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, October 20, 2014

Q. What settings should I use when backing up vinyl?

Hugh Robjohns

I've just started putting my vinyl collection onto my hard drive for the purposes of backing up and preserving it. I'm currently using Audacity to record the WAVs but I don't know what settings I should be using. Someone mentioned that I should record at 32-bit — is this correct?




Via SOS web site

As the longest word length any converter can record in is 24 bits, that's the setting you should use when backing up your vinyl. If you're likely to want to run de-clicking software, it's worth making your original recordings at 96kHz.

SOS Technical Editor Hugh Robjohns replies: To answer the last question first: not really! The longest word length you can get from any converter or interface is 24 bits, so that's the format you should record and archive your files in, and if you plan to make 'safety copies' in the CD audio format you'll need 16/44.1kHz files.



However, the 32‑bit format does exist. Most DAWs process signals internally using a '32‑bit floating-point' format and some allow you to choose whether to save ongoing projects in this native form to avoid multiple format changes as a project proceeds. In general, the 32‑bit floating‑point format still works with 24‑bit audio samples, but adds a scaling factor using the other eight bits to allow it to accommodate very loud or very quiet signals following processing. The problem is that not all DAWs share the same 32‑bit float format, so, for maximum compatibility, it's not the best idea to long‑term archive audio files in this format.As the longest word length any converter can record in is 24 bits, that's the setting you should use when backing up your vinyl. If you're likely to want to run de-clicking software, it's worth making your original recordings at 96kHz.As the longest word length any converter can record in is 24 bits, that's the setting you should use when backing up your vinyl. If you're likely to want to run de-clicking software, it's worth making your original recordings at 96kHz.If your records are in bad shape, it might be worth using de‑clicking software on your recordings before doing anything else.If your records are in bad shape, it might be worth using de‑clicking software on your recordings before doing anything else.

If your records are in bad shape, it might be worth using de‑clicking software on your recordings before doing anything else.

As for the other settings, it depends on the condition of the records you are transferring and how much processing you are planning to do to them. For starters, though, if your records suffer from clicks, these can have a huge dynamic range that can easily overload the A‑D converter (which doesn't sound nice!). The sensible way around this is to leave masses of headroom when digitising, and that means using a 24‑bit analogue-to-digital converter and leaving at least 20‑30dB of headroom — more if the noise floor of the disc and converter allow it.



If you are planning to run de‑click software, then I would also recommend using a higher sample rate during the digitisation. That makes things much easier for the software, so digitising at 24/96 would be a good starting point.



If you are going to use de‑clicking software, run that first. There are various packages that do this, from the superb (but expensive) CEDAR tools, down to various low‑cost plug‑ins. I often use Izotope RX, which is a very cost‑effective solution. Alternatively, you can manually edit out the clicks or, in some DAWs, redraw the waveform to erase them.



With the clicks taken out, you can then remove the (now empty) headroom margin by bringing up the level of the music signal to peak close to 0dBFS (I generally aim to normalise to ‑1dBFS).



You may, at this stage, want to deal with the surface noise — again, there are various tools for that — or adjust the overall tonal balance, but my advice would be to tread lightly if you do go down these routes.



Finally, sample‑rate convert the files down to 44.1kHz, reduce the word length (with dither) to 16 bits, and burn to CD.    

 

Korg All Access: Radiophonic Workshop at BBC Maida Vale, with the KingKORG, Kronos and MS-20

Q. Can I use an SM58 as a kick-drum mic?

Sound Advice : Miking

The SM58 is better known as a vocal, guitar and snare mic than anything else — but can it be pressed into service as a kick-drum mic?


Mike Senior



I'll be doing a session with lots of mics and I'm going to be running out of gear choices without hiring, begging or stealing! For the kit, I don't really have all the right mics, so will need to compromise. Is it wise to use a Shure SM58 on kick drum? What can I expect? The SM58 is better known as a vocal, guitar and snare mic than anything else — but can it be pressed into service as a kick-drum mic?The SM58 is better known as a vocal, guitar and snare mic than anything else — but can it be pressed into service as a kick-drum mic?If you have to use a kick‑drum close‑mic that lacks low end, the neatest mix fix is usually to employ some kind of sample‑triggering plug‑in to supplement the sound, such as Wavemachine Labs' Drumagog, SPL's DrumXchanger or Slate Digital's Trigger.If you have to use a kick‑drum close‑mic that lacks low end, the neatest mix fix is usually to employ some kind of sample‑triggering plug‑in to supplement the sound, such as Wavemachine Labs' Drumagog, SPL's DrumXchanger or Slate Digital's Trigger.Q. Can I use an SM58 as a kick-drum mic?Q. Can I use an SM58 as a kick-drum mic?

If you have to use a kick‑drum close‑mic that lacks low end, the neatest mix fix is usually to employ some kind of sample‑triggering plug‑in to supplement the sound, such as Wavemachine Labs' Drumagog, SPL's DrumXchanger or Slate Digital's Trigger.

Via SOS web site



SOS contributor Mike Senior replies: The first thing to say is that, although this mic (and, indeed, its SM57 cousin) is much better known for vocal, guitar and snare miking, there is also a good deal to recommend it for kick‑drum applications: its physical ruggedness; its ability to deal with high SPLs; and its presence-frequency emphasis, which can, in many situations, help the drum 'click' to cut through the mix, even when it's played back on small speakers. The biggest potential problem will be the low‑frequency response, which has been tailored to compensate for proximity effect in close‑miking situations and so falls off pretty steeply below 100Hz. However, there are several reasons why this needn't actually be a disaster in practice.

Q. Can I use an SM58 as a kick-drum mic?

The first reason is that your microphone placement may well compensate for this, somewhat, especially if you're planning to use the mic inside the casing of the drum, where small changes in positioning can make an enormous difference to the amount of captured low end. It's also worth bearing in mind that lots of low‑end may not actually be very desirable at all, especially if the song you happen to be recording features detailed kick‑drum patterns that could lose definition in the presence of bloated lows. I often find myself filtering out sub‑bass frequencies at mixdown, in fact, as this can make the drum feel a lot tighter, as well as leaving more mix headroom for the bass part.



However, even if you do get an undesirably lightweight kick‑drum close‑mic sound, it's comparatively easy to supplement that at the mix: this is usually one of the simpler mix salvage tasks you're likely to encounter, in fact. One approach is to create some kind of low‑frequency synth tone (typically a sine wave, but it might be something more complex if you need more low‑end support) and then gate that in time with the kick‑drum hits. You can do this in most DAW systems now, using the built‑in dynamics side‑chaining system. I've done this in the past, but I tend to prefer the other common tactic: triggering a sample alongside the live kick‑drum using a sample‑triggering program (see our feature in last month's issue). There are now loads of these on the market, including the examples shown in the screens above.    

Saturday, October 18, 2014

Korg All Access - Matt Sorum Wavedrum Global

Q. My self-build PC isn't working. What tests can I run?

Sound Advice : Maintenance




Martin Walker



I left my recently completed self‑build PC running overnight to run a soak test. During the night it switched itself off, but the next day it came back on by itself, then switched itself off again, and a few hours later it did exactly the same thing. I'm beginning to think that either my new machine is haunted or something in its setup is going wrong. I'd really like to find the culprit!

If you stress-test your CPU using a freeware utility such as OCCT, you can check that it won't overheat and power‑down your machine at an inopportune moment.

Luckily, I've yet to install any software onto the machine — so what tests should I run before I do, to make absolutely sure it's operating correctly and safely?



Via SOS web site



SOS contributor Martin Walker replies: The most obvious culprit for a computer powering down is the CPU overheating and switching itself off to avoid long‑term damage. As for randomly switching back on, this is most likely due to the BIOS settings that determine the devices or specific events that can 'wake up' your computer, which, apart from more obvious things such as pressing the power switch, can also include activity of your mouse or keyboard, another USB or LAN device, or even an alarm function on the motherboard's real‑time clock.



However, you should check for and deal with any basic overheating problems long before you install Windows or any software applications, so here are some quick checks that you can perform within a few seconds of switching on a new PC for the first time. While this always tends to be a nervous moment, you don't need to simply hope for the best.



First, before powering up, check in the motherboard manual for the key press required to enter the BIOS (Basic Input/Output System): this is typically Delete, or one of the Function keys. Then, armed with this information and with the PC side panel off, power up for the first time, pressing this BIOS key every second or so, while simultaneously checking that all cooling fans have started to spin and that the Standby power indicator LED on the motherboard is illuminated.



If any fans fail to spin, or if you smell burning, or even see smoke rising from any component, switch off immediately and double-check all connections. If you hear any sequence of beeps from the motherboard buzzer then, once again, power down. The most likely reasons for this behaviour from the motherboard are a RAM error or CPU overheating (did you properly install the heatsink/cooling fan?).



Otherwise, within a few seconds your PC will finish its POST (Power‑On Self‑Test), checking all the devices connected to the motherboard, and enter the main BIOS screen. This in itself proves that your graphics card is working, that your CPU has been identified, and that at least some of your RAM has been recognised, but this initial screen may also show your connected hard drives and the amount of detected RAM. After you've glanced at these to check everything's OK, navigate to the page labelled 'Health Status' or 'System Monitor' where you should find readouts of all the PSU voltages, along with one or more temperatures.



Check that all the voltages are close to the stated values, and then watch the temperature readings. The motherboard temperature is likely to stabilise quite quickly somewhere in the 30s, while the CPU temperature should rapidly rise to somewhere in the 30‑ to 50‑degrees centigrade range while idling in the BIOS, but not significantly higher. If it does, the CPU fan isn't rotating, due to its either not being plugged in or there being an obstruction. The obstruction could be as simple as a cable preventing it from turning, or you may not have correctly applied a thin layer of heatsink compound. Watch the temperature for a few minutes to make sure it stabilises safely. If it does, it's safe to proceed to other BIOS tweaks and the installing of Windows.



Now when you reach the desktop you know that everything is basically running OK, and can perform more stressful tests to make sure your new PC will cope well under all conditions. Use a utility such as the freeware Prime 95 (www.mersenne.org) or OCCT (www.ocbase.com/perestroika_en) to torture your CPU at 100 percent while monitoring its core temperatures: they will rise, but ideally shouldn't get much above 60 degrees centigrade, and if they rise to over 70 degrees you need to beef up your cooling-fan regime.If you stress-test your CPU using a freeware utility such as OCCT, you can check that it won't overheat and power‑down your machine at an inopportune moment.If you stress-test your CPU using a freeware utility such as OCCT, you can check that it won't overheat and power‑down your machine at an inopportune moment.



Once you're happy that the CPU stays within safe limits, boot your PC from a Memtest86 (www.memtest.org) CD or floppy disk and run it overnight to check that every bit of every byte of your RAM works correctly, so you don't discover a fault the hard way in the middle of a big project. Stay cool!  

Friday, October 17, 2014

Q. How can I remove background noise from a voice recording?

Sound Advice : Recording




Mike Senior



I've made a recording of someone talking, but there's quite a lot of background noise. How can I extract the vocals, or at least bring them out a bit to make them clearer?

The ReaFIR plug‑in within Cockos' freeware ReaPlugs bundle can be used to reduce background noise in a more transparent way than is possible using ordinary expansion or gating processes.

Katy Majewski via email



SOS contributor Mike Senior replies: Assuming that the voice you've recorded is destined to be heard on its own, any kind of normal full‑band dynamics process, such as the expansion or gating you might use at mixdown, will almost certainly be too blunt a tool for the job. All they'll do is restrict the noise only to those moments when the voice is actually speaking, which won't help make the voice itself come through any clearer.



In the first instance, I'd therefore recommend a dedicated multi‑band noise‑suppression algorithm instead: something like the Cockos ReaFIR plug‑in (part of their freeware ReaPlugs bundle) or Voxengo's ReduNoise would be a good first port of call. These work by analysing a section of the recording where the vocal isn't present, in order to build a profile of the noise signal, which can then be used to remove the noise more intelligently. The settings of these plug‑ins can seem a little intimidating, so you'll have to get your manual‑reading cap on, but they're capable of pretty good results in the right circumstances. One tip here, though: when you first try this process, dial up the noise reduction to its most severe so that you get familiar with the strange little digital chirping artifacts it can cause. That way, when you're actually trying to decide on the best compromise between the levels of noise‑reduction and processing artifacts, you'll know what to listen for.The ReaFIR plug‑in within Cockos' freeware ReaPlugs bundle can be used to reduce background noise in a more transparent way than is possible using ordinary expansion or gating processes.The ReaFIR plug‑in within Cockos' freeware ReaPlugs bundle can be used to reduce background noise in a more transparent way than is possible using ordinary expansion or gating processes.



If this doesn't do the job adequately, and the recording in question is an important one for you, it's probably time to call in the professionals, and in this regard I'd personally recommend giving CEDAR Audio (www.cedar‑audio.com) a call. They've been at the forefront of this kind of technology for years, and run a by‑the‑hour restoration service that is comparatively affordable, bearing in mind the cost of the processors they use!    

Korg In The Studio: Freddy DeMarco Demos the Pandora Stomp