Aux sends and returns in a mixer project- what's your opinion?

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boji

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So... gdiy friends, truth be told I simply don't have that much experience using aux's outside of a daw. 

For this reason I value your opinions, not only on feature suggestions, but creative examples of use, as this will help me get a better understanding of what to add or not to the modules.

For example, Abby pointed out that a hpf on the send bus may not be necessary as some fx gear would make the feature redundant.

Ian mentioned solo is not necessary, but a mute would make sense. Mutes just on the send module or also on the return?
(Edit: Assigning returns to the mixbus is the mute/on button in a way...  Same with aux sends.  ::) ::)  )  Or is there something I'm overlooking?  CV's for global aux mutes / fx mute automation?

On the creative side, I'm open to ideas.  Would a phase switch be helpful?  I can imagine flipping a verb, delay, etc. out of phase with the source might allow for some interesting results...

And lastly pan...  my 6 aux channels are mono but each pair share a pre/post fade button, so...pan's on the send (cue imaging) and perhaps also on returns (fx imaging)?
Looking over a DDA CS8 skiz today , the aux section does not appear to deal with pan, only a balancing output scheme, so perhaps I'm overthinking this...

Thanks for trudging through questions on this fairly simple part of the console... Last one (for now):  Should returns be assignable to group buses as well as stereo mix?

Thank you in advance for any thoughts you may have!
-Boji


 
There are a lot of uses for a mixer, and the nature of the workflow / task at hand will favor different features.

It sounds like you want to do multitrack mixing, but to do that, you also need to do tracking. There are also consoles for front of house live sound, live sound monitor mixing, theater FOH mix, film mixing, location stereo mixing, location multitrack tracking... you get the idea.

So, define the task better and you'll be able to answer your question better. I'd suggest that simpler is usually best, since too many features will just complicate the circuitry and make it more user error prone, but you can't make the mixer too simple that it won't work well enough for what you expect to do.

Sorry to be vague, but I've used aux sends in many contexts for different things, and they all have different requirements.
 
Thanks Mr McGuire for replying.

define the task better
True, that's kinda what I'm trying to talk out. :)  It'll be used in a studio for recording, overdubs and mix down.
You say you've used them in many contexts; I'd love any examples that might be considered unorthodox but that you've found helpful.

I'd suggest that simpler is usually best, since too many features will just complicate the circuitry
Totally with you on that, however last week I hadn't even considered the value of stereo returns. 
 
boji said:
Ian mentioned solo is not necessary,
But PFL is a must.

Mutes just on the send module
Do you mean on the Aux group? I don't think it's a necessity.

or also on the return?
I don't think it's really necessary, since you have a fader. Unless you want to have it under logic control...

Would a phase switch be helpful?  I can imagine flipping a verb, delay, etc. out of phase with the source might allow for some interesting results...
True reverb is "phaseless", unless it has a wet/dry control, but delay, flanger/phaser are phase-sensitive (actually polarity). Although a polarity inversion facility is often included in FX boxes, having one on the FX return module is a sensible feature.

And lastly pan...  my 6 aux channels are mono but each pair share a pre/post fade button, so...pan's on the send (cue imaging)
Again, I surmise you mean the Aux groups; a pan-pot on a group is typically used to route the group signal to the Master bus. But on an Aux group, it doesn't make sense IMO.

and perhaps also on returns (fx imaging)?
You need that.


  Should returns be assignable to group buses as well as stereo mix?
It all depends on your workflow. If you deliver your mixes as stems, you need to be able to assign FX to groups.
You may want to have Aux sends on the FX returns that are used for reverb, for adding reverb to the musicians foldback.
It used to be that simple mixers did not have routing facilities on FX returns and when the range grew in complexity (and price), more features were added. You really need to analyse what you intend to do.
 
As everyone has said it depends on what you are trying to do but some general points would be:

Sends:

When tracking you mostly need pre-fader auxes for foldback to artists.  In the old days there was one or maybe two of these. All the artists got more or less the same mix and as the basic tracks were usually  laid live, foldback was mostly used for overdubs. In these days of separation mania, all the artists wear headphones all the time and demand their own personal mixer for them. I suspect the solution to that problem is way beyond the realms of the home built mixer. (Dante?)

When tracking you may also need one or two post fade sends mostly for vocal FX . The ear craves reverb so artists do sing better with some reverb in their cans.

For mixdown you need auxes for FX sends and these will be mostly post fader. The question most people ask is how many auxes do I need to which the reply generally is you can never have two many auxes. In my humble view both the question and the answer are poorly phrased and tend to lead to mixer designs with far too many tiny aux send knobs.

The right answer to the question how many auxes do I need is to ask how many do you need at once on any channel and how many different FX do you want to use at once in total. The answer to how many do you need at once is rarely more than four and this is the number of aux send knobs you need per channel. The answer to how many FX do you need to use at once in total is the number of aux buses those four knobs need to be assignable to. From then on it is just down to the creativity of the mixer designer as to how this is done. Perhaps one of the simplest schemes is where there are four aux send knobs each of which is assignable to one of two buses giving 8 available aux sends. All the auxes knobs default to post fader  two are switchable to pre for foldback.

The API routing module schematic you posted on another thread is a good example of this kind of approach.

Returns

In the limit, returns can be fed to the line input of a channel so all the facilities a channel has will be available to and FX return.  So as not to use any of the precious channels in a small mixer for this purpose, simplified aux return channels are often provided. It often used to be a cut down version of the channel routing module. You rarely need to add FX to FX so the return  channel only needs a couple of pre fader aux sends for foldback - so the artist can hear the reverb. You need pan and routing at least to the master LR buses, You may also need to be able route returns to groups when using subgroups or creating stems so I would retain those. You need some means of listening to the return on its own. Destructive solo won't work because it will mute the sources driving the FX, but non-destructive solo or PFL will work. Last but not least you need some sort of EQ. Reverbs from chambers and EMT plates can have a muddy bottom so a HPF was a must (today's gear is different but I suspect there is little useful low frequency content in any FX return)

Cheers

Ian
 
As said already for performers mix.  This will require some form of talkback as well.  It could be just you using one channel with a microphone into the aux to talk to performers.  Or it could be a dedicated talkbac system in you monitor controller.

Also your Cue system ( headphone mix) could be a pile on type switch.  This allows the main control room mix to feed cues for a quick mix to performers and then if the vocalist needs more vocals, you simple raise the aux for the vocal channel which piles on to the main mix to raise that level only in the performers mic. 

This allows for a very speedy headphone mix with performers.  The downside of this type of headphone feed is your mix in the control room is effecting your headphone mix so you cant mute or change levels with out effecting your headphone mix.

 
I suspect my advice about console design is dated... (last century).

It really comes down to your studio workflow...  what do you need?

Perhaps look at the numerous classic designs to see what S/R features make sense for you.

JR
 
JohnRoberts said:
I suspect my advice about console design is dated... (last century).

It really comes down to your studio workflow...  what do you need?

Perhaps look at the numerous classic designs to see what S/R features make sense for you.

JR
+1 all good engineers look how how everyone else did it before (hopefully) doing it better.

Cheers

Ian
 
Wow getting into the 1608 Echo/Send Return modules ..they are nice. Glad I'm no engineer because I'd be hard pressed on how to improve it without going digital.

I get now that the aux section can very much define the flexibility of a console. I feel like I'm at the beginning again wrt design choices.
 
ruffrecords said:
+1 all good engineers look how how everyone else did it before (hopefully) doing it better.

Cheers

Ian
Funny when I managed an engineering group part of the tension was discouraging my engineers from reinventing the wheel every time, while my inner engineer said "lets rip the top off this and do it better"... 

We did enough of both, to keep my talented engineers (and management) happy.  8)

JR
 
ruffrecords said:
Above is a single aux pot. selectable pre-post but whose output can be selected to any combination of four aux buses, Six AUX send with 3 knobs
It's based on the ASSumption that  a channel will be sent to only one FX at a time; it was more or less valid when most studios had one main echo chamber. Today, it must be viewed in the perspective of multiple FX available, mitigated by the fact that it's much easier to process individual channels via plug-ins.
This API circuit is a testimony to studio technology of the 70's. Today, users and customers expect more.
 
abbey road d enfer said:
It's based on the ASSumption that  a channel will be sent to only one FX at a time; it was more or less valid when most studios had one main echo chamber. Today, it must be viewed in the perspective of multiple FX available, mitigated by the fact that it's much easier to process individual channels via plug-ins.
It was meant simply as an example of what could be done to  save controls. As I mentioned earlier the console design engineer's imagination is the only limit. The point is you don't have to have 8 knobs for 8 aux sends.
This API circuit is a testimony to studio technology of the 70's.
Early 70s maybe. When I was at Neve in the mid 70s we had routing modules with 8 aux send knobs. Even then I thought it was excessive
Today, users and customers expect more.
For some segments of the market that is true.

Cheers

Ian
 
Today, users and customers expect more.

No doubt about that.

But there are so many ways to accomplish that with a DAW hooked up to a modest size mixer that has a sonic signature you are inspired with.  The last thing I want these days is a 48 channel SSL to take care of.  Been there done that. 

It’s whatever works for you and gets you there fast and consistent.  I’m very happy with Relabs VSR verb plug-in.  Now I need a 32 I/O to map to my echo send and returns so to mix in the box and somehow have full recall when I need to remix.  It’s a big game we play for this passion.  Life is a compromise.
 
Quickly being able to change the HP/monitor mix to the performers is great thing  in almost any recording or live environment . I really dont like the modern digital concept of having to tab through menus to get to those setting , reaching out and touch the actual control per channel is much faster , Studio maybe not so much preasure , but live say you have a monitor feeding back ,you need to get to it fast .

Im not sure sending in stereo to fx would be much needed ,but again it all depends on how you like to work .

This idea of a personal headphone mix for each performer is a big ask from your engineer ,theres nothing worse than a barrage of requests for this or that up/down etc ,usually you try limit the number of head phone mixes your using , that was the old days , I think now if someone wants a custom HP mix if you can provide grouped sends of drums or keys to stereo channels and mono feeds of the rest out to small personal HP mixers ,they performer can easily and intuitivly set up their own Hp mix ,with their own phones if they like ,and you never have to your attention divided between monitor and recording path again . A small 10 or 12 channel rotary fader mixer does the job nicely ,the performer can also eq the channels to their own taste ,where when a Hp feed is shared ,it can be impossible to please everyone . Most musicians are happy to share a monitor mix in the control room Ive found , on the big monitors . Electronic sounds like bass and Keys I generally find better to do in the control room ,less too-ing and fro-ing ,better communication and quicker ,mostly.

A seperate issue ,yet linked is what drives the HP system ,all too often Ive found ,poor phones driven by poor amplifiers ,at moderate volume these might just about work ,If you have a very loud guitarist who wants to crank his marshall stack upto full and stand in front of it ,while overdubbing with headphones on ,the average HP output stage is going to be nowhere near adequate , much much better is using a common integrated hifi amp as source ,you can drive as many pairs of phones as you want ,and clipping wont ever be an issue .It became manditory at some point for broadcast stations who often used a power amp for HP drive to fit limiters to the headphones .

Theres a nice feature on my Amek Bc3 , its where the pan on all channels and returns can function in one of two ways ,a flip switch changes pan to image control  and now you can have either L-R at one extreme, mono centre in the middle or R-L , its a nice thing as sometimes stereo channels seem to sound better reverse panned , its also great for mixing back in effects in stereo .

On the subject of mixing back in effects out of phase , yep theres good stuff to be found there  , I run a couple of boss choruses into  mixer line ins ,by half patching the unballanced cable into the balanced line in jack you get instant phase reversal , theres one setting where most of the effect cancels from the two pedals , but you still get a kind of fairy dust on your sound , its subtle harmonically related content ,if your soundscape is wide open and spacious it thickens up voice in particular very well ,keys or acoustic instruments too , its seems to take a  mono 'in the middle' sound source and give it a great stereo spread , your still only feeding the pedals mono in any case ,whats more important is how you handle the stereo returns  . Each of the buss and master modules on my mixer has its own stereo return ,but it could be equally easy to add a dedicated strip of line ins to your mixer ,with rotary fader ,pan /image control and  switch  , mute , pfl

So it seems  like the some might regard stuff as out of date this that or the other  , I wonder what the modern studio is like ,Id say the client expects to be able to do their own HP mix on the ipad or tablet , probably technically possible ,but what a load of feckin' BS  ;D

 
Thanks everyone for more input on this subject!

Or it could be a dedicated talkback system in you monitor controller.
A separate issue, yet linked is what drives the HP system. All too often I've found poor phones [drive] poor amplifiers
I scooped a Grace m905 last year that has stereo cue I/O with a nice headphone amp. The talkback sums to cue when pressed so I'll be using it in the console.  I've contacted their tech department as I'd like a way to automatically switch monitoring inputs when selecting PFL from the aux bus on the console. I've yet to hear back about it.

Also your Cue system ( headphone mix) could be a pile on type switch.  This allows the main control room mix to feed cues for a quick mix to performers
Quickly being able to change the HP/monitor mix to the performers is great thing
Are you guys are talking about a dedicated cue bus that can receive program and/or a few external inputs (iPhone etc)?
Adding a 'cue' button on one of the Aux bus sends could move it over, and of course increasing volume on a particular channel aux could raise that part in the cue's mix.

Hmm... Switching pgm in and out of the cue mix for performers would mean attenuation compensation would be necessary. Sounds complicated (for me).

Edit: I think the way the 1608 tackled this problem was to add a switch on all channels for aux 7&8, which sends them directly to a  subgroup as they have no explicit 'cue' features I believe. There's also pgm and mix insertion on each aux return bus.

One more thing: I can see the value in multing DAW outs to a separate (cheap) mixer that goes to HP's in the recording room. This would negate the need for cue 'features' in the desk. It would give the performer(s) a sense of control as well. It would also free up auxs. Something to ponder...
 
In biggish mixers you would typically have three (stereo) outputs. The masters which go to your stereo recording device; the monitors which go to the speakers in the control room and studio that fees speakers/phones in the recording area.

Like the monitors, the studio feed would often have an input selector. It would typically be switchable to a couple of aux sends (for foldback) or to the masters (for playback) and sometimes a spare unassigned input. Talk back to artistes could be accomplished in one of two ways - either by a feed onto the relevant aux send buses or more likely via a relay that directly interrupts the feed from the above mentioned selector.

Cheers

Ian
 
Ian mentioned solo is not necessary,
But PFL is a must.

Edit: Trying to wrap my mind around this one.  We are talking about the aux bus solo correct?  Not channel aux pfl. Channel aux pfl is clearly essential. I'm trying to figure out how to solo the aux bus and have it retain the channel signals.

Quite a disadvantage not having a lot of time in front of physical mixers. I might have to visit a local studio and get some hands on.
 
OK, I have been giving this some more thought because I have just been laying out some aux return front panels. First thing is to say that all channels are basically:

Mic pre ==> EQ ==> Fader ==> Routing

where the routing also has a connection to pre the fader.

Next you need some way to set up gain staging and check audio quality of a channel. Solo and/or PFL is the normal way to do this. PFL is easiest so I cover that first. PFL switch routes a pre-fader signal to the PFL bus and a dc signal to the dc PFL bus. THe output of the PFL bus amp feeds the monitor section where a relay, operated by the PFL dc, switches the studio monitions away from whatever the are selected to, to the PFL bus. Hence PFL does not affect the main mix so it is safe to operate anytime during a session. It only affects what is fed to the monitors. Rarely if ever do you press more than one PFL button at a time., The downside of solo PFL is that it is pre-fader so it is great for checking gain staging but no good for checking individual levels in a mix.

That is where Solo comes in. There are two  basic types of solo. Destructive and non-destructive. The non-destructive version is much like PFL except it is taken after the fader, usually from the pan pot. So in this case  the Solo button feeds a stereo bus and a dc bus and is connected to the monitors exactly the same as PFL. So you get to hear the channel exactly as it is being fed to the main L/R buses but, like PFL ir does not affect the mix.

The destructive kind of solo just uses a dc bus. When the Solo button is pressed, the dc bus mutes all channels except the Solo'd one. As long as you are monitoring the master L/R bus you hear the one channel exactly as is is being fed to the mix, just like the non-destructive version, except the mix itself has been destroyed.

So, what about aux returns? If they have PFL, all that happens is the monitors get fed the aux return so you hear the FX and can check its level and quality. Same with non-destructive Solo except get to hear the level of the return in the mix and its pan position. These two work because they have their own buses and do not affect the main mix. Destructive mix is the problem child because it mutes all channels except the one Solo'd . Usually, muting a channel also mutes its aux sends so the FX gets no signal so the return is just silence - not much use. However, there is nothing to stop you (destructively)  soloing a channel and the aux return for its FX together because they will simply be mixed to the master bus. So you can get an idea of how they sound together but there is no way to check levels of the return.

So, what does this mean for the aux return module? PFL is essential for level setting as it is with a regular channel. Neither type of Solo does much for you unless you want to hear a channel plus its FX. The only advantage of destructive solo is it is cheaper to implement.

Aux returns obviously do not need a mic pre and generally do not need a full blown channel EQ. So, referring to the original signal flow above, they need little more than a fader and some routing. Aux returns will almost always come from post fader FX so you don't really need any post fader aux sends in an aux return module. Also you probably do not need a slider fader. So what I have chosen to do is make the aux return module almost identical to a channel routing module. The differences are the post-fader aux send control(s) are removed and replaced with a rotary level control (and perhaps a simple HPF). Pre-fade aux sends remain (to send reverb to artistes) and the pan pot, pfl and solo switches are retained.

To put this into context, my current mixer design layout goes, from top to bottom, channel modules, routing module and lastly fader. For the master section I populate it with master module, aux return module and master fader. The aux return module has pre fade aux sends, pan and solo/pfl in exactly the same positions as the channel routing modules.

Cheers

Ian
 
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