Double Bass Tuner pedal pops with DB only?

[bigthemat]

Hey friends,

Not sure if this is the right spot, but, since this only happens with the DB figured I'd start here.

So I'm new to DB and still working out the kinks on my pedalboard for when I'm doubling or need to use the pickups. At my last gig I noticed there was a loud pop when I engage the tuner. This doesn't happen with my electric, so I assume it has to do with the piezo pickup. The tuner pedal is a Korg Pitch Black which works fine on both electric and DB, and I like having the mute option. Currently using a Fishman BP-100, which, is fine, but I don't know if a new pickup would fix this issue (and yes, I want to get a better pickup but need to justify getting more gigs before getting one).

Is there a reason why the piezo would make the pop? Should there be a buffer or different signal chain? My current path is bass > tuner > hx stomp > amp.

TIA

 

[Wasnex]

Not sure exactly what is going on, but my guess it's related to this: A piezo appears as a capacitor, which is an electronic device that can hold a charge.

Because of the capacitive nature of piezos, they form a high-pass filter when connected to a low impedance. The ideal impedance can vary on the design/size of the piezo element, but minimum acceptable load is generally 1M or more. The function of a buffer connected to a piezo pickup is to provide a high impedance so that the cutoff of the resulting HPF is below the audible range. If the switching noise you are experiencing is due to the piezo, a buffer is likely to help.

I believe your tuner has true bypass switching, which can be noisy. The noise is one of the reasons why buffered bypass can be superior. Essentially what happens with true bypass is a charge builds up on the open contacts, and when you close the switch the charge jumps across the contacts and causes a pop. Perhaps connecting a capacitor across the input of the switch would allow a larger charge to form, which would make the pop louder. The tuner itself may have a small internal leak that feeds this build up of charge.

There are various design strategies to overcome this, such as placing a high value resistor across the open contacts to prevent the build up of a charge. Here's an article for background: What really causes switch pop

 

[bigthemat]

Not sure exactly what is going on, but my guess it's related to this: A piezo appears as a capacitor, which is an electronic device that can hold a charge.

Because of the capacitive nature of piezos, they form a high-pass filter when connected to a low impedance. The ideal impedance can vary on the design/size of the piezo element, but minimum acceptable load is generally 1M or more. The function of a buffer connected to a piezo pickup is to provide a high impedance so that the cutoff of the resulting HPF is below the audible range. If the switching noise you are experiencing is due to the piezo, a buffer is likely to help.

I believe your tuner has true bypass switching, which can be noisy. The noise is one of the reasons why buffered bypass can be superior. Essentially what happens with true bypass is a charge builds up on the open contacts, and when you close the switch the charge jumps across the contacts and causes a pop. Perhaps connecting a capacitor across the input of the switch would allow a larger charge to form, which would make the pop louder. The tuner itself may have a small internal leak that feeds this build up of charge.

There are various design strategies to overcome this, such as placing a high value resistor across the open contacts to prevent the build up of a charge. Here's an article for background: What really causes switch pop

so sounds like I need a buffer, or a new tuner. I see the polytune 3 has a built in buffer, maybe that's the easiest option (the korg is also a pain to see in the sunlight...)

 

[Wasnex]

so sounds like I need a buffer, or a new tuner. I see the polytune 3 has a built in buffer, maybe that's the easiest option (the korg is also a pain to see in the sunlight...)

I would try running the tuner later in the signal path first.

The manual for the HX stomp seems to indicate that the input impedance can be adjusted, but I didn't see the values.

 

[bigthemat]

I would try running the tuner later in the signal path first.

The manual for the HX stomp seems to indicate that the input impedance can be adjusted, but I didn't see the values.

that's probably the easiest and cheapest option haha. When I use the built in tuner on the stomp it doesn't pop, but, I don't love the tuner and I don't have an available footswitch to turn it on/off.

 

[Ryan in PDX]

I've been using the pitchblack tuner for many years. It's true bypass. Putting it after the buffer solved this problem.

 

[lowfreqgeek]

You typically can't use a true bypass mute on a piezo without getting the pop when you switch. I don't know what impedance the BP-100 likes, but the Strobostomp Mini has a 5Meg buffered input Z. I've played around with it on my DB and it most certainly does buffer the Realist and the switching is silent. However, I'm coming (back) to the conclusion that my Realist works best with 1 to 2Meg. At 5Meg+, it just takes more HPF and low-end sculpting to get the bottom right. The BP-100 may very well prefer the 5Meg, though.

 

[lowfreqgeek]

Is there a reason why the piezo would make the pop?

I meant to address this in my previous post, but the reason it pops is that a piezo is essentially modeled like a capacitor, which holds a charge if there's no resistive path to bleed off the charge. When using a true bypass switch, the piezo is allowed to float during switching. It doesn't take long to build up that charge, so as soon as it's connected back to the signal path, there's a small DC potential difference between the piezo and the input circuit (which is at 0VDC) that has to discharge through the input circuit.

Hopefully that makes sense.

 

[Sam Reese]

FWIW, the Fishman BP-100 has never caused a pop in my world. I've owned one for 30+ years (recently got it back from a "young gun") and this pop isn't anything I've ever encountered with it, back then or very recently.

 

[Sam Reese]

so sounds like I need a buffer, or a new tuner

I use a Peterson Strobostomp HD tuner. They say, " 100% Pop-less True Bypass -We've redesigned and greatly improved the way incoming signal was handled in true-bypass mode to deliver a perfectly silent experience when muting your signal.
A dual relay circuit effectively bleeds out any incoming signal before powering the tuner down resulting in a silent transition without affecting tone quality."

I've never thought much about it, but maybe this could help. If you have a friend with the tuner, borrow it and check it out(?). Or go buy one at your local "big box" and return it if you don't like it...