[SlimDevices: Audiophiles] Re: SB2: reduce analog out voltage by 10x?
Deaf Cat Wrote: > ""eleven"" - FAB! Have you noticed how the player volume in the web interface goes up to 11? That's not a mistake. :-) -- cbemoore ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
[SlimDevices: Audiophiles] Re: SB2: reduce analog out voltage by 10x?
Hi Sean, Just downloaded the latest firmware, and it works perfectly. Thanks! (BTW, I've set the SB2 preamp control to 30dB attenuation, *and* my power amp to 10dB attenuation, and the volume is just about perfect! I must have a very loud amp!!!) Chris -- cbemoore ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
[SlimDevices: Audiophiles] Re: SB2: reduce analog out voltage by 10x?
Does this change for volume control degrade the quality of the stream? I saw a prior thread on analog volume reductions dropping bits. This sounds like it is changing voltage instead so I have no idea of whether it's changing the data or is truely like a preamp volume control. Thanks for any insight into this. -- rme ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
[SlimDevices: Audiophiles] Re: SB2: reduce analog out voltage by 10x?
Cheers for the explanations, All Clear, except, hope you don't mind another (maybe daft) question: >Not quite. dB (decibels) are a logrithmic measurement, usually referenced to some standard value. dBu are referenced to 0.7746v. >For the stock SB2, output is 2.12v(rms). In dBu, this is: >20 x log10(2.12 / 0.7746) = 8.75dBu >Say you want to reduce your output to 0dBu, you need to add 8.75dBu of attenuation. This would reduce the max Vout(rms) to 0.7746v. So, take 8.75dBu off of 2.12V to end up with 0.7746V (Which is what my power amp would like-roughly 0.8V-cool) So, if we add 8.75dBu attenuation (it would be safest to round it to 9dBu I suppose) into the Option Box in the Audio settings for the SB2 we should be fine. But how does the 8.75dBu relate to the 0.0 - 63.0dB scale? Oh Boy! Takes alot of brain power to almost understand that taking off is addin on and 0 is 0.7, quite intresting how logs relate though. >I hope the above helps. Absolutly! >BTW, the firmware has just been relased. I've downloaded it and can report that it's working well. Is this in the 6.2, 2005-09-09 download? >I'm not sure that the way of setting the attenutation is the most intuitive of user interfaces, but it does the job. Your telling me!! Who would have thought it a! Buy a bit of audio equipment and then starting to want to know about Logarithms!! Thanks again for the explanations. > How about just a pop-up list with "quiet", "not so quiet", "loud", "eleven"? :) ""eleven"" - FAB. -- Deaf Cat ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
[SlimDevices: Audiophiles] Re: SB2: reduce analog out voltage by 10x?
JJZolx Wrote: > > If the DAC offers 128 discrete steps of volume control, have you > considered the possibility (maybe as an option) of reversing the roles > of the software volume control and the DAC's digital volume control so > that we'd have the option of controlling volume in the digital domain? Eh? They're both digital - just one's done in the CPU and one's done in the DAC. -- seanadams ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
[SlimDevices: Audiophiles] Re: SB2: reduce analog out voltage by 10x?
seanadams Wrote: > I just put something simple in there to make it work... open to better > ideas. > > Dean, Vidur and I have been talking about volume control in general - > there's a lot more to it than meets the eye, once you consider > crossfading, replaygain, headphone use, amp use, etc. Right now the > sofware volume control uses an 8-bit linear value which by itself > doesn't give enough levels on the low end of the scale. With this > additional "preamp" control (7 bits of half decibels, done in the DAC) > it should solve the problem for those who've been stuck on the low end > of the bar with not enough resolution. But yes, the UI is a bit > abstruse. How about just a pop-up list with "quiet", "not so quiet", > "loud", "eleven"? :) If you want to make use of all 128 steps in the digital control then a more intuitive interface might be to simply enter an integer from 1 to 128 (maximum) (or perhaps 0 to 127) and explain that at the maximum setting the signal is unaltered and that each step below the max gives 0.5db of attenuation. If the DAC offers 128 discrete steps of volume control, have you considered the possibility (maybe as an option) of reversing the roles of the software volume control and the DAC's digital volume control so that we'd have the option of controlling volume in the digital domain? -- JJZolx Jim ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
[SlimDevices: Audiophiles] Re: SB2: reduce analog out voltage by 10x?
Robin Bowes Wrote: > > I'm not sure that the way of setting the attenutation is the most > intuitive of user interfaces, but it does the job. > I just put something simple in there to make it work... open to better ideas. Dean, Vidur and I have been talking about volume control in general - there's a lot more to it than meets the eye, once you consider crossfading, replaygain, headphone use, amp use, etc. Right now the sofware volume control uses an 8-bit linear value which by itself doesn't give enough levels on the low end of the scale. With this additional "preamp" control (7 bits of half decibels, done in the DAC) it should solve the problem for those who've been stuck on the low end of the bar with not enough resolution. But yes, the UI is a bit abstruse. How about just a pop-up list with "quiet", "not so quiet", "loud", "eleven"? :) -- seanadams ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
[SlimDevices: Audiophiles] Re: SB2: reduce analog out voltage by 10x?
Deaf Cat said the following on 09/09/2005 19:06: Em, I do feel a little daft joining in this conversation about attenutation and dB and 0dBu's as I have not got the faintest idea what you rather technical people are all talking about, but would like to learn a little if possible... Good attitude! The Preamp Volume Control is default Zero, which means full volume. approx. 2Vrms? - (normal CD o/p) The std SB2 output is 6v(peak to peak) which is 3v(peak) or 2.12v(rms). "Normal" CD output tends to be 0.775v(rms). I guess attenuation has something to do with adjusting the signal level which in this case equates to the volume. Correct. Attenuation means reducing the level. The range 0.0 to 63.0 - So the setting 0.0 being approx. 2Vrms and 63db being 0V, if I had a power amp that likes 0.8V, a setting closer to the 63.0 than the 0.0, would please the power amp...? Not quite. dB (decibels) are a logrithmic measurement, usually referenced to some standard value. dBu are referenced to 0.7746v. For the stock SB2, output is 2.12v(rms). In dBu, this is: 20 x log10(2.12 / 0.7746) = 8.75dBu Say you want to reduce your output to 0dBu, you need to add 8.75dBu of attenuation. This would reduce the max Vout(rms) to 0.7746v. So, the firmware lets SB2 know what these settings mean, or does the firmware help with SNR? The firmware is the bit that implements this functionality by controlling the DAC chip in the SB2. If you do understand how I am thinking, and what I would like to understand in the simplest form, I would love to hear nice simplistic explanations if possible, thanks for your patience. I hope the above helps. BTW, the firmware has just been relased. I've downloaded it and can report that it's working well. I'm not sure that the way of setting the attenutation is the most intuitive of user interfaces, but it does the job. R. -- http://robinbowes.com If a man speaks in a forest, and his wife's not there, is he still wrong? ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
[SlimDevices: Audiophiles] Re: SB2: reduce analog out voltage by 10x?
Em, I do feel a little daft joining in this conversation about attenutation and dB and 0dBu's as I have not got the faintest idea what you rather technical people are all talking about, but would like to learn a little if possible... The Preamp Volume Control is default Zero, which means full volume. approx. 2Vrms? - (normal CD o/p) I guess attenuation has something to do with adjusting the signal level which in this case equates to the volume. The range 0.0 to 63.0 - So the setting 0.0 being approx. 2Vrms and 63db being 0V, if I had a power amp that likes 0.8V, a setting closer to the 63.0 than the 0.0, would please the power amp...? So, the firmware lets SB2 know what these settings mean, or does the firmware help with SNR? If you do understand how I am thinking, and what I would like to understand in the simplest form, I would love to hear nice simplistic explanations if possible, thanks for your patience. -- Deaf Cat ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
[SlimDevices: Audiophiles] Re: SB2: reduce analog out voltage by 10x?
seanadams wrote: OK I added this. The setting goes from 0 to 63 db of attenuation in 0.5db steps. Firmware will be updated soon - need to sync up with Vidur on that first. Just to add... I reckon 2.5dB of attenutation will bring the level down to 0dBu. R. -- http://robinbowes.com If a man speaks in a forest, and his wife's not there, is he still wrong? ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
[SlimDevices: Audiophiles] Re: digital output format?
I would be astonished if any 16-bit DAC has a problem with the other 8 bits being populated. BTW here's a good explanation of s/pdif - better reading than the IEC spec. http://www.epanorama.net/documents/audio/spdif.html -- seanadams ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
[SlimDevices: Audiophiles] Re: digital output format?
hi sean thanks for clarifying - I wrote to the author of the DAC design and will have to wait for his answer for finding out what really happens there. so to summarize SB2 sends the following format (certainly a bit more complex in real life): MSB 0x00 - 0x0F 16 bit data LSB 0x10 - 0x17 8 bit additional data (all bits 0 if source is only 16bit and volume is 100%) now I think that the mere *sending* of the 8 zero LSB bits might trouble my DAC - which is only a presumption up to now. the thing is that the used DA chip is so low-end that it only accepts 44.1khz 16bit data, and that the receiver on the DAC might happily decode the 24bit data and sends it as-is (meaning with the 8 zeroed bits) over to the DA chip, which in turn refuses to decode _anything_. otherwise I have to tell I am very happy with the SB2! regards nicola -- Nicola Fankhauser ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
[SlimDevices: Audiophiles] Re: SB2: reduce analog out voltage by 10x?
seanadams Wrote: > OK I added this. The setting goes from 0 to 63 db of attenuation in > 0.5db steps. Firmware will be updated soon - need to sync up with Vidur > on that first. Wow - didn't expect it to be *that* quick! Thanks Sean!! -- cbemoore ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
