Summing device

[Riad]

I have a PT HD2 Accel system going out Apogee AD16-x and DA16-x converters both with X-HD cards. I use a Dangerous 2 Bus.

The one thing I noticed is that the D2B seems to focus the mono channels much better. So kick, snare, bass and vocals appear to be sitting clearer and more centered.

I would be willing to have a people come up to my studio and we can do all kinds of test, if at the end the D2B doesn't make a difference I'd sell it.

Rob

[PTUser NYC]

one level I've noticed that stays consistent in mixes with powerful drums is that the kick and snare look like they average around minus 7 to -10 dB if you solo them--or is that the entire drum submix?

Cool, thanks. I give some weight to your posts because they disagree with what I already believe, were well conceived, and obviously passionate, and you talk about mixing ITB as a choice you make a good deal of the time too, even with the summing devices available.

From that I surmise that you're honest, not fanatical, not basing your argument around an intelectualized point of view, and just describing what you've heard without too much bias.

I guess I assume that in your studio, what you are saing is "true." I'm trying to figure out how what you've said can be true, and how what I believe can also be true at the same time. I like to challenge my beliefs, because a broader theory expands my own understanding.

So, the first thing I thought about was my old color argument. That "color" is more than THD+N, that it includes ANY non linearity of the system, like the way a good transformer colors sound with low harmonic distortion levels, as one example.

Then I got to thinking about levels. I was half hoping that you'd come back and say that you track really hot, with peaks in the vocal track around -1dbFS or something. Then I could reason that the analog summing box was doing a better job of distorting. Then I could also reason that perhaps the gain staging into the box was giving you better headroom in summing.

Unfortunately for my easy answer, and most fortunately for your audio product, your levels are appropriate. I've found that tracking and mixing too hot is the surest way to get Pro Tools to sound crappy. Obviously, the sound of the mic preamps working 18db over 0dbVU to get a 'full signal' is a problem before Pro Tools even sees the audio. Then a lack of headroom in plug ins and the mix bus (headroom before clipping, not headroom in the master fader) compounds the problem.

My ITB mixes usually peak around -8dbFS or so before the mix bus processing, which generally includes the Rennaisance compressor taking away less than 2db of gain reduction, and usually a lot less, and then quite a bit of output gain to bring the level up to full scale. I often follow this with another limiter, but you get the point.

This way, the final stereo mix DOES peak at -0.1dbFS for me, but the headroom in the channels and summing of Pro Tools (before the stereo mix is 'normalized'') is usually over 8db.

Seems like you're doing the same thing.

So I guess I'm back to square one. There's some color that the summing mixer brings that's pleasing, and unifying to the mix.

I guess what's left is to wonder if there is some sort of stereo processing that could give a similar effect.

Thanks for the good information, and giving me something to think about. I still think the emperor might be naked in regards to SUMMING, but color is color, and good color is good.

[punk]

[quote I don't base my mix bus levels on the LV because the low end instruments seem to add more energy to the meters.

[/QUOTE]

Perceived loudness can be improved by careful EQing of the bottom end. Pultec type EQ's can be dangerous as it's easy to hype the same low frequencies all over the mix.

In response to PTUserNYC, if you hear it then it's 'true' for you. No matter how objective we can try to be there are so many variables that can make any test subjective.

I track as hot as possible without clipping. As far as I can remember that is the 'official' digidesign position. After reading the White Paper on the TDM mixer I also became a 'lower the mix buss' type instead of leaving it at unity and lowering track faders, which was a popular idea some years ago. I THINK this sounds better, but I'm sure digidesign will say it shouldn't.

Someone, much cleverer than me, once reminded me that the PT mixer is unique as all different mixers are unique. They all have their own 'colour'. If you like the PT mixer you're ahead of the game I suppose.

I don't use limiters much while mixing. Sometimes I have trouble when a reverb plug will clip, I'll use the L1 ahead of it. When I'm 'psuedo-mastering' I'll use the L1 set to -2 at most.

IMHO, the McDSP Analog Channel(AC1 I think) is an example of a plug that creates a realistic 'analog' feel in software. I'm on MIX so I don't know about the newer plugs available for HD.

And I can't say I know exactly why I should like going OTB. I can't use some slide-rule equation to 'prove' my position. But we can all benefit for shared experiences of what we're hearing.

byron

[jtoole]

I admire your initiative, yet I wonder if your money is well spent. Doing this project as a labor of love is one thing, but as a test for the validity of analog summing OTB is a different story, and it could be very misleading.

First let me say that I'm interested in audio electronics in general, and have a background in an electronics related field (embedded systems). I do not have as much experience in audio electronics (I've built a few paia kits), and I have no doubt that pro designers understand the 'sound' of the many variables that go into circuit design much better than I can. That said, I must agree w/ Bryon that to really learn you've got to try it for yourself. I'd say I'm interested in first a DIY audio project, and secondly, possible ending w/ something useful for the studio... I'm less concerned about an impartial ITB/OTB comparison. What I've learned about the electronics, analog and digital, that go into sound and music production have helped me use my studio to the fullest, and I am not the type to get into a "must have this" rabbit-hole.

What about crosstalk, distortion and noise? Will your DIY project account for these concerns? What about headroom?

I suppose I'm hoping that such a simple passive circuit w/ only resistors for components won't have too many factors to tweak. My understanding is that effectively the main variable will be the impedance relationships, and Byron provided some useful resources in that regard. In addition, my co-worker whose a EE and has an interest in audio electronics is going to help w/ these issues.

I can understand that more complex designs may sound more appealing (ie. transformers, or gain makeup characteristics) but w/ no power supply, it seems like a passive summing network can't have too much going on. I expect that the quality or benefit that I might get from such a circuit will ultimately be limited by a) limited quality of D/A and A/D, and b) quality of gain recovery pre - regardless, I'm still interested in the project for the projects sake. What factors of a passive circuit like this might I not be considering?

It also seems to me that a project like this has the potential to be tranparent enough to be useful for someone w/ good converters and something nice for gain makeup, hence the though that others might be interested in trying it. I'm also perfectly content w/ trying it alone. If it works nicely or not, I'll share those results with everyone.

It looks like I'm going to be able to get 10 PCBs for about $200... I've already got plenty of cable, connectors, and the resistors are cheap. I think the project is still likely to end up being a good deal less than a dangerous LT. If I could budget in a D2B right now I'd do that, but I've got other financial priorities.

In any case, Thanks for all the input Michael, and for the interesting thoughts from everyone on this thread - Its absolutely appreciated!

jt

[jtoole]

Don't most set ups have some desk to route and sum multiple outputs? Then we can better discuss the subject from what we hear, not what we think we might hear.

I don't currently have an outboard mixer. I sometimes patch outboard gear w/ inserts in PT, but I primarily work ITB today.

I considered that getting a mixer might be a decent option, but a low/mid priced mixer will have low quality pres, a noisy power supply, many low spec components in the circuit, etc.

In contrast, a very simple passive summing circuit has only a few components and variables that I can try to optimize for my application. I also appreciate the idea that w/ no channel gain, pan, etc, one can still maintain complete recall from PT (w/ the exception of makeup gain I suppose).

...

Thanks for the input Byron. I am still hoping to try this project out, so I'll let everyone know how it goes, for better or worse. If you have any other resources you can recommend, its always appreciated.

Thanks again,

jt

[Bentley Ferrari]

A quick return to the other sub-thread within this thread.

I just have to say that I appreciate the approach to the summing device question being taken here by Michael James and PTUserNYC. It looks like there is a pretty convincing basis for the proposition that, in PTUserNYC's words: "There's some color that the summing mixer brings that's pleasing, and unifying to the mix." Threads of this sort so often devolve into a "my Dad can beat up your Dad" thing, where the contributors won't move off their first position just out of sheer pride. Thanks for the honest thinking guys. The best example is PTUSerNYC's response to Michael James below:

I'm trying to figure out how what you've said can be true, and how what I believe can also be true at the same time. I like to challenge my beliefs, because a broader theory expands my own understanding....

...Then I got to thinking about levels. I was half hoping that you'd come back and say that you track really hot, .... Then I could also reason that perhaps the gain staging into the box was giving you better headroom in summing.

Unfortunately for my easy answer, and most fortunately for your audio product, your levels are appropriate. ...I've found that tracking and mixing too hot is the surest way to get Pro Tools to sound crappy. ...

So I guess I'm back to square one. There's some color that the summing mixer brings that's pleasing, and unifying to the mix.

I guess what's left is to wonder if there is some sort of stereo processing that could give a similar effect.

Thanks for the good information, and giving me something to think about. I still think the emperor might be naked in regards to SUMMING, but color is color, and good color is good.

And thanks to Michael James for the following information, which contains what I think is a great idea. I started using Trim Groups myself after seeing this:

I think PT sounds better with more headroom, and it's a good idea to leave some room for flexibility in mastering. Thus, I always create a "Trim Group" that allows me to adjust the relative volume of all the elements of the mix before they hit the FX. I listen to the way the sound is affected.

Great stuff.


Mike Colucci