Welcome to No Limit Sound Productions

Company Founded
2005
Overview

Our services include Sound Engineering, Audio Post-Production, System Upgrades and Equipment Consulting.
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Our mission is to provide excellent quality and service to our customers. We do customized service.

Monday, August 31, 2015

Q How do I record from my guitar amp’s headphone out?

Sound Advice : Recording



Hugh Robjohns

These are all jack-to-jack cables, but they’re not wired the same. To record from a  headphone output to an audio interface’s input, you’ll usually need the bottom one, often known as a  ‘Y–cord’ or ‘insert cable’.

These are all jack-to-jack cables, but they’re not wired the same. To record from a headphone output to an audio interface’s input, you’ll usually need the bottom one, often known as a ‘Y–cord’ or ‘insert cable’.These are all jack-to-jack cables, but they’re not wired the same. To record from a headphone output to an audio interface’s input, you’ll usually need the bottom one, often known as a ‘Y–cord’ or ‘insert cable’.



I’m seeking some guidance on why I’m unable to record from my guitar amp straight to my audio interface. I’m working with two small amps, a Marshall and a Crate, and trying to record a feed from the guitar amps’ headphone outputs via a Focusrite Scarlett 2i2 interface. Originally, I thought that the headphone jacks on both amps might be broken, but when I plugged in a pair of Sony headphones, the sound came through perfectly clearly. Then I thought the issue might be that the headphone had a quarter–inch TRS connector instead of TS, so I just picked one of those up and tried to hook the amp up to the interface that way. No dice.



I’m not getting total silence, though — if I turn the amp up loud enough I get very crackly audio that sounds like it has a high–pass filter on it. Your guidance would be greatly appreciated!



SOS Forum post



SOS Technical Editor Hugh Robjohns replies: Although headphone amps aren’t technically the best output source for a recording, you should still capture something reasonable if using the correct cables. But the issue here is that the apparently similar quarter–inch sockets in the amp and interface are wired very differently, and therefore carry/expect differently formatted signals.



The headphone output is unbalanced and is wired to be compatible with stereo headphones, even though the guitar amp produces a mono signal. That means that the unbalanced amp output signal is wired to both the tip and ring contacts in the headphone socket, with a common ground on the sleeve. The interface input expects a balanced line–level signal, which means that it only responds to the difference between the signals on the tip and ring contacts.



With a TRS–TRS cable connecting the amp headphone output to the interface balanced line input, the signals on the interface tip and ring contracts are identical; there is no difference, and so there will appear to be no signal. All you’ll hear, as you describe, is the very small error signal resulting from an imperfectly balanced input amplifier, which is usually a very quiet hissy, spitty, toppy sound (see Figure 1).



With a TS–TS (instrument) cable connecting the amp’s headphone output to the interface balanced line input, there is no ring contact, and so the ring output terminal in the headphone socket is shorted directly to ground by the plug sleeve. Inside the amplifier, I suspect the headphone-socket tip and ring contacts are actually wired directly together (rather than having a true stereo output amplifier) since there is only a mono source. This means that the act of inserting a mono TS plug will actually short the entire headphone amp output to ground, leaving no signal to output to the interface at all! (See Figure 2.)



The only workable solution, if you want to record from the headphone output, is to use a ‘Y–cord’, which comprises a TRS plug at the amp end, and two TS plugs for the interface end. It’s often sold as an ‘insert breakout cable’ or a ‘stereo–to–dual–mono output splitter’ cable. When using this kind of breakout cable, the TRS plug provides the headphone socket tip signal on the tip of one TS plug, and the ring signal on the tip of the other TS plug. If you then plug one (or both) of these TS plugs into the balanced line input(s) of your interface, the balanced input circuitry looks for the difference between the signals on the tip and ring again, but this time the TS sleeve shorts the ring signal to ground, and the wanted headphone output signal is applied between the tip and ground, so all is well. (See Figure 3.) Hey presto! It will all work as you want and expect...    


Friday, August 28, 2015

Q How can I export a Pro Tools project for mixing in Reaper?

Sound Advice : Mixing



Matt Houghton

Moving imported WAV files to their time–stamped position in Cockos Reaper.

Moving imported WAV files to their time–stamped position in Cockos Reaper.Moving imported WAV files to their time–stamped position in Cockos Reaper.



My band tracked some songs at a local studio using their Pro Tools rig and I want to mix the tracks at home in Reaper. What’s the best way of getting the session data out of Pro Tools and into my Reaper system?



Dave Matthews via email



SOS Reviews Editor Matt Houghton replies: I feel your pain: we often go through this sort of thing with Mix Rescue projects! The best method really depends on the nature of the project. If it’s just a plain multitrack recording session then it should be a simple case of importing all the audio files to different tracks so that they all start at bar 1, beat 1. You’ll see at a glance which were from the same take as they’ll be the same length. Hopefully, the engineer labelled the tracks/files so you can see which sounds are which.



If you’ve done edits or punch–ins, that adds a layer of complexity, but is still fairly simple. First, ask the studio to ‘consolidate’ all the clips in Pro Tools, to create files that line up as described above. If that’s not an option (or the studio charges you too much for the privilege!) note that Pro Tools automatically time–stamps the WAV files it records and Reaper can read those time stamps. Drag and drop your files into Reaper, select all, right-click on a clip to bring up the context menu, and select Item Processing/Move Items To Source Preferred Position (BWF). All files should line up in the same positions as they were recorded in Pro Tools. Be aware, though, that some DAWs have a default timecode offset (for reasons relating to audio–to–picture applications that you needn’t understand for this task). So you might find, as I once did, that all your files start as if the bar 1 beat 1 position is at +1 hour on Reaper’s timeline. To remedy this, zoom right out to find the files, select all, and drag all files to your preferred starting point



If the Pro Tools session includes more information, such as pan settings, clip gain, volume automation and so on, you’ll need either to bite the bullet and redo all that work yourself, or use another method to transfer the files. Some of that information can be transferred as OMF/AAF files, but (a) I’ve found that these are unreliable and inconsistently implemented by different DAWs and (b) Reaper doesn’t support them! The best bet in this situation is to invest in Suite Spot Studios’ AA Translator software, which reads and writes more project data in a wider range of formats than any other software I know of. I have a copy here under review and have been most impressed so far. It’s Windows only, but with the manufacturer’s help I have it running in Winebottler on Mac OS 10.9.5.



The trickiest thing is transferring plug-in effect or instrument data from one DAW to another. Your best bet is to print those effects as audio. But you should also be able to get the studio to supply the MIDI data from the session to enable you to rebuild any instrument parts.    

Tuesday, August 25, 2015

Q. Does changing the phase of drums make a big difference?

Sound Advice : Recording




Mike Senior

Although polarity/phase adjustments at mixdown can radically affect the sound of a multimiked drum kit, they might make very little difference at all. The only way to find out is to check...

Although polarity/phase adjustments at mixdown can radically affect the sound of a multimiked drum kit, they might make very little difference at all. The only way to find out is to check...Although polarity/phase adjustments at mixdown can radically affect the sound of a multimiked drum kit, they might make very little difference at all. The only way to find out is to check...



I’ve recently become interested in manipulating phase while mixing recorded drums to see what that would do, as I’ve not messed with that before! The drums in question were recorded onto seven channels with three non-matching mics: front, back and overhead, plus kick, snare and two tom mics. I downloaded the Sonalksis FreeG fader, which has a polarity reverse button, and also the UAD Little Labs IBP variable phase-manipulation plug-in. I tried about every variation I could come up with in terms of phase with the seven channels, starting with polarity flips and then slowly sweeping the 180-degree range with IBP. While there was some variation in sound as a result, it was minimal, and not necessarily better — just different. Certainly not dramatic and nothing that I ended up using. Is that unusual?



Tom Dyer, via email



SOS contributor Mike Senior replies: Not at all. Depending on the mic positions, spill levels, and balance between the drum mics (and whether they were gated during recording), phase can make anything from a massive to a miniscule difference. However, it’s very rare that it makes no discernible difference at all, so it’s always worth checking for the most appealing-sounding combination as a matter of course whenever you’re dealing with multi-miked recordings. Yes, the polarity/phase relationship you choose will be a subjective decision, but then subjective preferences are a lot of what mixing is about, after all!



I’d also add that a final mix is rarely constructed from a handful of huge ‘night and day’ sonic changes, but is almost always the result of hundreds of subtle little tweaks, so even when the effects of a single polarity/phase adjustment are fairly minimal, the cumulative effect of a such adjustments across multiple tracks may nonetheless add up to something more substantial.