Originally Posted by evdberg
We have come a long way from our initial (jumped to) conclusion: that there might be a bug in the G68 firmware. This conclusion was based on the report that the raise in quality was not gradually with the raise in level, but only worked on exactly +3dB.

With George's new 0.5dB difference test it became clear the effect might be gradually after all. This also means that you might indeed say that digital volume control comes at a cost (which George suggested earlier).

Your above post explores that further to explain where the cost factor lies: with the DAC. It got me thinking, and maybe the following might explain it a bit more. Most current DAC's are the delta/sigma type: this is a sort cross between 1-bit and multi-bit. Mostly they are around 4 to 6 bits and use oversampling to compensate for the lack of resolution (like SACD uses 64 times oversampling for its 1 bit scheme). So if you lower your volume with 1 bit (6dB), you actually reduce the resolution of the DAC to only 3 to 5 bits. It is clear that the effect of digital volume can heavily depend on the DAC used in the system. For instance there may also be a big difference between Mk1 DSP speakers (5K, 5K5 and 6K) and Mk2 and current DSP speakers. Did anybody try the +3dB mod with Mk1 DSP speakers? It's just a thought.

Quote from Wiki "I don't think it gradually gets better as you approach +3.0dB. But I could be wrong on that." I always try to cover my a$$ then I followed it up with a test to confirm it.

I've thought of a dozen more tests I could do fully understand things. The rears one I just did was one of them. While my wife was out on a walk smile

But I'm confident +3dB is ideal whether it was gradual or a step. But I could be wrong on that too.

Your right that it looks less like a bug. But more like a design weakness (IMHO) in not taking full advantage of the DSP Speaker DAC. And it would be very easy to fix (or should I say improve the implementation, and to be honest I'm amazed they didn't).

Don't some Delta sigma's also come in 1-Bit? I'll have to have my local EE genius explain DAC's again to me smile

I'm glad your reading my posts in detail and understand the implications of the "progress" and I think we are in complete agreement.

- Fiddler (IMHO)

If you think listening to music is fun, try learning an instrument.
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