Kvalsvoll

A lot has happened since the last update here. I mainly use facebook to post short messages and pictures of what is going on now, and articles are on my web site in the blog-section, products on the product page. Which means no focus on updating this thread. A new very small speaker has been developed, it was due for launch and presentation, and then you-know-what arrived as a free gift from someone I am not very pleased about at the moment. So launch is now postponed indefinitely, until people are able to show interest in speakers and sound again. The new F205 has a preview page, those interested will find it on the products page, link to preview is on the F205 page. The goal for F205 was to create a very small speaker with sound properties similar to large systems, with as few compromises as possible. The result has surprised me a bit. Since I had my F205 pair installed in Room2, I have not reconnected the larger F2, and have no urge to do so. In fact, after installing the first pair for testing, I found I really missed them after shipping them off. They are addictive. The F205 has the same character of clarity and transparency and dynamics as the larger F2, but it is more neutral and the highs are in a different league. Kind of like a huge horn speaker without the coloration, like a sophisticated electrostatic or magnestat with no limits in spl. A picture from Room2, the F205 in front:

This is great, and as you mention - the challenge is how to market sound. The irony is, that it would be easier back in the 80ies - 90ies - before the internet. Today, you are easily lost between all other outstanding and remarkable offerings, and they have a larger marketing budget. Describing sound quality in text is a hopeless exercise. You can never have the receiver understand what you mean, until they actually experience it in person.

Yes, the crossover turns phase 90 deg for each pole, and the resulting delay is not that large compared to what room reflections can do.

I chose processing that resembles some of the problems I see in measurements from systems around. I have some measurements from customers now, and some of those follow the calibration process from start until the customer reaches the crossing between bored and good enough. Some subwoofers introduce so high gd it is impossible to correct for in ordinary av-processors/receivers. Then there is the room. Yes, I could do a better job with frequency response accuracy. Sample material was quickly chosen, drums with more dry character may be easier to hear - or, may be not. Must try it, to confirm. But my reasoning was, that if it shuold be possible to hear on normal music with transient drums, I have updated the article 2 times, with comments, and new sample files. Thank you for taking time to listen to this, and it is interesting to see your impression is close to my own experience. I suspect it is required to have a very good bass-system with decent response - both frequency and timing - to hear this.

I just updated the article with spectrogram charts and subjective impressions from listening in Room2, now at more realistic volume.

Delay is adjustable, and the rest is fixed in the dsp on the bass-system. For a text-book filter there is a delay, and if you adjust delay on mains to remove this, it wqill not sum correctly. But if the slope on the bass-system is different from the text-book, it is possible to end up with something that sums correctly and has zero delay. you end up with flat phase and flat GD.

@maxmercy, yes, this is true. But it is actually possible to remove all gd/phase from the crossover itself, by adjusting slopes and delay. This is also possible to do higher up in frequency, in even in passive crossovers, but then you don't have the option of adjustable delay, so you depend more on simulations to get it right.

Audibility of group delay at low frequencies: https://www.kvalsvoll.com/…/audibility-of-group-delay-at-l…/ It is then confirmed and proven that group delay at low frequencies is audible. This means timing - GD, phase - matter for sound in the bass range, it is not sufficient to tune towards a flat frequency response alone. (Yes, we knew, told you so.. But, now it is actually proven with evidence in a replicable, described, controlled experiement.)

The disaster here is of course the writer of that article will never read you comment, not because he does not want to or does not want to learn how this really works, but because he will never see it. The main problem with audio today seems to be more about communication - getting through with the message. We have the technical solutions, we know the theory, we know how to make this work in a practical audio system.

Yes, something inside the cabinet behind the ports to control acoustic resistance. This is modeled and simulated, at least to some extent. Dimensions and placement of ports, cabinet volume, is nice to get reasonably correct. The damping will always need some experimenting, because it is not straight forward to get good models of the acoustic properties of the damping material. This is not a problem, it does not take much time to get it right. The cabinet does not need to be very deep, but the location of the ports, baffle width, speaker driver size all matter for resulting response. I plan to develop more of this type speakers, with damped ports to control radiation. The F105 is small, with low-cost drivers, I designed them to test the concept. And it works.

New articles in the blog-section, published quite recently: The F105 loudspeaker - review-style article on this small loudspeaker with some quite interesting technical solutions: https://www.kvalsvoll.com/blog/2019/04/23/the-f105-loudspeaker/ (Use google translate for the text that did not make it through the author's translation service.) Bass and sound quality - 4 real world examples: https://www.kvalsvoll.com/blog/2019/03/10/bass-og-lydkvalitet-4-eksempel-fra-den-virkelige-verden/ (Use google translate, it continues to improve, and has now reached a performance level sufficient to make most of my articles understandable in English.) Looking at what is happening around on the net and otherwise, it is quite apparent that audio has died and become sort "Reign of the nonsense". There is no interest for technology, little innovation in new products, what is left of audio press are rendered totally irrelevant, lots of nonsense products gets whatever remains of attention. And there is simply no advancement in knowledge and technology - you find yourself just repeating and trying to explain things that by now should be known ("it is known"), which of course hinders further development up to the next level because you are stuck with this debunking of myths that should not be alive. Most of the really serious enthusiasts now build their own custom systems, which is good, but also not so good for audio as a business, because there simply is no market. Read the articles. Is this interesting? Is it relevant? Is it entertaining? Does it make you inspired to learn more about audio, put on some music and listen, find out what you can do with your own system?

There was some discussion about some subwoofers that were linked to my name, in a different thread. Please feel free to ask or comment, and you can use this thread, no need to start a new one. If you go to my web site, you will see product presentations of the subwoofers I sell, and articles related to those subwoofers and bass in general. All presentations and product info are available in English language, most of the articles as well. What I am going to say now, may seem a little strange: I am not on data-bass to promote my products and services. Actually, I am not that keen to have a discussion about either products or technology, here. There are reasons for that. I want this to be my "free-space", where I can post and talk about things, and not worry about whether what I am saying is good for my own products. But feel free to ask, and I will try to answer. There is a contact-page on the web site, where you can find information on how to get in touch with my company. The company is also on facebook, where you can post public questions, or send private messages if you prefer that. The obscenely large "horn" pictured in that other thread has a story behind it. The driver is a 24", so that thing is quite a bit larger that what it seems like from a quick look at the picture. The origins of this design was that the builder was curious about whether a compact-horn using some 24" drivers he already had, was possible. And it is possible, but even with the chosen tuning it gets very large, and the performance per size-unit is not particularly good. The driver is simply too large. It is a tuning with very large rear chamber and short horn channel, closer to a ported pox with huge port, than a real horn. This design performs a little better than 2x V110 - but those V110 would be half the size of one of these overly huge cabinets. The sound quality, however, should be quite good, as there are no resonances and very smooth response in the intended pass-band, it also has a very low cut-off. He has built several of those now, and it would surprise most of you what they have replaced, how sound quality improved, and I have never seen any complaints or concerns about capacity. Which does not surprise me at all, and I have not even heard them. As for the question - why? They are too large, similar performance can be had in half the size, on paper it may seem like even much smaller than that using regular "mickey-mouse" subwoofers could do the job. So, why on earth choose something like this, even if the price-per-size-unit is extremely good due to cabinet made in construction-chipboard. My take is, that the 'I have a 24"' is the major factor, and combine that with the knowledge that when it comes to bass, the real thing requires something very different from what you find in the typical shop, price is low, and suddenly you find yourself looking at ways to make room for a couple of those small houses inside you listening room.

No place for this in this thread, regardless of what is for sale or not. Go to the Room2-thread, I will make a comment there.

If you have questions about my designs, you can ask in the Room2-thread, I may even answer. As for this specific construction pictured above here, that is not something I sell or build, this is a diy based on technical input provided by me.

Guide to this season of GOT: 1. Go to Braavos to lend money in the bank for a new screen with night-vision. 2. Valyrian steel is definitely not required for the magnet system in your subwoofers. 3. Most important step: Go to data-bass and learn how to apply bass-eq. Oh, it's this thread. 4. Turn it up and enjoy. Part from the non-existing low bass the sound is good enough.