Never knew what Piezo quack was... HELP!

talonted · #1 07-20-2011, 12:28 AM

Short and sweet... Breedlove J350ef, jumbo guitar, been gigging it for 2 years, perfect guitar for me. LR baggs stage pro with preamp. Sounded fantastic until I got a setup to drop action a bit for more lead playing. Guitar sounds fine now, but when I dig in I get this horrible "quack" on the initial attack of each strum. Any ideas on why or how to fix?

Garthman · #2 07-20-2011, 02:47 AM

Quote:

Originally Posted by talonted

Short and sweet... Breedlove J350ef, jumbo guitar, been gigging it for 2 years, perfect guitar for me. LR baggs stage pro with preamp. Sounded fantastic until I got a setup to drop action a bit for more lead playing. Guitar sounds fine now, but when I dig in I get this horrible "quack" on the initial attack of each strum. Any ideas on why or how to fix?

A properly done set up should not have increased piezo "quack". It sounds to me as if you have a poor contact problem. It could be that the technician has not ensured that the saddle base is flat and/or the UST is not seated correctly. A couple of choices: take it back and have him sort it or, if that is not possible, use some self-hardening (also called "Mexican") clay to re-seat the UST and saddle.

The latter is a great and easy trick to solve poor pick-up contact. Roll out a thin (~1mm) layer of the clay (available from most art and craft shops) and cut a couple of thin strips that will fit into the saddle slot. Put one strip in the base of the slot and fit the UST, put the other strip on top of the UST and fit the saddle and press it down firmly. Restring and tune up to tension and leave overnight for the clay to harden.

It is worth doing this on any guitar fitted with a UST - it mellows the "quack" even on a well set-up guitar. The clay is easily removed should you ever want to reverse the process.

talonted · #3 07-20-2011, 03:14 AM

GREAT answer! Due to the fact that I'll have to have my guitar re-setup afterwards for the action being raised, I think I'm gonna take it back to the guy and have him check it out and suggest the hint to him. The guitar tech is one hell of one, and my guitar plays like a DREAM now... Just gotta get over this little issue.

elroyjetsn · #4 08-01-2014, 05:14 PM

I put a little piece of wax paper in the pocket to line it and help prevent the saddle from gripping the sides and absorbing the vibrations and chafing (quacking).

A bone saddle helps too, they are greasy, slips more freely than plastic.

akafloyd · #5 08-01-2014, 06:08 PM

Are you certain it's piezo quack and not a little fret buzz??

jonfields45 · #6 08-02-2014, 07:12 AM

Lower action, less downward pressure on the saddle, no string-to-string balance issues (which eliminates a not flat saddle bottom), and I would wager the saddle is binding in the slot. I've run into this once before, degraded the plugged in tone as you describe, and lightly sanding the saddle to every so slightly reduce its width solved it for me. Jon

dberkowitz · #7 08-02-2014, 05:46 PM

Pull 7k down about 3-6db with enough Q to soften the bite.

elroyjetsn · #8 08-12-2014, 05:16 AM

Someone told me to set the volume on my preamp at half to get more natural sound. If your piezo pickup has high output it may be saturating the preamp at full volume setting.

DukeBerryman · #9 08-25-2014, 09:40 PM

Quote:

Originally Posted by elroyjetsn

Someone told me to set the volume on my preamp at half to get more natural sound. If your piezo pickup has high output it may be saturating the preamp at full volume setting.

My preamp is so powerful, it can really compress the sound. I turn down everything on the preamp to 50% and then don't touch it. I change the volume using the volume knob on my amp.

This may not help you on stage when you want to easily change volume but preamps can really over do it. You really have to think of the preamp Volume as more like an amp Drive control.

rschultz · #10 08-26-2014, 09:57 AM

Quote:

Originally Posted by Garthman

A properly done set up should not have increased piezo "quack". It sounds to me as if you have a poor contact problem. It could be that the technician has not ensured that the saddle base is flat and/or the UST is not seated correctly. A couple of choices: take it back and have him sort it or, if that is not possible, use some self-hardening (also called "Mexican") clay to re-seat the UST and saddle.

The latter is a great and easy trick to solve poor pick-up contact. Roll out a thin (~1mm) layer of the clay (available from most art and craft shops) and cut a couple of thin strips that will fit into the saddle slot. Put one strip in the base of the slot and fit the UST, put the other strip on top of the UST and fit the saddle and press it down firmly. Restring and tune up to tension and leave overnight for the clay to harden.

It is worth doing this on any guitar fitted with a UST - it mellows the "quack" even on a well set-up guitar. The clay is easily removed should you ever want to reverse the process.

So is the UST moving up and down in the slot... what causes the QUACK? I never knew that. Someone confirm this...

elroyjetsn · #11 08-27-2014, 03:05 AM

Quote:

Originally Posted by rschultz

So is the UST moving up and down in the slot... what causes the QUACK? I never knew that. Someone confirm this...

The piezo sensor generates electricity whenever it is stressed. In this case it has the saddle and the bottom of the slot pressing against it. On one side it senses movement(vibrations) of the strings thru the saddle(s) and the other side the vibrations going to and from the wooden slot and the top of the guitar.

Based on this, my guess is that the "quack" is the result of the saddle binding in the slot thus unable to transmit a fundamental cleanly during stronger string vibration which improves as the string vibration weakens, giving a "wah" like effect during each note that becomes more pronounced as the player strums, or plucks harder.

The effect is similar to the "blown speaker" where the speaker voice coil contacts the magnet assembly and it may sound OK at low volumes, but gets thinner sounding and raspy as you turn it up. In this case the saddle movement is restricted by the slot to an even greater degree.

jseth · #12 08-27-2014, 12:29 PM

Sounds to me like your action was lowered, so it's a bit more comfortable to play, but probably not as loud (I know you are amplified, but bear with me), so you are compensating by hitting the strings harder than you had been previously...

UST "quack" is absolutely related to how hard/firm your attack strength is; I played through a Fishman Matrix UST for over a decade and did not have an issue with the tone, not in the slightest... gigged with it a lot, always received compliments on how both my 6 and 12 string guitars sounded... and I have a light to medium attack.

I've had friends "sit in" and play a bit, and frequently notice that quack when their attacks are harder than mine...

This is all based on the assumption that the Element is installed correctly and all the electronics are working right, as well... sometimes, just replacing the battery can fix a whole lot of sonic disturbances...

joeguam · #13 08-27-2014, 02:04 PM

Does anyone know of a YouTube video or sound clip demonstrating the quack?

JRay · #14 08-28-2014, 03:10 AM

I think it's been noted before somewhere here, but this clip pretty much demonstrated piezo quack in all its fiery glory!!

https://www.youtube.com/watch?v=MIivG9llCwE

Ray

elroyjetsn · #15 08-29-2014, 08:45 AM

I noticed someone commented that the guitar sounds like it has "rubber strings". The quack just kills the tone instead of preserving the sweet bell quality of a good acoustic.

I've noticed that since setting the saddle with wax paper my Tak requires some severely agressive playing to get the quack. Next I may try using teflon tape to wrap the saddle and enable it to vibrate more freely.