How to trim the high frequencies on a speaker

Improving the sound quality of the midrange speakers

It is generally accepted that the sound quality of a loudspeaker is determined almost entirely by its AFC in sound pressure, its unevenness in the range of reproduced frequencies, and its harmonic distortion factor. However, subjective (by experts) evaluation of the sound of not only amateur, but also industrial sound equipment shows that speakers with good parameters do not always sound equally good.

Careful study of speakers suggested that one of the reasons of such a phenomenon could be the difference in the characteristics of the transients of the MF heads included in the speakers.

Equivalent scheme of the head

For the analysis of transients in the piston action region of the head (low-frequency range of reproducible frequencies) it is convenient to use its equivalent scheme, shown in Fig. 1а. Here Re and Le are resistance and inductance of voice coil respectively, C = m and L = s are electrical equivalents of mass m and flexibility of suspension with moving system respectively, and Re is electrical equivalent of losses on radiation and friction of suspension unit. The numerical values of the equivalents are recalculated to the electrical input of the head.

The influence of inductance Lk on its frequency and time characteristics can be neglected in the area of piston action of the head. As a result, the equivalent scheme of the head takes the form shown in Fig. 1б.

It is known that the quality factor of a circuit made of a parallel connected resistor, inductor and capacitor is equal to the ratio of the conductivities of the reactive (inductive or capacitive) and resistive branches. The quality factor of the circuit shown in Fig. 1б,

Here Gа,=1/Ra, is the conductivity of the resistive branch, ωs, = √(mC) is the resonant circular frequency of the moving head system. The quality factor (Qa) obtained in this way is called the acoustic quality factor of the head because it only takes into account losses in the mechanical vibrational system (Ra).

If, however, shown in Fig. 1b circuit is connected to a generator with zero output impedance, the considered LC-loop will be shunted by resistance Re. In this case, its quality factor is defined by the formula Qe=ωsmRe and is called the electrical quality factor of the head (its definition does not take into account the influence of Ra).

The quality factor, which is determined by taking into account the influence of the resistances Ra and Re, is called the equivalent quality factor of the head Qt. If the internal resistance of the input voltage source is zero it is equal:

And since the Qt value of QaQe is, without exception, only slightly different from Qe.

When passing from the characteristics of the electrical equivalent of the head to its acoustic characteristics, it should be borne in mind that the voltage on the parallel circuit, consisting of elements m, C and Ra (Fig. 1b), is the electrical analogue of the vibrational speed of the moving system. Thus, the more value of Re and consequently Qt at a given value of Ra, the more non-uniformity of dependence of voltage on circuit on frequency corresponds to greater non-uniformity of sound pressure developed by the head in the area of piston action.

Resonant frequencies of low-frequency heads lie inside of the frequency ranges they can reproduce, so when selecting these heads pay special attention to a numerical value of equivalent Qt of the head and if it exceeds the required one, take measures to reduce it and improve the frequency response.

The situation is different when choosing midrange (MF) heads. Their resonant frequencies lie, as a rule, below the range of their reproduced frequencies. As a result if we take the AFC of a loudspeaker by sound pressure using the traditional method (by continuously changing the oscillator frequency) the unevenness of a MF head near its resonant frequency is practically undetectable in the resulting loudspeaker response, because the resonant frequency voltage, which goes to that head, will be largely attenuated by the bandpass filter.

The real mode of MF heads significantly differs from the one considered above. The voltage of the broadcast signal at the output of the loudspeaker bandpass filter can be considered as harmonic (sinusoidal), the amplitude and frequency of which are continuously and, in general case, vary sharply enough in time. That is why the head always works in a transient mode instead of a steady state sinusoidal oscillation, which takes place during the measuring of the AFC by sound pressure.

How to wire a tweeter through a capacitor

A tweeter connection consisting of just a capacitor is called a filter or passive first-order crossover. It is called a “high-passfilter” and works as follows. The capacitance of the capacitor determines the cutoff bandwidth. This does not mean that frequencies below the cutoff will not be reproduced by the tweeter.A first-order crossover has a sensitivity of 6 dB (decibels) per octave. An octave is half that or more. If the HPF cut-off is 2,000 hertz, then the frequency that is an octave lower, ie 1,000 hertz will sound 6 dB lower, a cut-off of 500 hertz will be 12 dB lower and so on.

Because of the size and stiffness of the tweeter diaphragm, we can assume that the low frequencies will not have a significant effect on the reproduction of the high frequencies. There are more complicated crossovers of the second order, the circuit of which, in addition to the capacitor, includes a choke. They provide a power reduction of 12 decibels per octave, and third-order filters provide a reduction of 18 decibels per octave.

What kind of capacitor to put on the tweeter

To get the best sound from your speakers, you need to be very careful when choosing a capacitor. What kind of capacitor do you need for your tweeter? Chinese manufacturers of inexpensive speakers put an electrolyte with a capacity of 2-10 μf in series with the coil of the high-frequency speaker.

Products of this type are polar and by definition designed to work in DC circuits. On alternating current they do not behave quite correctly, so to connect the high-frequency speaker in a speaker system of two or three speakers, it is necessary to use film products of appropriate capacitance. If you have an inexpensive Chinese-made speaker system, all you have to do is open it up, and replace the electrolyte, with a polypropylene or paper capacitor, to feel the difference.

If the necessary capacity is not available, the necessary capacitors for tweeter speakers are assembled from several products connected in parallel.From domestic products, you can use K73-17 and K78-34. These are lavsan and polypropylene products. Type K78-34 is specially designed for installation in filters of high quality loudspeakers. It works correctly at frequencies up to 22 kHz for speaker output power up to 220 watts with 4 ohm speakers.

In order to choose the right capacitor for a 4 ohm tweeter you need to know its resonant frequency. High-frequency heads can have a relatively low resonance frequency of the order of 800-1,200 Hz, but most “tweeters” will resonate at 2,000-3,000 Hz. Capacitor values for different cutoff levels to a 4 ohm speaker are as follows:

To cut off a band with a first-order filter, you have to go above the resonance, otherwise the speaker will vibrate unpleasantly when we play the sound. It is recommended that the cut-off frequency of the filter should be about twice the resonance value of the high-frequency loudspeaker.

Hello, everyone! In this post, I decided to raise an important topic for many newbies. Let’s try to understand it, get into it, make conclusions and formulate advice. Let’s go!

It’s all about choosing capacitors for horn loudspeakers. This is exactly the question all newbies ask. We are all very smart and experienced, so let’s rephrase it more intelligently. How to choose a passive high pass filter for horn loudspeakers.

First, let’s remember what this stuff is, what it’s for and how it works?We need crossovers (filters) to cut off unnecessary frequency bands from the speaker, giving it the bandwidth it needs to work properly.There is nothing wrong with subs in this respect. Even if you give your subs the full bandwidth, nothing will happen to it. But when we are talking about speakers of any design, the crossover will determine their life, sound and durability.

Second point to understand: any crossover does NOT cut off frequencies sharply. If your high pass filter is set at, say, 3 kilohertz it doesn’t mean that the speaker will suddenly stop talking below three. The speaker will sing 2 and 1 kilohertz and 500 Hz and even 20!The whole question is how much power will be delivered to the speaker at those frequencies and how much and how fast will the volume drop outside of the crossover setting.This is determined by the cutoff order of the crossover. 1st, order (6dB/octave). 2nd (12dB/octave), etc.д. What do these dB/oct?Well there’s no question about the dB. dB-decibels determine the volume level (more precisely the sound pressure level, but whatever the point) and Oct it’s an octave. Octave is(Bellin, how to put it simply :D) Octave is a range of frequencies which is located either up to twice the frequency of the current frequency or twice less. It’s not clear. :D:D Explain with an example: Let’s assume we have a 1-st order high pass filter at 1 kilohertz (1000 Hz). Such a filter lets high frequencies through to the squeaker and cuts low frequencies. So the first order filter (6dB/oct) means that below 1 kilohertz the sound will not disappear, but the volume will go down.If let’s say our speaker sang at a volume of 100 decibels at 1 kilohertz, then below the filter setting by one octave (1000Hz/2=500Hz) at 500Hz the speaker will sing 6 decibels quieter. It’s about an octave lower (500/2=250gz), 12dB quieter, 125gz 18dB quieter, 63gz 24dB quieter, and so on.If you were to cut it in 2nd order (12dB/oct), you would lose 12dB at 500 Hz, 24dB at 250 Hz, 36dB at 125 Hz, and 48dB at 63 Hz.So you can calculate any order of the filter at different frequencies.

An example, of course, is extremely simplistic and crude. The speed and uniformity of the decay will depend on another 100500 factors, but in principle the example reflects the essence we need. Precisely because a squeaker will always sing and below the cutoff frequency, it is highly discouraged to make a cutoff near their resonant frequency below which they become extremely difficult to operate. This will reduce its volume at best times (you just can’t pile up the volume at full volume without distortion). At worst the squeaker will die. We learned this fact and moved on. It’s even more complicated and incomprehensible :D.

The next important aspect of this case is to flatten the minds of newcomers to this kind of tablets on the Internet:

The tables are actually correct.would be if it weren’t for one thing. there is no such thing as a 4 ohm, or 2 ohm, or 8 ohm loudspeaker. And it never was. ))

The impedance is not the resistance of the speaker. The second is the MINIMUM impedance the speaker can have.This criterion is very important for the stable operation of the amplifier without overloading. But that doesn’t mean that the impedance can’t be higher with the speaker. I’ll tell you more, it’s almost always higher, the whole question is how much higher and when. (By the way, you can use a multimeter to measure your 4 ohm loudspeakers. It will always be less than a little over 4 ohms. 3.7-3.8m precisely because the impedance is specified and you measure the resistance)) ). So the impedance of the loudspeaker during sound reproduction depends on a heap of factors, starting from the design of the speaker and ending with the registration of speakers (and in fact a horn loudspeaker is a loudspeaker in the speaker deflection) and frequency. Here is the last factor we are especially interested when we talk about HF.If, say, take two four-ohm loudspeakers and measure their impedance at, say, 5 kilohertz, it could turn out that one loudspeaker has an impedance of 5 ohms at this frequency and the other has 7. Then according to the table above, we try to cut them by 5 kilohertz with a capacitor of 8 microfarads. As a result, the first one gets cut at 4 kilohertz, and the second one with the same capacitor gets cut at 3 kilohertz! So the first one will be cutting a shit sound, and the second one will be burning up.To give you an example, here is a graph of the system impedance versus frequency (Z response) for component speakers:

Crossover, filter orders. on the fingers.

Crossovers are devices in sound systems that create the desired operating frequency ranges for the speakers. Speakers are designed to operate within a certain frequency range. They can’t accept frequencies outside of that range. If a low frequency signal is sent to a high frequency speaker (tweeter), the sound picture will be ruined, and if the signal is also powerful, the tweeter will “burn out”. The high-frequency speakers only need to handle the high frequencies, and the low-frequency speakers only need to get the low-frequency range from the overall sound signal. The rest of the middle band goes to the midrange speakers (midwoofers). So the job of the crossover is to divide the audio signal into the right (optimal) frequency bands for the appropriate speaker type.

Simply put, a crossover. is a pair of electrical filters. Let’s say the crossover has a cutoff frequency of 1000 Hz. This means that one of its filters cuts off all frequencies below 1000 Hz and only allows frequencies above 1000 Hz to pass through. This kind of filter is called a high-pass filter. The other filter that allows frequencies below 1000 Hz is called the low-pass. The graphical representation of the crossover is given in Figure 3. The point where the two curves intersect is the crossover cutoff frequency of 1000 Hz. With three-way crossovers, there is also a band-pass filter that only passes through the middle frequency range (around 600 Hz to 5,000 Hz).) This diagram gives the frequency response of the three-way crossover.

Sensitivity order. This is the ratio of the crossover output signal intensity (dB) to the input signal frequency, assuming the input signal intensity is constant. We usually define sensitivity (cut-off slope) as dB/octave. For many mathematical reasons the sensitivity of crossovers is always a multiple of 6 dB/octave. The first order crossover has a sensitivity of 6 dB/octave. The second order crossover has a sensitivity of 12 dB/octave, the third order. 18 dB/octave, and 4th order crossovers have a sensitivity of 24 dB/octave. Consider a third-order low-pass filter with a cut-off frequency of 100 Hz. As mentioned above, this crossover will only pass frequencies below 100 Hz and cut frequencies above 100 Hz. All frequencies above 100 Hz will lose their strength in the filter output by multiples of 18 dB depending on which octave they fall into. So a 200 Hz frequency (first octave above the cut-off frequency) would lose 18 dB, a 400 Hz frequency (second octave) would lose 36 Hz and a third octave (800 Hz) would lose 54 dB. And so on, all subsequent octaves will be attenuated by multiples of 18 dB. A less sensitive first-order low-pass filter with a cut-off frequency of 100 Hz will do the same thing, but the unwanted octaves will be cut back not by 18 dB, but by 6 dB. As you can see, the filters that make up the crossovers are not able to cut off unwanted frequencies at once, but do so gradually, with different sensitivity depending on their order.

First order crossovers. They are the simplest passive crossover and consist of one capacitor, and one inductor. The capacitor works like a high-pass filter to protect the tweeter from unnecessary bass and midrange frequencies. The coil is used as a low-pass filter. The sensitivity of first order crossovers is low. Only 6dB per octave. The good thing about these crossovers.No phase shift between the tweeter and the other speaker. Second-order crossovers. They are also called Butterworth crossovers, after the creator of the mathematical model for these crossovers. Constructed with one capacitor and coil on the tweeter and one capacitor and coil on the woofer. They have a higher sensitivity of 12dB/octave, but have a phase shift of 180 degrees, which means that the tweeter and other driver diaphragms move out of sync. To fix the problem you have to reverse the polarity of the wires on the tweeter.

Third order crossovers. These have one coil and two capacitors in the tweeter, but the inverse is true for the bass driver. The sensitivity of these crossovers is 18 dB per octave and they have good phase response in all polarities. Negative feature of 3rd order crossovers. Unacceptable use of time delays to eliminate problems associated with speakers not radiating on the same vertical plane.

Fourth order crossovers. Fourth order Butterworth crossovers have a high sensitivity of 24dB/octave, which dramatically reduces the mutual influence of the speakers in the frequency separation area. Phase shift is 360 degrees, which effectively means no phase shift at all. But the amount of phase shift in this case is not constant and can lead to erratic operation of the crossover. These crossovers are almost never used in practice. Linkwitz and Reeley optimized the fourth order crossover design. This crossover consists of two second order Butterworth crossovers in series for the tweeter, and the same for the bass driver. Their sensitivity is also 24dB per octave, but the output level of each filter is 6dB less than the crossover output. The Linquitz-Realy crossover has no phase shift and allows time correction for drive units not operating on the same physical plane. These crossovers give the best acoustic performance compared to other designs.

As mentioned above, the passive crossover is made up of capacitors and inductors. In order to build a passive first order crossover you must have one capacitor and one inductor. The capacitor is fitted in series with the tweeter (high-pass filter) and the coil in series with the woofer (low-pass filter). The nominal inductance values for the coil ((H. microgeneric) and capacitance ((F. microfarads) are given in the table depending on the desired cut-off frequency of the crossover and the impedance of the speakers. First order crossover (6 dB/octave) For example let’s select the capacitance and inductance for a crossover with a cut off frequency of 4000 Hz and a speaker impedance of 4 Ohms. From the above table we find that the capacitance of the first order capacitor should be equal to 10 mF and the inductance of the coil 0.2 mG. To find the component ratings for a second order (12dB/octave) crossover, multiply the values in the same table for the capacitor by 0.7, and multiply the value for the inductor coil by a factor of 1.414. Remember, a second order crossover requires two capacitors and two inductors. Compose a second order crossover for a cutoff frequency of 4000 Hz. To determine the values for both capacitors, multiply the value from the table of 10 mF by a factor of 0.7 and get 7mF. Next, the inductance value of 0.2 mG times factor 1.414 and get the inductance value for each coil 0.28 mG. I put one of these capacitors in series with the tweeter and one in parallel with the woofer. One coil in parallel with the tweeter and one in series with the woofer.

Re: Need advice on the cuts in the channel

The front is first order, the higher order kills the sound 80 percent of the time. for starters. mids at the bottom around 60-70 Hz or don’t cut it at all, at the top. you need to listen, theoretically from 2 to 3 kiloHts try from 3.5 to 5 kilohertz, also first order.

sub. listen to 3-4-5 order, around 70 hertz.

I have the task of opening up the capabilities of the tweeter. Its frequency range is from 1500(!) to 20000 Hz. Resonance at 800 Hz, I think. That’s why I want to remove as much as possible from the midrange and give it to the tweeter.

Local Brigadier Reputation: 92166 Registration 04.11.2010 City / village St. Petersburg Messages 1,028 Thanks (Share) 229 Thanks (Received) 677

Re: advice on the cuts in the channel

Better to do both smoother (6 or 12 db/oct), so that the overlap was, then the transition will not be sharp from the mids to the tweeters.

Reputation: 669062 Registered 17.12.2008 City / village St. Petersburg Messages 3,542 Thanks (gave away) 5366 Thanks (received) 7318

What is frequency processing?

The process of frequency filtering is to decrease or, conversely, to increase the frequencies in a certain spectrum. Thanks to special devices and plugins, you can make equalization as accurate as possible, removing or adding a few Hertz (the unit of measurement when filtering). Such crossover has a lot of applications: removal of conflicting frequencies, reducing the volume of noises that are unpleasant to the ear, creating the “body” of the sound signal, enriching the recording with harmonics, and much more.

Also, one of the equalizer’s main tasks is to “clear” space in the mix, i.e.е. After processing, each instrument, live or electronic, should occupy its own place and not disturb others. For example, bass sounds are usually located in the center and at the bottom, midrange instruments (guitars, snare drum, keyboards) are in the middle, and vocals are better “raised up” to be heard over all tracks.

It’s also important to focus on removing unpleasant sounds. by moving a few sliders in EQ you can get rid of guitar strings clanking, cymbal noise and vocalists sighing. However, it is important not to overdo it and not to cut out “useful” frequencies, which enrich the sound and make it three-dimensional.

Types of filters

The equalizer contains different types of curves that can be used to filter frequencies. They are divided into:

Limiting Filters

These curves cut off all frequencies behind them ‘permanently’. The degree of slope can be adjusted, going from a vertical straight line (“brick wall”) to a slight cut in the neighborhood of 1-3 dB. These include:

Low Pass (or, on the contrary, High Cut). with this filter, all frequencies above the marked point are removed from Spectra and all frequencies below the marked point are left.

Used mainly to trim the top of the bass and arrange it harmoniously in the mix, as well as to give instruments depth and clarity, remove ringing and rustling.

Most often used to remove bass for instruments whose main frequencies are in the middle and upper range, thus leaving the “bottom” of the mix directly to the bass and kick drum.

Notch filter

Or “band-limiting.”. Cuts frequencies in a narrow line only at a certain bandwidth. Get rid of all unpleasant echoes. A sound engineer’s assistant for spot-processing recordings.

Shelf Filters

They have a straight shape, also divided into High and Low. The former is used to compensate for missing high frequencies and the latter for low frequencies, respectively. You can create a combination of these curves by raising and lowering the frequencies of a track simultaneously, in which case you get a Tilt Shelf.

Presence filter

The most popular is the bell-shaped filter. It has a rounded shape and amplifies the chosen range.

So, for guitars the most often used amplification is around 500 Hz to give a “body” and “roundness” to the sound. And for vocals, for example, it is recommended to raise the frequency close to 5 kHz to move it forward and create the effect of “presence

There is also dynamic equalization, where an equalizer and a compressor work together. In that case, the selected Spectra frequency is not cut out completely during the entire song, but is attenuated only at necessary moments when it reaches a preset threshold. This allows you to achieve flexibility in processing the mix, because the frequency will sound on quiet moments and will not “stick out” on loud.

Re: passive cross to trim the mids at the top

not a bad calculator, just does not present the user information about the phasing of the speakers after the filters depending on the order of the filters.

Reputation: 287836 Registration 21.08.2010 City/Village Moscow Messages 2,696 Thanks (gave away) 1505 Thanks (received) 3007

Re: Passive cross for clipping the midrange at the top

Here the question is already solved. The whole problem is only the passive, I never messed with it. Т.When calculating filters, do we take into account the impedance of each speaker individually or the total impedance of a parallel connection??

If it were possible to implement it, I would not think about a passive Why is it a problem to cut the mids from the top?

Social bookmarks

Social bookmarks

Your Rights

• You cannot post new topics
• You can not reply in threads
• You can not attach attachments
• You can not edit your posts

Powered by vBulletin Version 4.1.12 Copyright © 2022 by vBulletin Solutions, Inc. All rights reserved. SEO by vBSEO ©2011, Crawlability, Inc.Main Translators: zCarot

Super PM System provided by vBSuper_PM (Pro). vBulletin Mods Addons Copyright © 2022 DragonByte Technologies Ltd.User Editable Threads, Thread Admins and Group Moderators provided by Threadmins and Group Moderators (Lite). vBulletin Mods Addons Copyright © 2022 DragonByte Technologies Ltd.MAGNITOLA © 2001-2050 by HoSStiA

Full cut to a specific frequency with EQ. Is it possible? (1 online

You are using an old browser. This and other sites may not display correctly on it.You need to update your browser or try another one.

New Member

Is there such a equalizer which cuts off a certain range of frequencies? For example I need to cut all frequencies up to 200Hz, so that 199Hz and below would be.72db or as little as possible, and 200Hz 0db. Graphically it should look like this: If I’m rambling, don’t scold me strictly, I’m an amateur)

no kidding

Well-Known Member

ArtemHod, the slope of the filter is expressed in dB per octave. Т.е. at a cutoff frequency of 200Hz theoretically the 72dB attenuation will be achieved at a frequency one octave lower, t.е. 100Hz. The 72dB decrease of the signal at 199Hz is only possible in the picture ))))

Don’t believe the comic-like pictures, even though they make it easier to understand, but read the special literature ))

P.S. an experienced “sounder” operates with much less values than 72dB, ))) because even tenths of a decibel change the sound.

And extreme values of parameters have more of a “therapeutic” rather than musical function, eliminating the defects made during recording (for example, as a notch filter)

P.P.S. There is such an expression. The best use of the equalizer is for someone who doesn’t turn it on. )))

To get rid of unnecessary frequencies it is better to choose the instruments/arrangement of microphones, etc.п. methods, i.e.е. Acoustic equalization is preferable to the electric one.

Quick repair of 35 Radiotehnika AC-201

Many people have similar loudspeakers of S-90 series. If they all of a sudden start making noise, don’t throw them away, it’s often quite easy to fix.

The noises came out from the speaker, and in the whole range, and the reason was simple. The lead wires, so-called pigtails, had broken over time. But not surprisingly, they’ve been in business since 1981, 40 years is a long time. Something was still there, but the contact was broken during operation, and they were just sparking there, like the first radio transmitter of A.С. Popov, hence the interference across the spectrum. I don’t have any ready-made pigtails and I don’t want to order them and wait a couple of months. Made them from a laptop loop, those wires that go to the matrix have quite thin strands of conductors, and are designed for repeated bending, opening-closing the lid. I braided three pairs of wires. The wires are in insulation, so I didn’t put any special corded strings inside. Just braided and tinned without stripping the insulation, it’s pretty easy to remove with a soldering iron. Can be made of MHTF wire, but they have a thicker cross-section than those on the laptop matrix, and MHTF must be pre-scrubbed insulation. Solder must be roughly observing the direction of the original, after soldering smeared glue B-7000 soldering points and a centimeter of braids from the soldering point. Because they’re going to vibrate all the time, you have to minimize the sharp bends. Well, in general it took a couple of hours to repair both speakers. Since one of them squeaked and the other one replaced the pigtails, not to get up twice as they say))

Tested at maximum power with a sweep generator signal, no unnecessary sounds or resonances. Well, not counting the fact that the shelf hit and rattled a little, but that should finalize the room rather than the speakers ))

The speakers are powered by a home-built VV Sukhov tube amplifier from 1989. I have written about them before, VV Sukhov 1989. Second set. Restoring

Continuation of the post “Restoration of the loudspeaker GD-01-25, aka 75 GDN-01, of the Torii factory

In fact, time flies fast. Looking at the waybill, exactly two years have passed since I ordered the speaker hangers. Well, what can you do, time is always short, even those who do nothing ))) And if you have a hobby, garden, farm, chickens Well, you get it ))

All right, that’s lyrics, here’s the physics. Scraped off the crap that the suspension of the speakers had turned into in 32 years. On this speaker a ring of rubber fell out by itself, in the previous one I pressed with two screwdrivers, here I just slightly pulled.

But the remnants of the sealant on the back side of the driver a little better preserved, apparently it was used in order to the border nickel foam does not cut the soft suspension, so formed a smooth transition from hard to soft.

I have Gerlene, I just need a volatile solvent for it, so that it dries quickly and does not smell. Gerlen is polyisobutylene, but I also have butyl rubber, it seems to me more stable. I just happened to find a phrase about Guerlain (polyisobutylene) “Long meh. processing at temperatures below 100 C leads to destruction”.

In fact it turns out he is not suitable for dynamic structures. But it is widely used for damping suspensions and diffusers. Well, if there’s any doubt, I’ll use butyl rubber. The only thing about it is this: “Butyl rubber is a component of solid rocket fuel.” )) But I will not shoot with it, so I am looking for more.

Germeplast is also there, but it has shriveled over time and in places became like cottage cheese, unlike Guerlain, which flowed in a large mass, and dried in a small one.

Well, okay, butyl rubber is dissolved by aromatic hydrocarbons, which is exactly what I wanted to avoid, but apparently I have to smell. The Internet recommends isopentane, but it is sold from 10 kilos, and it is listed as banned, and it is sad that I do not have it. Internet does not give a direct answer what else to dissolve butyl rubber, but xylene is a mixture of aromatic hydrocarbons (ortoxylene, methaxylene, peroxylene), which I need ))

But it does affect polyurethane foam. The pendant swelled up on the reaction test. I’ll wait until it dries, maybe it will return to the original form of the piece on which I tried.

The Internet on the request “compounds for damping suspensions” gives a lot of audiophile nonsense without any physics. From brake grease to throwing it away!

You have no idea how much bullshit audiophiles talk about. But what can you do, it’s a religion and a belief in miracles. And I’m a practitioner and agnostic, I need results, not a peacock tail.

At this point, after reading all kinds of nonsense, including the ones written by me, I went to the wine cellar and drank my homemade Hennessy, For a while I did not care about Thiel and Small, even Hertz moved away, and the resonance was silenced for a while.

Well, in general, electroacoustics is a mess, and I’d rather not be touched by fans of cherry wood stands for inter-unit cables and wires. It’s puffy, but you have to see the banks, too. Oxygen-free copper and 24-karat gold-plated are outright nonsense.

But let’s go back to butyl rubber mixed with xylene. The process is clearly moving, the mixture is homogenized, the control sample of polyurethane with a drop of this composition is aligned and sticky like the original butyl rubber. I don’t know about the stability of this composition, but I don’t have time to experiment, I’ll take what I have.