Chris A

My answer to your question isn't based on simple ideas such as "I don't like it", "it doesn't do 'X' that I want it to do, custom for my tastes", "the music itself isn't consistent enough to bother with this", etc. These are simple answers to your admittedly simple question. The truth is that I've used these firmware packages initially to only set channel delays and initial channel gains (due to the combination of loudspeaker placements in-room, differing loudspeaker configurations--including 21 ft internal path lengths for subs, differing insertion delays and gains of the three different DSP crossovers used in series with a preamp/processor, etc.)--because these packages do those two functions fairly well and more quickly than I can do it manually. I manually copy these two (vector) settings from the "room correction" app, but discard the rest of the most important parts: amplitude and phase corrections, i.e., the transfer function corrections. I've found that all of these packages are telling the user to place the measurement microphone much too far from the loudspeaker front baffles in-room--at the listening positions (LPs)--and therefore are mixing significant amounts of non-minimum phase artifacts from room acoustics with the minimum phase response in their upsweep measurements. Then the app's internal algorithms fail to separate out the non-minimum phase portions (by using techniques like non-flat excess group delay response to avoid trying to correct these frequency band areas, etc.) and are trying to EQ/phase correct non-minimum phase room reflections--that cannot be EQed. To date, all the apps I've tried have this disease. The loudspeakers I use in a 5.1 array all have full-range directivity, i.e., the ratio of direct to reflected acoustic energy is above some threshold that the human hearing system needs to hear phase fidelity in-room, above the room's so-called Schroeder frequency--where the concept of direct-to-reflected energy has meaning. I tried an experiment once with a fairly capable commonly used app on my manually dialed-in setup. The experiment would show that the apps would do nothing to the transfer function response if it was successfully rejecting non-minimum phase in-room reflections. This is the first criterion necessary to prove that the app could successfully use the measurement microphone distances so far away from each loudspeaker's front baffle (thus mixing in significant levels of room reflections). The apps uniformly failed this test miserably, and they all failed precisely where the physics says they will fail: right around and slightly above the room's Schroeder frequency. All the apps try to correct this region via attenuation of amplitude response, leaving the setup sounding overly (and unacceptably) "thin". It's interesting that the apps I've used all apparently fail this test at the same points in the frequency spectrum, and none allow the user to move the measurement microphone to do one loudspeaker at a time at 1m distance, then later combine with measurements at the LPs to get accurate channel delays and channel gains. Chris Askew

(I realize this thread is presently bit old, but I think it's still right on topic, so I've chosen to revive it rather than just ignoring it.) I've been using Fabfilter Pro-MB for some time now to reverse some of the effects of music track dynamic compression during mastering (but not mixing, of course). I've found some interesting tidbits of information using it: 1) Dynamic expansion with a good multiband upwards expander (like Pro-MB) is possible if the dynamics of the music track haven't been completely crushed into oblivion. In DR Database terms, this means that if the music track has at least a 6-8 dB rating using the "TT Dynamic Range Meter" (the standalone version or as a plugin for foobar2000), you have a reasonable chance of a good listenable outcome using multiband expansion. The maximum DR ratings that can benefit from expansion seem to be around 13-14 (dB-crest factor) on the DR Database scale. Any tracks compressed to lower dynamic range values seem to be "lost causes". It's much more productive to go on a hunt for a higher dynamic range version of the recording rather than trying to use a multiband expander. 2) The plugin settings used to expand tracks are usually most successful in increasing dynamic range in the higher frequencies of a track than the lower frequencies below ~100-200 Hz. This means that the crest factor ratings of the tracks from the TT DR Meter may not change very much (due to the fact that crest factor is really measuring bass dynamic range, but not really higher frequency DR), but the tracks themselves will present a much more crisp and forward sound quality for dynamic transients--like ride cymbals, crash cymbals, bells/cowbells, glockenspiel, all handheld percussion instruments (particularly latin instruments), string attack transients, marimba/vibe strikes, drums, and human voice transients. 3) The "steeliness" of string orchestras used in lush pop string arrangements and mass string orchestral scores (classical) will largely be suppressed if using the multiband expander carefully. This was a big surprise. 4) Any human voices, particularly female voices, will begin to sound much more realistic and without typical harshness that comes with listening to recordings having compression applied during mastering. This was the biggest surprise of all in my explorations using the expander. 5) The albums that respond most strongly and easily to multiband expansion seem to include those that had analog compressors applied during mastering (e.g., early-late 1970s albums), which apparently used continuously varying nonlinear compression curves without a sharp knee breakpoint/thresholding applied during mastering. 6) The music genres that seem to respond most strongly are funk, rock, folk, jazz (including smooth jazz), progressive rock with lots of drums/percussion, dance, and related genres. Those genres that seem to respond with more difficulty include smoother music genres having lots of midrange energy (i.e., ambient, new age, classical string orchestras, etc.). 7) All tracks that have used multiband expansion need to be adjusted after expansion using parametric EQ demastering. __________________________________________________________________________________________________________________________ It's clear to me that the use of a multiband dynamic range expander is now standard equipment for my typical demastering tasks that I perform on most of my incoming discs. I don't recommend trying to do expansion "on the fly" (without review and adjustment of expander settings track by track) unless extremely mild expander settings are used, which leads to barely audible subjective differences in the compressed tracks. Using an expander offline and taking a little time to get the setting right to get the best and most audible results is my strong suggestion in using these type of plugins. However, the task only has to be done once for the music tracks--then saved for future listening, instead of having to set up a custom string of plugins and parametric EQ settings each time a music track is played. Chris

Next topic of conversation...? Chris

Hummm... I don't believe that's true if mimicking the FIR phase response is part of the "equivalent set of parametric EQs". PEQs only directly affect amplitude response, and indirectly affect phase (i.e., the minimum phase properties of IIR filters). But if you ignore phase, you can get close to mimicking the amplitude portion of the transfer function. It won't sound the same as the FIR case, however, if FIR phase correction was as large as ±50 degrees (about), which is approximately the minimum phase deviation that's audible in the midrange band under nominal room conditions. If using headphones, all bets are off. Do I believe that violates what Mitch Barnett provided (,,,again, a link would be nice here...) in apparent confidence? That's actually debatable, since the PEQs are only half of the transfer function. Chris

I guess I have to say that this isn't the way that I envisioned becoming informed of all the back stories presented in very fragmented fashion here. If you make a comment about back history, the courteous thing to do is to provide some sort of valid link supporting the comment you're making. If you're too lazy to do this, then perhaps you shouldn't be taking the time to post to the thread at all. It's actually very discourteous to the readers trying to understand and perhaps agree with your position(s). Without backup links, I think it breeds negative reactions from those not immediately conversant on all the nooks and crannies of any apparently argument-nullifying counter arguments. It would be nice to get a link to the "DAC uses DSP" comments. I'm thinking my comment earlier about the DAC design potentially trying to correct for hard clipping might be a reason why the DAC sounds different (and that doesn't necessarily equate to "worse"). I'm currently thinking the spurious "DAC with DSP" comments are an allusion to that potentiality. As for the supporting arguments for the manufacturer (and once again, I've seen the reviewer's YouTube video in question in its entirety): it never appears to rise to the level of abuse that I see every day elsewhere. I can't imagine anyone taking real umbrage with what I saw/heard...but it is quite easy to imagine a manufacturer trying to suppress opinions they don't like. You'd have to be really spring loaded by prior events not related directly to that particular review to take legally imperiling action to that review. So it has to be a breaking-the-camel's-back situation somewhere to initiate all that we're seeing from the company. I don't see how to give the manufacturer the benefit of the doubt. Calling a spade a spade is appropriate in this situation, unless a great deal more information is being hidden by one or both parties. The manufacturer had other courses of action to take besides the legal one they are apparently taking. Why would they pull the big red lever on this? Occam's Razor apparently applies...once again. Chris

Has anyone talked about something like a "go fund me" legal defense for either case? That seems to me to be an effective way turn the tables on any company misbehavior. Folks with higher levels of disposable incomes that typically buy those type of products may be willing to chip in. Chris

I didn't have any inking that was the case. But if you commented and then seem not willing to share enough of your implied parallel experience to understand if it was truly a parallel experience, I do wish to understand your comment. Chris

Yes, I think that few have missed your points.

Please elaborate. By the way, I did watch the YouTube review of the device. There's nothing there that's defamatory. It's all explained from a subjective viewpoint--and everyone has an opinion. (And it's interesting that there are no demonstrably falsified statements based on measurements at all, etc.) I guess I don't have to remind anyone of the originating laws of the US (i.e., the Bill of Rights) in this that does make it much more difficult to sue someone for expressing their opinions--even online (assuming that the implied litigation is intended for the US legal system--and it may be British, etc. which have a much lower bar for this sort of thing).

Really? I believe I could. What DAC costs the company ~$19,500 USD to build...or even a tenth of that? These boutique equipment guys could simply have posted their own rebuttal on-line and left it up to the prospective buyers to decide. It would be a bit more refreshing, in fact, that they would dare to elaborate on their gear's technical approach and outcome for the typical buyer to read what they're actually trying to do (and I think there could easily be more to that story in the realm of "DAC demastering" of severely clipped source music albums and tracks that might be revelatory for prospective buyers behind that design approach). Note that I have seen cases where a relatively inexperienced reviewer has really missed the mark on what the manufacturer was trying to accomplish (and I believe one or two of of them were actually named above), but nowhere (except the two cases cited, above) have I seen a manufacturer simply threaten an online reviewer with litigation to take down an entire review--and without detailed reasoning and rebuttal points. This is plainly bad manners for the manufacturer--and makes me think that they want to intimidate their audience in the boutique gear marketplace so that they can continue to charge 10x or more than it costs them to build and ship a piece of hi-fi gear. Think of it this way: would a very large manufacturer like Yamaha, JBL/Harman, Klipsch, etc. ever threaten a single reviewer based on a single negative review? I seriously doubt it. They would probably just ignore the reviewer's posting. Chris

I think it's wise to recognize the difference between bus jitter and DAC clock jitter. In the past, incoming DAC data streams were susceptible to clocking issues on the USB bus itself that connects the data storage device and the playing hardware (DAC and its clock, etc.) since there wasn't an effective buffer between the DAC and the incoming USB bus. DAC clock jitter has always been the performance parameter to pay attention to--along with the analog output sections of the DAC itself, and the effects of diaphragm movement of your loudspeakers (i.e., direct radiating loudspeakers). The effects are the same: side-band-inducing modulation distortion--which is audible. Chris

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I'm late to the party. Nevertheless... I'd recommend taking a look at "affect bias" mentioned in Thinking, Fast and Slow, pg. 103 by Daniel Kahneman (the 2002 Nobel prize winner in Economics--for decision sciences). Also, I recommend Rational Choice in an Uncertain World (1999) by Hastie and Dawes for a more "operational" viewpoint. This has a very deleterious effect in the design of any system of any size, resulting in the types of systems that we see everywhere today, i.e., an example-rich environment of consistently poor decision making...and resulting poor outcomes. It's also essential reading in the rise and fall of business organizations (business cultures all have their unique sets of spoken and unspoken heuristics and biases that vary even within their own organizations). A list of cognitive biases can be found here: https://en.wikipedia.org/wiki/List_of_cognitive_biases It's a long list. A few of those have application to the present topic. Chris

See: Corner Speaker Placement excerpts PWK.pdf You're describing cases #1 to #2 almost exactly. Note that the rule of thumb is that below the room's Schroeder frequency (usually ~200 Hz), the 1/4 wavelength cancellation frequency is also dominant as measured from the floor to the bottom of the loudspeaker. Chris

I play Jean-Luc Ponty (demastered) tracks weekly. I started listening to Jean-Luc with his Civilized Evil album, where I believe he really hit his stride for the remaining albums he's produced. Here's an anthology that will give you an idea of his offerings. I'll start you at the second disc of this anthology (about 1979). The albums beyond this point are what I believe that define Mr. Ponty's real contribution to the genre: Another favorite that's still played quite often--Billy Cobham's Crosswinds: This album features John Abercrombie on guitar, the Brecker brothers on sax and trumpet, George Duke on keyboards, Garnet Brown on trombone, and Lee Pastora on latin percussion, in addition to Cobham on drums. I find this album to be far more listenable than Cobham's Spectrum, which I also play occasionally. I recommend especially The Pleasant Pheasant, Heather, and Crosswinds. Jeff Beck's Blow by Blow is a classic fusion album (so is Wired, but this is much less played in my house). I don't generally play Miles Davis fusion albums, but I do play those associated with Davis during that time: Return to Forever (their Blu-Ray video is spectacular) and the first two albums of the Mahavishnu Orchestra (John McLaughlin and Billy Cobham, et al.). Birds of Fire seems to have taken on a cult status: Jaco Pastorius's Jaco is also a cult classic (much better to listen to after demastering to reverse the bass attenuation found on distributed discs). Marcus Miller's Silver Rain is quite good. Hiromi Uehara's ("Hiromi") albums are absolutely spectacular (all of them): Bela Fleck and the Flecktones Flight of the Cosmic Hippo is also well known among the audiophile community. This album is much better after demastering to restore the bass lines. That's just the fusion artists off the top of my head that I play quite often. There are many others... Chris