Basic Settings Rethought

[A440]

I went to a concert I didn't consider crucial and brought along my NHF-800 to do some experimenting with Manual Volume.

It was amplified acoustic, with bass fiddle but no drums, and it turned out to have enough light so I could see the display during the show .

With High Sensitivity set for my:

SoundPro BMC-2----->Radio Shack Headphone Volume Control--->Mic-In

I found I could crank it up to about 21/30 before overloading. I'm still going to throttle it back to 15/30 for loud rock, but 10/30 was playing a little too safe.

Next time I have the opportunity I'll also test it with Low Sensitivity, which should probably push the manual settings up into the 20s/30 with the RS attenuator.

[dex Otaku]

If levels were low enough for that in that situation - all you're doing by using the RS attenuator is adding noise to your recording by forcing yourself to turn up the recording levels. Also, using 'high sens' adds quite a bit of preamp noise even if you are using low manual-set levels.

While I have not yet found any situation that might need attenuation [other than recording sounds loud enough to seriously damage hearing if they were sustained], if I were ever using passive attenuation I'd try going without first, then with after. This wouldn't be appropriate for every situation [especially if stealthing] but that's what I'd do when possible.

edit:

It's also useful to think of the fact that when you're using the passive attenuator, you're causing a drop not only in the signal level from the mic, but also in the bias voltage from the MD - meaning you're actually decreasing the total dynamic range [maximum SPL sans distortion] of the mic if you're using the MD to power it. It would probably only be a few dB, but if you're using the attenuator to compensate for really loud levels to begin with, you're basically just causing more problems in this case than solving any.

On the other hand, it's a cheap solution - and if you're using a battery box, self-powered mic, or dynamic mic [which requires no power] then you're not really doing any harm. In all of these cases, though, it might be simpler to bypass attenuation and just use the line-in if levels are that high to begin with.

[A440]

I realize the attenuator is theoretically inelegant, Dex, but all I can say is it works for me.

Maybe you're using less sensitive mics than my usual SoundPro BMC-2 binaurals. I often use earplugs at rock concerts--I'm not a headbanger--but I also get distortion on the MD well below that level.

With the NHF-800, I recently recorded a rock show at a small theater--not particularly loud--without the attenuator at Low Sens, Manual 10/30. It would have been barely audible through line-in, guaranteed. The level meter stayed well below the right-hand dash. But sure enough, every bass-drum hit distorted, just like it used to on my MZ-N707. The slapped bass at the show I just recorded would likely have had the same effect.

I simply have not had that problem with the attenuator. The mic isn't overloading, the preamp is, which is why I want to limit the signal before it gets into the mic jack.

I've read what you've said about Low vs. High Sens and the added preamp noise, so I am going to try Low on my next outing, which means I probably will keep Manual even higher. But the attenuator stays in the picture for awhile--perhaps until Gerry Bolda builds one that's not as flimsy or staticky as the RS one. If there is added noise from it, it's easily drowned out by the ambient racket of a live show.

[mgdimo]

Wow Mr. "Tuning Fork!" I must commend you on your gentle and diplomatic handling of the self-admitted Mr. "Snarky." You tell it to the mod! Uh, Dex, I still highly value your opinion and think you're great!!

[dex Otaku]

Wow Mr. "Tuning Fork!" I must commend you on your gentle and diplomatic handling of the self-admitted Mr. "Snarky." You tell it to the mod! Uh, Dex, I still highly value your opinion and think you're great!!   

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hahaha.. concert A is good at the diplomacy, sure.

[A440]

It's not about diplomacy, it's about honesty.

We're all groping here for the best ways to use a piece of equipment that is at once a technological marvel--a palm-sized PCM recorder!!! amazing!!--and a frustrating, quirky, user-indifferent gadget with very clunky software.

Would that some of us had a research shelf full of all the MD models, a broad selection of mics and mixers, and all the test equipment that Dex knows how to use (and I don't). As is, we have to compare notes on what we each get with our individual setups.

And one reason I like this forum is that we can experiment and share results with people all over the world. For me, they are experiments, never the last word.

When someone who's brand new to MD asks how to get started, I'm happy to offer settings and procedures that have worked for me: Do this, use this number. But if someone has better settings or methods, I'm not going to be insulted--I'm going to try them and see if they're better than mine. It's not an ego thing.

Since Dex and I are using essentially the same setups--NH700 vs. NHF800, in-ear binaurals vs. basic binaurals made by the same manufacturer from the same mic capsules--I am curious about why our results differ so much. Perhaps, Dex, having them placed inside your ears shelters them somewhat and adds up to lower sensitivity?

Sorry to get all philosophical on yo' ass. Anyway, to get back to the topic at hand, I'm curious about what you think of my new recording at livefrommd of loud rock, low sensitivity, 21/30.

[mrsoul]

Hey A440! I am psyched that I ordered the same mics. I actually sold the Giant Squids because they are cardioids and pick up too much noise when using them in stealth mode. I wanted something without a battery box attached and I look forward to trying something new when in stealth mode. That RS attenuator is something I will add as well. Nonetheless, I should be able to do some basic comparison testing because a good buddy has the Giant Squids here in town and I can get them for some comparison testing. I will post the samples on my server once I have the mics (ordered today) and some samples ready. That sample you posted yesterday sounds good enough without the hassle of extra equipment. I still have the AT822 when stealth is not the issue.

[aamd]

I use the TFB-2 which I believe are 7 db more sensitive than your BMC-2. With the 900s biasing and using the low sensitivity setting and 10/30, the mics will clip just below 0 db. If I were to turn up the sensitivity above 10, I will only be reducing the overall dynamic range. (The noise floor goes up consistantly as you turn up sensitivity.) I think the controls are about 2 db per step, so with the BMC-2, you should be good up to about 13.

While setting a level higher than 10/30 results in louder recordings, it is at the risk of earlier clipping. I prefer not to risk it. If the recording is too quiet, raise the volume in post processing;.

[A440]

The difference is that I also have the attenuator between the mic and the preamp, and it cuts the signal significantly.

I have run the mics in directly at 10/30, Low Sensitivity, and gotten clipping, so I've pretty much given up on recording amplified music without the attenuator (or a battery box if I feel like carrying one and I know it's going to be LOUD). As far as I can tell, it's generally not the mics that are clipping but the pre-amp, so feeding it the reduced signal from the attenuator means there's room to raise the Manual Volume.

I wish one of the electronics experts here would measure how much the attenuator dampens the signal when the volume is fully up and describe how to build a more robust one with that same level of attenuation--or market one (hint hint). The adjustability of the Radio Shack was useful with the MZ-N707, which had to pause to change volume, but now its static is a liability.

[dex Otaku]

It's not about diplomacy, it's about honesty.

Indeed.

Would that some of us had a research shelf full of all the MD models, a broad selection of mics and mixers, and  all the test equipment that Dex knows how to use (and I don't).  As is, we have to compare notes on what we each get with our individual setups.

Funny thing is - I don't have any of those things either. I also don't own a single piece of test equipment, other than my computer, which can't produce totally accurate results in any sense other than using itself as a reference. [The results are still useful in relative terms, though they're not accurate in the sense that those achieved using real test equipment would be.]

Since Dex and I are using essentially the same setups--NH700 vs. NHF800, in-ear binaurals vs. basic binaurals made by the same manufacturer from the same mic capsules--I am curious about why our results differ so much. Perhaps, Dex, having them placed inside your ears shelters them somewhat and adds up to lower  sensitivity?

Having them in my ears would not change their sensitivity or dynamic range, really. Since the elements are omnis, this shouldn't change the average level at each mic that much. I've also used mine paperclipped to my jacket as I see others using mics like the BMCs.

I think the real issue here is that you're simply recording [aggregately] louder sources than I am - though the loudest [aggregate] source I've recorded so far was a punk concert, within 4m of the speakers [beside the sound board, with very little crowd in front of me as attendance was low], with the mic plugged directly into the Hi-MD, low sens, manual levels at 9/30 - but with no attenuation. I experienced no distortion problems. [Or at least, no distortion problems caused by *my* equipment, heh ]

In any case, my point was really to indicate that using the passive attenuator without a battbox can [but not will, necessarily] exacerbate the distortion problem rather than fix it. This depends mostly on whether the source is close to the mic's peak SPL at a given bias voltage or whether the preamp is just getting overloaded, which are separate issues.

Clarification, then:

* if the sound is loud enough to be close to the mic's peak SPL, passive attenuation might make things worse rather than better.

* if the mic is below it's max SPL but the preamp is running out of headroom, passive attenuation is just fine [though in any case, if you're recording a loud source, use low mic sensitivity on the recorder].

I'll have to wait to dl your new recording - until I get my main machine back. This linux box I'm running has a SB16 ISA PnP in it but I'm pretty much refusing to listen to anything through it, lest it corrupt my ears with hiss and distortion.

I have run the mics in directly at 10/30, Low Sensitivity, and gotten clipping, so I've pretty much given up on recording amplified music without the attenuator (or a battery box if I feel like carrying one and I know it's going to be LOUD).

It just depends on how loud the source is, as you already know [and have said]. Which is why I think the difference in our experiences is simply that you're recording louder sources. I don't often get to attend amplified concerts, and haven't had any problems at the ones I've been to so far - though I know that if I went to anything larger than is usually around here [a small place that virtually no known acts ever come to], I'd have to use a battbox to get a clean signal as their PA would be virtually guaranteed to exceed the maximum SPL of the mics at MD's bias voltage.

I wish one of the electronics experts here would measure how much the attenuator dampens the signal when the volume is fully up and describe how to build a more robust one with that same level of attenuation--or market one (hint hint). The adjustability of the Radio Shack was useful with the MZ-N707, which had to pause to change volume, but now its static is a liability.

Generally speaking, the signal drop of any variable attenuator like the RSVC is at or close to zero when it's "fully up." In theory, the loss should be zero - pretty much all volume-control [logarithmic taper] type potentiometers are "fully open" at one end and "fully closed" at the other [in electrical circuit terms, where closed = 0dB attenuation], but we're talking about potentiometers, so you will likely be getting less than 1dB drop in the signal].

As for its static [assuming you mean that it's worsened with age, i.e. got dirt in the pots' contacts] - RadioShack and others sell electronics cleaning spray, which you can use to clean the pot in the attenuator by simply spraying it in and then turning/wiping it through its full range several times.

[A440]

[Generally speaking, the signal drop of any variable attenuator like the RSVC is at or close to zero when it's "fully up." In theory, the loss should be zero.]

Dex old friend, you're theorizing again. There is definitely a drop in sensitivity with the RS. Full up, which is the only way I ever use it any more, still lowers the signal. It's just a little el cheapo connector.

[As for its static - RadioShack and others sell electronics cleaning spray]

Turning the volume knob, even brand new, is staticky. Then, after considerable use, static occurs constantly, either because the knob lets in dust and the like or it's wearing down. So I heave the HVC into the nearest trashcan and get another one. Which is why I would love a closed, non-variable one that matched the RS.

[dex Otaku]

Indeed. Or, you could save te money you've spent on all the HVC's and buy a battbox/attenuator or battbox/preamp and totally bypass all those issues.

[A440]

In the spirit of scientific inquiry, I did a test on the RS attenuator, full up.

New York subway car (inside), SP-BMC-2.

Without attenuator, AGC, 6-7 bars on the NHF-800 meter

With attenuator, 3 bars.

At $6-7 a pop, it'll be a while before it's as expensive as a battbox/attenuator, much less a preamp. And by then, Gerry Bolda will no doubt be selling the perfect attenuator. (Right?)

I have a battery box, but I do like not carrying an extra box around.

[mgdimo]

I have a battery box, but I do like not carrying an extra box around.

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Kind sir, please chime in on this subject here.

Many thanks.

[andrewhall]

This is a very interesting discussion - I'd like to see more on the subject aside from the issue of the attenuator.

Dex wrote (up top)

"Also, using 'high sens' adds quite a bit of preamp noise even if you are using low manual-set levels."

Is there any advantage to using low sensitivity at a high setting - say 28 - 30 versus high sensitivity at a lower setting? Unlike most of the above discussion I generally am recording quiet to very quiet sounds.

Andrew

Edited February 19, 2005 by andrewhall