I didn’t say that the amplifier became non linear its current flow through the VC that’s non linear. It’s not the amplifiers fault that the system is operating in a resonant mode with rising impedance on both sides of the box frequency!
To Sub Or Not To Sub, That Is The Question
- Thread starter Mr. Miyagi
- Start date
All current reflex designs are resonant for efficiency not sound quality! I’m not criticizing your design it has been accepted by the industry! If you saw the impedance curve presented for our MS-6 it is 4 ohms for a broad range minimizing reactive interactions from ambient. There is no resonance at one frequency just efficient loading of the diaphragm for the bass broadband.What is most confusing in this whole debate is that I have completely failed to identify what you present as a big problem during development of our subwoofers. If it is such a huge problem, surely I would have encountered this and found it to be problematic. But that has not happened.
So, I am not completely sure what is happening.
Let me try again to explain / repeat what you are claiming in my own words.
You are suggesting that the driver cone is activated by the room modes, and this is the reason the response is not even? While with your superdamped design, this does not happen, which results in the response in-room being even/smooth despite the room modes?
Yes! All speakers operate in reverse as microphones. The large diameter of subwoofers and the fact that the amp loses control when operating in the range of resonance make them super sensitive to external pressure from room modes. The fact that we are able to hold the impedance low means the driver is not sensitive and will not exaggerate the nulls. The room is a pressure vessel to contain the energy. You build pressure in the room when modes are ignored by the driver. Bass detail is reproduced when the amp has direct control of the driver.
When resonance is not involved the subwoofer can be integrated with the mains with little effort. The subwoofer placement is also simplified with a center location between the mains a logical choice if one is used. Higher crossovers points typically require two subwoofers located near each mains.
Can you then explain why nearfield measurements of traditional subwoofers done in-room do not show the room modes?
Because the direct output near the sub dominates! Even though the resonate subs acoustic impedance varies it dominates near the sub.The modes show as you move away from the sub. Sums and nulls are obvious as the reflections and direct output pressures normalize in the room. If the direct output is from a low acoustic impedance source it dominates throughout the room.
This make no practical sense. The reason why the room modes dominate more as you move away from the sub is because their origin is the room, not the subwoofer. If the subwoofer itself created so much variance in the response that we see several dB peaks and nulls at the listening position, this would obviously be present when we measure nearfield as well. What is rather the case, is that the microphonic effect you talk about is so microscopic (if present at all) that it makes no meaningful difference.
You have an interesting theory, but I am afraid it is wrong / false. What remains to prove otherwise is to do a in-room comparison measurement with your sub versus a traditional sub (as requested several times). If you are unable or unwilling to do so yourself, feel free to send one here, and I can do the test for you.
We started TBI based on that theory! Our first products were the Magellan subwoofers! Our customers are high end not willing to use a conventional subwoofer for the reasons stated! There are many reviews on those products if you Google the subject. You will read in those reviews why the customers had success. The new MS-6 subwoofer from TBI builds on that theory with additional research on the subject and an even more thorough approach to using the initial tech. We will introduce additional models with larger drivers an 75% less enclosure volumes still resisting the room and integration issues.This make no practical sense. The reason why the room modes dominate more as you move away from the sub is because their origin is the room, not the subwoofer. If the subwoofer itself created so much variance in the response that we see several dB peaks and nulls at the listening position, this would obviously be present when we measure nearfield as well. What is rather the case, is that the microphonic effect you talk about is so microscopic (if present at all) that it makes no meaningful difference.
You have an interesting theory, but I am afraid it is wrong / false. What remains to prove otherwise is to do a in-room comparison measurement with your sub versus a traditional sub (as requested several times). If you are unable or unwilling to do so yourself, feel free to send one here, and I can do the test for you.
If you don’t understand the damaging effects of resonance on accurate sound reproduction you should investigate it! Resonance is a time consuming mode for any machine wherein destruction can result in certain instances. You can’t input a control element when a device is in this high impedance resonate state. It’s a universal situation unless all you want is uncontrollable efficiency. Damping an intentionally resonant device is not solving the problem for control it further inhibits control. Resonance must not be introduced into the moving system if you want to control it!
If you have been building subwoofers based on this theory for 20 years or however long it is, I find it interesting that you in all that time have never taken measurements of any them to prove the theory that they excite room modes to a lesser degree than a normal sub.
The reviews doesn't really prove anything. Reviewers like normal subs too.
Good reviews sell products! You won’t find too many users with panel speakers using the resonate boxes in their system. Most sub business goes to the HT users that are not so concerned. Read the reviews for more understanding of why they say it’s a first!
The proof is in the observation! This is the year 2024 and at this point loudspeaker tech is still founded in the 1940’s and 1950’s. The idiosyncratic behavior of loudspeakers continues with no change or innovation in sight. Everything has to be big going against all other technologies where minimal footprint is desired. Can you name one other speaker company focusing on small, better sound and greater efficiency.
I worked with Ga tech engineers from the 1970’s that let me know that observing sound was still an adventurous endeavor. One with degrees in electrical, chemistry and physics told me
that when it comes to sound if it works use it! These knowledgeable gentleman have since passed but they left me with an open mind.
Adding mass to the low frequency moving system for a lower resonance goes completely against the use of mid and high frequency drivers where the resonant frequency is avoided completely for stated reasons. It was chosen by the industry to resonate the subwoofer for more bass output not more accurate bass! We are the first company to successfully challenge that decision. There is no more Hoffmans Iron Law preventing small enclosures from being used to output efficient and accurate low frequencies. Enclosures for all diameter drivers can now be 75% smaller with better results all around!
Not trying to change the momentum of any manufacturer! Good for discussion knowledge eludes us if are satisfied.
FYI: Your comments on compression and rarefaction lead me to do some research, and discover some basic educational videos.
Thank you for contributions.
I know stuff, I forget stuff, then relearn stuff in a new light and deepen my understanding.
In his own way "Musical Bass" (Jan Plummer?) is doing similar, and challenging what I thought I knew, or at least question what I think I know. Maybe I'll learn something?
For me learning something new is the point, and not agreeing with someone and or winning an argument.
Thanks to all.
Think “Acoustic Transmission line” without the negative aspects of tuning, size and complexity. Compare our impedance curves and bass extension with that of the classic but difficult to execute ATL design. ATL theory as expressed on Wikipedia denotes the same characteristics for the ATL that our diminutive MS-6 realizes. The goal for the ATL is to keep the back wave moving away from the diaphragm while loading individual motions along the line. Critical loading is achieved but with line length limiting low frequency extension.
Our highly sophisticated design goes below 20Hz and has no problem with the rooms acoustics. The low mass driver doesn’t have to compress air when it moves. Resonance is not responsible for efficiency. In a typical room, levels above 100db in the lower bass range are achievable using less than 100w with a 6.5 inch driver. These are all characteristics of the ideal Acoustic Transmission Line but with practical dimensions and repeatability. We have brought the design to a 21’st century reality!
A.problem I see with subs that few seem to acknowledge is the impact on the impedance the preamp sees when you start adding interconnects to to the preamp output. That could significantly impact how the main amplifier reacts.
As I circle closer to a sub swarm, I aim to use a single active analog crossover attached to my preamp to control the impedance the preamp sees. All amps will go through it. Main speaker as well as sub. Active control of the main speaker amps will give control over the bass slope and frequency on the main speakers. This alone should give a sense of air and life as the main amps are no longer trying to do low frequency work. Additionally I should be able to better blend the sub to the main. And I have far greater control over the impedance all amps and preamps work with.
As I circle closer to a sub swarm, I aim to use a single active analog crossover attached to my preamp to control the impedance the preamp sees. All amps will go through it. Main speaker as well as sub. Active control of the main speaker amps will give control over the bass slope and frequency on the main speakers. This alone should give a sense of air and life as the main amps are no longer trying to do low frequency work. Additionally I should be able to better blend the sub to the main. And I have far greater control over the impedance all amps and preamps work with.
