What Do I Need?
At a minimum, you will need a computer (I’m using a PC, but it’s relatively similar with a Mac or iOS devices), an audio interface, decent pair of headphones and/or speakers and a guitar cable.
Audio interface is basically an external sound card that converts your input signal from analog to digital, sends it to the computer for processing, takes the processed digital signal and converts it back to analog to be played through the headphones or the speakers. Most interfaces have some sort of an analog preamp that will affect the sound before it gets converted to digital signal. Sound quality of our recordings will depend primarily on the quality of the preamp as well the quality of the DAC (Digital-to-Analog Converter). Naturally, more expensive interfaces will have better quality DAC and preamps.
Unlike analog effects and amplifiers, digital modeling does not process input signal in real time, meaning that there is a latency between input signal getting to the computer and processed signal coming out of the computer. And that’s because software processes signal in chunks. Bigger the chunk means bigger latency, but fewer chunks, so less going back and forth to read and write them. However, with smaller chunks you need to read and write more frequently, which requires faster computer. Our goal is to have the latency as low as possible, or at least low enough for us to notice. Most modern computers are powerful enough to handle low latency audio processing with a reasonable number of effects on your guitar and with couple of tracks. Having a better, faster computer will obviously help bring the latency down and enable you to run more effects on more tracks simultaneously, but it can be reasonably low even with a moderate PC having a dual core processor and 4GB of RAM.
I’ve been using a 6 years old laptop with similar specs without major issues. There are however things to be careful about. My other laptop that has very similar specs had decent latency, but was making very audible click sounds every few seconds. I later discovered that that series of Dell laptops had a bug in BIOS that made them less suitable for real time audio processing over USB ports. Since they were already few years old, Dell stopped supporting the series and never issued the necessary BIOS update. The issue rendered the otherwise perfectly good laptop into a useless junk, at least as far as software modeling is concerned.
The bottom line is, unless there’s an issue with drivers, most modern computers will do fine. Do your homework before making the purchase, try to find any issue reports online for that particular computer or major components, like motherboard. If you already have a computer and you get clicking noise or latency issues, try updating the BIOS to the latest version.
Sometimes getting optimal audio performance means having to optimize the computer for that particular use. For example, I had issues with my laptop when I was using the latest and greatest ATI Catalyst drivers for the graphic card. It was good for graphics, but for audio – not so much. When I uninstalled the ATI driver and let Windows install generic Microsoft drivers the issue went away. Be prepared for weird and counter-intuitive issues (and resolutions) like that. Some devices make cause conflicts on the USB bus and cause audio dropouts or clicks. Sometimes you’ll have to disable them while you use the computer for audio processing. Be prepared for debugging in case you need to tweak the system so it can run audio processing smoothly.
There are gazillion interfaces to choose from and there is no one “right” choice. As with any other purchase, do your homework and investigate if people are using that particular interface the way you intend to use it. Some interfaces are perfectly fine otherwise, but are less suitable for guitars. Check the forums if anyone complains about clipping the input of the interface with a guitar. For example, Scarlett 2i2 interface I tried worked OK, but didn’t have enough headroom on the instrument input which made it go into clipping when used with high output guitars. That’s not good. Try to find people who use it with similar computer like yours and check if they had any issues. Some interfaces have issues with AMD devices, some prefer USB3 over USB2, some are the opposite. Try to Make sure that it will work with your system. Other things to consider are features that you may need in the near future. How many inputs would you need? Try to leave some room and avoid getting limited there. I saw benefit of having two inputs when I recorded guitar from two sources at the same time – through DI and through the mic. If I had a single input interface, that kind of setup wouldn’t be possible. It’s also common for acoustic guitars to be recorded through the on-board pickup and regular mic at the same time. This also requires two inputs. If you plan to sing at the same time, that’s another input. Do the math and leave enough room.
Noise level is another aspect of the interface to consider. When playing guitar through an interface we will often add distortion to the signal which will amplify any noise generated by the preamp. Try to get the one that has lower noise floor.
Another thing to take into account are drivers for the device. Good hardware is useless without good, stable drivers that are making the best out of the hardware. Some well built devices have surprisingly crappy drivers that look like they are put together in the last minute and barely work. I try to avoid those. Most interfaces these days have native support for ASIO drivers, which offer much better performance than standard WDM (Windows Driver Model) drivers. It’s possible to use ASIO4ALL and have any device with WDM drivers appear like ASIO, however I prefer to have native support from the manufacturer and use dedicated drivers.
I ended up getting the Native Instruments Komplete 6 which has everything I need and there some. It’s well built, both in terms of hardware and drivers. Having a headroom of +8.6dBu (the aforementioned Scarlett 2i2 has +4dBu), it can take signal from a hot guitar without clipping.
After some time I also got Focusrite Scarlett Solo for my second computer, so I don’t have to switch the other interface all the time. It’s not as nice as Komplete 6, but does the job OK and cost half as much.
After processing, we’ll want to hear the results. For that we’ll need either a pair of headphones or a pair of speakers (or both). We want the headphones and/or speakers to be as transparent as possible and not color the sound, so we can hear exactly what happens with our signal. When purchasing, focus on studio monitoring headphones and studio monitoring speakers, as they are designed to have flat frequency response and not favor any frequency range. As with anything, more expensive models will often do that job better. Investigate the market, read review and try to find a model that suits your needs and wallet. Avoid headphones and speakers that boost bass or alter tone dramatically in any way. I’ve been using Sony MDR-7506 for almost a decade and love them. They are comfortable to wear, sound great (by great I mean neutral) and they are very durable. After 7 or 8 years the leather pads started flaking, but I replaced the pads with nice plush Beyerdynamic pads that fit perfectly. In addition to these, I also purchased a pair of Beyerdynamic DT 770 PRO headphones. They sound really good for monitoring while I’m playing, but I find them to color the sound way too much to be useful for mixing. They are a tad bass heavy and treble is a bit subdued, so mixes I make on them tend to sound harsh pretty much everywhere else.