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Low Level Detail: An experimental search and test.
Low Level Detail: An experimental search and test.
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Old 9th May 2015, 09:58 PM   #61
Pano is online now Pano  United States
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Low Level Detail: An experimental search and test.
Got it. However mostly I'd hope to test single drivers to know if they can retain low level detail or not. Once it gets into multi-way, like the JBL EON, it gets complicated. But it may give an idea of the total system.
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Old 9th May 2015, 10:43 PM   #62
Charles Darwin is offline Charles Darwin  United Kingdom
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Originally Posted by bwaslo View Post
BTW, maybe not exactly for this thread, but I think some mention should be about "hidden detail" and "perception of hidden detail", as they aren't likely to be the same. Different things might make music seem more detailed, and some won't have anything to do with more accuracy or S/N. So something that shows more perceived detail might even have less "detail" that might be determined mathematically. A good example is SET tube amps and my system speakers. The SETs distort like hell (all that "clean first watt" stuff, when measured, is still miles from even approaching a chip amp's distortion on any harmonic), and their response changes with speaker load. But either the distortion or the change to eq gives more perceived detail, small things just get noticed more.

BTW, what would happen if all the reviewers (the ones who "heard things" they'd "never heard before" on their old records, after using a new component), would they hear those same things now if they listened again with the system restored to how it had been before? Would those thing in the recordings be inaudible, unheard, again? I doubt it. I think with ears, it's a matter of getting things noticed as much as it is about getting noise and distortion down.

I'll stay tuned...
Bill
I think may be the small detail is being artificially enhanced by highly distorting SETs.

An externally hosted image should be here but it no longer works. Please upload images instead of linking to them to prevent this.

(I hope this works and the image is from and presumably owned by Rod Elliott of ESP.)

The way waveforms add it is the higher frequencies which clip first.
In the case of SETs if I remember correctly that is mostly 2nd harmonic and generally even order which is musically related to the 1st harmonic (aka fundamental). Basically a new signal not present on the recording is generated one octave up from the original and the 4th harmonic would be two octaves.

Musically the equivalent would probably be playing chords when the composer asked for single notes.


As for newly discovered details and just speaking for myself once I hear a previously missed detail when replaying a tune on another system I hear it all the time on most systems. Probably not as clear or obvious but it is still there usually.
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Old 10th May 2015, 02:08 AM   #63
bwaslo is offline bwaslo  United States
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Low Level Detail: An experimental search and test.
Hi Mitch, I just ran into this post. Something in the DiffMaker help files tends to be almost always overlooked. The length of the tracks sampled should usually be on the order of WELL under 60 seconds (I usually used 10 seconds), because the memory required and the likelihood of complications gets astronomical quickly. DM oversamples (a lot), does scads of transforms, comparisons, and all that, so memory gets eaten up at a rate on the order of many video editors. Besides, for comparisons done without locked record/play clocks (on all signals), the biggest difficulty is usually sample rate wandering. DM handles to about 3rd order wobbles (such as a "increasing, decreasing, then increasing again" case), but beyond that all bets are off. 60 seconds of recording with unlocked clocks is unlikely to vary in such a simple way and it only takes a ridiculously small sample time error to blow the whole deal. Also the frequency response correction trick (EQ) it can do doesn't do well with rate variations of any type, really.

(BTW, I'm not developing DM anymore since about 7 years, it did what I needed it to do then for my own investigations, and further work or support isn't really in the cards. But thanks to all for trying it!).

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Originally Posted by mitchba View Post
Just a comment on DiffMaker...

I have used DiffMaker and Audacity several times for null or difference testing with equal results. Here is one example:
Computer Audiophile - JRiver Mac vs JRiver Windows Sound Quality Comparison

There seems to be a few quirks using DiffMaker that many using the program have run into. I documented details here and here, but in summary, one issue for me was processing recordings greater than 60 seconds can randomly crash the program.

Another is in order for the time/sample alignment automation to work reliably, somewhere in the beginning of each set of samples must be an identifiable transient so the software can pattern match the two tracks, and it's within a limited time window as well. Otherwise, the software gets confused, even off by one sample will render the results useless.

Archimago found similar issues and came up with his own test protocol to bypass these: Archimago's Musings: PROTOCOL: [UPDATED] The DiffMaker Audio Composite (DMAC) Test.

Hope that helps.
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Old 10th May 2015, 02:14 AM   #64
Pano is online now Pano  United States
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Low Level Detail: An experimental search and test.
Thanks Bill. I will try to keep the clips to 10 seconds in future.
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Old 10th May 2015, 04:23 AM   #65
mitchba is offline mitchba  Canada
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Quote:
Originally Posted by bwaslo View Post
Hi Mitch, I just ran into this post. Something in the DiffMaker help files tends to be almost always overlooked. The length of the tracks sampled should usually be on the order of WELL under 60 seconds (I usually used 10 seconds), because the memory required and the likelihood of complications gets astronomical quickly. DM oversamples (a lot), does scads of transforms, comparisons, and all that, so memory gets eaten up at a rate on the order of many video editors. Besides, for comparisons done without locked record/play clocks (on all signals), the biggest difficulty is usually sample rate wandering. DM handles to about 3rd order wobbles (such as a "increasing, decreasing, then increasing again" case), but beyond that all bets are off. 60 seconds of recording with unlocked clocks is unlikely to vary in such a simple way and it only takes a ridiculously small sample time error to blow the whole deal. Also the frequency response correction trick (EQ) it can do doesn't do well with rate variations of any type, really.

(BTW, I'm not developing DM anymore since about 7 years, it did what I needed it to do then for my own investigations, and further work or support isn't really in the cards. But thanks to all for trying it!).
Hey Bill, thanks for your DM software! Many folks have used it with good success. Sure, understood on the 60 seconds. I have been getting reliable and repeatable results with around a 30 second test file as did Archimago. It has been fun! And very revealing :-)

Have you considered open sourcing the software on GitHub? As a fellow software developer, I know other software developers and audio enthusiasts would be interested in carrying the DM flag forward, if you fancy that.

All the best, Mitch
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Old 8th September 2018, 05:32 PM   #66
oivavoi is offline oivavoi  Norway
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Bumping this. Fascinating topic, and difficult to find any reliable measurements at all! Did anybody investigate this further?
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Old 8th September 2018, 06:29 PM   #67
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Low Level Detail: An experimental search and test.
I let this drop because of a sudden move of location of about 8000 kilometers. I never picked it up again because I remembered the results as inconclusive and the process as difficult. If anyone else went on with the tests, they can report them here.
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Old 14th September 2018, 02:51 PM   #68
chris661 is offline chris661  United Kingdom
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Originally Posted by Pano View Post
I let this drop because of a sudden move of location of about 8000 kilometers. I never picked it up again because I remembered the results as inconclusive and the process as difficult. If anyone else went on with the tests, they can report them here.
I did something with my mixing desk a few years back. It has multi-track recording capabilities, so it's easy to loop and re-loop things - just move the slider back to the start and you've got the same section of pink noise over and over again. Handy.

So how about this as a test:

- Record a section of pink noise within the desk (that way, we're using the same bit each time)
- Play that pink noise through a speaker while recording the mic input
- Seperate channel - mix the pink noise with a swept sine, or whatever else
- Play noise + sweep through the speaker, record the mic input
- Import into Audacity
- Invert one recording, and sum
- Ought to leave you with a sine sweep
- Import into REW
- ????

I think the think to do there would be to also record the speaker playing the swept sine tone without pink noise, and then you've got a comparison - low level sweep vs low level sweep plus high-level noise.


From what I can tell, that's holding as many things constant as possible - all we're doing is introducing (repeatable) pink noise while doing a sweep.

I'd probably do it close-mic'd so SNR improves with regards to outside acoustics, noise, etc. Anything that gets recorded will screw up the measurements.

Not really in a position to do much audio-related stuff right now, but once things settle down this is something I'd like to get back to.

Chris
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Old 16th September 2018, 04:10 PM   #69
Pano is online now Pano  United States
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Low Level Detail: An experimental search and test.
That seems like a good idea Chris. I like the idea of recording the low level signal alone as a comparison. The main stumbles I found were getting the files lined up at the correct staring point and also getting them level matched. Level isn't too hard, if you record one after the other.

Yes, close miking is required if you don't have an anechoic chamber. We are really just concerned with how well the driver can reproduce low level detail. In this test it is low level detail buried inside a higher level signal - but maybe just a very low level comparison of a single signal would tell us a lot.
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Old 16th September 2018, 05:07 PM   #70
benb is offline benb  United States
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I wonder if you could use that .wav file diff program that was discussed a few years back.
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