Schuyler Monroe Hupp

Thanks Karl! Okay, so the LR pulls around 1 Watt, and the UCR411a pulls about 1.6 Watts, about 1/3 more power than the LR. I didn't know that the UCR411a batteries were in parallel; thanks for that too! Lately I've been using Sony NP-F 970 batteries since they seem to have a slightly higher energy density than the NP-1. I use two in series to create a 14.4 Volt supply; those are rated at about 6.3 Ampere hours. The NP-1 system looks to be simpler and more convenient though. I'm still experimenting... :-)

Anyone with an LR and a DVM who would be willing to measure current demand? :-) I have been looking at and trying to compare the LR and the UCR411a and noticed that Lectrosonics does not list the current demand for the LR, though they do suggest a 4 hour operating time on 2 AA alkaline batteries. Since the power rating of a battery in Ampere hours is load dependent, it's not straight foreword to glean current demand with the information given. Typical alkaline AA cells are rated at around 2000mA hours for a 200mA discharge rate, and about 1200mAH for a 500mA discharge rate... So with that information you can get a rough figure for current demand for the LR being between 300mA & 500mA... So the LR appears to require more operating current than the UCR411a (which are listed at 180mA, which should go for more than 6 hours on two 9v 500mAH batteries). The implication is that if you wanted to bag a hand full of LR's, even though they are attractively small and light weight, it might not be as power efficient as the UCR411a, and would result in one having to change batteries more often.

"...if the quality is really subjectively different from a SD744t I might consider differently." The 702 and the 633 are subjectively different to me, but perhaps not to others. I know of no easy way to quanity the difference in a way that would convince others, and I'm not sure I would really want to. What I would recommend is to rent, beg, or borrow the machines you are interested in, put them through their paces, then make the decision on the basis of your own preferences. Having had a chance to compare the 702, 633 and the Maxx, I would say that they are all superlative. My preference would be to use the 702 or the Maxx for stereo recordings... Maybe. But that preference might change as I learn more and gain more experience with them and would depend on the end use of the recording. For dialogue recording and mixing and where features & functionality were the main thing, the 633 is just amazing to me, but that being said, the feature sets are different and it may be that the Maxx or Nomad would have the features that would best fit your needs. I've never even had my hands on a 744T... :-P But from what I've read, it would be difficult comparing the 633 with the 744 on the basis of anything other than sonic characteristics, as their features are so different.

"...how important is "stereo imaging" for the work that the majority of us do in production?" Of course, you're right. For dialogue recording... For monophonic recording of dialog, even if you have a great ear, all you're going to hear are subtle colorations from one preamp / machine to another, and the differences in tonal color between microphones say for example, or cueing & polar response, are going to be much greater. And everyone's voice is different anyway. I was thinking along the lines of binaural field recordings, which are really fun, though they don't have much of an audience. Recording acoustical instruments, music recordings, I think it's worthwhile to strive for transparency there too, though I know very well that the vast majority of cabinets and horns out there are just not capable of much in the way of stereo imaging anyway. Things improve though... I'm continually amazed at how much audio has improved in recent years. When I visit friends who have big "home theater" systems, well, the audio bar has really been raised for television, is what I'd say. Far cry from the little speakers they used to have along with those fuzzy cathode ray tube television sets. Now it's just amazing...

I love that Richard Feynman quote! He was an exceptionally wise and rational man.... Yes, it's easy to fool ourselves! It is also very difficult, if not impossible to describe subjective experiences to others who have not shared the same experience. You can quantify things in many different ways, but they are all just dancing around the thing you're trying to share, if it happens to be a subjective experience. Words are not the same as the things, but sometimes it's all we have. :-)

I really like the headphone amps in all of the recorders, though my ears seem to prefer the one in the 702. I also have outboard headphone amps that uses high performance op amps (OPA227 or 2132 for example). From my experience, driving the load is when a lot of distortion can be introduced, and that's where I've been able to improve my listening experience. It is splitting hairs, I have to admit, but it can be fun to listen to! There are entire web sites dedicated to building headphone amps. There's an ongoing debate regarding the subjective benefits of high performance headphone drivers too, as not everyone can hear the difference. I would say that if you can't hear the difference, or don't care, then don't bother, but if you can, then by all means! At least for me, I enjoy having that little extra clarity, even if it is subtle (e.g. improvements in stereo image).

So I just finished a long test listen of the three machines and I just gotta say, they are all wonderfully engineered, just amazing how good they sound. Yeah, I recorded on to all three machines simultaneously with the same mics and then loaded all of the wave files on to each of three machines and listened to them closely. Still a totally subjective test. Anyway, each appears to have its own character, varying degrees of subjective transparency, with some of those differences manifesting as ever so subtle variations in stereo imaging, and at least to my ears, in relation to time domain performance and the way that can affect the reproduction of complex reflected sounds in the stereo field. If you can afford it, at least to my thinking, it would be nice to have couple of different machines to choose from. Say, one for dialog and another for stereo field recordings? The main thing I've learned is that the machines are all amazing and that the sonic differences are very small, so I would be happy to use any of them. I will mention briefly that the subjective AB double blind tests that would indicate that people can't hear differences in distortion below a certain threshold, e.g. the popular 1% THD figure, is not valid, I think, in relation to stereo program material. When distortion manifests in the time domain, as differences phase in a stereo field, the human ear - brain combination, is capable of hearing very subtle differences, perhaps an order of magnitude lower than that, if not greater. Monophonic, yes, the 1% figure is about right, but with regard to phase distortion in the context of stereo, it's considerably lower than that.

The playback issue is an obvious and crucial one. So I'll see if I can get some good wav files and then compare them with the best playback audio chain I can put together, at very least, the -same- playback chain for both files. What I do know is that just monitoring the inputs, I can hear a subtle difference, that the 702 seems better than the 633 in terms of stereo imaging. BTW, I used the line outputs on both machines with my own headphone driver and the results of the tests were the same, with a stereo image from the 702 that just leaps out from the earphones... :-P

This is pretty much a seat-of-the pants, practical test. Highly subjective, right? But I like the idea of splitting the mics to the recorders under test and keeping everything else the same. So far, I am loving the sound of the 702 and the features of the 633. Wish I could have both in one machine!

Having the two recorders going at the same time is cool, I like that! When I get the Maxx, I'll see if I can set it up that way and then post the wav files. I am really tempted to pop the cover on the 633 to see if it would be possible to improve performance by way of simple re-chipping, but I don't want to kill the warranty. Maybe in a year or two I will disect one of those things... :-)

The idea of playing them back on monitor speakers is a good one; however, I don't have any audiophile monitors that are really capable of reproducing the timing dependent dimension of a great stereo image. I have JBL LSR4328P's and though they are an excellent reference monitor, they don't have much in the way of timing dependent imaging... That being said, loudspeakers never have as good a stereo image as headphones due to acoustical crossfeed, which tends to mask the image, though with a good near field monitor set up, with an early reflection free zone (at least with speakers better than mine) you should be able to hear it~!

The idea of comparing the two resulting test files on a computer is a good one, but so far as I know, the subtle nuances of timing that are involved in stereo imaging, beyond the slower amplitude differences, are not visible in the envelope, or even discernable to the human eye at the waveform scale, i.e. oscillosope. At least for me, I have to either listen to it, or measure the distortion, and the set up for measuring distoriton at those low levels is very tricky, something that I don't have the gear for, so I rely on the manufacturer's claimed figures. So far, the timing related stereo imaging capabilities of most of the gear I've used has a very tight correlation with distortion figures. e.g. 663 says 0.09%THD and the 702 says 0.004% THD and the 702 has much better stereo imaging. Or, say for example, the ideal theoretical distortion of a 5532 op amp has distortion figures that are a couple of orders of magnitude higher than say, a TI/BurrBrown OPA2132 or an OPA227, and at least with my ears and my setup, the stereo image always sounds better with the lower distortion IC. In a typical chain, where the op amp is not working hard to drive a load, this is not as big of a problem, but when driving say, a pair of headphones or a speaker, it can make a huge difference, at least from my experience.

I don't have access to a Nomad, but will be receiving a Maxx in a week or so... Do you reckon the analog chain and converters are the same in those two machines or not? I'd love to see a schematic! In fact, I'd love to see a schematic for any of this stuff. I haven't asked, but my guess is that the manufacturer's would rather not hand out drawings for these things. I've done a few minor repairs on 702's and was really scratching my head trying to figure out where the front end preamp IC's were. Those things are very tightly packed. Extremely well made.

Posting files of the test.... Yeah, that's a good idea. Whether the test results can be heard would depend on the quality of your downstream chain though, but yeah, that would be interesting. I didn't hear any difference between the recorder line outputs and the headphone outputs. My ears are not that good. However, I was using my own headphone driver at the end of the chain, to minimize distortion in that regard. IMHO, the 700 series is far better in terms of fidelity, which I think is reflected in the distorion figures they publish, though of course the features and applications for the respective machines are different. ...

I just did some testing to compare 600 and 700 series recorders ability to render realistic, transparent stereo imaging.... I don't have a 744, but used a 702, and compared it to a 633. The mics consisted of two AT4047's in XY config, and also a MK41 & MK8 MS setup. Sources were voice & hand claps. Room was typical interior, with sheet rock walls, textured ceiling, carpet, about 300 sq ft. RT60 about 500ms, mics set up where both early and late reflections were picked up... Monitoring was via both headphone jack and XLR outputs (ABing between the two) Heaphones were 7509's and Beyer 770's. An external headphone driver with Burr Brown IC's was used achieve much lower distortions than what are normally associated with headphone drivers. Subjective results, at least to my ears and with this particular set up was that the702 has superb imaging: Open, and natural sounding, with a clearly translated stereo field that gives one the sense of a real, three dimensional acoustic space, e.g. complex ambient reflections... 633 exhibited, at least in this experiment, wonderful response and clarity, but a not so well defined stereo field, not quite the sense of a real, three dimensional acoustic space as with the 702. Interestingly, the difference in stereo imaging capability was apparent in the input monitoring mode, as well as during playback, which indicates that some of the differences are in the audio chain, before recording has even occurred. My take on this is that the performance of the 702 with regard to rendering stereo imaging, is reflected in the distortion figures. In older gear I've tested, jitter was sometimes involved, but in this case, there is significant difference in THD figures that could account for the results. Conclusion? I would say that, contrary to what I've read in some forums, the 700 series is far from obsolete. They sound amazing! Next week I'm going to compare the 702, the 633 & the Zaxcom Maxx.