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Volume with left-right balance, volume display and remote control
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I don't know if the I2C pins in buffalo are 5V tolerant, but if you are using a 5V Arduino, then you need to use a voltage level converter.
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I2C pins should never be driven high by a micro controller (I2C master). It's actually part of the spec. :) They should only be high impedance(input) or low (or open drain). The target device pull ups should dictate the high voltage state. If the Arduino does not follow this spec, that's a pretty huge and dangerous oversight. In any case those pins are 5V tolerant according to ESS, but I have never felt the need to test that. but don't use any I2C controller that drives lines high. That's just plain wrong. :) Edited by user Sunday, February 28, 2010 5:59:20 PM(UTC)
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Russ, I'm not familiar with the spec and don't know in detail how Arduino operates, but last I checked, the pull ups in the Arduino I2C pins are enabled when the I2C functions are enabled. And the Arduino is a 5V device. My I2C LCD is a 5V device, but OPUS is a 3.3 (and non 5V tolerant) device and are both in the same bus. Thus I have a level converter between the Arduino and OPUS. It has been working reliably for almost a year.
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It is usually perfectly OK for weak pull ups(very high impedance) to be enabled so long as the SDA/SCL pins are not actively being driven high(low impedance). Weak pull ups on most micro controllers are usually something in the 20-47K range. Cheers! Russ Edited by user Sunday, February 28, 2010 9:13:11 PM(UTC)
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Everything is pretty much ready, inlcuding the Arduino firmware, display, IR support, wiring and case work. I have never made a hole in 10mm thick aluminium. Only thing missing is the output resistors are missing since i haven't received them yet. Thank you for your help. About the output resistors. I'll prolly go for 1Vrms Balanced output to add 12db more headroom in the digital domain. Here is how the hardware looks like:  Edited by user Thursday, March 4, 2010 10:14:01 AM(UTC)
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Excellent job. :)
You could do like I did and make the volume go from 0 to 11. :)
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The problem is that my amp has quite high gain, and at 4Vrms the suitable volume was around -48...-38db depending on the music and if its night time. The dac has about 127db of analog dynamics, so that would mean around 21 bits of effective resolution in the digital domain. Right? So basically what i need to do is optimize the volume control for 16bit of audio data and 5 bits of volume control. That means that suitable volume should be found somewhere at -30db or higher. This is pretty much what i get with 0.5Vrms output from B32s (using 287ohm 0.1% metal film resistors), but its right there at -30db. The B32s manual states that one should not go lower than 287ohm for the output limits for optimal performance. Is this already somewhere in the limit, so what i am gaining in the digital domain is taken away by the worse analog domain? Or does 0.5Vrms still give the same performance in dynamics with 16bit audio as 4Vrms? Should i find a way to lower the gain of my amp instead or am i good like this? Edited by user Sunday, March 14, 2010 7:57:54 AM(UTC)
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Hi elviz, since I wrote that I have done some more experimenting, and I am quite confident you will get good results even if you go down to say 100R.
I also think you meant 187R in you post above. :)
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Russ White wrote:Hi elviz, since I wrote that I have done some more experimenting, and I am quite confident you will get good results even if you go down to say 100R.
I also think you meant 187R in you post above. :) I don't know what should be there, but it states 287R for 0.5Vrms in B32s' manual. And also "Values >= 287R are suggested for lowest distortion". Does that mean that the actual limit at the time of writing the manual was meant to be 187R which is now lowered down to 100R? But anyways, that is good news. Thanks again! Edited by user Sunday, March 14, 2010 9:48:31 PM(UTC)
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Yes the 287R was likely a typo. :)
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What about the other resistor values in the Buffalo32 manual, no other typos correct?
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Rank: Administration
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Twisted Pear Audio Support
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Volume with left-right balance, volume display and remote control
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