VAX 700 Acoustic - high pitched "data" background noise

Started by Smash, November 07, 2017, 04:13:22 AM

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Smash

Something that really only becomes noticable when I notch up the treble to get some extra top end but I can hear a digital high pitched noise in the background - compressor obviously drags it up.

I'm running through iTrack dock into ipad. Weirdly it's more noticable on some models than others.

if it helps, using lower alternate tunings reduces the frequency of the data noise so I guess this means it's coming in pre-pitch shifting.

Bizarely seems to be worse since changing from GHS White Bronze to DR zebras (which I have discovered I really don't like). Need magnetically active strings for FTP.

I've tried moving around the room, keeping distance from ipad and phone but it appears constant

Anyone had anything similar?

Elantric

#1


https://www.soundonsound.com/reviews/line-6-variax-acoustic-700
Sure -On my VAX 700 Acoustic I also hear the noise artifacts you mention when I run the guitar into an average preamp ( iTrack Dock) and apply high compression with an ipad app

( Live I tend to use VAX 700 Acoustic straight into a passive DI box or LR Baggs Venue Active DI

Even an old XT Live works adequately well as a floor FX module for VAX 700 Acoustic as that allows a suitably clean digital domain signal path ( AES/EBU digital connection using VDI cable) DSP to DSP and skip an extra D/A > A/D conversion

Its not a perfect world

And a VAX 700 Acoustic is never going have the high dynamic range of an acoustic guitar with a pure analog signal chain ( Sunrise acoustic pickup, HighLander PU > Grace Felix Preamp 
http://highlanderpickups.com/catalog/catindex.htm

http://www.gracedesign.com/products/felix/felix.htm

Smash

I hear you - do you think the noise us internal from Vax or do you think it's picking up the noise from iTrack somehow (proximity doesn't seem to make a difference - noise down cable shield maybe?)

rolandvg99

#3
QuoteI hear you - do you think the noise us internal from Vax or do you think it's picking up the noise from iTrack somehow (proximity doesn't seem to make a difference - noise down cable shield maybe?)

Sounds like a possible iTrack PSU issue.

To V or not to V: That is the question.

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Elantric

#4


There is residual clock noise from the internal  VAX 700 Acoustic DSP circuitry, and the average D/A converters that ends up in the onboard  analog output stage 

adding more external gain and external compression all contribute to raising  this noise floor into the audible realm


QuoteSounds like a possible iTrack PSU issue.

Its true - you can achieve lower noise if you use external battery power  and no AC Mains
https://www.vguitarforums.com/smf/index.php?topic=10662.0

Smash

OK thanks - I'm running VAX exclusively on battery now after a rocky start with batteries it now seems quite stable and certainly a lot less noise than with phantom mains power, it's just that last bit!

I'll run direct to mixer without and iTrack to compare noise floor and go from there.

Thanks for replies.

EDIT - the digital noise DOESN'T increase if I use the VAX on board compressor - but external compressor drags it up (as exoected) - weird. Yet I can hear the noise change during model selection then go back to constant which suggest it is the VAX generating it. More testing!

Incidentally having a good response to GHS White Bronze - qwuite bright but the VAx is a little dark so good match and plenty of mag output for the FTP - almost too much lol!