Topic: R4 content, how significant if singnal to noise ratio?

[THE NIZ BIAAAAACH!]

r4 is thd of  .03
r4 pro is thd of .01
Is this a significant amoount and what do you think the differece might equate to in real world terms?

[flintstone]

More important than total harmonic distortion is the deck preamp's equivalent input noise, or EIN.  This is the noise that the preamp adds to the voltage it receives from your mics.  This noise is perceptible as background "hiss" in your recording.

EIN is usually stated in units of dBu, or decibels referenced to voltage.  You're looking for an EIN that is a low number, meaning the preamp is adding very little noise to the signal from the mics.  An EIN of -120 or lower is a very good figure.  (Example: Sound Devices 722) An EIN of -100 is OK. (Example: Tascam HD-P2)  An EIN of -60 is pretty noisy. (Example: Marantz PMD60)

As you probably guessed, preamps with better EIN are usually found in more expensive gear. 

If your source is very loud, like amplified music, then the voltage the mics deliver to the deck preamp is high.  You can keep the preamp gain setting low. The voltage of the mic signal is much greater than the EIN of the preamp, so it's hard to hear the noise.  In this circumstance you can get good recordings with a deck that has an EIN closer to zero.

If you're recording acoustic music or nature sounds, the voltage produced by the mics is lower.  So you have to turn up the gain of the preamp.  This makes the noise added by the preamp a greater component of the signal you're recording, and you're more likely to hear the hiss.  Under these circumstances, a preamp with better EIN (farther below zero) will produce a better recording.

One problem with EIN figures is that the manufacturers can fudge the test conditions to make their equipment appear better than it really is.  So use the EIN as a guide, but not the absolute truth.

And then there are manufacturers like Edirol, that don't specify EIN.  I have not used the R-4, but from the comments posted in this forum I think the R-4 preamp performance falls in the middle range, better than some but not as good as others. 

The Doug Oade modification to the R-4 improves EIN (although Doug also does not post EIN figures).  I'd purchase an R-4 from Doug so you have the option of returning it for an upgrade down the road.

Flintstone