Q. Can I output my final mix one channel at a time?

Sound Advice : Mixing
 
I have recently purchased a Golden Age Project Pre 73 MkII and Comp 54 on the recommendation of someone from the SOS forums, and I am so pleased. I use an RME Babyface and wondered, with my limited hardware, would it be possible to output my final mix one channel at a time through the Comp 54? The reason I ask is that the hardware adds something that no VST seems to be able to do. If someone knows how I could do this it would be great. If it matters, the DAW I am using is Reaper.




Via SOS web site



SOS Technical Editor Hugh Robjohns replies: The answer is yes, but it's not as straightforward as it might appear and you need to be careful.



The basic problem is that when you're working with a stereo mix the stereo imaging is determined by the subtle level differences of individual instruments in the two channels. A compressor exists to alter the level of whatever you pass through it dynamically, depending on its own level.



Imagine an extreme situation where you have some gentle acoustic guitar in the centre of your mix image, and some occasional heavy percussion panned hard left. If you process those two channels with separate unlinked compressors, the right channel compressor only sees a gentle guitar and does nothing, while the left channel compressor will feel obliged to wind the level back every time the mad drummer breaks out. While you may like the effect a certain piece of gear (like this Golden Age Project Comp 54) has on your recordings, passing your left and right channels through it separately is not a good idea. The reason for this is that the compressor can only react to what it is fed at any given time. So when the left and right channels are heard together — after being run through the Comp 54 — the sound will be very uneven. You can get around this by setting up an external side-chain input, which will cause the compressor to react to what it gets from the other channel, but with the Comp 54 this is not possible, so another approach altogether might be in order.While you may like the effect a certain piece of gear (like this Golden Age Project Comp 54) has on your recordings, passing your left and right channels through it separately is not a good idea. The reason for this is that the compressor can only react to what it is fed at any given time. So when the left and right channels are heard together — after being run through the Comp 54 — the sound will be very uneven. You can get around this by setting up an external side-chain input, which will cause the compressor to react to what it gets from the other channel, but with the Comp 54 this is not possible, so another approach altogether might be in order.



Listen to the two compressed channels afterwards in stereo and the result will be a very unsettled guitarist who shuffles rapidly over to the right every time the percussionist breaks out (probably a wise thing to do in the real world, of course, but not very helpful for our stereo mix).



If you process your stereo mix one channel at a time through your single outboard compressor, that's exactly what will happen. The compressor will only react to whatever it sees in its own channel during in each pass, and when you marry the two compressed recordings together again you will find you have an unstable stereo image. The audibility of this, and how objectionable you find it, will depend on the specific material (the imaging and dynamics of your mix), but the problem will definitely be there.



Stereo compressors avoid this problem by linking the side chains of the two channels, so that whenever one channel decides it has to reduce the gain, the other does too, and by the same amount. In that way it maintains the correct level balance between the two channels and so avoids any stereo image shifts.



You can achieve the same end result if your single outboard compressor has an external side-chain input, but sadly I don't think the Golden Age Project model does. If it did, what you'd need to do is create a mono version of the stereo mix in your DAW and feed that mono track out to the compressor's external side-chain input, along with one of the individual stereo mix channels (followed by the other). That way, the compressor will be controlled only by the complete mono mix when processing the separate left and right mix channels, so it will always react in the same way, regardless of what is happening on an individual channel, and there won't be any image shifting.



That's no help to you with this setup, of course, but don't give up yet, as there is another possibility. You could take an entirely different approach, and that's to compress the mix in a Mid/Side format instead of left-right. It involves a bit more work, obviously, as you'll need to convert your stereo track from left-right to Mid/Side, then pass each of the new Mid and Side channels separately through the compressor, and then convert the resulting compressed Mid/Side channels back into left-right stereo. Using an M/S plug-in makes the task a lot easier than fiddling around with mixer routing and grouping, and there are several good free ones around.



The advantage of this Mid/Side technique is that, although the Mid and Side signals are being processed separately and independently, the resulting image shifts will be much less obvious. The reason for this is that instead of blatant left-right shifts, they will now be variations in overall image width instead, and that is very much less noticeable to the average listener.



Sorry for the long-winded answer, but I hope that has pointed you in the right direction.



SOS Reviews Editor Matt Houghton adds: I agree with Hugh's suggestion of M/S compression. I regularly use that when I want to deploy two otherwise unlinkable mono compressors, and there's no reason why you can't process the Mid and Side components one at a time. The only issue here will be your inability to preview what you're doing to a stereo source, so be careful not to overwrite your original audio files! However, I sense that it's the effect of running through the compressor's transformers that you're hoping to achieve. In that case, just set to unity gain and set the threshold so that the unit isn't compressing, and then run the signal through it. If it is standard L/R compression you want, you could always get another Comp 54, as although they're mono processors they're stereo-linkable with a single jack cable.



In Cubase, I find that the best approach to incorporating such outboard devices into my setup is to create an External FX plug-in for each device, and then insert that on each channel and print the result. In Reaper, the equivalent tool is the excellent ReaInsert plug-in. This approach not only makes the process less labour intensive in the long run, but means that you can drag and drop the processor to different points in the channel's signal chain, should you want to.  

Published in SOS February 2012

Queen's Keyboard Player Spike Edney - Behind the scenes with the Korg Kronos

Q. Is asymmetry in monitors a problem?

I'm considering AVI's Pro Nine Plus system for my main nearfield monitoring, partly based on the great review they got from Paul White back in September 2005 (/sos/sep05/articles/avipronine.htm). Should I be worried about the fact that the tweeter mounting and porting are both asymmetrical in relation to the main driver? Will this cause slight delay/phasing issues when placed in the classic equilateral-triangle stereo setup?




AVI's Pro Nine Plus monitors (left) have their tweeter mounting and porting asymmetrical to the main driver. This is actually relatively common, as you can see from the Acoustic Energy AE22s and the Dynaudio BM15As (below).AVI's Pro Nine Plus monitors (left) have their tweeter mounting and porting asymmetrical to the main driver. This is actually relatively common, as you can see from the Acoustic Energy AE22s and the Dynaudio BM15As (below).Q. Is asymmetry in monitors a problem?Q. Is asymmetry in monitors a problem?



Via SOS web site



SOS contributor Mike Senior replies: Opinions differ about a lot of aspects of speaker design, as you can easily see even just from comparing the external appearance of a selection of similarly priced monitors. One such moot point is how important symmetrical driver placement is, and the Pro Nines are by no means the only speakers that have their tweeters skewed to one side like this. The Acoutic Energy AE22s and Dynaudio BM15As both feature this kind of setup, and are both nonetheless well-regarded. Although I've not tried these specific speakers myself, the main thing I'd be wary of in principle is that the size of the stereo sweet spot may be reduced. No matter which way you move your head (forward/back, side to side, or up/down) the potential for inter-driver phasing in the mid-range appears to me to be greater than with a more traditional vertically stacked driver configuration. Even if this theoretical concern is borne out in practice, though, the real question is how much it'll matter to you. If you're happy to stay in the sweet spot most of the time, and can check the mid-range balance with a single-driver speaker such as an Auratone (or similar), then it may not be a huge practical concern. Personally, I'd say that if you like the speakers otherwise, don't let the asymmetry be a deal-breaker.



As for the ports, again I don't think their asymmetry should really put you off, and although I find that porting in budget-level monitors can cause all sorts of low-end monitoring problems, I would imagine that these speakers are probably getting into the kind of price range where the potential problematic side-effects of the porting are kept well enough under control that you can work with them for mixing purposes. Certainly, the 90Hz low-end boundary on the published frequency-response figure leads me to suspect that the port hasn't been overhyped, as it seems to be on many budget models, and that counts for a lot in terms of accuracy.  

Published in SOS February 2012

Korg Krome Music Workstation -- Official Product Introduction Video

Q. Is flutter echo a problem in a well-treated room?

Sound Advice : Recording




My daughter managed to play a tough piece she's been practising on the keyboard this weekend. She played it so well that we clapped our hands... then we noticed how strange the clapping sounded. It rang on but died very quickly, and for the time it rang on, it sounded very metallic and almost robotic.That was close to the middle of the room. The room is partially treated at the moment, with panels at the side-wall reflection points and ceiling, one on the ceiling, and three corner superchunks. I tried clapping again with some further panels on the side walls directly to the left and right of where I was sitting, and the noise disappeared. I understand enough to realise the sound is the clap bouncing back and forth between the two walls, and I'm guessing that this is what folk refer to as flutter echo. What I'm a little less sure about is whether it is a problem, and what — generally — a hand clap should sound like in a well-treated room.



Via SOS web site



SOS Technical Editor Hugh Robjohns replies: If we're talking about the sound in a control room, the point is what the room sounds like when listening to sound from the monitor speakers. It is conceivable that, by design (or coincidence), the acoustics could well sound spot on for sounds from the speakers, but less accurate or flattering for sources elsewhere. And, unless you're planning on recording sources in the control room at the position you were clapping your hands, those flutter echoes might not represent a problem or require 'fixing'.



However, in general, strong flutter echoes are rarely a good thing to have in a control room and I'd certainly be thinking about putting up some absorption or diffusion on those bare walls to prevent such blatant flutter echoes.Flutter echoes in a studio can be distracting and fatiguing, so it's often worth putting up some absorbent foam on bare walls to reduce them. Don't overdo it, though: you need to maintain a balanced acoustic.Flutter echoes in a studio can be distracting and fatiguing, so it's often worth putting up some absorbent foam on bare walls to reduce them. Don't overdo it, though: you need to maintain a balanced acoustic.



You shouldn't go overboard with the room treatment, though, because while working in a control room that has 'ringy' flutter echoes or an ultra-live acoustic can be very distracting and fatiguing, so too is trying to work in a room that sounds nearly as dead as an anechoic chamber!



Of course, traditional control rooms are pretty dead, acoustically speaking, and that is necessary so that you can hear what you are doing in a mix without the room effects dominating things. But the key is to maintain a balanced acoustic character across the entire frequency spectrum. The temptation in your situation might simply be to stick a load of acoustic absorbers on the walls, and that would almost certainly kill the flutter echoes, but in doing so there is also a risk that you'd end up with too much HF and mid-range absorption in the room (relative to the bass-end absorption).



That situation would tend to make the room sound boxy, coloured and unbalanced, and that's why a better alternative, sometimes, is to use diffusion rather than absorption; to scatter the reflections rather than absorb them. The end result is the same, in that the flutter echoes are removed, but the diffusion approach keeps more mid-range and HF sound energy in the room.



The question of which approach to use — diffusion or absorption (or even a bit of both) — depends on how the rest of the room sounds, but from your description I'd say you still had quite a way to go with absorption before you've gone too far.



To sum up, I'd suggest that you're not worrying unnecessarily, and that it would help to put up some treatment to reduce those flutter echoes.    

Published in SOS February 2012

Introducing the MicroKorg XL+: The Micro with More!

Q. How can I make using headphones less fatiguing?

Sound Advice : Mixing



I have been making music for years now, and although I have a set of Genelec 8040s that I use during the day (when I'm home), I have been using a set of Audio-Technica M50 headphones for writing at night, when I usually have the ideas and desire to write, but am unable to, due to neighbours and a sleeping wife.However, lately I have been unable to use the cans, as I've been experiencing discomfort and what I believe is the onset or warning signs of tinnitus. It's been a nightmare trying to adapt to not using cans at night, and I find it almost impossible to get anything other than sequencing done at this low volume!I'm wondering whether there are any miracle headphones or bits of kit that would minimise hearing damage or discomfort while still being (relatively) accurate and enjoyable to use.



Via SOS web site



SOS Technical Editor Hugh Robjohns replies: Firstly, regarding the tinnitus: it's very common, often temporary and may be nothing to worry about. It can be brought on by something as simple as drinking too much coffee or suffering a mild ear infection, but don't ignore or neglect it. Go and see a medical professional and get checked out! If there is a problem, early intervention could make all the difference.

I don't think there are any 'miracle' solutions in headphones. Basically, it comes down to self-control in establishing the most appropriate maximum level for those particular headphones and sticking to it. The simplest solution is to put a mark on the headphone volume control and exercise enough self-discipline to never turn it up past that. If you reach a stage in your mixing when you're finding that maximum level is too quiet, take a break. Give the ears a little time to relax and reset, and then start again.



More volume is not the answer, though. It might seem more exciting and involving, but it doesn't really help to make better mixes — in fact, it usually makes them worse! The reason is that greater volume allows you to hear through a bad mix more easily, and poor balances aren't perceived as such. Working at more moderate levels — the kind of volume that most end listeners will use — encourages a far more critical approach to the mix, as poor balances sound obviously awful! Mixing becomes much harder, certainly, but also much more accurate and with far better end results. This is true of both speakers and headphones.



By all means turn the volume up if you need to check low-level background noises and so on, but do so only briefly. Try to mix at a modest level, and keep that level fixed. If you continually change your monitoring level, your mix will change continually too!



However, the fatigue you're experiencing may involve more than just sheer volume. The M50s are pretty good for the money, but I think you might find it easier to work with a pair of good open-backed headphones that are more revealing. You might find it helpful to read the comments and suggestions for different models in a headphone comparison article we ran in the January 2010 issue (/sos/jan10/articles/studioheadphones.htm). If possible, try different models before buying, to make sure the weight, headband pressure and size of the ear cups suit your head and are comfortable. Open-back headphones do 'leak' more sound than closed headphones, though, and that may be an issue for your wife!



The M50, being a closed-back design, tends to be less revealing of mid-range detail than a good open-backed headphone, and a consequence of this is a natural tendency to keep cranking the level to try to hear further into the mix, but more volume still doesn't quite reveal what you want to hear! Headphones that exert a strong pressure on the sides of the head can also add to the sense of physical fatigue, and the sealed nature of the earpieces quickly makes your ears hot and uncomfortable, which also doesn't help.



I'd recommend trying some good open-back headphones, like the AKG 702s, Sennheiser HD650s or the Beyerdynamic DT880 Pros. They are expensive, but I think you'll find it far easier to mix with them and you'll be much less tempted to wind the level up, although it is still very important to take frequent breaks to allow your perception of volume to reset! Headphones of this calibre provide a top-notch monitoring system that will last for decades if well looked after, and you'll probably hear all sorts of details that your Genelecs don't reveal, too.If you find that your closed-back headphones are quite fatiguing, it may be a good idea to try some open-back headphones, such as these AKG 702s. Decent open-back headphones are often more revealing than closed-back models, and may therefore reduce the temptation to increase the volume.If you find that your closed-back headphones are quite fatiguing, it may be a good idea to try some open-back headphones, such as these AKG 702s. Decent open-back headphones are often more revealing than closed-back models, and may therefore reduce the temptation to increase the volume.Q. How can I make using headphones less fatiguing?



Obviously, though, there is no physical sensation from the low frequencies when using headphones, as there is when using speakers and that can also be a factor in the continual desire to turn the level up, especially if you're producing music that demands strong bass content. The only way around that is self-discipline and learning to trust your headphones.



As a last resort, if you don't think you have the self-discipline to leave the volume control alone, it might be wise to consider investing in a suitably calibrated headphone limiter. Again, it's an expensive option, but I'd suggest that it's well worth it to protect your priceless ears! There's some useful background information here: www.tonywoolf.co.uk/hp-limiters.htm. Also, Canford Audio offer various types of headphone level limiter that can be installed inside headphones or wired into the cable. These are based on a clever BBC design, which is now mandatory within the corporation to ensure that BBC staff don't expose themselves to excessive SPLs through their phones, and it works extremely well. You can read more about it here: www.canford.co.uk/technical/PDFs/EarphoneLimiters.pdf.  

Published in SOS March 2012