Fixed Tube Pre Noise

The root cause is because you've got so little gain and then you're making it up with tons of gain after amp. You've got the amp block level control at +20 dB and then another +20 dB in the graphic EQ after the amp and then another +12 dB in the output block, etc. So you've got at least 52 dB of gain after the amp!!! And that's not including the gain you've got in the compressors.

Regardless, I've adjusted some things that will prevent it for the next firmware release.

Okay...this is not true somehow...something else weird going on? ...or not looking in the right place?
I imported the patch I linked to...same gain structure as the patch I did the test with...that I knew was the one I made the preset that I posted.

I analyzed the level adjustments at every stage of the patch:
input: 0dB
tube pre: 3dB
multi-band compressor: level 1: -2.5dB level 2: 0dB level 3: 0dB
graphic eq: 6dB...2.16dB max on certain bands[edited]
compressor: 6dB
both reverbs: 0dB...in parallel...6dB
output: 12dB

sorry...but it looks like 35.16dB[edited] not 52dB
...could i be reading this wrong?

edited to add the increase of 2 reverbs in parallel and the geq effect of certain bands peaked to 2.16max...to the tally...

additional edit: the gain imposed along the way feeding opto 2 = 11.16dB
 
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ok...but are you seeing the levels in these blocks as I am?
they said 20 in the tube pre and 20 in the graphic eq...how is that possible?

It doesn't matter. Fact is that there's a mismatch of levels.

TUBE PRE does not add a lot of gain itself. And you've dialed in a very low preamp level (1.99).
In fact, when the Amp block is bypassed, the signal is louder than with it engaged. That isn't good gain staging.

You're then adding gain at later stages (GEQ, Output block), which will increase noise.

You're also using wrong Mix/Level parameters in the parallel Reverb block, with increases the signal level and will increase noise.
http://wiki.fractalaudio.com/axefx2...vel_.2F_Input_Gain_.2F_Bypass_Mode_parameters

BTW the Level parameter doesn't tell everything about the level. For example, if you're boosting frequencies in the GEQ, the overall level increase will be higher than value of the Level parameter.
 
Thanks for the help, I really do appreciate it.

What I did not include was the eq settings and the added dual reverb levels.
But you are wrong to say "it doesn't matter" for a reason unaffilliated with this current thread.
What I was trying to say "nicely" was "Is there a bug in the importing of presets", because that would indeed matter. No?

But forgetting that, there is a problem yet unaddressed.
I am drawn, as well as many others to the tube pre, looking for a "clean" tube pre.
I HAVE to push the gain down to 2 to keep it from barking.
If I wanted distortion I would look elsewhere.

So, while it has been stated that my gain staging in the preset was inferior, noone has offered the proper path going forward. If I were to place a gain block before the tube pre, would I not be overloading the tube pre all over again? If that is the case, then what I have done on the back end of the tube pre to create a usable level cannot be questioned? If there is another path, I will be deeply grateful as I do love the sound of this amp block.
 
You're then adding gain at later stages (GEQ, Output block), which will increase noise.

just to complete the level story, here are the gain levels of the 8 band geq, left to right:
-5.28,-3.36,-2.40,-1.20,0.24,1.92,2.16,2.16,1.68,1.20
...as you can see, no gain above 2.16
 
thanks for the link...
...without so much as just saying it, the salient comment here on the level in parallel is to simply enter -3db for both blocks' output level?
You might want to re-read what he wrote:

You're also using wrong Mix/Level parameters in the parallel Reverb block, with increases the signal level and will increase

and what the wiki says:

With effects featuring an Input Gain parameter, keep Level at 0 dB and use Input Gain to dial in the desired amount of effect. Also, setting Mix at 100% avoids creating "double" direct signal paths, which result in undesirable increase of volume.

Not sure where you got -3db from...
 
Okay...I just figured something out here.
It is ONLY the interaction of the tube pre with the optical 2 compressor in this preset which is causing the peculiar noise artifacts and the synthesized zipper tail as the level decays....
...flip it out...noise gone....flip it in....there's the problem.
 
You might want to re-read what he wrote:



and what the wiki says:



Not sure where you got -3db from...
thanks for the tips sir...sorry i meant -6db not -3db
...but while this places the fear of god in me that i need to be careful with gain staging....inadvertently there is this interaction created with the opto 2, which is a recent addition...
 
Looking at the preset with FracTool (not in front of my Axe Fx), it appears that you have the Amp level at +3dB. You seem to be using other blocks to try and adjust for overall level. The amp block can go all the way to +20dB... use Amp block Level to adjust the overall level of your preset.

Also, it appears to me that you have the main Level control in the Output section of the preset at +12dB...

Regarding the discovery around the compressor, it may just be that the level added there is pushing things over the limit in the overall amount of gain being added.
 
yes thanks...these levels are annotated earler in the post.
i played with the output in the tube pre...with limited success...but i agree the levels could be better managed

i don't think there is too much gain going into the opto 2 though...from the levels before the block...maybe...i dunno
 
Looking at the preset with FracTool (not in front of my Axe Fx), it appears that you have the Amp level at +3dB. You seem to be using other blocks to try and adjust for overall level. The amp block can go all the way to +20dB... use Amp block Level to adjust the overall level of your preset.
....
Regarding the discovery around the compressor, it may just be that the level added there is pushing things over the limit in the overall amount of gain being added.
In retrospect, right or wrong, I was also worried about hitting opto 2 with too much signal.
 
I HAVE to push the gain down to 2 to keep it from barking.
If I wanted distortion I would look elsewhere.

That's weird because TUBE PRE doesn't really add distortion (edit: in the lower half of the range of Input Drive).
I tested it right now. I hear no added amp distortion when increasing Input Drive (edit: from 2 to 5).
What I do get when doing that, is output clipping (output level is too high) and that's easily dealt with.

So for proper gain staging I'd increase Input Drive.
 
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That's weird because TUBE PRE doesn't really add distortion.
I tested it right now. I hear no added amp distortion when increasing Input Drive.
Strange. I experimented with Tube Pre on an acoustic patch a few weeks ago. It added audible distortion. The sound guy commented on it, saying he didn't prefer it. I bypassed the Amp block, and the distortion went away. The preset was approximately leveled with my other presets at 0 VU.
 
Strange. I experimented with Tube Pre on an acoustic patch a few weeks ago. It added audible distortion. The sound guy commented on it, saying he didn't prefer it. I bypassed the Amp block, and the distortion went away. The preset was approximately leveled with my other presets at 0 VU.

Ah, I meant between values 1.99 (OP's) and higher such a 5.00.
 
I will test it again...but I am pretty sure on big block jazz chords I could get the tube pre to audibly distort well below 5...
 
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