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Clipping / Distorted using 4 CM


MayPRS
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So Saturday was my first gig with the HX Effects. Tested at home with no issues, great sound and good results so I was pretty confident taking it finally to a gig.

 

I connect with 4 CM like this:

 

  • Guitar -> OD/DS pedal -> HX Effects input
  • HX Effects Send -> VOX AC30 input
  • HX Effects Return -> VOX AC30 FX Loop Send
  • HX Effects L Output -> VOX AC30 FX Loop Return

 

I used a "4CM..." factory preset as base to add my blocks. First block in the chain is the Noise Gate (which takes the noise out my OD/DS pedal). I also use the Noise Gate volume in the snapshot to add a "solo" boost (0 db for rhythm, + 3db for solo snapshots).

 

As I turned the amp up at gig volumes (at home it was impossible to do so) - especially on the "solo" snapshots I can hear a non musical distortion like the amp (or the HX) are clipping. As the gig went on the amp also started to "stutter" (volume drop then came up again) which I suspect might be related to this. 

 

I think the FX Loop block is clipping. Any experience in such an issue? How do you solve it? FX Loop block is with 0 db at Send and Return. Should I turn it down?

 

Many thanks for any help!

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The difference between home and gig is the volume increase in the amp. Following the signal chain routing, that suggests that the clipping is occurring after the amp’s FX Loop Send. I would follow the signal chain from that point on. The clipping could be occurring in the HX FX Return block or in any following block in the HX FX.
 

Use the HX FX Output block which shows the output signal level either green (no clipping) or red (indicates clipping). You will need to do this at gig volume to trace the actual offending block(s). Start by checking the Level parameter of each block. Any block with a Level of greater then 0db could theoretically be causing clipping at the input of any following block. Set the Level parameter of all blocks to 0db and see if the problem persists. This will probably affect your tone, so the exercise will be to adjust the Level setting of the various blocks (some may need to be set to a minus-db level) in order to reproduce the tone without clipping. 
 

And have fun!

 

…. addendum…. The problem could still be occurring in the HX FX blocks before the FX Loop, so if the above is not working well repeat this approach with those blocks. For instance, if your external OD box, or any HX FX block, is sending a signal that is too hot the clipping may not become apparent until you crank the amp.

 

The overall issue here is called gain staging, and is important during preset creation. Every time a block is added to the signal chain there is an opportunity to cause downstream clipping. That’s why it’s best to create your presets at gig volume. I know that’s not practical for you but it does mean that your clipping issues will only be encountered at your gig.

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On 4/19/2022 at 9:16 AM, MayPRS said:

As the gig went on the amp also started to "stutter" (volume drop then came up again) which I suspect might be related to this. 

 

So - it was not related to this, just a terrible coincidence. This happened to me in the past and so I went and check the RCA cables inside the amp, as this caused the same symptoms in the past... and voila... nothing to do with the HX Effects this particular issue:

 

zOyUh1Y.jpg

 

Still have to figure out the clipping / distortion. :)

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Are you turning up the channel volume or master volume? 

If you're turning up the channel volume, you're increasing the signal that gets send out of the FX loop and probably distorting the HXFX return with a signal that's too hot.

If you're turning up the master, you're probably running out of clean headroom in the power amp section of the AC30 and clipping there.

 

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On 4/20/2022 at 10:27 PM, 52dmk said:

Are you turning up the channel volume or master volume? 

If you're turning up the channel volume, you're increasing the signal that gets send out of the FX loop and probably distorting the HXFX return with a signal that's too hot.

If you're turning up the master, you're probably running out of clean headroom in the power amp section of the AC30 and clipping there.

 

 

Thanks for the reply. Channel volume. Do you think I need to adjust the FX loop volumes?

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On 4/26/2022 at 3:58 PM, MayPRS said:

 

Thanks for the reply. Channel volume. Do you think I need to adjust the FX loop volumes?

You could try changing the loop level selector on AC30? What's it set at now?

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Could it be due to the fact that I'm using the first block (Noise Gate) with +3.0 db to boost for solos? 

 

What is the best method to raise volume for solos (in a snapshot)? A "level" block at the end of the chain? This would raise FX loop volume right? Before the HX Effects my previous pedalboard (a G-System) was used in 3 CM (only in FX Loop) and when I boost for solos, it would raise (of course) the FX Loop volume. Never had clipping/unwanted distortion with this method. 

 

Many thanks in advance.

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On 4/29/2022 at 4:22 AM, MayPRS said:

Could it be due to the fact that I'm using the first block (Noise Gate) with +3.0 db to boost for solos? 

 

What is the best method to raise volume for solos (in a snapshot)? A "level" block at the end of the chain? This would raise FX loop volume right? Before the HX Effects my previous pedalboard (a G-System) was used in 3 CM (only in FX Loop) and when I boost for solos, it would raise (of course) the FX Loop volume. Never had clipping/unwanted distortion with this method. 

 

Many thanks in advance.

I tend to use a Gain block for a solo boost. If I want just the volume boost I place it at the end of the signal chain. If I want it to also affect the tone I put it before the amp or a specific pedal.

 

Never tried using the Noise Gate.

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On 4/29/2022 at 12:43 PM, silverhead said:

I tend to use a Gain block for a solo boost. If I want just the volume boost I place it at the end of the signal chain. If I want it to also affect the tone I put it before the amp or a specific pedal.

 

Never tried using the Noise Gate.

 

Thanks. I didn't had the time yet to test as I've been on mini-holidays but I suspect the Noise Gate (+3b for solo boosts) might be the problem as I don't experience the issue when using the "rhythm" snapshots where the Noise Gate is at 0db.

 

I will try it today to see if that's the problem.

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So... it was just all a terrible coincidence... besides the amp RCA cable shown in a above post caused the stutter on the amp, the clipping/distortion was caused by one of the cables connecting the HX to the amp FX Loop. The cable was malfunctioning (a broken wire inside the jack) thus causing the distortion/clipping.

 

I now use two new cables for the amp FX loop and yesterday had a problem free gig! Great sound - now I just have to balance some of the presets in terms of volume for boost/solos - sometimes the snapshot with delays in it seem to be not as loud as it should be. But other that this small issue (unnoticed by bandmates or audience) but that I feel is not perfect yet, the gig went flawlessly. Ah on a curious note: I had a G-System and I thought the preset change was gapless... man with the snapshots I now realize what is really gapless! I have now to get used to only press the switch on the time I really want to kick in a harmony or something (on the G-System I pressed it some seconds early). I still have the habit of press it some seconds early and, on harmonies for instance, it kicks in a bit sooner that I want. 

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