Possible mobile podcasting studio configurations

In my attempt to find out more about Edirol's R1 battery operated digital audio recorder and whether it could be the centerpiece of a good mobile podcasting studio, I was looking for people that might have some experience with the device already. Over in the MP3 forums in CNET's Reviews channel is a gentleman that goes by the handle "criggs" who has published a significant amount of information about his experience with the R1 that might be better than any review that you can find. I tracked him down and have spent quite a bit of time with him on the phone and in e-mail and a lot of the information that he has published comes as direct result of his interactions with the folks at Edirol. It's worth reading the entire thread if you think you'll need a decent portable recording studio.
While searching for podcasters who may have had experience with the R1, I found a post by Jeff of the This and That with Jeff and Pat podcast indicating that he might've purchased one of the Edirol units but that turned out not to be the case. He's still researching his options. Here's an edited-for-context-and-bloggability brain dump I e-mailed to him that talks about all the different products I'm looking at and the issues that I'm trying to comfortably manage when going mobile with my podcasts.
Jeff,

For nearly the same price as the R1, there's also the Marantz PMD660.

Regarding the lack of digital inputs eg: S/PIDF on some of these portable devices, that's true, they lack them. Once you go to digital I/O, I've noticed that the price goes way up.

Someone that goes by the name of CRIGGS has been posting stuff over on CNET Reviews. He has an R1 and there's probably no consumer out there right now who knows more about it than him. He apparently records opera music with it and based on my conversations with him, he's happy with it. But he also knows its limitations very well and has spent a significant amount of time with Edirol on the phone and in e-mails. One thing that's cool about it is that you can see the audio levels on the R1's display so you get an idea of what sort of sound you're getting.

Another way to go mobile with the flexibility of having digital or analog inputs is to haul around a Firewire-based notebook computer with M-Audio's Firewire 410 or Presonus' Firebox. I've tested both extensively for podcasting. They have analog I/O, Firewire-based multi-channel audio I/O (a big advantage because these mixer-like devices can draw their power from the notebook's battery), S/PIDF and MIDI. They're both the same price and as best as I can tell so far, the M-Audio has more to offer (both however have their downsides). I have a full review in the works.

Also, for recording, I'm testing an iRiver H320 which has line-in, line-out, and live pass through from ins to outs when recording (which, amongst other things, allows you to monitor what you're recording with your headphones). It doesn't have any visual audio indicators and CRIGGS will tell you that seeing levels is a must have (I agree, hearing it in the headphones isn't enough). There's an interesting little do-hickey to see levels on an iRiver that I found while searching the Web. I might get one. In terms of figuring out how to mix down several audio sources into it, I just bought an Azden Cam-3 handheld mini-mixer through Amazon and will be giving it a try. It can mix three mini-plug (1/8", 3.5mm) stereo sources into one and has level controls for each source but they can't amplify as best as I can tell (no power source). Only cut back.

That's not very digital, but for going mobile, it might work out. To make it work, you'll need to preamp your microphones though. I'm looking into something like this or this as a multi-person mic setup for ad hoc situations in the field. They're basically the same thing. They split a stereo line by putting separate lavalier microphones on the left and right channels. So, with the Cam-3, you might be able to lav up six people. Or, if you wanted, you could lav up four people and use the remaining stereo line to bring some audio clips in with any mini-plug capable audio device (MP3 player, CD player, computer, etc.). I haven't tested this approach though and you may have to play around with the gain situation between the recording device (H320, R1, or whatever) and the preamps to make sure you don't overdrive the input on the device if that input is also amplified. According to CRIGGS, the R1 has a mic-in jack (amplified) and a line-in jack (not amplified). With preamps, you're probably best off going into Line-In.

The downside is that with the Cam 3, you get one level control for each left-right pair. If you take one left/right pair and lav up yourself with the left and Pat with the right and you two speak at different volumes, you won't be able to level the sound between the two of you. The solution, if you had six people, might be to pair them up so that your loud talkers were paired together, and your soft talkers were paired together. Then level everybody out with the level controls on the Cam-3. Any mismatches within pairs and you might have some final sound quality issues that have be dealt with during post-production. For example isolating the soft-talkers and applying software based gain. That gain will apply to any noise as well which means that if you apply post-production gain to one voice and not the others, you may hear the noise level come up each time that person talks.

David
In the follow up e-mails, Jeff said he'd seen the Marantz unit, but had concerns about it's 16-bit encoding limitation (the R1 goes up to 24). CRIGGS chimed in to say that he's been recording live opera at 16 bit without noticeable degradation, noting that 16-bits is standard for CD-based audio. There are other issues as they relate to 16 vs. 24 bit that hopefully, I'll get to in my Podcasting 101 series.