Where do you run your output knob on front of Axe?

[s0c9]

I think it's best to run a power amp pretty much full up and control volume from the pre-amp or mixer - exploits the maximum clean headroom of the amp. Depends I suppose on those sweet spots that you find sometimes - maybe the amp likes a hotter level at input meaning you have to wind down the output vols .... or there's a spot that sounds good in the amps volume setting that isn't full up. As long as it's never set low enough to clip or high enough to pop a speaker .....

Can't beat a good definitive answer huh?

LOL - depends on whether your amp is SS or Tube. For SS it's generally NOT best to run them "full up" - at least not into a cab, and not without gain staging them first. These knobs on the front of a power amp are NOT volume controls, they are input attenuators. Turning them full up or at minimum does NOT stop the amp from reaching its rated (continuous) power output levels. What they do is control the amount of input voltage required to drive the amp to rated levels.

Also clipping does not occur at "low" settings. Clipping occurs when the amp is unable to meet output levels resulting from input voltage exceeds the maximum supported by the amp and generally occurs when driving them too hard. This most often happens when your amp is not LARGE enough to handle the expected output. Rule of thumb is that a power amp should be able to produce from 1.5 -> 2.25x the continuous/program/rms rating of the speaker. For a 300w 8-ohm speaker, to handle transients, your amp should produce between 450 -> 675w at 8-ohms. You should not blow ("pop") or clip anything with that range amp. You should then gain-stage the amp (search the forum pls.. I provided detailed post on it some time ago) so clipping does not occur. That point is where the knobs should end up on the amp when done. That might be considered the "sweet spot".

I seldom use Tube power amps as they color the sound and have a different gain-staging process.

 

[maxdown]

Oh well ... doesn't matter ... I play trumpet

This might be the post you refer to? From searching your posts I think you might have to have "The knobs on your power amp are NOT volume controls" on your tombstone

OK.. lets clarify something right here.. .
The knobs on your Carvin amp are NOT volume controls. They do NOT control how many watts get sent to your speaker. They are INPUT level attenuators. Meaning.. setting them at a value determines the input voltage level required to drive the amp to full output power... IOW - amp sensitivity. When wide open, it takes less input signal to reach rated power, when almost off, much more signal level is required. The amp can generate FULL output power with the knobs at either position.
You need to "gain stage" your system. There are a number of ways to do that.
You do that in the following manner for solid state amps.
1. disconnect your speakers from the Carvin amp.
2. turn down output levels on Axe-fx and set the knobs on the Carvin to zero or off.
3. Adjust input level on the Axe per instructions
4. Turn the Axefx output level (out1 if connected to amp via OUT1 jacks) up FULL.
5 . While playing.. slowly turn up the input level knobs on the Carvin until the clip light on the amp starts to show.
6. Now, back down the amp levels (knobs) a notch or two.
7. Turn OFF the axe output level and reconnect the speakers to the Carvin.

Now you are correctly gain staged. You will never clip the Carvin amp, even if the Axe is [accidentally] cranked to full output levels.
You can now control the "volume" level of your rig from the Axe OUT knob, and never need to touch the Carvin levels again.
Of course, 50% output level on the Axe could get REAL LOUD, but your signal chain will be set correctly wherever you decide to set that level.
Adjust to taste.

Hope this helps.

 

[chris]

so what you're saying is.... the knobs on a SS power amp are not volume controls that adjust the amount of wattage coming out of the amp?! WHEN DID THEY CHANGE THAT?!

 

[s0c9]

Oh well ... doesn't matter ... I play trumpet

This might be the post you refer to? From searching your posts I think you might have to have "The knobs on your power amp are NOT volume controls" on your tombstone

At least I'll be remembered for something

 

[s0c9]

so what you're saying is.... the knobs on a SS power amp are not volume controls that adjust the amount of wattage coming out of the amp?! WHEN DID THEY CHANGE THAT?!

They've been that way for as long as i can remember using them. Folks treat them like volume controls, and no they do NOT control output wattage.
Let's say you have a "stereo" (2-chan) SS power amp that produces 1000w from each channel at 8-ohms. With the "volume" knobs wide open, there's little input signal attenuation and the amp can reach rated output (1000w) fairly easily. With the knobs almost "off" (full attenuation) you can STILL cause the amp to output 1000w - it depends on the input signal level. The knobs do not affect that capability. IOW - you do not get 10w output at full attenuation and 1000w when wide open.

This is a common misconception, and has caused many blown speakers and thermal shutdowns due to clipping. That's why it's a good idea to use brick-wall limiters if they have them built into the amp. most "pro" amps do these days. If not, put a compressor ahead of the amp, and you can run it wide open.

 

[Phostenix]

This is the whole job of this level and where others set it really does not matter IMHO.

No, but it is interesting to know what others do. I thought it was odd that I run the level so low into my powered monitors & FOH. It's good to know that lots of other people end up setting their output level at 9 o'clock, too.

 

[s0c9]

No, but it is interesting to know what others do. I thought it was odd that I run the level so low into my powered monitors & FOH. It's good to know that lots of other people end up setting their output level at 9 o'clock, too.

It should depend on what FOH wants. The Axe puts out a line level signal from OUT1. if the FOH console does not have a line-in switch/input, then you will barely need any level on the Axe, and FOH may have to pad it also.

Output levels depend on what you are going into. The rule should ALWAYS be to maximize your signal level without clipping, thereby keeping a low noise floor. Noise=BAD! For example, if you have the monitor level up and the signal from the Axe out fairly low (8-9), then you will get lots of noise (hiss, buzz, etc) from the monitor as the input signal is not high enough. Solution is to turn down the monitor level and increase the Axe out level to taste.

For example, when playing guitar, I set OUT1 to about 9 (to FOH), and OUT2 to about 11 - to FRFR monitor.
When playing bass, OUT1 is about same, and OUT2 is [mostly] Wide Open - as it goes into a power amp and then into a bass cab.

 

[roodboy]

Originally Posted by Fractal Audio
Everyone listen and listen closely:

UNITY GAIN IS ONLY FOR WHEN RUNNING FOUR-CABLE METHOD. OTHERWISE, USE THE LEVEL CONTROLS TO CONTROL THE LEVELS. YOU SHOULD NEVER TURN THE LEVEL KNOBS ALL THE WAY UP UNDER NORMAL USE.
Anybody know why ?

 

[jon]

Originally Posted by Fractal Audio
Everyone listen and listen closely:

UNITY GAIN IS ONLY FOR WHEN RUNNING FOUR-CABLE METHOD. OTHERWISE, USE THE LEVEL CONTROLS TO CONTROL THE LEVELS. YOU SHOULD NEVER TURN THE LEVEL KNOBS ALL THE WAY UP UNDER NORMAL USE.
Anybody know why ?

this post from cliff hopefully clears it up:

Let me clarify, you shouldn't NEED to turn the output level all the way up and, in general, if you do, then your gain staging is probably suboptimal.

Unity gain mode is a special mode designed for use with the 4CM. When you turn the output levels all the way up whatever you put in you get out (assuming all unity-gain blocks in the chain). If you have an amp block in the chain then you have tons of gain and therefore no longer have unity gain.

Optimal gain staging would be with the level knob around noon. Higher than this and you risk clipping the inputs of the downstream device. With the level knob at full the Axe-Fx II will probably incinerate a Soundblaster or other low-cost stuff. The max level out of the Axe-Fx II is +20 dBu. Most pro gear can easily handle that but lots of gear cannot and the trend in newer gear is towards lower and lower maximum input levels (due to single-ended designs and low-voltage/low-power constraints). In the old days, +20 dBu was routine. Everything could put out and handle +20. Not so much anymore.

For a Strat, near 100% on the input level is not unusual. I run my Strat around there. It has vintage-type pickups.

 

[Thomas Larsson]

I would say that depends on have strong signal I need . It´s a volume controll I guess.
One time you might be feeding your phones and next time you are feeding a power amp.

Short answer : It has been at all positions .

 

[paulmapp8306]

On the SS amp Vol knobs - AFAIK they have ALWAYS been input attenuators - and that often leads to issues for those not understanding them.

A SS amp is rated at a max output, and its input sensetivity gives you the signal level required to reach that power. so - with the Matrix GT1000 for example - Its rated at 500W perchennel into 4 Ohms with an ip sens of 0db (0.775v). That means if you feed the amp a signal of 0.775v then the output into a 4 Ohm load will be 500w - HOWEVER, feed it a signal 6db less than that - the output will also be 6db lower - so 125w. It also means if you feed it a larger signal (and its capable of taking that signal without clippiong the INPUT stage) the output will also be larger. That would lead to output clipping with the Amps controls full up BUT, If the amps controls are set at - say 12 o'clock - and that equates to -12db attenuation at the input then you could feed tha amp an input signal 12db higher than 0.775v and STILL get the max 500w output.

I also dont see any reason why you cant run tghe AFX knobs up full - providing you dont clip the outputs of the AFX, or the inputs of the amplification device/desk.

What I have done is set the output of the AFX with the vol knobs up full with the gain slider in the global out, to such a point that with ethe Matrix also on full, its signal light is just flicking. Thats at -9db for the matrix and so equates to around 62 Watts (my speaker being rated at 60w). That would also indicate that the input signal is -9db from the 0.775v (odb) required signal to give the Mat rated OP - so its well within the AFXs capability to produce with no issues.

Incidentally - running a SS power amp at max with a low ip signal v running it low with a high ip signal makes absolutely no difference to its clean headroom. The headroom is dependant on the max power tha amp can generate - regardless of how that power is achieved. The only exception to that (as I stated earlier) is iof you clip the amps inputs.

Having said all that - If it was not a pain to use the AFXs output knobs (purly due to where my guitar cable routes into the front 1/4" socket) I would run the Matrix full and control volume from the AFX (still with the max OP regulated by the global OP gain control) - but currently its not.


Running the Matrix full id no differnt at that - from a headroom perspective - as running the AFX signal

 

[paulmapp8306]

WTF happend to that last line !!!

It should read - Running the Matrix full with a low input signal is no different - from a headroom perspective - as running the Matrix lower with a hotter input signal.

 

[Bodde]

flat out and control my volume from my Matrix.

Aren't you overloading the input of Matrix this way? Or is that not possible?
I was also thinking about this output level question lately (since I have the Matrix for a few weeks now). I have to adjust the output quit much because of different patch levels. Keep tweaking the levels of the patches a lot. Not sure whether I should adjust the output on the Axe or the Matrix for the best results? I run stereo so I have to adjust both A and B outputs on the Matrix so it might be more convenient to adjust the output on the Axe itself. Just not sure how it will affect the sound of the Matrix?

 

[paulmapp8306]

I guess its possible to overload the Matrix input if the Op from the AFX is too hot - but i havent managed that yet. As I say - I do have the global output gain set to -11db but thats to set max op of the Matrix where I want it. That gives around -9db on the Matrix. If that gain was set to 0db - so 11db hotter - I guess I could be overloading the Matrix Inputs if the AFX op knobs were set full up. Havent tried - and if I did Id blow my speakers first in all probablity.

 

[roodboy]

this post from cliff hopefully clears it up:

Thanks

 

[saroehr]

Thanks for posting that update. The documentation wasn't clear and as a new user I set it to 100%. I did have to then engage a pad on my mixer to lower the signal because it was too hot so that probably confirms the post. :shock

Thanks again!

 

[saroehr]

Thanks for posting that update. The documentation wasn't clear and as a new user I set it to 100%. I did have to then engage a pad on my mixer to lower the signal because it was too hot so that probably confirms the post. :shock

Thanks again!

 

[saroehr]

And apparently I have a problem repeating myself myself.

 

[Sebastian]

I repeat myself when under stress.
I repeat myself when under stress.
I repeat myself when under stress.
I repeat myself when under stress.
I repeat....

The more I look at it.... the more I like it

 

[jon]

LOLLLLL!!!!!

also remember that the mixer needs to be set to LINE level and NOT MIC level (common mistake)