My Gx_head_amp recordings get "fried" no matter what I do

All your LV2 and LADSPA goodness and more.

Moderators: MattKingUSA, khz

Post Reply
Nachei
Established Member
Posts: 235
Joined: Fri Feb 17, 2012 3:32 am
Has thanked: 6 times
Been thanked: 27 times
Contact:

My Gx_head_amp recordings get "fried" no matter what I do

Post by Nachei »

Hi, firstly a clarification, by gx_head_amp I mean the Guitarix module that usually goes connected to gx_head_fx... (I've seen that there's another project called gx_head that works as standalone).

Here is my case: I try to record gx_head_amp into a DAW (I've tried: Reaper, Ardour, and also Audacity, all with the same results), and the recording gets "fried". Absolutely clipped, even if all my levels are one step away from silence. If I put the guitar's knob to 0, play a note, and then start rising the knob, the moment the sound kicks in, the recording clips at +18, +24dbs, depending on the Guitarix preset I'm in.

The same happens with my interface's "Inst" knob. The moment I move the knob from 0 to something, the moment there's a slight sound, the recording peaks at around 18 to 24dbs. (I've tried in 2 interfaces, also with the same results: Lexicon Alpha and Samson Gtrack)

This happens also just the same even when I make Guitarix output volume zero. It just doesn't seem to affect the outcome...

It's been a while since I tried to record gx_head_amp, but I don't think this was the expectable behavior, is it?

I asked at the Guitarix forum yesterday, and someone there helped me testing different levels. By putting all the knobs at "noon" position, we got the track to stop clipping, but, I only discovered it later, the sound you get with that is unusable, as those knobs not only affect how "hot" the track is, but also are in charge of defining the sound...

I've also tried using a different guitar, and the results are always the same...

Another strange thing is that if, using the same parameters that "fry" Gx_head_amp, I try to record Gx_head_fx, it gets recorded correctly, at very conservative levels...

Anybody have an idea of why could this be? It's driving me bonkers... Thank you.
Last edited by Nachei on Fri Oct 26, 2018 1:29 pm, edited 1 time in total.
User avatar
lilith
Established Member
Posts: 1698
Joined: Fri May 27, 2016 11:41 pm
Location: bLACK fOREST
Has thanked: 117 times
Been thanked: 57 times
Contact:

Re: My Gx_head recordings get "fried" no matter what I do

Post by lilith »

Nachei wrote: I asked at the Guitarix forum yesterday, and someone there helped me testing different levels. By putting all the knobs at "noon" position, we got the track to stop clipping, but, I only discovered it later, the sound you get with that is unusable, as those knobs not only affect how "hot" the track is, but also are in charge of defining the sound...
If it was yesterday on IRC that was drwhat and me. Can you post some screenshots of your jack connections and the Guitarix rack you are using?
Nachei
Established Member
Posts: 235
Joined: Fri Feb 17, 2012 3:32 am
Has thanked: 6 times
Been thanked: 27 times
Contact:

Re: My Gx_head recordings get "fried" no matter what I do

Post by Nachei »

lilith wrote:If it was yesterday on IRC that was drwhat and me.
Yes, it was, and yes you were... :) Thank you for giving it a try (I wrote "forum" by mistake before, I meant the IRC)...

This is my Guitarix setup, it's just the Nuclear/Standard preset, with the output volume lowered to 0:
guitarix_preset.jpg
guitarix_preset.jpg (116.2 KiB) Viewed 1111 times
(The problem however happens just the same no matter what preset I use)...

These are my connections in Carla...
connections_reaper.jpg
connections_reaper.jpg (68.9 KiB) Viewed 1111 times

And this is the result I get, just by playing one random guitar note (it once peaked at +30db!), even with all the levels I can think of just one step away from silence...
reaper_clip.jpg
reaper_clip.jpg (12.01 KiB) Viewed 1111 times
On the other hand, when I record Gx_head_fx with the same settings, it does not clip, and the signal is even very low (shouldn't it be through the roof due to the high levels arriving to it from Gx_head_amp?).

Anyways, any idea or suggestion is welcome, this is borderline poltergeist and has been crippling me for weeks...
Last edited by Nachei on Fri Oct 26, 2018 1:27 pm, edited 1 time in total.
User avatar
lilith
Established Member
Posts: 1698
Joined: Fri May 27, 2016 11:41 pm
Location: bLACK fOREST
Has thanked: 117 times
Been thanked: 57 times
Contact:

Re: My Gx_head recordings get "fried" no matter what I do

Post by lilith »

Not yet sure, but can you make the connections like here and check again? I checked it here and there's a 25 db difference. So first you go into the Head_AMP and then into the HEAD_FX! In any case your connection is not the way it should be ;)

Image
tramp
Established Member
Posts: 2335
Joined: Mon Jul 01, 2013 8:13 am
Has thanked: 9 times
Been thanked: 454 times

Re: My Gx_head recordings get "fried" no matter what I do

Post by tramp »

Hi

I guess the problem is here the Output Gain setting. The Scala on the right in the amp module. This controller set the output volume of the Stereo Rack, so called gx_head_fx. As I see in your screenshot, it's set to -50db.
Whereas the Pregain and the Master gain set the volume in the mono rack, hence the volume diff between the output of gx_head_amp and gx_head_fx.

The connection between gx_head_amp and gx_head_fx was never meant as "output port", this been made as "effect loop ", so that you could insert external effects, or, your hardware amp.
You'll be much better of by recording the output of gx_head_fx.

Other then that, newer versions of guitarix comes with internal recording modules, those have level meters, clipping indicators and volume controls, those allow you to record at any stage in the rack without clipping.

regards
hermann
On the road again.
Nachei
Established Member
Posts: 235
Joined: Fri Feb 17, 2012 3:32 am
Has thanked: 6 times
Been thanked: 27 times
Contact:

Re: My Gx_head recordings get "fried" no matter what I do

Post by Nachei »

Thank you for replying. Could you answer me this simple question?: if you try to record Gx_head_amp in your DAW, does it clip to +18db minimum? In other words, is that expected Guitarix behavior, or it's just me? From what I gather you are somewhat involved in Guitarix development, so your answer would be very valuable to me...
Last edited by Nachei on Fri Oct 26, 2018 1:26 pm, edited 1 time in total.
tramp
Established Member
Posts: 2335
Joined: Mon Jul 01, 2013 8:13 am
Has thanked: 9 times
Been thanked: 454 times

Re: My Gx_head recordings get "fried" no matter what I do

Post by tramp »

It depends on the plugs you've loaded and the settings you've set.

In the image you've posted, you've set "Pregain" to 20, which means +20db. You've set "Master gain" at 8.7 which means again +8.7db
Expected gain level at gx_head_amp will be ~+20db (due to some non-linear algorithms working in the back) so yes, digital clipping in the DAC could be expected.

When you set the "Pregain" and the "Master gain" to 0, and ain't involve any plug, the output level at gx_head_amp should be normal. If not, something is fishy in your installation.

Other then that, on top of the rack you've the "mono level out" control, therewith you could reduce it as well to a acceptable level.
On the road again.
Nachei
Established Member
Posts: 235
Joined: Fri Feb 17, 2012 3:32 am
Has thanked: 6 times
Been thanked: 27 times
Contact:

Re: My Gx_head recordings get "fried" no matter what I do

Post by Nachei »

Ok, so I guess that replies my question: Gx_Head_amp gets "fried" the moment you take knobs beyond zero... This creates me a doubt:

Guitarix mimics analog amps.

Analog gear does not clip at 0db.

However, from your reply, one would say the gx_head_amp db values get transferred "as is" to gx_head_fx.

So whenever any knob is higher than zero (as in my screenshot, and please notice it is the screenshot of a preset I just downloaded, the knobs all came with those high levels), you are passing clipped signal to the next element in the chain (gx_head_fx). Isn't that a no-no in digital recording?
Last edited by Nachei on Fri Oct 26, 2018 1:26 pm, edited 1 time in total.
tramp
Established Member
Posts: 2335
Joined: Mon Jul 01, 2013 8:13 am
Has thanked: 9 times
Been thanked: 454 times

Re: My Gx_head recordings get "fried" no matter what I do

Post by tramp »

Nachei wrote:So whenever any knob is higher than zero (as in my screenshot, and please notice it is the screenshot of a preset I just downloaded, the knobs all came with those high levels), you are passing clipped signal to the next element in the chain (gx_fx). Isn't that a no-no in digital recording?
No, when all knobs been at zero, almost the input level will be transferred to the output.
And no, why? In digital (and inside jack) any value below FLT_MAX is valid without clipping. Clipping appears when the DAC (sound-card) convert digital values to analogue.
In guitarix we use the full range to work with. At least, when output to the sound-card, the max value should be 1.0 (gx_head_amp, is just a stage inside guitarix)
Imagine, what would happen when you take the signal somewhere inside your amp and connect it to your cabinet, inside the amp you may have 350V.

As you pointed out yourself, when you record the output from gx_head_fx, the level is correct.
On the road again.
Nachei
Established Member
Posts: 235
Joined: Fri Feb 17, 2012 3:32 am
Has thanked: 6 times
Been thanked: 27 times
Contact:

Re: My Gx_head recordings get "fried" no matter what I do

Post by Nachei »

Thank you both for replying

@Tramp:

Ouch, your reply outsmarts me and leaves me k.o. on the floor from the second line. I had it coming for asking, but hey, I had to try. Thank you for taking the time to explain, in the parts that I don't get I'll take your word for it... ;)

This is the thing with this forum (with all forums that are so diverse and universal, I guess). There is a mismatch of skills, and a lack of context, between the people who talk. I'm just a musician who got into Linux looking for an alternative to corporate abuse... but the tech stuff will never be my cup of tea; my "Power" bar depletes quickly when dealing with this stuff (and yet I can be playing and composing for hours without end...)

In case you wonder, my wanting to record Gx_head_amp was not out of a "whim", but part of a bigger investigation of mine regarding my guitar tone; for some reason, my audio seems to contract the rarest diseases. It's like a karma thing...

Anyways, thank you for bearing with me, you've been very helpful. I'll leave Gx_head_amp alone.


@Lilith:

My inquiries with this post were about recording gx_head_amp. Only now that I see your answer I see that I've named things wrong, and maybe that has created a bit of confusion.

By: Gx_head I meant > Gx_head_amp

and

By Gx_fx I meant > Gx_head_fx

(After publishing this post I'll try to go back and edit all the mentions, to avoid mistakes for future readers).

The setup you propose, thus, firstly, is for recording gx_head_FX, therefore off-topic for this post. It also, if I'm correct, wastes half of the signal, (Gx_head_fx is stereo, but with your setup, with out_1 disconnected, you're only recording half of it). Also, it forces you to use the DAW's monitoring to hear what you're playing.

I've tried anyway and the sound you get wasn't bad, at least with the setup I was using. I may experiment with this setup in the future; despite the aforementioned limitations, it's great to have such a clearcut layout, with so little "spaghetti" laying around, unlike mine. (Also, you have cured me from a dyslexia of years I didn't know I had with Guitarix modules' names, so thank you!)

Thank you again both, and sorry for the error in naming Guitarix modules... :oops: :roll:
User avatar
lilith
Established Member
Posts: 1698
Joined: Fri May 27, 2016 11:41 pm
Location: bLACK fOREST
Has thanked: 117 times
Been thanked: 57 times
Contact:

Re: My Gx_head_amp recordings get "fried" no matter what I do

Post by lilith »

@Lilith:

My inquiries with this post were about recording gx_head_amp. Only now that I see your answer I see that I've named things wrong, and maybe that has created a bit of confusion.
I didn't see that part of your posting. My fault...
tramp
Established Member
Posts: 2335
Joined: Mon Jul 01, 2013 8:13 am
Has thanked: 9 times
Been thanked: 454 times

Re: My Gx_head_amp recordings get "fried" no matter what I do

Post by tramp »

Nachei wrote:Gx_head_fx is stereo, but with your setup, with out_1 disconnected, you're only recording half of it
Well, as long you ain't involve a stereo modulation plugin like Chorus,Flanger or Phasor, both channels been identical, so recording only one channel will give you a proper mono signal, the same as if it was just one mono channel, not only a half channel or signal.
At least, a stereo channel consist simply of two mono channels.
On the road again.
Nachei
Established Member
Posts: 235
Joined: Fri Feb 17, 2012 3:32 am
Has thanked: 6 times
Been thanked: 27 times
Contact:

Re: My Gx_head_amp recordings get "fried" no matter what I do

Post by Nachei »

tramp wrote: Well, as long you ain't involve a stereo modulation plugin like Chorus,Flanger or Phasor, both channels been identical, so recording only one channel will give you a proper mono signal, the same as if it was just one mono channel, not only a half channel or signal.
At least, a stereo channel consist simply of two mono channels.
That's a very critical piece of information for me; I've always found a lot of information on how to configure Guitarix to play, but not so much on how to record it. On the other hand, the usual recommendation you find about recording guitars is recording them in mono, to make your life easier during mixing... but at the same time, given that Guitarix's output is stereo, it always felt "weird" to me feeding two stereo exits into one single mono track, I always wondered if I was doing it right... So this explains a lot and simplifies a lot my setup, thank you... :)
Post Reply