i2m on acoustics

The i2M musicport™ MIDI Converter & Hi-Z USB Audio Interface

i2m on acoustics

Postby braguesa » Fri Jun 08, 2012 2:28 am

Testing my i2m for about 2 weeks with some acoustics (Classical guitar, folk guitar, mandolin, ukulele and flute), my conclusion is midi tracking is not good on this device.
Yes, I did read other posts, I can do a clean playing on that instruments and they have very good pickups installed, including flute!
The best result I got was with a mandocaster that has magnetic pickups (like electric guitar). I've a Korg pandora mini that doest a much better audio tracking for octaves and synth effects. When I tryed midi recording, I was shocked with the bad results, worse that live playing!
Is there something I'm missing?
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Re: i2m on acoustics

Postby james » Fri Jun 08, 2012 8:56 am

Can you describe what is happening in detail? It's hard to suggest things other than what's in the standard FAQs without specific information.

Audio tracking for synth effects and octaves really isn't comparable to MIDI tracking. MIDI isn't forgiving of any glitches, whereas for an effect these can be "glossed" over without you noticing. The real comparison would be for the Korg pandora mini outputtint MIDI, but of course it can't do that.
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Re: i2m on acoustics

Postby braguesa » Fri Jun 08, 2012 11:48 am

When I play a note, I can feel the tracking delay of the i2m. First, I thought it could be from my system, but when tried with a normal usb midi cable on my keyboard, everything was perfect!
Results are far from fast tracking on the i2m, the only way I can use it is with slow tunes. Whe can notice that on every youtube video, there is always a delay tracking if you pay attention on right hand picking. It works good like a piezo preamp, thought. Audio is very good.
I saw an ipad software demo that can do the midi tracking like the i2m and seemed somehow like the same, but cheaper...
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Re: i2m on acoustics

Postby braguesa » Fri Jun 08, 2012 12:07 pm

I can post an audio demo, if necessary...
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Re: i2m on acoustics

Postby james » Fri Jun 08, 2012 1:00 pm

The tracking on the i2M should be very fast. Of course, there is some latency because there has to be to perform the required pitch-detection, but on a guitar it should be around 17ms (on the lowest notes) and much lower on the higher notes. This is comparable to using an electric guitar with an amp around 5 meters away (because of the time it takes sound to travel that distance). You can usually adapt to delays like this very easily.

On the higher notes, where tracking is fastest, we've yet to meet someone who can play faster than the i2M can track.

If you are experiencing very slow tracking, there must be something not quite right causing it. It sounds like your system is working because you checked with a MIDI keyboard. You can also do a similar test using the i2M's "Latency Test Mode" accessed from the i2M Editor. This flashes the logo on the i2M in time with MIDI notes so you can get a visual indication of the latency of your system, including the i2M, but not including pitch-detection.

An audio demo (of both the original instrument sound, and the resulting MIID) would be very useful to let us work out what's happening.
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Re: i2m on acoustics

Postby braguesa » Fri Jun 08, 2012 1:17 pm

Latency test mode works perfectly, the problem seems like pitch detection. Later I'll post some audio demos of my problems.
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Re: i2m on acoustics

Postby braguesa » Fri Jun 08, 2012 4:04 pm

Here, some audio tests:
http://soundcloud.com/amagalhaes/sets/i2m-test/s-HHebY
The first scale on the mandolin is dry
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Re: i2m on acoustics

Postby james » Fri Jun 08, 2012 4:35 pm

I've had a quick look and have some questions:

On the "Flute" sample, the first part, is this an acoustic flute triggering MIDI? That part looks very good, with very low latency. The only time the latency increases is when the flute fades in slowly (the signal has to get above a threshold before it will be recognised).

On the mandolin, are you playing both of the unison strings? That won't work for MIDI conversion because you are playing two pitches at the same time but the i2M is assuming there is only one pitch it has to find. When this happens, the i2M will often lengthen the latency if possible to try and capture more information to work out what's happening. But even so, I wouldn't expect good results when two strings are playing at once.
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Re: i2m on acoustics

Postby braguesa » Fri Jun 08, 2012 5:11 pm

the flute is an alto recorder with a piezo pickup.
Ok, mandolin has double strings, but they're in tune. Well, I think I'll have to live with that and adapt my live usage of it. It is a good preamp, indeed...
Regards
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Re: i2m on acoustics

Postby braguesa » Sat Jun 09, 2012 12:04 am

And what means, "Exclusive" on preamp gain settings?
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