The acoustic measurements on the SA2K showed that the speaker has a slight coloration of the sound in the treble range, caused by edge reflections. The Q113 Evolution needs to address this to outperform its predecessor. A waveguide may be the solution.
The tweeter's free-form diaphragm causes sound reflections from the cabinet edges. This colours the sound, because we really only want to hear the sound from the diaphragm. Not the edges.
One of the first tasks in the project was to make some new measurements on the SA2K speaker, to get a measured impression of how good it really is. If you'd like to revisit the blog post, you can find it here. The measurements showed, among other things, some reflections that occur due to the edges of the speaker cabinet being relatively close to the tweeter. The diaphragm distributes the sound at such a large angle that the sound finds its way to the edges and this causes the unfortunate reflections. I've written a post that talks a bit about edge reflections and how to remedy them. You can find it here. Don't forget to read the comments. There is, as always, good knowledge to be gained.
Impact. A frequency measurement directly from the front of the SA2K shows a curved course between 5-8 kHz. These are edge reflections and the result is that the treble sounds a little bit colored and choppy. However, these are edge reflections of the mild kind, but still ....
Same tweeter, new faceplate
The Q113 Evolution is the speaker that, point by point, must be a better design than the SA2K, without being a complete redesign. Therefore, the new tweeter is not that far from the original, design-wise. The SA2K contains a slightly modified version of Scan Speak's D2905/9700 tweeter. Arguably one of the best tweeters available. The replacement that will find its way into the Q113 Evolution is actually the same speaker unit, but with waveguide around the diaphragm. It's called the D2905/9900.
With and without waveguide. Left, the tweeter from SA2K. Right, the tweeter with waveguide for the Q113 Evolution loudspeaker.
We look forward to the test cabinets
The idea is that the new tweeter will reduce edge reflections, so we can enjoy even better sound quality. First, however, some test cabinets have to be built at Hornslet Møbelfabrik. The cabinet drawings are ready, but there needs to be time in the production department, so we're waiting a bit. In the meantime, there are plenty of things to talk about.
Q113 Evolution with space for the tweeter at the top. It is placed in the middle of the cabinet in the expectation that the waveguide prevents edge reflections.
It's all about craftsmanship
In general, this part of the speaker's creation consists of what you might call the speaker builder's craft. That is, the disciplines that are necessary to master if a loudspeaker is really to make it in this world. There are fundamental things in the construction that must be sound and well-considered in order for the sound quality of the speaker to lift the mental roof and move to new heights. Often there are opportunities to make optimizations later in the process, but if you make small mistakes in the speaker's basic construction, the result will just never be really good. It will always put a damper on the musical expressions of the speaker, and the fatal thing is that you don't notice musical details that aren't there, or nuances that don't come through. They're just not there, and the music becomes a bit grey and indifferent.
In that way, the pursuit of higher quality is about both attitude and knowledge. Not unexpectedly, it is often accompanied by a higher price and for some it can be difficult to sort out what you are actually getting for the money. Not all optimisations are worth the money, I think. You may well find that the sound is different without being better when you mess with development, but it all adds up to make speaker building wildly exciting. I would stubbornly claim that the loudspeaker is 50% science and 50% art, because we can really measure, simulate and calculate many things, but the magic of the music only unfolds when the so-called "voicing" of the loudspeaker is done brilliantly. It's the sound of the speaker that you adjust. It is the presentation of the music itself that is organised here and it is very exciting. The listening tests belong to the second half of the project. Right now, we're still doing the science and the craft.
Do you know how to calculate a waveguide?
Unfortunately, we have not been able to find a recipe on how to calculate a waveguide, but the American Earl Geddes has some interesting knowledge on the subject. You can find him here. If you have experiences and opinions about waveguides, please tell us about it in the blog's comment fields. It might help to make us all wiser. Thanks. If you know of speakers that use waveguides or articles that expand on the topic, please post a link. The rest of us can hardly get enough knowledge.
The tweeter for the Q113 Revolution is on its way
It's in the air that the tweeter for the Q113 Revolution will be something that moves the technological fenceposts one step further. I can promise you that, but after a few months of development, it's still a bit of a wait. So I'm not sure if the next blog post will be about the new tweeter. Engineers are working on it.
