The following table show the output power of the amplifiers, for different loads.
Signal lights starting to stay on = -6dB = 25% output power
Signal lights starting to flicker = -9dB = 12% output power
How flat is flat ? The following chart shows a response sweep of a GT1000FX into an industry standard resistive 4ohm load.
We have been asked some good questions over the previous months. The answers to a few of these are presented below. If you have a query that is not answered below please do send us an email.
Q1. How do I make a bridge cable to use the GT800FX in bridge mode ?
Q2. Do I have to connect a load to both outputs ?
A2. No, you can consider the amp as two mono amps whilst the mode switch is set to the stereo position. You can leave the second channel unplugged, or let your bassist play through it.
Q3. Do the loads have to be matched if I use both outputs ?
A3. No. You can connect a 16ohm cab to channel A and a 4ohm cab to channel B. The amp will work just fine provided you do not connect a load less than 4ohms to each channel, or less than 8ohms when connecting in bridge mode.
Q4. At what power level do the signal lights start to illuminate ?
A4. The LEDs will start to illuminate at -9dB, which for the GT800FX equates to roughly 50 watts into a 4ohm load, per channel. ( see Q7, setting power level below ).
Q5. Why is there is no grill over the fan at the rear of the amp ?
A5. Each of the fans has its own grill built in. The part you can see at the rear of the amp remains stationary. The blades of the fan are protected by this stationary grill.
Q6. How do I take the rubber feet of the bottom of the amp ( and put them on again ) ?
A6. The shiny plastic inserts inside the rubber feet are clips which hold the feet in. Carefully work a small flat blade screwdriver underneath the edge of the shiny plastic part and prise it outwards. The rubber foot will now come off. If you need to put the feet back on then pull the plastic insert out from the rubber slightly so the flanges/petals are closed by the rubber foot. Align back with the hole and push to pop back in.
Q7. How do I set the output power of the GT800FX using an Axe Fx to match the power of my guitar cabinet loaded with a v30 or similar?
A7. This question was answered well by Paulmapp8306 on the Fractal forums, I have copied his reply below;
“Matrix went with a signal light which flickers at -9db and remains on at -6db. That equates to 50W when flicking and 100W when stable into a 4 Ohm load, 30W and 60W into an 8 Ohm load, then 15w and 30w into a 16 Ohm load. While with a 16 Ohm load thats not much use – the Max OP is 130w anyway so should be safe for most 16 Ohm cabs. With 4 and 8 Ohm loads it was deemed more useable as it gives a guide of OP power at or around the powers cabs are more suited for while lesving enough headroom.
The light is very useable. Set the AFX up using the gain slider in the global out menu while both AFX and Matrix are up full ( with no speakers connected ) so the light on the Matrix flickers when playing your loudest patch hard (with any vol boosts engaged). At that point you know the power the amp is pushing into the speakers. Then raise the gain slider by however many DBs you need to provide the most power your speakers can handle. That way when both hardware vol pots are up full – your at the max volume your cabs will safely handle. from there you control your actual volume from the Matrix gain knob.
For example, if you have a 2×12 cab rated at 8 Ohms loaded with a pair of V30s, your max RMS power handling is 120w. Set the Gain slider of the OP connected to the matrix at its lowest (-12db) set the Matrix knob to its lowest and the AFX knob to its highest. Start playing and raise the Matrix knob to full (you can actually do this with no speaker attached with SS amps – so no danger of damaging your cab or blowing your ear drums during the procedure). If the light starts to flicker while raising the Matrix gain to full your patches are too hot – back off the patch gain. Once the Matrix is up full – go back to the global output menu and start raising the gain slider until the Matrix light flickers while playing. At this point your puttong 30w into your cab – if the light goes to permanantly lit quickly (from off) thats fine – it means you putting 60w into the cab – but your better off with the light flicking. So – now you know your at 30w. the cab handles 120w. Each 3db raise doubles the power – so raising the gain slider in the global out by a further 6 db will then push the full 120w into your cab (3 db up from 30w = 60w, then a further 3db up from 60w = 120w). At this point your set. Provided you use the patch as your “comparison” patch and dont make one thats louder – the max you can push with both Matrix and AFX front pannel knobs up full is 120w – which matches your cabs handling. If you get the odd spike more than that (possible if you play harder with the adrenaline of a gig) its not an issue – as guitar speakers can handle spikes above their rated power (the manufacturers know for example a 50w tube amp will push up to 80-90w when the power section is pushed hard – so take this into account).”
Q8. I am using a standard jack lead to link my GT amplifier to my speakers but it does not seem to be making a good connection?
A8. All Matrix amplifiers are made using Neutrik connecters. We believe they are the best quality available in the world. Where possible we ask our customers to use high quality leads made with genuine Neutrik connectors. The two pictures below show the differences between the connectors.
Q9. I have the gt1000 fx and the axe-fx2 in my rig does it matter which one is powered up first the gt 1000 or the axe fx 2 ? or vice versa?
A9. The normal way of thinking is amp on last, off first. The reasoning behind this is the amp will amplify whatever is ahead of it. Therefore if a piece of equipment up the signal chain makes an unexpected loud noise as it turns on, you dont necessarily want to send that to your speakers.
Likewise first off, to stop any any wanted signals getting amplified as you turn the other equipment off.