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Q&A March 2002

Your Technical Questions Answered
By Various

Q&A

Q. Can you tell me something about a vintage mic I've found?

I've tried posting this question in the SOS forum, but can well imagine that it's beyond the expertise of most forumees, and I've had no response.

Recently, I was all set to get myself a second-hand AKG C1000, but then I discovered an old Lustraphone mic at my Mum's house, and was wondering if it'll do the job. It's at least 40 years old, and was apparently used at the BBC. There are no serial numbers on the mic itself — just a beautiful badge in the middle: 'High Impedance, Lustraphone, Made In England'. On the underside of the base there are two sets of serial numbers: DC159 and B3167.

Has microphone technology moved on so far as to render this gorgeous-looking old beast obsolete, or can a high-end mic from yesteryear still cut it? I'd plug it in and have a listen, except that my mum's house is in London, where I'm staying at the moment, and my studio is in Amsterdam.

Jim

Technical Editor Hugh Robjohns responds: I'm afraid I have never come across the Lustraphone name before. However, I have done a bit of digging around and I'm indebted to Angus McKenzie for his assistance.

Lustraphone was a contemporary of Grampian and Reslo from the 1950s — all British microphone manufacturers building ribbon and moving-coil mics mainly for the amateur, semi-pro and PA industries.

The mic I suspect you have is probably an omnidirectional moving-coil design dating from the late 1950s and was very popular for wildlife recording, often used in conjunction with a parabolic dish also manufactured by Lustraphone. This mic was also sometimes used as a lavalier (with a suspension string running around the neck of the user for hands-free operation), or hand-held for radio news-gathering and interviews on location — hence the possible BBC application.

However, I have been unable to identify the specific model numbers you supplied (DC159 is probably the model and B3167 the serial number). The only model numbers I have found references for are ribbon designs with model numbers VR53 and VR64 and the Sterolus VR/65NS dual-head ribbon, a single-bodied coincident stereo mic.

Apparently the designer was an Austrian named George Pontzen. Looking through old Hi-Fi Yearbooks, I see that Lustraphone Ltd is listed with an address in North London. However, I believe the company was in some financial difficulties in the early 1970s and, despite introducing an interesting audio amplifier to expand its product base, it closed a few years later.

As far as using the mic is concerned, there should be no real problem, although I doubt it will perform as well as the second-hand AKG you were considering. If you hold the unit up to the light, you may be able to work out whether it is a moving-coil or ribbon design. If it turns out to be a ribbon, you will probably need a lot of gain. Also make sure any phantom-power supply from your preamp is turned off — as the mic is marked high-impedance, it may well also be unbalanced. Check the wiring carefully before connecting.

Q. Why don't my synths' sounds work well together in a mix?

Q&AI have been dabbling with music composition for a number of years now and have been slowly building up my own home recording setup, based around a Novation Supernova, an Access Virus and a Roland XV3080 as my main sound sources. However, as my compositions become increasingly ambitious, I am realising how much of a beginner I am in terms of recording and mixing.

Q&AAlthough each of my instruments is capable of producing rich and inspiring stereo textures that sound totally impressive on their own, I find that when I try and combine them to produce a multitrack composition, I have immense difficulty in producing a satisfying mix. There seems to be just too much reverb and stereo 'width' in each sound when they are combined together.

Q&ASo I find myself editing the sounds, removing all effects, sometimes recording them in mono rather than stereo, and only applying effects at the mixdown stage. But is this what I should really be doing? After all, these instruments have such impressive built-in effects and stereo treatments that I'm sure I must be doing something wrong in completely bypassing them! I am wondering if there is a general rule of thumb when it comes to recording electronic instruments with stereo outputs and built-in effects. Any advice you can give me would be very much appreciated!

Tim Shoebridge

Editor Paul White responds: Yours is a common problem, because most synth presets are designed to sound big and impressive in the shop. If you want to layer multiple sounds, it's often necessary to simplify them, much as you are doing, so it seems that you have a greater appreciation of the production and mixing process than you give yourself credit for.

It helps enormously to listen carefully to commercial records, to see what kind of sounds they are using. Often you'll find that there are relatively few parts playing at the same time, and where several parts are needed, the sounds are tailored accordingly. For example, in a dance track, you can afford to use quite a lot of short, percussive blips and ticks, but you wouldn't want to layer the same number of chordal pad parts, or you'd just end up with a dense mess.

Q. How do contact microphones work?

I'm doing a project which includes using contact microphones. I'm using a C-ducer 3-inch strip. I know that this is a capacitive transducer, but could you tell me how it actually works?

Ros Britt

Technical Editor Hugh Robjohns responds: The C-ducer (and other contact mics of the same type) are generally piezo-electric devices — the 'capacitive' tag is really a misnomer. Piezo-electric elements are little used in modern recording practice, except in very specialised areas where their characteristics are particularly well suited — sonar hydrophones, mechanical positioning devices, and for very high-level acoustic noise measurements, for example. When arranged in the form of a tape or foil (as in the C-ducer), piezo elements are also commonly used as 'contact' microphones, usually for recording stringed instruments (bowed, plucked or strummed), pianos, and most percussion.

A piezo-electric element is a crystalline material with the specific property of developing a voltage across its opposite surfaces when flexed or deformed slightly (and vice versa — piezo loudspeakers exist too). Suitable crystals include potassium sodium tartrate (Rochelle Salts), ammonium dihydrogen phosphate (ADP), and lithium sulphite. These crystal structures are often arranged with two substrates cemented back-to-back in opposite 'polarities', to provide a bipolar voltage output — a configuration called a 'bimorph piezo element'.

The piezo element has a very high impedance and therefore requires a battery or phantom-power supply (depending on the model) to power an internal impedance-conversion circuit, possibly with a degree of amplification too. In general, the higher the powering voltage, the greater the output level and headroom will be.

Using this kind of contact mic is as simple as fixing the appropriate side of the microphone tape or foil in direct contact with the vibrations of a sound source, usually with double-sided adhesive tape. (Both permanent and non-permanent tapes are generally provided with new contact mics. Make sure you use the right type of tape for the application, or you'll have a very grumpy musician to deal with!) Of course, the difficulty is in deciding where to fix the contact mic, as every instrument vibrates and resonates differently, and the amplitude, frequency balance and performance noises vary considerably with position.

The main advantage of a contact mic is that the mechanical nature of the sound pickup makes it relatively impervious to airborne vibrations — acoustic sound — and it is therefore largely immune to feedback and howl-rounds in live-sound applications, or from unwanted spill in recording studios. However, the bad news is that the sound quality is often rather unnatural, even mechanical. Performance noises — fingers on strings, bowing variations, damper-pedal squeaks and so on — are often very prominent too. Like any microphone technique, the advantages and disadvantages of using a contact mic have to be carefully weighed for specific applications.

C-ducer, probably the best-known manufacturer of contact mics of this type, offer three distinct product lines, with foils of varying lengths to suit different instruments and applications, and with different designs of impedance converter and powering regime. More information can be found at www.c-ducer.com, where you can also obtain a simple positioning guide for a variety of instruments.

Q. Is there a combined soft sampler and sequencer on the market?

I'd like to buy a combined soft-sampler and sequencer for my PC, but I'm not sure which of the software packages out there contain both of these. I notice, for example, that in your Terratec EWX24/96 soundcard review (April 2001), you state that the bundled sampler and sequencer won't work concurrently. Is there a single application that does both?

Also, I'm not sure if I need a new soundcard. I have an Athlon 1.2GHz office PC with no music software on it at present. It has a basic SIS 7018 soundcard with just a mic input. I'd like to sample directly into the PC, and also import/export WAV files from/to my Akai DPS16. My priority is sample editing: stretching, reversing, slowing down, adding effects, and so on. I only need basic sequencing (eight tracks is plenty). Some of the cards with bundled software look very good value compared to 'software-only' prices. Also, if any card or software offers a massive sound library bundle, then I'm prepared to pay more than the Terratec, for example.

Frank Foley

Assistant Editor Sam Inglis replies: I don't know of any soft samplers that are also sequencers, but there are a couple of possible solutions. One is to use a soft sampler that works as a plug-in within a sequencer. The obvious choices are Emagic's EXS24 sampler running within Logic Audio, and Steinberg's HALion running within Cubase. Both are currently on special offer as bundled deals. There are also shareware soft samplers, such as V-Sampler, which also works as a plug-in within compatible applications. Another option would be to buy a soundcard that has sampling built in: for instance, Creative Labs' Soundblaster range supports SoundFonts, which is a kind of sample format. There are also more professional sampling cards from the likes of Creamware.

Depending on how you want to work, you could also check out Sonic Foundry's Acid, or programs such as Making Waves. These are not traditional samplers, but sequencers that work with short segments of audio, allowing you to do time-stretching and pitch-shifting in real time to get them to fit your song.

I would say you certainly need to get a new soundcard. The mic input on the SIS card is likely to be horrendously noisy, and won't allow you to record stereo samples. It might even be a half-duplex card, meaning that you can't record and play back at the same time.

Q. Which soundcard should I upgrade to?

I have for several years used a Yamaha SW1000 card in my PC, which is excellent. However, I also have a Soundblaster Platinum Live!, which can cause conflicts with the SW1000 drivers. These tend to manifest themselves in strange ways, such as crashes on saving MIDI files, or being unable to load samples into the arrange page. The solution is simple: you disable the Soundblaster in System Properties and reboot, or run a dual boot where the Soundblaster is disabled. Fine, but the SW1000 does not have a CD audio connection, so if you wish to load audio sample CDs, or simply play audio CDs for comparison, you cannot do this without complicated re-configuring, or copying them all to your hard disk, wasting disk space.

I am thus thinking of upgrading my soundcard to an eight-in/eight-out, 24-bit/96kHz system, as I am recording more real bands, and I have grown out of the sounds of the Yamaha card. I also want to take advantage of the new crop of 24-bit A-D converters, and have been looking at various cards, such as the Aardvark Q10, the M-Audio Delta 1010, and the Edirol 2496. Is there a one-card solution to my situation, or are there any cards that will happily sit alongside any of the above?

David Walton

Q&APC specialist Martin Walker replies: To be honest, most CD-ROM drives provide distinctly average audio playback quality through their budget built-in D-A converters, and even if you have one of the few featuring a digital audio output, very few soundcards have a suitable digital input. This is because, once connected, you would have to slave your soundcard to the clock signal derived from your CD-ROM's digital output to avoid clicks and pops — not a recipe for the best audio quality, since you can't expect a particularly low-jitter clock signal from such a cheap item. So, every time you wanted to listen to CD audio, you'd have to switch to external clock using your soundcard utility software, then back to Internal for higher audio quality when recording or playing back audio files.

The reason you don't have this extra hassle with the SB Live! is that it uses Asynchronous Sample Rate Conversion (ASRC), such that every digital signal is re-clocked to 48kHz on the way in, because the internal engine of the 10K1 chip is fixed at this sample rate. This is certainly handy, but the conversion does degrade the signal slightly.

Very few other soundcards have a CD digital input (although Terratec's EWX24/96 is one that comes to mind), so even if you buy a more upmarket eight-in/eight-out model you'll still have to find a solution for listening to CD audio. On my previous PC I soldered up audio leads that terminated on its back panel in standard quarter-inch jack sockets, and then patched these into my analogue mixer — handy, but still lo-fi.

However, as much software, including Nero, Wavelab, recent versions of the Windows Media Player, and even some shareware, includes real-time 'ripping' features, there's no need for this. As long as your CD-ROM drive can digitally extract audio at 1x speed or faster, the software can grab a digital clone of the data and play it back through your soundcard in real time. My Yamaha 24x CD-R/W drive extracts audio at about 11x. The audio data isn't then heard via the CD-ROM D-A converters, or via its digital output, but gets passed directly over the computer's PCI buss, and then through the D-A converters of the soundcard, using its high-quality internal clock for the ultimate audio quality.

If you want a more expensive soundcard, I'd remove the SB Live! but leave the SW1000XG for its MIDI synth capabilities — it's roughly equivalent to a Yamaha MU90 synth anyway, and if you still want to upgrade its sound quality you could perhaps invest in a Kenton Plugstation (reviewed in SOS August 2001), which would give it 24-bit converters and the ability to add up to four PLG cards. I've never had to remove mine for a soundcard review, and it has happily run alongside several dozen review models to date.

The eight-in/eight-out soundcards you mention are all suitable, but you might also consider Echo's Layla 24, the EgoSys WaMi Rack24, and Terratec's EWS88MT. However, if you are recording real bands, the built-in mic preamps of Aardvark's Q10 may avoid the need for an external mixing console or rackmount preamps. If, on the other hand, you already have these, you could buy an eight-in/eight-out soundcard with line-only inputs, and save some money.

Published March 2002