Sure. I am aware that dangers exist of lifting grounds, as generally not recommended. For devices that have safety approval ratings, as CSA here in Canada, it is expected that in the passing of those standards sufficient safeguards exist to protect against electrical shock hazards, etc. Having a physical switch as part of the device suggests that adequate safeguards exist. The amplifiers do have a safety approval sticker, though I am uncertain if that sticker is one recognized by CSA as a necessary condition of approval here in Canada.
The 1 pF coupling comes from the triple shielding construction of the transformer. its real when measured the way they do it. However if the cord in and the cord out are anywhere near each other the HF noise will go right around the transformer. Yes they are noisy, and heavy. I have on in storage as well.
Good morning. Regarding yesterday's listening session it turned out that Andrea's three traveling companions were interested in listening too. Previously when I talked to Andrea by email he wasn't sure if the other folks would want to stay or go do something else while Andera listened. As a result there were some different opinions expressed, mostly about the main two dacs, DAC_Lite and Custom AK4499. As it turned out we only listened to one piece of music on vinyl. For that same piece of music we also listened to DAC_Lite with and without its optional buffer board. Also, as it turned out we never got around to listening to the Topping. (IMHO D90 would have been rated the worst sounding dac of the three, although possibly the best measuring one).
Since I was already familiar with the sound of all the dacs and the phono, already had opinions about their various strengths and weaknesses. However, I wanted to hear the opinions of our guests before giving my own opinion. Therefore I just played whatever music Andrea asked to for. It was basically some tracks he likes to use for listening evaluations.
The first piece of music was Mary Black performing 'Columbus.' It features female vocals, piano, violin, stand up bass, and a little hand percussion. I think there was general agreement that DAC_Lite sounded better without the optional buffer. After Mary Black, the rest of the session compared only unbuffered DAC_Lite and Custom AK4499. Don't recall exactly what we listened to next except I believe it was all classical. Last musical selection was an example of an high-res classical recording with a lot of dynamics, 'Bozza: Children's Overture.'
Although I couldn't understand all the comments between the ladies regarding the dacs because of the language differences, they provided some, I think accurate, comments about the sound of the two dacs. The other gentleman visitor commented in terms of perceived frequency response (such as the characteristic strong midrange sound common to some non-oversampling dacs, as opposed to the thinner midrange presentation of oversampling dacs such as Custom AK4499). (My comment: Although that difference seems to be perceived as frequency response, I'm not sure is that's exactly what is. Tried to correct that thin sound in ADCs and DACs before using EQ, which didn't exactly seem to be the inverse function. Mids could made louder but still sounded a bit thin. Haven't tried EQ with Custom AK4499 however). One of the ladies described Custom AK4499 soundstage starting more forward and perhaps extending more the back, as compared to DAC_Lite. Overall the ladies seem think both dacs sounded very good, even if there were differences. After the hi-res piece was played Andrea remarked that both dacs sounded almost the same with it, which I think I know what he meant but not sure if everyone else agreed on that. Probably most people were more inclined to take more note of the differences as opposed to the similarities. One thing I did notice is that I don't recall hearing any criticism of DAC_Lite from the group, and particularly of what I thought to be its most noticeable imperfection (at least as it is implemented here), which is that for a well recorded CD, high frequency articulation was a bit unfocused and dry (where 'dry' means so not much of recorded room reverb coming through in that frequency range). When I mentioned it, Andrea seemed to understand what I was getting at. Think its something he may keep in mind for some future dac project.
After we were finished listening Andrea and I talked briefly about trying DAC_Lite with a shunt regulator for Vref. See if it can help HF articulation and or other aspects of the sound. Also, Andrea mentioned to me that he had never heard an oversampling dac like mine. I took that to mean he never heard one that was more or less in the same SQ class as a good multibit Nyquist dac. I also told the group that I thought Custom AK4499 could be made to sound a little better. Although I don't really consider its sound quite fully optimized, AK4499 is now obsolete so I will probably try to make some future dac sound a little better instead of working much more on this one.
Since I was already familiar with the sound of all the dacs and the phono, already had opinions about their various strengths and weaknesses. However, I wanted to hear the opinions of our guests before giving my own opinion. Therefore I just played whatever music Andrea asked to for. It was basically some tracks he likes to use for listening evaluations.
The first piece of music was Mary Black performing 'Columbus.' It features female vocals, piano, violin, stand up bass, and a little hand percussion. I think there was general agreement that DAC_Lite sounded better without the optional buffer. After Mary Black, the rest of the session compared only unbuffered DAC_Lite and Custom AK4499. Don't recall exactly what we listened to next except I believe it was all classical. Last musical selection was an example of an high-res classical recording with a lot of dynamics, 'Bozza: Children's Overture.'
Although I couldn't understand all the comments between the ladies regarding the dacs because of the language differences, they provided some, I think accurate, comments about the sound of the two dacs. The other gentleman visitor commented in terms of perceived frequency response (such as the characteristic strong midrange sound common to some non-oversampling dacs, as opposed to the thinner midrange presentation of oversampling dacs such as Custom AK4499). (My comment: Although that difference seems to be perceived as frequency response, I'm not sure is that's exactly what is. Tried to correct that thin sound in ADCs and DACs before using EQ, which didn't exactly seem to be the inverse function. Mids could made louder but still sounded a bit thin. Haven't tried EQ with Custom AK4499 however). One of the ladies described Custom AK4499 soundstage starting more forward and perhaps extending more the back, as compared to DAC_Lite. Overall the ladies seem think both dacs sounded very good, even if there were differences. After the hi-res piece was played Andrea remarked that both dacs sounded almost the same with it, which I think I know what he meant but not sure if everyone else agreed on that. Probably most people were more inclined to take more note of the differences as opposed to the similarities. One thing I did notice is that I don't recall hearing any criticism of DAC_Lite from the group, and particularly of what I thought to be its most noticeable imperfection (at least as it is implemented here), which is that for a well recorded CD, high frequency articulation was a bit unfocused and dry (where 'dry' means so not much of recorded room reverb coming through in that frequency range). When I mentioned it, Andrea seemed to understand what I was getting at. Think its something he may keep in mind for some future dac project.
After we were finished listening Andrea and I talked briefly about trying DAC_Lite with a shunt regulator for Vref. See if it can help HF articulation and or other aspects of the sound. Also, Andrea mentioned to me that he had never heard an oversampling dac like mine. I took that to mean he never heard one that was more or less in the same SQ class as a good multibit Nyquist dac. I also told the group that I thought Custom AK4499 could be made to sound a little better. Although I don't really consider its sound quite fully optimized, AK4499 is now obsolete so I will probably try to make some future dac sound a little better instead of working much more on this one.
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Thanks, for that report, Mark. I'm wondering whether the DAC_Lite set-up featured correction for the SIN(X)/X based treble-droop caused by NOS? If not, perhaps, that was responsible for the above subjective upper frequency observation?
So, a social meeting where most of the participants where keen to retain relations during the rest of the trip. It means that the whole gig is absolutely worthless except for perhaps the ones that was there at the time. I know this situation all to well - 2 or more instances which all has some sort of "investment" (don't think monetary here necessarily) but wants to stay polite - as the party breaks up, everyone thinks "ok, mina was best... the psychology around this is pancake batter thick.... and its also a moving target re: references and preferences so nothing can be deduced from it - and as described above, by anyone really... so you see mk4, there is no idea to try to write about sound impressions - but we all knew that, didn't we...
But by all means, please share more/other vacation experiences. Pictures is always fun to see ;-)
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But by all means, please share more/other vacation experiences. Pictures is always fun to see ;-)
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The Custom AK4499 dac does automatic hardware conversion of PCM to DSD256. The AK4499 chip is configured to run in DSD Volume Bypass mode. That's the way it sounds best to me, so that's how it works.
Interesting. The only time I have heard DSD is some years ago (in whatever configuration I can't remember) was very impressive.
Much previous listening experience, both in PCM and DSD modes. I described its sound in another thread some time ago, and perhaps earlier in this thread.
Please don't get me wrong, its a great value at its price point. The other two dacs we auditioned could never offer the same value proposition as D90. However, this wasn't about value. It was about perceived SQ.
Regarding the other music I used prior to this listening session, it included a wide variety of music including Beethoven, opera, pop, rock, jazz, etc.
D
Deleted member 537459
I guess it was a nice day!
did you compare it with which V-Ref on the dac lite? source?
thank you
It is all subjective (listening preferences) and individual. I wonder what is the outcome from such listening sessions. Again, just momentary subjective preferences. And a kind of prejudice. Individual prejudice based on topologies and price. No controlled DBT to confirm the results.
IIRC I wrote earlier in the forum, maybe in this thread, that I first tried a dual LT1083 regulator for Vref. Later I built a secondary NGF regulator that basically looked a lot like a darlington cap multiplier with a current source powered LED voltage reference. Regulators were on their own separate dedicated transformer windings so that dual positive regulators could be used to produce + and - regulators with matched characteristics. Liked the sound of that better than the dual LT1083 regulators alone. Therefore the secondary regulators were used for the listening session.
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Deleted member 537459
Forgot to mention tried the regulators with some resistive shunts in parallel with the dac load. Ended up using Dale CMF 250R in parallel with 100R. Seemed to be a sweet spot with that loading.
That's the key phrase, right there. IOW, it may have been all in your head. Thanks for addressing that.
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