Latency Question

The B2M™ Universal Bass to MIDI Converter.

Latency Question

Postby bassistclem » Sat Sep 13, 2014 6:25 pm

I have just started testing my new B2M and have had mixed success. After getting over the miracle that it works pretty much as I would have hoped I set about seeing how usable the thing could really be.

All the sugested tips on playing accuracy and optimizing tone worked fine and the only thing in question is the device latency.

I am plugging the midi out directly into a Roland JV1080 and the latency is definately a problem. I recorded the sound from the 1080 alongside the bass direct signal and measured the note latency to 50ms on average. Is this the normal or is my device maybe not fully functional? Having seen some players demonstrate the B2M on Youtube (Lee Slkar inparticular) I feel sure they couldn't have played in the manner they did with this kind of latency.

I have tested the 1080 with a keyboard and it is spot on. I have also tried a few basses and playing techniques and although this gives different results regarding note accuracy, the latency is only 50ms at best.

Any feedback on this would be greatly appreciated.
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Re: Latency Question

Postby james » Sun Sep 14, 2014 7:30 pm

Have you tried playing the higher notes on the bass to check the latency? I suggest to try this first, because it will give the lowest latency conversion and let you hear what's going on. Also, look at the MIDI LED on the B2M because this will light at the same time MIDI messages are sent. See if you can notice any latency between the MIDI LED flashing and hearing the note.

There's nothing in the B2M that could go wrong that would affect latency. If there are problems, it's usually because a lower string is vibrating at the same time as a higher note, and the B2M has to wait a little longer to resolve the note.
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Re: Latency Question

Postby bassistclem » Mon Sep 15, 2014 12:17 am

Yes, the latency definately improves when playing higher. The latencey I am getting at E3 is about 18ms and from there up the device definately becomes more usable. That though is not always going to be practical, depending on how it's intended to be used. If that is the case then I'm not sure why Sonuus didn't just sugest bassists buying the guitar version and specify use over a certain pitch?

I have since found the latency spec on the manual and says that a E1 should be 32ms, definately lower than I have managed after trying many basses, techniques and EQ settings. I haven't tried a pure sine wave yet ;)

I will persist for a while and see if I can improve on the results I have managed so far, but hope that the 32ms is achievable as promised down at E1....

I'll post the results and findings as I go and hope to help the product as I am relatively impressed, just feel as if falls down at the last hurdle somewhat :?
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Re: Latency Question

Postby james » Mon Sep 15, 2014 9:53 am

Please do keep us updated.

The optimal latency, e.g., 32ms at E1, requires a nice cleanly-plucked string; a good transient. The most important thing the B2M wants is to be able to easily identify the start of the plucked note. So you want an obvious change in level when note starts. This lets the B2M reset its algorithm to align with the note start. If this doesn't happen, the B2M's processing may not be optimally aligned with the note start and this can add extra latency.

You get similar problems with a bowed violin. Though the note frequencies are higher, the gradual onset of the note means there is no transient to detect, so latency can suffer.
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