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How to connect acoustic guitar with built-in piezo pickup and preamp to TonePort UX2
by Pykon on 2009-11-21 13:11:55.5030


I experience a problematic performance of my piezo-acoustic guitar with built-in active preamp/eq when trcording through instrument input on my TonePort UX2. The sound is thin, full of harmonics and subtle resonances, and I can hear more of a staccato than a melodic string sound. I/ve tried everything: changing the preamp's battery, checking out cables, changing strings, picks etc - all of them with no effect. Yesterday by chance I came up with an idea to plug the guitar into line input at the back of my UX2 and the guitar finally started to perform as it should! The difference is huge.

And here comes a question: how should such a guitar be connected to UX2? Should I use front Instrument normal input, or stick to back Line input?

And maybe the Instrument Input is corrupted and makes also my electric guitar and bass sound unnatural? Is there any way to check it out in terms of sound quality (No, I don't have any other guitar interface to compare with)?

More info:

- I record through Gearbox with ALL the amps/mics/cabinets/effects off

- I keep levels securely under peaks, no possibility of distortion

- Recording is done with the same software and settings in both cases (instrument normal/line in)

- I/ve also checked my piezo-acoustic guitar through Instrument pad input, as it has lower sensitivity. The sound was slightly better than the one recorded through normal instrument input but worse than line input option

the pickup/preamp/eq built into my acoustic guitar is signed by Shadow, should work well at least.

So, to put it another way:

- how should I connect acoustic guitar with piezo pick-up and active preamp to UX2;

- how can I know if the UX2 Instrument input doesn't lower also the quality of my electric guitar and bass sound?

Thx in advance for help,


RE: How to connect acoustic guitar with built-in piezo pickup and preamp to TonePort UX2
by ricksox on 2009-11-24 11:34:58.0160


It's possible that the output signal from your guitar is just too hot for the either instrument on the TonePort to handle. This makes sense considering the Line inputs work better as they are designed to receive a Line Level (+4db) input signal.

If plugging your guitar into the Line Inputs work for you then you should keep using those inputs.

Have oyu plugged any other straight magnetic pick up guitars into the front Instrument inputs of the TonePort? If so, how did they sound?


Re: RE: How to connect acoustic guitar with built-in piezo pickup and preamp to TonePort UX2
by Pykon on 2009-11-24 13:24:06.8540

Hello again,

here are the results of my modest diagnostics:

- the signal from pre-amped piezo-acoustic guitar (guitar's preamp volume to the max) tops at some -10 dB when connected into UX2 Line input (value from Gearbox's input meter);

- the same guitar with similar preamp settings tops at some -7 dB (I aproximate this value from UX2 VU's as it's not shown directly in gearbox - when Instrument input is selected, input VU meter disappears) when connected through UX2's Instrument input;

- during the test I used "as dry as possible" setting in gearbox (no amp, no cabinet, no effects, volume at 75 %;

- despite the fact it is pre-amped, guitar's signal doesn't seem do overdrive the Instrument input circuit, as input meters show some headroom even with guitar preamp's volume to the max;

- I've just made similar comparison with my electric guitar (2 x humbucker) and it topped at some -16 dB (line input) and -10 dB (Instrument input) both with no effect/cabinet/amp gearbox settings;

You can hear three attached tracks with my piezo-acoustic guitar. One recorded through Line input (guitar preamp vol to the max), second plugged into Instrument input (guit. pre vol to the max) and, to add some chili, there is also the third track containing sound recorded through instrument input but this time with guitar's preamp volume reduced to 70 %. In theory, it should sound OK, as reducing volume at input lowers the risk of unwanted peak distortion. But that's not the case - the sound is slightly better, but can't compare to the one captured with the line input.

By the way, the difference between sound "from" instrument and line input is not purely distorted/clean type, it's something more complex and hard to describe - instrument input appears to have some kind of a superfast limiter/echo at high frequencies when co-operating with my piezo-acoustic guitar. Is it possible that there are some “hidden” peaks that UX2 peak indicators don’t show? And how to be sure there are no such peaks as in the Gearbox there’s no input meter in Instrument mode?

What's surprising is a modest sensitivity difference between these inputs even with a humbucker pickup. Is it correct?

Please, listen to attached files and compare the sound.

I'll try to do some tests with electric guitar/bass sound, I've never tried to plug them in line input, but maybe it's time to check this out?

PS. I've spent tons of hours on every mix eq-ing and cleaning up acoustic guitar tracks from unwanted harmonics, resonances etc. Now I know I'll have to play and record all the stuff again, this time with line in input. But what if I'm to do the same job on bass and electric guitar tracks...

Even given my enthusiasm for making music - a hard task.




RE: How to connect acoustic guitar with built-in piezo pickup and preamp to TonePort UX2
by ricksox on 2009-11-25 15:11:45.5780


The only difference in the inputs that I am aware of is with being able to accept instrument vs. line level signals.

I'll have a listen to your clips to get an idea of what you are hearing. I'm on holiday until Monday so I'll get back to you on this when I return. Thanks for your patience.


RE: How to connect acoustic guitar with built-in piezo pickup and preamp to TonePort UX2
by AParedes on 2009-11-25 15:19:04.3790


Normally a guitar should be connected to the instrument input, but the built-in preamp may be pushing the output beyond what the instrument input can handle. In this case you will want to use the Line in.

General recording pricipals say that you should get the hottest signal you can (without clipping), so depending on how you set up you input these three tracks could be greatly affected in gain strucure alone. impedance and output level can also change 'tone", so you need to keep this in mind when working on tracks. The input meters in your recording SW may give you a better idea of what is happening, but the bottom line is "how it sounds".

You may want to try a different sound card to see if you get the same results.

You can also see the following link for more information:

Please let us know if you need further assistance, or close out the ticket as “answered” if your situation has been resolved.

Re: RE: How to connect acoustic guitar with built-in piezo pickup and preamp to TonePort UX2
by Pykon on 2009-11-26 01:17:56.9800


so you suggest it's correct that the UX2's instrument input pollutes signal from piezo-acoustic guitar so significantly that it can be easily heard despite -10 dB recording headroom? If so, what can I call a "safe" recording level for instrument input?

Maybe I should sent my TonePort to service point for some tests, but I'm not sure that such testing procedures covering dynamics exist.

In the meantime I'll record evetything with line in input, even electric guitar and bass, as I can't feel safe about sound quality when using instrument input.

It's not as it's supposed to be I guess...

Musician needs something predictable in his recording gear to rely on.

Wondering if this time UX2 cuts the warmth ot the guitar or not - could you have any pleasure when playing guitar with this question in mind?



RE: How to connect acoustic guitar with built-in piezo pickup and preamp to TonePort UX2
by AParedes on 2009-11-30 15:07:57.0150

As we have already stated, normally an "instrument" level device should go into the "instrument" input, but the built-in preamp may be pushing the acoustic output beyond what the instrument input of the UX2 can handle. It is really up to the end user to decide what "sounds best" as far as recording levels, warmth, and headroom/noise floor.

The information above may not be current, and you should direct questions to the current forum or review the manual.