If it quacks like a duck ....

[JohnW63]

What causes it and what can be done about it ?

The reason I ask, is that after another Ovation thread, where one common complaint was the quacky sound of the 30+ year old UST pickups, I started experimenting with my Ovation and various amps. What I found is what you plug one into has a lot to do with how much quack you get.

Peavey Back Stage Chorus = a good amount of sharp tones and easy to make "quack".

Randall Commander II = No quack, even if played hard.

UltraSound 15 = easy to get feedback, but not much quack, unless I play near the bridge.


So, if there are folks who know the science of pickups can comment on what it is, and why some combinations can make more duck sound than others, that would be an enlightened topic. I'm not afraid of electronics theory, I took enough in college. Let's hear some ideas.

[Tico]

No quack here ... not even a trace of duck poo.

I use a DPA d:vote VO-4099G when I gig or record with my Martin D-28 Authentic 37 VTS.
I didn't even have to drill a single hole into my guitar since it just clips on externally.
No batteries, though being a true condenser, it requires 48 volt phantom power.

It's a ultra-high-end tiny shotgun super-cardioid mic.
It mounts on the outside of your guitar.

I LOVE this mic.
It is astonishingly transparent & accurate.
It sounds exactly like your instrument, no coloration.
DPA offers the exact same VO-4099 mic for many instruments from piano, to sax, to violins, to drums.
You only need different mounting gizmos for various instruments.
Also, I love that I can instantly control the EQ at the source by changing where it is pointing and adjusting the angle with respect to the sound hole.

FF to 5:00 past using two 4099s on piano to get to using one on an acoustic guitar.
https://www.youtube.com/watch?v=YhXXp3q2Io4

Way not cheap: $620

Did I say I LOVE this mic! ... not just for live performance, but also for recording!
I struggle to hear any difference between it and and my AKG-414 XLS mic pair, which are each twice the price.

http://www.sweetwater.com/store/detail/VO4099G

[Picker2]

'Quack' is the result of what they call a nonlinear response of the pickup. Basically this means that when the string vibrates twice as hard, the output signal of the pickup increases more than twice. Doesn't seem like a big deal, but since this nonlinearity is also frequency dependent, it means that the tone of the amplified signal will be dependent on how hard you drive the pickup.

The same happens in tube guitar amplifiers by the way, but we have come to like that. For a pure acoustic string, most people don't appreciat the artificial 'quack' that nonlinearity creates.

Effectively, the piezoelectric pickup acts like a microphone with an equaliser attached to it, and the sliders of the equalizer move up and down depending on how hard you got the strings. This makes it very hard, if not impossible, to correct piezo quack with tone control.

However, tone filtering does help a bit and some amplifiers have built in anti-quack filters. These amps make piezo guitars sound better, however if you plug in a non-piezo guitar with magnetic pickups, it typically produced a dull and muffled sound.

[fazool]

Great explanation Picker2.

Piezo quack is probably my greatest guitar pet peeve and one of those sounds that grate on me like dragging fingernails on a chalkboard (while chewing tinfoil). I hate, hate, HATE piezo quack.

I've been to a *lot* of concerts. The worst sound I've ever heard was an acoustic show by my favorite artist because it was all piezo quack - it was so very bad. And he was playing a very well-known piezo guitar.

I just don't understand how anyone can't cringe when they hear it.

I think a SBT piezo is less offensive than a UST piezo and I love a good mic-ed acoustic or a good magpu, but quack is the scourge of the guitar world, to me.

[Bill Yellow]

I had an older 1869 that quacked so bad I thought I had snares on it instead of strings. My newer C2079LX does not, at least under my hand. So I guess they fixed something.

[Steve DeRosa]

Since Picker covered the theory I'll do the nuts-and-bolts, what-works-on-the-job part...

Charlie Kaman developed the piezo-based system for the Ovation line in the mid-60's - well before the advent of dedicated acoustic-electric amplification - with the goal of reproducing a reasonably "acoustic" tone through the comparatively-primitive equipment of the day; that said, when it's used within its original design parameters it's fairly successful. I've been using a Custom Balladeer with first-generation electronics (volume-only) for the last 34 years and the trick is to run it through a relatively "lo-fi" system, i.e., one that has a natural rolloff above 5kHz or so; simply put, 8" (or smaller) speakers and piezo/horn tweeters - de rigeur for a modern acoustic amp - are a no-no; fifty years ago "big-gig amplification" meant a blackface Twin Reverb (or Ampeg B-12XT if you were from the NYC Tri-State area), miked up if necessary, and IME plugging into the low-gain input of a comparable rig (mid/high-power 1x12"/2x12"/1x15" analog amp - I used a Peavey Bandit 65 for years) will still give the best results - BTW I've got a Randall RB-120 combo myself and I'm not surprised...

FWIW if you're interested in doing a live-gig comparison, listen to Neil Diamond's 1972 Hot August Night and Simon & Garfunkel's The Concert in Central Park, recorded ten years later; Neil's using the older miked-amp setup I described above - sounds like an Ovation, only louder - while Paul is DI'd through a "modern" full-range PA system, and the quack is so bad that I probably would've strangled the sound man had I been there...

[SpruceTop]

ALERT!!!

Before this turns into another Ovation-bashing thread, for those not in the know: QUACK is a general characteristic of most Under Saddle Transducers (UST) and is NOT limited to the UST pickups in Ovation guitars!

[SpruceTop]

I recently had a 2008 Ovation Adamas 2080 NWT with the high-output OCP-1 UST pickup assembly feeding into the onboard VIP-5 Preamp. The VIP-5 Preamp features five Fishman Aura Images that can be blended into the mix. This guitar had excellent acoustic and an amplified tone without any quack when an Aura Image was mixed-in. The Ovation OCP-1 pickup assembly senses both string and top vibration and IMHO is still a very viable pickup for acoustic-guitar amplification.

[fazool]

Originally Posted by fazool

... it was all piezo quack - it was so very bad. And he was playing a very well-known piezo guitar....

Originally Posted by SpruceTop

Before this turns into another Ovation-bashing thread...QUACK is a general characteristic of most Under Saddle Transducers (UST) and is NOT limited to the UST pickups in Ovation guitars!

I wasn't speaking of Ovation at all.

[Mandobart]

Originally Posted by SpruceTop

ALERT!!!

Before this turns into another Ovation-bashing thread, for those not in the know: QUACK is a general characteristic of most Under Saddle Transducers (UST) and is NOT limited to the UST pickups in Ovation guitars!

Correct. All piezoelectric elements work by producing a variable millivolt output in response to the application of strain. All under saddle transducers are constantly under strain from the downward pressure applied by the string tension through the saddle. They are never in a zero strain state (unless the strings are completely slack). So they are already biased toward saturation, the point at which the maximum output is achieved and any further strain simply overdrives it.

Under soundboard piezos, OTOH, are free to respond to soundboard vibration and are in a zero strain state when not being played. They have a wider dynamic range and are not pre-biased to overdrive. You can get them to quack, usually if the input impedance of your amp/PA doesn't match the output impedance of the piezo (usually 1 to 10 megohm).

[SpruceTop]

Originally Posted by fazool

I wasn't speaking of Ovation at all.

I know you weren't and I wasn't aiming my post at you or anyone in particular. I just wanted to inform folks, who aren't aware of UST tonal characteristics, that quack is a general characteristic of UST transducers and is not limited to Ovation's designs. It seems every thread that mentions Ovation guitars eventually features posts that bash the company and its products and I wanted to try to focus the discussion on UST pickups and the preamps they feed.

[fazool]

Originally Posted by SpruceTop

I know you weren't and I wasn't aiming my post at you or anyone in particular. I just wanted to inform folks, who aren't aware of UST tonal characteristics, that quack is a general characteristic of UST transducers and is not limited to Ovation's designs. It seems every thread that mentions Ovation guitars eventually features posts that bash the company and its products and I wanted to try to focus the discussion on UST pickups and the preamps they feed.

Gotcha.

Personally, I admire Ovation guitars.

[martingitdave]

You can try a $99 TC Helicon Body Res pedal. See if it does the trick for you.

[Mandobart]

Originally Posted by fazool

Gotcha.

Personally, I admire Ovation guitars.

Me too. I still have my '82 12 string that I bought back then. It has a great tone. I added a twin under soundboard JJB PPS200 a few years back. Sounds great plugged in. My first guitar, a late 70's Applause was the first instrument I ever bought so I've kept it for sentimental reasons.