“I am a guitar player with a home studio. I recently read about a technique to record electric guitars that would allow me to concentrate more on performance during the tracking session. Since I am the “engineer”, “producer”, “writer”, and “performer” of the music, I also spend a lot of time positioning mics and EQing my amp during the tracking session. The technique I read about suggests recording my guitar signal direct (while monitoring through the amp) to get the best performance. Then, later when my ears have cooled off, the “direct” dry signal from the recorder goes directly to the guitar amp(s), where I can audition different amps, settings, effects, re-position mics, compress, etc. without the guitar strapped to my back! Here are my questions: Since the impedance from the recorder will be a balanced, low impedance signal, and my amp expects a high impedance, instrument level signal, will a direct box in reverse convert impedances as required? How about a mic preamp with input and output controls … I’ll just “turn it down low until it works”? And lastly, I have a digital MDM setup (DA-38s), will the latency for digital conversion be noticeable?”
This is an effective recording technique and we see more and more people doing it all the time. In some DAW systems there are some excellent sounding amp modelers that work this way, effectively eliminating the guitar amp from the equation. In that environment all the details about level and impedance are handled for you. For those still working in the MDM/mixer paradigm things are not so simple.
A passive direct box will work in reverse. Active ones usually will not. Your idea “may” work, but there are other significant variables to consider. The interaction between your guitar and the guitar amp is part of the sound you get. When you mess with that you mess with your sound. The best advice is just to try it. I think you will find it is not easy to duplicate the sound of your guitar going straight into your amp, but you may very well be able to get close enough for the technique to be effective.
A direct box between the recorder and the amp isn’t going to do it. The level coming out of the balanced output of a DA-38 is too high. Bring the signal back to your mixer like you normally would. Then you can just use a direct out or aux send to get the signal to your amp. It will take some experimentation to get the level just right. You may find that the signal is too noisy this way. It depends on the electronics of your mixer. Just turning down an output, or some other gain stage, doesn’t always turn down all the noise. If this is a problem for you then you are going to have to buy or build a pad to reduce the signal down to a level acceptable for your amp after it leaves the mixer. Once the level is low enough you can also try a passive direct box in reverse to see if it helps any. The transformer inside it will vaguely resemble the load your guitar would normally present and could help. It’s not likely to make a big difference though. You will need a direct box or some type of preamp to get the signal from your guitar into the mixer initially.
The latency for most A/D and D/A converters is minimal and shouldn’t be a problem for you. There is also some latency associated with the recording circuits in the DA-38, but the cumulative effect of all of this shouldn’t be enough to be noticed unless you are extremely sensitive to this type of thing.