I have some opinions and theories on this "trick" having used it over the years on both a 41 and a 42. They are herewith served with the requisite grain of salt...
I believe this was maybe discovered when someone (as noted above) had a mix going, took a break, powered down, and came in the next day and went "Wow" - those guitars sound awesome!" only to discover that the delay which was being being used for stereo chorus effect was now set to 00 ms. Despite some opinions that it can not be done on a 41, I believe that it may have actually been
discovered on a PCM 41, because the 41 came first and it does not remember the delay setting when powered down. As noted by others here, if it was just the limiter on the 42, then you could achieve this effect by just slamming any limiter and blending it.
And besides, it was taught to me years ago by another engineer, on a 41, (pre Nirvana even!)
Here is what I was taught:
If you set the PCM 41 delay time to 00 ms and 100% wet and pan opposite the mono source track and balance the two, you can create a very lush/thick stereo guitar sound that also also holds up rather well in mono and is not too 80's chorusy. Apparently, if you have a 42, you can also crank the input to get the increased limiting from that device too. But what seems to be left out above is that the delay mix control must be set to 100% delay.
In my experience, you can even blend the dry/effect channels into mono (or in-between instead of hard panned) for spatial effects and to "widen" the guitar footprint but still place it somewhere other than total pseudo-stereo. Bringing up the delay time ever so slightly can vary the effect but too much and you are just heading into flange/chorus territory.
In the interest of full disclosure, I have done the above effect on PCM 41's and 42's over the years
without the limiting since I only just learned about that here on gearslutz. And I don't have access to a 42 anymore and I don't recall intentionally slamming the 42's when I did this in the past.
So why might this effect work on these delays and not others?
I may be wrong but it's my theory that it is not just the limiter on the 42 that adds to the guitar sound, but the fact that you are setting the delay to near 00 ms and running a signal through the less than perfect sample/delay circuit of a 42 (or a 41) which alters the wave form (re-sampling) even when set to 00 ms. This thickens the original sound in a way that simply eq or compression alone cannot achieve. It is kind of grungy on its own, and kind of cool when mixed with the source track. ITB effects like echo farm or the PSP emulations can not do this in the same way. Other delays that I have tried it on, like the effectrons and SDE's don't seem to do it either. Something happens to a PCM 41/42 when set to 00 ms and then using a bit of the delay factor knob.
While the 41
is different than the 42 effect (no limiter) it is to me equally valuable, if it's a sound you're after. If you have a 41 lying around, try it, and you may want to keep your 41 (too)!
All this being said, it is just a trick, it can get old fast, and I don't do it much anymore since I mix primarily ITB, but I do occasionally miss it on a track that really needs some help.