I've been listening to my modified SB2 very carefully over the last few days, and it has been troubling me that it didn't sound as good as I remembered.
It seemed to me that there was something wrong at the HF end which was making it sound a little harsh and fatiguing - a characteristic that I was sure was not there before. So I ran some frequency sweeps through it (mainly to check that the response was flat), and I noticed a certain amplitude grantularity. This got me thinking that the new volume curve might be responsible (I've been using the SB2 direct to an amp with the SB2 volume control), and so I've been running some numbers through excel. I'm not sure exactly how the 'linear' volume control was implemented, but assuming a 2.5% reduction in amplitude per step, volumes of 40, 35, 30, 25, 20, 15 etc would still produce 'lossless' results with 16 bit (CD-derived) sources. If SD implemented the intermediate volumes using 1/256 rounded coefficients, all the remaining volumes would have been lossless too. However the new 'log' volume control uses 1.27dB reductions per step, which gives NO lossless volume settings - except for 40 (assuming 16 bit audio data). So is this what I and jhwilliams + girlfriend are hearing? Well I've reverted to a pre-volume-control-nightly, and I am convinced it sounds better. So Sean, I have a suggestion. The log volume control is clearly a better approach overall, but could you implement a version that uses 1/256 rounded multipliers for (say) volumes 20-40, and non-rounded multipliers below? No critical listening can really take place at -25dB+ with 'normal' amp gains /speaker efficiency, so the levels below 20 (which can't be smoothly rounded in 1/256ths) don't really matter. In the interests of bit-perfect audio and all that .... -- Patrick Dixon www.at-view.co.uk _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/lists/listinfo/audiophiles
