't mean it is stereo!

A lot of cabs have a second socket to link another cab to that one and change the impedance, called daisy chaining. Generally these will be unmarked sockets. Orange cabs are well known for this as are some Mesa cabs (usually marked as common ground on the back plate).

Single speaker cabs are never stereo (think about it folks) and we've come across people hooking up our amps in stereo because they had two sockets on the rear! Doh!

Marshall backplates that are switchable are usually ok if they are in the correct stereo position (the mono switch though will turn the second input into a daisy chain though so beware).

Never trust rehearsal room cabs and rider cabs or any strange cab that may look stereo. Unless you know the wiring or the switching is ok it is just safer to run in mono to the cab and avoid damaging the amp.

Tube amps don't mind having their transformers shorted out but most solid state amps will be damaged. If in doubt run mono. In all seriousness, unless you are using panning or ping pong delays, you won't miss stereo much given the small distance between speakers in a guitar cab.

What order of powering up should I follow?

So in general when switching on, the amp should be last in the chain. So preamp or modeller first and any effects etc and then the amp. You may still hear a pop as the amp powers up (when connected to a speaker) but this will be less than the sound of your connected stuff switching on if the amp was on first. When powering down, amp first then connected stuff to avoid the above in reverse. ON-Amp last....OFF-Amp first

A small thump or pop is normal and should not damage your speakers in any way.

Can I hook up different impedance cabs to each output?

Yes that is no problem whatsoever. So long as the load on each channel does not go below 4 ohms you are fine. So for instance a 16 ohm cab on channel A and an 8 ohm cab on channel B is fine. Or 4 ohms on one channel and 8 on the other is fine also. Remember each channel is in effect a separate amp so the 4 ohm rule is for each channel not the total for the whole amp.

What cables should I use?


So plenty of info here for you if you are unsure. To connect to the amp from your source (modeller, preamp whatever) you can use either a good quality instrument lead, or an XLR. The amp has combi inputs that will accept both. If the unit is in a rack then a short instrument cable (around 12" or less) will give you the same RF shielding as an XLR. For really long cable runs XLR's are best for their shielding properties but good quality guitar leads may just be a good for medium runs. If say you use a floor based effects unit, and run cables to the rear of the stage to the amp, you may well find guitar cables do the job. If you get hum or interference, then a swap to XLR's may help.

From the amp to a non powered (passive) cab you will need a speaker cable. We'd recommend trying to move to a Speakon connector where possible on the speaker cable. Normal guitar 1/4" jack speaker leads will of course work (as the outputs are also combi sockets). There are some limitations and caveats with this though.

If you do use 1/4" to 1/4" speaker leads best practice is to power down the amp before making any connections or plugging the speaker leads in or out (just like you would on a tube amp). This avoids any possible shorting of the tip and sleeve of the jack (however minimal) and is also safer as the amp could carry voltage to the jack if there is a signal present. Given the large voltage our amps carry it's worth it.

Speakons are much safer, robust and easy to maintain (solder-less connections usually). Nothing fancy is needed so avoid the gimmicks like gold plating etc. If it's generally good enough for sound reinforcement use (PA and front of house) it will be ok for use from the amp to cab. Nothing too heavy duty either is needed. Speaker cable around the thickness of a standard pencil should do and it doesn't need to be too long. Most good music store chains carry a range of PA stuff and a shorter length speakon lead to either speakon or 1/4" will do if you want to go down that route.

Powered speakers and monitors you need an instrument lead or XLR to connect to direct from your modeller. In that situation the speaker has it's own amp built in and doen't need our amp to do the job.

Input to Amp - Instrument lead or XLR

Amp Output to Cab - Speaker Lead 

When I play the signal lights on the amp are not flashing. Is this ok?

If you are playing at home or at lower volume and the lights don't flash, so long as the volume is loud enough for you then it's ok. All it means is that you are using less than the required wattage to light the signal levels. So long as the volume is loud enough for you, fine!


Can I play bass or extended range instruments through your amps?

Yes you can but obviously it will depend on how loud you need to be and what amp you want to use. Remember we have our GT1600 amp which is "aimed" at bassists and those who need the extra power when running large wattage cabs or on big stages etc. For those of you who play bass or 7 or 8 string guitars at medium sized gigs, then the GT1000 2U is probably a better choice over the 1U because of the larger fan and bigger heatsink for extra cooling. (bass frequencies require more power so the amp will be working harder). The GT1000 1U and GT800 1U will be ok for small gigs and where you don't need massive amounts of volume. For the low end stuff, if in doubt always go for the extra power as it is better to have it there and not use it rather than not have it when you need it!

What is the difference in sound between the GT800 and GT1000 amps?

Not so much a difference in terms of how they sound but how they feel. It is very subtle and is difficult to get across via audio or a video. The best way to describe it would be that the GT800 is a little more "compressed" or "tighter" sounding in the low mids region of the amp. The GT1000 is more open hence the "looser feel" and "more open sounding" descriptions we use. Volume wise there isn't a huge difference. The GT1000 has a little extra headroom in wattage at 16 ohms from the extra power though. In terms of which is best for your style of music, well we have players of various styles using both amps but perhaps those interested in tighter more modern metal sounds may favour the GT800 due to that extra compression we mentioned.

Do I need to have the amp in a certain spot in my rack due to heat?

Simple answer is no. Under normal conditions you'll probably find the modeller you use will get warmer than our amp does so it doesn't necessarily need to be on top or for better heat dispersion or whatever. So long as the front panel and rear fans are unblocked the amp should get enough airflow to remain cool. Often, placing in the bottom of a rack it will allow you to keep the feet on the amp as there is a small gap. Your choice wherever it looks nice!

I've heard the fans are loud on the 1U amps. Is this true?


They are loud to some people. On the very first models of GT amps we used a different model of fan. Unfortunately the manufacturer discontinued this model and we had to change to the current one we are using now. This model is louder than the older one but does have a better throughput of air so the amp has better cooling. We're using the best spec available so it isn't viable to use a quieter fan as the airflow is crucial to how the amp operates. Volume wise it is noticeable, kind of like a desktop PC running or a tube rack power amp. Generally when playing you'll not notice it but if a quiet environment is a must for recording or playing then certainly opt for the 2U GT1000 we do. That is near silent in operation.


We hope that answers some of your questions. There is some more info in the manuals but if you need any further help contact