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Gear / Technical Help => Ask The Tapers => Topic started by: taperdave1998 on March 13, 2025, 11:11:35 PM
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Alright, here comes my (likely dumb) question and slight story:
I'm going to be taping a show in eight days. Formerly used an H4n Pro, but we're in the era of 32-bit float! May as well embrace it. I bought a Zoom F3 last week that arrived faulty. It wouldn't spit out my micro SD card. Sent it back, received a new unit. Same exact thing, even worse actually... and this is a SanDisk card, not some crappy Onn./dollar store card.
So...
I ordered an H1 XLR! I've been stealthing with the H1essential all throughout 2024 and never had any weird issues with spitting out the exact aforementioned memory card.
My mics are sE8s with cardioid caps.
The sE8s have a sensitivity of 25 mV / Pa (-32 dBV). The H1 XLR has a max input of +4 dBu (which is the same spec as the F3, interestingly enough).
Do I need to use my pads to tape this show? Or rather, should I? I have no way of knowing how loud this concert is gonna be, as it's for a band I've never seen in a theatre I've never been to. Will be taping from behind the board at 7-10' in the air, likely DIN.
In essence, just because my mics can handle 139/149/159 dB, I want to make sure I'm clipping the actual recorder. Thank you very, very much.
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I will let the people who might know that gear answer the question but would recommend you doing a practice show at a bar or something just to see if it works. If it doesn't you get a second shot.
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At 25 mV/Pa, those mics will output 4 dBu at about 127 dBSPL. That's really loud, like "worrying about my hearing, even with decent protection" loud...
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25 mV/Pa is pretty sensitive and will produce a relatively hot output, but as Aaron mentions 127dB is very, very loud. I'd not expect you to have a problem unless recording on stage close the the drumkit where transient peaks can be extreme.
(https://sengpielaudio.com/MicrophoneMaxOutput.gif)
^ Ignore the blue highlighted row/column which is just an example for 20mV/Pa.
That table sourced from here: https://sengpielaudio.com/calculator-transferfactor.htm (https://sengpielaudio.com/calculator-transferfactor.htm)
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That’s a fantastic chart.
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This thread, and the chart, have been very helpful to me so thank you for the original post and responses so far!
Given that I’m recording, most often, in 32 bit with a Mixpre 6 ii or Zoom F3, my only concern when setting up my mics (from a level perspective), is ensuring I don’t overload the analog stage.
Based on the above I am understanding that with the mic sensitivity, the chart, and a very approximate level of the show volume I can establish the output level of the mics.
Is there an easy way to establish the input level at which a recorder will overload for these devices (e.g., is this a published spec) or is there an easy general level that is considered safe across all devices?
Thanks in advance, this thread cemented an important concept for me and will allow me to record loud sources stress free going forward. ;D
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This thread, and the chart, have been very helpful to me so thank you for the original post and responses so far!
Given that I’m recording, most often, in 32 bit with a Mixpre 6 ii or Zoom F3, my only concern when setting up my mics (from a level perspective), is ensuring I don’t overload the analog stage.
Based on the above I am understanding that with the mic sensitivity, the chart, and a very approximate level of the show volume I can establish the output level of the mics.
Is there an easy way to establish the input level at which a recorder will overload for these devices (e.g., is this a published spec) or is there an easy general level that is considered safe across all devices?
Thanks in advance, this thread cemented an important concept for me and will allow me to record loud sources stress free going forward. ;D
I guess don't really understand what you're saying. The MixPre-6 II has a listed spec of "Mic XLR: +14 dBu." This is significantly higher than the F3, H1 XLR, FR-AV2, etc. which all share the +4 dBu max in from mic XLRs. I'm under the impression your MixPre can handle virtually anything you'd throw at it and that it would be difficult to clip the analog in.
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^ I think you just answered my question. The max level at the input of the F3 is +4 dBu and the Mixpre 6ii is +14dBu and that’s the max input level at the XLR in to avoid analog clipping. Is that correct? If so, is that at the line in or mic in mode?
Apologies if I’m missing something obvious here.
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^ I think you just answered my question. The max level at the input of the F3 is +4 dBu and the Mixpre 6ii is +14dBu and that’s the max input level at the XLR in to avoid analog clipping. Is that correct? If so, is that at the line in or mic in mode?
Apologies if I’m missing something obvious here.
The MP6-II specs are:
Mic XLR: +14 dBu (limiters on or off)
Line XLR: +28 dBu (limiters on or off)
You're all good. I myself have very little technical knowledge on the matter myself, but this makes the most sense to me. What mics you running?
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^ I think you just answered my question. The max level at the input of the F3 is +4 dBu and the Mixpre 6ii is +14dBu and that’s the max input level at the XLR in to avoid analog clipping. Is that correct? If so, is that at the line in or mic in mode?
Apologies if I’m missing something obvious here.
The MP6-II specs are:
Mic XLR: +14 dBu (limiters on or off)
Line XLR: +28 dBu (limiters on or off)
You're all good. I myself have very little technical knowledge on the matter myself, but this makes the most sense to me. What mics you running?
Thanks this is helpful. I don’t run limiters and I think they only matter for digital levels (not an issue with 32 bit). I didn’t realize the specs you noted were max level at the xlr before analog clipping. That’s what I needed to know so thanks again!
I have a few sets of mics with different sensitivities which is why I asked. If I’m going to record a really loud band and think I could be close to a stack, or on stage near drums, mic selection is one thing (along with a pad or an attenuator) that could help.
Line audio cm4s/om1s
Km 184s
Akg ck61-3
Scheops mk22
I also run CS HEBs sometimes but that is 24 bit through an edirol r07 so levels matter at both the analog and digital stages in that scenario and the noise floor is also more of an issue which is why using an F3 where you meant to almost “not worry about levels” is such a mental adjustment for me.
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^ Generally speaking, unless you have both very sensitive mics and a very loud source, you will be OK with most current recorders. The exceptions would be if you are quite close to a high SPL instrument (snare or bass drum, horns, guitar cabinets turned up high, etc.) or have too much analog gain dialed in (which isn't an issue in a well-designed 32-bit floating point device).
Also, the better limiters have an analog stage. With my first generation MixPre-6, I always set levels a bit on the conservative side, but engage the analog limiter just in case I misjudged something. I think it has only kicked in once or twice. Better safe than sorry, though.
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Thanks Aaron,
I didn’t realize that the limiter was at the analog stage. It sounds like there is an opportunity to figure out how to set it, at a level that should never kick in, but below the max input level of the the analog in, and this would eliminate the possibility altogether.
Thank you for helpful tip!
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^ There are several flavors of limiter: analog, digital, and hybrid. If you are recording in 24-bit, with analog limiters, it can work well. I am unsure to what extent digital or hybrid limiters are beneficial. The market-speak can be hard to interpret...
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^ Thank you, I will investigate further.
So it sounds like the answer to the OP’s post is.
1) they probably don’t need a pad in all but very extreme cases (e.g., on quite stage close to drums, right next to stack at very loud show)
2) using line in in these situations the mic pad could be used (or switching to line in)
3) there MAY be an opportunity to use an analog limiter but this requires further investigation as some of them are digital (which wouldn’t help) and the way they are described can be misleading in some cases
Thank you again to the OP for asking this question. Very helpful info here.
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Thanks Aaron,
I didn’t realize that the limiter was at the analog stage. It sounds like there is an opportunity to figure out how to set it, at a level that should never kick in, but below the max input level of the the analog in, and this would eliminate the possibility altogether.
Thank you for helpful tip!
The limiters are disabled in 32bit float mode, for obvious reasons.
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Real world example-
I run relatively sensitive mics into a first generation Zoom F8. Using those sensitive mics on stage I found I would occasionally illuminate the peak indicator. Was never a problem out in the room where peaks are limited through the PA. Unlike later generations of the F8 recorder, first gen only allows for use of phantom power in mic-in mode via the XLR inputs. Line-in is always via the TRS inputs without the option of phantom power. Ordinarily I would switch to Line-in mode with phantom engaged to lower input sensitivity sufficiently and achieve sufficient headroom, but because phantom power is not available I couldn't do that.
Instead I use mic-in and engage the hybrid limiter. The hybrid limiter works by first engaging a pad on the input which lowers levels enough to prevent any overs I'd normally encounter. The limiting is applied with a variable ratio that engages progressively - the few peaks that would have gone over when recording on stage are caught and just slightly limited with a low compression ratio. However, if an unusually high SPL event were to occur the limiter will engage more and more aggressively as the signal approaches 0dbFS. Using this arrangement, the mics will now clip before the recorder.
At first I was disappointed that engaging the limiter in this way was necessary, and considered upgrading to a later gen F8. However in testing I found the hybrid limiter well implemented and unusually transparent sounding, and since it rarely needs to do anything and basically acts only as a transparent safety mechanism, I have no problem keeping it engaged across all channels all the time.
The limiters are disabled in 32bit float mode, for obvious reasons.
No. The marketers imply that its is obvious, but its not. The analog front end of the recorder is separate from its ADC architecture and file storage format. If an analog input to ANY recorder is hot enough to overload the recorders analog input circuitry, the recorder's input sensitivity will need to be adjusted, a pad-engaged, or limiting applied to prevent it from overloading. If the current version of the Zoom F8 (the F8 N Pro, which does feature 32-bit float recording) did not have the option to provide phantom when in line-in mode and if I did not have the hybrid limiter engaged, I would still encounter the same problem with high-peaking SPL sources on stage causing overs even with the recorder set to write 32bit float files.
That problem is more likely to be encountered with inexpensive, smaller 32-bit float recorders than it is with F8, MixPreII, etc.
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> The analog front end of the recorder is separate from its ADC architecture and file storage format. If an analog input to ANY recorder is hot enough to overload the recorders analog input circuitry, the recorder's input sensitivity will need to be adjusted, a pad-engaged, or limiting applied to prevent it from overloading.
This is a key point (aside from the fact that past a certain point, limiting can't prevent overload in an analog front end; it protects only the stages that come after it, such as the A/D. But the possible benefit of a limiter is, uh, limited since it is just as easy to overload the input of an analog limiter as any other analog circuit--and limiting changes something essential about the sound of a recording, and requires judicious application).
-- Just wanted to add that throwing the pad switch on a condenser microphone reduces the signal/noise ratio of the recording by the amount of the pad, since it reduces the signal levels without lowering the noise floor of the electronics. Those switches are for emergency use ONLY. If you reasonably anticipate that a microphone's output levels could overload your recorder or preamp's inputs, get some in-line resistive pads (typical values are 10 and 20 dB) and put them at those inputs when setting up for a loud event. They knock down noise exactly as much as they knock down signals, thus preserving your s/n ratio. They're cheap, they're rugged, and they don't interfere with phantom powering.
Or depending on your recorder, it may or may not have settings for input sensitivity that work like the resistive pads that I'm talking about.
There's a ~40 dB difference in sensitivity between the most and least sensitive microphones on the professional market, and the maximum SPL of live sound itself varies by (say) another 40 dB from situation to situation. The gain setting of an analog mike preamp MUST be at least approximately correct to avoid clipping and/or the addition of extra, potentially audible noise. That's regardless of whether the rest of the recorder is 16, 24 or 32-bit.
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i recorded a show last sunday with my h1e using the internal mics. i was 5 feet away from the amplifiers. it was so loud that i wore earplugs. i was worried that it would be distorted, but it came out fine and real good stereo separation.
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-- Just wanted to add that throwing the pad switch on a condenser microphone reduces the signal/noise ratio of the recording by the amount of the pad, since it reduces the signal levels without lowering the noise floor of the electronics. Those switches are for emergency use ONLY. If you reasonably anticipate that a microphone's output levels could overload your recorder or preamp's inputs, get some in-line resistive pads (typical values are 10 and 20 dB) and put them at those inputs when setting up for a loud event. They knock down noise exactly as much as they knock down signals, thus preserving your s/n ratio. They're cheap, they're rugged, and they don't interfere with phantom powering.
Great info here. I've been using the pad switch on my mics for some time not realizing there was a better option. Any "ideal" attenuator value? Or just whatever is needed to give some headroom on the input?
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-- Just wanted to add that throwing the pad switch on a condenser microphone reduces the signal/noise ratio of the recording by the amount of the pad, since it reduces the signal levels without lowering the noise floor of the electronics. Those switches are for emergency use ONLY. If you reasonably anticipate that a microphone's output levels could overload your recorder or preamp's inputs, get some in-line resistive pads (typical values are 10 and 20 dB) and put them at those inputs when setting up for a loud event. They knock down noise exactly as much as they knock down signals, thus preserving your s/n ratio. They're cheap, they're rugged, and they don't interfere with phantom powering.
Let me know if this is a red herring, but I think my question applies.
I've been at this a long time and still don't quite have an intuitive understanding of the reasons for, and effects of impedance matching.
I think it's so that energy at all frequencies can transfer from one part of a circuit to the next, and not load down components to the point where they can't deliver the goods.
Does adding inline resistive pads effectively raise the output impedance of the mics in a linear fashion?
(by linear, I mean the same effect at all frequencies)
OK, I hope that was on topic. I know that the reason for using pads is so that large signals can fit in small holes, but I would like to have a better understanding of the relationship of voltage and current in this dance.
Thanks as always for the wisdom and clarification, DSatz! You rock!
8) 8) 8)