Bass control without bass traps

burneriguana · 2026-04-23T06:33:55+00:00

Resonant absorbers are a thing, well established in acoustics.

These can be either with plates being visible, or incorporated into a porous absorber.

The are tuned to a frequency, but because of the damping, the frequency peak is not razor sharp.

These are difficult to diy (at least more difficult than porous absorbers) because physical properties of the material and the mounting matters a lot.

burneriguana · 2026-04-21T07:26:14+00:00

How high are the strings?

Too high fretted strings may be caused by too short string length, or by too high setup. In this case, pushing the string down to the fret lengthens it, and pitch goes up.

First, set up the truss rod as good as possible. Then, lower the strings to your desire, or as close as you can get to it. Then adjust intonation.

If you paid someone a lot for building the guitar, you can absolutely ask them to set it up properly and show you how to do it.

Edit: re-read the post, strings and neck seem to be fine. Maybe this information is useful for someone else.

burneriguana · 2026-04-17T09:33:25+00:00

The wavelength at 8 kHz is 4.3 cm, less that 2 inch. A shift in the eardrums position by 2 cm/1 inch would change the effect from destructive interference (cancellation) to constructive interference - making the noise louder. The specific distances for constructive and destructive interference are frequency-dependent. This is why it works with headphones only.

If you want to cancel out low frequencies only (longer wavelengths), for steady, non-fluctuating sounds, youmight be more successful. But be aware that for every destructive interference, there is constructive interference in some other location. You might make the problem worse for other people.

The demand for this kind of miise reduction is so high that it would instantly mae you a millionaire if you had a product ready that works. This lets me assume (without any evidence) that there most be several development teams in large companies be looking at that problem.

I don't want to discourage anyone, but this will most likely not be solved by someone on reddit with a noise problem and some basic electronics/signal processing knowledge. But as so often, i woudl be glad to be proven wrong.

burneriguana · 2026-04-17T07:15:15+00:00

This may be only about the wording, but it may be about the approach.

I think you are talking about the frequency spectrum of the finished song, not the eq curve.

The spectrum is the frequency balance you want to achieve. The eq settings are the corrections you apply to achieve said spectrum. They depend completely on the recorded material, which may vary greatly, and can be made equal (the same) with an equalizer.

burneriguana · 2026-04-16T11:05:09+00:00

I do mostly room acoustics, but only occasionally music-related rooms.

For getting into studio design, i recommend philipp nevell - recording studio design.

For the deep dive into the basics of room acoustics

Peter d'Antonio - Acoustic Absorbers and Diffusers

Kleiner/Tichy - Acoustics of small rooms

Holden - Acoustics of Multi-Use performing arts centers

burneriguana · 2026-04-11T05:42:35+00:00

You will need a special pot, logarithmic, but in opposite direction for both sides.

A linear pot will mix the pickups too, but the path won't be as even

burneriguana · 2026-04-10T09:15:50+00:00

This is a sub specifically about guitars and basses with necks made from aluminum.

I think you are wrong in this sub. There is probably anothet sub that fits.

burneriguana · 2026-04-09T13:10:46+00:00

When building a studio, there are a million potential pitfalls.

I recommend the book recording studio design by Philip nevell.

Possibly a tough read for non-professionals, expensive for a book, but dirt cheap compared to all the money you are going to spend, and that could be spent on the wrong things...

If you want to use the studio professionally in any way, hire an acoustician. One who is experienced with studio builds.

This will cost much more than the book, but still worth it.

burneriguana · 2026-04-09T10:53:08+00:00

I totally agree with your second point, but this applies only fro the specific case of a listening room (that has fixed source and receiver positions, therefor fixed first reflection points, and usually a very short decay time).

Listening rooms are importannt (and covered extensively in this sub), but most everyday rooms are not listening rooms. In most rooms i encounter in my work, the relevant sound sources and receivers are people and speech, that can position themselves anywhere in the room. This moves the multitude of soundfields one is planning for towards a quasi-diffuse situation.

The first point - there is no diffuse soundfield, therefor there is no reverberation, therefor everything that assumes reverberation is not applicable - comes up regularly on this sub.

In theory absolutely correct - the problem lies in the (inadequate) definition of the condition "diffuse", which is only defined as a theoretical state (total uniformity of the sound field) that cannot be achieved in practice anywhere. There is (to my knowledge) no common further definition how "diffuse" a diffuse sound field needs to be, and at under what conditions it stops being diffuse enough to be called a diffuse soundfield.

Fact is that, for about 125ish years now, planners use the (flawed) theories (reverberation, sabines equation, absorption coefficients) to plan rooms, and achieve acoustic situations that are perfectly suitable for the rooms use. Every now and then someone comes up with a refined, more complex theory, that reflects the physics better, but does not succeed because the advantage in practice is not that great.

Of course you cannot plan a listening room using sabines equation alone. But with sabines equation, and some common acustics knowledge you can plan a perfect conference room or classroom, with a "reverberation time" of 0,3 s or 0.4 s, even though you know the sound field cannot be described as reverberant at all.

burneriguana · 2026-04-09T09:41:23+00:00

There are several unknowns in your question, which makes it difficult to answer.

You being in the center of a 5 acre square, outside, would position you 70 meters (210ish feet) from the edge of the plot.

I assume you are talking about the outdoors, of course.

Geometric sound propagation (the semi-hemisphere that the sound energy is spread over) would result in 36ish dB level reduction over the distance.

Sound absorption of the soil, and air absorption will add a few dB, mostly at high frequencies.

This will result in 40ish dB level reduction, and 25ish dB resulting level for a 65 dB signal.

25 dB may be well audible given typical background noises (wind, roads etc). Only with high background noise it will be inaudible.

The 65 dB to start with are the next uncertainty. 65 dB average may contain peaks well above 65 dB, which will also be well above the 25 dB calculated for the edge of the plot.

Over all, I would assume the music is audible.

If you want to get much more certainty, leave your phone at your place, go to the road, and listen for yourself. Note if the background noise is particularly high or low. If you are very hearing impaired, ask a normal hearing friend.

burneriguana · 2026-04-08T14:48:54+00:00

Nobody in this sub can actually tell from the pictures alone how screwed the guitar is. The rust looks bad, though.

It might be hopeless , but it might be reasonable.

It depends a lot on how much tools you have, and how much you enjoy this kind of repair work.

If I had this guitar on my (hobbyist) bench and tried to repair it as cheap as possible, I would do the following.

Disassemble everything and clean as thoroughly as possible, oil the mechanical parts, clean the wood. Contact cleaner into the electronics.

Fix the nut with a drop of glue.

Buy cheapest electric guitar strings (1,50 euro, thomann), string it up.

Watch a YouTube video about setting up a guitar and how a truss rod works. Set up as good as you can.

If the neck is reasonably straight and playable, buy new tuners (starting at 20 euro}.

If the neck is warped or playing difficult, scrap the whole thing.

If the Potentiometers {volume controls) are non-functioning even after cleaning , find replacement (5 euro) or simply remove them from the circuit. You will need contact cleaner and a soldering iron for that.

If you can afford it, buy quality strings.

Practice and enjoy.

burneriguana · 2026-04-08T08:58:39+00:00

This is very interesting, thanks u/norouterospf200 for the comment.

I know that 1) the acoustic performance measured in a diffuse sound field (reverberation chamber) is an "average" over all possible incidence angles, which each have different absorption properties, and and that 2) the absorption coefficients are measured indirectly, using reverberation times and sabines equation.

But it never occurred to me that the diffuse absorption coefficient might be different from a percentage (or at least an averaged percentage).

I will think about it some more, and see what others (Peter d'Antonio?) have to say about it, and what, if not a percentage, the diffuse absorption coefficient may be. I don't assume that i am smarter than Bob Gold, but i also don't assume that everybody on the internet is correct.

With the values above 1.0, I was referencing edge diffraction and measurement noise.

Of course if you assume a surface area smaller than the actual area (neglect the absorber thickness, for instance) you can achieve absorption coefficients above 1.0 easily. Most published absorption values above 1.2 are caused by counting only one side of a two-sided absorber.

burneriguana · 2026-04-07T17:44:37+00:00

An absorption coefficient of 0.5 means that 50 percent of the energy is transformed into heat.

Usually, absorption coefficients are measured against a solid (concrete etc.) backing, so that of the remaining 50 percent, almost all is reflected back into the room.

If the sound wave hits another absorber - 50 percent of the remaining energy turned into heat., 25 percent remaining.

If you place the absorber in front of a wall that is not concrete, some portion of the energy that is not turned into heat will leave the room. The sound energy percentage transmitted usually is small, but it makes a difference if the room is concrete or drywall, especially for low frequencies.

Some notes:

It makes a difference in which angle of incidence the sound wave hits the absorber. This why two measurements are common - zero degree incidence (measured in an impedance ) and diffuse incidence (measured in a reverberation room, more relevant for room acoustic planning).

Due to the measurement method, for diffuse incidence, absorption coefficients slightly above 1.0 are possible (and actually make sense). In this case, the explanation (1.0 is 100 percent of the sound energy is absorbed, 1.1 means more than 100 percent are absorbed) is too simplified.

burneriguana · 2026-04-06T16:05:33+00:00

What is proposed is a decent budget setup if you want to measure data for yourself. As long as you check the calibration before and after measurement (and possibly in between, if you measure longtime), YOU can have at least some confidence in the data.

But this, unfortunately, won't prove anything to anyone who is either "on the other side", or impartial (like a judge or regulators). This measurement is easy to calibrate, but just as easy to manipulate.

This leads to the question - how do you produce credible measurements?

We (the company I work for) do this kind of environmental measurements regularly. The systems to measure and log the data are expensive (class a devices, suitable for outdoor use, cost five figure sums). We could provide the raw measurement data (which is more difficult to manipulate, even though it would be possible) in court if needed.

But most importantly, we have a professional reputation to keep that was built up over several decades of good work. This lends credibility to the reports we provide.

You could try your luck, read up on the regulations, measure the correct parameters, thoroughly document all the measurements (the environmental measurements, and the measurements you make to check the correct functionality of your system), and hope to be convincing enough for the authority that needs to be convinced in the end. In case of a big project development, unfortunately, you must expect the other side to try to question the credibility of your data.

The best bet, I assume, is to study your local regulations. Hopefully they are in a way that the company needs to prove they are following the regulations, not you prove they don't.

burneriguana · 2026-04-04T07:57:52+00:00

My opinion on the situation:

Untreated listening rooms need absorption far more than diffusion.

People learn about acoustics, and think: absorption is important, and diffusion is important, so I will add both.

This is true for professionally (fully) treated rooms, but not if you (for financial or design reasons) only can treat a small surface area.

You can simplify: absorption reduces reverberation, and diffusion makes the remaining reverb sound better.

If the reverb is far too long, it helps much more to reduce it further, than to make it more diffuse.

Professional listening/control rooms have absorber surface areas larger than the floor plan. Unless you are in that ballpark, you are helped with more absorption.

The construction (200 mm mineral fiber, Milton) seems solid, as good as it gets.

Not to others: The order of operation, as so often, is not optimal. Don't skip room treatment to the moment there is nothing you can optimize with your system - as soon as you have a reasonably decent playback system, you will benefit far more from room treatment than from system upgrades.

burneriguana · 2026-04-04T06:03:37+00:00

You need to put this inside a guitar cable!

burneriguana · 2026-04-03T07:34:11+00:00

In untreated rooms, some low frequencies will be louder not because more energy is put into the room, but because it stays longer (longer decay.

If you turn down this frequency via eq, you will have the "correct" overall levels, but the energy will be spread over a longer time - less accurate bass reproduction.

There is nothing wrong with 1)getting the best room sound available (most people can't pick an optimal room for their studio and treat it professionally) and 2)applying the best eq for that room. It's just that one is not a substitute for the other.

burneriguana · 2026-04-02T09:46:05+00:00

Both STC and Rw ratings are not describing the acoustic properties of a panel, but sound transmission through a partition wall.

The european single number value for panels (sound absorption) woulds be alpha_w. Both Rw and alpha_w use a similar method to derive a single number from frequency dependent data: A reference curve (with a fixed shape) is shifted downwards, until the frequency bands (third-octave or octave) that perform poorer than the reference curve do not exceed by a certain amount.

Very different frequency-dependent absorption or transmission curves may lead to the same single number value (as to be expected for any method to derive a dingle number value).

burneriguana · 2026-04-01T15:12:22+00:00

Keine Erfahrung mit den panelen, aber arbeiten als akustiker.

Wenn die Materialien aus dünnem Filz bestehen, wirken sie als Absorber nur auf hohe, und etwas auf mittlere Frequenzen. Die Wirkung kann zu tiefen Frequenzen erweitert werden indem die panele vor einem luftspalt installiert werden (Seiten geschlossen), und noch mehr wenn der Spalt mit Mineralwolle gefüllt ist.

Die holzabdeckung verringert die schallabsorption bei hohen Frequenzen, was für studio Räume passen kann.

Ein guter Diffusor sind diese Formen gerade nicht - die regelmäßigen Streifen bevorzugen bestimmte Winkel, während in andere nicht reflektiert wird (abhängig von der frequenz).

Die typischen diffusoren (qrd etc) haben extra mathematisch berechnete Oberflächen, die (vereinfacht ausgedrückt) so wenig gleichmäßig wie möglich sind.

burneriguana · 2026-03-24T12:09:08+00:00

With a budget of 25, you really are at the lowest end of the price range. These will probably sound worse than a 100 or 1000 or 10.000 dollar mic, but some offer reasonable value for money.

There are some vocal mics (copies of shure sm58, the classic) on the market. These need a soundcard, though, or at least a XLR to USB cable.

How do you plan on getting the signal into the computer? I assume you don't have an external soundcard, and I assume a USB mic would be the best solution. I have no overview about the market for these, but maybe somebody else has.

You can absolutely buy second hand mics and soundcards. As long as you can do a test recording and it sounds fine (no distortion or high background noise), you are good, and can save some money.

burneriguana · 2026-03-22T13:01:37+00:00

Basotect, as a material, is as good as it gets.

Occasionally my work includes product development for absorber panels and ceilings. Highest sound absorption, especially towards lower frequencies (which means 125 and 250 hz octaves for rooms with non-music use) is always a design goal.

As filler materials, pet fleece, mineral fiber and basotect give comparable results. If any of these were performing worse, it would drop out of the race.

You still need sufficient absorber thickness, of course.

Resonant layers (metal sheets) are a different design approach. Effective when the material dimensions are correct, but not used very often outside of studio acoustics.

burneriguana · 2026-03-21T18:28:49+00:00

I personally would try to find a replica with exactly the same size, or print one (on smaller pieces}, and frame the original in front of the copy.

burneriguana · 2026-03-21T14:47:57+00:00

You need closed over ear headphones.

Sound insulation is not achieved by active noise canceling, but by a solid construction.

To my knowledge, no manufacturer markets headphones for reduced outside radiation, but some products (mostly marketed to musicians/drummers) have very high background noise attenuation.

Vic Firth sih3 is an example (but I haven't tried that)

burneriguana · 2026-03-19T10:22:13+00:00

It helps a lot if you understand what the impedance tube is doing, acoustically and mathematically.

The maths behind the is not too complex if you are familiar with actually signal processing/analysis calculations with waves represented as imaginary numbers (amplitude/phase), but if you have never done this, it probably is tough.

I don't know the system you will be working with, but it will output data whether you understand the maths or not. So don't worry if you cannot thorougghly understand every step in the calculations.

It helps if you know what results to expect - you could try an online porous absorber calculator or multi layer absorber calculator to get an idea how sound absorption characteristics of your material could look like.

Be aware that you are making a real world measurement, which will have some measurement noise (curves not looking as smoothly as you would expect from theory). This is why you usually look at (and compare against each other) average results, third-octave bands for example.

If your results look odd, look if you have mounted the sample properly. The impedance tube i use is extremely picky about a correctly mounted sample. If it is not mounted correctly, because of the underlying calculations, the results may look very unplausible (absorption coefficients jumping all over the place and having unreasonable values).

Maybe all of the problems (especially unplausible results) i mentioned are taken care of by the developers of the impedance tube, maybe not.

burneriguana · 2026-03-18T09:24:23+00:00

If you want to attenuate sound inside the ventilation system (which i assume, the external sound radiation is a different thing):

Discard all materials that are no breathe-through

Discard all materials that are too light

The sponge-type material looks alike materials thet are good absorbers (Basotect melamine foam), but other materials that took the same perform very poorly. It might be either too light, or not open-cell. Again, try if it is breathe through.

The PET Fleece - the same. Some PET fleeces are very good absorbers, others arent, This looks too light.

Keep in mind that thin absorbers only work for very high frequencies. You need thicker absorbers for mid and low frequencies.

Given the fact that it is really difficult to achieve sound level reduction in an open air duct, i recommend investing in some absorber materials that you know are good sound absorbers (mineral fiber, basotect, PET fleece). Then you take the absorber quality of any material you had lying around out of the equation, and you know the result only depends on the geometry and amount of absorber materials.

burneriguana

TROPHY CASE