Crosstalk / Feedback Issue

[avalanchis]

Hello,

I’m experiencing a similar problem to what is described in this thread:

https://www.eventideaudio.com/community/forum/stompboxes/feedback-loop-possibly-cross-talk-issue

I am trying to use my H9 in Pre/Post mode, but I am getting a lot of what sounds like crosstalk or feedback when I engage the loop on my amp (which is an Atomic Amplifire).

Here’s how I have things routed:

Guitar -> H9 Input 1

H9 Output 1 -> Amp Input

Amp Loop Send -> H9 Input 2

H9 Output 2 -> Amp Loop Return

The input meter is showing about -25 for both channels.

I’m using a phaser algorithm preset which is set to “PRE”.  

My understanding is that channel 2 on of the H9 should be passing an unchanged signal through, but when I engage the loop on my amp, I get a high-pitched squealing feedback sound.

I’ve tried using different cables and different guitars but this doesn’t seem to affect the issue.

Please let me know what I can do to resolve this issue.

Thanks!

Alan

[wedelich]

Your understanding is correct.  If the H9 is in Pre/Post mode and your preset is set and saved at Pre, H9 i/o 2 should pass the signal unchanged.  A few questions to get started: 

1. Is your amp's loop serial or parallel? 

2. Does this occur with any other algorithms on H9, or is it exclusive to Phaser? 

3. Is the feedback a quick burst, or is it just constant once you engage your loop? 

[avalanchis]

wedelich wrote:

Your understanding is correct.  If the H9 is in Pre/Post mode and your preset is set and saved at Pre, H9 i/o 2 should pass the signal unchanged.  A few questions to get started: 

1. Is your amp’s loop serial or parallel? 

2. Does this occur with any other algorithms on H9, or is it exclusive to Phaser? 

3. Is the feedback a quick burst, or is it just constant once you engage your loop? 

 

1.  Serial I think.  I have an email in to Atomic support to confirm.

2.  Seems to happen with all algorithms.  Tried it with a bunch of different factory presets.

3.  Feedback is constant.  I will try to record some samples and post them here.

[nickrose]

It looks as though the Amplifire has a series effects loop. You can confirm this by setting KillDry – this should then mute the signal in PRE mode.

 

My guess is that the problem is caused by one of two things:

1) The unit is not actually in PRE/POST mode, even though you think it is. Can you confirm that you see a PRE or POST  indication  as described on p.29 of the UM ?

2) You have some kind of cabling issue, where the FX loop signal is appearing at the normal input – probably weak grounds.

If it is neither of these it is hard to know what the problem is – my guess is that it is something at your end, as this is not a known issue.

[avalanchis]

nickrose wrote:

It looks as though the Amplifire has a series effects loop. You can confirm this by setting KillDry – this should then mute the signal in PRE mode.

 

My guess is that the problem is caused by one of two things:

1) The unit is not actually in PRE/POST mode, even though you think it is. Can you confirm that you see a PRE or POST  indication  as described on p.29 of the UM ?

2) You have some kind of cabling issue, where the FX loop signal is appearing at the normal input – probably weak grounds.

If it is neither of these it is hard to know what the problem is – my guess is that it is something at your end, as this is not a known issue.

KillDry does mute the signal in PRE mode, so it must be series.

1)  iPad says it is in PRE/POST mode.  (Pedal – General Settings – Routing)

Also, if I go into System mode it says PRE.PST  (System – Utils – Route)

2)  I’m using quality cables and have tried several different types of cables to try to rule out a cable issue.  The only thing plugged into Input 1 is a guitar cable which is about 8′ long with my guitar connected to the other end.  Have also tried several different guitars.

After some further experimentation I’ve found that it only happens with very high gain settings on my amp.

I dropped the loop send level by 6db and compensated by raising the loop return level to +6.0 db and the problem seems to go away.  

I think the default loop level on the Amplifire is too hot and causing crosstalk on Input 1.

 

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