Bogus claims Re: OTB summing from Black Lion

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leigh
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Bogus claims Re: OTB summing from Black Lion

Post by leigh » Tue May 31, 2011 10:15 am

Someone posted a link to the Black Lion PM8 summing mixer on another board, and I was checking it out. Go on and read the first paragraph here:

http://www.blacklionaudio.com/content.php?p=36

Or, for your convenience, here's the first 2 sentences (emphasis mine):
Summing in the analog domain is widely regarded as superior to mixing "in the box." The DSP required to sum individual channels into a stereo pair is prone to clock-based errors and mathematically unrelated signal artifacts, something avoided entirely by mixing down in the analog domain.
I assert that this is categorically incorrect.

The process of summing ITB is, in fact, not prone to clock-based errors - because there is no clocking going on! The summing itself just happens one sample at a time, in what is essentially a non-realtime process. (I could illustrate this more at length - but in short, you don't need a clock to say "sum all samples at time slot 1, now sum all samples at time slot 2, now sum...")

On the other hand, OTB summing does bring your clocking into play. So, quite to the contrary of Black Lion's claims, mixing down in the analog domain does NOT avoid "clock-based errors" - it instead re-introduces them!

Anyways, I know Black Lion gets a lot of respect on this board, and maybe their products are indeed fabulous. But letting their copywriters run wild with some pseudo-science-sounding bullshit isn't doing them any favors.

cheers,
Leigh

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Post by KennyLusk » Tue May 31, 2011 12:34 pm

Not to be argumentative, and admitting I don't have the technical knowledge in this case to iterate an argument, but when I sum ITB the end result always sounds different to me than what I hear before a "bounce to track" operation. To put a word to it, there is a sort of "flattening" of the summed signal. Whereas, when I route all my tracks from my DAW box out to my mixer and record the "sum" to a single track ITB the sound retains more of a dimensional quality.

Can I explain this scientifically? The answer is "no". Can I say it is my experience? Yes.

Admittedly my converters for the past 4 years up until recently were BLA converters. And I trust the fella's at BLA to know a lot more about the engineering end of it than me. All I know is what I hear with my own ears. YMMV.
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Post by leigh » Tue May 31, 2011 12:54 pm

Hi Kenny - I have no doubt or disagreement about what you're saying. I wasn't saying at all that ITB and OTB summing are the same, or that one is better than the other.

Rather, I was taking issue with Black Lion's explanation that the difference is due (at least in part) to ITB suffering from "clock-based errors" - whereas, if anything, the exact opposite is true!

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Post by KennyLusk » Tue May 31, 2011 1:37 pm

Leigh, I do notice that when I sum (bounce to track) ITB, as my software is processing the tracks, chan. fx, buss fx, etc., my Mains buss is showing levels at the Mains. To me this could be an indication that internal clocking is participating in this bounce event somehow. Of course I could be wrong. Not much time for me to think about it right now as I'm off to my day gig, but I'm sure more TOMB'ers will chime in with their own thoughts.
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Post by Scodiddly » Tue May 31, 2011 4:18 pm

I agree with the OP - bad writing at the least.

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Re: Bogus claims Re: OTB summing from Black Lion

Post by rhythm ranch » Tue May 31, 2011 6:29 pm

leigh wrote:I assert that this is categorically incorrect.
Did you share your concern with Black Lion?

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Re: Bogus claims Re: OTB summing from Black Lion

Post by wesley.wittich » Tue May 31, 2011 8:50 pm

rhythm ranch wrote:
leigh wrote:I assert that this is categorically incorrect.
Did you share your concern with Black Lion?
+1 - It would be really interesting to see how they respond to this...

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Post by Marc Alan Goodman » Tue May 31, 2011 10:51 pm

I'd imagine you're dead right. They prob hired someone to handle the site and glanced through it while they were busy developing and building their products. I can't imagine a company that builds clocks would actually think that statement was true, or that they would be trying to mislead anyone. What would be the point?

Let them know what's up; I bet they apologize and remove it immediately. Hell, they'll probably hear about this thread tomorrow.

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Post by Jim Williams » Wed Jun 01, 2011 7:54 am

More clarity is required, that's all. It's easy to take simple statements and finish the thoughts with your own conclusions.

Yes, there is no word clock used in suming. However, there are more than one clock operating here. The system master clock is always operating even if the word clock is not.
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Post by willhouk » Wed Jun 01, 2011 9:35 am

I saw a review of a BLA preamp on Ronan's Recording show and they did something really cool. He said the preamp he had had more self-noise then he felt appropriate. He thought he'd contact the company to see if they'd send him a different pre to test. They said that the unit he had probably had a minor defect but he should review it anyway. They said if a person had bought that unit, then that would be the one they got. So, they said he should review that unit.

They seem pretty forthright, so it's probably an honest mistake.
Be well, do good work, and keep in touch.

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Post by leigh » Wed Jun 01, 2011 10:08 am

Jim Williams wrote:More clarity is required, that's all. It's easy to take simple statements and finish the thoughts with your own conclusions.

Yes, there is no word clock used in suming. However, there are more than one clock operating here. The system master clock is always operating even if the word clock is not.
I disagree that this is an issue of "clarity", or that this is me drawing an off-base conclusion.

The fact that every computer has a system clock is irrelevant here, because that is clearly not the type of clock that they meant. But even if you think that is the type of clock they meant, it would still not affect the quality of a non-real-time process, and so there would still be no "clock-based errors" with in-the-box (DSP-based) summing.

Leigh

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Post by leigh » Wed Jun 01, 2011 10:11 am

@rhythm ranch and @Marc - I haven't yet contacted Black Lion directly about this. I'll drop them a line now.

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Post by Bro Shark » Wed Jun 01, 2011 10:16 am

Point them to the thread. I know one of their guys has an account here. It'd be cool if they chime in directly.

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Post by kslight » Wed Jun 01, 2011 10:20 am

I think it can be said for many companies that you have to filter out the fluff to find facts. BLA seem to go a little crazy with the buzzwords and fluff though.

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Post by KennyLusk » Wed Jun 01, 2011 10:23 am

So in summing ITB if you are re-sampling from 96kHz down to 44.1kHz and rendering from 24 bit word length to 16 bit, the internal clock of your device is not involved?
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