High pitch squeal when i plug my guitar into Vertex Effects Buffer interface in front of my HX STOMP

[p_ambrico96]

Hello guys,

 

I have a hybrid setup with an HX Stomp acting as the core of it. 

The signal flows in this way:

1. GTR ->Pedal Pawn Fuzz -> Crybaby->Vertex Effects Buffer Interface-> Hx stomp Input
2. I have some ODs in the LEFT effect loop
3. Right effect loop is used when I want to use a real amp with 4CM 
4. Left output goes to Amp return when using 4CM, L/R outputs go to FOH otherwise. 

 

I built the pedalboard to have the maximum flexibility in terms of routing.

 

Now, when using the Stomp  with amp sims I noticed a high pitched feedback/squeal (like a microphonic pickup type of squeal), the only fact is that I was playing with headphones so any microphonic pickup issue should be off the table, I also tried to switch guitars and to my surprise nothing changed. I went through the troubleshooting and I plugged the guitar directly intop the Stomp and I could go with the highest of the gains without problems, I also plugged into the PP Fuzz and the Wah bypassing the buffer interface and I came to the conclusion that the "problem" is the buffer interface. 

 

Do you have any explanation for that? That interface cost me a lot and I would not like to sell it or to put it off the board.

 

Thank you in advance for the answers.

[waymda]

This is a complete guess, but... the product description say it is

 

1) loading the guitar pickups properly with the same loading as your guitar would see if plugged into a tube amp and 2) converting the signal to low impedance, driving the line so it is the least susceptible to environmental factors that might alter the tone

 

Have you played with the input impedance setting of the Stomp, and does it make a difference? 

 

The Stomp Manual says the below - does that mean there's some form of double impedence loading going on, and your mention of microphonic feedback suggests too much high end being passed.

 

2 1 In-Z
HX Stomp has an impedance circuit on its Main L/R 
inputs that affects tone and feel by loading your guitar’s 
pickups as they would by an effect pedal or amplifier. 
A lower value will typically result in some high fre-
quency attenuation, lower gain, and an overall “softer” 
feel. A higher value provides full frequency response, 
higher gain, and an overall “tighter” feel. The “Auto” 
option allows the impedance to reflect the impedance 
of the first block in the signal path—also see the Auto 
Impedance option in “Global Settings > Preferences”

 

As in the first line this is just guessing as I am no electrical engineer.

[Schmalle]

Most likely caused by an ungrounded signal chain.

 

Try plugging into a grounded device. E.g. connect the HX's Out with an amp [that has a 3 contact mains plug] - you don't need to turn the amp on.

[p_ambrico96]

On 5/27/2024 at 6:51 AM, waymda said:

This is a complete guess, but... the product description say it is

 

1) loading the guitar pickups properly with the same loading as your guitar would see if plugged into a tube amp and 2) converting the signal to low impedance, driving the line so it is the least susceptible to environmental factors that might alter the tone

 

Have you played with the input impedance setting of the Stomp, and does it make a difference? 

 

The Stomp Manual says the below - does that mean there's some form of double impedence loading going on, and your mention of microphonic feedback suggests too much high end being passed.

 

2 1 In-Z
HX Stomp has an impedance circuit on its Main L/R 
inputs that affects tone and feel by loading your guitar’s 
pickups as they would by an effect pedal or amplifier. 
A lower value will typically result in some high fre-
quency attenuation, lower gain, and an overall “softer” 
feel. A higher value provides full frequency response, 
higher gain, and an overall “tighter” feel. The “Auto” 
option allows the impedance to reflect the impedance 
of the first block in the signal path—also see the Auto 
Impedance option in “Global Settings > Preferences”

 

As in the first line this is just guessing as I am no electrical engineer.

 Thank you very much for the answer.

Yes I tried with every value of the input impedance parameter on the stomp and nothing changed. I usually set it to 1 MOhm. The fact is that the buffer interface should have the send input/output passive (not buffered) and the squeal is still there. I can't wrap my head around this. I need to check cable by cable I guess.

 

Maybe there is a problem with the power supply(?) (also this is a guess).

[p_ambrico96]

On 5/27/2024 at 9:50 AM, Schmalle said:

Most likely caused by an ungrounded signal chain.

 

Try plugging into a grounded device. E.g. connect the HX's Out with an amp [that has a 3 contact mains plug] - you don't need to turn the amp on.

 

I'll try that, or I can l just unplug the output to see if this makes a difference, since I was playing with the headphones. I can tell you that I had the same problem by going to a mixer with both outputs.

 

Thank you very much.

[p_ambrico96]

Maybe I got the answer to get rid of it!

 

Not sure what's the cause, however. I unplugged the outs from the stomp (I was with the headphones) and the feedback was gone, then I went to plug the left output to the return plug of the interface and it came up again. I moved a couple of cables and even in my home PA no feedback whatsoever. I'm emailing diretcly Vertex Effect to understand better what's happening here.

 

Thank you very much for your answers guys!