The new MATRIX GT800FX. THE amp for THE Axe-Fx

DADA said:
Stefherbuel,

Congrats, you made a wise decision.

I hope you live in the US cause the waiing time in Europe for the II will be veeeery long if you have to wait for one :)

Regards
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thanks and yes i leave in europe g66 told me about 6-8 weeks waiting time ...
 
paulmapp8306 said:
By reducing the input sensitivity on the Gt800 - it just makes it respond better to those changes and makes it feel more valve like. For PA uise, you the XT is fine - for guitar use, the GT is better.
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You're saying that by decreasing poweramp input sensivity, you end up having to turn up the Axe-Fx output to compensate, correct? How does this make it feel more valve like?
 
No, that was my bad - the sensitivity is actually increased. The input signal required to produce the max rated output was reduced from +4dbu to 0dbu, but as i say thats actually an increase in sensitivity. Im not sure that makes it more valve like on its own - it wasnt the only tweeks (high and low Freq damping, and some other stuff was also changed), but it makes it react more like the reference VHT (not a goal in itself BUT the VHT is a very good and popular valve power amp) purely because that has a 0db input sensitivity.

When I first tried the XT800, I was trying to get the two amps to sound/behave as close as possible. Again not necessarily a final goal but my patches were tunes to the VHT. I found that EQ wise I could do that. It needed some changes but the VHT isnt flat - its flat for a valve amp but not flat - the Matrix is flat. What I was finding though was once I have tuned a patch to work on the Matrix it was great - then Id change guitar, of step on a boost and the two patches no longer responded the same. This was put down to the IP sensitivity. Basically as the signal strength changed, that extra gain or a change of PUs would cause, the two amps were reacting differently to it - because as a % of its required input the VHT was getting a greater increase. Its a small thing - but just helped get it close to the reference.

As I said it wasnt the only change, but the whole package is very nice.
 
Tonally nothing. the other mods do affect the tone - the HF and LF damping. It smooths off the highs, and takes some mud from the lows, but the sensitivity change is more to do with feel. Its subtle, but compated the the XT, the GT seems to be less stiff - have a little more bounce or give in it.

It does feel more valve like than a SS amp.
 
Quingcong, you may be better off getting the technical jargon from Andy at Matrix. All you'll get from us guitar players is waxing lyrical about how it sounds! However from the XT to the GT there is a noticeable difference, the GT feeling "looser".
 
paulmapp8306 said:
No, that was my bad - the sensitivity is actually increased. The input signal required to produce the max rated output was reduced from +4dbu to 0dbu, but as i say thats actually an increase in sensitivity. Im not sure that makes it more valve like on its own - it wasnt the only tweeks (high and low Freq damping, and some other stuff was also changed), but it makes it react more like the reference VHT (not a goal in itself BUT the VHT is a very good and popular valve power amp) purely because that has a 0db input sensitivity.

When I first tried the XT800, I was trying to get the two amps to sound/behave as close as possible. Again not necessarily a final goal but my patches were tunes to the VHT. I found that EQ wise I could do that. It needed some changes but the VHT isnt flat - its flat for a valve amp but not flat - the Matrix is flat. What I was finding though was once I have tuned a patch to work on the Matrix it was great - then Id change guitar, of step on a boost and the two patches no longer responded the same. This was put down to the IP sensitivity. Basically as the signal strength changed, that extra gain or a change of PUs would cause, the two amps were reacting differently to it - because as a % of its required input the VHT was getting a greater increase. Its a small thing - but just helped get it close to the reference.

As I said it wasnt the only change, but the whole package is very nice.
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I've been following your posts that state the more sensitivity=more valve feel and as an electrical engineer with experience in designing analog audio electronics I can state that:
More sensitivity=more voltage gain which in any modern circuit is a linear process(i.e. not dependant on level and within limits, frequency)

It is true that with a fixed open loop gain more closed loop gain results in lower High frequency roll off frequency but in any modern circuit designing a 50Khz roll off amp is trivial regardless of input sensitivity.

So please stop correlating input sensitivity with "valve" feel because it is misleading.

If something is special and tweaked then my bet would be a slower transient response through the design of the feedback loop that again has nothing to do with input sensitivity.

Still As others have mentioned , all AXE-FX needs is a linear amp both in frequency and dynamic response so that you can get all the valveness from the AXE.

I sincerely hope that the GT800FX is this kind of amp cause I have set my targets on it.
 
Im an Electronics Tech too :)

Still - you are of course right. The reason WHY the senstivity was changed was to bring it in line with the popular valve power amps, that tend to be spec'd at 0db. The difference in sensitivity meant that with an A/B test - what was similar with one setting was no longer similar with another. Hardly surprising, but that was why that setting was altered.
in feel.
there were other tweeks, including reducing the response - because the XT800 was very fast, and resulted in a hard edge to the sound. With the reduced response its spongier in feel. HF and LF dampng was changed too, the amp is still flat in guitar freqs, but rolls off a little above/below those freq which results in a smoother top end and less "full" in the bass.

As stated - to get al the Tech. talk to Matrix - they designed it after all, but needless to say the XT800 is very nice - the combined tweeks resulting in the GT800 make it nicer for use with guitar.
 
Hi,
I'm thinking of buying a gt500fx and Matt said that it is no problem. What do you guys think? My impression is that the gt800fx is overkill for usage with my 160 watt cab.

Cheers
PhillAnselmo

Ps: this amp is going to replace my v300 which has enough headroom for me. It's just the weight.
 
PhillAnselmo said:
Hi,
I'm thinking of buying a gt500fx and Matt said that it is no problem. What do you guys think? My impression is that the gt800fx is overkill for usage with my 160 watt cab.

Cheers
PhillAnselmo

Ps: this amp is going to replace my v300 which has enough headroom for me. It's just the weight.
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160w at what ohmage ? Bridged or running stereo? I'd say you'll be fine. The 500's 250 a side at 4ohms and about half that at 8ohms so you've got a bit of headroom.
 
PhillAnselmo said:
Hi,
I'm thinking of buying a gt500fx and Matt said that it is no problem. What do you guys think? My impression is that the gt800fx is overkill for usage with my 160 watt cab.

Cheers
PhillAnselmo

Ps: this amp is going to replace my v300 which has enough headroom for me. It's just the weight.
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Well it is what you say. If the weight, connectivity, sound and build quality meets your demands the extra wattage and or channel is for free :) And maybe in the future you will have a different setup with an extra cab for stereo.

Our bass player also uses just one channel because he likes the other specs and the sound quality of the amp.

So extra headroom for free:)

It is a great amp but that is mine experience.

Regards
 
My cab is 160 watt at 8ohm (bridged). So basically at lot of guys are running the gt800fx in stereo mode with just one channel? Probably it's not that much of overkill :) when the amp is driven that way. I thought of running it in bridged mode.
Matt said that they have worked on the fan noise and pop at startup. Has somebody received an amp with this modifications?
 
PhillAnselmo said:
My cab is 160 watt at 8ohm (bridged). So basically at lot of guys are running the gt800fx in stereo mode with just one channel? Probably it's not that much of overkill :) when the amp is driven that way. I thought of running it in bridged mode.
Matt said that they have worked on the fan noise and pop at startup. Has somebody received an amp with this modifications?
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In stereo mode you have two independent channels each with 250 Watts in 8 ohms It is no problem to use just one channel. I am using a stereo setup so I use both channels. Using the amp in bridge mode is indeed an overkill for a 160 Watt cab.

Nice to hear they not only listen to their customers but also integrate our ideas for futher improvement. Personally I have no problem with the small startup pop and the already low fan noise.

Maybe it is an idea to read the manual which you can download from the Matrix site.

Regards
 
PhillAnselmo said:
My cab is 160 watt at 8ohm (bridged). So basically at lot of guys are running the gt800fx in stereo mode with just one channel? Probably it's not that much of overkill :) when the amp is driven that way. I thought of running it in bridged mode.
Matt said that they have worked on the fan noise and pop at startup. Has somebody received an amp with this modifications?
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Bought mine a couple of months ago. Haven't heard anything from Matrix re; fan noise/ start up pop since then.
 
There were some questions here from users about the little pop. And some new customers had a question about the fan noise. Apparantly they decided to improve this for their next batch of amps. So the already silent GT800FX is now even more silent and plopless. And if this makes new cystomers more happy why not?
 
DADA said:
There were some questions here from users about the little pop. And some new customers had a question about the fan noise. Apparantly they decided to improve this for their next batch of amps. So the already silent GT800FX is now even more silent and plopless. And if this makes new cystomers more happy why not?
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How do you mean? My GT800fx is not plopless nor silent. So are you referring to future modifications of the Matrix GT800FX? Please clarify.
 
Got a notice today that my GT800FX will be delivered Thursday. :))
 
bufon63 said:
How do you mean? My GT800fx is not plopless nor silent. So are you referring to future modifications of the Matrix GT800FX? Please clarify.
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I am just translating the post from PhilAnselmo. If you want clarification sent Matt an email.

Got a notice today that my GT800FX will be delivered Thursday. :))
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Yek, this looks like an intense Matrix week.
Have fun!
 
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