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Old 03-17-2023, 12:40 PM
AcousticDreams AcousticDreams is offline
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Default Recording your Acoustic guitar: What Absolute Humidity does your guita sound best at?

I have been on a quest to find out what conditions my guitar will sound best at. After all, we spend a lot of time investing in Acoustics panels, Microphones & preamps. Yet, How much moisture in the air has to make some difference in how the sound will travel through the air. Shouldn't it? Think of that moisture vapor as little particles in which the sound hits.

This is completely different subject matter than how humidity effects your guitar stability. That is Relative Humidity. A confusing subject matter on its on. As it turns out RH is the determining factor and the not Absolute Humidity(Although one would think the opposite). A complicated matter for sure, but to sum it up Relative Humidity percentage changes, will create Vapor pressure. In turn, this effects the transport of moisture. Which in turn effectsmEquilibrium Moisture Content of the wood.(EMC).

But let us forget about that. I only mention this as to not be confused with the subject matter at hand, Absolute moisture in the air.
" Absolute Humidity, a measure of the actual amount of water vapor (moisture) in the air, regardless of the air's temperature. "

We can figure out Absolute humidity by the Temperature and Relative humidity conversion charts. , 42% RH at 75 degrees, has less water in the air when compared to 42% RH at 90 degrees. And at the opposite end, 42% RH at 50% will have less moisture than at 75 degrees. Warm air holds more moisture at the same RH level. Cold Air holds less moisture at the same RH level.

Over the course of a year...I notice that on some days my guitars sounds better than others. Sometimes the RH is at 40%, and sometimes it is as 55%. Unfortunately I took no notes as to the Temperature in which I was playing. To save money I use heating and air conditioning as little as possible. So my house might be anywhere from 60 degrees in the winter, to 85 degrees in the summer.

Now that I understand the difference from Relative Humidity and Absolute humidity:

I would like to get your personal observations on What temperature and RH your guitar sounds best at. Or maybe you don't notice any difference at all? Why am I so interested in this? So I might be able to control my house climate when it is time to record. To get the best audio recording I can make.

The Swing of AH percentages might not make leaps and bounds differences on most days. But there are those weeks where I do notice that slightly duller sound. And then, there are those weeks where the Guitar just sounds crisper & bigger. Have you not noticed this too?

And from those of you whom work at pro studios, is there any effort to keep a specific RH at a certain temperature for those studios?
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Old 03-17-2023, 01:56 PM
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My take on this has evolved to: whenever Im comfortable with the temp and humidity, then my guitars are, too. Whatever they sound like at that point….be what it may.

As an aside…you cannot separate out relative and absolute humidity. The adjustment factor, of course, being temperature, which also effects the speed and efficiency of sound wave propagation. (And also barometric pressure to a lesser degree!). Remember: PV=nrT. Its all related.

But of course, these humidity threads do help support the popcorn industry!
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Old 03-17-2023, 02:15 PM
AcousticDreams AcousticDreams is offline
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Originally Posted by dnf777 View Post
…you cannot separate out relative and absolute humidity. The adjustment factor, of course, being temperature, which also effects the speed and efficiency of sound wave propagation. (And also barometric pressure to a lesser degree!). Remember: PV=nrT. Its all related.
Added variables. Love new info that can help solve the puzzle. Temperature effecting the speed & efficiency. I did not think of that.

"Lowering the temperature of a substance makes the motion of the wave particles more sluggish. The particles are more difficult to move and slower to return to their original positions. Therefore, sound travels faster at higher temperatures and slower at Lower temperatures. "

Hmmm? I wonder then if both the air particles and the actual Guitar String material, are both effected?

Ninety percent of the time, on my guitar playing days, the guitar sounds plenty good. But then there are those exception days, where it just sounds even better.

And who is to say that faster is better? Not always the case. Sometimes it seems on a slightly brisk day, with lower RH the guitar shines.
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Old 03-17-2023, 02:20 PM
Rudy4 Rudy4 is offline
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I keep the humidity in the house between 40% and 50% with the whole house humidifier and central air.
The only time when I notice any change in the tone of my guitar would be that occasional foray out on the porch when there's actually a fog in the air. (I'm not going to be doing any recording in that environment, though.)

Just for my own information I checked a couple of references and they state that the speed of sound increases only by one third of one percent when the humidity raises from basically zero to 100%, therefore it's not a factor in how we perceive sound. The more salient property of high humidity is actual number and density of water molecules which can absorb some of the energy that sound is composed of.

Last edited by Rudy4; 03-17-2023 at 02:30 PM.
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Old 03-17-2023, 02:34 PM
Sev112 Sev112 is offline
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Playing and listening I think are different, esp in higher humidity environments
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Old 03-17-2023, 02:49 PM
AcousticDreams AcousticDreams is offline
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Quote:
Originally Posted by Rudy4 View Post
I keep the humidity in the house between 40% and 50% with the whole house humidifier and central air.
The only time when I notice any change in the tone of my guitar would be that occasional foray out on the porch when there's actually a fog in the air. (I'm not going to be doing any recording in that environment, though.)

Just for my own information I checked a couple of references and they state that the speed of sound increases only by one third of one percent when the humidity raises from basically zero to 100%, therefore it's not a factor in how we perceive sound. The more salient property of high humidity is actual number and density of water molecules which can absorb some of the energy that sound is composed of.
The question at hand is about the temperature & RH. As the science states, Absolute Humidity varies with Temperature. Thus more or less vapor particles in the air.

Is your House temperature consistent in temperature? Or does it vary, and by how much? If you house temperature stays fairly constant...then yes, I would expect very little to no change in sound, with a 40 to 50% RH.
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Old 03-17-2023, 02:54 PM
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You mention variables... Rudy mentions perception of sound. Tbh, I'd argue that there are so many more things that affect the sound of a guitar, and lots of them have nothing to do with the guitar or the humidity. Your current health, state of mind, other noise or distractions, etc. probably color your perception of sounds as much, or more so, than a few more molecules of water here or there. Maybe an unpopular take, but there it is.
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Old 03-17-2023, 03:23 PM
AcousticDreams AcousticDreams is offline
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Originally Posted by Chipotle View Post
You mention variables... Rudy mentions perception of sound. Tbh, I'd argue that there are so many more things that affect the sound of a guitar, and lots of them have nothing to do with the guitar or the humidity. Your current health, state of mind, other noise or distractions, etc. probably color your perception of sounds as much, or more so, than a few more molecules of water here or there. Maybe an unpopular take, but there it is.
No doubt all of those effect. Heck if you not feeling good, hay fever, sinuses blocked, blood pressure is up, I am sure it effects you hearing through body constrictions. If you have had a bad day, then perceptions are mostly likely off as well.

And of course, how new your strings are makes a world of a difference. I just put on a new set last night and my guitars sounds heavenly right now.

Still, the amount of vapor in the air in relation to temperature has to have some effect. Everything makes a difference.
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Old 03-17-2023, 07:11 PM
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I tend to think more about how wet or dry the guitar is than about the water content of the air. I read a lot about how a guitar that’s been sitting in a humid room for a while will become dull sounding because more wood moisture negatively affects the tone that vibrating wood can produce. So a dry guitar should vibrate more freely, which would effect a clearer tone.

But how long a dry guitar’s tone would take to degrade from sitting in a wet environment is an unknown to me.

So it seems the questions are, what affects tone, and what are the effects of moisture (air or wood) on tone?

Or, what’s the best way to effect a pleasing tone, and would playing a thuddy guitar cause a player to take on a sad affect?
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Last edited by b1j; 03-17-2023 at 07:20 PM.
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Old 03-17-2023, 07:38 PM
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Quote:
Originally Posted by b1j View Post
I tend to think more about how wet or dry the guitar is than about the water content of the air.
That's correct. A guitar that's been sitting in 70% humidity for a month isn't going to sound better simply for having brought it into a room with 40% humidity. Wood takes on and releases moisture. That's what changes the tone. I set my humidifier to keep my house in the 40%-45% range through the winter. That keeps my guitars sounding great and I really don't see a need to be more precise about humidity in my house than that.

To put some perspective on the issue of a guitar drying out, back in the mid-90s, before I knew anything about humidity and how guitars can get damaged, I met a luthier at an open-mic and he took a look at my guitar. My top was sinking and I thought it was string tension that caused it because I was an idiot at the time so far as guitar upkeep was concerned. He showed me how the bridge was lifting and said if it gave way, it was likely going to cause even more damage to the top. He said he could repair the guitar and probably get Martin to cover the cost (he's a Martin authorized tech still although he's moved his shop up to southern Vermont). He said it would take a few weeks and that most of that time was going to be taken up by slowly raising the moisture content of the wood.

When I got it back, it was playing better than the day I bought it. That was the day I bought my first whole house humidifier. My guitars have rarely seen a day in more than 20 years when the house dipped below 40%. It only will happen if a humidifier gives up the ghost and I have to order another. But on the rare occasions that has happened, I put a couple of big pots of water on the stove and kept it the humidity from bottoming out too badly.
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Old 03-17-2023, 09:00 PM
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My thermostat, three feet from the door of my guitar room, reads RH. I notice that over the course of a 24-hour day the RH can dip to 35% some days. But that only lasts for a couple of hours. It always rises at least into the 40s and often hits 50% even when we’re using the furnace.

I go with the assumption that RH fluctuations within a 10 percentage point range in a daily cycle may actually be good for a guitar’s long-term seasoning. Based on exactly zero evidence, other than the existence of killer-sounding vintage guitars. Like Bill Maher says, “I don’t know this for a fact, but I know it’s true.”
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Old 03-17-2023, 10:37 PM
runamuck runamuck is offline
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Two of my guitars, one a Martin OM and the other a classical made in New York, (spruce and BRW that was cracked when I bought it) sound best when the humidity is low, between 20 and 30%. The others don't sound different to me no matter what.

Unless the the rh drops below 20 or so they're all left out of their cases all the time.
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Old 03-18-2023, 12:08 AM
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https://www.bessemeter.com/blog/mois...idity%20levels.
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Old 03-18-2023, 03:38 AM
jim1960 jim1960 is offline
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Quote:
Originally Posted by rick-slo View Post
Scott MacDonald, who is mentioned in the article is a friend of mine and the luthier I was referencing in my previous post.For about 20 years, he did all my instrument work. About 7-8 years ago, he moved his shop up to Chester, Vermont. For any kind of repair work on fretted instruments, Scott is as good as they come.
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Old 03-18-2023, 04:08 AM
EZYPIKINS EZYPIKINS is offline
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I can't tell you the actual humidity #. As I don't use a hydrometer. When Humidipak's start to get hard, I'll change them.

If recording, I might have to tweak the truss rod a bit, one way or the other, to help with any buzz.

As far as humidity, when it's time to do acoustic tracks, I do the track regardless.
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