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manisandher

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  1. Ah, missed that. Will take a look at it. Thanks. Mani.
  2. Chris, my understanding is that the DV2 is MQA-compatible. It'd be great to get Ed's views on MQA, and why he's decided to include it in the DV2. Is it just to give owners choice, or is it because he feels it has sonic merits? Mani.
  3. Great! I'll go ahead and order an ADI-2 Pro FS. (The M2 seems pretty good for the price though.) Mani.
  4. Thanks Paul, that's really, really helpful. I might hang on to my new M2 after all . I've got a Fireface 800, so will do some loopbacks (once I've fixed its SMPS - second one to fail on me on an FF800!). The ADI-2 Pro FS is supposed to be the king of modern 'affordable pro' ADCs. Any idea why it performs so badly in the loopback? Mani.
  5. Paul, as you know, I've been exploring getting hold of an ADC that would be up to the job of measuring the bit-identical differences I'm hearing. Here are the loopback measurements (most taken from the Gearslutz DA_AD thread) of the ADCs I currently have to hand: (* Potential future purchase.) I suspect that in the majority of cases it's the ADC that's the limiting factor in these measurements, and not the DAC. So, it seems to me that none of these are really be up to the job at hand... and the RME is considered one of the best currently available! So where to now? Mani.
  6. Thanks for your thoughts Peter. At this point, just a "nice discussion". No, I'm not going to get myself into any corner(s). At this point, I just want to gather some ideas and get a sense of how we could improve on the previous listening test. That's all. I'm absolutely not committing to anything. And I certainly wouldn't be listening to sine waves! That discussion with Paul was purely about testing the capability of an ADC, using a loop-back, and comparing against the source. We'd be looking for a difference of below -90dB or so between the resulting DA/AD and the source file. I just wanted to know what source would be best for the loop-back test. No listening involved whatsoever. OK, this gets to the crux of things. And it's why I think it's helpful to separate the methodology into two: 1) Proving that bit-identical replay can sound audibly different. ("Statistically") Can be done via a controlled blind ABX, and showing that A and B remain bit-identical. This was exactly what we did in the previous ABX. I'm confident that I could at least match my previous result in a new ABX, using streaming vs. local replay, say. But this shouldn't really be that controversial. As Paul stated earlier, jitter on the interface can cause timing errors. So, bit-identical replay certainly can sound different if something changes the amount of jitter reaching the DAC chip(s). I remember buying my first CD green marker pen, which certainly changed the sound... but unfortunately for the worst. I tried on on a couple of of CDs before cleaning their sides again and throwing the pen away. The green marker changed the sound, without changing any bits whatsoever. People seem to think that modern USB DACs are immune to these sorts of influences. I don't think so - based on my experience. 2) Understanding the mechanisms that cause bit-identical replay to sound audibly different. ("Technically") The biggest issue here by far is actual measurement. I totally agree that before any repeat ABX, we need to get a means of measuring the analogue output of the DAC that changes consistently with bit-identical changes upstream, e.g. streaming vs. local playback. You say it's impossible. I'd like to at least explore things further... Peter, a question for you: If the ear can detect the difference (assuming proven by the ABX), why can't we measure it, either at the output of the DAC, or in the listening room with a microphone? Is it that the measurement device (in this case the ADC) simply isn't resolving enough (THD+N, clock stability, etc), or is it that the measurement device is simply measuring the wrong thing, and therefore not fit for purpose? If the latter is the case, then my earlier suggested loop-back tests will prove pointless - I could get the best-measuring ADC on the planet, and it still wouldn't find any difference between the analogue outputs. I would only ever do an ABX if I were confident that I could still hear audible differences with the final setup. For example, before the previous ABX, I tried putting a preamp (a Pass Labs X1) into the chain to give us the option of taking analogue captures in real time. But it totally screwed up the sound, so I insisted on a direct DAC -> power amps path for the ABX. Mani.
  7. I've got the following ADCs to hand: - RME Fireface 800 (need to repair the SMPS first) - MOTU 896HD (mkI) - Prism AD124 (44.1/48 only) - Tascam DA-3000 (Shame I don't still have my Pacific Microsonics Model Two .) The Tascam should be fine for the digital captures, as there's no actual conversion going on. I'll do some DA/AD loops with my USB DAC and the other converters to figure out how they fare. Would a simple sine wave suffice, or would real music content better? Mani.
  8. The previous 10-run ABX took nearly 20 minutes to complete. Each A and B sample lasted for about 20 seconds, and then another 20 seconds for the X. So you're concentrating hard for over a minute for each run. I can tell you, doing 10 runs back-to-back was exhausting. Probably why I got #9 wrong . Mani.
  9. So, use a USB DAC with an spdif output, and capture spdif output in real-time to test that A and B are bit-identical? Any way of checking A and B are bit-identical using a USB DAC without an spdif output? Mani.
  10. Hi, Yes, I can see why this would beneficial. But during the previous ABX, I only had one capturing device to hand. We could have used it to either capture 1) the digital input into the DAC or 2) the analogue output from the DAC, in real-time during the ABX. It was absolutely critical to determine that the digital input remained bit-identical for both A and B (else the ABX would have been invalid), so we prioritised 1) over 2). In a retest, I think it would be great if we could use two capturing devices, one for digital and one for analogue captures in real-time during the ABX. Even better if I could use a single clock to synchronise them. So, I need two ADCs with great specs and wordclock inputs/outputs... Mani.
  11. I find it useful to consider this in two parts: 1. the ABX listening test itself The specific DAC, amps and speakers used for the ABX, and where they're situated, etc. are all totally irrelevant. It's a red herring on Mans's part. The only thing that matters is showing that the DAC received bit-identical signals when replaying A and B. The digital feed to the DAC was captured throughout the ABX, and it was proven that the DAC had indeed received bit-identical signals throughout. And yet I heard consistent differences between A and B, as shown by my 9/10 score. 2. the analysis of the analogue output of the DAC This proved difficult. I've posted the specs of the ADC used in the original analysis, which show nothing untoward. But on analysing the analogue captures, the ADC proved unsatisfactory. Mani.
  12. You don't half talk bollocks sometimes. Over 3 weeks before you came up: And then, the day before you came up, I sent you this PM: "Hi Mans, This is the procedure I'd like to use tomorrow: 1. take a quick listen together - I'd like to demonstrate a few things to you and get your initial thoughts 2. conduct the A/B/X - I've chosen the track and the bit-identical changes we'll use in the playback software - you'll be sitting in my office, controlling playback from there, and I'll be sitting in the listening room - we'll have the Tascam set to auto-record, sitting in the basement next to the audio PC and DAC, capturing the digital output of the audio PC in real time 3. ensure that the digital captures are identical - I have Audacity and MusicScope here - if you have other software you'd rather use feel free to bring your laptop along with you 4. capture analogue outputs (test track plus tones) a. directly from the DAC, using the Tascam b. from the speakers, using my Earthworks microphone and portable Korg recorder 5. analyse analogue outputs - we could either attempt to do this here or you could take the files away with you Obviously, there's no need to go on to step 3 unless you're convinced there really are audible differences (either because you hear them too, or because I manage to demonstrate that this is the case in the A/B/X). It'd be great if we can get through all of this tomorrow, but really only need to get through 1 and 2 as a must. See you tomorrow! Cheers, Mani." Your reply: "Sounds like a plan." Mani.
  13. Hi Paul, Yes, any retest would use streaming vs. local playback using Roon. I reckon a 10-run ABX would take around 10-12 minutes. I'd go for 3 of these in total, with a small break between each. This would give a total sample size of 30. Would you agree that a score of >25/30 could be taken as a positive? There was no issue with the digital feed - it proved that the DAC received bit-identical signals during the ABX, where I scored 9/10. I used a Tascam DA-3000 ADC for the initial analysis of the analogue output of the DAC. Here are its specs: How much better would the ADC need to be to be acceptable? Absolutely, and hence this thread. I'd video the entire test in both the listening and control rooms. (Capturing the sound with a decent microphone in the listening room might prove useful during analysis too.) Mani.
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