Help indentifying weird noise on my AT-200 and Piezo luthier kit + graphtechs.

Started by cags12, March 20, 2017, 04:47:03 PM

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cags12

Hi All,

I am very aware from so many sources that piezo pickups are problematic in high gain scenarios and when palm muting. However, I am not sure if the issue I am experiencing is one of those well known piezo problems or a general problem with the auto-tune/alt tuning features. I have adapted my palm muting technique but what I am experiencing is something I do not have clue how to avoid.

Would someone be able to help me by listening to my audio clip and telling me if that is expected and if on magnetic hex pickups that does not happen?

Basically on the audio clip I have very high gain patch (noise gate off so everything can be heard). Initially I am palm muting on Standard E, notice that nothing sounds awfully wrong (well there may something there but not very noticeable). But as soon as I tune down to Drop C in this case (or any other tuning), the decay section of the palm mute strum experiences a very noticeable nasty kind of distortion/static/scratch. Please bear in mind I am not directly touching the piezos but only the strings very close to the saddles.

On the final section of the clip I am not even palm muting but simply touching the strings with my finger. Ohh, I almost forgot if I gently hit the guitar or back of the neck, the distortion also happens.

Does anything of this happens on the magnetic pickups? you will have to crack your metal amps up :)

Audio clip:
https://www.dropbox.com/s/4kdb2u8zms52tu9/distorted_static_noise.wav?dl=0

cags12

After a lot of troubleshooting with the guitar and extensive reading about pitch shifting algorithms and specifically the one that Antares uses. I have concluded that the distortion is generated by the algorithm changing pitch used by Antares when cross-talk occurs.
Unlike other algorithms like vocoders or FFT which can cope with polyphonic waves (multiple notes), Antares's algorithm is very susceptible to polyphony introducing distortion artifacts when sound from neighboring string invade another channel of sound. Antares's algorithm is far superior only when a monophonic (1 note) is processed, like Vocals or perfectly isolated strings.

Quoting Antares admin guide

"The most important consideration with pickups is potential distortion created by the algorithm changing pitch. What happens with hex pickups is that some sound from neighboring strings gets into each string's data. The cross-­‐channel sounds have different periods than the primary sound of the channel, and dropping or repeating cycles to change pitch creates discontinuities in the cross-­‐channel sounds. This results in distortion."

My guitar, even though is piezo equipped, is very cross-talk proof except by one aspect that I will explain below.

When palm muting, independently of the technique employed and saddle isolation, string vibrations are transferred through the palm to neighboring strings causing the piezos to pickup cross-talk and ultimately distortion by the pitch shift algorithm. Strange though, if I palm mute at the nut, the distortion does not occur even though I managed to prov (by disconnecting saddles) vibrations are also transferred through my fingers/palm to neighboring strings. This would suggest that the closer to the pickup, the worse.

My question now to anyone who reads this and owns a luthier kit with Magnetic Hex pickup, even GK users which also use mag Hex is:

Does this type of pickup present the same issue (cross-talk through the hand) when palm muting + Alt tuning + high gain? Please I would appreciate your help



Elantric

if you are using the AT-200B breakout box . A lot of this noise is from the 8 pin cable


if you seek Rock / Metal / Blues tones from any DSP Modeler,  Piezos are a major battle, and why I avoid them ( i prefer good tone)

Big part why ANY Variax or Peavey AT-200,  does not work for me for Rock / Metal / Blues tones

and IMHO none of these DSP Guitar Modeling systems deliver "perfect tone"  -

If I'm getting paid I need to deliver acceptable results. I'll use these systems for the "acoustic guitar intro, or acoustic break - mid song - while the normal Mag PUs with the pitch of the genuine strings deliver 90% of my tone all night.   







QuoteMy guitar, even though is piezo equipped, is very cross-talk proof except by one aspect that I will explain below.


(cross-talk through the hand) when palm muting + Alt tuning + high gain?

https://www.vguitarforums.com/smf/index.php?topic=16061.msg128023#msg128023

Same experience here with my Peavey AT-200  - I had to rebuild it to make it work - and the Black Oxide Chrome does you zero favors for  EMI / Ground Noise control ( I paid $300 for a used AT-200, and it was about $200 more than it was worth 

I'm setting up a gently used AT-200

first issue I experience is Hum, and  after the guitar is intonated properly  - i now have a few dead piezo saddles too, from lack of enough downward pressure on a few bridge piezo saddle. To fix this I'll add a small shim in the neck pocket to slightly raise the bridge saddles and contribute more downward force on the piezo saddles.

To tackle the hum, its important to inspect the String Ground to the Bridge

An electrical ohm meter revealed there was no proper string ground

I lifted the Bridge to have a look and found an unconnected Ground Earth wire under the "Black Chrome" Bridge plate

There is a common assumption that "Black plated"  metal parts on guitars look cool, but in electrical terms this black plating can create problems for proper earthing and EMI/RF emmissions.
http://www.finishing.com/287/47.shtml
simple test for anyone with a  'black plated metal Bridge - measure the DC resistance between the bridge and the the Ground Sleeve connection on the 1/4" Guitar Output jack. This should  be a solid "0.0" ohms when a proper string earthing ground connection is preset

My AT-200 was no connection   = huge hum, lots of noise anytime I palm mute  ( what fool designed this?)

There is a problem with most Black Plating used today, its "Hi-Z"  (i.e. it does not conduct well !)  In fact using a Ohm meter and measure the DC resistance from one corner to the other corner on the same Black Plated Bridge on the continuity setting of my Fluke meter yields a "No Connection" reading  - the Black plating must be removed and bare steel exposed to make electrical connection with the earth wire which gets sandwiched under the steel bridge plate when installed correctly



GuitarBuilder

Quote from: Elantric on March 24, 2017, 04:29:27 PM
if you seek Rock / Metal / Blues tones from any DSP Modeler,  Piezos are a major battle, and why I avoid them ( i prefer good tone)

Amen!

QuoteBut hey - when I play in my surf band we dont need,  nor have much use for any of these systems ;)

Unless you start a new Heavy Metal Surf band!  ;D

QuoteSame experience here with my Peavey AT-200  - I had to rebuild it to make it work - and the Black Oxide Chrome does you zero favors for  EMI / Ground Noise control ( I paid $300 for a used AT-200, and it was about $200 more than it was worth

I can't agree more - my AT-200 purchase was 100% waste of money.  The basic guitar is not good enough even after an upgrade.  That is why I decided to put the ATG luthier kit into a scratch-built body instead; the result is 1000x better than the AT-200 (which is for sale, BTW).
"There's no-one left alive, it must be a draw"  Peter Gabriel 1973

cags12

Quote from: Elantric on March 24, 2017, 04:29:27 PM
Same experience here with my Peavey AT-200  - I had to rebuild it to make it work - and the Black Oxide Chrome does you zero favors for  EMI / Ground Noise control ( I paid $300 for a used AT-200, and it was about $200 more than it was worth 
Quote from: GuitarBuilder on March 25, 2017, 08:42:47 AM
That is why I decided to put the ATG luthier kit into a scratch-built body instead; the result is 1000x better than the AT-200 (which is for sale, BTW).

Thank you for your answers and advices. Yes I am pretty aware of the limitations of the AT-200. However you have not precisely answered exactly my question. I know you both have a luthier kit with the magnetic Hex. What I really want to know is if the magnetic Hex pickup is also susceptible to cross-talk caused by vibrations transferred through the palm?

I really need to know this because I also have a luthier kit but the piezo version (special order) I plan to install on a custom guitar. I'd get another kit (magnetic version) only if this issue is not present on it. Could you please advise and/or even replicate if you do not mind? The distortion you are able to hear in the audio clip can also be heard in clean patches if you put attention.

Thank you


Elantric

QuoteWhat I really want to know is if the magnetic Hex pickup is also susceptible to cross-talk caused by vibrations transferred through the palm?

With a Mag hex PU I get zero palm mute noise or anomalies 

With a Piezo hex PU I ALWAYS get palm mute noise anomalies 

QuoteI really need to know this because I also have a luthier kit but the piezo version (special order) I plan to install on a custom guitar.

Since you already have prior bad experience with piezo hex PU's on the Peavey AT-200, seems a poor choice to repeat that mistake.   

cags12

Quote from: Elantric on March 25, 2017, 04:27:38 PM
With a Mag hex PU I get zero palm mute noise or anomalies 

With a Piezo hex PU I ALWAYS get palm mute noise anomalies 

Since you already have prior bad experience with piezo hex PU's on the Peavey AT-200, seems a poor choice to repeat that mistake.

To be honest, I never noticed this issue until I got the luthier kit and started tweaking my high gain patches to work along the new Graphtech saddles and the new DSP4 board and complete pack. When I realized about it, I reverted back to the AT-200 stock configuration and the issue was also there.

Precisely the intention of this thread was to avoid any future mistake.

After self-educating me on pitch shifting algorithms and methods, I kinda felt hopeless when using Antares's algorithm even if I chose the Mag Hex PU. Antare's is for sure the best pith shifting software but only when processing monophonic sounds. Introduce cross-talk (polyphony), and everything changes.

But if you say you do not have the same issue, hopes have been restored.