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Is it possible to get 120 db dynamic range from recording to listening room?

Blumlein 88

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Can you record a performance, play it back in your home, and get 120 db of dynamic range in the playback?

Let me start at the beginning, where the recorded performance takes place. I'll ignore electronic soundscape creations where obviously the answer is yes.

I'll steal this from Amir's postings. Who stole it from Dolby I believe.


1564205784754.png


We see that our hearing thresholds actually are not too far from noise levels in some concert halls like the Davies Hall in the graph. So those can be quiet enough or nearly so that we'd hear silence from the venue itself. At our most sensitive mid-band we get down to 0 db SPL and a little below. The noise is a little above, but we can hear into it some anyway. So let us say this is close enough to say yes. If some orchestral or other recordings can peak at 120 db SPL we could hear down to 0 db SPL in quiet portions. Though not while music is playing.

Next step is the microphones. Can they be quiet enough? They have self noise. There are some that get close to 0 db SPL equivalent self noise (4-7 db). Some that reach that with A-weighting. So on the low end yes with A-weighting. Or very close to it as far as what we could hear. I'll will say not many do, and most used for recordings will fall shy by 10 db or more. Plenty of microphones can cleanly record SPL levels above 120 db. Some well above it. So I'd say yes if you use the right mike, but usually we've now lost 10 db on the low level end of the scale. So we are usually looking at 110 db of range now being available.

So we are at 110 db left or maybe, maybe if the stars align 120 db. The microphones have to feed a microphone preamp. What happens there. Well if you use gain in the preamp, the gain amplifies the noise as well as the signal. An EIN spec, Equivalent Input Noise is pertinent here. A good one might have -128 dbu EIN with 150 ohm output impedance microphone (which most condensers are). Sounds good. The limit in all this at this point is the thermal noise which is determined by the output impedance of the microphone. At 150 ohms that will be -131 dbu which would be theoretical perfection. However this spec is usually given with 60 db of preamp gain. And it doesn't mean we have 128 db of dynamic range. It means we have a noise level of -68 dbu, and if you subtracted the 60 db gain that is what you'd get if the input without gain were this quiet. You might think if the microphone is sensitive enough, and you could turn down all the gain to zero then we'd get 128 db to work with. But usually microphone preamps don't have their best dynamic range with 0 gain. So what can we get?

To keep from being too confusing I'll skip over some stuff, that if there is interest can be discussed further. With just the right microphone, with just the right sensitivity with some attenuation and low level gain you'll be hard pressed to exceed 110 db dynamic range between the preamp noise, microphone noise and gain levels that amplify that noise. And you'll have to be very, very careful to extract that much. It actually would be very, very rare and difficult to exceed 100-105 db here. More than 100 db is rarely seen. You know when you hear a minimally miked recording, and it starts where you hear the sound of the space of the hall open up before you hear any music? If we had kept our noise levels low enough you wouldn't hear that. It would be effectively silence or close to it. I've made recordings and hear the space prior to the music and thought, "good you can hear where it was, the size of it". But actually it wasn't that noticeable in person, and the musicians often react with the opinion the recording has noise in it. And they were right.

So at this point with all our lucky stars I'm saying you might manage 110 db, probably not above 100 db. So at this point I'd answer the question of the thread topic with No you can't get 120 db into your room. Can you really get 110 db in your room with peaks at 120 db? Well now we have to play all this on a DAC. Let us say we have one of the excellent DACs Amir has tested which has 110 db of dynamic range and SINAD as our source. Alright. Actually a 110 db DAC and 110 db recording would give us 107 db. So we'll need one of those DACs pushing 120 db for us to get close to our mythical 110 db range for our recording.

And then we send the signal to the power amp. Which will provide something like 20-26 db of gain. Which pushes up the noise floor by that much. So how much is left. Looking at something like the Benchmark or some of the Hypex or the new one from Bruno et al, we might actually have something between max power and noise of approaching 130 db, and if we subtract the gain of the input noise level we'd have maybe 105, maybe, maybe, maybe 110 db which preserves our source signal range. And this would be if max power coincides with max output of our connected speaker and it could do 120 db SPL at this level. Those are all possible, but very few combinations will manage it. And this still only gets us 110 db of dynamic range, not the 120 db we were shooting for. Sure in movies or synthetic creations gain riding and such we might get the 120 db, but in the mythical minimally miked super quality stereo recording we can't get there from here. And how many have a speaker that can do 120 db? I find most top out around 105 to 110 db if they are clean. These are pretty darn good speaker that will manage that.

My own Soundlabs might in the midrange get you to 105 db, but will need 500 watts or so to do that. Of course we don't usually need that much in the midrange. Usually big power is need in the lower frequencies. So is this entire exercise a bit daft? With our hearing thresholds at lower frequencies being some 20 db higher maybe with 120 db SPL levels we really don't need more than 100 db anyway. Rarely will music have those levels in the 3-5 khz range where our hearing dynamic range is greatest.

I'll add a final bit about recordings. Do we have any that reach even 100 db range within them? Just as an example, 2L which actually isn't super minimally miked, they use at least several microphones, analysis of their recordings indicate in the silence just prior to the music, the level is only about - 60 dbFS. Remember the sound of the hall? In the moments before music, you hear those halls, and they ramp up the level, but the hall is at - 60 dbFS. They are likely using more than low gain levels on the microphones and this is where the noise of the hall is coming from. In some of my own recordings this is pretty typical for hall sound. I've a few that do a little better than this, but nothing that exceeds about 70 to 75 db.

So, I don't claim to know all the answers, and maybe I've looked at some of this wrong. I hope this post will kick off some interesting discussion among those knowledgeable and experienced with such things. And I hope those which aren't can also post and raise some interesting questions, maybe some interesting and embarrassing questions. So don't hesitate to post an opinion, or a crazy question or to point out where I've messed up in my thinking.
 

amirm

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And:

1564210430229.png


There is text in there in how B&K techniques to reduce self noise could be applied to recording microphones, thereby producing noise that is 5 dB lower than threshold of hearing.
 
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Blumlein 88

Blumlein 88

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I've a couple microphones several decibels quieter than the Schoeps. The sensitivity plays into it some as well. The Schoeps is also not as sensitive as some others including the quiet ones I have. So the gain needed for recording will often erode that figure in the graph above. As I said in the initial post, it is close to, but not quite there. You'll probably have to throw 20 db gain at least on the Schoeps and that moves it effectively that far up the graph in terms of noise.
 

Willem

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This of course ignores the noise in the listening room. My hunch is that investing in a quieter room is probably the best strategy for the consumer. So we have sound damping double glazing, brick walls, muffled ventilation openings and even those not at the side of the house facing the road, ultra quiet mechanical ventilation (thus far we do not need airconditioning), extra quiet water pipes etc. All of this is cheap and easy with a new house but quite impractical for an existing one, of course.
 

RayDunzl

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MC_RME

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There are several tests available that can easily be done with headphones to check your personal total hearing dynamic range. With an unrealistic ping sound from 0 dB down to -120 dB you might get near those 120 dB (AFAIR I managed 112 dB), but with everything else you are lost. Fact is that once you hear a loud passage your hearing becomes insensitive for a few minutes. Example: before you start the music you hear the low level fans of electronic equipment - after the next crescendo no more. IMHO 90 dB is a more realistic number of what we need to hear the loudest peaks without noise in between the tracks. And based on history and existing recordings I wouldn't wonder if even 80 dB is enough.
 

JJB70

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This of course ignores the noise in the listening room. My hunch is that investing in a quieter room is probably the best strategy for the consumer. So we have sound damping double glazing, brick walls, muffled ventilation openings and even those not at the side of the house facing the road, ultra quiet mechanical ventilation (thus far we do not need airconditioning), extra quiet water pipes etc. All of this is cheap and easy with a new house but quite impractical for an existing one, of course.

True, but it is also interesting how we tune out constant background noise and do not notice it unless there is a change. I spent quite a lot of years working at sea and initially when you board a ship the background noise is extremely intrusive (HVAC especially) yet very quickly you just stop really noticing it. Similarly a lack of noise can be as obvious and draw attention more than noise itself, I always found it difficult to sleep on the first night off the ship as it was too quiet. I suspect that if I measured my home the results would be at odds with my impression of living in a very quiet house (well, when the kids are out...…).
 

StevenEleven

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Can you record a performance, play it back in your home, and get 120 db of dynamic range in the playback?

[ . . . . ]

So, I don't claim to know all the answers, and maybe I've looked at some of this wrong. I hope this post will kick off some interesting discussion among those knowledgeable and experienced with such things. And I hope those which aren't can also post and raise some interesting questions, maybe some interesting and embarrassing questions. So don't hesitate to post an opinion, or a crazy question or to point out where I've messed up in my thinking.

I am very certainly non-expert, but I do have some questions, and just a nagging feeling that I do not agree with an underlying premise of part of the reference material that is being quoted, but I have not put my finger on it yet so that I can state it clearly.

The big (by my line of thinking) question that comes to mind, that to me throws a wrench and a new variable in the whole discussion, and is not an original idea, but is based on something I have read as common knowledge asserted by recording and mastering engineers: Is the same SPL subjectively louder in smaller rooms?
 

Frank Dernie

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And based on history and existing recordings I wouldn't wonder if even 80 dB is enough.
That matches my experience.
It also begs the question how important is it to be able to hear the "silence" between movements in a performance. In my own recordings the "silence" is full of coughing and shuffling and not silent at all, in fact is often louder than the quiet parts of the music where most of the audience keep a bit quieter, thankfully. I haven't been through all my recordings looking though.
 

SIY

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Re: mics, are there any that will do 120 dB and 0 dB SPL? At least the ones I'm familiar with will do one or the other, but not both.
 

jazzendapus

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Are the noises generated/amplified during the different stages Blumlein 88 mentioned essentially random, full spectrum white noises? One of Amir's pro-hi-res arguments, that is backed by that first graph in Blumlein's post, is that environmental noise can be pretty low in particular frequency ranges, so can that be true for different recording/production stages as well?
 

maxxevv

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Re: mics, are there any that will do 120 dB and 0 dB SPL? At least the ones I'm familiar with will do one or the other, but not both.

If that's the case, then two mics with the two ends of the spectrum can be used and the recorded input be merged using software.

Not that difficult at all in this modern era.
 

StevenEleven

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We really need big-league recording and mixing and mastering engineers for a valid discussion on this. What many of us imagine goes on in state of the art recording and mixing and mastering may be pretty close to fantasy. We don’t know what we don’t know. Just looking at it from the back end (reproduction in the home) or speculation as to what is or conjecture as to what could be done based on very isolated consideration of what a mic is capable of and what software is capable of is not going to result in a realistic or informed discussion. Nor is simply comparing what goes on at a live performance as compared to what a mic is capable of and a speaker is capable of. Taking for granted what goes on in the middle from mic techniques to pro recording media and equipment to mixing and mastering can result in a largely fictional narrative and set of assumptions, aka, wild speculation, IMHO.
 
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SIY

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If that's the case, then two mics with the two ends of the spectrum can be used and the recorded input be merged using software.

Not that difficult at all in this modern era.

Have you tried to do this?
 
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Blumlein 88

Blumlein 88

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Re: mics, are there any that will do 120 dB and 0 dB SPL? At least the ones I'm familiar with will do one or the other, but not both.
The Lewitt LCT 540 sub zero is about 4 db unweighted and something just below 0 A-wtd. I've a Shure KSM44a which is 4 db A-wtd. The Lewitt will do 135 db spl without padding. The KSM44a will do 134 db spl without padding. Rode NT1a is 5 db SPL A-wtd, and will reach 137 db without padding. There are a few more models with similar performance. Which of course doesn't quite reach both ends in answer to your question.
 
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Blumlein 88

Blumlein 88

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Are the noises generated/amplified during the different stages Blumlein 88 mentioned essentially random, full spectrum white noises? One of Amir's pro-hi-res arguments, that is backed by that first graph in Blumlein's post, is that environmental noise can be pretty low in particular frequency ranges, so can that be true for different recording/production stages as well?
Generally noise in electronics and environments is pink or even leaning toward brown. Most noise is in the lower frequencies and less in the higher. That seems to be generally the case all around.
 
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