An Observation on Humidity and Tone

[Mandobart]

The conventional wisdom is that wooden stringed instruments sound muddy when over-humidified, and tone improves as they dry out. Its been a struggle getting and keeping my instrument room at 35% RH this cold winter (I prefer ~45%). Yesterday I bought a new supplemental Aircare humdifier. This morning the instrument room is up to 40% RH and everything sounds way better; guitars and mandolins have more sustain, ring clearer and just have more sparkle.

[sunburst]

Wood, as we know, is hygroscopic. The higher the relative humidity in the environment of a wooden instrument, the higher the moisture content of the wood in the instrument.
For any wooden instrument, there is an optimal range of stiffness and density for the wood, and it is possible for the wood to go out of that range through either dryness of excessive moisture. Dryer wood is less dense and stiffer, wetter wood is more dense and less stiff... so, if conventional wisdom says tone improves when instruments dry out, then conventional wisdom is not taking the starting moisture content into consideration. If an instrument's wood has too much moisture it may well sound better when it is dryer, but OTOH if the wood is too dry it may well sound better with more moisture, and that is probably what you have going on there.

[Markus]

Living in the cold upper midwest, I have come to like my `winter tone' when the mandolin is well humidified - but when it starts to get too dry it loses a lot of warmth [and eventually the strings rattle a bit on chop chords] which to my ear gives a harsher and more brittle sound. It runs `slightly dry' during the deep winter and I think the tone shines then.

There's a happy medium IMO, as the sticky humidity of summer also tends to have a loss in tone.

It has made me wonder about this when buying my next mandolin - should I be buying from someone from my general climate? What effect would torrified/baked wood tops have on the equation [any effect]?

As I'm a one mandolin guy and played the same instrument for most of the last decade - these regular changes have become more and more apparent as I've gotten to know it's sound in and out. Being devoted to one instrument sure hasn't made shopping for my upgrade an easy task - while I'll likely keep the old one I'm going to put thousands of hours and hundreds of performances on my next one [just as I have my current]. Decisions, decisions.

[Br1ck]

I've had an interesting situation with my recent build. We have had an unusual for California rainy stretch going back to January. After about three weeks of wet weather, my mandolin has stayed in tune. When I tune up, maybe two of eight strings need a very minor tweak. Many days none at all, and the same with transporting it forty miles. Take it out of the case and it's in tune. In dryer weather, I tuned it three or four times a day, and it was much further out.

[pheffernan]

It has made me wonder about this when buying my next mandolin - should I be buying from someone from my general climate? What effect would torrified/baked wood tops have on the equation [any effect]?

In your position, I’d think about buying from someone who builds in a low humidity environment and in your general neck of the woods, namely Chris Stanley.

[pops1]

I live not far from Markus. I don't think it would make a difference where an instrument is built living here. Winter can dry out and instrument, especially if you don't humidify. Summer gets very humid, like 90%+ sometimes. I humidify and still have to raise the bridge in the winter and lower it in the summer to keep the action where I like it. I am liking the sound now at 45%, I humidify. In summer with more humidity, no air conditioning, the sound is not as nice. Especially the low end.

[kurth83]

Not sure I notice tonal difference for humidity yet, I'll keep an eye out after this thread though.

I have noticed that when the wood swells the top raises, my instruments go sharp, and the increased tension produces brighter and more powerful tone. Conversely, when they dry out and go flat (as the top sinks), the tone dies. Once tuned they seem to return to normal from what I can tell.

The thing with humidity is it takes prolonged exposure for the wood to change. When it's cold and dry here, I will have a week or so of having to tune instruments up because they were flat every morning. Same effect in reverse when things get wetter and warmer during early spring here.

[Eric Platt]

I'm with pops1 on this. When it's mid summer up here, it can be too humid for my mandolins to sound best. Also humidify in winter and most of my instruments have gotten to the point where they stay in tune if I'm careful with them.

That said, we all become used to what we have. A friend, who moved to Arizona, is now used to the sound of his fiddle down there. In the very dry weather. When he comes up here for a festival, his fiddle is no good for the first day or two until it gets used to the humidity again.

A late friend used to put his "good" Gibson away in summer because he felt the humidity hurt the sound too much.

[foldedpath]

As long as you're controlling your home environment within the reasonable humidity and temperature limits, and the builder is doing the same, then I don't think it makes the slightest difference where your instrument was made.

My one and only mandolin was made in the Czech Republic. It has a redwood top from the Pacific Northwest USA that ended up in Europe. Then the finished mandolin was sent to a store in the USA mid-west where I bought it online, and the mandolin was shipped back to the Pacific Northwest where I play it now. An amazing round trip for that top wood, and as long as I keep my home humidity and temps under control, there are no issues.

My "Irish" flute was made by a guy in Switzerland from some secret stash of a tonewood that you can't get any more (Cocus), because it was logged out from Cuba and Jamaica in the 19th Century. The flute was sold to a guy in Rome Italy who played it for 15 years, then put it on Ebay. I bought it last summer, and it was shipped from Italy over here to the USA Pacific Northwest. I've had to fuss with the tenons a little as it adjust to my home environment, but it plays fine in spite of the world tour.

Wooden musical instruments are a bit delicate and fussy, yes. But if they've been cared for well enough by the builder, and you care for them reasonably well as a player, then you don't need to match your builder's environment to your own.

[pops1]

I try to control the humidity in my environment, but in the summer I play a weekly boat cruise. The humidity on the river is extremely high on hot days and there is no way to control it. The mandolin just soaks up moisture. I started taking a different mandolin for these that has a lacquer finish instead of the varnish as it doesn't get so sticky. If you gig there is no control to be found for environment.

[MontanaMatt]

I frequently play at mountain resorts, and I notice a lag time on tuning stability when we arrive at high altitude gigs. Some are 2500 feet higher than my house. If my memory from schooling is working(questionable), r.h. has to do with vapor half pressure and temp, thus 40% is a different volume of water per square meter at different barometric pressures.

[Bob Clark]

One of the best moves I've made was installing a plumbed-in, whole-house steam humidifier unit more than a decade ago. I have a really high-end piano and I installed it to keep that instrument happy. But it also makes my nasal passages happy, my wood floors happy, my furniture happy and my mandolins happy. Sure, it cost a few bucks, but look at all the happiness!

It is made by Skuttle. It is fully automatic, even flushes itself out twice per day. And it sits under the floor, completely out of sight. Best of all, it keeps my house, me and my instruments at a constant 43% day in and day out. I think it was a great investment, especially given the combined value of my instruments.

YMMV, but for me, the peace of mind knowing my instruments are at a constant humidity, as winter temperatures fluctuate, is well worth the investment.

NFI. And I'd be happy to give mor details if anyone is interested. Feel free to PM me, as well.

[Mandobart]

I frequently play at mountain resorts, and I notice a lag time on tuning stability when we arrive at high altitude gigs. Some are 2500 feet higher than my house. If my memory from schooling is working(questionable), r.h. has to do with vapor half pressure and temp, thus 40% is a different volume of water per square meter at different barometric pressures.

Kinda close. Absolute humidity is the measure of water vapor (moisture) in the air, regardless of temperature. It is measured in the mass of water vapor per unit volume. Relative humidity is water vapor but relative to the temperature of the air. It is expressed as the amount of water vapor in the air as a percentage of the total amount that could be held at its current temperature. Warmer air is capable of holding more water vapor than cooler air, so air at 40% RH at 40 F contains less moisture than 40% RH air at 70 F. Altitude affects absolute humidity; as you get higher in altitude, the atmosphere becomes thinner (less pressure) so the total amount of water vapor the atmosphere can potentially hold is less. This has no impact to RH.

[MontanaMatt]

Kinda close. Absolute humidity is the measure of water vapor (moisture) in the air, regardless of temperature. It is measured in the mass of water vapor per unit volume. Relative humidity is water vapor but relative to the temperature of the air. It is expressed as the amount of water vapor in the air as a percentage of the total amount that could be held at its current temperature. Warmer air is capable of holding more water vapor than cooler air, so air at 40% RH at 40 F contains less moisture than 40% RH air at 70 F. Altitude affects absolute humidity; as you get higher in altitude, the atmosphere becomes thinner (less pressure) so the total amount of water vapor the atmosphere can potentially hold is less. This has no impact to RH.

Wouldn't 40% rh at sea level vs 40%rh at 7500 ft result in different outcomes of swell or shrink in apiece of wood? The amt of water molecules in a volume of air is different...no?

[lenf12]

Wouldn't 40% rh at sea level vs 40%rh at 7500 ft result in different outcomes of swell or shrink in apiece of wood? The amt of water molecules in a volume of air is different...no?

Yes!! The partial pressure of water vapor is much lower at 7500 ft. because the total barometric pressure is much lower at that elevation.

Len B.
Clearwater, FL (20 ft. above sea level

[Richard Mott]

On the seasonality of humidity here in Virginia, I have noticed my instruments sound wonderful, at their very best, twice a year—around April when the outdoors has thawed for a couple of weeks, and around October right after the fall weather first breaks. By the end of winter the strings sound brittle, and by the end of summer the instument can sound flabby. But at the start of spring and fall, wow!

[Phil Goodson]

Wouldn't 40% rh at sea level vs 40%rh at 7500 ft result in different outcomes of swell or shrink in apiece of wood? The amt of water molecules in a volume of air is different...no?

Mandobart:
So does wood lose more water as RH decreases or lose more water as vapor pressure decreases?

[Elb2000]

I just took my mandolin to a 70% rh location (CA) for 2 weeks from my home in Wisconsin. I have a whole house humidifier, but my WI indoor rh has been about 30%, and varies based on outdoor temps. This is the highest humidity my old 1920’s house will only tolerate without potentially expensive window/wall condensation problems for this past cold Feb. I noticed that the string height above the frets increased in CA, which made my Mandolin sound a little louder, and also stopped some pesky buzzing around the 14th fret. I did not measure the action height to see how the neck or bridge moved. I’m just back in WI, and since wood gives up moisture slower than absorbing moisture, I do not expect my mando to go all the way back to the Feb condition.

[Mandobart]

Mandobart:
So does wood lose more water as RH decreases or lose more water as vapor pressure decreases?

Wood loses more moisture as a result of RH lowering than by atmospheric pressure lowering. In the real world, air temperature drop usually accompanies elevation gain so this tends to raise RH while the pressure drop tends to lower it. I own instruments that spent over 100 years at higher altitude (~7000') with no supplemental humidification. No cracks or issues. YMMV.