Hi Guys,

I'm back working on some old classic 80's metal projects in S5 and S6 and am wondering something...  Is the 64-bit mix engine going to be an improvement over what I'm hearing when playing back during real-time mixing with the 64-bit engine check-box unchecked?  Asked another way, I assume I'm hearing 32-bit during playback and am not experiencing the benefits of the 64-bit mix engine, is that right?  I'm asking because I was never able to get the 64-bit mix engine to engage due to a DirectXer limitation with the Synth Rack.  I'd need to (re)install Drums Superior 1.x as a native VST, and don't want to risk doing that on these old, fragile systems unless I thought the benefit may be worth it in order to engage the 64-bit mix engine.
 
I'm hoping to achieve a bit more clarity & smoothness in general, and less digital harshness in the upper-mid/high frequencies.  I vaguely recall the 64-bit mix engine doing exactly that but it was so long ago when I tested it on these old systems I can't recall for sure.
 
Sonic
 
Update: I wonder what would happen if I left DFHS registered in DirectXer and just installed DFHS as a VST directly in Sonar as well. And then only use that native VST registered inside Sonar so I should in theory be able to turn ont he 64-bit mix engine.

I am confused. You didn't say if you are working in 32 bit or 64 bit Sonar! If you are working in 32 bit, the old sales pitch from Cake said that you would have some benefits with the 64 bit engine checked. If I remember correctly, the noticeable differences would be in the reverb tails being smoother, delay trails being smoother and clearer, but no real discernable difference in the core 32 bit audio.
Since I switched to 64 bit, I can't even get some of my projects to load in 32 because I'm using past the 32 bit RAM limit. Plug in instruments have gotten bigger these days! Even drum programs have become huge with the advent of 64 bit.
I hope that I am remembering correctly and that helps you out.

The 64 bit mix engine refers only to the level of mathematical precision used when doing the calculations required for mixing the audio. When turned on, Sonar uses 64 bit mathematical precision; when turned off, it uses 32 bit mathematical precision. In most circumstances, there would be no audible difference because 32 bit precision is "plenty good enough" for this task. So it is not likely going to be worth it to go to any significant effort to make the 64 bit mix engine work if you are encountering issues with it turned on.
 
This setting is independent from the difference between 32 and 64 bit operating systems, which impacts the amount of accessible RAM. It is also independent from the bit depth of the recorded/generated audio. All three of these things use a number of bits to measure them, which can be confusing and make them seem similar, but they are not the same thing. The mix engine can be set to use either 32 or 64 bits regardless of the operating system or the bit depth of the recorded/generated audio.

SonicExplorer
Asked another way, I assume I'm hearing 32-bit during playback and am not experiencing the benefits of the 64-bit mix engine, is that right? 

 
Not really.
 
When playing back what you hear is dictated by your interface, the majority of which operate at 24 bit and in the real world, this can mean the effective bit depth is around 20
 

Thanks guys.  I'm using a 32 bit platform, they are old W2K and XP boxes.

I understand the 32 and 64 bit platforms as being a different subject than the 64-bit mix engine, no confusion there.
 
After pondering this further, I *think* "mix engine" may not be a good term?  Audio engine maybe is better? In that context, I would be hearing the 32 bit engine if the selection is unchecked, and 64 bit otherwise. So maybe that answers my own question??
 
As for a difference in audio quality, I could have sworn when I ran preliminary A/B mix tests when S5 was first released that I could hear a difference in clarity and smoothness.  Just an overall better sounding result with the 64-bit mix engine. I want to say the result was smoother and punchier, just overall higher-end professional sounding.  It was subtle but if you are a picky person it was definitely noticeable, I could hear it using just an RME and BAS 20/20 monitors. But I simply can't recall back that far to be honest.
 
I wonder what will happen if I try to install DFHS in Sonar's VST wrapper/manager (or whatever it is called) while leaving things currently registered in DirectXer as well?   Wonder if it will blow something up in a bad way.  As long as I don't try enabling both in the synth rack at the same time?  Any thoughts or guesses??

SonicExplorer
 
As for a difference in audio quality, I could have sworn when I ran preliminary A/B tests when S5 was first released that I could hear more clarity and smoothness.  Just an overall better sounding result with the 64-bit mix engine. I want to say the result was smoother and punchier, just overall higher-end professional sounding.  It was subtle but if you are a picky person it was definitely noticeable. But I simply can't recall back that far to be honest.
 

If you have a single track that started in the analog domain (including sample libraries!), it's inherent noise will absolutely bury the level at which 32 bit calculation errors start to appear. 
 
Since in this case the errors do not accumulate over time and do not accumulate rapidly, there are simply not enough calculations done on a single track in the mix engine* to raise the error level enough to be anywhere close to the noise already in the tracks, much less audible.
 
And obviously adding multiple tracks like this together will not make calculation errors add faster than the noise from the individual tracks.
 
In fact most of the 32 bit calculation errors won't even make it into 24 bit audio output, much less be above the noise floor due to other causes, much less be audible.
 
You will find people who believe they hear a difference, but inevitably they are not using a reliable method of comparison and what they claim to hear and the circumstances where they claim to hear it simply do not match what the calculation errors would sound like if they were audible.
 
 
* there are circumstances where 64 bit calculations are necessary due to the extreme number of calculations done, but this is not one of them.

Some of that admittedly went over my head a bit.  Other than to say I got the general message as being I won't hear a difference to speak of.   If it helps clarify my situation any, I'm using tracks originally recorded at 24 bit 44.1KHz.  Mixing down to 32 bit and then mastering down to 16.   DFHS (samples) for drums, analog bass, quasi-analog guitars (often Kemper) and vocals.  Hard rock style.
 
Sonic
 
 

SonicExplorer
After pondering this further, I *think* "mix engine" may not be a good term?  Audio engine maybe is better? In that context, I would be hearing the 32 bit engine if the selection is unchecked, and 64 bit otherwise. 

Actually "mix engine" is the better term, because word length only comes into play when mixing two or more tracks. If you're just playing back a single track with no modification, then there is no benefit to greater mathematical precision. It's only when modifying the audio by summing tracks or using a multiplier to alter their levels (e.g. faders, compressors, EQ) that those calculations can affect the outcome.
 
Mathematically, it's actually quite similar to how your property taxes and bank interests are calculated: when real dollar amounts are multiplied by some rate multiplier, the results are stored in imaginary currency (millicents, or thousandths of a cent). These are intermediate values that will never appear on a tax bill or bank statement. That extra precision reduces the overall rounding error, so that when those numbers are ultimately expressed in real currency the cumulative error will be less than a penny.
 
32- or 64-bit calculations do that for audio, making errors insignificant to the final result. As noted above, by the time it gets to your audio interface it's essentially 20- or 16-bit resolution anyway. Given that even 32-bit audio is overkill, there isn't even a compelling reason to use the 64-bit engine. You will not hear the difference, any more than your bank statement would be different if the bank used microcents instead of millicents.
 
 

There are many good explanations in the internet why 16bit/44.1kHz  (when down-sampled correctly) is sufficient for music. But I have seen only one good scientific and statistically correct explanation why "audiophiles" can distinguish between 24/96 and correctly produced from it 16/44 (so yes, that is possible, but...): if some part of analog equipment really can output hi settings, but that hit the limit of another analog equipment in the chain, "hi quality" signal produce more distortion then "normal" quality signal. Since the difference is "subtle", the effect is wide frequencies noise like and psychologically people do not expect worse result from "better" material, that is claimed to be "good difference". Also noise is actively used to change the sound, to imitate "warmth" (old analog effects) and "smooth" (dithering). So distortion triggered noise can easily be perceived as intentional improvement.
 
It is relatively easy to calculate from dB level changes in particular project what "error" can come out when using 32bit instead of 64bit. It should be like (gain -30)->(track +40)->(bus - 30)->....->(master +30) to come under 24. Probably for reverb route (with low level sends, convolutions, heavy compressions and other tricky algos) such signal "downgrade" is practically possible to achieve. But I think perceptible difference (as I wrote before, the direction is unclear) with hi probability comes from:
* bugs in software (32/64bit code is at least partially different, at least converted to processor code)
* completely different routes in software (f.e. recent discussion why Sonar -> 24bit WAV -> 24bit FLAC can be significantly different from Sonar -> 24bit FLAC).

Hmmm...  I did a lot of reading on the whole 32 vs. 64 bit mix engine last night and still came away not knowing what to believe.  On paper it seems not realistic to hear a difference in most scenarios, but in practice some people claim to hear it.  
 
If enough things are rounded, eventually the decimals can add to pennies which can add to dollars, it all depends on how you group and round, and how many times that transpires.  Being an old school analog relic I just don't know enough about the inner workings of this digital stuff.
 
And not to derail my own thread, but I also read a comment last night that said XP sounds better than W2K.  Which really left me scratching my head as I was unaware one OS version from another by itself could change the quality of sound.  Huh??